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This Philips QB 3.5/750 Tetrode vacuum tube is designed for use as a High Frequency amplifier and oscillator. It has an output of around 750 watts!
I received it as a gift some years ago and it's been sitting in a box in want of a new home. Since I'm not going to put it into service, I thought I would make up an acrylic display housing for it, so now it sits in my lounge room where I can enjoy it!
This is a big tube - Really big! The tube is 145mm high x 87mm wide.
Want to see what this tube looks like running? Check out this!
historische-elektronik.piranho.de/Hyperlink%20F/EL6471%20...
This 1000w amp has two :)
I found a data sheet on line with a sketch of the base, so was able to transpose this into CorelDRAW. I lasercut the box with enough clearance for the tube to 'float' in the middle. The Philips logo is engraved into the inside-surface of the sides.
Needs your free vote of support at: goo.gl/heBmZ7
With enough votes, it could be made into an actual set by LEGO!
Also, please check out my Minimoog models at: goo.gl/iucWKS
AND
the Prism & Spectrum at: goo.gl/pFTr3v
As more data are received from the Hullbull Remote Space Telescope, images are being selected and processed. Another image from early in the light show heralding the opening of Metropolis 1, a new City of Light created some thousand light years away and presented by the intrepid space-time traveling photographer Alan Jaras. This image is from a large set of high-speed photos documenting the first mini-big bangs created by the impressive dimensional oscillator. Taken a fraction of a second after the previous postings, Metropolis 1 Light Show 1 and Metropolis 1 Light Show 2, this image shows the still expanding new matter starting to diffuse after the initial rapid expansion. Photos showing the collapse of matter back into a temporal black hole and the supernova remnants are still being processed by the Hull Observatory supercomputers.
Non-relativistic quantum mechanics is formulated here in a different way. It is, however, mathematically equivalent to the familiar formulation. In quantum mechanics the probability of an event which can happen in several different ways is the absolute square of a sum of complex contributions, one from each alternative way. The probability that a particle will be found to have a path x(t) lying somewhere within a region of space time is the square of a sum of contributions, one from each path in the region. The contribution from a single path is postulated to be an exponential whose (imaginary) phase is the classical action (in units of ℏ) for the path in question. The total contribution from all paths reaching x, t from the past is the wave function ψ(x, t). This is shown to satisfy Schroedinger's equation. The relation to matrix and operator algebra is discussed. Applications are indicated, in particular to eliminate the coordinates of the field oscillators from the equations of quantum electrodynamics.
© 1948 The American Physical Society
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Manufactured by Nikon Corporation, Japan
Model: c.1995 (produced between 1988-1997)
F4s version: with High Speed Battery Pack MB-21
35mm film Integral-motor SLR system camera
BODY
Lens release: button on the left side of the lens flange
Lens mount: Nikon F mount Lenses usable: AF Nikkor lenses and Nikon MF F-mount lenses
Focus modes: Manual focus with electronic rangefinder and Autofocus
Autofocus:
Autofocus detection system: TTL phase detection system using Nikon advanced AM200 autofocus module
Autofocus detection range: Approx. EV minus 1 to EV 18 at ISO 100 (under Nikon inspection conditions)
Autofocus actuation method: Single Servo or Continuous Servo
Autofocus lock: Possible by lightly pressing shutter release button in Single Servo AF mode or by using AF-L button; simultaneous use with AE-L button possible
Electronic rangefinder: Available in Manual focus mode with AF Nikkor lenses, Ai-type Nikkor lenses including Ai-modified Nikkor lenses and non-Ai-type Nikkor lenses with a maximum aperture of f/5.6 or faster
Exposure metering: Matrix Metering (with Multi-Meter Finder DP-20); Center-Weighted Metering (with Multi-Meter Finder DP-20 or AE Action Finder DA-20); Spot Metering (with any finder)
Exposure meter switch: Activated by lightly pressing shutter release button; stays on for approx. 16 sec. after lifting finger from button
Metering range: EV 0 to EV 21 at ISO 100 with f/1.4 lens; EV 2 to EV 21 with Spot Metering
Exposure control: Manual (M), and Programmed (PH, P), Shutter-Priority (S) and Aperture Priority (A) Auto Exposure
Auto exposure lock: Available by pressing AE-L button while meter is on
Exposure compensation: Possible using exposure compensation dial within ±2 EV range in 1/3 EV steps
Multiple exposure: Via a leveron the right back side of the top plate; setting: 1. Pull the multiple exposure lever toward you and release the shutter. The film will not advance. Multiple exposure lever is automatically reset to the original position. 2. Depress the shutter release button again to take the second shot. Film will advance to the next frame. For more than two shots on the same frame, pull the lever before each additional exposure.
Depth-of-field preview button: Provides visual verification of depth of field; can be previewed in Manual (M) or Aperture Priority (A) mode; coaxial with mirror lockup lever
Reflex mirror: Automatic instant-return type with lockup facility; to lock the reflex viewing mirror in the "up" position, push in the depth-of-field preview button and rotate the mirror lockup lever counterclockwise until it stops. (In this case, exposure meter cannot be used.)
This means that you cannot operate the camera in any auto exposure and/or autofocus mode anymore (even if the viewfinder LCD may indicate information). Any indication of light by the LCD is a result of spurious light entering through the view finder eyepiece. However, you can make use of the camera's suggested metering and use it in Manual mode.
Shutter: Electro-magnetically controlled vertical-travel titanium focal plane shutter; dial on the top plate, Manual and Shutter-Priority Auto Exposure modes
Shutter release: Electromagnetic shutter by magnet trigger, on the top plate
Alternate shutter release button: there is a shutter release button is provided at the bottom of the High Speed Battery Pack MB-21 as well as the Multiple Power High Speed Power Pack MB-23. This is convenient for vertical format shooting. The button can be locked to prevent inadvertent shutter release. Note: all F4 has another release terminal at the bottom rear section.
Shutter speeds: Lithium niobate oscillator-controlled; controlled from 1/8800 to 30 sec. steplessly in PH, P or A mode; set from 1/8800 to 4 sec. in one EV steps in M or S mode; B, T and X (1/250 sec.)
Viewfinder: Nikon Multi-Meter Finder DP-20 provided as standard; SLR pentaprism, High-Eyepoint type; metering system selector, diopter adjustment knob, hot-shoe, compensation dial for focusing screens and eyepiece shutter lever provided; interchangeable with Nikon AE Action Finder DA-20, Nikon 6X High-Magnification Finder DW-21 and Nikon Waist-Level Finder DW-20
Viewfinder information: By LCD - exposure compensation value, frame counter (additive type), metering system in use, shutter speed, aperture, exposure mode, electronic analog display, AE Lock indicator; by ADR window - lens aperture; by LED display - focus indicators, exposure compensation mark and flash ready-light. Illuminator switch provided for dim-light viewing
Viewfinder illuminator switch: When it's dark, use the viewfinder illuminator to light up all viewfinder information. Turn the switch on, and lightly press the shutter release button to illuminate the display. The illuminator automatically switches off as the viewfinder display disappears; it also momentarily switches off during exposure. Beneath the shutter speeds dial
Eyepoint: Approx. 22mm
Focusing screen: Nikon advanced B-type BriteView screen with central focus brackets for autofocus operation; interchangeable with 12 optional screens
Film speed range: ISO 25 to 5000 for DX-coded film; ISO 6 to 6400 in 1/3 EV steps for manual setting Film speed setting: At DX position, automatically set to ISO speed of DX-coded film used; manual override possible
Film loading: Film automatically advances to first frame when shutter release button is depressed once
Auto film loading: The user simply pulls the film leader to the mark closes the camera back then presses the shutter release button - and the camera automatically advances the film to frame #1.A bright LED will lit and stays on for approx. 16 sec. in such case, the film advance operation will halt as well.
Winding: In S (single frame) shooting mode, film automatically advances one frame when shutter is released; in CH (Continuous high speed), CL (Continuous low speed) or Cs (Continuous silent) shooting mode, shots are taken as long as shutter release button is depressed; shooting speed is approx. 5.7 fps (CH), 3.4 fps (CL) or 1.0 fps (Cs) - for Continuous Servo Autofocus, test done with an AF Zoom-Nikkor 35-80mm f/4-5.6D lense, new six AA-type alkaline batteries, shutter speed of 1/250 sec. or faster, at normal temperature.
Frame counter: Two additive types provided - on top of camera and inside viewfinder (LCD)
Re-winding: Choice of automatic or manual; automatically rewinds when film rewind levers (R1) and (R2) are used; takes approx. 8 sec. per 36-exposure roll (with six AA-type batteries); (with six AA-type batteries); stops automatically when film is rewound; manual rewind when R1 lever is used
Self-timer: Electronically controlled 10 sec. exposure delay; blinking LED indicates self timer operation; cancelable; setting: via the last setting on the film advance mode
Hot-shoe: Standard ISO-type hotshoe contact; ready light contact, TTL flash contact, monitor contact
Flash sync:1/60 to 1/250 sec. in PH, P or A mode; in M or S mode, shutter fires at speed set and when set from 1/250 to 1/8800 sec., shutter is automatically set to 1/250 sec.; down to 30 sec. shutter is available by using SB-24, SB-26 or other equivalent Nikon speedlights etc. in rear curtain sync in PH, P or A mode Flash ready-light: Viewfinder LED lights up when Nikon dedicated Speedlight is ready to fire; blinks to warn of poor camera/ Speedlight connection or insufficient light for correct exposure
Flash PC socket: A separate sync terminal is provided on the Nikon F4. Use this terminal to attach flash units which do not have the standard ISO hot shoe.
Batteries: six AA-type alkaline or NiCd batteries
Battery chambers: two, on the High Speed Battery Pack MB-21
Body:metal; Weight:
Serial no. 2.499.403
LENS
AF Nikkor 50mm f/1.8 D
Aperture: f/1.8-f/22
Focus range: 0.45-3m +inf
Serial no. 636334, Made in China
More info: Dating, Ken Rocwell com,
NIKON F-801 (1988)
Set of photos taken with this camera
SPECIFICATIONS (from the instructions manual)
Type of camera - Integral-motor autofocus 35mm single-lens reflex
Picture format - 24mm x 36mm (standard 35mm film format)
Lens mount - Nikon F mount
Lens - AF Nikkor lenses, and other Nikon lenses with Nikon F mount (with limitation) available
Focus modes - Autofocus, and manual focus with electronic rangefinder
Autofocus Autofocus detection system - TTL phase detection system using Nikon advanced AM200 autofocus module
Autofocus detection range - Approx. EV minus I to EV 19 (at ISO100)
Autofocus actuation method - Single servo and continuous servo
Autofocus lock - Possible by lightly pressing shutter release button in Single Servo AF mode or by using AF Lock button
Electronic rangefinder - Available in manual focus mode with an AF Nikkor and other Ai-type Nikkor lenses with a maximum aperture of f/5.6 or faster
Exposure metering - Two types of exposure metering systems - Matrix Metering and Centre-Weighted
Exposure meter switch - Activated by lightly pressing shutter release button; stays on for approx. 8 sec. after lifting finger from button
Metering range - EV 0 to EV 21 (at ISO 100 with f/1.4 lens) f
Exposure modes - Programmed auto (PD, P, PH), shutter-priority auto (S), aperture-priority auto (A) and manual (M) modes
Programmed auto exposure control - Both shutter speed and aperture are set automatically; flexible program in one EV step possible
Shutter-priority auto exposure control - Aperture automatically selected to match manually set shutter speed
Aperture-priority auto exposure control - Shutter speed automatically selected to match manually set aperture
Manual exposure control - Both aperture and shutter speed are set manually
Shutter - Electro magnetically controlled vertical-travel focal-plane shutter
Shutter release - Electromagnetic shutter by motor trigger
Shutter speeds - Lithium niolbate oscillator-controlled speeds from 1/8000 to 30 sec.; electro-magnetically controlled long exposure at B setting
Viewfinder - Fixed eye level pentaprism High-eyepoint type; 0.75X magnification with 50mm lens set at infinity; 92% frame coverage
Eye point - Approx. 19mm
Eyepiece cover - Model DK-8 prevents stray light from entering viewfinder
Focusing screen - Nikon advanced B-type Briteview screen with central focus brackets for autofocus operation
Viewfinder information - The following LCD indications appear: focus indicators, exposure modes, shutter speeds/film speeds, aperture/ exposure compensation value, electronic analogue display, exposure compensation mark; ready-light LED; viewfinder display is illuminated automatically or by pressing the viewfinder illumination button
LCD information - The following indications appear: exposure modes, metering types, exposure compensation, electronic analogue display, shutter speeds/film speeds, aperture/exposure compensation value, film speed setting, DX-coded film speed setting, film advance mode, film installation, film advance and rewind, self-timer, multiple exposure, frame counter/ self-timer duration/number of multiple exposure
Electronic beeper - With power switch in beeper position, beeper sounds in the following cases: operation signals; (1) at end of film roll: (2) when film rewinding is complete; (3) during self-timer operation; alert signals; (1) for over- or underexposure and possible picture blur in PD, P, PH or A mode; (2) when lens is not set to the smallest aperture setting in PD, P, PH or S mode; (3) when non-DX-coded film, damaged film or film with an unacceptable DX code is loaded; (4) such as torn or damaged film during film advance
Auto exposure lock - Available via sliding the AE Lock lever while the meter in on
Film speed range - ISO 25 to 5000 for DX-coded film; ISO 6 to 6400 for manual setting
Film speed setting - At DX position, automatically set to ISO speed of DX-coded film used; with non-DX-coded film, ISO speed is set manually
Film loading - Film automatically advances to first frame when shutter release button is depressed once
Film advance - In S (Single-frame) shooting mode, film automatically advances one frame when shutter is released; in CH (Continuous High) or CL (Continuous Low) shooting mode, shots are taken as long as shutter release button is depressed; in CH mode, shooting speed is approx. 3.3fps, and in CL, approx., 2.0 fps (in Continuous Servo Autofocus or manual focus mode, with new batteries at normal temperatures, and a shutter speed faster than 1/125 sec. in manual exposure mode).
Frame counter - Accumulative type: counts back while film is rewinding
Film rewind - Automatically rewinds by pressing film rewind button and multiple exposure film rewind button; approx. 10 sec. per 24-exposure roll; stops automatically when film is rewound
Self-timer;- Electronically controlled; timer duration can be selected between 2 to 30 sec. in one sec. increments; blinking LED indicates self-timer operation; two-shot self-timer is possible; cancelable
Exposure compensation - Possible using exposure compensation button within ±5 EV range in 1/3 EV steps
Multiple exposure - Up to 9 exposures can be set
Depth of Field preview button;- Provides visual verification of depth of field; can be previewed in A or M mode
Reflex mirror - Automatic, instant-return type
Camera back - Hinged back; exchangeable with Nikon Multi-Control Back MF-21 or Data Back MF-20
Accessory shoe - Standard ISO-type hot-shoe contact; ready-light contact, TTL flash contact, monitor contact
Flash synchronization - 1/60 to 1/250 sec. in PD, P, PH or A mode; in S or M mode, shutter fires at speed set, and when set from /250 to 1/8000 sec., shutter is automatically set to 1/250 sec.; down to 30 sec. shutter is available by using SB-24 in rear-curtain sync
Flash ready-light - Viewfinder LED lights up when Nikon dedicated speedlight is ready to fire; links to warn of poor camera/speedlight connection or insufficient light for correct exposure
Autofocus flash photography - Possible with Nikon Autofocus speedlights SB-24, SB-23, SB-22 or B-20 etc.
Power source - Four AA-type batteries
Lens displayed - AF Nikkor 85 mm 1:1.8
I Invite you to visit my blog at Classic Cameras
The "Oslvanany Oscillator" operated by Grumpy Railtours, included street running on the section of line from Brno Dolní to Výstaviště Brno (Brno Exhibition Centre). 714.028 is seen at the terminus, 07/07/17
Staff Sgt. Corey Crim inspects an oscillator in the Precision Measurement Equipment Laboratory March 28, 2014, at Misawa Air Base, Japan. As part of the PMEL flight, Crim and his coworkers calibrate more than 4,000 units annually for multiple agencies across base. Crim is from the 35th Maintenance Squadron. (U.S. Air Force photo by Senior Airman Derek VanHorn/Released)
I am always interested in new things and today I learned about an interesting musical instrument called a Theremin, that was invented in 1920. The Theremin is an electronic musical instrument in which the tone is generated by two high-frequency oscillators and the pitch controlled by the movement of the performer's hand toward and away from the circuit. She is amazing and I was so happy to hear her playing Jill's Theme (written by Ennio Morricone) an amazing song from my favourite Spaghetti Western.. Once Upon A Time In The West. Here's a link to Ms. Illenyi's performance: www.youtube.com/watch?v=lY7sXKGZl2w
I built a new light painting tool using a lazy susan. First session went really well - Still lots to explore with it.
Nikon D90, long exposure, sooc, light-up susan.
10mhz out, power switch and 15-19v dc in.
the rubidium box is about $150 on ebay (china) and takes 12v dc. it warms up in about 5 minutes and once its locked, its nearly an exact 10.0000000 MHz signal out in sine wave form.
a lot of people are now using these as their 'lab clock' source (modern freq counters and function generators often can use external 10mhz reference clocks instead of their local oscillator).
Needs your free vote of support at: goo.gl/heBmZ7
With enough votes, it could be made into an actual set by LEGO!
Also, please check out my Minimoog models at: goo.gl/iucWKS
AND
the Prism & Spectrum at: goo.gl/pFTr3v
autohypnotically Wit da beatin of da drum come neurophysiological effects. Much fascination surround da role dat da acoustics of da drum play to da player...n all da magic it causes !!....wwhhheeee
www.flickr.com/photos/psychoactivartz/3722386712/sizes/l/...
Onde cerebrali, Musica, Risonanza e Chakra
a cura di Marco Amadeux Stefanelli, Ph.D.
Nel corso della nostra vita quotidiana tutti noi sperimentiamo diversi "stati di coscienza". Per esempio, nell'arco di una giornata, tra la luce del mattino e il buio della notte, ci muoviamo da uno stato ordinario di veglia ai diversi stadi del sonno.
Ma anche gli stati di coscienza "straordinari" fanno parte della nostra comune esperienza: quando ci sentiamo particolarmente "creativi", insolitamente "intuitivi", eccezionalmente "lucidi", profondamente "rilassati".
Ordinari, o straordinari che siano, tutti gli stadi della nostra coscienza sono dovuti all'incessante attivita' elettrochimica del cervello, che si manifesta attraverso "onde elettromagnetiche": le onde cerebrali, appunto.
La frequenza di tali onde, calcolata in 'cicli al secondo', o Hertz (Hz), varia a seconda del tipo di attivita' in cui il cervello e' impegnato e puo' essere misurata con apparecchi elettronici. Gli scienziati suddividono comunemente le onde in "quattro bande", che corrispondono a quattro fasce di frequenza e che riflettono le diverse "attivita' del cervello".
Le onde cerebrali sono fluttuazioni ritmiche delle tensioni fra i componenti del cervello. I quattro stati più comuni di queste onde sono: Delta, Theta, Alpha e Beta. La frequenza di tali onde è relativa allo stato di coscienza e tale stato determina un risultante tipo di emozione e/o funzione mentale.
Tutti gli stati delle onde cerebrali sono presenti in quantità variabili in diverse parti del cervello. Lo stato di coscienza è relativo alle onde dominanti in un dato momento.
Onde cerebrali Delta
Hanno una frequenza tra 0,5 e 4 Hz e sono associate al più profondo rilassamento psicofisico. Le onde cerebrali a minore frequenza sono quelle proprie della mente inconscia, del sonno senza sogni, dell'abbandono totale, delle esperienze di pre-morte e coma. In questo senso vengono prodotte durante i processi inconsci di autogenerazione e di autoguarigione. In questo stato si è solitamente "incoscienti" della realtà fisica. Questo stato di coscienza di solito è privo di sogni e può essere ottenuto da un meditante esperto.
Onde cerebrali Theta
La loro frequenza e' tra i 4 ed i 8 Hz e sono proprie della mente impegnata in attivita' di immaginazione, visualizzazione, ispirazione creativa. Tendono ad essere prodotte ad occhi chiusi e corpo fermo con un intensa attenzione interiore e durante la meditazione profonda, il sogno ad occhi aperti, la fase REM del sonno (cioe', quando si sogna). Nelle attività di veglia le onde Theta sono il segno di una conoscenza intuitiva e di una capacita' immaginativa radicata nel profondo. Genericamente vengono associate alla creativita' e alle attitudini artistiche.
Onde cerebrali Alpha
Hanno una frequenza che varia da 8 a 14 Hz e sono associate a uno stato di coscienza vigile, ma rilassata. La mente, calma e ricettiva, è concentrata sulla soluzione di problemi esterni, o sul raggiungimento di uno stato meditativo leggero. Le onde alfa dominano nei momenti introspettivi, o in quelli in cui più acuta è la concentrazione per raggiungere un obiettivo preciso. Sono tipiche, per esempio, dell'attività cerebrale di chi è impegnato in una seduta di meditazione, yoga, taiji. Nello stato Alpha generalmente si presenta una sincronizzazione e un equilibrio tra emisfero destro e sinistro. In questo stato di solito il livello di endorfine è alto.
Onde cerebrali Beta
Hanno una frequenza che varia da 14 a 30 Hz e sono associate alle normali attivita' di veglia, quando siamo concentrati sugli stimoli esterni, con occhi aperti e focalizzazione esterna. Le onde Beta sono infatti alla base delle nostre fondamentali attivita' di sopravvivenza, di ordinamento, di selezione e valutazione degli stimoli che provengono dal mondo che ci circonda. Per esempio, leggendo queste righe il vostro cervello sta producendo onde Beta. Esse, poi, ci permettono la reazione più veloce e l'esecuzione rapida di azioni. Nei momenti di stress o di ansia le Beta ci danno la possibilita' di tenere sotto controllo la situazione e dare veloce soluzione ai problemi.
Onde cerebrali Gamma
Sono molto rare e relative a frequenze superiori ai 30 Hz nel range da 30 a 90 Hz e prevalentemente 30-42 Hz. Sono tipiche degli stati di meditazione profonda e di grande energia, sono correlate con la volontà, i processi mentali superiori e i poteri psichici, con la concentrazione e il "problem solving" (risoluzione di più problemi contemporaneamente).
Le onde Gamma sono quelle "più recenti" solo perché è stato difficile trovare la strumentazione che le misurasse accuratamente. Si pensa che le frequenze delle onde cerebrali High-Beta e Gamma siano "frequenze di armonizzazione". Le onde Gamma sono associate con la funzione cerebrale che crea una sintesi olografica dei dati raccolti in varie aree del sistema nervoso centrale, affinché si fondano insieme in una prospettiva più elevata.
Recenti sperimentazioni EEG hanno rilevato frequenze cerebrali estremamente elevate sopra le Gamma, fino a 100 cicli al secondo (Hz), che sono state denominate Onde Iper Gamma e onde persino più elevate, a 200 cicli al secondo, denominate Lambda. Sono state rilevate anche onde estremamente basse, più basse delle onde Delta a meno di 0,5 cicli al secondo, che sono state denominate Epsilon.
Queste "nuove onde cerebrali" sono state associate a stati elevati di auto-consapevolezza, capacità di accesso a livelli superiori di informazione ed intuizioni e abilità psichiche ed esperienze extracorporee.
I ritmi Theta e Gamma interagiscono anche con questi nuovi schemi cerebrali per aiutare la concentrazione olografica delle informazioni cerebrali in immagini, pensieri e memorie comprensibili.
Il fenomeno della risonanza
Nel 1665 il fisico e matematico olandese Christiian Huygens, tra i primi a postulare la teoria ondulatoria della luce, osservo' che, disponendo a fianco e sulla stessa parete due pendoli, questi tendevano a sintonizzare il proprio movimento oscillatorio, quasi "volessero assumere lo stesso ritmo". Dai suoi studi deriva quel fenomeno che oggi chiamiamo 'risonanza'. Nel caso dei due pendoli, si dice che uno fa risuonare l'altro alla propria frequenza. Allo stesso modo e per lo stesso principio, se si percuote un diapason, che produce onde alla frequenza fissa di 440 Hz, e lo si pone vicino a un secondo diapason 'silenzioso', dopo un breve intervallo quest'ultimo comincia anch'esso a vibrare.
La risonanza puo' essere utilizzata anche nel caso delle onde cerebrali. Studi che si sono serviti dell'elettroencefalogramma hanno mostrato un' evidente correlazione tra lo stimolo che proviene dall'esterno e le onde cerebrali del soggetto in esame. Inizialmente, le ricerche in questo campo utilizzavano soprattutto la luce; poi, si e' passati ai suoni ed alle stimolazioni elettromagnetiche. Cio' che si e' osservato e' che se il cervello e' sottoposto a impulsi (visivi, sonori o elettrici) di una certa frequenza, la sua naturale tendenza e' quella di sintonizzarsi. Il fenomeno e' detto 'risposta in frequenza'. Per esempio, se l'attivita' cerebrale di un soggetto e' nella banda delle onde beta (quindi, nello stato di veglia) e il soggetto viene sottoposto per un certo periodo a uno stimolo di 10 Hz (onde alfa), il suo cervello tende a modificare la sua attivita' in direzione dello stimolo ricevuto.
Il soggetto passa dunque ad uno stato di rilassamento proprio delle onde alfa.
I due emisferi cerebrali
Il cervello umano e' suddiviso in due emisferi:
Destro (Eros):
- sintetico (comprende l'insieme delle parti), concreto, spaziale (coglie le relazioni nello spazio), intuitivo (usa sensazioni e immagini), analogico (usa le metafore), irrazionale, olistico (percepisce le strutture di assieme), atemporale e non-verbale. E' la sede delle attivita' creative, musicali, spaziali, espressive e della fantasia.
Sinistro (Logos):
- analitico (comprende i dettagli), astratto (giunge all'interno, partendo dal dettaglio), lineare (lavora in ordine sequenziale), logico, numerico, razionale, sequenziale, simbolico, temporale, verbale e linguistico. E' la sede di tutte quelle attivita' che coinvolgono il linguaggio, la scrittura, il calcolo.
I due emisferi sono uniti da una lamina orizzontale di fibre nervose, il cosiddetto "corpo calloso". Ogni emisfero ha competenze proprie: l'occhio sinistro, l'orecchio sinistro e tutta la parte sinistra del corpo sono connesse all'emisfero destro; l'occhio destro, l'orecchio destro e tutta la parte destra del corpo sono connesse all'emisfero sinistro.I due emisferi, poi, funzionano in modo diverso; elaborano, cioe', tutti i processi informativi, secondo modalita' distinte. Per come si e' finora strutturata, la nostra società da' una maggiore rilevanza alle modalita' di pensiero dell'emisfero sinistro, tanto che fino a poco tempo fa i neurologi definivano "minore" l'emisfero destro. Ma, una visione piu' bilanciata delle due componenti, un maggiore equilibrio tra le funzioni, una armonia tra razionalita' e fantasia e' ciò che, oggi, forse, l'umanita' necessita con piu' urgenza.
Uno strumento semplice ed efficace per riequilibrare il potere dei due emisferi cerebrali e' il suono. Come abbiamo visto, ogni attivita' cerebrale emette onde particolari, che possono entrare in risonanza con le onde sonore esterne. In questo modo il cervello viene 'veicolato' attraverso il suono, stimolato a sintonizzarsi su una frequenza (e quindi sull'attivita' cerebrale che le corrisponde), portato a funzionare come un insieme.
Il ritmo biauricolare
Le onde cerebrali hanno una frequenza che l'orecchio umano non coglie. Ma, l'avvento dell'elettronica e dell'informatica applicata al settore musicale ha dato la possibilita' di utilizzare tali frequenze, veicolandole attraverso onde sonore particolari.
Viene usata una particolare tecnica, chiamata ritmo biauricolare o binaurale, che opera in questo modo: se l'orecchio sinistro viene stimolato con un suono portante alla frequenza, poniamo, di 500 Hz e l'orecchio destro con uno a 510 Hz, la differenza di 10 Hz viene percepita dal cervello (e solo dal cervello, perché è una frequenza che sta al di fuori dello spettro sonoro).
Il cervello e' cosi' stimolato ad entrare in risonanza con il 'ritmo biauricolare' di 10 Hz (onde alfa) e, di conseguenza, con l'attività corrispondente: rilassamento, calma, tranquillità.
Figura 1 - Binaural beat - Battimento binaurale o biauricolare
In figura 1 potete vedere l'analisi in frequenza di un battimento binaurale di 30 Hz (infrasuono) generato da due frequenze diverse per il canale sinistro (424 Hz - blu) e canale destro (454 Hz - rosso) a 0 dB.
Risonanza costruttiva e Chakra
Quando è in salute e bilanciato, ognuno dei sette chakra maggiori umani ruota ad una costante e predeterminata frequenza o vibrazione. Il Chakra della radice ha una frequenza risonante normale di 256 cicli a secondo, o 256 Hz (il Do centrale del pianoforte). Il Chakra seguente per altezza, il Sacrale, risuona a 288 Hz, che è la nota Re. E ogni chakra via via più alto, nel corpo fisico, ha una nota via via più alta della scala, fino al Si. Questi sette toni o note sono chiamati "Ottava 0". Ogni volta che si sale di un'ottava (per esempio dal Do centrale, 256 Hz, al Do più alto della scala, 512 Hz) si può notare come il valore della frequenza raddoppi. Questa caratteristica molto importante è anche uno dei princìpi di risonanza.
Si noti anche che, come il pianoforte ha diverse ottave sopra l'ottava 0, così ne ha anche quel veicolo energetico che chiamiamo "Campo di Energia Umana". Gli Uomini hanno complessivamente cinque ottave associate alla loro Aura, ma solo l'ottava più bassa, la 0, è associata al loro corpo fisico. Ad ottave più alte corrispondono connessioni energetiche tra persone e dimensioni più elevate, partendo dall'ambiente locale della persona (ottava 1), alla Madre Terra in senso Globale (Ottava 2), al nostro sistema solare e in particolare al Sole, l'immediata fonte di tutte le energie "fisiche" che supportano la vita in questo mondo (ottava 3), alla nostra galassia, la via lattea (ottava 4), e all’energia dell’Universo (Ottava 5). Comunque, quando si lavora con la terapia del suono, ci si può concentrare sull'ottava 0, l'ottava associata al corpo fisico e ai suoi maggiori centri di energia.
Se un Chakra è un pò "scordato" e non vibra in armonia, esso può essere ri-accordato attraverso un processo di vibrazione simpatetica. Questo è un concetto base della terapia. Le vibrazioni armoniose alla frequenza corretta entrano direttamente nel campo di rotazione del Chakra e hanno l'effetto di portare quella sequenza vibrazionale del Chakra indietro alla sua frequenza propria così che possa funzionare efficientemente come un transduttore di energie provenienti dal campo di energia universale richiesto dagli organi e ghiandole associati al chakra.
I sette princìpi che caratterizzano il suono e che in ultima analisi determinano gli effetti che il suono ha sul corpo umano e sui suoi sistemi di energia sono: Risonanza, Ritmo, Melodia, Armonia, Tonalità, Timbro e Intonazione.
Risonanza costruttiva
Quando un Chakra risuona ad una particolare vibrazione o frequenza, prende e assorbe energia da quella frequenza. C'è un trasferimento di energia che ha luogo dalla sorgente dell'energia sonora in vibrazione (strumento, voce, coristi...) al chakra stesso. Questo trasferimento che ha luogo nel fenomeno è conosciuto come "Risonanza Simpatica". La risonanza simpatica o simpatetica può essere meglio illustrata osservando due strumenti a corda (Violino, Arpa...) accordati in maniera identica posti l'uno accanto all'altro. Se pizzichiamo la corda del primo strumento, le vibrazioni di quella corda sono sentite dalla stessa corda del secondo strumento, questi inizia ad assorbire l'energia del suono di quella specifica frequenza e quindi inizierà a vibrare a quella frequenza.
Il principio della Risonanza Simpatica è usato nella terapia del suono per riempire ogni chakra con le vibrazioni sonore della frequenza propria. Per introdurre il suono della frequenza propria del Chakra si possono usare sia la voce umana che degli accordatori (coristi). Introducendo la frequenza propria, il livello di vibrazione del Chakra stesso inizia a riequilibrarsi ed armonizzarsi alla sua frequenza.
Un'altra caratteristica del fenomeno della Risonanza Simpatica è che le corde accordate alla stessa nota o ad una o più ottave sopra la nota vibrante, iniziano a vibrare uguale. Per esempio, se un violino ha una corda intonata al Do centrale (256 Hz) e un secondo violino vicino ha una corda accordata ad un'ottava sopra il Do centrale (Do Alto - 512 Hz), quando la corda del Do centrale è pizzicata sul primo violino, il Do alto del secondo violino inizierà a vibrare. Così lavorando con i toni di un'ottava possiamo produrre vibrazioni nelle ottave superiori.
Questo principio è usato nella Terapia del Suono e per creare sopratoni che possano interessare corpi di energia più alta del campo di energia umano. Questi corpi di energia secondari (eterico, emozionale, mentale e spirituale) possono essere pensati come delle ottave superiori al corpo fisico. Così, quando lavoriamo coi Chakra del livello fisico, i sopratoni prodotti hanno lo stesso effetto, attraverso la risonanza simpatica, sulle sequenza di energia di vibrazione dei chakra nei corpi superiori. Tutto questo attraverso una profonda sensazione di benessere, serenità, pace, e connessione attraverso i livelli di energia del soggetto.
Approfondimento ulteriore sui Chakras
Ritmo
L'impulso della Vita è riconosciuto in maniera subliminale quando si sente un suono costantemente ripetuto. Questo per esempio vale per il rullo di tamburo dei circhi. Il Suono forte e rimbombante delle percussioni ripetuto di continuo per diversi minuti, ha l'effetto di portare la mente cosciente in uno stato "alterato". La cadenza o il ritmo del suono ha anche un effetto definito sul corpo umano. Un ritmo molto lento ha un effetto di quiete o sottomissione, mentre un ritmo veloce dà un senso di azione e di movimento.
Melodia
Le melodie e i ricordi sono spesso in relazione e spesso una certa melodia porta alla luce uno specifico ricordo. Alcune melodie fanno sentire leggeri e felici, altre pesanti e depressio. Spesso la Melodia e il Tempo (o Velocità) della stessa si combinano generando una sensazione generale di comfort e benessere. Questo può, alternativamente, stimolare il rilascio di endorfine dal cervello che scioglierà lo stress mentale ed emozionale e ridurrà la tensione ed il dolore, soprattutto se la melodia porta alla luce un ricordo veramente piacevole. Questo riequilibra e aiuta a purificarci dai residui delle energie negative.
Armonia
L'armonia è la combinazione di due o più toni in un accordo. Quando la combinazione ha un suono piacevole, colpisce sia il corpo fisico che le sue energie secondarie in maniera positiva e aiuta il corpo fisico ad accordarsi con le vibrazioni spirituali. L'armonia ci aiuta a trasmutare le condizioni maggiori del corpo e ad "alterare" gli stati di coscienza. Cercando la giusta combinazione di toni e ritmi e della loro armonia, possiamo produrre una risonanza dinamica che corregge ed elimina gli squilibri.
Tonalità
La tonalità è la velocità alla quale le onde sonore vibrano. Più veloci vibrano le onde, più alta sarà la tonalità. Varie sequenze di tonalità possono aiutarci nella frantumazione di pattern di energia rigidi che limitano la nostra crescita, salute e benessere. Tonalità specifiche colpiscono specifici chakra, e questo è il principio applicato dalla terapia attraverso l'uso di precisi accordatori. Ascoltare un brano musicale composto nella tonalità associata al relativo chakra può aiutare a bilanciarlo.
Timbro
Quando strumenti diversi suonano la stessa nota sulla scala (per esempio 512 Hz, un Do sopra il Do centrale del piano), la caratteristica del timbro fa si che ogni suono sia riconosciuto come separato dall'altro. Un flauto, una tromba, un corno francese, un sassofono soprano, una fisarmonica, un oboe possono suonare la stessa nota, ma ogni suono sarà differente dall'altro. Uno può suonare metallico, uno morbido, uno soffice, uno aspro, uno legnoso ecc. Ognuna di queste interpretazioni su come la nota suona interessa anche come noi ci sentiamo sentendo quella particolare nota. Noi reagiamo in maniera prevedibile a differenti timbri della stessa nota o tono.
Intonazione
Quando cresciamo e ci sviluppiamo impariamo a rispondere al suono della voce umana e rispondiamo a questo suono in modi differenti da come risponderemmo al suono di uno strumento musicale. La voce umana ha una presenza e una tonalità che la separa da tutti i suoni che ascoltiamo. E' più personale, più immediata e prende la nostra intera attenzione. A causa di questi fattori, quando ascoltiamo la voce umana, noi rispondiamo su un altro livello emozionale, diverso da quello dei toni musicali, anche se questi suoni sono morbidi e armoniosi. Intonare con la voce umana restaura la sequenza di vibrazione sia del corpo fisico che delle sue energie secondarie così che la nostra essenza spirituale può manifestarsi nella sua pienezza attraverso l'ambiente fisico.
Intervalli e Ottave
In musica si dice intervallo la distanza tra due note o suoni, cioè la differenza d'altezza tra due suoni, esprimibile in fisica acustica tramite il rapporto delle loro frequenze.
A causa della fisiologia di percezione del suono, l'intervallo musicale non è proporzionale alla differenza tra le frequenze dei suoni, ma alla differenza tra i loro logaritmi, cioè al rapporto tra le frequenze, una sorta di distanza numerica tra due suoni che si può verificare tra due suoni prodotti consecutivamente, e in tal caso si parlerà di intervallo melodico o diacronico o salto, oppure tra due suoni prodotti simultaneamente, e si dirà intervallo armonico o sincronico o bicordo.
Nella teoria musicale, gli intervalli si misurano contando le note da quella di partenza a quella di arrivo.
Se si hanno ad esempio un DO e un SOL, l'intervallo è una quinta perché si contano cinque note - DO, RE, MI, FA e SOL. L'intervallo tra il DO e sé stesso non si chiama "di prima", ma unisono.
Si possono poi avere intervalli anche oltre l'ottava: nona, decima, undicesima e tredicesima sono quelli che si trovano menzionati più spesso.
La classificazione degli intervalli musicali costituisce argomento fondamentale nello studio della musica e del suo linguaggio. Un intervallo viene detto armonico quando i suoni che lo formano sono contemporanei e melodico se i suoni che lo formano vengono considerati in successione.
L'intervallo armonico viene sempre considerato ascendente, cioè dal grave verso l'acuto (dal basso verso l'alto). Un intervallo armonico è caratterizzato anche da consonanza e dissonanza, fenomeni legati all'interferenza generata dai due suoni in questione.
Quello melodico invece, a seconda di come è scritto, può essere ascendente o discendente, a seconda che la prima nota sia più grave dell'altra o viceversa. In pratica se ne osserva l'evoluzione in senso temporale. Un intervallo melodico si distingue anche per la direzione, ascendente o discendente, a seconda che il secondo suono sia rispettivamente più acuto o più grave rispetto al primo.
Un intervallo è detto semplice quando sta nell'estensione di un'ottava; se invece ne oltrepassa i limiti si dice composto. Va però detto che alcuni trattati di teoria considerano semplice anche l'intervallo di nona.
L'intervallo più semplice da generare è probabilmente quello di ottava. Esso si ottiene ad esempio sollecitando una corda elastica per produrre la nota più grave, dimezzando quindi la lunghezza della corda e sollecitandola nuovamente per generare la nota più acuta.
Il più piccolo intervallo utilizzato nella musica occidentale è detto semitono. Per motivi storici nel nostro sistema musicale si è scelto convenzionalmente di suddividere l'ottava in 12 semitoni equalizzati, ossia per i quali si mantenga costante il rapporto tra le frequenze degli estremi.
Nella terminologia convenzionale occidentale gli intervalli vengono classificati mediante due parametri che chiameremo ampiezza e specie. Nonostante che tutti i trattati di Teoria e di Armonia concordino nel classificare gli intervalli mediante due parametri, è curioso che in letteratura non esista in proposito una terminologia universalmente accettata. All'occorrenza vengono adottati vocaboli quali denominazione, specie, forma.
Quindi la denominazione degli intervalli si compone di due parti distinte, come ad esempio: quinta giusta, settima eccedente e così via.
Si osservi che la classicazione risulterà del tutto indipendente dalla tonalità in cui l'intervallo si presenta, infatti la definizione univoca di un intervallo dipende esclusivamente dal nome delle note che lo compongono e dal loro stato di alterazione.
Nell'armonia classica o tonale, che poi è quella che viene anche usata per descrivere canzonette, jazz e blues, si suppone che ogni brano possegga una sua tonalità di base (generalmente è l'accordo che termina il ritornello) e tutti gli accordi del pezzo vengono considerati non in assoluto, ma relativamente a quella tonalità.
È vero che si può cambiare tonalità all'interno di una canzone: ad esempio, dopo un giro di DO (DO, LAm, REm, SOL7, DO) si può avere un LA7 e rifare la stessa melodia un tono sopra, ma in questo caso si comincia semplicemente a calcolare tutti gli accordi relativamente alla nuova tonalità.
Si è deciso poi di chiamare gli intervalli relativi alla tonalità di partenza in ben due modi diversi. Il primo è il grado, e non è molto diverso dall'intervallo in sé: la nota della tonalità stessa (il DO, se siamo in DO maggiore) è il primo grado, quella che forma un intervallo di seconda con essa (in questo caso il RE) è il secondo grado, e così via fino al settimo grado.
Ma è anche possibile chiamare le note "per nome". Il primo grado è la tonica, perché dà appunto la tonalità; il secondo grado è la sopratonica.
Passiamo poi alla modale, detta così perché definisce il modo (maggiore o minore) della tonalità, e che sta sul terzo grado. Il quinto grado è la dominante, perché nell'armonia classica è quello più importante subito dopo la tonica; quarto e sesto grado sono rispettivamente sottodominante e sopradominante, il settimo grado è la sensibile. La "settima di dominante", se siamo in tonalità di DO, sarà la nota che fa un intervallo di settima con il SOL, che è la dominante del DO; insomma, un FA.
L'intervallo è un elemento che conferisce contenuto "oggettivo" alla musica, infatti tutte le persone che sperimentano liberamente l'intervallo vivono lo stesso contenuto e la stessa magica energia.
Tutti gli elementi fondamentali della musica possono diventare terapeutici, soprattutto gli intervalli. Ogni melodia ha in sé il contenuto degli intervalli con la quale è formata. Contenuti che spesso agiscono inconsciamente sulla persona.
Una volta compresi, gli intervalli rivelano la musica come un ritmo respiratorio dell'essere che con un continuo movimento ci connette con il Cosmo.
Quando un intervallo risuona a livello fisico il pensare ne valuta l'altezza e il nostro essere più profondo ne sente la qualità.
L'esperienza dell'intervallo, a livello cosciente, è sempre completa ed equilibrata. Tale fenomeno fa parte del ritmo respiratorio animico-spirituale che sta alla base dell'intervallo. Come in ogni inspirazione vi è inclusa l'espirazione relativa e dipendente così pure negli intervalli i due movimenti sono connessi in modo che uno sia "positivo" e l'altro "negativo".
Un parallelo potrebbe essere quello dei colori in cui l'occhio, a livello fisiologico, percependo un colore risponde producendo il colore complementare e quindi polarmente opposto. Si genera così un costante equilibrio tra esterno e interno.
Attraverso una lunga evoluzione, l'essere umano ha forgiato i suoi strumenti, coadiuvato dagli elementi musicali, specialmente gli intervalli. Possiamo dire infatti che l'ottava degli intervalli è la "misura" dell'Uomo.
IP's CARITAS hangs markers, complete with a red oscillator at the bumping post of LaSalle Street. The Rock District's protector engine sits idle a few tracks over. Chicago, IL.
Manufactured by Nikon Corporation, Japan
Model: c.1995 (produced between 1988-1997)
F4s version: with High Speed Battery Pack MB-21
35mm film Integral-motor SLR system camera
BODY
Lens release: button on the left side of the lens flange
Lens mount: Nikon F mount Lenses usable: AF Nikkor lenses and Nikon MF F-mount lenses
Focus modes: Manual focus with electronic rangefinder and Autofocus
Autofocus:
Autofocus detection system: TTL phase detection system using Nikon advanced AM200 autofocus module
Autofocus detection range: Approx. EV minus 1 to EV 18 at ISO 100 (under Nikon inspection conditions)
Autofocus actuation method: Single Servo or Continuous Servo
Autofocus lock: Possible by lightly pressing shutter release button in Single Servo AF mode or by using AF-L button; simultaneous use with AE-L button possible
Electronic rangefinder: Available in Manual focus mode with AF Nikkor lenses, Ai-type Nikkor lenses including Ai-modified Nikkor lenses and non-Ai-type Nikkor lenses with a maximum aperture of f/5.6 or faster
Exposure metering: Matrix Metering (with Multi-Meter Finder DP-20); Center-Weighted Metering (with Multi-Meter Finder DP-20 or AE Action Finder DA-20); Spot Metering (with any finder)
Exposure meter switch: Activated by lightly pressing shutter release button; stays on for approx. 16 sec. after lifting finger from button
Metering range: EV 0 to EV 21 at ISO 100 with f/1.4 lens; EV 2 to EV 21 with Spot Metering
Exposure control: Manual (M), and Programmed (PH, P), Shutter-Priority (S) and Aperture Priority (A) Auto Exposure
Auto exposure lock: Available by pressing AE-L button while meter is on
Exposure compensation: Possible using exposure compensation dial within ±2 EV range in 1/3 EV steps
Multiple exposure: Via a leveron the right back side of the top plate; setting: 1. Pull the multiple exposure lever toward you and release the shutter. The film will not advance. Multiple exposure lever is automatically reset to the original position. 2. Depress the shutter release button again to take the second shot. Film will advance to the next frame. For more than two shots on the same frame, pull the lever before each additional exposure.
Depth-of-field preview button: Provides visual verification of depth of field; can be previewed in Manual (M) or Aperture Priority (A) mode; coaxial with mirror lockup lever
Reflex mirror: Automatic instant-return type with lockup facility; to lock the reflex viewing mirror in the "up" position, push in the depth-of-field preview button and rotate the mirror lockup lever counterclockwise until it stops. (In this case, exposure meter cannot be used.)
This means that you cannot operate the camera in any auto exposure and/or autofocus mode anymore (even if the viewfinder LCD may indicate information). Any indication of light by the LCD is a result of spurious light entering through the view finder eyepiece. However, you can make use of the camera's suggested metering and use it in Manual mode.
Shutter: Electro-magnetically controlled vertical-travel titanium focal plane shutter; dial on the top plate, Manual and Shutter-Priority Auto Exposure modes
Shutter release: Electromagnetic shutter by magnet trigger, on the top plate
Alternate shutter release button: there is a shutter release button is provided at the bottom of the High Speed Battery Pack MB-21 as well as the Multiple Power High Speed Power Pack MB-23. This is convenient for vertical format shooting. The button can be locked to prevent inadvertent shutter release. Note: all F4 has another release terminal at the bottom rear section.
Shutter speeds: Lithium niobate oscillator-controlled; controlled from 1/8800 to 30 sec. steplessly in PH, P or A mode; set from 1/8800 to 4 sec. in one EV steps in M or S mode; B, T and X (1/250 sec.)
Viewfinder: Nikon Multi-Meter Finder DP-20 provided as standard; SLR pentaprism, High-Eyepoint type; metering system selector, diopter adjustment knob, hot-shoe, compensation dial for focusing screens and eyepiece shutter lever provided; interchangeable with Nikon AE Action Finder DA-20, Nikon 6X High-Magnification Finder DW-21 and Nikon Waist-Level Finder DW-20
Viewfinder information: By LCD - exposure compensation value, frame counter (additive type), metering system in use, shutter speed, aperture, exposure mode, electronic analog display, AE Lock indicator; by ADR window - lens aperture; by LED display - focus indicators, exposure compensation mark and flash ready-light. Illuminator switch provided for dim-light viewing
Viewfinder illuminator switch: When it's dark, use the viewfinder illuminator to light up all viewfinder information. Turn the switch on, and lightly press the shutter release button to illuminate the display. The illuminator automatically switches off as the viewfinder display disappears; it also momentarily switches off during exposure. Beneath the shutter speeds dial
Eyepoint: Approx. 22mm
Focusing screen: Nikon advanced B-type BriteView screen with central focus brackets for autofocus operation; interchangeable with 12 optional screens
Film speed range: ISO 25 to 5000 for DX-coded film; ISO 6 to 6400 in 1/3 EV steps for manual setting Film speed setting: At DX position, automatically set to ISO speed of DX-coded film used; manual override possible
Film loading: Film automatically advances to first frame when shutter release button is depressed once
Auto film loading: The user simply pulls the film leader to the mark closes the camera back then presses the shutter release button - and the camera automatically advances the film to frame #1.A bright LED will lit and stays on for approx. 16 sec. in such case, the film advance operation will halt as well.
Winding: In S (single frame) shooting mode, film automatically advances one frame when shutter is released; in CH (Continuous high speed), CL (Continuous low speed) or Cs (Continuous silent) shooting mode, shots are taken as long as shutter release button is depressed; shooting speed is approx. 5.7 fps (CH), 3.4 fps (CL) or 1.0 fps (Cs) - for Continuous Servo Autofocus, test done with an AF Zoom-Nikkor 35-80mm f/4-5.6D lense, new six AA-type alkaline batteries, shutter speed of 1/250 sec. or faster, at normal temperature.
Frame counter: Two additive types provided - on top of camera and inside viewfinder (LCD)
Re-winding: Choice of automatic or manual; automatically rewinds when film rewind levers (R1) and (R2) are used; takes approx. 8 sec. per 36-exposure roll (with six AA-type batteries); (with six AA-type batteries); stops automatically when film is rewound; manual rewind when R1 lever is used
Self-timer: Electronically controlled 10 sec. exposure delay; blinking LED indicates self timer operation; cancelable; setting: via the last setting on the film advance mode
Hot-shoe: Standard ISO-type hotshoe contact; ready light contact, TTL flash contact, monitor contact
Flash sync:1/60 to 1/250 sec. in PH, P or A mode; in M or S mode, shutter fires at speed set and when set from 1/250 to 1/8800 sec., shutter is automatically set to 1/250 sec.; down to 30 sec. shutter is available by using SB-24, SB-26 or other equivalent Nikon speedlights etc. in rear curtain sync in PH, P or A mode Flash ready-light: Viewfinder LED lights up when Nikon dedicated Speedlight is ready to fire; blinks to warn of poor camera/ Speedlight connection or insufficient light for correct exposure
Flash PC socket: A separate sync terminal is provided on the Nikon F4. Use this terminal to attach flash units which do not have the standard ISO hot shoe.
Batteries: six AA-type alkaline or NiCd batteries
Battery chambers: two, on the High Speed Battery Pack MB-21
Body:metal; Weight:
Serial no. 2.499.403
LENS
AF Nikkor 50mm f/1.8 D
Aperture: f/1.8-f/22
Focus range: 0.45-3m +inf
Serial no. 636334, Made in China
More info: Dating, Ken Rocwell com,
Harmosnik is assembled in a Marine Band harmonica case.
Source code: Harmoshnik updates follow the Satashnik tag. This time
I've had a chip that needed some serious calibration for its RC oscillator,
the code update mostly addresses that.
Joana Vasconcelos - Exposição "I'm your mirror"
"Call Center", 2014-2016
Telefones analógicos, aço macio metalizado e termolacado, sistema de som, osciladores acionados por microcontrolador
Analog telephones, soft metallized and thermo-lacquered steel, sound system, microcontroller driven oscillators
I've decided to add a few more tube radios into the photostream. This is a Canadian made (Toronto, Ontario) Addison B2 circa 1946-47. In it's day it was a fairly basic/affordable radio utilizing an AA5 (All American Five) tube line up.....further down in this description you can read a description of that technology taken from Wikipedia.
These days this is considered to be a "not-so-common", desirable radio. They are very hard to find and collectors seem to like the waterfall speaker grill.
The ivory portion of this cabinet is plaskon and the burgundy trim is made from bakelite.
From Wikipedia:
"The All American Five was a mass-produced, superheterodyne radio receiver with five vacuum tubes first designed and produced in the USA in the 1930s.
The radio was called the "All American Five" because the design represented the majority of radios manufactured for home use in the USA in the tube era. The design was also popular in Canada, with the last examples made being inexpensive Japanese units. They were manufactured in the millions by hundreds of manufacturers from the 1930s all the way through to the end of the vacuum tube era.
The philosophy behind the design was simple: it had to be as cost-effective to make as possible. The design was optimised to provide good performance for the price. AA5 designs were also called AC/DC receivers because they could operate on DC mains (which was still in use in several areas of the USA when the design was developed) voltage as well as AC, though this was incidental to the design objective. Of course, when operated on DC, they would only work if the plug was in the correct polarity.
Many design tricks were used to reduce production costs of the five-tube radio. The heaters of the vacuum tubes were all rated to use the same current, so they could be operated in series from line voltage. The more-powerful tubes requiring more-powerful heaters (the rectifier and audio output tube) dropped proportionally more of the line voltage across their heaters. The rectifier tube had a tap on the heater to accommodate the dial light. The plate current was often routed through that portion of the rectifier heater, in order to eliminate the need for a separate fuse. As with Christmas tree lights, if one tube heater failed, the entire heater circuit became inoperable.
The radio used a simple half wave rectifier to produce about 160-170 volts of plate voltage. This simple rectifier coupled with the wiring of the heaters in series eliminated the mains transformer.
The frequency mixer was of the pentagrid converter design to save the cost of a separate oscillator tube. The detector and first audio stage were combined with a dual Diode/Triode combination tube. One diode section sometimes provided a separate automatic volume control function."
Short wave receiver. As it arrives, the case has it's top placed in reverse to protect the oscillator board and knobs during transit.
The cat (Felis catus), commonly referred to as the domestic cat or house cat, is the only domesticated species in the family Felidae. Recent advances in archaeology and genetics have shown that the domestication of the cat occurred in the Near East around 7500 BC. It is commonly kept as a house pet and farm cat, but also ranges freely as a feral cat avoiding human contact. It is valued by humans for companionship and its ability to kill vermin. Because of its retractable claws it is adapted to killing small prey like mice and rats. It has a strong flexible body, quick reflexes, sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It also secretes and perceives pheromones.
Female domestic cats can have kittens from spring to late autumn in temperate zones and throughout the year in equatorial regions, with litter sizes often ranging from two to five kittens. Domestic cats are bred and shown at events as registered pedigreed cats, a hobby known as cat fancy. Animal population control of cats may be achieved by spaying and neutering, but their proliferation and the abandonment of pets has resulted in large numbers of feral cats worldwide, contributing to the extinction of bird, mammal and reptile species.
As of 2017, the domestic cat was the second most popular pet in the United States, with 95.6 million cats owned and around 42 million households owning at least one cat. In the United Kingdom, 26% of adults have a cat, with an estimated population of 10.9 million pet cats as of 2020. As of 2021, there were an estimated 220 million owned and 480 million stray cats in the world.
Etymology and naming
The origin of the English word cat, Old English catt, is thought to be the Late Latin word cattus, which was first used at the beginning of the 6th century. The Late Latin word may be derived from an unidentified African language. The Nubian word kaddîska 'wildcat' and Nobiin kadīs are possible sources or cognates. The Nubian word may be a loan from Arabic قَطّ qaṭṭ ~ قِطّ qiṭṭ.
The forms might also have derived from an ancient Germanic word that was imported into Latin and then into Greek, Syriac, and Arabic. The word may be derived from Germanic and Northern European languages, and ultimately be borrowed from Uralic, cf. Northern Sámi gáđfi, 'female stoat', and Hungarian hölgy, 'lady, female stoat'; from Proto-Uralic *käďwä, 'female (of a furred animal)'.
The English puss, extended as pussy and pussycat, is attested from the 16th century and may have been introduced from Dutch poes or from Low German puuskatte, related to Swedish kattepus, or Norwegian pus, pusekatt. Similar forms exist in Lithuanian puižė and Irish puisín or puiscín. The etymology of this word is unknown, but it may have arisen from a sound used to attract a cat.
A male cat is called a tom or tomcat (or a gib, if neutered). A female is called a queen or a molly, if spayed, especially in a cat-breeding context. A juvenile cat is referred to as a kitten. In Early Modern English, the word kitten was interchangeable with the now-obsolete word catling.
A group of cats can be referred to as a clowder or a glaring.
Taxonomy
The scientific name Felis catus was proposed by Carl Linnaeus in 1758 for a domestic cat. Felis catus domesticus was proposed by Johann Christian Polycarp Erxleben in 1777. Felis daemon proposed by Konstantin Satunin in 1904 was a black cat from the Transcaucasus, later identified as a domestic cat.
In 2003, the International Commission on Zoological Nomenclature ruled that the domestic cat is a distinct species, namely Felis catus. In 2007, it was considered a subspecies, F. silvestris catus, of the European wildcat (F. silvestris) following results of phylogenetic research. In 2017, the IUCN Cat Classification Taskforce followed the recommendation of the ICZN in regarding the domestic cat as a distinct species, Felis catus.
Evolution
Main article: Cat evolution
The domestic cat is a member of the Felidae, a family that had a common ancestor about 10 to 15 million years ago. The evolutionary radiation of the Felidae began in Asia during the Miocene around 8.38 to 14.45 million years ago. Analysis of mitochondrial DNA of all Felidae species indicates a radiation at 6.46 to 16.76 million years ago. The genus Felis genetically diverged from other Felidae around 6 to 7 million years ago. Results of phylogenetic research shows that the wild members of this genus evolved through sympatric or parapatric speciation, whereas the domestic cat evolved through artificial selection. The domestic cat and its closest wild ancestor are diploid and both possess 38 chromosomes and roughly 20,000 genes.
Domestication
See also: Domestication of the cat and Cats in ancient Egypt
It was long thought that the domestication of the cat began in ancient Egypt, where cats were venerated from around 3100 BC, However, the earliest known indication for the taming of an African wildcat was excavated close by a human Neolithic grave in Shillourokambos, southern Cyprus, dating to about 7500–7200 BC. Since there is no evidence of native mammalian fauna on Cyprus, the inhabitants of this Neolithic village most likely brought the cat and other wild mammals to the island from the Middle Eastern mainland. Scientists therefore assume that African wildcats were attracted to early human settlements in the Fertile Crescent by rodents, in particular the house mouse (Mus musculus), and were tamed by Neolithic farmers. This mutual relationship between early farmers and tamed cats lasted thousands of years. As agricultural practices spread, so did tame and domesticated cats. Wildcats of Egypt contributed to the maternal gene pool of the domestic cat at a later time.
The earliest known evidence for the occurrence of the domestic cat in Greece dates to around 1200 BC. Greek, Phoenician, Carthaginian and Etruscan traders introduced domestic cats to southern Europe. During the Roman Empire they were introduced to Corsica and Sardinia before the beginning of the 1st millennium. By the 5th century BC, they were familiar animals around settlements in Magna Graecia and Etruria. By the end of the Western Roman Empire in the 5th century, the Egyptian domestic cat lineage had arrived in a Baltic Sea port in northern Germany.
The leopard cat (Prionailurus bengalensis) was tamed independently in China around 5500 BC. This line of partially domesticated cats leaves no trace in the domestic cat populations of today.
During domestication, cats have undergone only minor changes in anatomy and behavior, and they are still capable of surviving in the wild. Several natural behaviors and characteristics of wildcats may have pre-adapted them for domestication as pets. These traits include their small size, social nature, obvious body language, love of play, and high intelligence. Captive Leopardus cats may also display affectionate behavior toward humans but were not domesticated. House cats often mate with feral cats. Hybridisation between domestic and other Felinae species is also possible, producing hybrids such as the Kellas cat in Scotland.
Development of cat breeds started in the mid 19th century. An analysis of the domestic cat genome revealed that the ancestral wildcat genome was significantly altered in the process of domestication, as specific mutations were selected to develop cat breeds. Most breeds are founded on random-bred domestic cats. Genetic diversity of these breeds varies between regions, and is lowest in purebred populations, which show more than 20 deleterious genetic disorders.
Characteristics
Main article: Cat anatomy
Size
The domestic cat has a smaller skull and shorter bones than the European wildcat. It averages about 46 cm (18 in) in head-to-body length and 23–25 cm (9.1–9.8 in) in height, with about 30 cm (12 in) long tails. Males are larger than females. Adult domestic cats typically weigh 4–5 kg (8.8–11.0 lb).
Skeleton
Cats have seven cervical vertebrae (as do most mammals); 13 thoracic vertebrae (humans have 12); seven lumbar vertebrae (humans have five); three sacral vertebrae (as do most mammals, but humans have five); and a variable number of caudal vertebrae in the tail (humans have only three to five vestigial caudal vertebrae, fused into an internal coccyx). The extra lumbar and thoracic vertebrae account for the cat's spinal mobility and flexibility. Attached to the spine are 13 ribs, the shoulder, and the pelvis. Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones which allow them to pass their body through any space into which they can fit their head.
Skull
The cat skull is unusual among mammals in having very large eye sockets and a powerful specialized jaw. Within the jaw, cats have teeth adapted for killing prey and tearing meat. When it overpowers its prey, a cat delivers a lethal neck bite with its two long canine teeth, inserting them between two of the prey's vertebrae and severing its spinal cord, causing irreversible paralysis and death. Compared to other felines, domestic cats have narrowly spaced canine teeth relative to the size of their jaw, which is an adaptation to their preferred prey of small rodents, which have small vertebrae.
The premolar and first molar together compose the carnassial pair on each side of the mouth, which efficiently shears meat into small pieces, like a pair of scissors. These are vital in feeding, since cats' small molars cannot chew food effectively, and cats are largely incapable of mastication.: Cats tend to have better teeth than most humans, with decay generally less likely because of a thicker protective layer of enamel, a less damaging saliva, less retention of food particles between teeth, and a diet mostly devoid of sugar. Nonetheless, they are subject to occasional tooth loss and infection.
Claws
Cats have protractible and retractable claws. In their normal, relaxed position, the claws are sheathed with the skin and fur around the paw's toe pads. This keeps the claws sharp by preventing wear from contact with the ground and allows for the silent stalking of prey. The claws on the forefeet are typically sharper than those on the hindfeet. Cats can voluntarily extend their claws on one or more paws. They may extend their claws in hunting or self-defense, climbing, kneading, or for extra traction on soft surfaces. Cats shed the outside layer of their claw sheaths when scratching rough surfaces.
Most cats have five claws on their front paws and four on their rear paws. The dewclaw is proximal to the other claws. More proximally is a protrusion which appears to be a sixth "finger". This special feature of the front paws on the inside of the wrists has no function in normal walking but is thought to be an antiskidding device used while jumping. Some cat breeds are prone to having extra digits ("polydactyly"). Polydactylous cats occur along North America's northeast coast and in Great Britain.
Ambulation
The cat is digitigrade. It walks on the toes, with the bones of the feet making up the lower part of the visible leg. Unlike most mammals, it uses a "pacing" gait and moves both legs on one side of the body before the legs on the other side. It registers directly by placing each hind paw close to the track of the corresponding fore paw, minimizing noise and visible tracks. This also provides sure footing for hind paws when navigating rough terrain. As it speeds up from walking to trotting, its gait changes to a "diagonal" gait: The diagonally opposite hind and fore legs move simultaneously.
Balance
Cats are generally fond of sitting in high places or perching. A higher place may serve as a concealed site from which to hunt; domestic cats strike prey by pouncing from a perch such as a tree branch. Another possible explanation is that height gives the cat a better observation point, allowing it to survey its territory. A cat falling from heights of up to 3 m (9.8 ft) can right itself and land on its paws.
During a fall from a high place, a cat reflexively twists its body and rights itself to land on its feet using its acute sense of balance and flexibility. This reflex is known as the cat righting reflex. A cat always rights itself in the same way during a fall, if it has enough time to do so, which is the case in falls of 90 cm (3.0 ft) or more. How cats are able to right themselves when falling has been investigated as the "falling cat problem".
Coats
Main article: Cat coat genetics
The cat family (Felidae) can pass down many colors and patterns to their offspring. The domestic cat genes MC1R and ASIP allow for the variety of color in coats. The feline ASIP gene consists of three coding exons. Three novel microsatellite markers linked to ASIP were isolated from a domestic cat BAC clone containing this gene and were used to perform linkage analysis in a pedigree of 89 domestic cats that segregated for melanism.[citation needed]
Senses
Main article: Cat senses
Vision
A cat's nictitating membrane shown as it blinks
Cats have excellent night vision and can see at only one-sixth the light level required for human vision. This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light. Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration. At low light, a cat's pupils expand to cover most of the exposed surface of its eyes. The domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited. A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. This appears to be an adaptation to low light levels rather than representing true trichromatic vision. Cats also have a nictitating membrane, allowing them to blink without hindering their vision.
Hearing
The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz. It can detect an extremely broad range of frequencies ranging from 55 Hz to 79 kHz, whereas humans can only detect frequencies between 20 Hz and 20 kHz. It can hear a range of 10.5 octaves, while humans and dogs can hear ranges of about 9 octaves. Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, which enables it to detect ultrasonic calls made by rodent prey. Recent research has shown that cats have socio-spatial cognitive abilities to create mental maps of owners' locations based on hearing owners' voices.
Smell
Cats have an acute sense of smell, due in part to their well-developed olfactory bulb and a large surface of olfactory mucosa, about 5.8 cm2 (0.90 in2) in area, which is about twice that of humans. Cats and many other animals have a Jacobson's organ in their mouths that is used in the behavioral process of flehmening. It allows them to sense certain aromas in a way that humans cannot. Cats are sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol, which they use to communicate through urine spraying and marking with scent glands. Many cats also respond strongly to plants that contain nepetalactone, especially catnip, as they can detect that substance at less than one part per billion. About 70–80% of cats are affected by nepetalactone. This response is also produced by other plants, such as silver vine (Actinidia polygama) and the herb valerian; it may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.
Taste
Cats have relatively few taste buds compared to humans (470 or so versus more than 9,000 on the human tongue). Domestic and wild cats share a taste receptor gene mutation that keeps their sweet taste buds from binding to sugary molecules, leaving them with no ability to taste sweetness. They, however, possess taste bud receptors specialized for acids, amino acids like protein, and bitter tastes. Their taste buds possess the receptors needed to detect umami. However, these receptors contain molecular changes that make the cat taste of umami different from that of humans. In humans, they detect the amino acids of glutamic acid and aspartic acid, but in cats they instead detect nucleotides, in this case inosine monophosphate and l-Histidine. These nucleotides are particularly enriched in tuna. This has been argued is why cats find tuna so palatable: as put by researchers into cat taste, "the specific combination of the high IMP and free l-Histidine contents of tuna" .. "produces a strong umami taste synergy that is highly preferred by cats". One of the researchers involved in this research has further claimed, "I think umami is as important for cats as sweet is for humans".[87]
Cats also have a distinct temperature preference for their food, preferring food with a temperature around 38 °C (100 °F) which is similar to that of a fresh kill; some cats reject cold food (which would signal to the cat that the "prey" item is long dead and therefore possibly toxic or decomposing).
Whiskers
To aid with navigation and sensation, cats have dozens of movable whiskers (vibrissae) over their body, especially their faces. These provide information on the width of gaps and on the location of objects in the dark, both by touching objects directly and by sensing air currents; they also trigger protective blink reflexes to protect the eyes from damage.: 47
Behavior
See also: Cat behavior
Outdoor cats are active both day and night, although they tend to be slightly more active at night.[88] Domestic cats spend the majority of their time in the vicinity of their homes but can range many hundreds of meters from this central point. They establish territories that vary considerably in size, in one study ranging 7–28 ha (17–69 acres). The timing of cats' activity is quite flexible and varied but being low-light predators, they are generally crepuscular, which means they tend to be more active near dawn and dusk. However, house cats' behavior is also influenced by human activity and they may adapt to their owners' sleeping patterns to some extent.
Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually between 12 and 16 hours, with 13 and 14 being the average. Some cats can sleep as much as 20 hours. The term "cat nap" for a short rest refers to the cat's tendency to fall asleep (lightly) for a brief period. While asleep, cats experience short periods of rapid eye movement sleep often accompanied by muscle twitches, which suggests they are dreaming.
Sociability
The social behavior of the domestic cat ranges from widely dispersed individuals to feral cat colonies that gather around a food source, based on groups of co-operating females. Within such groups, one cat is usually dominant over the others. Each cat in a colony holds a distinct territory, with sexually active males having the largest territories, which are about 10 times larger than those of female cats and may overlap with several females' territories. These territories are marked by urine spraying, by rubbing objects at head height with secretions from facial glands, and by defecation. Between these territories are neutral areas where cats watch and greet one another without territorial conflicts. Outside these neutral areas, territory holders usually chase away stranger cats, at first by staring, hissing, and growling and, if that does not work, by short but noisy and violent attacks. Despite this colonial organization, cats do not have a social survival strategy or a herd behavior, and always hunt alone.
Life in proximity to humans and other domestic animals has led to a symbiotic social adaptation in cats, and cats may express great affection toward humans or other animals. Ethologically, a cat's human keeper functions as if a mother surrogate. Adult cats live their lives in a kind of extended kittenhood, a form of behavioral neoteny. Their high-pitched sounds may mimic the cries of a hungry human infant, making them particularly difficult for humans to ignore. Some pet cats are poorly socialized. In particular, older cats show aggressiveness toward newly arrived kittens, which include biting and scratching; this type of behavior is known as feline asocial aggression.
Redirected aggression is a common form of aggression which can occur in multiple cat households. In redirected aggression there is usually something that agitates the cat: this could be a sight, sound, or another source of stimuli which causes a heightened level of anxiety or arousal. If the cat cannot attack the stimuli, it may direct anger elsewhere by attacking or directing aggression to the nearest cat, dog, human or other being.
Domestic cats' scent rubbing behavior toward humans or other cats is thought to be a feline means for social bonding.
Communication
Main article: Cat communication
Domestic cats use many vocalizations for communication, including purring, trilling, hissing, growling/snarling, grunting, and several different forms of meowing. Their body language, including position of ears and tail, relaxation of the whole body, and kneading of the paws, are all indicators of mood. The tail and ears are particularly important social signal mechanisms in cats. A raised tail indicates a friendly greeting, and flattened ears indicate hostility. Tail-raising also indicates the cat's position in the group's social hierarchy, with dominant individuals raising their tails less often than subordinate ones. Feral cats are generally silent.: 208 Nose-to-nose touching is also a common greeting and may be followed by social grooming, which is solicited by one of the cats raising and tilting its head.
Purring may have developed as an evolutionary advantage as a signaling mechanism of reassurance between mother cats and nursing kittens, who are thought to use it as a care-soliciting signal. Post-nursing cats also often purr as a sign of contentment: when being petted, becoming relaxed, or eating. Even though purring is popularly interpreted as indicative of pleasure, it has been recorded in a wide variety of circumstances, most of which involve physical contact between the cat and another, presumably trusted individual. Some cats have been observed to purr continuously when chronically ill or in apparent pain.
The exact mechanism by which cats purr has long been elusive, but it has been proposed that purring is generated via a series of sudden build-ups and releases of pressure as the glottis is opened and closed, which causes the vocal folds to separate forcefully. The laryngeal muscles in control of the glottis are thought to be driven by a neural oscillator which generates a cycle of contraction and release every 30–40 milliseconds (giving a frequency of 33 to 25 Hz).
Domestic cats observed in a rescue facility have total of 276 distinct facial expressions based on 26 different facial movements; each facial expression corresponds to different social functions that are likely influenced by domestication.
Grooming
Cats are known for spending considerable amounts of time licking their coats to keep them clean. The cat's tongue has backward-facing spines about 500 μm long, which are called papillae. These contain keratin which makes them rigid so the papillae act like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about 2–3 cm (0.79–1.18 in) long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut, as well as regular grooming of the coat with a comb or stiff brush.
Fighting
Among domestic cats, males are more likely to fight than females. Among feral cats, the most common reason for cat fighting is competition between two males to mate with a female. In such cases, most fights are won by the heavier male. Another common reason for fighting in domestic cats is the difficulty of establishing territories within a small home. Female cats also fight over territory or to defend their kittens. Neutering will decrease or eliminate this behavior in many cases, suggesting that the behavior is linked to sex hormones.
When cats become aggressive, they try to make themselves appear larger and more threatening by raising their fur, arching their backs, turning sideways and hissing or spitting. Often, the ears are pointed down and back to avoid damage to the inner ear and potentially listen for any changes behind them while focused forward. Cats may also vocalize loudly and bare their teeth in an effort to further intimidate their opponents. Fights usually consist of grappling and delivering powerful slaps to the face and body with the forepaws as well as bites. Cats also throw themselves to the ground in a defensive posture to rake their opponent's belly with their powerful hind legs.
Serious damage is rare, as the fights are usually short in duration, with the loser running away with little more than a few scratches to the face and ears. Fights for mating rights are typically more severe and injuries may include deep puncture wounds and lacerations. Normally, serious injuries from fighting are limited to infections of scratches and bites, though these can occasionally kill cats if untreated. In addition, bites are probably the main route of transmission of feline immunodeficiency virus. Sexually active males are usually involved in many fights during their lives, and often have decidedly battered faces with obvious scars and cuts to their ears and nose. Cats are willing to threaten animals larger than them to defend their territory, such as dogs and foxes.
Hunting and feeding
See also: Cat food
The shape and structure of cats' cheeks is insufficient to allow them to take in liquids using suction. Therefore, when drinking they lap with the tongue to draw liquid upward into their mouths. Lapping at a rate of four times a second, the cat touches the smooth tip of its tongue to the surface of the water, and quickly retracts it like a corkscrew, drawing water upward.
Feral cats and free-fed house cats consume several small meals in a day. The frequency and size of meals varies between individuals. They select food based on its temperature, smell and texture; they dislike chilled foods and respond most strongly to moist foods rich in amino acids, which are similar to meat. Cats reject novel flavors (a response termed neophobia) and learn quickly to avoid foods that have tasted unpleasant in the past. It is also a common misconception that cats like milk/cream, as they tend to avoid sweet food and milk. Most adult cats are lactose intolerant; the sugar in milk is not easily digested and may cause soft stools or diarrhea. Some also develop odd eating habits and like to eat or chew on things like wool, plastic, cables, paper, string, aluminum foil, or even coal. This condition, pica, can threaten their health, depending on the amount and toxicity of the items eaten.
Cats hunt small prey, primarily birds and rodents, and are often used as a form of pest control. Other common small creatures such as lizards and snakes may also become prey. Cats use two hunting strategies, either stalking prey actively, or waiting in ambush until an animal comes close enough to be captured. The strategy used depends on the prey species in the area, with cats waiting in ambush outside burrows, but tending to actively stalk birds.: 153 Domestic cats are a major predator of wildlife in the United States, killing an estimated 1.3 to 4.0 billion birds and 6.3 to 22.3 billion mammals annually.
Certain species appear more susceptible than others; in one English village, for example, 30% of house sparrow mortality was linked to the domestic cat. In the recovery of ringed robins (Erithacus rubecula) and dunnocks (Prunella modularis) in Britain, 31% of deaths were a result of cat predation. In parts of North America, the presence of larger carnivores such as coyotes which prey on cats and other small predators reduces the effect of predation by cats and other small predators such as opossums and raccoons on bird numbers and variety.
Perhaps the best-known element of cats' hunting behavior, which is commonly misunderstood and often appalls cat owners because it looks like torture, is that cats often appear to "play" with prey by releasing and recapturing it. This cat and mouse behavior is due to an instinctive imperative to ensure that the prey is weak enough to be killed without endangering the cat.
Another poorly understood element of cat hunting behavior is the presentation of prey to human guardians. One explanation is that cats adopt humans into their social group and share excess kill with others in the group according to the dominance hierarchy, in which humans are reacted to as if they are at or near the top. Another explanation is that they attempt to teach their guardians to hunt or to help their human as if feeding "an elderly cat, or an inept kitten". This hypothesis is inconsistent with the fact that male cats also bring home prey, despite males having negligible involvement in raising kittens.:
Play
Main article: Cat play and toys
Domestic cats, especially young kittens, are known for their love of play. This behavior mimics hunting and is important in helping kittens learn to stalk, capture, and kill prey. Cats also engage in play fighting, with each other and with humans. This behavior may be a way for cats to practice the skills needed for real combat, and might also reduce any fear they associate with launching attacks on other animals.
Cats also tend to play with toys more when they are hungry. Owing to the close similarity between play and hunting, cats prefer to play with objects that resemble prey, such as small furry toys that move rapidly, but rapidly lose interest. They become habituated to a toy they have played with before. String is often used as a toy, but if it is eaten, it can become caught at the base of the cat's tongue and then move into the intestines, a medical emergency which can cause serious illness, even death. Owing to the risks posed by cats eating string, it is sometimes replaced with a laser pointer's dot, which cats may chase.
Reproduction
See also: Kitten
The cat secretes and perceives pheromones. Female cats, called queens, are polyestrous with several estrus cycles during a year, lasting usually 21 days. They are usually ready to mate between early February and August in northern temperate zones and throughout the year in equatorial regions.
Several males, called tomcats, are attracted to a female in heat. They fight over her, and the victor wins the right to mate. At first, the female rejects the male, but eventually, the female allows the male to mate. The female utters a loud yowl as the male pulls out of her because a male cat's penis has a band of about 120–150 backward-pointing penile spines, which are about 1 mm (0.039 in) long; upon withdrawal of the penis, the spines may provide the female with increased sexual stimulation, which acts to induce ovulation.
After mating, the female cleans her vulva thoroughly. If a male attempts to mate with her at this point, the female attacks him. After about 20 to 30 minutes, once the female is finished grooming, the cycle will repeat. Because ovulation is not always triggered by a single mating, females may not be impregnated by the first male with which they mate. Furthermore, cats are superfecund; that is, a female may mate with more than one male when she is in heat, with the result that different kittens in a litter may have different fathers.
The morula forms 124 hours after conception. At 148 hours, early blastocysts form. At 10–12 days, implantation occurs. The gestation of queens lasts between 64 and 67 days, with an average of 65 days.
Data on the reproductive capacity of more than 2,300 free-ranging queens were collected during a study between May 1998 and October 2000. They had one to six kittens per litter, with an average of three kittens. They produced a mean of 1.4 litters per year, but a maximum of three litters in a year. Of 169 kittens, 127 died before they were six months old due to a trauma caused in most cases by dog attacks and road accidents. The first litter is usually smaller than subsequent litters. Kittens are weaned between six and seven weeks of age. Queens normally reach sexual maturity at 5–10 months, and males at 5–7 months. This varies depending on breed. Kittens reach puberty at the age of 9–10 months.
Cats are ready to go to new homes at about 12 weeks of age, when they are ready to leave their mother. They can be surgically sterilized (spayed or castrated) as early as seven weeks to limit unwanted reproduction. This surgery also prevents undesirable sex-related behavior, such as aggression, territory marking (spraying urine) in males and yowling (calling) in females. Traditionally, this surgery was performed at around six to nine months of age, but it is increasingly being performed before puberty, at about three to six months. In the United States, about 80% of household cats are neutered.
Lifespan and health
Main articles: Cat health and Aging in cats
The average lifespan of pet cats has risen in recent decades. In the early 1980s, it was about seven years,: 33 rising to 9.4 years in 1995: 33 and an average of about 13 years as of 2014 and 2023. Some cats have been reported as surviving into their 30s, with the oldest known cat dying at a verified age of 38.
Neutering increases life expectancy: one study found castrated male cats live twice as long as intact males, while spayed female cats live 62% longer than intact females.: 35 Having a cat neutered confers health benefits, because castrated males cannot develop testicular cancer, spayed females cannot develop uterine or ovarian cancer, and both have a reduced risk of mammary cancer.
Disease
Main article: List of feline diseases
About 250 heritable genetic disorders have been identified in cats, many similar to human inborn errors of metabolism. The high level of similarity among the metabolism of mammals allows many of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats as animal models in the study of the human diseases. Diseases affecting domestic cats include acute infections, parasitic infestations, injuries, and chronic diseases such as kidney disease, thyroid disease, and arthritis. Vaccinations are available for many infectious diseases, as are treatments to eliminate parasites such as worms, ticks, and fleas.
Ecology
Habitats
The domestic cat is a cosmopolitan species and occurs across much of the world. It is adaptable and now present on all continents except Antarctica, and on 118 of the 131 main groups of islands, even on the isolated Kerguelen Islands. Due to its ability to thrive in almost any terrestrial habitat, it is among the world's most invasive species. It lives on small islands with no human inhabitants. Feral cats can live in forests, grasslands, tundra, coastal areas, agricultural land, scrublands, urban areas, and wetlands.
The unwantedness that leads to the domestic cat being treated as an invasive species is twofold. On one hand, as it is little altered from the wildcat, it can readily interbreed with the wildcat. This hybridization poses a danger to the genetic distinctiveness of some wildcat populations, particularly in Scotland and Hungary, possibly also the Iberian Peninsula, and where protected natural areas are close to human-dominated landscapes, such as Kruger National Park in South Africa. However, its introduction to places where no native felines are present also contributes to the decline of native species.
Ferality
Main article: Feral cat
Feral cats are domestic cats that were born in or have reverted to a wild state. They are unfamiliar with and wary of humans and roam freely in urban and rural areas. The numbers of feral cats is not known, but estimates of the United States feral population range from 25 to 60 million. Feral cats may live alone, but most are found in large colonies, which occupy a specific territory and are usually associated with a source of food. Famous feral cat colonies are found in Rome around the Colosseum and Forum Romanum, with cats at some of these sites being fed and given medical attention by volunteers.
Public attitudes toward feral cats vary widely, from seeing them as free-ranging pets to regarding them as vermin.
Some feral cats can be successfully socialized and 're-tamed' for adoption; young cats, especially kittens and cats that have had prior experience and contact with humans are the most receptive to these efforts.
Impact on wildlife
Main article: Cat predation on wildlife
On islands, birds can contribute as much as 60% of a cat's diet. In nearly all cases, the cat cannot be identified as the sole cause for reducing the numbers of island birds, and in some instances, eradication of cats has caused a "mesopredator release" effect; where the suppression of top carnivores creates an abundance of smaller predators that cause a severe decline in their shared prey. Domestic cats are a contributing factor to the decline of many species, a factor that has ultimately led, in some cases, to extinction. The South Island piopio, Chatham rail, and the New Zealand merganser are a few from a long list, with the most extreme case being the flightless Lyall's wren, which was driven to extinction only a few years after its discovery. One feral cat in New Zealand killed 102 New Zealand lesser short-tailed bats in seven days. In the US, feral and free-ranging domestic cats kill an estimated 6.3 – 22.3 billion mammals annually.
In Australia, the impact of cats on mammal populations is even greater than the impact of habitat loss. More than one million reptiles are killed by feral cats each day, representing 258 species. Cats have contributed to the extinction of the Navassa curly-tailed lizard and Chioninia coctei.
Interaction with humans
Main article: Human interaction with cats
Cats are common pets throughout the world, and their worldwide population as of 2007 exceeded 500 million. As of 2017, the domestic cat was the second most popular pet in the United States, with 95.6 million cats owned and around 42 million households owning at least one cat. In the United Kingdom, 26% of adults have a cat, with an estimated population of 10.9 million pet cats as of 2020. As of 2021, there were an estimated 220 million owned and 480 million stray cats in the world.
Cats have been used for millennia to control rodents, notably around grain stores and aboard ships, and both uses extend to the present day.
As well as being kept as pets, cats are also used in the international fur trade and leather industries for making coats, hats, blankets, stuffed toys, shoes, gloves, and musical instruments. About 24 cats are needed to make a cat-fur coat. This use has been outlawed in the United States since 2000 and in the European Union (as well as the United Kingdom) since 2007.
Cat pelts have been used for superstitious purposes as part of the practice of witchcraft, and are still made into blankets in Switzerland as traditional medicine thought to cure rheumatism.
A few attempts to build a cat census have been made over the years, both through associations or national and international organizations (such as that of the Canadian Federation of Humane Societies) and over the Internet, but such a task does not seem simple to achieve. General estimates for the global population of domestic cats range widely from anywhere between 200 million to 600 million. Walter Chandoha made his career photographing cats after his 1949 images of Loco, an especially charming stray taken in, were published around the world. He is reported to have photographed 90,000 cats during his career and maintained an archive of 225,000 images that he drew from for publications during his lifetime.
Shows
Main article: Cat show
A cat show is a judged event in which the owners of cats compete to win titles in various cat-registering organizations by entering their cats to be judged after a breed standard. It is often required that a cat must be healthy and vaccinated in order to participate in a cat show. Both pedigreed and non-purebred companion ("moggy") cats are admissible, although the rules differ depending on the organization. Competing cats are compared to the applicable breed standard, and assessed for temperament.
Infection
Main article: Feline zoonosis
Cats can be infected or infested with viruses, bacteria, fungus, protozoans, arthropods or worms that can transmit diseases to humans. In some cases, the cat exhibits no symptoms of the disease. The same disease can then become evident in a human. The likelihood that a person will become diseased depends on the age and immune status of the person. Humans who have cats living in their home or in close association are more likely to become infected. Others might also acquire infections from cat feces and parasites exiting the cat's body. Some of the infections of most concern include salmonella, cat-scratch disease and toxoplasmosis.
History and mythology
Main articles: Cultural depictions of cats and Cats in ancient Egypt
In ancient Egypt, cats were worshipped, and the goddess Bastet often depicted in cat form, sometimes taking on the war-like aspect of a lioness. The Greek historian Herodotus reported that killing a cat was forbidden, and when a household cat died, the entire family mourned and shaved their eyebrows. Families took their dead cats to the sacred city of Bubastis, where they were embalmed and buried in sacred repositories. Herodotus expressed astonishment at the domestic cats in Egypt, because he had only ever seen wildcats.
Ancient Greeks and Romans kept weasels as pets, which were seen as the ideal rodent-killers. The earliest unmistakable evidence of the Greeks having domestic cats comes from two coins from Magna Graecia dating to the mid-fifth century BC showing Iokastos and Phalanthos, the legendary founders of Rhegion and Taras respectively, playing with their pet cats. The usual ancient Greek word for 'cat' was ailouros, meaning 'thing with the waving tail'. Cats are rarely mentioned in ancient Greek literature. Aristotle remarked in his History of Animals that "female cats are naturally lecherous." The Greeks later syncretized their own goddess Artemis with the Egyptian goddess Bastet, adopting Bastet's associations with cats and ascribing them to Artemis. In Ovid's Metamorphoses, when the deities flee to Egypt and take animal forms, the goddess Diana turns into a cat.
Cats eventually displaced weasels as the pest control of choice because they were more pleasant to have around the house and were more enthusiastic hunters of mice. During the Middle Ages, many of Artemis's associations with cats were grafted onto the Virgin Mary. Cats are often shown in icons of Annunciation and of the Holy Family and, according to Italian folklore, on the same night that Mary gave birth to Jesus, a cat in Bethlehem gave birth to a kitten. Domestic cats were spread throughout much of the rest of the world during the Age of Discovery, as ships' cats were carried on sailing ships to control shipboard rodents and as good-luck charms.
Several ancient religions believed cats are exalted souls, companions or guides for humans, that are all-knowing but mute so they cannot influence decisions made by humans. In Japan, the maneki neko cat is a symbol of good fortune. In Norse mythology, Freyja, the goddess of love, beauty, and fertility, is depicted as riding a chariot drawn by cats. In Jewish legend, the first cat was living in the house of the first man Adam as a pet that got rid of mice. The cat was once partnering with the first dog before the latter broke an oath they had made which resulted in enmity between the descendants of these two animals. It is also written that neither cats nor foxes are represented in the water, while every other animal has an incarnation species in the water. Although no species are sacred in Islam, cats are revered by Muslims. Some Western writers have stated Muhammad had a favorite cat, Muezza. He is reported to have loved cats so much, "he would do without his cloak rather than disturb one that was sleeping on it". The story has no origin in early Muslim writers, and seems to confuse a story of a later Sufi saint, Ahmed ar-Rifa'i, centuries after Muhammad. One of the companions of Muhammad was known as Abu Hurayrah ("father of the kitten"), in reference to his documented affection to cats.
Superstitions and rituals
Many cultures have negative superstitions about cats. An example would be the belief that encountering a black cat ("crossing one's path") leads to bad luck, or that cats are witches' familiars used to augment a witch's powers and skills. The killing of cats in Medieval Ypres, Belgium, is commemorated in the innocuous present-day Kattenstoet (cat parade). In mid-16th century France, cats would be burnt alive as a form of entertainment, particularly during midsummer festivals. According to Norman Davies, the assembled people "shrieked with laughter as the animals, howling with pain, were singed, roasted, and finally carbonized". The remaining ashes were sometimes taken back home by the people for good luck.
According to a myth in many cultures, cats have multiple lives. In many countries, they are believed to have nine lives, but in Italy, Germany, Greece, Brazil and some Spanish-speaking regions, they are said to have seven lives, while in Arabic traditions, the number of lives is six. An early mention of the myth can be found in John Heywood's The Proverbs of John Heywood (1546)
Husband, (quoth she), ye studie, be merrie now,
And even as ye thinke now, so come to yow.
Nay not so, (quoth he), for my thought to tell right,
I thinke how you lay groning, wife, all last night.
Husband, a groning horse and a groning wife
Never faile their master, (quoth she), for my life.
No wife, a woman hath nine lives like a cat.
The myth is attributed to the natural suppleness and swiftness cats exhibit to escape life-threatening situations. Also lending credence to this myth is the fact that falling cats often land on their feet, using an instinctive righting reflex to twist their bodies around. Nonetheless, cats can still be injured or killed by a high fall.
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The cat (Felis catus), commonly referred to as the domestic cat or house cat, is the only domesticated species in the family Felidae. Recent advances in archaeology and genetics have shown that the domestication of the cat occurred in the Near East around 7500 BC. It is commonly kept as a house pet and farm cat, but also ranges freely as a feral cat avoiding human contact. It is valued by humans for companionship and its ability to kill vermin. Because of its retractable claws it is adapted to killing small prey like mice and rats. It has a strong flexible body, quick reflexes, sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It also secretes and perceives pheromones.
Female domestic cats can have kittens from spring to late autumn in temperate zones and throughout the year in equatorial regions, with litter sizes often ranging from two to five kittens. Domestic cats are bred and shown at events as registered pedigreed cats, a hobby known as cat fancy. Animal population control of cats may be achieved by spaying and neutering, but their proliferation and the abandonment of pets has resulted in large numbers of feral cats worldwide, contributing to the extinction of bird, mammal and reptile species.
As of 2017, the domestic cat was the second most popular pet in the United States, with 95.6 million cats owned and around 42 million households owning at least one cat. In the United Kingdom, 26% of adults have a cat, with an estimated population of 10.9 million pet cats as of 2020. As of 2021, there were an estimated 220 million owned and 480 million stray cats in the world.
Etymology and naming
The origin of the English word cat, Old English catt, is thought to be the Late Latin word cattus, which was first used at the beginning of the 6th century. The Late Latin word may be derived from an unidentified African language. The Nubian word kaddîska 'wildcat' and Nobiin kadīs are possible sources or cognates. The Nubian word may be a loan from Arabic قَطّ qaṭṭ ~ قِطّ qiṭṭ.
The forms might also have derived from an ancient Germanic word that was imported into Latin and then into Greek, Syriac, and Arabic. The word may be derived from Germanic and Northern European languages, and ultimately be borrowed from Uralic, cf. Northern Sámi gáđfi, 'female stoat', and Hungarian hölgy, 'lady, female stoat'; from Proto-Uralic *käďwä, 'female (of a furred animal)'.
The English puss, extended as pussy and pussycat, is attested from the 16th century and may have been introduced from Dutch poes or from Low German puuskatte, related to Swedish kattepus, or Norwegian pus, pusekatt. Similar forms exist in Lithuanian puižė and Irish puisín or puiscín. The etymology of this word is unknown, but it may have arisen from a sound used to attract a cat.
A male cat is called a tom or tomcat (or a gib, if neutered). A female is called a queen or a molly, if spayed, especially in a cat-breeding context. A juvenile cat is referred to as a kitten. In Early Modern English, the word kitten was interchangeable with the now-obsolete word catling.
A group of cats can be referred to as a clowder or a glaring.
Taxonomy
The scientific name Felis catus was proposed by Carl Linnaeus in 1758 for a domestic cat. Felis catus domesticus was proposed by Johann Christian Polycarp Erxleben in 1777. Felis daemon proposed by Konstantin Satunin in 1904 was a black cat from the Transcaucasus, later identified as a domestic cat.
In 2003, the International Commission on Zoological Nomenclature ruled that the domestic cat is a distinct species, namely Felis catus. In 2007, it was considered a subspecies, F. silvestris catus, of the European wildcat (F. silvestris) following results of phylogenetic research. In 2017, the IUCN Cat Classification Taskforce followed the recommendation of the ICZN in regarding the domestic cat as a distinct species, Felis catus.
Evolution
Main article: Cat evolution
The domestic cat is a member of the Felidae, a family that had a common ancestor about 10 to 15 million years ago. The evolutionary radiation of the Felidae began in Asia during the Miocene around 8.38 to 14.45 million years ago. Analysis of mitochondrial DNA of all Felidae species indicates a radiation at 6.46 to 16.76 million years ago. The genus Felis genetically diverged from other Felidae around 6 to 7 million years ago. Results of phylogenetic research shows that the wild members of this genus evolved through sympatric or parapatric speciation, whereas the domestic cat evolved through artificial selection. The domestic cat and its closest wild ancestor are diploid and both possess 38 chromosomes and roughly 20,000 genes.
Domestication
See also: Domestication of the cat and Cats in ancient Egypt
It was long thought that the domestication of the cat began in ancient Egypt, where cats were venerated from around 3100 BC, However, the earliest known indication for the taming of an African wildcat was excavated close by a human Neolithic grave in Shillourokambos, southern Cyprus, dating to about 7500–7200 BC. Since there is no evidence of native mammalian fauna on Cyprus, the inhabitants of this Neolithic village most likely brought the cat and other wild mammals to the island from the Middle Eastern mainland. Scientists therefore assume that African wildcats were attracted to early human settlements in the Fertile Crescent by rodents, in particular the house mouse (Mus musculus), and were tamed by Neolithic farmers. This mutual relationship between early farmers and tamed cats lasted thousands of years. As agricultural practices spread, so did tame and domesticated cats. Wildcats of Egypt contributed to the maternal gene pool of the domestic cat at a later time.
The earliest known evidence for the occurrence of the domestic cat in Greece dates to around 1200 BC. Greek, Phoenician, Carthaginian and Etruscan traders introduced domestic cats to southern Europe. During the Roman Empire they were introduced to Corsica and Sardinia before the beginning of the 1st millennium. By the 5th century BC, they were familiar animals around settlements in Magna Graecia and Etruria. By the end of the Western Roman Empire in the 5th century, the Egyptian domestic cat lineage had arrived in a Baltic Sea port in northern Germany.
The leopard cat (Prionailurus bengalensis) was tamed independently in China around 5500 BC. This line of partially domesticated cats leaves no trace in the domestic cat populations of today.
During domestication, cats have undergone only minor changes in anatomy and behavior, and they are still capable of surviving in the wild. Several natural behaviors and characteristics of wildcats may have pre-adapted them for domestication as pets. These traits include their small size, social nature, obvious body language, love of play, and high intelligence. Captive Leopardus cats may also display affectionate behavior toward humans but were not domesticated. House cats often mate with feral cats. Hybridisation between domestic and other Felinae species is also possible, producing hybrids such as the Kellas cat in Scotland.
Development of cat breeds started in the mid 19th century. An analysis of the domestic cat genome revealed that the ancestral wildcat genome was significantly altered in the process of domestication, as specific mutations were selected to develop cat breeds. Most breeds are founded on random-bred domestic cats. Genetic diversity of these breeds varies between regions, and is lowest in purebred populations, which show more than 20 deleterious genetic disorders.
Characteristics
Main article: Cat anatomy
Size
The domestic cat has a smaller skull and shorter bones than the European wildcat. It averages about 46 cm (18 in) in head-to-body length and 23–25 cm (9.1–9.8 in) in height, with about 30 cm (12 in) long tails. Males are larger than females. Adult domestic cats typically weigh 4–5 kg (8.8–11.0 lb).
Skeleton
Cats have seven cervical vertebrae (as do most mammals); 13 thoracic vertebrae (humans have 12); seven lumbar vertebrae (humans have five); three sacral vertebrae (as do most mammals, but humans have five); and a variable number of caudal vertebrae in the tail (humans have only three to five vestigial caudal vertebrae, fused into an internal coccyx). The extra lumbar and thoracic vertebrae account for the cat's spinal mobility and flexibility. Attached to the spine are 13 ribs, the shoulder, and the pelvis. Unlike human arms, cat forelimbs are attached to the shoulder by free-floating clavicle bones which allow them to pass their body through any space into which they can fit their head.
Skull
The cat skull is unusual among mammals in having very large eye sockets and a powerful specialized jaw. Within the jaw, cats have teeth adapted for killing prey and tearing meat. When it overpowers its prey, a cat delivers a lethal neck bite with its two long canine teeth, inserting them between two of the prey's vertebrae and severing its spinal cord, causing irreversible paralysis and death. Compared to other felines, domestic cats have narrowly spaced canine teeth relative to the size of their jaw, which is an adaptation to their preferred prey of small rodents, which have small vertebrae.
The premolar and first molar together compose the carnassial pair on each side of the mouth, which efficiently shears meat into small pieces, like a pair of scissors. These are vital in feeding, since cats' small molars cannot chew food effectively, and cats are largely incapable of mastication.: Cats tend to have better teeth than most humans, with decay generally less likely because of a thicker protective layer of enamel, a less damaging saliva, less retention of food particles between teeth, and a diet mostly devoid of sugar. Nonetheless, they are subject to occasional tooth loss and infection.
Claws
Cats have protractible and retractable claws. In their normal, relaxed position, the claws are sheathed with the skin and fur around the paw's toe pads. This keeps the claws sharp by preventing wear from contact with the ground and allows for the silent stalking of prey. The claws on the forefeet are typically sharper than those on the hindfeet. Cats can voluntarily extend their claws on one or more paws. They may extend their claws in hunting or self-defense, climbing, kneading, or for extra traction on soft surfaces. Cats shed the outside layer of their claw sheaths when scratching rough surfaces.
Most cats have five claws on their front paws and four on their rear paws. The dewclaw is proximal to the other claws. More proximally is a protrusion which appears to be a sixth "finger". This special feature of the front paws on the inside of the wrists has no function in normal walking but is thought to be an antiskidding device used while jumping. Some cat breeds are prone to having extra digits ("polydactyly"). Polydactylous cats occur along North America's northeast coast and in Great Britain.
Ambulation
The cat is digitigrade. It walks on the toes, with the bones of the feet making up the lower part of the visible leg. Unlike most mammals, it uses a "pacing" gait and moves both legs on one side of the body before the legs on the other side. It registers directly by placing each hind paw close to the track of the corresponding fore paw, minimizing noise and visible tracks. This also provides sure footing for hind paws when navigating rough terrain. As it speeds up from walking to trotting, its gait changes to a "diagonal" gait: The diagonally opposite hind and fore legs move simultaneously.
Balance
Cats are generally fond of sitting in high places or perching. A higher place may serve as a concealed site from which to hunt; domestic cats strike prey by pouncing from a perch such as a tree branch. Another possible explanation is that height gives the cat a better observation point, allowing it to survey its territory. A cat falling from heights of up to 3 m (9.8 ft) can right itself and land on its paws.
During a fall from a high place, a cat reflexively twists its body and rights itself to land on its feet using its acute sense of balance and flexibility. This reflex is known as the cat righting reflex. A cat always rights itself in the same way during a fall, if it has enough time to do so, which is the case in falls of 90 cm (3.0 ft) or more. How cats are able to right themselves when falling has been investigated as the "falling cat problem".
Coats
Main article: Cat coat genetics
The cat family (Felidae) can pass down many colors and patterns to their offspring. The domestic cat genes MC1R and ASIP allow for the variety of color in coats. The feline ASIP gene consists of three coding exons. Three novel microsatellite markers linked to ASIP were isolated from a domestic cat BAC clone containing this gene and were used to perform linkage analysis in a pedigree of 89 domestic cats that segregated for melanism.[citation needed]
Senses
Main article: Cat senses
Vision
A cat's nictitating membrane shown as it blinks
Cats have excellent night vision and can see at only one-sixth the light level required for human vision. This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light. Large pupils are an adaptation to dim light. The domestic cat has slit pupils, which allow it to focus bright light without chromatic aberration. At low light, a cat's pupils expand to cover most of the exposed surface of its eyes. The domestic cat has rather poor color vision and only two types of cone cells, optimized for sensitivity to blue and yellowish green; its ability to distinguish between red and green is limited. A response to middle wavelengths from a system other than the rod cells might be due to a third type of cone. This appears to be an adaptation to low light levels rather than representing true trichromatic vision. Cats also have a nictitating membrane, allowing them to blink without hindering their vision.
Hearing
The domestic cat's hearing is most acute in the range of 500 Hz to 32 kHz. It can detect an extremely broad range of frequencies ranging from 55 Hz to 79 kHz, whereas humans can only detect frequencies between 20 Hz and 20 kHz. It can hear a range of 10.5 octaves, while humans and dogs can hear ranges of about 9 octaves. Its hearing sensitivity is enhanced by its large movable outer ears, the pinnae, which amplify sounds and help detect the location of a noise. It can detect ultrasound, which enables it to detect ultrasonic calls made by rodent prey. Recent research has shown that cats have socio-spatial cognitive abilities to create mental maps of owners' locations based on hearing owners' voices.
Smell
Cats have an acute sense of smell, due in part to their well-developed olfactory bulb and a large surface of olfactory mucosa, about 5.8 cm2 (0.90 in2) in area, which is about twice that of humans. Cats and many other animals have a Jacobson's organ in their mouths that is used in the behavioral process of flehmening. It allows them to sense certain aromas in a way that humans cannot. Cats are sensitive to pheromones such as 3-mercapto-3-methylbutan-1-ol, which they use to communicate through urine spraying and marking with scent glands. Many cats also respond strongly to plants that contain nepetalactone, especially catnip, as they can detect that substance at less than one part per billion. About 70–80% of cats are affected by nepetalactone. This response is also produced by other plants, such as silver vine (Actinidia polygama) and the herb valerian; it may be caused by the smell of these plants mimicking a pheromone and stimulating cats' social or sexual behaviors.
Taste
Cats have relatively few taste buds compared to humans (470 or so versus more than 9,000 on the human tongue). Domestic and wild cats share a taste receptor gene mutation that keeps their sweet taste buds from binding to sugary molecules, leaving them with no ability to taste sweetness. They, however, possess taste bud receptors specialized for acids, amino acids like protein, and bitter tastes. Their taste buds possess the receptors needed to detect umami. However, these receptors contain molecular changes that make the cat taste of umami different from that of humans. In humans, they detect the amino acids of glutamic acid and aspartic acid, but in cats they instead detect nucleotides, in this case inosine monophosphate and l-Histidine. These nucleotides are particularly enriched in tuna. This has been argued is why cats find tuna so palatable: as put by researchers into cat taste, "the specific combination of the high IMP and free l-Histidine contents of tuna" .. "produces a strong umami taste synergy that is highly preferred by cats". One of the researchers involved in this research has further claimed, "I think umami is as important for cats as sweet is for humans".[87]
Cats also have a distinct temperature preference for their food, preferring food with a temperature around 38 °C (100 °F) which is similar to that of a fresh kill; some cats reject cold food (which would signal to the cat that the "prey" item is long dead and therefore possibly toxic or decomposing).
Whiskers
To aid with navigation and sensation, cats have dozens of movable whiskers (vibrissae) over their body, especially their faces. These provide information on the width of gaps and on the location of objects in the dark, both by touching objects directly and by sensing air currents; they also trigger protective blink reflexes to protect the eyes from damage.: 47
Behavior
See also: Cat behavior
Outdoor cats are active both day and night, although they tend to be slightly more active at night.[88] Domestic cats spend the majority of their time in the vicinity of their homes but can range many hundreds of meters from this central point. They establish territories that vary considerably in size, in one study ranging 7–28 ha (17–69 acres). The timing of cats' activity is quite flexible and varied but being low-light predators, they are generally crepuscular, which means they tend to be more active near dawn and dusk. However, house cats' behavior is also influenced by human activity and they may adapt to their owners' sleeping patterns to some extent.
Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually between 12 and 16 hours, with 13 and 14 being the average. Some cats can sleep as much as 20 hours. The term "cat nap" for a short rest refers to the cat's tendency to fall asleep (lightly) for a brief period. While asleep, cats experience short periods of rapid eye movement sleep often accompanied by muscle twitches, which suggests they are dreaming.
Sociability
The social behavior of the domestic cat ranges from widely dispersed individuals to feral cat colonies that gather around a food source, based on groups of co-operating females. Within such groups, one cat is usually dominant over the others. Each cat in a colony holds a distinct territory, with sexually active males having the largest territories, which are about 10 times larger than those of female cats and may overlap with several females' territories. These territories are marked by urine spraying, by rubbing objects at head height with secretions from facial glands, and by defecation. Between these territories are neutral areas where cats watch and greet one another without territorial conflicts. Outside these neutral areas, territory holders usually chase away stranger cats, at first by staring, hissing, and growling and, if that does not work, by short but noisy and violent attacks. Despite this colonial organization, cats do not have a social survival strategy or a herd behavior, and always hunt alone.
Life in proximity to humans and other domestic animals has led to a symbiotic social adaptation in cats, and cats may express great affection toward humans or other animals. Ethologically, a cat's human keeper functions as if a mother surrogate. Adult cats live their lives in a kind of extended kittenhood, a form of behavioral neoteny. Their high-pitched sounds may mimic the cries of a hungry human infant, making them particularly difficult for humans to ignore. Some pet cats are poorly socialized. In particular, older cats show aggressiveness toward newly arrived kittens, which include biting and scratching; this type of behavior is known as feline asocial aggression.
Redirected aggression is a common form of aggression which can occur in multiple cat households. In redirected aggression there is usually something that agitates the cat: this could be a sight, sound, or another source of stimuli which causes a heightened level of anxiety or arousal. If the cat cannot attack the stimuli, it may direct anger elsewhere by attacking or directing aggression to the nearest cat, dog, human or other being.
Domestic cats' scent rubbing behavior toward humans or other cats is thought to be a feline means for social bonding.
Communication
Main article: Cat communication
Domestic cats use many vocalizations for communication, including purring, trilling, hissing, growling/snarling, grunting, and several different forms of meowing. Their body language, including position of ears and tail, relaxation of the whole body, and kneading of the paws, are all indicators of mood. The tail and ears are particularly important social signal mechanisms in cats. A raised tail indicates a friendly greeting, and flattened ears indicate hostility. Tail-raising also indicates the cat's position in the group's social hierarchy, with dominant individuals raising their tails less often than subordinate ones. Feral cats are generally silent.: 208 Nose-to-nose touching is also a common greeting and may be followed by social grooming, which is solicited by one of the cats raising and tilting its head.
Purring may have developed as an evolutionary advantage as a signaling mechanism of reassurance between mother cats and nursing kittens, who are thought to use it as a care-soliciting signal. Post-nursing cats also often purr as a sign of contentment: when being petted, becoming relaxed, or eating. Even though purring is popularly interpreted as indicative of pleasure, it has been recorded in a wide variety of circumstances, most of which involve physical contact between the cat and another, presumably trusted individual. Some cats have been observed to purr continuously when chronically ill or in apparent pain.
The exact mechanism by which cats purr has long been elusive, but it has been proposed that purring is generated via a series of sudden build-ups and releases of pressure as the glottis is opened and closed, which causes the vocal folds to separate forcefully. The laryngeal muscles in control of the glottis are thought to be driven by a neural oscillator which generates a cycle of contraction and release every 30–40 milliseconds (giving a frequency of 33 to 25 Hz).
Domestic cats observed in a rescue facility have total of 276 distinct facial expressions based on 26 different facial movements; each facial expression corresponds to different social functions that are likely influenced by domestication.
Grooming
Cats are known for spending considerable amounts of time licking their coats to keep them clean. The cat's tongue has backward-facing spines about 500 μm long, which are called papillae. These contain keratin which makes them rigid so the papillae act like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about 2–3 cm (0.79–1.18 in) long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut, as well as regular grooming of the coat with a comb or stiff brush.
Fighting
Among domestic cats, males are more likely to fight than females. Among feral cats, the most common reason for cat fighting is competition between two males to mate with a female. In such cases, most fights are won by the heavier male. Another common reason for fighting in domestic cats is the difficulty of establishing territories within a small home. Female cats also fight over territory or to defend their kittens. Neutering will decrease or eliminate this behavior in many cases, suggesting that the behavior is linked to sex hormones.
When cats become aggressive, they try to make themselves appear larger and more threatening by raising their fur, arching their backs, turning sideways and hissing or spitting. Often, the ears are pointed down and back to avoid damage to the inner ear and potentially listen for any changes behind them while focused forward. Cats may also vocalize loudly and bare their teeth in an effort to further intimidate their opponents. Fights usually consist of grappling and delivering powerful slaps to the face and body with the forepaws as well as bites. Cats also throw themselves to the ground in a defensive posture to rake their opponent's belly with their powerful hind legs.
Serious damage is rare, as the fights are usually short in duration, with the loser running away with little more than a few scratches to the face and ears. Fights for mating rights are typically more severe and injuries may include deep puncture wounds and lacerations. Normally, serious injuries from fighting are limited to infections of scratches and bites, though these can occasionally kill cats if untreated. In addition, bites are probably the main route of transmission of feline immunodeficiency virus. Sexually active males are usually involved in many fights during their lives, and often have decidedly battered faces with obvious scars and cuts to their ears and nose. Cats are willing to threaten animals larger than them to defend their territory, such as dogs and foxes.
Hunting and feeding
See also: Cat food
The shape and structure of cats' cheeks is insufficient to allow them to take in liquids using suction. Therefore, when drinking they lap with the tongue to draw liquid upward into their mouths. Lapping at a rate of four times a second, the cat touches the smooth tip of its tongue to the surface of the water, and quickly retracts it like a corkscrew, drawing water upward.
Feral cats and free-fed house cats consume several small meals in a day. The frequency and size of meals varies between individuals. They select food based on its temperature, smell and texture; they dislike chilled foods and respond most strongly to moist foods rich in amino acids, which are similar to meat. Cats reject novel flavors (a response termed neophobia) and learn quickly to avoid foods that have tasted unpleasant in the past. It is also a common misconception that cats like milk/cream, as they tend to avoid sweet food and milk. Most adult cats are lactose intolerant; the sugar in milk is not easily digested and may cause soft stools or diarrhea. Some also develop odd eating habits and like to eat or chew on things like wool, plastic, cables, paper, string, aluminum foil, or even coal. This condition, pica, can threaten their health, depending on the amount and toxicity of the items eaten.
Cats hunt small prey, primarily birds and rodents, and are often used as a form of pest control. Other common small creatures such as lizards and snakes may also become prey. Cats use two hunting strategies, either stalking prey actively, or waiting in ambush until an animal comes close enough to be captured. The strategy used depends on the prey species in the area, with cats waiting in ambush outside burrows, but tending to actively stalk birds.: 153 Domestic cats are a major predator of wildlife in the United States, killing an estimated 1.3 to 4.0 billion birds and 6.3 to 22.3 billion mammals annually.
Certain species appear more susceptible than others; in one English village, for example, 30% of house sparrow mortality was linked to the domestic cat. In the recovery of ringed robins (Erithacus rubecula) and dunnocks (Prunella modularis) in Britain, 31% of deaths were a result of cat predation. In parts of North America, the presence of larger carnivores such as coyotes which prey on cats and other small predators reduces the effect of predation by cats and other small predators such as opossums and raccoons on bird numbers and variety.
Perhaps the best-known element of cats' hunting behavior, which is commonly misunderstood and often appalls cat owners because it looks like torture, is that cats often appear to "play" with prey by releasing and recapturing it. This cat and mouse behavior is due to an instinctive imperative to ensure that the prey is weak enough to be killed without endangering the cat.
Another poorly understood element of cat hunting behavior is the presentation of prey to human guardians. One explanation is that cats adopt humans into their social group and share excess kill with others in the group according to the dominance hierarchy, in which humans are reacted to as if they are at or near the top. Another explanation is that they attempt to teach their guardians to hunt or to help their human as if feeding "an elderly cat, or an inept kitten". This hypothesis is inconsistent with the fact that male cats also bring home prey, despite males having negligible involvement in raising kittens.:
Play
Main article: Cat play and toys
Domestic cats, especially young kittens, are known for their love of play. This behavior mimics hunting and is important in helping kittens learn to stalk, capture, and kill prey. Cats also engage in play fighting, with each other and with humans. This behavior may be a way for cats to practice the skills needed for real combat, and might also reduce any fear they associate with launching attacks on other animals.
Cats also tend to play with toys more when they are hungry. Owing to the close similarity between play and hunting, cats prefer to play with objects that resemble prey, such as small furry toys that move rapidly, but rapidly lose interest. They become habituated to a toy they have played with before. String is often used as a toy, but if it is eaten, it can become caught at the base of the cat's tongue and then move into the intestines, a medical emergency which can cause serious illness, even death. Owing to the risks posed by cats eating string, it is sometimes replaced with a laser pointer's dot, which cats may chase.
Reproduction
See also: Kitten
The cat secretes and perceives pheromones. Female cats, called queens, are polyestrous with several estrus cycles during a year, lasting usually 21 days. They are usually ready to mate between early February and August in northern temperate zones and throughout the year in equatorial regions.
Several males, called tomcats, are attracted to a female in heat. They fight over her, and the victor wins the right to mate. At first, the female rejects the male, but eventually, the female allows the male to mate. The female utters a loud yowl as the male pulls out of her because a male cat's penis has a band of about 120–150 backward-pointing penile spines, which are about 1 mm (0.039 in) long; upon withdrawal of the penis, the spines may provide the female with increased sexual stimulation, which acts to induce ovulation.
After mating, the female cleans her vulva thoroughly. If a male attempts to mate with her at this point, the female attacks him. After about 20 to 30 minutes, once the female is finished grooming, the cycle will repeat. Because ovulation is not always triggered by a single mating, females may not be impregnated by the first male with which they mate. Furthermore, cats are superfecund; that is, a female may mate with more than one male when she is in heat, with the result that different kittens in a litter may have different fathers.
The morula forms 124 hours after conception. At 148 hours, early blastocysts form. At 10–12 days, implantation occurs. The gestation of queens lasts between 64 and 67 days, with an average of 65 days.
Data on the reproductive capacity of more than 2,300 free-ranging queens were collected during a study between May 1998 and October 2000. They had one to six kittens per litter, with an average of three kittens. They produced a mean of 1.4 litters per year, but a maximum of three litters in a year. Of 169 kittens, 127 died before they were six months old due to a trauma caused in most cases by dog attacks and road accidents. The first litter is usually smaller than subsequent litters. Kittens are weaned between six and seven weeks of age. Queens normally reach sexual maturity at 5–10 months, and males at 5–7 months. This varies depending on breed. Kittens reach puberty at the age of 9–10 months.
Cats are ready to go to new homes at about 12 weeks of age, when they are ready to leave their mother. They can be surgically sterilized (spayed or castrated) as early as seven weeks to limit unwanted reproduction. This surgery also prevents undesirable sex-related behavior, such as aggression, territory marking (spraying urine) in males and yowling (calling) in females. Traditionally, this surgery was performed at around six to nine months of age, but it is increasingly being performed before puberty, at about three to six months. In the United States, about 80% of household cats are neutered.
Lifespan and health
Main articles: Cat health and Aging in cats
The average lifespan of pet cats has risen in recent decades. In the early 1980s, it was about seven years,: 33 rising to 9.4 years in 1995: 33 and an average of about 13 years as of 2014 and 2023. Some cats have been reported as surviving into their 30s, with the oldest known cat dying at a verified age of 38.
Neutering increases life expectancy: one study found castrated male cats live twice as long as intact males, while spayed female cats live 62% longer than intact females.: 35 Having a cat neutered confers health benefits, because castrated males cannot develop testicular cancer, spayed females cannot develop uterine or ovarian cancer, and both have a reduced risk of mammary cancer.
Disease
Main article: List of feline diseases
About 250 heritable genetic disorders have been identified in cats, many similar to human inborn errors of metabolism. The high level of similarity among the metabolism of mammals allows many of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats as animal models in the study of the human diseases. Diseases affecting domestic cats include acute infections, parasitic infestations, injuries, and chronic diseases such as kidney disease, thyroid disease, and arthritis. Vaccinations are available for many infectious diseases, as are treatments to eliminate parasites such as worms, ticks, and fleas.
Ecology
Habitats
The domestic cat is a cosmopolitan species and occurs across much of the world. It is adaptable and now present on all continents except Antarctica, and on 118 of the 131 main groups of islands, even on the isolated Kerguelen Islands. Due to its ability to thrive in almost any terrestrial habitat, it is among the world's most invasive species. It lives on small islands with no human inhabitants. Feral cats can live in forests, grasslands, tundra, coastal areas, agricultural land, scrublands, urban areas, and wetlands.
The unwantedness that leads to the domestic cat being treated as an invasive species is twofold. On one hand, as it is little altered from the wildcat, it can readily interbreed with the wildcat. This hybridization poses a danger to the genetic distinctiveness of some wildcat populations, particularly in Scotland and Hungary, possibly also the Iberian Peninsula, and where protected natural areas are close to human-dominated landscapes, such as Kruger National Park in South Africa. However, its introduction to places where no native felines are present also contributes to the decline of native species.
Ferality
Main article: Feral cat
Feral cats are domestic cats that were born in or have reverted to a wild state. They are unfamiliar with and wary of humans and roam freely in urban and rural areas. The numbers of feral cats is not known, but estimates of the United States feral population range from 25 to 60 million. Feral cats may live alone, but most are found in large colonies, which occupy a specific territory and are usually associated with a source of food. Famous feral cat colonies are found in Rome around the Colosseum and Forum Romanum, with cats at some of these sites being fed and given medical attention by volunteers.
Public attitudes toward feral cats vary widely, from seeing them as free-ranging pets to regarding them as vermin.
Some feral cats can be successfully socialized and 're-tamed' for adoption; young cats, especially kittens and cats that have had prior experience and contact with humans are the most receptive to these efforts.
Impact on wildlife
Main article: Cat predation on wildlife
On islands, birds can contribute as much as 60% of a cat's diet. In nearly all cases, the cat cannot be identified as the sole cause for reducing the numbers of island birds, and in some instances, eradication of cats has caused a "mesopredator release" effect; where the suppression of top carnivores creates an abundance of smaller predators that cause a severe decline in their shared prey. Domestic cats are a contributing factor to the decline of many species, a factor that has ultimately led, in some cases, to extinction. The South Island piopio, Chatham rail, and the New Zealand merganser are a few from a long list, with the most extreme case being the flightless Lyall's wren, which was driven to extinction only a few years after its discovery. One feral cat in New Zealand killed 102 New Zealand lesser short-tailed bats in seven days. In the US, feral and free-ranging domestic cats kill an estimated 6.3 – 22.3 billion mammals annually.
In Australia, the impact of cats on mammal populations is even greater than the impact of habitat loss. More than one million reptiles are killed by feral cats each day, representing 258 species. Cats have contributed to the extinction of the Navassa curly-tailed lizard and Chioninia coctei.
Interaction with humans
Main article: Human interaction with cats
Cats are common pets throughout the world, and their worldwide population as of 2007 exceeded 500 million. As of 2017, the domestic cat was the second most popular pet in the United States, with 95.6 million cats owned and around 42 million households owning at least one cat. In the United Kingdom, 26% of adults have a cat, with an estimated population of 10.9 million pet cats as of 2020. As of 2021, there were an estimated 220 million owned and 480 million stray cats in the world.
Cats have been used for millennia to control rodents, notably around grain stores and aboard ships, and both uses extend to the present day.
As well as being kept as pets, cats are also used in the international fur trade and leather industries for making coats, hats, blankets, stuffed toys, shoes, gloves, and musical instruments. About 24 cats are needed to make a cat-fur coat. This use has been outlawed in the United States since 2000 and in the European Union (as well as the United Kingdom) since 2007.
Cat pelts have been used for superstitious purposes as part of the practice of witchcraft, and are still made into blankets in Switzerland as traditional medicine thought to cure rheumatism.
A few attempts to build a cat census have been made over the years, both through associations or national and international organizations (such as that of the Canadian Federation of Humane Societies) and over the Internet, but such a task does not seem simple to achieve. General estimates for the global population of domestic cats range widely from anywhere between 200 million to 600 million. Walter Chandoha made his career photographing cats after his 1949 images of Loco, an especially charming stray taken in, were published around the world. He is reported to have photographed 90,000 cats during his career and maintained an archive of 225,000 images that he drew from for publications during his lifetime.
Shows
Main article: Cat show
A cat show is a judged event in which the owners of cats compete to win titles in various cat-registering organizations by entering their cats to be judged after a breed standard. It is often required that a cat must be healthy and vaccinated in order to participate in a cat show. Both pedigreed and non-purebred companion ("moggy") cats are admissible, although the rules differ depending on the organization. Competing cats are compared to the applicable breed standard, and assessed for temperament.
Infection
Main article: Feline zoonosis
Cats can be infected or infested with viruses, bacteria, fungus, protozoans, arthropods or worms that can transmit diseases to humans. In some cases, the cat exhibits no symptoms of the disease. The same disease can then become evident in a human. The likelihood that a person will become diseased depends on the age and immune status of the person. Humans who have cats living in their home or in close association are more likely to become infected. Others might also acquire infections from cat feces and parasites exiting the cat's body. Some of the infections of most concern include salmonella, cat-scratch disease and toxoplasmosis.
History and mythology
Main articles: Cultural depictions of cats and Cats in ancient Egypt
In ancient Egypt, cats were worshipped, and the goddess Bastet often depicted in cat form, sometimes taking on the war-like aspect of a lioness. The Greek historian Herodotus reported that killing a cat was forbidden, and when a household cat died, the entire family mourned and shaved their eyebrows. Families took their dead cats to the sacred city of Bubastis, where they were embalmed and buried in sacred repositories. Herodotus expressed astonishment at the domestic cats in Egypt, because he had only ever seen wildcats.
Ancient Greeks and Romans kept weasels as pets, which were seen as the ideal rodent-killers. The earliest unmistakable evidence of the Greeks having domestic cats comes from two coins from Magna Graecia dating to the mid-fifth century BC showing Iokastos and Phalanthos, the legendary founders of Rhegion and Taras respectively, playing with their pet cats. The usual ancient Greek word for 'cat' was ailouros, meaning 'thing with the waving tail'. Cats are rarely mentioned in ancient Greek literature. Aristotle remarked in his History of Animals that "female cats are naturally lecherous." The Greeks later syncretized their own goddess Artemis with the Egyptian goddess Bastet, adopting Bastet's associations with cats and ascribing them to Artemis. In Ovid's Metamorphoses, when the deities flee to Egypt and take animal forms, the goddess Diana turns into a cat.
Cats eventually displaced weasels as the pest control of choice because they were more pleasant to have around the house and were more enthusiastic hunters of mice. During the Middle Ages, many of Artemis's associations with cats were grafted onto the Virgin Mary. Cats are often shown in icons of Annunciation and of the Holy Family and, according to Italian folklore, on the same night that Mary gave birth to Jesus, a cat in Bethlehem gave birth to a kitten. Domestic cats were spread throughout much of the rest of the world during the Age of Discovery, as ships' cats were carried on sailing ships to control shipboard rodents and as good-luck charms.
Several ancient religions believed cats are exalted souls, companions or guides for humans, that are all-knowing but mute so they cannot influence decisions made by humans. In Japan, the maneki neko cat is a symbol of good fortune. In Norse mythology, Freyja, the goddess of love, beauty, and fertility, is depicted as riding a chariot drawn by cats. In Jewish legend, the first cat was living in the house of the first man Adam as a pet that got rid of mice. The cat was once partnering with the first dog before the latter broke an oath they had made which resulted in enmity between the descendants of these two animals. It is also written that neither cats nor foxes are represented in the water, while every other animal has an incarnation species in the water. Although no species are sacred in Islam, cats are revered by Muslims. Some Western writers have stated Muhammad had a favorite cat, Muezza. He is reported to have loved cats so much, "he would do without his cloak rather than disturb one that was sleeping on it". The story has no origin in early Muslim writers, and seems to confuse a story of a later Sufi saint, Ahmed ar-Rifa'i, centuries after Muhammad. One of the companions of Muhammad was known as Abu Hurayrah ("father of the kitten"), in reference to his documented affection to cats.
Superstitions and rituals
Many cultures have negative superstitions about cats. An example would be the belief that encountering a black cat ("crossing one's path") leads to bad luck, or that cats are witches' familiars used to augment a witch's powers and skills. The killing of cats in Medieval Ypres, Belgium, is commemorated in the innocuous present-day Kattenstoet (cat parade). In mid-16th century France, cats would be burnt alive as a form of entertainment, particularly during midsummer festivals. According to Norman Davies, the assembled people "shrieked with laughter as the animals, howling with pain, were singed, roasted, and finally carbonized". The remaining ashes were sometimes taken back home by the people for good luck.
According to a myth in many cultures, cats have multiple lives. In many countries, they are believed to have nine lives, but in Italy, Germany, Greece, Brazil and some Spanish-speaking regions, they are said to have seven lives, while in Arabic traditions, the number of lives is six. An early mention of the myth can be found in John Heywood's The Proverbs of John Heywood (1546)
Husband, (quoth she), ye studie, be merrie now,
And even as ye thinke now, so come to yow.
Nay not so, (quoth he), for my thought to tell right,
I thinke how you lay groning, wife, all last night.
Husband, a groning horse and a groning wife
Never faile their master, (quoth she), for my life.
No wife, a woman hath nine lives like a cat.
The myth is attributed to the natural suppleness and swiftness cats exhibit to escape life-threatening situations. Also lending credence to this myth is the fact that falling cats often land on their feet, using an instinctive righting reflex to twist their bodies around. Nonetheless, cats can still be injured or killed by a high fall.
This is the foundation for some other modules I'm building... have good working prototypes of a keyboard and an Ondes Martenot style controller for it so far.
I've added inputs for both oscillators so it can be played more like a normal musical instrument... 90% of the time I'm using the Ondes Martenot controller through oscillator 1, but I also have a neat little keyboard I made that gets some use. I'd like to make a tannerin/ribbon controller for it, but am having a lot of trouble finding something* with the proper resistance. For my next trick, I'm doing a CV input for oscillator 2 and an optical sequencer for oscillator 1. Thanks to Hack-A-Day for some of the mods and Diet Coke and Penguin Mints for the rest.
Audio sample using the Ondes Martenot module
Another sample using the Ondes Martenot module
A sample using a keyboard module
* finding something means scouring my junk-filled guitar store slash laboratory... I could probably do the static strap controller if I really worked at it, but the ondes controller is so freakin' cool that I'm happy for now.
soundcloud.com/toxi/sets/granular-synthesis
Watch in highres! Spectrum of an image to create an audio sequence of 2048 grains. See description in set & earlier tests...
Needs your free vote of support at: goo.gl/heBmZ7
With enough votes, it could be made into an actual set by LEGO!
Also, please check out my Minimoog models at: goo.gl/iucWKS
AND
the Prism & Spectrum at: goo.gl/pFTr3v
"So if we draw a line between the center of thrust and the the coaxial oscillator, we see it should be at least 12 centimeters below specs, or it will dampen the ion conensators..."
"Labba-Labba"
"What, sorry?"
"I an I thinks you labba-mouth from Babylon - I an I gonna bun whole heap a herb. Join me?"
[transcript from design session 122, GHL Bhang IV systems engineering department]
Preserved by České dráhy T478.1001 [751.001] is seen pausing at Hrušovany nad Jevišovkou before the run down the small but now mothballed branch to Hevlín (at around 10 kph) on the Austrian border whilst working R10064 from Rakšice – Hevlín alongside is 742 334. Friday 7th July 2017.
This was part of Grumpy Tours “The Oslavany Oscillator” which ran from Brno to Brno via Oslavany, Hevlín, Kúty and Hustopeče u Brna.
Five drone voices whose pitch can be tuned by the massive knob at the bottom or by an LDR at the top. The medium size knob is the speed of essentially an LFO that sends a little "blip" to the volume of the voice below. These create a fun poly-rhythm/phasing between the five voices. The speed of this LFO can also respond to an LDR at the top.
The whole thing is housed in some beautiful walnut, finished in Danish oil with a plywood face.
A video youtu.be/9mdVZb-LE1U
Oscar and Sarah gave me a few minutes to put some of the finishing touches on the 4SQRP HF Test Set I assembled a few months ago. It's really a nice tool. I will use the frequency counter and crystal oscillator the most, probably. But there are lots of other tools built into this nifty little outfit.
RF EHT supply in development. Oscillator valve is a 6M5. This was changed to 6AQ5. Rectifier is 6X2.
vendor link:
midnightdesignsolutions.com/dds60/index.html
the presentation, labeling and packing of this earns an A+ ! I've never gotton such a well labelled kit before; not even from heathkit ;)
photo with the instructions (color, printed!):
www.flickr.com/photos/linux-works/6979839745/in/photostream
"RF: its what's for dinner!"