The cat is a genus of highly sophisticated, intelligent and paradoxical carnivorous mammals (Felidae or Felis). The genus includes the most highly specialized of the carnivores. The mechanism by which the claws are retracted (in some species) is highly sophisticated, and the claws are extremely sharp and powerful weapons. The teeth number thirty, and are used to tear meat which is then swallowed without mastication. The tongue is rough and functions as a rasp.
Cats have been domesticated since the earliest of times, and were considered sacred to the goddess Bast by the ancient Egyptians. Generally people either like cats and dislike dogs, or dislike cats and like dogs, reflecting the two very different, opposing natures of the two animals. Where as dogs are loyal, trainable and generally giving, cats are highly independent. Coming and going as they see fit, and often giving the impression that the owner of a pet cat is actually the pet himself! It is this independence that makes cats so attractive as a pet to many people.
Cats are renowned for their intelligence, and sensitivity, but are also completely daft at times, behaving not unlike a small child playing with pieces of string or chasing their tail. At times affectionate, and at others aloof and arrogant, but always mysterious and amusing as was reflected in the very perceptive American 'Fat Freddy's Cat' comic books which were published during the 1970s and 1980s. Almost all species of cat purr, though not tigers, and the sound of purring has been found to trigger the healing process in the cats bones, and also strengthen human bones. It is thought that cats purr for a number of reasons, most obviously as an expression of contentment, and also as a method of self-healing, which may account for their remarkable resilience to injury, being able to fall great distances and survive.
Cats, particularly tigers and Siamese, do talk to each other, and to any human prepared to listen, communicating in numerous growls and meows, though as yet their language is not understood.
David Hume was a British historian and philosopher. He was born in 1711 at Edinburgh and died in 1776. He was destined for the law, but was drawn away by his love of literature and philosophy; and retired to France, where during three years of quiet and studious life he composed his Treatise upon Human Nature. The work was published at London in 1738, but, in his own words, 'fell dead-born from the press.' His next work, Essays, Moral, Political, and Literary (published at Edinburgh, in 1742), met with a better reception.
In 1745 he became companion to the insane Marquis of Annandale; and he accompanied General Sinclair in 1746 and 1747 in his expedition against France and in a military embassy to Vienna and Turin. He now published a recasting of his Treatise upon Human .Nature, under the title of an Inquiry Concerning the Human Understanding (1747). In 1752 he published his Political Discourses, which were well received, and his Inquiry Concerning the Principles of Morals. The same year he obtained the appointment of librarian of the Advocates' Library at Edinburgh, and began to write his history of England, of which the first volume appeared in 1754. It was, like most of the succeeding volumes, severely attacked both for its religious and political tendencies; but, in spite of adverse criticism, his History of England, after its completion in 1761, was recognized as a standard work. Its merits are chiefly clearness and force of narrative and philosophical breadth of view in the judgment of men and events.
In 1763 he accepted an invitation from the Earl of Hertford, then proceeding as ambassador to Paris, to accompany him, and was enthusiastically received by Parisian circles in his character of philosopher and historian. After the departure of LordHertford in 1756, he remained as charge d'affaires, and returned to England in 1766, bringing with him Rousseau, for whom he procured a pension and a retreat in Derbyshire. But the morbid sensitivity of Rousseau brought about a disagreement which put an end to the friendship.
In 1767 he was appointed under-secretary of state, a post which be held until 1769, when he retired to Edinburgh. Here he lived until his death on August the 25th, 1776. As a philosopher, in which quality his reputation is perhaps greatest, David Hume's acute sceptical intellect did great service by directing research to the precise character of the fundamental conceptions on which our knowledge and our beliefs are based. His acute negative criticism of these conceptions (e.g. his reduction of the ideas of personal identity, conscience, causality, to mere effects of association) compelled philosophy either to come to a dead halt or to find, as Kant did, a new and profounder view of the nature of human reason. Research David Hume
Coeliac disease is a chronic intestinal disorder occuring in young children caused by sensitivity to the proteingliadin contained in the gluten of cereals.
Coeliac disease is characterised by distention of the abdomen and frothy, pale, foul-smelling stools. Research Coeliac Disease
Conjunctivitis is a bacterial or viral infection of the conjunctiva of the eye. It may also be caused by sensitivity to certain cosmetics or drugs. It is a very common complaint characterised by a gritty and burning sensation of the eye and discomfort when moving the eye. The sclera becomes red and irritated and the eyes have a sticky, yellow discharge. In most cases, both eyes become inflamed. The infection is spread easily through towels or wash-cloths. Research Conjunctivitis
Dyspraxia (also known as Clumsy Child Syndrome, Developmental Coordination Disorder (DCD), Perceptuo-motor Dysfunction, Minimal Brain Dysfunction and Motor Learning Difficulty) is a believed (but unproven) immaturity of the brain though to result in messages not being properly transmitted to the body. It is believed by advocates of the theory to affect at least 2% of the British population in varying degrees of severity with 70% of those affected being male. Symptoms of dyspraxia may include some of: clumsiness; poor posture; awkward walking; confusion over which hand to use; difficulties in throwing or catching a ball; sensitivity to touch; finding some clothes uncomfortable; poor short term memory; poor body awareness; difficulties with reading and writing; inability to hold a pen or pencil properly; poor sense of direction; lack of balance; slow development; inability to answer simple questions even though they know the answer; speech problems, slow to learn to speak or incoherent speech; phobias and obsessive behaviour;
impatience; intolerance to having hair or teeth brushed, nails and hair cut; plasters too uncomfortable to wear. Though advocates of dyspraxia claim that different sufferers will suffer various symptoms, not all suffering all or even the same symptoms. Older sufferers typically display signs of very immature behaviour. Recent discoveries have found that often sufferers of dyspraxia hallucinate taste sensations when speaking, that is pronouncing different words gives rise to different tastes in the mouth. The Bronte sisters were thought to suffer from dyspraxia, and often sufferers excell in language and literature, while facing severe difficulties with inter-personal relationships and motor coordination. Research Dyspraxia
The pituitary gland (or hypophysis),is a gland within the brain concerned with regulating growth and regulating other ductless glands. The pituitary gland , consists of three lobes, the anterior lobe, the intermediate lobe, which in primates is present for only a short part of the life span, and the posterior lobe. It is situated at the base of the brain and has been called the master controlling gland of the body. The anterior and the posterior lobes of the pituitary secrete different hormones. The anterior lobe secretes various hormones that stimulate the function of other endocrine glands, for example, adrenocorticotropic hormone, or ACTH, which stimulates the adrenal cortex; thyroid- stimulating hormone, or thyrotropin, known as TSH; follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which stimulate the sex glands; and prolactin, which, with other special hormones, influences milk production of the mammary gland.
In addition, the anterior pituitary is the source of growthhormone, also called somatotropin, which promotes the development of body tissues, particularly of bone matrix and muscle, and influences carbohydrate metabolism. The anterior pituitary also secretes a hormone called melanocyte-stimulating hormone, which regulates the intensity of pigmentation in pigmented cells. In the 1970s scientists found that the anterior pituitary also produces substances called endorphins. These are peptides that act on the peripheral and central nervous systems to reduce sensitivity to pain. The hypothalamus, secretes an antidiuretic hormone named vasopressin, which is stored in the posterior lobe of the pituitary gland. The posterior lobe of the pituitary also stores another hormone secreted by the hypothalamus. This hormone, known as oxytocin, stimulates muscular contractions, especially of the uterus, and ejection of milk from lactating mammary glands. Not long ago it was found that secretion of three anterior pituitary hormones is under regulation of the hypothalamus: thyrotropin secretion is stimulated by thyrotropin-releasing factor (TRF), and luteinizing- hormone secretion by luteinizing-hormone releasing hormone (LHRH). Release of growthhormone is inhibited by somatostatin, which is also made by the pancreas. Research Pituitary gland
Detecting set L4A1 was the British Army designation for the Plessey P6/2 Metal detector range.
The P6/2 equipment consisted of a waterproof electronic unit and a set of operator-interchangeable waterproof probes. The operating mode was pulsed induction. Target detection was indicated audibly by a loudspeaker or plug-in earphone(s). Switched sensitivity and response times were provided. Power was supplied from internal batteries or an external source via an adaptor. An in-built battery check was provided. The function switch, loudspeaker, probe and earphone sockets wee located on a control panel at-the top of the electronic unit. The electronic unit was carried in a slung webbing haversack for manpack operation.
Four types of probe were provided as standard, each for a specific purpose. A connection cable terminated in a quick release plug is integral with each probe.
P6A/2 was a tubular ferrite probe suitable for searches in bushes, streams and rugged urban and rural environments.
P6E/2 Open Loop Probe was a lightweight probe, for ground search applications.
P6F/2 was a short robust probe for general searches in restricted environments.
P6G/2 was a light easy-to-use probe designed for the searching of persons.
Plessey could also supply special probes that could be designed for particular applications e.g. the P6C/2 sledge probe.
The P6/2 equipment was designed to perform over the frequency range 50 to 500MHz. When fitted with a P6A/2 or P6F/2 probe and an MDA7/2 earpiece the P6/2 was capable of operating within four metres of a 1W, handheld radio transmitter or within six metres of a vehicle-mounted 10W radio transmitter without malfunctioning, blocking, or causing interference to the receiver in the radio station.
Typical detection range for the P6E/2 Probe was approximately 220mm with a 2p coin or 250mm2 copper, 18 G and approximately 400mm with a pistol Research Detecting Set L4A1
Photography is the art, and sometimes business, of taking and also sometimes producing and printing photographs.
Early cameras operated upon the principle of allowing light reflected from a subject to fall upon a light-sensitive chemical impregnated plate, later plastic film. These plates or films were then treated with other chemicals to prevent further sensitivity to light, thereby fixing the image which was then printed. Later digital cameras evolved which used electronic light sensors to record the image in a binary digital file on a memory card.
If too much light is allowed in to the camera, the picture will be over exposed, and will look bright and indistinct. If not enough light is allowed in, the picture will be under exposed and will look dark and indistinct. It is less common for photographs to be over exposed, than under exposed.
Light is allowed in to the camera to the photograph plate, film or sensor through a quickly opening and closing door called the shutter. The size of the hole which is revealed by the shutter is known as the aperture, and is measured in F-Stops, such as F1.8, F4.5, F11 etc. Where, confusingly, the larger the F number the smaller the aperture is. Thus, F1.8 is quite a large aperture, and F11 is fairly small. A larger aperture, represented by a smaller F number, lets in more light than a smaller aperture.
The length of time for which the shutter remains open, letting light in through the aperture is often referred to as the shutter speed, and is measured in fractions of a second. Thus, a shutter speed of 500 implies that the aperture will be open for 1/500th of a second, while a shutter speed of 125 implies that the aperture will be open for 1/125th of a second. The longer the aperture remains open, the more light will enter.
How quickly the photographic plate, film or sensor reacts to the light reaching it through the aperture is known as the sensitivity of the plate, film or sensor and is measured in ISO or ASA units. The larger the ISO value, the quicker the plate, film or sensor will react to the light. Thus, a sensitivity of ASA or ISO 100 will react slower than a sensitivity of 200 or 400.
The aperture size, shutter speed and sensitivity, work together to determine the level of exposure that occurs when a picture is taken. Automatic camera settings will set these three values for you, so that the picture is properly exposed, and if it can not be properly exposed, will warn you. However, there are other effects connected with each of these three settings.
The higher the sensitivity of the photographic plate, film or sensor, the more grainy or noisy the photograph will be. Therefore, using the lowest possible sensitivity will give the best possible quality for the photograph. In order to use a low sensitivity, the subject must be as brightly lit as possible. For example a subject in bright sunshine or lit by powerful lamps or the use of a cameraflash gun.
The camera's aperture size governs the depth of the photograph. The smaller the aperture is, the deeper the field of focus. Using a large aperture size will result in only the subject being in focus, objects behind and in front of the subject will be blurred. Using a small aperture will allow objects behind and in front of the subject to also be in focus. The smaller the aperture size, the further behind and in front of the subject objects will remain in focus, and by extension the easier it will be to focus upon the subject.
The most noticeable effect of the shutter speed is in reducing motion blur and camerashake. When holding a camera, particularly one with a long lens every one will quiver their hand to a greater or lesser degree. When using a zoom lens, this quivering or camerashake is much more noticeable than when using a shorter or wider angle lens. If the camera is moved, even slightly while the shutter is open, the picture will be blurred. The more the camera moves while the shutter is open, the more blurring will occur. By using a fast shutter speed, the shutter is open for less time and as such less movement affect the photograph. Similarly, if the subject being photographed moves while the image is being taken, the resulting photograph will be blurred. Using a fast shutter speed of 1/500th of a second or faster enables photographs to be taken of action shots, such as footballers in mid-movement or in the air while heading the ball. The subject's movement being slower than the speed of the shutter opening and closing which appears to freeze the moment in time.
The best way to reduce camerashake is to use a tripod. If you can not use a tripod, try resting the camera on a firm surface, such as a wall, fence post or tree. It can not be over emphasised that using a tripod will result in better photographs as every one quivers ever so slightly when taking photographs. Even activating the shutter release on the camera can slightly jar the camera. To overcome this, many photographers use a camera with automatic frame advance or sequential shooting, whereby after activating the shutter release the camera takes multiple photographs until the shutter release mechanism is released. In this way, three images may be taken automatically, the first and last will often suffer from slight camerashake due to the action of operating the shutter release mechanism, while the second image will not. Research Photography
In physics, photometry is the measurement of the luminous intensity of a light source, or the amount of luminous flux falling upon a surface from such a source. Photometry is important in photography , astronomy, and illumination engineering. Instruments used for photometry are called photometers. Light waves stimulate the humaneye in different degrees, depending on the wavelength of the light. Because it is difficult to make an instrument with the same sensitivity for different wavelengths as the humaneye, many photometers use a human observer. Photoelectric photometers need special collared filters to make them respond like the humaneye. Instruments that measure radiant energy instead of light are called radiometers, and must be made equally sensitive to all wavelengths. The intensity of a light source is measured in candle power, usually by comparing the source with a standard source provided by the National Bureau of Standards. The known and unknown sources illuminate portions of a window surface side by side, and their distances are adjusted until the illumination on the surface is the same. The relative intensity is then calculated from the inverse square law. Research Photometry
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Cat
