History of the X-Ray

History of the X-Ray All light and radio waves belong to the electromagnetic spectrum and are all considered different types of electromagnetic waves, including: microwaves and infrared bands whose waves are longer than those of visible light (between radio and the visible)and UV, EUV, X-rays, and g-rays (gamma rays) with shorter wavelengths. The electromagnetic nature of x-rays became evident when it was found that crystals bent their path in the same way as gratings bent visible light: the orderly rows of atoms in the crystal acted like the grooves of a grating. Medical X-rays X-rays are capable of penetrating some thickness of matter. Medical x-rays are produced by letting a stream of fast electrons come to a sudden stop at a metal plate; it is believed that X-rays emitted by the Sun or stars also come from fast electrons. The images produced by X-rays are due to the different absorption rates of different tissues. Calcium in bones absorbs X-rays the most, so bones look white on a film recording of the X-ray image, called a radiograph. Fat and other soft tissues absorb less and look gray. Air absorbs the least, so lungs look black on a radiograph. Wilhelm Conrad Rà ¶ntgen - First X-ray On 8 Nov 1895, Wilhelm Conrad Rà ¶ntgen (accidentally) discovered an image cast from his cathode ray generator, projected far beyond the possible range of the cathode rays (now known as an electron beam). Further investigation showed that the rays were generated at the point of contact of the cathode ray beam on the interior of the vacuum tube, that they were not deflected by magnetic fields, and they penetrated many kinds of matter. A week after his discovery, Rontgen took an X-ray photograph of his wifes hand which clearly revealed her wedding ring and her bones. The photograph electrified the general public and aroused great scientific interest in the new form of radiation. Rà ¶ntgen named the new form of radiation X-radiation (X standing for Unknown). Hence the term X-rays (also referred as Rà ¶ntgen rays, though this term is unusual outside of Germany). William Coolidge X-Ray Tube William Coolidge invented the X-ray tube popularly called the Coolidge tube. His invention revolutionized the generation of X-rays and is the model upon which all X-ray tubes for medical applications are based. Other inventions of Coolidge: invention of ductile tungsten A breakthrough in tungsten applications was made by W. D. Coolidge in 1903. Coolidge succeeded in preparing a ductile tungsten wire by doping tungsten oxide before reduction. The resulting metal powder was pressed, sintered and forged to thin rods. A Very thin wire was then drawn from these rods. This was the beginning of tungsten powder metallurgy, which was instrumental in the rapid development of the lamp industry - International Tungsten Industry Association (ITIA) A computed tomography scan or CAT-scan uses  X-rays  to create images of the body.  However, a radiograph (x-ray) and a  CAT-scan  show different types of information. An x-ray is a two-dimensional picture and a CAT-scan is three-dimensional. By imaging and looking at several three-dimensional slices of a body (like slices of bread) a doctor could not only tell if a tumor is  present but roughly how deep it is in the body. These slices are no less than 3-5 mm apart. The newer spiral (also called helical) CAT-scan takes continuous pictures of the body in a spiral  motion so that there are no gaps in the pictures collected. A CAT-scan can be three dimensional because the information about how much of the X-rays are passing through a body is collected not just on a flat piece of film, but on a computer. The data from a CAT-scan can then be computer-enhanced to be more sensitive than a plain radiograph. Inventor of the Cat-scan Robert Ledley was the inventor of CAT-Scans a diagnostic x-Ray system. Robert Ledley was granted patent #3,922,552 on November 25th in 1975 for a diagnostic X-ray systems also known as CAT-Scans.

Free Essays on Hotels

Within the hotel industry there are different classes which determine the price and the kind of people that stay there. You have you high end hotels such as Hilton, Sheraton and Wingate, and then you also have your lower end hotels such as Super Eight and Red Roof Inn. For my observations I chose to research the Wingate Inn and the Red Roof Inn, there are a few distinct difference between the two which let you know which is the more higher end hotel. The Wingate Inn focuses on trying to gain business from other businesses; they focus around making the lives of business travelers easier. The Wingate has 84 rooms, fitness center, and indoor pool, high speed internet connection in each room, a business center and many other things to make the business traveler’s life a lot easier. When it comes to Budgeting for advertising and marketing the Wingate had billboards and newspaper ads, but the most of their business and advertising comes from the internet. Out of the total revenue 3 1/2 – 4% go towards advertising order to find the best person for the job. Being a business oriented hotel, the main programs that they offer are conferences, in which are held by different companies in their conference rooms. They have a fitness center which is used by guest but do not offer any programs for that. They are always open to host a wedding or a reception though; it’s a nice change from the normal business conference. This differs from the Red Roof Inn, in that the Red Roof Inn does not offer have of the amenities that the Wingate does. The Wingate being a higher end hotel has an indoor pool, conference rooms, and has more disposable income to spend on things such as advertising and different programs to keep its clientele happy. When someone is chooseing a place to stay they normally choose on price and things that a hotel have to offer. But then other just chose a hotel because of where it is and how easy it will be to get back on the roa... Free Essays on Hotels Free Essays on Hotels Within the hotel industry there are different classes which determine the price and the kind of people that stay there. You have you high end hotels such as Hilton, Sheraton and Wingate, and then you also have your lower end hotels such as Super Eight and Red Roof Inn. For my observations I chose to research the Wingate Inn and the Red Roof Inn, there are a few distinct difference between the two which let you know which is the more higher end hotel. The Wingate Inn focuses on trying to gain business from other businesses; they focus around making the lives of business travelers easier. The Wingate has 84 rooms, fitness center, and indoor pool, high speed internet connection in each room, a business center and many other things to make the business traveler’s life a lot easier. When it comes to Budgeting for advertising and marketing the Wingate had billboards and newspaper ads, but the most of their business and advertising comes from the internet. Out of the total revenue 3 1/2 – 4% go towards advertising order to find the best person for the job. Being a business oriented hotel, the main programs that they offer are conferences, in which are held by different companies in their conference rooms. They have a fitness center which is used by guest but do not offer any programs for that. They are always open to host a wedding or a reception though; it’s a nice change from the normal business conference. This differs from the Red Roof Inn, in that the Red Roof Inn does not offer have of the amenities that the Wingate does. The Wingate being a higher end hotel has an indoor pool, conference rooms, and has more disposable income to spend on things such as advertising and different programs to keep its clientele happy. When someone is chooseing a place to stay they normally choose on price and things that a hotel have to offer. But then other just chose a hotel because of where it is and how easy it will be to get back on the roa...

Compare Vygotsky's and Feuersteins contributions to Educational Essay

Compare Vygotsky's and Feuersteins contributions to Educational Learning - Essay Example Building therefore on this base, Vygotsky developed a theory in which society and culture contribute to the learning process of children and is in large part responsible for their learning. Feuerstein's great contribution has usually been to operationalize the concepts propounded by Vygotsky. Such components as sociocultural mediation and the Zone of Proximal Development (ZPD), identified by Vygotsky, have been further developed and probed by the capable instruments created by Feuerstein for enhancement of mediated learning. The theories of social and cultural mediation as propounded by Vygotsky and Feuerstein will be explored in this essay. It will also consider the ZPD and the instruments that have been developed to enhance learning using these theories. Vygotsky argues that children develop higher levels of cognition through the mediation that occurs in a social context. Lower mental processes are genetic and instinctive; they come naturally to an individual. The higher mental processes, on the other hand, are definitive of a cognitive stage unique in man as a species through which he is able to distance himself from the world and, through the use of various symbols and in conjunction with other men, abstractly manipulate its contents to extract and develop his knowledge and understanding of them (Panofsky, 2003). Because of the meaning these higher mental functions have for society, and because they exist before (and independent of) the individual, they must be learned through mediation. This means that higher levels of cognition are necessarily mediated by society, and it is only once a lesson is learned on the societal level that it becomes internalised and manifests itself on a psychological level. Social agents of mediation ta ke a variety of forms and provide the learner with access to what has been given a variety of names ranging from psychological, to cultural or cognitive tools (Smagorinski). How a human person acts within a given society is dependent on the forms and qualities of interactions available to him as a model. If adequate mediation is provided, learning occurs; if not, learning suffers. This theory then goes on to describe the child and/or learner as limited in his or her ability to acquire knowledge when left on his own. What a child is able to perform when placed in a social setting is almost invariably more than that which he or she is able to do alone, and this additional capability gives the educator an idea of the child's potential (Salomon and Perkins, 1998). This potential (denoted by Vygotsky as the Zone of Proximal Development) cannot be realised, however, unless learning is mediated by another in a social setting. Feuerstein also advocated the theory of mediation in learning. He developed the cognitive map which denotes the dimensions of cognition, and contributed to the mediation theory by formulating an operation that delineates the different stages and participants in the mediation process. The Mediated Learning Experience (MLE) he defined as "The quality of interaction directed towards ensuring meaningful learning by parents, teachers, caregivers and peers, interposed between the child and the stimuli they receive" (Feuerstein). It was his idea that these social mediators