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| So you're into sci fi? But what about sci fact? Sometimes fact is stranger than fiction... Each month our very own Voyager Science Queen* will bring you interesting, quirky and downright bizarre tasty morsels from the world of science. And its all completely, totally, 100% true! August Sci-Facts |
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Twisting the Light On the forum, I was asked about a problem experienced with some photographs, where there appears to be a floating spot of light in the photo. It was an intriguing question that involved a fair amount of research…and here is the best answer that I could discover! The main 'eye' of a camera is the glass lens. Now, as good as a modern camera lens may be, it is still subject to lens errors that will cause distortions or 'artefacts' in the finished product. The floating flare is usually caused by astigmatism; a small astigmatism is often the result of asymmetric lens curvature due to mistakes in manufacture, or improper mounting of a lens in its frame, or changes to the orientation within the camera barrel (caused by a knock, or some other physical shock). In English, what this means is that the lens isn't a perfect curve. This slight aberration causes a distortion of the light entering the lens, so that certain wavelengths with be focused incorrectly. The imperfect diffraction of the light means that a 'hot spot' will be formed in the focal field of the lens. This distortion is aggravated by high levels of light (energy), such as a flash or full sunlight. These flash flares cause a 'hot spot' that overexposes the film, as the lens in the camera acts as any lens will, by concentrating energy into one area.. These distortions can only be avoided by the use of filters or a polarised lens, as these will reduce the 'energy' of the incoming light focused onto the sensitive film. This problem can occur in digital cameras, even in the absence of light-sensitive film, as the image will still react the same way to a flash flare. This is not the only way that an image can be altered by the lens. There might be geometric distortions, but they are usually too small to see unless you are using a fisheye lens to deliberately distort the picture. There can be chromatic imperfections caused by the refraction or dispersion of light by the lens - after all, a lens will tend to break up white light into a spectrum. I hope I've helped shed a little light on the subject… (Oof, I know, that is a truly dreadful pun.)
Science News Update Deep Impact In a previous Science Page, I mentioned the Deep Impact probe. This was an attempt, by NASA, to investigate the composition of a comet by crashing an object into Comet Tempel 1. Well, it was a success. (Notice that I've avoided the "smashing success" pun used by nearly every major media outlet. Ugh! One bad pun should be enough for today.) The experiment, which was particularly well-timed by occurring on the 4th of July – American Independence Day, saw a 372-kilogram copper projectile released by the Deep Impact craft and burrow into the comet. This created a release of a plume of debris, and created a crater. Scientists will now be busy analysing this debris, trying to collect data about the composition and structure of comets. It is thought that this information will give us insights into how the solar system was formed, as it theorised that comets are relatively unchanged matter from the original solar 'stuff'. A visit to the NASA website is very illuminating.
Biography Peter C. Doherty Peter Doherty shared the Nobel Prize in Physiology or Medicine 1996, with Rolf M. Zinkernagel, for "their discoveries concerning the specificity of the cell mediated immune defence." He was born in Oxley, Brisbane, in 1940. He achieved a Bachelor in Veterinary Science from the University of Queensland in 1962, and went on to complete a PhD in Edinburgh, Scotland, in 1970. He developed into a scientist interested in infectious disease and pathology, and became involved in a more medical-based research when he moved with his wife and children to Canberra in 1971. This is where he met with Zinkernagel, and they worked together on the killer T-cell of the immunology system, while both were employed at the John Curtin School of Medical Research. It was the work they did in 1973 that eventually lead to the Nobel Prize. Their key animal research showed that white blood cells (T-lymphocytes) must recognize both an invading virus and certain self molecules - the so-called major histocompatibility (MHC) antigens in order to kill the virus-infected cells. This concept of simultaneous recognition of both self and foreign molecules formed the basis for a new understanding of the specificity of the cellular immune system. This advanced the research in many clinical areas, including the understanding of how to treat certain types of cancer, and how to reduce the autoimmune response to certain inflammatory diseases, such as rheumatoid arthritis and multiple sclerosis. Peter Doherty is now the chairman of the Dept. of Immunology at St. Jude Children's Research Hospital in Memphis. An Australian to very, very proud of.
Concept of the Month
Now, in a very rough overview, the body uses three different types of autoimmune response to pathogens: T-cells (T-lymphocytes), B-lymphocytes and macrophages. There are four types of T-cells. T-lymphocytes are produced prior to contact with a foreign antigen. They recognise a specific antigen via molecular conformation, and then divide when activated by contact with the antigen to enhance the autoimmune response – becoming the Killer T-cells. After the infection, they differentiate memory cells for later use if and when the same antigen is encountered again (Memory T-cells). MHC 1 markers (major histocompatibility complexes) are the antigen presentation proteins recognised by Cytotoxic (Killer) T-cells. They help the T-cell recognise the enemy, so it can be destroyed. (Oh my, I hope this is completely correct. This is my best attempt at simplifying a very complex topic. IF anyone spots a problem, please let me know.)
Lynne's Literary Comment This is a new addition to the science page. I know that this is my Science Page, but I am also a writer (if you've read my bio, you know this already.) I'm not going to let the comment take over from the science…just complement it. |
| *The Voyager Science Queen is also known as Lynne Green So, who is this woman who attempts to entertain us with Science? Well, I really am a scientist. I have a Bachelor of Science degree from the University of Queensland, in Zoology. And, at the moment, I am working in a Pathology laboratory. I have always been intensely curious about every aspect of our universe, from the teeny tiny workings of the gene right up to the mind-bending forces that are twisting and knotting inside a blackhole. So, now I am sharing a brain stuffed full of trivia...and hopefully entertaining people at the same time. As well, I write Fantasy stories and novels. One day, I hope to have a book published, but don't hold your breath. Reading is my other major love, and my favourite authors are Terry Pratchett and Isaac Asimov, though I could list hundreds of others. If I had one wish, I ask for more time to write! Read previous Sci-Facts: Green by name, green by nature Looking for more scientific oddities? Have you checked out Dr Steven Juan's website? He is, quite literally, the wizard of odds! |
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