Archive for July 4, 2010

Mask Stereo Lithography And Selective Laser Sintering As Types Of RP.

Written by editor on . Posted in Computers and Technology

Mask stereo lithography. Faster version of this technology was developed by Cubital Inc. It is called “mask stereo lithography” (Solid Ground Curing or SGC). As the working material it is used the same photopolymer only it is lighted its entire surface with ultraviolet light through the artwork.

Photo mask for each layer is printed on the glass. For this it is used the technology, reminiscent of laser printing. Obviously, this method provides significant gains of performance at the expense of illumination at the same time of the polymer layer instead of the point wise scanning. For instance, the company Envisiontec Prefactory offers installation, which takes only 0.3 m 2, so it can be accommodated even in a small office. Material is lighted by the method of Digital Light Processing, or DLP, similar to that is used in digital projection systems. The size for a single working layer (cross section) is of 1280×1024 pixels with a physical pixel size of 150 or 90 microns. Thickness varies from 150 to 90 microns. Prefactory can create prototypes of up to 190x152x230 mm at speeds up to 15 mm (height) per hour. The control is performed with a computer operating system Linux, link with the outside – through a local network.

Selective laser sintering. An alternative method of stereo lithography is Selective Laser Sintering (or SLS). This process was developed in the 80′s of last century in the University of Texas at Austin and patented in 1989 by a graduate of the University Karl Dekard.

Selective laser sintering begins when a very thin layer of fusible during heating of the powder is placed into the cooking chamber of a cylindrical shape. It is used a laser for baking powder, resolved within the boundary of the contour of the working chamber. The laser increases the temperature of the powder to the melting point; there is a partial sintering material and forming it into a solid mass. The intensity of the beam is changed in such a way in order to smelt powder only in areas bounded by the geometry of the future construction. As soon as the laser processes the entire layer of powder in this section, immediately a new thin layer is poured and the process repeats. The component is removed from the processing zones and free powder is shaked. SLS-details can be obtained from powders with different grain sizes depending on the future use of parts.

Laser sintering provides a high quality of finished products, although the surface of the model is obtained porous. Advantage – is sufficient for small series production strength of parts. However, SLS-device is expensive, and the playback speed of a digital model is only a few centimeters per hour, plus a few hours on the heating and cooling of the device. In addition to good accuracy and high strength of derived objects, SLS has also such a dignity as an opportunity to receive details of moving parts, such as moving loop connections.

Do you face the problem when you want to show your product but there is no model? Then definitely you require rapid prototyping. In addition this technology may be of great use for marketing while the product has not been produced yet. Interesting? Go to this cheap rapid prototyping site.

This rapid prototyping methodology is a strong tool nowadays. Use it to study products, their weak and strong points. Also keep in mind that modern Internet technologies offer you a unique chance to try and to find anything you might require. Should you want to keep track of the latest publications on the subject.

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Predators Movie Facts

Written by editor on . Posted in Movies and Celebrities

The official plot synopsis of Predators has been revealed:

Plot of Predators:
“A bold new chapter in the Predator universe, Predators was shot on location under Rodriguez’s creative auspices at the filmmaker’s Austin-based Troublemaker Studios, and is directed by Nimrod Antal. The film stars Adrien Brody as Royce, a mercenary who reluctantly leads a group of elite warriors who come to realize they’ve been brought together on an alien planet… as prey.
With the exception of a disgraced physician, they are all cold-blooded killers – mercenaries, Yakuza, convicts, death squad members – human “predators” that are now being systemically hunted and eliminated by a new breed of alien Predators. In addition to Adrien Brody, the film stars Topher Grace, Alice Braga, and Laurence Fishburne. Co-starring are Walton Goggins, Danny Trejo, Oleg Taktarov and Mahershalalhashbaz Ali.”
So it’s a kind of reboot. Robert Rodriguez is damn confident that he can bring the Predator franchise to its heyday:

Here’s a break down of the movie cast of Predators:

- Royce (Adrien Brody): main character, a Steve McQueen-type

- Cuchillo (Danny Trejo): a Mexican enforcer from a drug cartel who has twin uzi strapped to his back

The release date of Predators is tentatively set for July 7, 2010. But they haven’t started to film yet…

Read More on Predators Movie Blog

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Best Science Books for 2009

Written by admin on . Posted in Book Reviews, Science and Technology

Best Science Books for 2009

Welcome to our Best of 2009 top 10 lists for Science. Our list of the best science books of 2009  includes top pick, The Age of Wonder, Richard Holmes’s delightfully masterful group biography of the adventurous scientists of Britain’s Romantic age, Remarkable Creatures: Epic Adventures in the Search for the Origin of Species, Complexity: A Guided Tour and other top science books.

Best Science Books are ranked according to Amazon’s customer orders through October. Only books published for the first time in 2009 are eligible. See more editors’ picks and customers’ favorites in our Best Books of 2009 Store.


1. The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science

Amazon.com Review

Oliver Sacks is the author of Musicophilia, Awakenings, The Man Who Mistook His Wife for a Hat, and many other books, for which he has received numerous awards, including the Hawthornden Prize, a Polk Award, and a Guggenheim Fellowship. He is a member of the American Academy of Arts and Letters and lives in New York City, where he is a practicing neurologist. Read his exclusive guest review of The Age of Wonder:

I am a Richard Holmes addict. He is an incomparable biographer, but in The Age of Wonder, he rises to new heights and becomes the biographer not of a single figure, but of an entire unique period, when artist and scientist could share common aims and ambitions and a common language–and together create a “romantic,” humanist science. We are once again on the brink of such an age, when science and art will come together in new and powerful ways. For this we could have no better model than the lives of William and Caroline Herschel and Humphry Davy, whose dedication and scientific inventiveness were combined with a deep sense of wonder and poetry in the universe. Only Holmes, who is so deeply versed in the people and culture of eighteenth-century science, could tell their story with such verve and resonance for our own time.


2. Remarkable Creatures: Epic Adventures in the Search for the Origin of Species

It’s unclear whether the title refers to the daring naturalist/explorers Carroll depicts or the creatures whose remains they found. In this thoroughly enjoyable book, Carroll (Endless Forms Most Beautiful), a molecular biologist at the University of Wisconsin, provides vignettes of some of the fascinating people who have made the most significant discoveries in evolutionary biology. He starts with some of the experiences and insights of great explorers like Alexander von Humboldt, Charles Darwin, Alfred Russel Wallace and Henry Walter Bates, then turns his attention to paleontologists who searched for the fossil evidence to support the new theory of evolution. Among them are Euge`ne Dubois’s discovery of Java Man; Charles Walcott’s discovery of the Burgess Shale and the evidence it provided for the Cambrian explosion; and Neil Shubin’s recent discovery in arctic Canada of Tiktaalik, the intermediary between water- and land-dwelling vertebrates. Carroll closes with studies of human evolution, from Louis and Mary Leakey to the advances of Linus Pauling and Allan Wilson, which indicated that Neanderthals were cousins of Homo sapiens rather than direct ancestors. While there’s little that’s new here, Carroll does weave an arresting tapestry of evolutionary advancement.


3. Complexity: A Guided Tour

“All theoretical models are wrong, but some are useful.” Both inevitable error and promising usefulness abound in the bold conceptual models that Mitchell surveys in exploring the nascent science of complexity. Readers will marvel at the sheer range of settings in which complex systems operate: from ant hills to the stock market, from T cells to Web searches, from disease epidemics to power outages, complexity challenges theorists’ intellectual adroitness. With refreshing clarity, Mitchell invites nonspecialists to share in these researchers’ adventures in recognizing and measuring complexity and then predicting its cascading effects. Concepts central to thermodynamics, information theory, and computer programming all come into focus in this foray into the recesses of complexity. Still, the analysis illuminates more than explanatory frameworks (such as network diagrams and genetic algorithms); piquant personalities (including Stephen Jay Gould and John von Neumann) also receive illuminating scrutiny. Though Mitchell acknowledges the doubts of skeptics, she still expresses hope that persistent complexity researchers will yet weld their disparate accomplishments into a coherent paradigm. Mind-expanding.


4. Fixing My Gaze: A Scientist’s Journey Into Seeing in Three Dimensions

“Fixing My Gaze is a beautiful description and appreciation of two very distinct ways of seeing… But it is also an exploration of much more. Sue is at pains not only to present her story, in clear and lucid, often poetic, language, but also, as a scientist, to provide understanding and explanation. She is in a unique position to do this, drawing on both her personal experience and her background as a neurobiologist….

Though Sue originally thought her own case unique, she has since found a number of other people with strabismus and related problems who have unexpectedly achieved stereo vision through vision therapy. This is no easy accomplishment. It may require not only optical corrections (proper lenses or prisms, for example), but very intensive training and learning—in effect, learning how to align the eyes and to fuse their images, and unlearning the unconscious habit of suppressing vision which has been occurring perhaps for decades. In this way, vision therapy is directed at the whole person: it requires high motivation and self-awareness, and enormous perseverance, practice and determination, as does psychotherapy, for instance, or learning to play the piano. But it is also highly rewarding, as Sue brings out. And this ability to acquire new perceptual abilities later in life has great implications for anyone interested in neuroscience or rehabilitation, and, of course, for the millions of people who, like Sue, have been strabismic since infancy.

Sue’s case, and many others, suggest that if there are even small islands of function in the visual cortex, there may be a fair chance of reactivating and expanding them in later life, even after a lapse of decades, if vision can be made optically possible. Cases like these may offer new hope for those once considered incorrigibly stereo-blind. Fixing My Gaze will offer inspiration for anyone in this situation, but it is equally a very remarkable exploration of the brain’s ability to change and adapt, and an ode to the fascination and wonder of the visual world, even those parts of it which many of us take for granted.”


5.The Strangest Man: The Hidden Life of Paul Dirac, Mystic of the Atom

Paul Dirac (1902–1984) shared the Nobel Prize for physics with Erwin Schrödinger in 1933, but whereas physicists regard Dirac as one of the giants of the 20th century, he isn’t as well known outside the profession. This may be due to the lack of humorous quips attributed to Dirac, as compared with an Einstein or a Feynman. If he spoke at all, it was with one-word answers that made Calvin Coolidge look loquacious . Dirac adhered to Keats’s admonition that Beauty is truth, truth beauty: if an equation was beautiful, it was probably correct, and vice versa. His most famous equation predicted the positron (now used in PET scans), which is the antiparticle of the electron, and antimatter in general. In 1955, Dirac came up with a primitive version of string theory, which today is the rock star branch of physics. Physicist Farmelo (It Must Be Beautiful) speculates that Dirac suffered from undiagnosed autism because his character quirks resembled autism’s symptoms. Farmelo proves himself a wizard at explaining the arcane aspects of particle physics. His great affection for his odd but brilliant subject shows on every page, giving Dirac the biography any great scientist deserves.


6. Every Patient Tells a Story

In her first book, internist and New York Times columnist Sanders discusses how doctors deal with diagnostic dilemmas. Unlike Berton Roueché in his books of medical puzzles, Sanders not only collects difficult cases, she reflects on what each means for both patient and struggling physician. A man arrives at the hospital, delirious, his kidneys failing. Batteries of tests are unrevealing, but he quickly recovers after a resident extracts two quarts of urine. An abdominal exam would have detected the patient’s obstructed, grossly swollen bladder. The author then ponders the neglect of the physical exam, by today’s physicians, enamored with high-tech tests that sometimes reveal less than a simple exam. Another patient, frustrated at her doctor’s failure to diagnose her fever and rash, googles her symptoms and finds the correct answer. Sanders uses this case to explain how computers can help in diagnoses (Google is not bad, she says, but better programs exist). Readers who enjoy dramatic stories of doctors fighting disease will get their fill, and they will also encounter thoughtful essays on how doctors think and go about their work, and how they might do it better.


7. The Mathematical Mechanic: Using Physical Reasoning to Solve Problems

Mark Levi’s book “The Mathematical Mechanic” is a wonderful attempt to integrate physical reasoning with mathematical reasoning. These two strands have historically run in parallel and only occasionally have they been united at least at a pedagogical level. There seems to be a trend among Russian mathematicians particularly in the area of differential equations whereby they use physical reasoning to illuminate the more abstract mathematical approaches that are taken. V I Arnold is an example someone who has been known to integrate the two approaches. Perhaps Levi’s Russian roots explain some of the impetus for this book. As mathematics becomes more and more specialized I fear that fewer mathematicians have the time or even inclination to think about the interconnections between physical reasoning and their own area. Levi’s book is an antidote to that trend and he is to be congratulated for his efforts.

What Levy does is to take a large number of mathematical problems/theorems and show how physical reasoning using concepts such as conservation of energy, torque, resolution of forces, etc can be used to solve what are quite fundamental problems/theorems. In Chapter 2 he uses essentially torque concepts to prove the Pythagorean theorem be a thought experiment involving a right angled prism sitting in a water filled fish tank but attached to a spindle so it can rotate. The fact that it doesn’t (ie there is zero net torque) leads directly to Pythagoras’ Theorem.


8. Truth, Lies, and O-Rings: Inside the Space Shuttle Challenger Disaster

On a cold January morning in 1986, NASA launched the Space Shuttle Challenger, despite warnings against doing so by many individuals, including Allan McDonald. The fiery destruction of Challenger on live television moments after launch remains an indelible image in the nation’s collective memory. In “Truth, Lies, and O-Rings”, McDonald, a skilled engineer and executive, relives the tragedy from where he stood at Launch Control Center. As he fought to draw attention to the real reasons behind the disaster, he was the only one targeted for retribution by both NASA and his employer, Morton Thiokol, Inc., makers of the shuttle’s solid rocket boosters. In this whistle-blowing yet rigorous and fair-minded book, McDonald, with the assistance of internationally distinguished aerospace historian James R. Hansen, addresses all of the factors that led to the accident, some of which were never included in NASA’s “Failure Team” report submitted to the Presidential Commission. “Truth, Lies, and O-Rings” is the first look at the Challenger tragedy and its aftermath from someone who was on the inside, recognized the potential disaster, and tried to prevent it. It also addresses the early warnings of very severe debris issues from the first two post-Challenger flights, which ultimately resulted in the loss of Columbia some fifteen years later. What they didn’t want you to know.


9. Dissection: Photographs of a Rite of Passage in American Medicine 1880-1930

This is a startling window into the education of American doctors in the late 19th and early 20th centuries-on both a visceral level and for its revealing cultural record. Cringe-worthy shots of medical students-bare-handed gentlemen and a few ladies in street clothes show off their scalpels, saws and textbooks-while their cadavers, mostly poor and black, are awkwardly posed, and exposed. In one stunning shot, a black woman looks out from behind the young students. “What are we to make of an African-American woman, standing, broom handle in hand, behind the dissection table, her gaze fixed on the camera?” the authors ask. More importantly, they conclude, the photo is now drawn “out of the shadows of history” where “we can at least bear witness.” A blood-soaked dissection table makes you want to look away and the dark humor of students playing pranks with skeletons are both hilarious and horrible. Postcards sent to family and friends must have caused shock and awe for postmen and recipient alike. Here, a difficult glance into medicine’s “uncomfortable past” offers a grand opportunity to understand the legacy doctors and patients live with, and benefit from, today.


10. The Monty Hall Problem: The Remarkable Story of Math’s Most Contentious Brain Teaser

Mathematicians call it the Monty Hall Problem, and it is one of the most interesting mathematical brain teasers of recent times. Imagine that you face three doors, behind one of which is a prize. You choose one but do not open it. The host–call him Monty Hall–opens a different door, always choosing one he knows to be empty. Left with two doors, will you do better by sticking with your first choice, or by switching to the other remaining door? In this light-hearted yet ultimately serious book, Jason Rosenhouse explores the history of this fascinating puzzle. Using a minimum of mathematics (and none at all for much of the book), he shows how the problem has fascinated philosophers, psychologists, and many others, and examines the many variations that have appeared over the years. As Rosenhouse demonstrates, the Monty Hall Problem illuminates fundamental mathematical issues and has abiding philosophical implications. Perhaps most important, he writes, the problem opens a window on our cognitive difficulties in reasoning about uncertainty.

You can also check the list of Best Science Books in 2010.






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Open Source Document Management System. Useful Facts To Know

Written by editor on . Posted in Computers and Technology

If you were looking for some information about open source document management system then it means you found what you needed. So, what exactly the open source document management system is? To start with, you should be aware of that it signifies the once unattainable limit among document management, for instance, paper documents that involve a lot of time and space for management. Additionally, it should be pointed out that this document management system facilitates the circulation of info into vast groups of individuals from numerous departments and locations.

Due to the fact that information management always involves mammoth costs and taking into account the deficiency in client control, the open document management system has been created in order to deal with these serious problems. The truth is that this document management system allocates the clients to use files as a collective record. It is besides essential to add here that it allows no desktop installations and it will be possible to accumulate, distribute or store files in a really uncomplicated manner.

It is also useful for you to remember that the open source document management system work in partnership with Open office and Microsoft office. As a result it means that it will be possible to formulate the data and information flow. It should be also pointed out that in this way a standard shared drive can be turnes into a fundamental system of files where you can assemble the contents of the applications you require. Needless to say that you will be also provided with such a vital option as informing other users of definite records or information in the course of email connections.

While talking more about this issue it is impossible to neglect the fact that by the use of this management system it is possible to attach and recover the later utilizing a set of keyword linked to the file you saved and need to recover. As a matter of fact the keywords that should be used for this are extracted by the program by means of the creator of the documents.

Finally it should be stated that an open source document management system will besides provide you with a lot of other functional options you will make use of for efficient work, for example, it also features web content management, image management, document management, records management, content platform depository and content management interoperability service.

There is no need to mention that nowadays every company should use document management system in order to make the whole working process really efficient. So, if you consider choosing a document management system or need more information about document management system – visit this site.

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