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Wednesday, August 12, 2009

Hundreds Of New Species Discovered In Eastern Himalayas


Over 350 new species including the world’s smallest deer, a “flying frog” and a 100 million-year old gecko have been discovered in the Eastern Himalayas, a biological treasure trove now threatened by climate change.

Flying frog (Rhacophorus suffry). The bright green, red-footed tree frog was described in 2007. It is a 'flying frog' because long webbed feet allow the species to glide when falling. (Credit: Copyright Totul Bortamuli / WWF Nepal)

A decade of research carried out by scientists in remote mountain areas endangered by rising global temperatures brought exciting discoveries such as a bright green frog that uses its red and long webbed feet to glide in the air.


One of the most significant findings was not exactly “new” in the classic sense. A 100-million year-old gecko, the oldest fossil gecko species known to science, was discovered in an amber mine in the Hukawng Valley in the northern Myanmar.


The WWF report The Eastern Himalayas – Where Worlds Collide details discoveries made by scientists from various organizations between 1998 and 2008 in a region reaching across Bhutan and north-east India to the far north of Myanmar as well as Nepal and southern parts of Tibet Autonomus Region (China).


“The good news of this explosion in species discoveries is tempered by the increasing threats to the Himalayas’ cultural and biological diversity,” said Jon Miceler, Director of WWF’s Eastern Himalayas Program. “This rugged and remarkable landscape is already seeing direct, measurable impacts from climate change and risks being lost forever.”


In December world leaders will gather in Copenhagen to reach an agreement on a new climate deal, which will replace the existing Kyoto Protocol.


The Eastern Himalayas- Where Worlds Collide describes more than 350 new species discovered - including 244 plants, 16 amphibians, 16 reptiles, 14 fish, 2 birds, 2 mammals and at least 60 new invertebrates.


The report mentions the miniature muntjac, also called the “leaf deer,” which is the world’s oldest and smallest deer species. Scientists initially believed the small creature found in the world’s largest mountain range was a juvenile of another species but DNA tests confirmed the light brown animal with innocent dark eyes was a distinct and new species.


The Eastern Himalayas harbor a staggering 10,000 plant species, 300 mammal species, 977 bird species, 176 reptiles, 105 amphibians and 269 types of freshwater fish. The region also has the highest density of Bengal tigers in the world and is the last bastion of the charismatic greater one-horned rhino.


WWF is working to conserve the habitat of endangered species such as snow leopards, Bengal tigers, Asian elephants, red pandas, takin, golden langurs, Gangetic dolphins and one-horned rhinos.


Historically, the rugged and largely inaccessible landscape of the Eastern Himalayas has made biological surveys in the region extremely difficult. As a result, wildlife has remained poorly surveyed and there are large areas that are still biologically unexplored.


Today further species continue to be unearthed and many more species of amphibians, reptiles and fish are currently in the process of being officially named by scientists.



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Saturday, August 8, 2009

Scientists Find Universal Rules For Food-web Stability


New findings, published in the journal Science, conclude that food-web stability is enhanced when many diverse predator-prey links connect high and intermediate trophic levels. The computations also reveal that small ecosystems follow other rules than large ecosystems: differences in the strength of predator-prey links increase the stability of small webs, but destabilize larger webs.


A Juvenile African Bush Viper (Atheris chlorechis) with a small frog, at night.
Researchers found that food-web stability is enhanced when many diverse predator-prey links connect high and intermediate trophic levels. (Credit: iStockphoto/Mark Kostich)


Natural ecosystems consist of interwoven food chains, in which individual animal or plant species function as predator or prey. Potential food webs not only differ by their species composition, but also vary in their stability. Observable food webs are stable food webs, with the relationships between their species remaining constant over relatively long periods of time.


Understanding complex systems such as food webs present major challenges to science. They can either be examined by observing natural environments, or by computer simulations. To enable computer simulations of such systems, scientists often have to make simplifying assumptions, keeping the number of model parameters as low as possible. Yet, the computational demands of such simulations are high and their relevance is often limited.


Innovative methodology


Scientists from the Max Planck Institute for the Physics of Complex Systems (MPIPKS) in Dresden, Germany, have developed a new method that allows them to efficiently analyze the impact of innumerable parameters on complex systems.


"By using a method called generalized modeling, we examine whether a given food web can, in principle, be stable, i.e., whether its species can coexist in the long term," says Thilo Gross from MPIPKS. Complex ecosystems can thus be simulated and analyzed under almost any conditions. "In this way we can estimate which parameters will keep ecosystems stable and which will upset their balance."


The method can also be used for examining other complex systems, such as human metabolism or gene regulation.


Generalists stabilize, specialists destabilize


Applying this innovative modeling approach together with colleagues at the International Institute for Applied Systems Analysis (IIASA) in Laxenburg, Austria, and Princeton University, USA, the scientists have succeeded in discovering not just one, but several universal rules in the dynamics of ecosystems.


"Food-web stability is enhanced when species at high trophic levels feed on multiple prey species and species at intermediate trophic levels are fed upon by multiple predator species," says Ulf Dieckmann of IIASA.


The scientists have also identified additional stabilizing and destabilizing factors within ecosystems. Ecosystems with high densities of predator-prey links are less likely to be stable, while a strong dependence of predation on predator density destabilizes the system. On the other hand, a strong dependence of predation on prey density has a stabilizing impact on food webs.


Differences between small and large systems


A further important finding is that food webs consisting of only a few species behave qualitatively different from webs consisting of many species.


"Small ecosystems apparently follow different rules than large ecosystems," says Ulf Dieckmann. "Systems with fewer species are more stable if there are strong interactions between some species, but only weak interactions between others. For food webs with many species, exactly the opposite is true. Extremely strong or weak predator-prey links in nature should therefore be the rarer the more species a food web contains," he concludes.



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Friday, August 7, 2009

Nanoscale Origami From DNA


Scientists at the Technische Universitaet Muenchen (TUM) and Harvard University have thrown the lid off a new toolbox for building nanoscale structures out of DNA, with complex twisting and curving shapes. In the August 7 issue of the journal Science, they report a series of experiments in which they folded DNA, origami-like, into three dimensional objects including a beachball-shaped wireframe capsule just 50 nanometers in diameter.


Scientists at the Technische Universitaet Muenchen and Harvard University have thrown the lid off a new toolbox for building nanoscale structures out of DNA, with complex twisting and curving shapes. They report a series of experiments in which they folded DNA, origami-like, into 3-D objects including a beach ball-shaped wireframe capsule just 50 nanometers in diameter. (Credit: Used by permission of H. Dietz, TUM Dept. of Physics, all rights reserved.)

"Our goal was to find out whether we could program DNA to assemble into shapes that exhibit custom curvature or twist, with features just a few nanometers wide," says biophysicist Hendrik Dietz, a professor at the Technische Universitaet Muenchen. Dietz's collaborators in these experiments were Professor William Shih and Dr. Shawn Douglas of Harvard University. "It worked," he says, "and we can now build a diversity of three-dimensional nanoscale machine parts, such as round gears or curved tubes or capsules. Assembling those parts into bigger, more complex and functional devices should be possible."


As a medium for nanoscale engineering, DNA has the dual advantages of being a smart material – not only tough and flexible but also programmable – and being very well characterized by decades of study. Basic tools that Dietz, Douglas, and Shih employ are programmable self-assembly – directing DNA strands to form custom-shaped bundles of cross-linked double helices – and targeted insertions or deletions of base pairs that can give such bundles a desired twist or curve. Right-handed or left-handed twisting can be specified. They report achieving precise, quantitative control of these shapes, with a radius of curvature as tight as 6 nanometers.


The toolbox they have developed includes a graphical software program that helps to translate specific design concepts into the DNA programming required to realize them. Three-dimensional shapes are produced by "tuning" the number, arrangement, and lengths of helices.


In their current paper, the researchers present a wide variety of nanoscale structures and describe in detail how they designed, formed, and verified them. "Many advanced macroscopic machines require curiously shaped parts in order to function," Dietz says, "and we have the tools to make them. But we currently cannot build something intricate such as an ant's leg or, much smaller, a ten-nanometer-small chemical plant such as a protein enzyme. We expect many benefits if only we could build super-miniaturized devices on the nanoscale using materials that work robustly in the cells of our bodies – biomolecules such as DNA."



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Monday, August 3, 2009

Why We Learn More From Our Successes Than Our Failures


If you've ever felt doomed to repeat your mistakes, researchers at MIT's Picower Institute for Learning and Memory may have explained why: Brain cells may only learn from experience when we do something right and not when we fail.

Given different images as cues, monkeys were trained to look right or left for rewards.
MIT neuroscientists found that neurons responded differently following correct and
incorrect responses, with correct responses setting up the brain for additional successes.
(Credit: Courtesy / Earl Miller)


In the July 30 issue of the journal Neuron, Earl K. Miller, the Picower Professor of Neuroscience, and MIT colleagues Mark Histed and Anitha Pasupathy have created for the first time a unique snapshot of the learning process that shows how single cells change their responses in real time as a result of information about what is the right action and what is the wrong one.


"We have shown that brain cells keep track of whether recent behaviors were successful or not," Miller said. Furthermore, when a behavior was successful, cells became more finely tuned to what the animal was learning. After a failure, there was little or no change in the brain — nor was there any improvement in behavior.


The study sheds light on the neural mechanisms linking environmental feedback to neural plasticity — the brain's ability to change in response to experience. It has implications for understanding how we learn, and understanding and treating learning disorders.


Rewarding success


Monkeys were given the task of looking at two alternating images on a computer screen. For one picture, the animal was rewarded when it shifted its gaze to the right; for another picture it was supposed to look left. The monkeys used trial and error to figure out which images cued which movements.


The researchers found that whether the animals' answers were right or wrong, signals within certain parts of their brains "resonated" with the repercussions of their answers for several seconds. The neural activity following a correct answer and a reward helped the monkeys do better on the trial that popped up a few seconds later.


"If the monkey just got a correct answer, a signal lingered in its brain that said, 'You did the right thing.' Right after a correct answer, neurons processed information more sharply and effectively, and the monkey was more likely to get the next answer correct as well," Miller said, "But after an error there was no improvement. In other words, only after successes, not failures, did brain processing and the monkeys' behavior improve."


Split-second influence


The prefrontal cortex orchestrates thoughts and actions in accordance with internal goals while the basal ganglia are associated with motor control, cognition and emotions. This work shows that these two brain areas, long suspected to play key roles in learning and memory, have full information available to them to do all the neural computations necessary for learning.


The prefrontal cortex and basal ganglia, extensively connected with each other and with the rest of the brain, are thought to help us learn abstract associations by generating brief neural signals when a response is correct or incorrect. But researchers never understood how this transient activity, which fades in less than a second, influenced actions that occurred later.


In this study, the researchers found activity in many neurons within both brain regions that reflected the delivery or withholding of a reward lasted for several seconds, until the next trial. Single neurons in both areas conveyed strong, sustained outcome information for four to six seconds, spanning the entire time frame between trials.


Response selectivity was stronger on a given trial if the previous trial had been rewarded and weaker if the previous trial was an error. This occurred whether the animal was just learning the association or was already good at it.


After a correct response, the electrical impulses coming from neurons in each of the brain areas was more robust and conveyed more information. "The signal-to-noise ratio improved in both brain regions," Miller said. "The heightened response led to them being more likely to get the next trial correct, too. This explains on a neural level why we seem to learn more from our successes than our failures."


In addition to Miller, authors include former MIT graduate student Mark H. Histed, now a postdoctoral fellow at Harvard Medical School, and former postdoctoral fellow Anitha Pasupathy, now an assistant professor at the University of Washington.


This work is supported by National Institute of Neurological Disorders and Stroke and the Tourette's Syndrome Association.


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Friday, July 24, 2009

Nanotubes Weigh A Single Atom


How can you weigh a single atom? European researchers have built an exquisite new device that can do just that. It may ultimately allow scientists to study the progress of chemical reactions, molecule by molecule.

A diagram (above) and real-life image (inset) of a carbon nanotube.
(Credit: CARDEQ Project (www.cardeq.eu)


Carbon nanotubes are ultra-thin fibres of carbon and a nanotechnologist’s dream.


They are made from thin sheets of carbon only one atom thick – known as graphene – rolled into a tube only a few nanometres across. Even the thickest is more than a thousand times thinner than a human hair.


Interest in carbon nanotubes blossomed in the 1990s when they were found to possess impressive characteristics that make them very attractive raw materials for nanotechnology of all kinds.


“They have unique properties,” explains Professor Pertti Hakonen of Helsinki University of Technology. “They are about 1000 times stronger than steel and very good thermal conductors and good electrical conductors.”


Hakonen is coordinator of the EU-funded CARDEQ project (http://www.cardeq.eu/) which is exploiting these intriguing materials to build a device sensitive enough to measure the masses of atoms and molecules.


Vibrating strings


A carbon nanotube is essentially an extremely thin, but stiff, piece of string and, like other strings, it can vibrate. As all guitar players know, heavy strings vibrate more slowly than lighter strings, so if a suspended carbon nanotube is allowed to vibrate at its natural frequency, that frequency will fall if atoms or molecules become attached to it.


It sounds simple and the idea is not new. What is new is the delicate sensing system needed to detect the vibration and measure its frequency. Some nanotubes turn out to be semiconductors, depending on how the graphene sheet is wound, and it is these that offer the solution that CARDEQ has developed.


Members of the consortium have taken the approach of building a semiconducting nanotube into a transistor so that the vibration modulates the current passing through it. “The suspended nanotube is, at the same time, the vibrating element and the readout element of the transistor,” Hakonen explains.


“The idea was to run three different detector plans in parallel and then select the best one,” he says. “Now we are down to two. So we have the single electron transfer concept, which is more sensitive, and the field effect transistor concept, which is faster.”


Single atoms


Last November, CARDEQ partners in Barcelona reported that they had sensed the mass of single chromium atoms deposited on a nanotube. But Hakonen says that even smaller atoms, of argon, can now be detected, though the device is not yet stable enough for such sensitivity to be routine. “When the device is operating well, we can see a single argon atom on short time scales. But then if you measure too long the noise becomes large.”


CARDEQ is not alone in employing carbon nanotubes as mass sensors. Similar work is going on at two centres in California – Berkeley and Caltech – though each has adopted a different method to measuring the mass.


All three groups have announced they can perform mass detection on the atomic level using nanotubes, but CARDEQ researchers provided the most convincing data with a clear shift in the resonance frequency.


But a single atom is nowhere near the limit of what is possible. Hakonen is confident they can push the technology to detect the mass of a single nucleon – a proton or neutron.


“It’s a big difference,” he admits, “but typically the improvements in these devices are jump-like. It’s not like developing some well-known device where we have only small improvements from time to time. This is really front-line work and breakthroughs do occur occasionally.”


Biological molecules


If the resolution can be pared down to a single nucleon, then researchers can look forward to accurately weighing different types of molecules and atoms in real time.


It may then become possible to observe the radioactive decay of a single nucleus and to study other types of quantum mechanical phenomena.


But the real excitement would be in tracking chemical and biological reactions involving individual atoms and molecules reacting right there on the vibrating nanotube. That could have applications in molecular biology, allowing scientists to study the basic processes of life in unprecedented detail. Such practical applications are probably ten years away, Hakonen estimates.


“It will depend very much on how the technology for processing carbon nanotubes develops. I cannot predict what will happen, but I think chemical reactions in various systems, such as proteins and so on, will be the main applications in the future.”


The CARDEQ project received funding from the FET-Open strand of the EU’s Sixth Framework Programme for ICT research.



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Friday, July 17, 2009

Capturing Carbon Dioxide In Tiny Bowls: Global Warming Fix From Microbes?


The accidental discovery of a bowl-shaped molecule that pulls carbon dioxide out of the air suggests exciting new possibilities for dealing with global warming, including genetically engineering microbes to manufacture those CO2 "catchers," a scientist from Maryland reports.

An unusual bowl-shaped molecule (shown) that pulls carbon dioxide out of the air may provide exciting new possibilities for dealing with global warming, a scientist says. (Credit: The American Chemical Society)

J. A. Tossell notes in the new study that another scientist discovered the molecule while doing research unrelated to global climate change. Carbon dioxide was collecting in the molecule, and the scientist realized that it was coming from air in the lab. Tossell recognized that these qualities might make it useful as an industrial absorbent for removing carbon dioxide.


Tossell's new computer modeling studies found that the molecule might be well-suited for removing carbon dioxide directly from ambient air, in addition to its previously described potential use as an absorbent for CO2 from electric power plant and other smokestacks. "It is also conceivable that living organisms may be developed which are capable of emplacing structurally ion receptors within their cell membranes," the report notes.


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Thursday, July 9, 2009

Spontaneous Assembly: A New Look At How Proteins Assemble And Organize Themselves Into Complex Patterns


Self-assembling and self-organizing systems are the Holy Grails of nanotechnology, but nature has been producing such systems for millions of years. A team of scientists has taken a unique look at how thousands of bacterial membrane proteins are able to assemble into clusters that direct cell movement to select chemicals in their environment. Their results provide valuable insight into how complex periodic patterns in biological systems can be generated and repaired.

PALM is an an ultrahigh-precision visible light microscopy
technique that enables scientists to photo-actively fluoresce
and image individual proteins. This PALM composite of an
E.coli bacterial cell shows the organization of proteins in
the chemotaxis signaling network.
(Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory)


Researchers with Berkeley Lab, the University of California (UC) Berkeley, the Howard Hughes Medical Institute, and Princeton University, used an ultrahigh-precision visible light microscopy technique called PALM - for Photo-Activated Localization Microscopy - to show that the chemotaxis network of signaling proteins in E.coli bacteria is able to spontaneously form from clusters of proteins without being actively distributed or attached to specific locations in cells. This simple organizational mechanism - dubbed “stochastic self-assembly” - is related to the self-organizing patterns first described in 1952 by the British computer scientist Alan Turing.


“It is not widely appreciated that complex periodic patterns can spontaneously emerge from simple mechanisms, but that is probably what is happening here,” said Jan Liphardt, the biophysicist who led this research.


Liphardt holds a joint appointment with Berkeley Lab’s Physical Biosciences Division and UC Berkeley’s Physics Department. He is the principal author of a paper now available PLoS Biology. Co-authoring the paper with Liphardt were Derek Greenfield, Ann McEvoy, Hari Shroff, Gavin Crooks, Ned Wingreen and Eric Betzig.


Key to a cell’s survival is the manner in which its critical components - proteins, lipids, nucleic acids, etc. - are arranged. For cells to thrive, the organization of these components must be optimized for their respective activities and also reproducible for succeeding generations of cells. Eukaryotic cells feature distinct subcellular structures, such as membrane-bound organelles and protein transport systems, whose complex organization is readily apparent. However, there is also complex spatial organization to be found within prokaryotic cells, such as rod-shaped bacteria like E. coli.


“It has remained somewhat mysterious how bacteria are able to organize and spatially segregate their interiors and membranes,” said Liphardt. “Two cells which are biochemically identical can have very different behaviors, depending upon their spatial organization. With new technologies such as PALM, we are able to see exactly how cells are organized and relate spatial organization with biological function.”


PALM and the Chemotaxis Network


In the PALM technique, target proteins are labeled with tags that fluoresce when activated by weak ultraviolet light. By keeping the intensity of this light sufficiently low, researchers can photoactivate individual proteins.


“Since individual proteins are imaged one at a time, we can localize and count them, and then computationally assemble the locations of all proteins into a composite, high-precision image,” said Liphardt. “With other technologies, we have to choose between observing large clusters or observing single proteins. With PALM, we can examine a cell and see single proteins, protein dimers, and so forth, all the way up to large clusters containing thousands of proteins. This enables us to see the relative organization of individual proteins within clusters and at the same time see how clusters are arranged with respect to one-another.”


Liphardt and his colleagues applied the PALM technique to the E.coli chemotaxis network of signaling proteins, which direct the movement of the bacteria towards or away from sugars, amino acids, and many other soluble molecules in response to environmental cues. The E.coli chemotaxis network is one of the best-understood of all biological signaling systems and is a model for studying bacterial spatial organization because its components display a nonrandom, periodic distribution in the cell membrane.


“Chemotaxis proteins cluster into large sensory complexes that localize to the poles of the bacterial cell,” Liphardt said. “We wanted to understand how these clusters form, what controls their size and density, and how the cellular location of clusters is robustly maintained in growing and dividing cells.”


Using PALM, Liphardt and his colleagues mapped the cellular locations of three proteins central to the chemotaxis signaling network - Tar, CheY and CheW - with a mean precision of 15 nanometers. They found that cluster sizes were distributed with no one size being “characteristic.” For example, a third of the Tar proteins were part of smaller lateral clusters and not of the large polar clusters. Analysis of the relative cellular locations of more than one million individual proteins from 326 cells determined that they are not actively distributed or attached to specific locations in cells, as had been hypothesized.


“Instead,” said Liphardt, “random lateral protein diffusion and protein-protein interactions are probably sufficient to generate the observed complex, ordered patterns. This simple stochastic self-assembly mechanism, which can create and maintain periodic structures in biological membranes without direct cytoskeletal involvement or active transport, may prove to be widespread in both prokaryotic and eukaryotic cells.”


Liphardt and his research group are now applying PALM to signaling complexes in eukaryotic membranes to see how widespread is stochastic self-assembly in nature. Given that biological systems are nature’s version of nanotechnology, the demonstration that stochastic self-assembly is capable of organizing thousands of proteins into complex and reproducible patterns holds promise for a wide range of applications in nanotechnology, including the fabrication of nanodevices and the development of nanoelectronic circuits.


This work was funded by the U.S. Department of Energy’s Office of Science, Energy Biosciences Program, the Sloan and Searle Foundations, and National Institutes of Health grants.


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Tuesday, July 7, 2009

MP3 Quality Modifier


Great sound quality at small file sizes – perfect for your phone!


A lot of mobile phones are getting to be quite capable of playing back audio as well as standalone portable music players. Sony’s Walkman series and Nokia’s XPressMusic series of phones have sold like hot cakes recently.

The problem for a music lover, though, is fitting his entire collection into the small amount of disk space available. A lot of these phones do not support memory cards of more than 4-8GB, with some incapable of reading a card over 2GB. Alternately, a few handsets tend to get quite slow when a lot of data is stored on them.

Of course, managing a lot of music is also difficult on the smaller MP3 players, such as the iPod Shuffle, the Creative Zen Stone, etc. So space management has become an issue for music aficionados.

A great tool to try out is the MP3 Quality Modifier, which promises to take your music files and greatly compress their file sizes with minimal quality loss.

The standalone program – taking just 323KB of disk space itself – opens up to a window with a simple interface. First, you have to use the two buttons in the toolbar to add the MP3 files or a folder that you want to compress.

Once the files are listed in the main pane at the middle (complete with filename, song title, album, artist, bitrate and size), you can select or deselect which ones you want to edit.

Two sections at the bottom determine the kind of compression your file will go through. The ‘Bitrate’ section lets you select the type of mode (variable, constant, average), rate in kbps, and a preset (misspelt as ‘present’, and having four options: high quality, portable, compromise, very low quality). If you don’t know what you are doing when it comes to music editing, using these presets can be very handy.

The ‘Modus’ section gives you the option of figuring out the kind of output (mono, joint stereo, stereo and dual channels) and sample frequency – both of which can be adjusted directly through the preset.

Finally, choose a destination folder to save the newly-edited files to, and you’re done. Hit the ‘Start Process’ in the top toolbar and let the program do the rest. Quick, easy and very handy!

Rating: 3.5/5
Download: www.inspire-soft.net/?nav=soft_mp3qualitymodifier
Direct Download: www.inspire-soft.net/files/MP3QualityModifier1.0.zip
Size: 315.63KB

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Wednesday, June 24, 2009

Fotografix


Ultra-small, ultra-lightweight photo editor with an incredible number of options…


Adobe Photoshop and Gimp are great tools to have for anyone who likes to experiment with and edit images. However, these bulky software packages take up a lot of hard disk space and memory on your PC. So if you perform simpler tasks, such as cropping, small touches, etc, you can always opt to install something like Paint.NET .

Still, when it comes to portability, there is no software, which is worthwhile in this regard. There is a portable version of Gimp that you can carry around on your pen drive, but it’s very bulky and thus generally slow in actual usage.

Developer L. Madhavan decided to fill the void with his amazing new tool, Fotografix – a portable photo-editing application that requires no installation and takes up just 347KB of disk space!

Firing up the program, you are in for a surprise: At this light weight, the package still comes fully equipped with all of your regular image-manipulation tools, such as selection tools, brushes, clone tools, layer tools, etc.

Users of advanced software like Photoshop will have absolutely no issue in starting off, and will feel quite at home with Fotografix – a pane on the left with the necessary tools, the centre pane reserved for the photo and the right-most part has small windows to note your history and scripts.

Of course, it has its drawbacks. Those who like to freely crop their pictures will find the lasso tool sorely missing in this package, while the lack of keyboard and mouse shortcuts will irk power users.

But overall, this application misses out on very little from what is offered by the big guys; and considering its light -weight and zippy interface, it’s a must-have for your pen drive.

Rating: 4.5/5
Download: lmadhavan.com/software/fotografix/
Size: 347KB

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Model Livers to Replace Lab Rats


German researchers have developed an external model of the liver, which could provide a safer alternative to animal experiments

If you have fever, headaches or a cold, it’s only a short way to the nearest chemist. The drugs, on the other hand, can take up to eight to ten years to develop.

Animal testing has been an essential step in testing drugs, but it continues to raise ethical issues. Furhermore,
humans and animals have different metabolisms, and around 30 per cent of side effects come to light in trials following animal experiments.

Researchers at the the Fraunhofer Institute have developed a model of the liver, which is viable outside the body and is suitable for testing drugs.

“Our artificial organ systems offer an alternative to animal experiments,” said Heike Mertsching, Professor at the Interfacial Engineering and Biotechnology Institute at Fraunhofer.

The test system, which Professor Mertsching has developed jointly with Dr Johanna Schanz, should in future give pharmaceutical companies more security and shorten the path to developing and releasing new drugs.

“Our liver model is a functioning system of blood vessels,” said Dr. Schanz. “We don’t build artificial blood vessels, but use existing ones – from a piece of pig’s intestine.”

All of the pig cells are removed, but the blood vessels are preserved. Human cells are then seeded onto this structure – hepatocytes, which are responsible for breaking down drugs, and endothelial cells, which act as a barrier between blood and tissue cells.

In order to simulate circulation, the researchers put the model into a computer-controlled bioreactor with a flexible tube pump. This enables the nutrient solution to be fed in and carried away in the same way as in veins and arteries in humans.

“The cells were active for up to three weeks,” said Dr. Schanz. “This time was sufficient to analyse and evaluate the functions. A longer period of activity is possible, however.”

The researchers established that the cells work in a similar way to those in the body. They detoxify, break down drugs and build up proteins. These are important pre-conditions for drug tests or transplants, as the effect of a substance can change when transformed or broken down. Many drugs are only metabolised into their therapeutic active form in the liver, while others can develop poisonous substances.

At the moment, the test system is being examined. The researchers say it could provide an alternative to animal testing within two years.


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