Einstein was right

Scientists on Friday said that an experiment which challenged Einstein's theory on the speed of light had been flawed and that sub-atomic particles -- like everything else -- are indeed bound by the universe's speed limit. Researchers working at the European Centre for Nuclear Research (CERN) caused a storm in 2011 when they published experimental results showing that neutrinos could out-pace light by some six kilometres (3.7 miles) per second. The findings threatened to upend modern physics and smash a hole in Albert Einstein's 1905 theory of special relativity, which described the velocity of light as the maximum speed in the cosmos. But CERN now says that the earlier results were wrong and faulty kit
was to blame. "Although this result isn't as exciting as some would have liked, it is what we all expected deep down," said the centre's research director Sergio Bertolucci.? "The story captured the public imagination, and has given people the opportunity to see the scientific method in action. "An unexpected result was put up for scrutiny, thoroughly investigated and resolved in part thanks to collaboration between normally competing experiments. That's how science moves forward."  The neutrinos were timed on thenear  journey from CERN's giant underground lab Geneva to the Gran Sasso Laboratory in Italy, after travelling 732 kilometres (454 miles) through the Earth's crust. To do the trip, the neutrinos should have taken 0.0024 seconds. Instead, the particles were recorded as hitting the detectors in Italy 0.00000006 seconds sooner than expected, the preliminary experiment had shown. Researchers updated the science community on Friday at the International Conference on Neutrino Physics and Astrophysics, being held in Japan's ancient capital of Kyoto. "The previous data taken up to 2011 with the neutrino beam from CERN to Gran Sasso were revised taking into account understood instrumental effects," the team said. "A coherent picture has emerged with both previous and new data pointing to a neutrino velocity consistent with the speed of light." The initial findings had been greeted with a combination of excitement and scepticism, even from those involved in the experiment, who urged other physicists to carry out their own checks to corroborate or refute what had been seen. "If this result at CERN is proved to be right, and particles are found to travel faster than the speed of light, then I am prepared to eat my shorts, live on TV," Jim Al-Khalili, a professor of theoretical physics at Britain's University of Surrey, declared at the time. Source: Hindustan Times, Image: flickr.com

Read More........→June 08, 2012

High-Speed Imaging Method Captures Entire Brain Activity

Credit: Research Institute Of Molecular Pathology

The team used the new system to simultaneously image the activity of every neuron in the worm Caenorhabditis elegans, as well as the entire brain of a zebrafish larva, offering a more complete picture of nervous system activity than has been previously possible. Head region and the majority of the brain of a zebrafish larvae, as recorded and reconstructed using the light-field microscope “The new method is an indispensible tool to understand how the brain represents and processes sensory information and how this leads to cognitive functions and behaviour,” says physicist Alipasha Vaziri, a joint group leader at the IMP and MFPL and head of the research platform „Quantum Phenomena & Nanoscale Biological Systems“ (QuNaBioS) of the University of Vienna, who led the project. “Because of the enormous density of the interconnection of nerve cells in the brain, relevant information is often encoded in states of this densely interconnected network of neurons rather than in the activity of individual neurons.”  Vaziri’s team developed the brain-mapping method together with researchers in the lab of Edward Boyden, an associate professor of biological engineering and brain and cognitive sciences at the Massachusetts Institute of Technology. High-speed functional 3-D imaging: Neurons encode information - sensory data, motor plans, emotional states, and thoughts - using electrical impulses called action potentials, which provoke calcium ions to stream into each cell as it fires. By engineering model organisms that carry fluorescent proteins which glow when they bind calcium, scientists can visualize this electrical firing of neurons in live animals. However, until now there has been no way to image this neural activity over a large volume, in three dimensions, and at high speed. Scanning the brain with a laser beam can produce 3-D images of neural activity, but it takes a long time to capture an image because each point must be scanned individually. The research-team wanted to achieve similar 3-D functional images but accelerate the process so they could see neuronal firing, which takes only milliseconds, as it occurs.
The new method is based on a technology known as light-field imaging, which creates 3-D images by capturing angular information of incoming rays of light. In the new paper, the researchers in Vienna and Cambridge built a light-field microscope which was optimized to have single neuron resolution and applied it, for the first time, to imaging of neural activity. With this kind of microscope, the light emitted by the sample is sent through an array of lenses that refracts the light in different directions. Each point of the sample generates about 400 different points of light, which can then be recombined using a computer algorithm to recreate 3-D structures. “Compared to existing methods, our new technology allows us to capture neuronal activity in volumes up to a thousand times larger at ten times higher speed”, says Robert Prevedel, a postdoc in the Vaziri Lab and first author of the paper. ”We have eliminated the need to scan multiple layers, thus the temporal resolution is only limited by the camera sensor and the properties of the molecules themselves.” Prevedel built the microscope at the IMP in Vienna. Young-Gyu Yoon, a graduate student at MIT and co-first author, devised the computational strategies that reconstruct the 3-D images. Neurons in action: The researchers used the technique to image neural activity in the worm C. elegans, the only organism for which the entire neural wiring diagram is known. This one-millimeter worm has 302 neurons, each of which the researchers imaged as the worm performed natural behaviors, such as crawling. To demonstrate the power of the new technology in higher organisms, they also studied larvae of zebrafish. Their nervous system consists of over 100 000 neurons that fire at a much faster rate, rather like humans. In the tiny larvae, the scientists were able to induce neuronal response to odor stimuli in around 500 neurons and track the nerve signals simultaneously in about 5000 activated neurons. The findings could be ultimately useful in developing new types of algorithms that simulate functions of the brain and predict behaviour. Such models are in high demand in the area of machine learning and object recognition and classification. The work in Vienna was funded by the Vienna Science and Technology Fund (WWTF), the Research Platform Quantum Phenomena and Nanoscale Biological Systems (QuNaBioS), the Human Frontiers Science Program, the European Commission, the VIPS Program of the Austrian Federal Ministry of Science and Research,the City of Vienna, and the Vienna Scientific Cluster (VSC).The IMP is funded by Boehringer Ingelheim. Contacts and sources: Research Institute Of Molecular Pathology, Citation: Prevedel R, Yoon Y-G, Hoffmann M, Pak N, Wetzstein G, Kato S, Schrödel T, Raskar R, Zimmer M, Boyden ES und Vaziri A. Simultaneous whole-animal 3D-imaging of neuronal activity using light-field microscopy. Nature Methods Advance Online Publication, 18 March, 2014. DOI 10.1038/nmeth.2964.High-Speed Imaging Method Captures Entire Brain Activity

Read More........→May 19, 2014