How We Localize Surround Sound

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. The ability of humans and other animals to pinpoint the location of sound sources is remarkably good, scientists say. Since the early 1900s, many studies have been performed on the underlying physical mechanisms of how animals’ ears can determine “directional sound.” In a recent study and review, scientists Axel Michelsen and Ole Naesbye Larsen from the University of Southern Denmark have offered a quantitative analysis of how animals like insects and small birds can localize the direction to sound sources. These animals are too small to take advantage of the directional cues used by humans (changes with direction of the sound pressure and time of arrival of sound at the ears). However, the results of the study, which is published in a recent issue of Bioinspiration and Biomimetics, could have important implications for humans, as well.“We now have an understanding of the physics of these hearing systems, and can make quantitative predictions that can be tested in experiments,” Michelsen told PhysOrg.com.In order to determine where a sound is coming from, animals can use information based on the differences between two ears (called “binaural” cues) or information, such as from the shape, of a single ear (called “monaural” cues). Michelsen and Larsen explain that many smaller non-mammalian animals compute the azimuth (horizontal plane) of sound sources using binaural cues with ears that receive sound at both the outer and inner surface of the eardrum, which is called “pressure difference reception.”Birds and grasshoppers are some of the small animals that can use pressure difference reception, which is characterized by having two ears that are connected by an air tunnel through the animal’s body. As the sound travels between ears through the animal’s body, each eardrum is activated by different sounds at its outer and inner surface that help the animal determine the source of the sound. For example, the ear facing more toward the sound source vibrates with a larger amplitude than the eardrum facing away. As the researchers emphasize, both sound transmission through the body and binaural cues help the animal localize sound. Although scientists know the general mechanisms responsible for sound localization, the difficulty of performing experiments with animals in non-interfering environments makes a detailed model elusive. Michelsen and Larsen explain that scientists are still far from understanding certain components of directional hearing, such as the physics of sound transmission through channels in the body, and how an animal’s habitat influences its hearing mechanisms. “What is needed now is to get a much better understanding of directional hearing in the natural habitats, where thick vegetation, etc., degrade sounds,” Michelsen said.Humans, on the other hand, use a different type of sound receiver, one that uses simply “pressure reception.” In human ears, only the outer surface is exposed to sound, and an opening (the Eustachian tube) allows an equalization of pressure, but doesn’t allow sound to enter the middle ear. While humans with normal hearing have a surprisingly good ability to determine sound origins, individuals who use hearing aids often have only a very limited ability to localize sounds.But, as Michelsen and Larsen explain, using techniques from pressure difference reception, like the birds and grasshoppers have, may improve the sound localization ability of human hearing aids. One possibility is to let the hearing aids in the two ears exchange information by means of radio signals, which enhances the binaural and time cues in both ears, and thereby helps a user determine the direction of a sound. As Michelsen explains, the ability to determine the source of sound is not just a luxury, but often a necessary survival skill.“Praying mantids flying at night can hear the cries of hunting bats, but not determine the direction to the bats,” Michelsen said. “It probably means that more mantids get eaten by bats than would have been the case if their hearing system had been equipped with pressure difference reception.”Much more information remains to be learned about directional hearing in different animals. From frogs, which hear with their lungs and mouth, to crickets, which have ears on their front legs just below the knee, the ability to hear is complex and can offer a deeper understanding of nature’s remarkable acoustic abilities.More information: Michelsen, Axel, and Larsen, Ole Naesbye. “Pressure difference receiving ears.” Bioinsp. Biomim. 3 (2008) 011001 (18pp).Copyright 2007 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. The cricket’s ears are located on its front legs, and have four acoustic inputs. Sound first reaches the outer eardrum, which is connected to an acoustic trachea, a transverse trachea, and an acoustic trachea on the opposite side, allowing the sound to pass all the way through the cricket’s body. Credit: Michelsen and Larsen Citation: How We Localize Surround Sound (2008, January 9) retrieved 18 August 2019 from https://phys.org/news/2008-01-localize.htmlcenter_img Genetic hearing loss may be reversible without gene therapy You’re walking down a busy street, with cars and buses driving past and bits of conversations reaching your ears, when you hear someone call your name. You turn about 60 degrees to your left and look up to the second floor window of a building about 100 meters away, to exactly the spot where a friend is waving. 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Superconductor magnet spacecraft heat shield being developed

first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. (PhysOrg.com) — European space agencies and an aerospace giant are developing a new re-entry heat shield that will use superconductor magnets to generate a magnetic field strong enough to deflect the superhot plasma formed during re-entry of returning spacecraft. They plan to test the new technology by attaching a test module to a missile and using a Russian submarine to fire it into space. Citation: Superconductor magnet spacecraft heat shield being developed (2009, November 26) retrieved 18 August 2019 from https://phys.org/news/2009-11-superconductor-magnet-spacecraft-shield.html Explore furtherlast_img read more

Are some governments taking peak oil seriously

first_img More information: Terry Macalister and Lionel Badal, “Peak oil alarm revealed by secret official talks,” The Observer (August 22, 2010).Stefan Schultz, “‘Peak Oil’ and the German Government,” SPIEGEL ONLINE (September 1, 2010). World crude oil production may peak a decade earlier than some predict Those who contend that peak oil is a very real problem that we need to concerned about push for the development of alternative energy solutions that are renewable, and not in danger of eventual decline. Opponents of the idea of peak oil insist that we are nowhere near any point of decline, and that there is nothing to worry about. Some even call those bring attention to peak oil “alarmists.”However, it appears that some governments are starting to seriously consider the merits of peak oil. Publicly, officials in Britain’s Department of Energy and Climate Change downplay worries about Peak Oil. However, an adviser to the department has requested information about peak oil, and the Guardian reports that there was a peak oil workshop in the not-to-distant past that involved the DECC, Ministry of Defense and the Bank of England. Indications are that some officials in Britain really are considering the possible impacts of peak oil — and thinking about contingency plans should peak oil turn out to be disruptive on an economic and military scale.Britain isn’t the only government interested, either. In Germany, a military study addresses the possible impacts that peak oil could have. A leaked draft of the report by the Bundeswehr Transformation Center was seen by SPIEGEL ONLINE:It warns of shifts in the global balance of power, of the formation of new relationships based on interdependency, of a decline in importance of the western industrial nations, of the “total collapse of the markets” and of serious political and economic crises. While the leaked document was confirmed in its existence, German officials insist that it hadn’t been edited, and that it wasn’t meant to published. Even so, the existence of the report indicates that another government is concerned about the implications that peak oil, if we really are approaching such a point, could have on a worldwide scale.Whether or not you believe that peak oil is a pressing problem, it is interesting to note that some governments are starting to take the issue seriously — and even look for ways to avoid disaster that could come. Image source: Trevor MacInnis via Wikimedia Commons Explore further (PhysOrg.com) — One of the arguments that some bring up in defense of alternative energy is that of “peak oil.” The idea behind peak oil is that, as a fossil fuel in limited supply, eventually we will reach a point where oil production hits its maximum capability — and then begins to decline. Because there aren’t endless supplies of oil, and because it is a finite resource, the idea is that we will reach a tipping point at which it becomes impossible to continue increasing oil production. Some even contend that we’re already there. Citation: Are some governments taking ‘peak oil’ seriously? (2010, September 8) retrieved 18 August 2019 from https://phys.org/news/2010-09-peak-oil.html © 2010 PhysOrg.com This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

Is culture or cognition really responsible for language structure

first_img Historical context guides language development More information: Evolved structure of language shows lineage-specific trends in word-order universals, Nature (2011) doi:10.1038/nature09923 Explore further Citation: Is culture or cognition really responsible for language structure? (2011, April 14) retrieved 18 August 2019 from https://phys.org/news/2011-04-culture-cognition-responsible-language.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

PHD Comics hits the big screen

first_img © 2011 PhysOrg.com Explore further For the last year, grad students around the world have found themselves missing their regular comics, it now appears that creator Jorge Cham had a very good reason for the comic going MIA. He has been working with a team of grad students from California Institute of Technology, or Caltech, to create a live-action film where the characters of his comic strip come alive.Physorg.com spoke with Jorge Cham and learned that the movie was produced and directed by real-life graduate students from Caltech and the comic characters have been brought to life, not by professional actors, but grad students as well. The movie also features cameos by top scientists and professors including two MacArthur “Genius” Award winners.For those of you not familiar with the comic, it focuses on the lives of Cecilia, Mike Slakenerny, Tajel and the Nameless Grad Student. The comic and now the film, looks at the everyday life of a grad student. From research and more research to teaching, friendships and love, the movie presents young scientists as interesting characters and introduces the average person into what life is really like for a grad student.PHD Movie TrailerTelevision shows like the Big Bang Theory have increased the popularity of the scientist in recent years. While the Big Bang Theory is not completely true to life, the hopes of shows like this and of the new PhD Comic movie is to break the old stereotypical view of scientists. Starting September 15, the PhD Comic movie, “Piled Higher and Deeper” The Movie, is being screened worldwide on hundreds of academic campuses and Cham says they plan to send the movie to numerous film festivals as well. To see if the movie will be playing at a campus near you, check out his website for times and locations. (PhysOrg.com) — If you are a graduate student, you are more than likely aware of the popular Piled Higher and Deeper, or PHD, Comics created by Jorge Cham. These comics cover the everyday struggles that scientists face while in grad school in a humorous and accurate depiction. Citation: PHD Comics hits the big screen (2011, September 16) retrieved 18 August 2019 from https://phys.org/news/2011-09-phd-comics-big-screen.htmlcenter_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Facebook founder fodder for animated film (c) Jorge Chamlast_img read more

ZZFS team says file syncs can be more personal

first_img(PhysOrg.com) — Turn over tweaks, updates, and edits on your entire body of recent work, personal accounts, financial records, and legal communiqués to cloud services? Giants like Google might sport a smiley face if you do, but finding an alternative for home PC users has been a topic for researchers. A combined team from Carnegie Mellon and Microsoft Labs in Cambridge, England, have developed ZZFS, a system in prototype of software and hardware that would allow users to access files remotely, even when that home PC is sleeping. A user could use the Windows Explorer file browser to see all the files and folders on other computers with ZZFS installed. Data on one computer would be visible and accessible from any of the others. The file synching system is viewed as an alternative to trusting a third party with files. Whether using Microsoft Office or iTunes, this idea has files opened normally once retrieved over the Internet. Michelle Mazurek of Carnegie Mellon University presented the prototype at the Usenix File and Storage Technology conference in San Jose earlier this month, where sessions and presentations were all about storage-system research and newer directions. The title of the paper, “ZZFS: A hybrid device and cloud file system for spontaneous users”According to a report from Technology Review, the USB device Somniloquy is used along with the software to process network traffic autonomously. As the name suggests, the hardware device connects to the Internet, can awaken a PC from sleep mode, retrieve data and then power it back down. It has enough gigabytes of storage to cache the files. According to the authors of the study, “Somniloquy is more appropriate than Wake-onLAN (WoL) for mobile storage devices, because it operates through firewalls and NAT boxes, and it handles mobility across subnets.”The authors note that “Good execution of data placement, caching and consistency policies across a user’s personal devices has always been hard. Unpredictable networks, capricious user behavior with leaving devices on or off and non-uniform energy-saving policies constantly interfere with the good intentions of a storage system’s policies.”Their goal has been to find a way to better manage the “uncertainties.” They refer to their system as a distributed device and cloud file system for file access. More information: research.microsoft.com/pubs/15 … 1/ZZFSfinalpaper.pdf © 2011 PhysOrg.com Explore furtherlast_img read more

Making a molecular micromap Imaging the yeast 26S proteasome at nearatomic resolution

center_img Copyright 2012 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com. Journal information: Proceedings of the National Academy of Sciences Citation: Making a molecular micromap: Imaging the yeast 26S proteasome at near-atomic resolution (2012, September 24) retrieved 18 August 2019 from https://phys.org/news/2012-09-molecular-micromap-imaging-yeast-26s.html Explore further This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

New research suggests perovskite as cheaper replacement for siliconbased solar panels

first_img Simply meeting the same efficiency levels as silicon isn’t a big deal of course, other materials have been found that are capable of doing so as well, what’s newsworthy here is that using perovskite to make solar cells would be far cheaper. Not only is it more readily available, but it doesn’t require as much production cost. Also, cells that use it would require far less material. Silicon cells, for example, typically wind up approximately 180 micrometers thick. A comparable cell made using perovskite on the other hand would be just 1 micrometer thick.Perovskite isn’t some newly discovered material—scientists have known about it for over 170 years. What’s new is that researchers are only now beginning to fully realize its potential as a material for use in solar cell technology. It was only in 2009 that researchers first thought of using the semiconductor in such cells—initial testing indicated that it was only 3.5 percent efficient. Worse, it didn’t hold up for very long when used. But since that time, researchers have figured out how to make it last longer and have continuously improved its efficiency to boot.Current prototypes are made using a process that involves spraying the material on a base, which means the material is far more versatile than silicon as well. But what really has researchers exited are expectations for creating solar panels far more cheaply than can be done today—estimates suggest they could cost just 10 to 20 cents per watt, as compared to 75 cents per watt for traditional silicon based panels—fossil fuels cost an average of 50 cents per watts, suggesting that the use of perovskite could cause a dramatic shift to solar power in the future if its efficiency can be improved as researchers hope. More information: Oxford Photovoltaics: www.oxfordpv.com/photovoltaic-cell-technology.htmlvia MIT Tech Review This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Dye-sensitized solar cells rival conventional cell efficiency © 2013 Phys.orglast_img read more

Researchers use DNA strands to build decomposable nanostructures

first_img Journal information: Nature Nanotechnology Nanostructures made of DNA strands can encapsulate, release small-molecule drugs More information: DNA assembly of nanoparticle superstructures for controlled biological delivery and elimination, Nature Nanotechnology (2014) DOI: 10.1038/nnano.2013.309AbstractThe assembly of nanomaterials using DNA can produce complex nanostructures, but the biological applications of these structures remain unexplored. Here, we describe the use of DNA to control the biological delivery and elimination of inorganic nanoparticles by organizing them into colloidal superstructures. The individual nanoparticles serve as building blocks, whose size, surface chemistry and assembly architecture dictate the overall superstructure design. These superstructures interact with cells and tissues as a function of their design, but subsequently degrade into building blocks that can escape biological sequestration. We demonstrate that this strategy reduces nanoparticle retention by macrophages and improves their in vivo tumour accumulation and whole-body elimination. Superstructures can be further functionalized to carry and protect imaging or therapeutic agents against enzymatic degradation. These results suggest a different strategy to engineer nanostructure interactions with biological systems and highlight new directions in the design of biodegradable and multifunctional nanomedicine.Press release © 2014 Phys.org Explore further DNA can mediate the assembly of nanoparticles and polymers into multifunctional superstructures and control their interactions with biological systems, potentially allowing for applications in cancer imaging and drug delivery while mitigating the risks of toxicity associated with engineered nanomaterials. Credit: Leo Chou, Kyryl Zagorovsky, Warren Chancenter_img (Phys.org) —A team of researchers in Canada has found a way around the problem of large nanostructures that are used to combat tumors, remaining in the body after they are no longer needed. In their paper published in the journal Nature Nanotechnology, the team describes a technique they developed where they used DNA strands to tie together small nanostructures creating larger nanostructures, that over time—after a tumor had been reduced—broke down and left the body. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Citation: Researchers use DNA strands to build decomposable nanostructures (2014, January 27) retrieved 18 August 2019 from https://phys.org/news/2014-01-dna-strands-decomposable-nanostructures.html Over the past several years, researchers have discovered that nanostructures, built from nanoparticles can be used to deliver drugs directly to a tumor, killing it. This is preferential to chemotherapy because it harms only tumor cells, rather than healthy cells throughout the body. The down side is that the nanostructures are made of materials that are considered toxic if they build up in the body and worse, are a little too big for the body to break down and get rid of. Thus, the nanostructures remain after they are no longer needed. To get around this problem, the researchers took a very unique approach, they used DNA strands to tie small nanostructures together, creating a large enough structure to transport tumor killing drugs. But because they are tied together with DNA, they become untied as the body breaks down the DNA strands. Once loosed, the nanostructures revert back to groups of smaller structures which the body can process and get rid of.The concept was tested in mice, and results thus far indicate that the process worked as planned—the team was able to actually see the nanostructures as they appeared in the mouse urine, proving that the mice’s systems were able to remove the smaller sized nanostructures from the tumor site and pass them through to the renal system. The researchers report that their technique at this time shows promise, but of course, more work will have to be done to prove that the technique is safe, and that the nanostructures can hold together long enough to do their job. They believe their work will lead to new types of cancer killing agents, but they won’t be ready for use in humans for at least five to ten years.last_img read more

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