Avrupa’ya 150 yıldan beri 87 yeni tür örümceğin yerleştiği ve dünya ticaretinin yoğunluk kazanmasıyla da yeni örümceklerin giderek Avrupa’yı daha çok mesken tutacağı açıklandı.
Bern Üniversitesi Zooloji Enstitüsü araştırmacıları tarafından yapılan ve yayımlanan bir çalışmada, her iki yılda bir Avrupa’ya yeni bir tür örümcek geldiği ve bunun yakında her yıl bir örümcek rakamına ulaşacağı belirtilirken, genellikle Asya ülkelerinden gelen bu örümceklerin yerli örümceklere nazaran daha büyük olduğu kaydedildi.
Bunun nedeni, “yolculuğun stresine” büyük boy örümceklerin daha iyi dayanabilmesi olarak açıklanırken, yakın bir gelecekte her yıl yeni bir tür örümceğin Avrupa’ya gelmesinin beklendiğinin altı çizildi.Avrupa’da iklimin değişmesinin Asya’dan gelen örümceklere daha iyi bir yaşam koşulu sunduğu da belirtilen çalışmada, yeni türlerin gelişinin tehlikeli olabileceği de ima edildi.Çalışmada, şimdiye kadar Avrupa’da zehirli örümceğe rastlanmadığı da kaydedildi.
Saturday, November 17, 2007
Akdeniz’de köpekbalığını bekleyen tehdit
IUCN’nin açıklamasında, bölgede 30 türün soyunun tükenme tehlikesiyle karşı karşıya olduğu ve dünya genelinde en büyük yok olma tehdidiyle karşı karşıya olan köpek balığı ve kedi balığı türlerinin bu bölgede bulunduğu belirtildi. Açıklamada, Birliğin uzmanlarının 71 türü incelediği ve konuyla ilgili bir raporun yarın yayımlanacağı belirtildi.
Raporda, bu türlerin özellikle aşırı avlanmaları nedeniyle soyunun tükenebileceği kaydedildi. Türlerin soyunun tükenmesine yol açan nedenler arasında, çevre koşullarının kötüye gitmesi ve hobi amacıyla yapılan balıkçılık da yer aldı.IUCN’nin açıklamasında, derin sularda avlanmada uygulanacak bazı yasaklarla bu türlerin soyunun tükenmesinin engellenebileceği belirtildi.
Raporda, bu türlerin özellikle aşırı avlanmaları nedeniyle soyunun tükenebileceği kaydedildi. Türlerin soyunun tükenmesine yol açan nedenler arasında, çevre koşullarının kötüye gitmesi ve hobi amacıyla yapılan balıkçılık da yer aldı.IUCN’nin açıklamasında, derin sularda avlanmada uygulanacak bazı yasaklarla bu türlerin soyunun tükenmesinin engellenebileceği belirtildi.
Go with the flow-Traffic control Systems
Dr. Helbing, Professor of Sociology at the ETH Zurich Chair of Sociology, a specialist in modelling and simulation, supports his claim with a recent study called ‘Efficient Self-Control of Traffic Flows in Urban Networks Using Short-Sighted Anticipation’. Professor Helbing and co-author, Stefan Lämmer of the Institute for Transport and Economics at Dresden University of Technology, propose a self-organized control system for traffic lights that could improve vehicular traffic flow significantly. The system relies on the joining of two distinct strategies.
Traffic light system antiquated
The problem, Professor Helbing explains, is that heavy investments in traffic light systems were made in the 1960s and 70s rendering most systems today, due to use, age and technological advancement, antiquated. Forty to fifty years ago when traffic volume was lighter, the main job of traffic light systems was to manage peak traffic during the day or, for example, sporting events. The lights were centrally controlled, and not programmed to adjust in real time. Rather, they were mostly optimised for pre-established assumed situations, meaning for situations that traffic planners had faced in the past.
The disadvantage of this strategy, especially today, is that the more traffic lights there are to coordinate, the more difficult it is to optimize control of the lights. Why? The dilemma is well-known: the larger the number of nodes, or lights, in a system the more computation is necessary until finally computational time “explodes”. “Even for normal-sized cities, super computers are just not fast enough to compute all of the different options that exist for controlling traffic lights. So the number of choices actually considered by the optimization program is significantly reduced,” says Professor Helbing.
Most traffic lights, therefore, continue to be programmed offline, regardless of the realities of the road. Unfortunately, “the variation in the number of vehicles that queue up at a traffic light at any minute of the day is huge,” Professor Helbing says. None of this variation is considered when optimizing for typical Monday or Friday traffic volume curves. “You are optimizing for a situation that basically is true on average but that is never true for any single day or minute: essentially for a situation that never exists. Plus, even adaptive traffic lights in modern control schemes are usually restricted to a variation of cycle-based control.”
One strategy is not enough
Professor Helbing and Stefan Lämmer propose a decentralized system instead that would make travel time more predictable, though traffic light sequence less so. First, the researchers tried to optimize the flow of traffic at one light of an intersection. This localized approach worked well as long as traffic flow through the intersection was not too high. Once volume rose, however, locally programmed lights did not clear traffic off of side roads fast enough and led to back-ups at other intersections. Professor Helbing concluded “On its own, this optimizing strategy was worse than traffic light controls already in place.”
Another component, a stabilizing strategy, was then studied. This strategy cleared traffic when it reached a critical threshold, but it was inconsistent with travel time minimization. Unlike the optimization strategy, the stabilizing strategy performed poorly at all volumes. On its own, it too could not compete with today’s traffic light control systems.
However, “it turns out that the two strategies properly combined perform better than today’s traffic light controls at all traffic volumes. So the combination of two inferior strategies can perform much better – if we do it right,” Professor Helbing says.
Simulation tests show the combined strategies work well. With non-periodic - not cyclically repeated - traffic lights releasing long traffic queues, travel time even becomes more predictable. Flow is kept stable, fuel consumption and emissions are reduced.
Succes depends on motorists
However, the success of the new system will depend on how motorists react, Professor Helbing points out. Drivers are used to the present cycle of traffic lights and anticipate ‘their turn’ to enter an intersection. The combined strategy would disrupt such expectations: if the traffic load is heavy in one direction, that road will be served two times, while others will be served only once. To support driver acceptance and avoid undesirable side effects, such as increased frustration or even accidents, any new traffic control system would need government support and funding by way of a well-publicised awareness campaign directed to the general public during the system’s introductory phase.
In Asian countries, where infrastructure is still being built, is where Professor Helbing thinks investment in the combined strategies might first take place. In Europe the “pain and pressure for change may still not be great enough”. In the end, cost will be a determining factor. The new technologies will have to show that they are cheaper to run than the present system.
Testings ahead
The need to lower CO2 emissions could, however, accelerate the development, suggests Professor Helbing. “You have to decide whether it is necessary to force people to use their cars less, or if the same goals can be achieved through coordinating traffic flows better. If the answer is coordination, then let’s go for the better technology.”
Politicians need to be informed of the options. And the traffic light systems themselves must now be tested through practical application. Professor Helbing is nonetheless optimistic that they will out-perform the systems of today. “What we don’t know is how big an advantage the news systems will be. But all the facts point to decentralised traffic control. This will be the paradigm of the future.”
Traffic light system antiquated
The problem, Professor Helbing explains, is that heavy investments in traffic light systems were made in the 1960s and 70s rendering most systems today, due to use, age and technological advancement, antiquated. Forty to fifty years ago when traffic volume was lighter, the main job of traffic light systems was to manage peak traffic during the day or, for example, sporting events. The lights were centrally controlled, and not programmed to adjust in real time. Rather, they were mostly optimised for pre-established assumed situations, meaning for situations that traffic planners had faced in the past.
The disadvantage of this strategy, especially today, is that the more traffic lights there are to coordinate, the more difficult it is to optimize control of the lights. Why? The dilemma is well-known: the larger the number of nodes, or lights, in a system the more computation is necessary until finally computational time “explodes”. “Even for normal-sized cities, super computers are just not fast enough to compute all of the different options that exist for controlling traffic lights. So the number of choices actually considered by the optimization program is significantly reduced,” says Professor Helbing.
Most traffic lights, therefore, continue to be programmed offline, regardless of the realities of the road. Unfortunately, “the variation in the number of vehicles that queue up at a traffic light at any minute of the day is huge,” Professor Helbing says. None of this variation is considered when optimizing for typical Monday or Friday traffic volume curves. “You are optimizing for a situation that basically is true on average but that is never true for any single day or minute: essentially for a situation that never exists. Plus, even adaptive traffic lights in modern control schemes are usually restricted to a variation of cycle-based control.”
One strategy is not enough
Professor Helbing and Stefan Lämmer propose a decentralized system instead that would make travel time more predictable, though traffic light sequence less so. First, the researchers tried to optimize the flow of traffic at one light of an intersection. This localized approach worked well as long as traffic flow through the intersection was not too high. Once volume rose, however, locally programmed lights did not clear traffic off of side roads fast enough and led to back-ups at other intersections. Professor Helbing concluded “On its own, this optimizing strategy was worse than traffic light controls already in place.”
Another component, a stabilizing strategy, was then studied. This strategy cleared traffic when it reached a critical threshold, but it was inconsistent with travel time minimization. Unlike the optimization strategy, the stabilizing strategy performed poorly at all volumes. On its own, it too could not compete with today’s traffic light control systems.
However, “it turns out that the two strategies properly combined perform better than today’s traffic light controls at all traffic volumes. So the combination of two inferior strategies can perform much better – if we do it right,” Professor Helbing says.
Simulation tests show the combined strategies work well. With non-periodic - not cyclically repeated - traffic lights releasing long traffic queues, travel time even becomes more predictable. Flow is kept stable, fuel consumption and emissions are reduced.
Succes depends on motorists
However, the success of the new system will depend on how motorists react, Professor Helbing points out. Drivers are used to the present cycle of traffic lights and anticipate ‘their turn’ to enter an intersection. The combined strategy would disrupt such expectations: if the traffic load is heavy in one direction, that road will be served two times, while others will be served only once. To support driver acceptance and avoid undesirable side effects, such as increased frustration or even accidents, any new traffic control system would need government support and funding by way of a well-publicised awareness campaign directed to the general public during the system’s introductory phase.
In Asian countries, where infrastructure is still being built, is where Professor Helbing thinks investment in the combined strategies might first take place. In Europe the “pain and pressure for change may still not be great enough”. In the end, cost will be a determining factor. The new technologies will have to show that they are cheaper to run than the present system.
Testings ahead
The need to lower CO2 emissions could, however, accelerate the development, suggests Professor Helbing. “You have to decide whether it is necessary to force people to use their cars less, or if the same goals can be achieved through coordinating traffic flows better. If the answer is coordination, then let’s go for the better technology.”
Politicians need to be informed of the options. And the traffic light systems themselves must now be tested through practical application. Professor Helbing is nonetheless optimistic that they will out-perform the systems of today. “What we don’t know is how big an advantage the news systems will be. But all the facts point to decentralised traffic control. This will be the paradigm of the future.”
A discovery of a new way to manipulate light a million times more efficiently than before
Using a special hollow-core photonic crystal fibre, a team at the University of Bath, UK, has opened the door to what could prove to be a new sub-branch of photonics, the science of light guidance and trapping.
The team, led by Dr Fetah Benabid, reports on the discovery, which relates to the emerging attotechnology, the ability to send out pulses of light that last only an attosecond, a billion billionth of a second.
These pulses are so brief that they allow researchers to more accurately measure the movement of sub-atomic particles such as the electron, the tiny negatively-charged entity which moves outside the nucleus of an atom. Attosecond technology may throw light, literally, upon the strange quantum world where such particles have no definite position,only probable locations.
To make attosecond pulses, researchers create a broad spectrum of light from visible wavelengths to x-rays through an inert gas. This normally requires a gigawatt of power, which puts the technique beyond any commercial or industrial use.
But Dr Benabid’s team used a photonic crystal fibre (pcf), the width of a human hair, which traps light and the gas together in an efficient way. Until now the spectrum produced by photonic crystal fibre has been too narrow for use in attosecond technology, but the team have now produced a broad spectrum, using what is called a Kagomé lattice, using about a millionth of the power used by non-pcf methods.
“This new way of using photonic crystal fibre has meant that the goal of attosecond technology is much closer," said Dr Benabid, of the University of Bath’s Department of Physics, who worked with students Mr Francois Couny and Mr Phil Light, and with Dr John Roberts of the Technical University of Denmark and Dr Michael Raymer of the University of Oregon, USA.
“The greatly reduced cost and size of producing these phenomenally short and powerful pulses makes exploring matter at an even smaller detail a realistic prospect.”
Dr Benabid’s team has not only made an important step in applied physics, but has contributed to the theory of photonics too. The effectiveness of photonic crystal fibre has lain so far in its exploitation of what is called photonic band gap, which stops photons of light from “existing” in the fibre cladding and enabled them to be trapped in the inside core of the fibre.
Instead, the team makes use of the fact that light can exist in different ‘modes’ without strongly interacting. This creates a situation whereby light can be trapped inside the fibre core without the need of photonic bandgap. Physicists call these modes bound states within a continuum.
The existence of these bound states between photons was predicted at the beginning of quantum mechanics in the 1930s, but this is the first time it has been noted in reality, and marks a theoretical breakthrough.
The team, led by Dr Fetah Benabid, reports on the discovery, which relates to the emerging attotechnology, the ability to send out pulses of light that last only an attosecond, a billion billionth of a second.
These pulses are so brief that they allow researchers to more accurately measure the movement of sub-atomic particles such as the electron, the tiny negatively-charged entity which moves outside the nucleus of an atom. Attosecond technology may throw light, literally, upon the strange quantum world where such particles have no definite position,only probable locations.
To make attosecond pulses, researchers create a broad spectrum of light from visible wavelengths to x-rays through an inert gas. This normally requires a gigawatt of power, which puts the technique beyond any commercial or industrial use.
But Dr Benabid’s team used a photonic crystal fibre (pcf), the width of a human hair, which traps light and the gas together in an efficient way. Until now the spectrum produced by photonic crystal fibre has been too narrow for use in attosecond technology, but the team have now produced a broad spectrum, using what is called a Kagomé lattice, using about a millionth of the power used by non-pcf methods.
“This new way of using photonic crystal fibre has meant that the goal of attosecond technology is much closer," said Dr Benabid, of the University of Bath’s Department of Physics, who worked with students Mr Francois Couny and Mr Phil Light, and with Dr John Roberts of the Technical University of Denmark and Dr Michael Raymer of the University of Oregon, USA.
“The greatly reduced cost and size of producing these phenomenally short and powerful pulses makes exploring matter at an even smaller detail a realistic prospect.”
Dr Benabid’s team has not only made an important step in applied physics, but has contributed to the theory of photonics too. The effectiveness of photonic crystal fibre has lain so far in its exploitation of what is called photonic band gap, which stops photons of light from “existing” in the fibre cladding and enabled them to be trapped in the inside core of the fibre.
Instead, the team makes use of the fact that light can exist in different ‘modes’ without strongly interacting. This creates a situation whereby light can be trapped inside the fibre core without the need of photonic bandgap. Physicists call these modes bound states within a continuum.
The existence of these bound states between photons was predicted at the beginning of quantum mechanics in the 1930s, but this is the first time it has been noted in reality, and marks a theoretical breakthrough.
MIT: Remote-control nanoparticles deliver drugs directly into tumors
MIT scientists have devised remotely controlled nanoparticles that, when pulsed with an electromagnetic field, release drugs to attack tumors. The innovation, reported in the Nov. 15 online issue of Advanced Materials, could lead to the improved diagnosis and targeted treatment of cancer.
In earlier work the team, led by Sangeeta Bhatia, M.D.,Ph.D., an associate professor in the Harvard-MIT Division of Health Sciences & Technology (HST) and in MIT's Department of Electrical Engineering and Computer Science, developed injectable multi-functional nanoparticles designed to flow through the bloodstream, home to tumors and clump together. Clumped particles help clinicians visualize tumors through magnetic resonance imaging (MRI).
With the ability to see the clumped particles, Bhatia’s co-author in the current work, Geoff von Maltzahn, asked the next question: “Can we talk back to them?”
The answer is yes, the team found. The system that makes it possible consists of tiny particles (billionths of a meter in size) that are superparamagnetic, a property that causes them to give off heat when they are exposed to a magnetic field. Tethered to these particles are active molecules, such as therapeutic drugs.
Exposing the particles to a low-frequency electromagnetic field causes the particles to radiate heat that, in turn, melts the tethers and releases the drugs. The waves in this magnetic field have frequencies between 350 and 400 kilohertz—the same range as radio waves. These waves pass harmlessly through the body and heat only the nanoparticles. For comparison, microwaves, which will cook tissue, have frequencies measured in gigahertz, or about a million times more powerful.
The tethers in the system consist of strands of DNA, “a classical heat sensitive material,” said von Maltzahn, a graduate student in HST. Two strands of DNA link together through hydrogen bonds that break when heated. In the presence of the magnetic field, heat generated by the nanoparticles breaks these, leaving one strand attached to the particle and allowing the other to float away with its cargo.
One advantage of a DNA tether is that its melting point is tunable. Longer strands and differently coded strands require different amounts of heat to break. This heat-sensitive tuneability makes it possible for a single particle to simultaneously carry many different types of cargo, each of which can be released at different times or in various combinations by applying different frequencies or durations of electromagnetic pulses.
To test the particles, the researchers implanted mice with a tumor-like gel saturated with nanoparticles. They placed the implanted mouse into the well of a cup-shaped electrical coil and activated the magnetic pulse. The results confirm that without the pulse, the tethers remain unbroken. With the pulse, the tethers break and release the drugs into the surrounding tissue.
The experiment is a proof of principal demonstrating a safe and effective means of tunable remote activation. However, work remains to be done before such therapies become viable in the clinic.
To heat the region, for example, a critical mass of injected particles must clump together inside the tumor. The team is still working to make intravenously injected particles clump effectively enough to achieve this critical mass.
“Our overall goal is to create multifunctional nanoparticles that home to a tumor, accumulate, and provide customizable remotely activated drug delivery right at the site of the disease,” said Bhatia.
Co-authors on the paper are Austin M. Derfus, a graduate student at the University of California at San Diego; Todd Harris, an HST graduate student; Erkki Ruoslahti and Tasmia Duza of The Burnham Institute in La Jolla, CA; and Kenneth S. Vecchio of the University of San Diego.
The research was supported by grants from the David and Lucile Packard Foundation, the National Cancer Institute of the National Institutes of Health. Dervis was supported by a G.R.E.A.T fellowship from the University of California Biotechnology Research and Educational Program.
Written by Elizabeth Dougherty, Harvard-MIT Division of Health Sciences and Technology
In earlier work the team, led by Sangeeta Bhatia, M.D.,Ph.D., an associate professor in the Harvard-MIT Division of Health Sciences & Technology (HST) and in MIT's Department of Electrical Engineering and Computer Science, developed injectable multi-functional nanoparticles designed to flow through the bloodstream, home to tumors and clump together. Clumped particles help clinicians visualize tumors through magnetic resonance imaging (MRI).
With the ability to see the clumped particles, Bhatia’s co-author in the current work, Geoff von Maltzahn, asked the next question: “Can we talk back to them?”
The answer is yes, the team found. The system that makes it possible consists of tiny particles (billionths of a meter in size) that are superparamagnetic, a property that causes them to give off heat when they are exposed to a magnetic field. Tethered to these particles are active molecules, such as therapeutic drugs.
Exposing the particles to a low-frequency electromagnetic field causes the particles to radiate heat that, in turn, melts the tethers and releases the drugs. The waves in this magnetic field have frequencies between 350 and 400 kilohertz—the same range as radio waves. These waves pass harmlessly through the body and heat only the nanoparticles. For comparison, microwaves, which will cook tissue, have frequencies measured in gigahertz, or about a million times more powerful.
The tethers in the system consist of strands of DNA, “a classical heat sensitive material,” said von Maltzahn, a graduate student in HST. Two strands of DNA link together through hydrogen bonds that break when heated. In the presence of the magnetic field, heat generated by the nanoparticles breaks these, leaving one strand attached to the particle and allowing the other to float away with its cargo.
One advantage of a DNA tether is that its melting point is tunable. Longer strands and differently coded strands require different amounts of heat to break. This heat-sensitive tuneability makes it possible for a single particle to simultaneously carry many different types of cargo, each of which can be released at different times or in various combinations by applying different frequencies or durations of electromagnetic pulses.
To test the particles, the researchers implanted mice with a tumor-like gel saturated with nanoparticles. They placed the implanted mouse into the well of a cup-shaped electrical coil and activated the magnetic pulse. The results confirm that without the pulse, the tethers remain unbroken. With the pulse, the tethers break and release the drugs into the surrounding tissue.
The experiment is a proof of principal demonstrating a safe and effective means of tunable remote activation. However, work remains to be done before such therapies become viable in the clinic.
To heat the region, for example, a critical mass of injected particles must clump together inside the tumor. The team is still working to make intravenously injected particles clump effectively enough to achieve this critical mass.
“Our overall goal is to create multifunctional nanoparticles that home to a tumor, accumulate, and provide customizable remotely activated drug delivery right at the site of the disease,” said Bhatia.
Co-authors on the paper are Austin M. Derfus, a graduate student at the University of California at San Diego; Todd Harris, an HST graduate student; Erkki Ruoslahti and Tasmia Duza of The Burnham Institute in La Jolla, CA; and Kenneth S. Vecchio of the University of San Diego.
The research was supported by grants from the David and Lucile Packard Foundation, the National Cancer Institute of the National Institutes of Health. Dervis was supported by a G.R.E.A.T fellowship from the University of California Biotechnology Research and Educational Program.
Written by Elizabeth Dougherty, Harvard-MIT Division of Health Sciences and Technology
Kopya insanların türemesi an meselesi
Uluslararası toplumun, üreme amaçlı insan kopyalamayı (klonlama) yasaklamaya ya da muhtemel ayrımcılığa, hatta suistimale karşı gelecekte ortaya çıkabilecek klonlanmış insanların haklarını korumaya hazırlanması yönünde acilen bir anlaşmaya varması gerekebileceği bildirildi.
İrlanda Ulusal Üniversitesi İnsan Hakları Merkezi’nden Brendam Tobin ve ekibinin yayımladığı rapor, BM’nin üreme amaçlı kopyalamayı yasa dışı ilan etmekte başarısız olmasının, araştırmalardaki hızlı gelişmeler yüzünden kopyalanmış insanların ortaya çıkması ve çoğalmasının an meselesi olduğunu anlamına geldiğini ortaya koydu.Tobin, tedavi amaçlı denetimli kopyalama araştırmalarına izin verilirken, üreme amaçlı insan kopyalamasının yasa gücüyle dünya çapında yasaklanmasının en arzu edilen seçenek olduğunu söyledi.Brendam Tobin, uluslararası toplumun uzlaşma bulamamaya direnmesi halinde, sorumluluğu kabul etmesi ve kopyalanmış her bireyin aynı insan haklarından bütünüyle yararlanmasını sağlaması gerekebileceğini ifade etti.BM’nin, kopyalanmış insanlara saygı gösterilmesi ve kopyalanmış insanların ön yargı, suistimal ya da ayrımcılığa karşı koruması yönünde halkın duyarlılığını artırmak için büyük çaplı programlar başlatması gerekebileceğini de ifade etti.Fransa ve Almanya, BM’den üreme amaçlı kopyalama girişimlerine küresel bir yasak getirilmesini istemiş, ancak tedavi amaçlı klonlama deneylerine izin verilmesini talep etmişti.BM’deki tartışmalar sırasında, birçok hükümet bu görüşe sahip çıkmış, ancak aralarında ABD ve Vietnam’ın da bulunduğu bazı ülkeler amacı ne olursa olsun her türlü klonlama çalışmasına karşı çıkmıştı.
İrlanda Ulusal Üniversitesi İnsan Hakları Merkezi’nden Brendam Tobin ve ekibinin yayımladığı rapor, BM’nin üreme amaçlı kopyalamayı yasa dışı ilan etmekte başarısız olmasının, araştırmalardaki hızlı gelişmeler yüzünden kopyalanmış insanların ortaya çıkması ve çoğalmasının an meselesi olduğunu anlamına geldiğini ortaya koydu.Tobin, tedavi amaçlı denetimli kopyalama araştırmalarına izin verilirken, üreme amaçlı insan kopyalamasının yasa gücüyle dünya çapında yasaklanmasının en arzu edilen seçenek olduğunu söyledi.Brendam Tobin, uluslararası toplumun uzlaşma bulamamaya direnmesi halinde, sorumluluğu kabul etmesi ve kopyalanmış her bireyin aynı insan haklarından bütünüyle yararlanmasını sağlaması gerekebileceğini ifade etti.BM’nin, kopyalanmış insanlara saygı gösterilmesi ve kopyalanmış insanların ön yargı, suistimal ya da ayrımcılığa karşı koruması yönünde halkın duyarlılığını artırmak için büyük çaplı programlar başlatması gerekebileceğini de ifade etti.Fransa ve Almanya, BM’den üreme amaçlı kopyalama girişimlerine küresel bir yasak getirilmesini istemiş, ancak tedavi amaçlı klonlama deneylerine izin verilmesini talep etmişti.BM’deki tartışmalar sırasında, birçok hükümet bu görüşe sahip çıkmış, ancak aralarında ABD ve Vietnam’ın da bulunduğu bazı ülkeler amacı ne olursa olsun her türlü klonlama çalışmasına karşı çıkmıştı.
Preserving One Web
Increasingly, people connect to the Internet through mobile phones, video-game consoles, or televisions. The problem is that a lot of Internet content isn't available for all of these devices, and many websites crash when loaded on a mobile device. Tim Berners-Lee, director of the World Wide Web Consortium (W3C) and father of the Internet, worries that this is effectively cutting some people off from the information that is freely shared on the Internet. Speaking at the Mobile Internet World conference in Boston earlier this week, Berners-Lee said that the W3C is working on defining a set of standards that developers can use to build websites that work with mobile devices, as well as with desktop computers, so that the mobile Web doesn't break apart from the World Wide Web. This week, the W3C also launched a new tool that developers can use to test their websites for compatibility with mobile devices.
The overarching goal of the initiative, according to Berners-Lee, is to keep content available regardless of the devices available to a person. "I like being able to choose my hardware separately from choosing my software, and separately from choosing my content," Berners-Lee said at the conference. There needs to be just one Web, he explained, and it needs to work on phones.
Many websites are far from Berners-Lee's vision. Some developers don't have websites that work with mobile devices and don't make mobile versions of their sites, seeing this as an added technical headache. For developers who do want their websites to be available everywhere, a common practice is to build special versions of sites for mobile devices, with pared-down features and, sometimes, content.
In some parts of the world, the mobile phone is the primary way that people access the Internet, and content should be available to those people as much as it is to people using a desktop computer. The system doesn't work well for those in wealthier nations, either. Users with devices such as the iPhone want to be able to access sites from their mobile device at the full capability that the iPhone has, says Matt Womer, the W3C's mobile-Web-initiative lead for North America. Users don't want to see a pared-down site.
On the other hand, Womer notes that mobile-device users shouldn't be forced to download large images or be redirected to several different pages, since users pay by the kilobyte.
Mobile sites can also be hard to find, because there are no standards for creating domain names. Some sites use the prefix "mobile" instead of "www," for example, while other sites use the prefix "wap." Womer says that the result can be confusing for users, who shouldn't have to know to look for special prefixes. "I think in the end, what's best for the user is one URL that works everywhere," he says.
The W3C's current suggestion for people writing Web pages, Womer says, is to separate information about how to present content from the content itself. The content can be described through hypertext markup language (HTML), the language traditionally used to describe Web pages, while the presentation can be handled with separate style sheets. Womer says that the W3C is collecting information about devices so that developers can tailor the presentation to the capabilities of the hardware.
The W3C's new tool, called the mobileOK checker, will look over code to see how well it follows the W3C's guidelines. Womer says that the tool won't be able to assess everything--some things, such as determining the readability of text against a background color, require human judgment--but it will consider a great deal of variables and provide specific instructions for what needs to be fixed.
"The importance of standards cannot be overestimated," says Jon von Tetzchner, CEO of Opera Software, who is working with the W3C's mobile-Web initiative. In addition to making browsers for desktop computers and mobile devices, Opera makes browsers for the Nintendo Wii and other game systems. "To deal with the complexity that is out there, there can only be one Web," von Tetzchner says.
The overarching goal of the initiative, according to Berners-Lee, is to keep content available regardless of the devices available to a person. "I like being able to choose my hardware separately from choosing my software, and separately from choosing my content," Berners-Lee said at the conference. There needs to be just one Web, he explained, and it needs to work on phones.
Many websites are far from Berners-Lee's vision. Some developers don't have websites that work with mobile devices and don't make mobile versions of their sites, seeing this as an added technical headache. For developers who do want their websites to be available everywhere, a common practice is to build special versions of sites for mobile devices, with pared-down features and, sometimes, content.
In some parts of the world, the mobile phone is the primary way that people access the Internet, and content should be available to those people as much as it is to people using a desktop computer. The system doesn't work well for those in wealthier nations, either. Users with devices such as the iPhone want to be able to access sites from their mobile device at the full capability that the iPhone has, says Matt Womer, the W3C's mobile-Web-initiative lead for North America. Users don't want to see a pared-down site.
On the other hand, Womer notes that mobile-device users shouldn't be forced to download large images or be redirected to several different pages, since users pay by the kilobyte.
Mobile sites can also be hard to find, because there are no standards for creating domain names. Some sites use the prefix "mobile" instead of "www," for example, while other sites use the prefix "wap." Womer says that the result can be confusing for users, who shouldn't have to know to look for special prefixes. "I think in the end, what's best for the user is one URL that works everywhere," he says.
The W3C's current suggestion for people writing Web pages, Womer says, is to separate information about how to present content from the content itself. The content can be described through hypertext markup language (HTML), the language traditionally used to describe Web pages, while the presentation can be handled with separate style sheets. Womer says that the W3C is collecting information about devices so that developers can tailor the presentation to the capabilities of the hardware.
The W3C's new tool, called the mobileOK checker, will look over code to see how well it follows the W3C's guidelines. Womer says that the tool won't be able to assess everything--some things, such as determining the readability of text against a background color, require human judgment--but it will consider a great deal of variables and provide specific instructions for what needs to be fixed.
"The importance of standards cannot be overestimated," says Jon von Tetzchner, CEO of Opera Software, who is working with the W3C's mobile-Web initiative. In addition to making browsers for desktop computers and mobile devices, Opera makes browsers for the Nintendo Wii and other game systems. "To deal with the complexity that is out there, there can only be one Web," von Tetzchner says.
Oil from Wood
Dutch biofuels startup Bioecon and Khosla Ventures have launched a joint venture called Kior, which will commercialize Bioecon's process for converting agricultural waste directly into "biocrude," a mixture of small hydrocarbon molecules that can be processed into fuels such as gasoline or diesel in existing oil refineries. The process, Kior claims, boasts numerous advantages over other methods of producing biofuels: it could prove relatively cheap, relies on a nontoxic catalyst, taps into the present fuel-refining and transportation infrastructure, and produces clean-burning fuels that can be used in existing engines.
Biofuels are widely seen as a key stepping-stone on the path from fossil fuels to renewable energy sources, particularly for transportation. Their use could also reduce emissions of carbon dioxide and other greenhouse gases. But ethanol, the most widely produced biofuel, contains little energy compared with gasoline or diesel. And a great deal of energy goes into its production: growing the grain from which it is fermented, distilling it, and transporting it. Many biofuels boosters have pinned their hopes on finding ways to produce ethanol from cellulose, the tough polymer that makes up much of plant stems and wood. In practice, though, cellulose must be broken down into simple sugars before it can be fermented into ethanol or converted into synthetic gas and turned into fuels. Despite three decades of research, these remain difficult, expensive, and energy-intensive processes that are not yet commercially viable. Additionally, recent research shows that ethanol, which is highly volatile, may actually exacerbate smog problems when it evaporates directly into the air instead of burning in vehicle engines.
The way to make cellulosic biofuels viable, says Bioecon's founder, Paul O'Connor, is to use catalysts to convert biomass into a hydrocarbon biocrude that can be processed into gasoline and diesel in existing petroleum refineries. After decades developing catalysts for the petroleum industry, O'Connor started Bioecon in early 2006 to develop methods for converting biomass directly into biofuels. His first success is a catalytic process that can convert cellulosic biomass into short-chain hydrocarbons about six to thirteen carbon atoms long. Khosla Ventures agreed to provide an undisclosed amount of series A funding to spinoff Kior in order to commercialize the process. Vinod Khosla, founder of the venture fund, believes that converting biomass into liquid transportation fuels is key to decreasing greenhouse-gas emissions and compensating for dwindling petroleum reserves. Khosla is funding a number of biofuels startups with competing technologies and says that Kior's approach is unique. "They have some very clever proprietary catalytic approaches that are pretty compelling," he says. "They can produce relatively cheap crude oil--that's attractive."
The most effective method of converting biomass into fuel is to subject it to high temperatures and high pressure to produce synthetic gas, or syngas. In the presence of a catalyst, the syngas reacts to produce fuels such as ethanol or methanol (used as an additive in biodiesel). But this is a costly process, and catalysts able to withstand the high temperature of the syngas are expensive and frequently toxic.
Attempts to produce fuel by directly exposing agricultural cellulose to a catalyst have had little success because most of the cellulose is trapped inside plant stems and stalks. O'Connor says that while the Bioecon researchers are developing new catalysts, their "biomass cracking" process is the real breakthrough. Using proprietary methods, they have been able to insert a catalyst inside the structure of the biomass, improving the contact between the materials and increasing the efficiency of the process. While O'Connor won't go into details, he says that the most basic version of the technique might involve impregnating the biomass with a solution containing the catalyst; the catalyst would then be recrystallized. "What we're doing now is improving the method to make it easier and cheaper," O'Connor says
Biofuels are widely seen as a key stepping-stone on the path from fossil fuels to renewable energy sources, particularly for transportation. Their use could also reduce emissions of carbon dioxide and other greenhouse gases. But ethanol, the most widely produced biofuel, contains little energy compared with gasoline or diesel. And a great deal of energy goes into its production: growing the grain from which it is fermented, distilling it, and transporting it. Many biofuels boosters have pinned their hopes on finding ways to produce ethanol from cellulose, the tough polymer that makes up much of plant stems and wood. In practice, though, cellulose must be broken down into simple sugars before it can be fermented into ethanol or converted into synthetic gas and turned into fuels. Despite three decades of research, these remain difficult, expensive, and energy-intensive processes that are not yet commercially viable. Additionally, recent research shows that ethanol, which is highly volatile, may actually exacerbate smog problems when it evaporates directly into the air instead of burning in vehicle engines.
The way to make cellulosic biofuels viable, says Bioecon's founder, Paul O'Connor, is to use catalysts to convert biomass into a hydrocarbon biocrude that can be processed into gasoline and diesel in existing petroleum refineries. After decades developing catalysts for the petroleum industry, O'Connor started Bioecon in early 2006 to develop methods for converting biomass directly into biofuels. His first success is a catalytic process that can convert cellulosic biomass into short-chain hydrocarbons about six to thirteen carbon atoms long. Khosla Ventures agreed to provide an undisclosed amount of series A funding to spinoff Kior in order to commercialize the process. Vinod Khosla, founder of the venture fund, believes that converting biomass into liquid transportation fuels is key to decreasing greenhouse-gas emissions and compensating for dwindling petroleum reserves. Khosla is funding a number of biofuels startups with competing technologies and says that Kior's approach is unique. "They have some very clever proprietary catalytic approaches that are pretty compelling," he says. "They can produce relatively cheap crude oil--that's attractive."
The most effective method of converting biomass into fuel is to subject it to high temperatures and high pressure to produce synthetic gas, or syngas. In the presence of a catalyst, the syngas reacts to produce fuels such as ethanol or methanol (used as an additive in biodiesel). But this is a costly process, and catalysts able to withstand the high temperature of the syngas are expensive and frequently toxic.
Attempts to produce fuel by directly exposing agricultural cellulose to a catalyst have had little success because most of the cellulose is trapped inside plant stems and stalks. O'Connor says that while the Bioecon researchers are developing new catalysts, their "biomass cracking" process is the real breakthrough. Using proprietary methods, they have been able to insert a catalyst inside the structure of the biomass, improving the contact between the materials and increasing the efficiency of the process. While O'Connor won't go into details, he says that the most basic version of the technique might involve impregnating the biomass with a solution containing the catalyst; the catalyst would then be recrystallized. "What we're doing now is improving the method to make it easier and cheaper," O'Connor says
Tiny, Sensitive Magnetic-Field Detectors
Researchers at the National Institute of Standards and Technology (NIST) have developed a new type of magnetometer--or magnetic-field detector--that rivals the sensitivity of its predecessors but is small and cheap, and uses very little power.
Magnetometers have a wide range of potential applications: where there is an electrical current, there is a magnetic field. Measurements of magnetic fields can reveal information about the electrical activity of the human heart and brain, the chemical identity of a spinning atom, or simply the presence or absence of metal. Because of their small size and sensitivity, the new sensors promise to improve detection of bombs and fetal heartbeats, and could be incorporated into future magnetic resonance imaging (MRI) scanners.
The new sensor, developed by NIST physicistJohn Kitching consists of a laser, a cell containing vaporized metal atoms, and a light detector. When the metal atoms are illuminated by the laser, they align such that they don't absorb any of the light. The presence of even a very weak magnetic field, however, disrupts their alignment, and they absorb some of the light. This change is recorded by the detector.
Other researchers have made similar magnetometers, but Kitching and his team used microfabrication techniques to miniaturize the vapor cell, which in their device consists of a cubic millimeter of silicon. The laser is an infrared diode similar to those in CD drives, so all three components can be mounted on silicon chips, making them easier to work with.
For applications such as the detection of improvised explosive devices or unexploded ordnance in minefields, the small size and low power consumption of the NIST sensors could make a big difference. The sensors could be grouped in arrays, making it possible to gain more data in a given amount of time. Commercially available laser-based magnetic detectors are the size of soda cans, require 20 watts of power, and cost $20,000 each, so grouping them in arrays is impracticable.
Remediation workers use these large sensors to detect unexploded land mines and other weapons in former battlefields, but it's a "tedious procedure," says Mark Prouty, president of Geometrics, a San Jose, CA, company that makes magnetic sensors. The heavy sensors must be carried back and forth across a field, then carried back to an office, where magnetic data is synthesized with GPS data to make maps. Then the workers must go back to the field with the maps to dig up the weapons.
With an array of smaller sensors, it would be possible to "gather data in a snapshot and dig [weapons] up in the field," says Prouty.
The detection of improvised explosive devices is also a big problem for the military, says Prouty. It's difficult to detect these bombs with individual magnetic sensors because "everything shows up, including the vehicle the sensor is mounted on," he explains. Single sensors take point measurements; they can detect a metal-containing object like a bomb but can't give any information about its location or shape. An array of magnetic sensors could "give an answer on the spot," says Prouty.
Magnetometers have a wide range of potential applications: where there is an electrical current, there is a magnetic field. Measurements of magnetic fields can reveal information about the electrical activity of the human heart and brain, the chemical identity of a spinning atom, or simply the presence or absence of metal. Because of their small size and sensitivity, the new sensors promise to improve detection of bombs and fetal heartbeats, and could be incorporated into future magnetic resonance imaging (MRI) scanners.
The new sensor, developed by NIST physicistJohn Kitching consists of a laser, a cell containing vaporized metal atoms, and a light detector. When the metal atoms are illuminated by the laser, they align such that they don't absorb any of the light. The presence of even a very weak magnetic field, however, disrupts their alignment, and they absorb some of the light. This change is recorded by the detector.
Other researchers have made similar magnetometers, but Kitching and his team used microfabrication techniques to miniaturize the vapor cell, which in their device consists of a cubic millimeter of silicon. The laser is an infrared diode similar to those in CD drives, so all three components can be mounted on silicon chips, making them easier to work with.
For applications such as the detection of improvised explosive devices or unexploded ordnance in minefields, the small size and low power consumption of the NIST sensors could make a big difference. The sensors could be grouped in arrays, making it possible to gain more data in a given amount of time. Commercially available laser-based magnetic detectors are the size of soda cans, require 20 watts of power, and cost $20,000 each, so grouping them in arrays is impracticable.
Remediation workers use these large sensors to detect unexploded land mines and other weapons in former battlefields, but it's a "tedious procedure," says Mark Prouty, president of Geometrics, a San Jose, CA, company that makes magnetic sensors. The heavy sensors must be carried back and forth across a field, then carried back to an office, where magnetic data is synthesized with GPS data to make maps. Then the workers must go back to the field with the maps to dig up the weapons.
With an array of smaller sensors, it would be possible to "gather data in a snapshot and dig [weapons] up in the field," says Prouty.
The detection of improvised explosive devices is also a big problem for the military, says Prouty. It's difficult to detect these bombs with individual magnetic sensors because "everything shows up, including the vehicle the sensor is mounted on," he explains. Single sensors take point measurements; they can detect a metal-containing object like a bomb but can't give any information about its location or shape. An array of magnetic sensors could "give an answer on the spot," says Prouty.
'Speed of thought' guides brain's memory consolidation
November 16, 2007 - Research shows the brain's processing speed is significantly faster than real timeScientists at The University of Arizona have added another piece of the puzzle of how the brain processes memory.Bruce McNaughton, a professor of psychology and physiology, and his colleague David Euston have shown that, during sleep, the reactivated memories of real-time experiences are processed within the brain at a higher rate of speed. That rate can be as much as six or seven times faster, and what McNaughton calls "thought speed."Memory stores patterns of activity in modular form in the brain's cortex. Different modules in the cortex process different kinds of information - sounds, sights, tastes, smells, etc. The cortex sends these networks of activity to a region called the hippocampus. The hippocampus then creates and assigns a tag, a kind of temporary bar code, that is unique to every memory and sends that signal back to the cortex.Each module in the cortex uses the tag to retrieve its own part of the activity. A memory of having lunch, for example, would involve a number of modules, each of which might record where the diner sat, what was served, the noise level in the restaurant or the financial transaction to pay for the meal.But while an actual dining experience might have taken up an hour of actual time, replaying the memory of it would only take 8 to 10 minutes. The reason, McNaughton said, is that the speed of the consolidation process isn't constrained by the real world physical laws that regulate activity in time and space.The brain uses this biological trick because there is no way for all of its neurons to connect with and interact with every other neuron. It is still an expensive task for the hippocampus to make all of those connections. The retrieval tags the hippocampus generates are only temporary until the cortex can carry a given memory on its own."It's a slow process," said McNaughton."The initial creation of the tag is made through existing connections. In order to do the rewiring necessary to have the intermodular connections carry the burden takes time. What you have to do is reinstate those memories multiple times. Every time you reinstate the memory, the modules make a little shift in the connection . . . something grows this way, grows that way, a connection gets made here, gets broken there. And eventually, after you do this multiple times, then an optimal set of connections gets constructed," Mc Naughton said.The brain is generally thought to do all of this during sleep, specifically slow-wave sleep, when the brain is not busy with processing real-time inputs. McNaughton has developed the technology to record from multiple probes, each of which can track the activity of a dozen or more brain cells."We need groups of cells because in order to identify a pattern, you have to look at the collected activity of many neurons," McNaughton said. His previous research has show that cells that fired during activity prior to sleep, also fired in the same sequential patterns during sleep. During sleep, the hippocampus sends little, 100-millisecond bursts of activity to the cortex as much as three times per second.What remains is finding an experiment that will enable researchers to demonstrate that changes in the memory reactivation process would affect memory consolidation but not damage the brain in the process."The more practical point, I think, is that this methodology, the ability to measure how fast the brain is processing at the level of changing the state of the brain from one 10- millisecond epoch to the next, how fast the internal state is sweeping through its memories or its allowable patterns is, I think, a model for thought speed," McNaughton said.Knowing the determinants for the speed of thought, he said, might allow studies of the effects of drugs, developmental anomalies and the behavioral therapies that might improve them.
Friday, November 16, 2007
Japonlardan “sağlık-ölçer” telefon
Japonya’da kullanıcısının nabzını ve kolestrolünü ölçen, stres seviyesini azaltmak için sohbet eden, ve ağız kokusuna karşı uyaran bir telefon üretildi.
Japonya’da NTT DoCoMo Inc. ve Mitsubishi ortaklığında üretilen cep telefonu, yoğun stres altında çalışırken sağlığını da ihmal etmek istemeyenlere hitap ediyor.
Kullanıcı “Wellness Phone”u vücudundaki yağ oranını tesbit etmek için de kullanabiliyor. Telefondaki sensör parmak ucundan nabzı ölçüyor.
Telefonun bir de “breathanalyzer” (nefes analizi) özelliği bulunuyor. Üzerinde bulunan ufak deliğe 3 saniye boyunca üflendiğinde, telefon ekranında ağız kokusu olup olmadığına dair bir mesaj gösteriyor.
Wellness Phone, “Kendinizi aşırı halsiz hissediyor musunuz?”, “Geceyarısınan sonra mı uyuyorsunuz?” gibi sorularla stres seviyesini de belirliyor ve ekranda “Üzülme, yarın yeni bir gün olacak!” mesajıyla da kullanıcısına destek oluyor.
Japonya’da NTT DoCoMo Inc. ve Mitsubishi ortaklığında üretilen cep telefonu, yoğun stres altında çalışırken sağlığını da ihmal etmek istemeyenlere hitap ediyor.
Kullanıcı “Wellness Phone”u vücudundaki yağ oranını tesbit etmek için de kullanabiliyor. Telefondaki sensör parmak ucundan nabzı ölçüyor.
Telefonun bir de “breathanalyzer” (nefes analizi) özelliği bulunuyor. Üzerinde bulunan ufak deliğe 3 saniye boyunca üflendiğinde, telefon ekranında ağız kokusu olup olmadığına dair bir mesaj gösteriyor.
Wellness Phone, “Kendinizi aşırı halsiz hissediyor musunuz?”, “Geceyarısınan sonra mı uyuyorsunuz?” gibi sorularla stres seviyesini de belirliyor ve ekranda “Üzülme, yarın yeni bir gün olacak!” mesajıyla da kullanıcısına destek oluyor.
Himalayalar karbondioksit ‘pompalıyor’
Fransızların Nancy üniversitesinden araştırmacılar, kıtasal erozyonun yeryüzü karbondioksit çevriminde çok önemli yer tuttuğunu gösterdi. İnsanoğlunun faaliyetleri sonucu atmosfere salınan karbon gazları yüzünden dengesi artık bozulmaya yüz tutan bu çevrimde, yanardağ patlamalarıyla yayılan karbondioksit biyokimyasal süreçlerle yok ediliyor.
Fransızların araştırmasına göre, Himalayaların erozyonu sonucu açığa çıkan organik karbonun küçük bir kısmı atmosfere karışıyor ve yüzde 70 ila 85’i, şiddetli yağmurlar ve nehirlerle Bengal körfezinde birikiyor. Bu da, yeryüzündeki bütün okyanuslara karalardan akan organik karbonun yüzde 10 ila 20’sini oluşturuyor.Himalaya gibi genç dağ zincirlerinde erozyonun fazla olduğunu belirleyen uzmanlar, muson yağmurları ve nehirlerle Himalayalardan yılda 1 milyar tondan fazla toprak ve organik maddenin okyanusa taşındığını düşünüyor ve bunu, Dünya’yla Ay arasındaki uzaklığın birbuçuk katı mesafeye kamyonların kum taşımasına benzetiyor.Araştırmacılar, bu manzaradan şu sonucu çıkarıyor: Himalayaların güney eteklerindeki havzalar, topraktaki organik maddeleri okyanusa taşıyor, okyanus dibinde biriken organik atıklar zamanla bozunuyor ve okyanustan atmosfere karbondioksit “pompalanıyor.”Milyonlarca yıla yayılan bu süreç, iklimin soğumasına yardımcı oluyor.
Fransızların araştırmasına göre, Himalayaların erozyonu sonucu açığa çıkan organik karbonun küçük bir kısmı atmosfere karışıyor ve yüzde 70 ila 85’i, şiddetli yağmurlar ve nehirlerle Bengal körfezinde birikiyor. Bu da, yeryüzündeki bütün okyanuslara karalardan akan organik karbonun yüzde 10 ila 20’sini oluşturuyor.Himalaya gibi genç dağ zincirlerinde erozyonun fazla olduğunu belirleyen uzmanlar, muson yağmurları ve nehirlerle Himalayalardan yılda 1 milyar tondan fazla toprak ve organik maddenin okyanusa taşındığını düşünüyor ve bunu, Dünya’yla Ay arasındaki uzaklığın birbuçuk katı mesafeye kamyonların kum taşımasına benzetiyor.Araştırmacılar, bu manzaradan şu sonucu çıkarıyor: Himalayaların güney eteklerindeki havzalar, topraktaki organik maddeleri okyanusa taşıyor, okyanus dibinde biriken organik atıklar zamanla bozunuyor ve okyanustan atmosfere karbondioksit “pompalanıyor.”Milyonlarca yıla yayılan bu süreç, iklimin soğumasına yardımcı oluyor.
Küresel Isınma ve Buz Dağları
Antartika Okyanusu’nda son 10 yıldır yüksek sıcaklıklar nedeniyle buz kütleleri giderek daha sık ana karadan kopuyor. Bu da buz dağlarının sayılarında artış görüldüğü anlamına geliyor.Bu buz dağlarının çevreye ne gibi etkileri olduğu üzerine ilk kez bir araştırma yapıldı. Science dergisinde yayımlanan bu araştırmaya göre, aslında buz dağları çevre üzerinde olumlu bir rol oynuyorlar. Araştırmayı yürüten bilim adamları, buz dağlarının eridikleri sırada demir yönünden zengin bir madde saçtığını söylüyor. Bu madde deniz canlılarını kendisine çeken bir plankton türünün yetişmesini sağlıyor.Bilim adamları buz dağları üzerinde kuş, balık, yosun ve kril gruplarının yaşadığını tespit etti. Bu eko sistemler, özellikle de yosun ve kril, atmosferdeki karbondioksitin emilmesine büyük oranda yardımcı olabilir. Çalışmanın baş yazarlarından Doktor Ken Smith, araştırmanın henüz ilk aşamalarında olduğunu söylüyor. Ancak buz dağlarının karbondioksit gazı üzerindeki etkisinin şüphe götürmez olduğunu ifade ediyor. Araştırmada yer alan bilim adamları, çalışmalarını iki büyük buz dağını inceleyerek tamamlamış. İncelemeler, buz dağlarının hayli uzağında, deniz altında bir araç kullanılması süretiyle gerçekleştirilmiş. Ve araştırmaları ışığında, bu buz dağlarının çevresinde üç kilometrelik alan boyunca kuşların ve deniz canlılarının biriktiği tespit edilmiş.
New battery technology converts sugar water into electricity
Researchers at St. Louis University in Missouri have developed a type of fuel cell that can produce electricity from almost any type of sugar. The scientists successfully tested the new cell with a glucose solution, carbonated soft drinks, sweetened drink mixes and even tree sap.The biodegradable cell runs best off of the simple glucose solution, and it runs worst off of carbonated beverages, which caused it to weaken.The research was funded by the Department of Defense, which is interested in developing ways to charge portable electronic devices in battlefield or emergency situations where electricity is not readily available. But the researchers have also suggested that the fuel cell could be used to replace lithium-ion batteries in portable electronics such as computers and cell phones. Lead researcher Shelley Minteer estimates that the cell could be ready for consumer use within three to five years.Fuel cells are distinct from the electrochemical cells commonly used in batteries; electrochemical cells generate electricity from a closed system (metal rods in ionic solutions), whereas fuel cells actually consume their fuel source, which must be periodically replaced. The cell developed by Minteer's team consumes sugar and leaves behind a handful of byproducts, primarily water. The researchers have suggested that a battery constructed from the cell could contain easily replaceable cartridges filled with a sugar solution.Minteer said that she has successfully used the prototype battery -- about the size of a postage stamp -- to power a handheld calculator.Fuel cells running off of hydrogen or hydrocarbons have become a popular area of alternative energy research -- but, in many cases, technical problems have ruled them out as a practical energy source. The smallest commercially available fuel cell is one made by Toshiba, which uses undiluted methanol as fuel. In December 2006, Samsung announced that it would make methanol fuel cells for laptops commercially available by the end of this year.
Butterflies inspire new LED illumination technology
An ingenious method of efficiently emitting light has come from a unique inspiration: butterflies.
The science behind higher-emission light emitting diodes (LED) comes from the fluorescent patches found on the wings of the African swallowtail butterfly. LED technology has been around for decades, but this new method of LED manufacture allows the diode to shine brighter.
The realization for the new form of diode comes from the wing structure of the butterfly. African swallowtails are dark colored with small spots of bright blue or green on their wings. The wings have scales that act like photonic crystals that provide intense fluorescent light. The scales have mirrors under them to direct light. With the butterflies, pigment in their wings absorbs ultra-violet light and emits it as a bright blue-green shade. The butterflies use the scales to signal to each other.
For the LEDs, scientists at MIT used actual photonic crystals to get the same effect. A lattice design etched into the crystals, implanted in the upper levels of LED’s design, makes the light emitted shine brighter.
LED technology has made advances to a point where LEDs could soon emit enough light to be considered an alternative to incandescent light bulbs. While LEDs are much more expensive, they also last a lot longer: approximately 100,000 hours. It also would save energy compared to conventional lighting.
LEDs date back to the 1950s, when an engineer at RCA observed that gallium arsenide emits an infrared light. The first infrared LED was developed soon afterward in 1961 by engineers at Texas Instruments, who accomplished this by electrifying gallium arsenide. A year later, the first visible-light LEDs appeared thanks to Nick Holonyak, Jr. of General Electric.
The most popular material for LEDs today is still gallium arsenide – which is used to make red and infrared LEDs – but gallium phosphide and gallium nitrite is used for other colors. LEDs are used for electronic signage, traffic lights and car taillights, among other uses.
The science behind higher-emission light emitting diodes (LED) comes from the fluorescent patches found on the wings of the African swallowtail butterfly. LED technology has been around for decades, but this new method of LED manufacture allows the diode to shine brighter.
The realization for the new form of diode comes from the wing structure of the butterfly. African swallowtails are dark colored with small spots of bright blue or green on their wings. The wings have scales that act like photonic crystals that provide intense fluorescent light. The scales have mirrors under them to direct light. With the butterflies, pigment in their wings absorbs ultra-violet light and emits it as a bright blue-green shade. The butterflies use the scales to signal to each other.
For the LEDs, scientists at MIT used actual photonic crystals to get the same effect. A lattice design etched into the crystals, implanted in the upper levels of LED’s design, makes the light emitted shine brighter.
LED technology has made advances to a point where LEDs could soon emit enough light to be considered an alternative to incandescent light bulbs. While LEDs are much more expensive, they also last a lot longer: approximately 100,000 hours. It also would save energy compared to conventional lighting.
LEDs date back to the 1950s, when an engineer at RCA observed that gallium arsenide emits an infrared light. The first infrared LED was developed soon afterward in 1961 by engineers at Texas Instruments, who accomplished this by electrifying gallium arsenide. A year later, the first visible-light LEDs appeared thanks to Nick Holonyak, Jr. of General Electric.
The most popular material for LEDs today is still gallium arsenide – which is used to make red and infrared LEDs – but gallium phosphide and gallium nitrite is used for other colors. LEDs are used for electronic signage, traffic lights and car taillights, among other uses.
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