Citation: Safari 5.0.1 brings plethora of extensions, patches vulnerabilities (2010, July 29) retrieved 18 August 2019 from https://phys.org/news/2010-07-safari-plethora-extensions-patches-vulnerabilities.html (c) 2010 PhysOrg.com The new and improved net application has downloadable features for the browser and a Safari reader that allows multiple web pages in a single window without the lag you might normally experience, among other perks. The new Safari 5.0.1 can be accessed from Safari or a dedicated Apple website, with many extension categories such as News, Entertainment, Search Tools, Social Networking, Shopping and more. With the click of the mouse, extensions can be downloaded directly from the gallery without re-starting the browser.Though, some have noted a lull in certain buttons still not up to par, one of the bigger complaints regarding Safari 5, is the extensions’ slow-load time and the ever-looming fear the tabs would lock or close when more than one is open at a time. There are still certain obstacles with some extensions, such as the lull or testy buttons, Apple addressed the performance issues head on and seem to have made a dent in the vulnerability department overall. One major issue de-bugged in particular is the Auto Fill feature that may have contributed to the use of personal data harvesting by hijackers, which will give all Safari users peace of mind when browsing.With competitors such as Google Chrome, Firefox, and Internet Explorer, Safari fights to see the number one spot, and with Apple developers continuously working to improve already sustainable versions, it may very well happen. 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. Explore further Apple Announces Safari 4 Browser (PhysOrg.com) — After the release of Safari 5 last month, Thursday, July 28th, Apple introduced a smoother, more efficient version, deeming it Safari 5.0.1.
(PhysOrg.com) — A senior astronomer with the Search for ExtraTerrestrial Intelligence (SETI) Institute, Dr Seth Shostak, has reported in an article published online that perhaps we should be seeking alien “life forms” that are thinking machines instead of concentrating the search on biological life forms. © 2010 PhysOrg.com Explore further Too risky to phone ET? Too late — NASA’s tried it More information: What ET will look like and why should we care, Acta Astronautica, Volume 67, Issues 9-10, November-December 2010, Pages 1025-1029. doi:10.1016/j.actaastro.2010.06.028 Dr Shostak said current experiments aiming to locate extraterrestrial intelligence all assume it is most likely to be found on “habitable worlds” with liquid surface water and light gaseous atmospheres, in other words, worlds that could support life similar biochemically to that on Earth. The problem with this assumption is that the development of artificial intelligence may come soon after the invention of communication technologies, as it has for us, which means SETI’s targeted searches may be “chasing a very short-lived prey,” Dr Shostak said. We have a chance of detecting extraterrestrial intelligences once they invent radio and go on the air, but within a few hundred years they are likely to invent their thinking machine successors.Like many other researchers, Shostak is unconcerned about the kind of extraterrestrial intelligence we find, and therefore restricting the search to biological life forms is unnecessarily limiting. The odds of finding artificial intelligence are greater than finding intelligent biological life, he said, although the decoding of any messages from a sentient machine might be more difficult than signals from a biological source.SETI has been searching for radio signals from other planets and moons for 50 years, and its researchers have realized that as our technology is rapidly advancing, so might that of other civilizations, so we are searching for an evolutionary moving target.Dr Shostak suggested the search for artificial intelligence should focus for at least some of the time on places were matter and energy are plentiful, such as young, hot stars, or near the center of galaxies, since these places would be of more interest to intelligent machines, even though they would be inhospitable for biological life forms.The article was published online in Acta Astronautica on 7 July. Shostak also presented his ideas in Daejeon in the Republic of Korea in October 2009 at the 60th International Astronautical Congress. Citation: SETI may be looking in the wrong places: astronomer (2010, August 24) retrieved 18 August 2019 from https://phys.org/news/2010-08-seti-wrong-astronomer.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.
(PhysOrg.com) — In a marketing strategy that can only be described as brilliant; brilliant enough to win the Media Grand Prix award at the Cannes Lions International Festival of Creativity, advertising agency Cheil Worldwide Seoul, conceived the idea of taking life size photographs of a clients grocery store items, pasting them on subway walls to make them look like grocery store shelves, and then allowing prospective shoppers to shop via snapping Quick Response (QR) codes with their cell phones, while waiting for their train. The current system is part of a three month advertising campaign, one which resulted in a 76% increase in registered members, and was meant to trim the lead rival E-Mart holds in the marketplace. No doubt the system will be expanded to full time if the increase in sales carries past the cost of placing the enormous billboards in the subway stations.If the strategy continues to pay off, it’s likely the same approach will be adopted by other vendors around the world and applied in a myriad of ways to entice buyers into buying goods wherever they may happen to be, standing, sitting or waiting. The client, Tesco’s, Home Plus, in South Korea, the second largest grocer in the country, found that after covering the walls of a single subway station with sharp clear pictures of their goods, their online sales increased 130%.The whole thing works using existing technology. First photographs are taken of entire grocery store sections; the photographs are then blown up to life-size renditions; then QR codes are applied. Next the photographs or billboards are pasted to the plastic back-lit wall sections already in place in a subway station. Home Plus members then simply walk up to a billboard and snap a picture of the QR code with their smart phone, which automatically adds the item to the customer’s virtual grocery cart. When finished shopping, the customer pays at the virtual checkout counter. The purchased items are then delivered directly to the customer’s home at the end of the work day, thus relieving them of having to stop for something on the way.The idea merges QR code technology, which has been in use for several years, chiefly as a means to allow customers to redeem virtual coupons, with online grocery shopping, which has been around for some fifteen years, taking what must assuredly be, a first step into a truly innovative marketing strategy. Explore further Citation: Grocery store chain mixes high and low tech to increase sales (2011, July 6) retrieved 18 August 2019 from https://phys.org/news/2011-07-grocery-chain-high-tech-sales.html © 2010 PhysOrg.com Google QR codes to appear in a store window near you (w/ Video) 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.
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. Research has shown as air temperatures rise, so too do ocean temperatures and as more carbon dioxide is released into the air, more of it is soaked up by oceans the world over, where it reacts to make carbonic acid. That in turn causes the water to have lowered pH levels which causes lowered levels of dissolved carbonate, which is what corals use to create their skeletons. The result seen thus far has been slowed coral growth.It was those skeletons that the team looked at in the waters off Australia’s west coast, specifically those of Porites. As corals grow over time, they create layers of skeleton material that can be read like tree rings to discern not just their age, but how much the coral grew each year. By drilling into some of the larger coral reefs, the team was able to trace the corals back hundreds of years. But it was the record of the last hundred that surprised them. Rather than finding slowed growth, such as has been seen with the Great Barrier Reef on the eastern part of the country, the growth in some areas of the southern sections had actually been growing at a faster rate than prior to the start of global warming.After more thought, the team has come to the conclusion that what they’ve found makes sense. The increased growth rates were found only in the more southern corals where water temperatures are generally cooler than in the north, thus, an increase in temperature would be more conducive to coral growth. But only up to a point. They believe once temperatures reach those of the north, the same slowed growth patterns seen elsewhere will appear.Interestingly, the team did not sample the ocean water at the sites where the coral samples were taken, and because of that, it’s not known if acidity levels in those areas that saw high growth rates had higher acidity levels or not. © 2011 PhysOrg.com Scientist creates new hypothesis on ocean acidification More information: Growth of Western Australian Corals in the Anthropocene, Science 3 February 2012: Vol. 335 no. 6068 pp. 593-596. DOI: 10.1126/science.1214570ABSTRACTAnthropogenic increases of atmospheric carbon dioxide lead to warmer sea surface temperatures and altered ocean chemistry. Experimental evidence suggests that coral calcification decreases as aragonite saturation drops but increases as temperatures rise toward thresholds optimal for coral growth. In situ studies have documented alarming recent declines in calcification rates on several tropical coral reef ecosystems. We show there is no widespread pattern of consistent decline in calcification rates of massive Porites during the 20th century on reefs spanning an 11° latitudinal range in the southeast Indian Ocean off Western Australia. Increasing calcification rates on the high-latitude reefs contrast with the downward trajectory reported for corals on Australia’s Great Barrier Reef and provide additional evidence that recent changes in coral calcification are responses to temperature rather than ocean acidification. (PhysOrg.com) — As most people are well aware, global warming isn’t just about the atmosphere, it’s about rising ocean temperatures as well. And like increases in the atmosphere, scientists aren’t really clear on what impact such temperature increases will have on the oceans. One such impact most researchers thought was well understood was the bleaching of coral reefs. As ocean temperatures rise and become more acidic, coral reefs tend to slough off the algae that grows on them, causing them to slowly die. Now however, new research by a team from the Australian Institute of Marine Science, has found that coral reefs off the western shores of the Australian continent are not only not suffering from the increased temperature, but are apparently thriving, as the study they’ve published in Science describes, they have actually been growing faster in the past hundred years than prior to that time. Journal information: Science Citation: Coral growth in Western Australia found to be thriving in warmer water (2012, February 3) retrieved 18 August 2019 from https://phys.org/news/2012-02-coral-growth-western-australia-warmer.html Explore further
Journal information: Biology Letters Vision regression is common in organisms that live in environments with limited light—there is no biological advantage if they can’t see anything anyway. Hearing regression, on the other hand, has not been studied very well. In this new effort, the researchers could find only one study that had been undertaken to find out if it even occurs. In that effort, the research team had found no differences in hearing abilities between the Mexican tetra and a type of Molly, compared to their surface lake cousins.To find out more, the researchers chose to study Amblyopsis spelaea and Typhlichthys subterraneus—blind fish that live in caves in Kentucky. They collected live samples of both, along with samples of Forbesichthys agassizii, a close cousin that lives in lakes in Tennessee.To test the hearing abilities of the fish, the researchers used brain scanners to note neural reaction to sounds being heard. The found that at low frequencies—up to 800 hertz—all three of the fish species could hear equally well. At higher frequencies, however, they found that the cave fish were virtually deaf compared to the surface fish. The researchers also found that the cave dwellers had just two-thirds as many hair cells in their ears as the surface fish.To find out why the cave dwelling fish might have lost hearing in such a specific range, the researchers ventured into the caves where they lived and monitored sound levels. They note that caves are much noisier places than most would expect, with running water and constant dripping—they found that the dominant sounds in the caves fell in the range that the fish that lived there could not hear. As with vision regression, there is no biological advantage to having a sense that doesn’t work at a certain range.The researchers note that previous studies have shown that some subterranean fish species have developed a sixth sense—an ability to detect water currents with their skin—as an adaption to their unique environments. That they say, could help them overcome both vision and hearing regression, helping them to survive in their dark and noisy environment. Explore further Typhlichthys subterraneus. Credit: Dante Fenolio, doi: 10.1098/rsbl.2013.0104 Darkness stifles reproduction of surface-dwelling fish (Phys.org) —A team of researchers made up of members from the U.S. and Canada has found that two species of fish that live in caves in the eastern and central parts of the United States have suffered hearing regression as a result of their environment—the first such example ever found. In their paper published in the journal Biology Letters, the group describes how they compared two species of cave dwelling fish with a close cousin that lives in a surface lake, and found that the subterranean dwellers had lost the ability to hear some high frequency sounds. Citation: Study finds first example of auditory regression in a subterranean organism (2013, March 28) retrieved 18 August 2019 from https://phys.org/news/2013-03-auditory-regression-subterranean.html More information: Evidence for hearing loss in amblyopsid cavefishes, Biology Letters, Published 27 March 2013 doi: 10.1098/rsbl.2013.0104AbstractThe constant darkness of caves and other subterranean habitats imposes sensory constraints that offer a unique opportunity to examine evolution of sensory modalities. Hearing in cavefishes has not been well explored, and here we show that cavefishes in the family Amblyopsidae are not only blind but have also lost a significant portion of their hearing range. Our results showed that cave and surface amblyopsids shared the same audiogram profile at low frequencies but only surface amblyopsids were able to hear frequencies higher than 800 Hz and up to 2 kHz. We measured ambient noise in aquatic cave and surface habitats and found high intensity peaks near 1 kHz for streams underground, suggesting no adaptive advantage in hearing in those frequencies. In addition, cave amblyopsids had lower hair cell densities compared with their surface relative. These traits may have evolved in response to the loud high-frequency background noise found in subterranean pools and streams. This study represents the first report of auditory regression in a subterranean organism. © 2013 Phys.org 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.
Explore further Citation: Startup touts ultrafast charging: What if a smartphone could charge in 12 minutes instead of two hours? (2013, April 8) retrieved 18 August 2019 from https://phys.org/news/2013-04-startup-touts-ultrafast-smartphone-minutes.html (c) 2013 Phys.org/Naveena Sadasivam Two Gadgets, One Charger: Fueltank Portable Lithium Ion Battery (Phys.org) —Potential Difference Inc., a Nevada startup, has developed a versatile charger that it claims can refill the batteries in smartphones, laptops and even electric vehicles to 80 percent capacity in 12 minutes. That’s a major improvement considering the Tesla Motors Supercharger needs 30 minutes to recharge 50 percent of a battery. An Exide forklift truck battery being charged using the rapid charging system. Credit: Potential Difference Inc. Dr. Yi Ding at the Georgia Institute of Technology first developed the technology in the late 1990s, and patented it in 2001. Now, Elliott Small, the CEO of Potential Difference, has acquired an exclusive license to commercialize the technology. “We are working on partnering with manufacturers to integrate the technology with the battery of different consumer electronics,” said Small. Potential Difference has already teamed up with Chargetek to manufacture the integrated circuits with the patented technology and is currently running a crowd funding campaign on Indiegogo.com.Predominantly, energy storage research involves innovation in the materials used to design batteries and in their physical configuration. But this particular technology modifies the method of charging without altering batteries themselves. The charger has sensors to detect the temperature, voltage and current charge level of a battery, and these data are used to determine the battery charge acceptance. Generally, batteries charge faster at low charge levels as compared to when they are already partially charged. By first determining the state of the battery, the charger can optimize the current pulses it sends.”This is what makes it unique and different,” said Scott Moura, a postdoctoral fellow in control systems and dynamics at the University of California, San Diego. “Batteries normally charge using a constant current but these chargers send current pulses.” Potential Difference has conducted testing on charger prototypes for lithium-ion batteries and its results show that common consumer electronics and electric vehicles can be charged fully within 16 minutes. While charging to 80 percent, the battery reached a maximum temperature of 42 degrees Celsius. A major plus for implementation is that the charger is compatible with almost all consumer electronics. “The interface that connects the charger and device needs to be changed, but the charger remains essentially the same,” Small said. Originally, Potential Difference hoped to manufacture the chargers on its own but technological and market limitations pushed the company to connect with electronics manufacturers. John Busbee, the CEO of Xerion Advanced Battery Corp., agrees that the charger will work best if customized to each electronic device. “It won’t reach it’s best potential without partnerships with the consumer electronics and battery manufacturers,” said Busbee. “If the battery model is not reflective of the battery, it’ll work, but it won’t work as well.” However, Ding argues that the charging method is generic and depends mainly on basic battery chemistry. He feels that since most electric vehicles and consumer electronics use lithium-ion batteries, the specifications of the battery are immaterial. “That’s the beauty of this kind of charging technique,” Ding said. “It doesn’t rely on who the producer is or the size of the battery.” Since the charger first diagnoses the state of the battery before responding, Dr. Ding said the manufacturing details of each gadget are not required. Moura is skeptical about the fast charging technique’s effect on battery life. When high levels of current are applied, the internal resistance of the battery causes temperature rise and damage to the battery itself. Moura explains that since the electrodes in the battery are like a sponge soaking up lithium ions, sending high pulses of current repeatedly would cause repetitive expansion and contraction of the electrode, ultimately resulting in electrode fractures and battery failure. Potential Difference has not yet conducted cyclical testing on the device and does not yet have data on how many cycles of charging an average battery can withstand. 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.
© 2015 Phys.org Explore further Journal information: Proceedings of the National Academy of Sciences Citation: Apollo-era lunar seismic data yields new lunar core model (2015, March 25) retrieved 18 August 2019 from https://phys.org/news/2015-03-apollo-era-lunar-seismic-yields-core.html According to these measurements, the compressional sound velocity of FCC-phase iron is about 400 m/s lower than that of BCC-phase iron at the same density. The most significant finding from these results is that the Vp value proposed for the lunar core based on the Apollo seismic diagrams is significantly below the value for FCC iron.The researchers further studied the possibility of iron alloyed with nickel and other elements; its incorporation at 22 atomic percent increased density at the same pressure but did not change the compressional sound velocity of the material. Thus, the researchers conclude that the sound velocity proposed for the inner core is incompatible with a core of pure solid iron or any plausible iron alloys.The researchers propose that the current most plausible structure of the moon’s core comprises a pure iron solid inner core with a liquid iron/iron-sulphur outer core. “The temperatures characteristic of the moon’s interior point to the Fe-FeS system as the most probable explanation for a liquid iron alloy stable at the thermodynamic conditions of the moon’s core. To have a solid inner core, pure Fe has to be the solid phase coexisting with Fe-FeS melt at the liquidus,” they write.Pointing out that the temperature of the core provides further constraints, the researchers observe that the presence of partial melting at the bottom of the mantle means that temperatures at the core-mantle boundary must be 1,650° K. Furthermore, for the iron inner core to be at equilibrium with the outer liquidus, the sulphur content has to be below 37 atomic percent. These results are also consistent with an extinct lunar dynamo.Taking the mineral physical constraints into consideration, they provide an estimate of the sizes of the inner and outer lunar cores. From the data, the researchers obtain an inner core with a radius of ~245 to 250 kilometers and an outer core of ~85 to 80 kilometers in thickness. The results can also be extrapolated to the conditions of telluric planetary cores of Mars size which may one day be compared to actual seismic data from Mars, and the researchers note the applicability of their conclusions to other small telluric bodies. Is iron rain the reason why Earth and the moon are so different? This is a composite image of the lunar nearside taken by the Lunar Reconnaissance Orbiter in June 2009, note the presence of dark areas of maria on this side of the moon. Credit: NASA (Phys.org)—Like the solar system’s telluric planets, including Earth itself, the moon’s internal structure is composed of geoochemically distinct mantle, crust and core layers. The core is mostly iron; much of our understanding of its composition is derived from seismic data provided by the Apollo Lunar Surface Experiments Package. More information: “Toward a mineral physics reference model for the Moon’s core.” PNAS 2015 ; published ahead of print March 16, 2015, DOI: 10.1073/pnas.1417490112AbstractThe physical properties of iron (Fe) at high pressure and high temperature are crucial for understanding the chemical composition, evolution, and dynamics of planetary interiors. Indeed, the inner structures of the telluric planets all share a similar layered nature: a central metallic core composed mostly of iron, surrounded by a silicate mantle, and a thin, chemically differentiated crust. To date, most studies of iron have focused on the hexagonal closed packed (hcp, or ε) phase, as ε-Fe is likely stable across the pressure and temperature conditions of Earth’s core. However, at the more moderate pressures characteristic of the cores of smaller planetary bodies, such as the Moon, Mercury, or Mars, iron takes on a face-centered cubic (fcc, or γ) structure. Here we present compressional and shear wave sound velocity and density measurements of γ-Fe at high pressures and high temperatures, which are needed to develop accurate seismic models of planetary interiors. Our results indicate that the seismic velocities proposed for the Moon’s inner core by a recent reanalysis of Apollo seismic data are well below those of γ-Fe. Our dataset thus provides strong constraints to seismic models of the lunar core and cores of small telluric planets. This allows us to propose a direct compositional and velocity model for the Moon’s core. At the massive pressures of Earth’s core, iron exists in a hexagonal closed packed phase (HCP), as the pressures are likely to be stable across temperature and pressure conditions. However, in less massive bodies such as the moon, Mercury and Mars, researchers believe that iron exhibits a face-centered cubic crystalline structure (FCC). However, a new analysis of the Apollo seismic data by a collaborative of researchers reveals that the seismic velocities suggested for the moon’s inner core are well below that of FCC-phase iron. They developed a dataset that provides strong constraints to existing seismic models of the moon and of small telluric planets allowing a direct compositional and velocity model of the moon’s core. They have published their results in the Proceedings of the National Academy of Sciences. Similar structures, varying conditionsThat the solar system’s planetary bodies have similar compositions is unsurprising; however, differences in the bulk masses of planets and planetary satellites imply different pressure (P) and temperature (T) conditions at their cores. These variables produce liquid versus solid core differences as well as the varying crystalline structures of solid-phase cores. Although the Earth and the moon are the only bodies for which real seismic data exists, scientists believe that the lower T and P levels of bodies such as Mercury and Mars result in solid, mostly FCC-phase iron cores. The Apollo program returned core-reflection seismic data from the moon indicating the existence of a liquid outer core and a solid inner core. A determination of the precise structure and chemical composition of the moon’s core is essential for the constraint of lunar origin models, including the possibility that the moon once had an active dynamo. Reanalyzing the dataTo explore the Apollo data and set new constraints on its interpretation, the researchers carried out density and sound velocity measurements on body-centered cubic (BCC) and FCC iron at high pressure and temperature using X-ray scattering combined with X-ray diffraction measurements. This technique is useful for measurements on metallic samples compressed in a diamond anvil cell and, recently, for measurements under high P-T conditions. 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.
More information: Yasuhiro Yamada, et al. “Exciton Lifetime Paradoxically Enhanced by Dissipation and Decoherence: Toward Efficient Energy Conversion of a Solar Cell.” Physical Review Letters. DOI: 10.1103/PhysRevLett.115.197701 Explore further The scientists, Yasuhiro Yamada, Youhei Yamaji, and Masatoshi Imada at The University of Tokyo (Yamada is currently at Osaka University), have published a paper on the counterintuitive exciton lifetime enhancement in a recent issue of Physical Review Letters.”The principle of better efficiency by energy dissipation and decoherence has already been inferred by the photosynthesis process at the chloroplasts,” authors told Phys.org. “However, it has remained as speculation until now.”As the researchers explain, understanding this enhancement requires a microscopic understanding of that way that energy is converted from sunlight into electricity—or, in terms of particles, from photons into excitons, the latter of which are bound states of an electron and an electron hole.In this energy conversion process, there is usually a tradeoff when it comes to the photon absorption rate of the photovoltaic material. A high absorption rate is beneficial for the first step when excitons are generated from incoming photons, but harmful in a later step when the electrons and electron holes must be separated at different electrodes. Unfortunately, before this charge separation can occur, the high absorption rate causes more of the excitons to quickly recombine back into photons, which are emitted back into the environment.In the new study, the scientists showed that there is a way to reap the benefits of a high absorption rate without paying the price later on because exciton recombination can be suppressed by—quite surprisingly—dissipation and decoherence. Normally, these two effects are considered harmful to photovoltaic efficiency: energy dissipation means that some energy is lost to the environment; and due to decoherence, the quantum coherence between photons and excitons that helps promote exciton generation loses its quantumness and becomes classical. Despite these drawbacks, the researchers here showed that a certain amount of dissipation, combined with an optimal coexistence of coherence and decoherence, can increase the exciton lifetime so that it has enough time to separate into an electron and hole before recombination occurs. Citation: ‘Harmful’ effects paradoxically enhance solar cell efficiency (2015, November 12) retrieved 18 August 2019 from https://phys.org/news/2015-11-effects-paradoxically-solar-cell-efficiency.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. © 2015 Phys.org Entanglement at heart of ‘2-for-1’ fission in next-generation solar cells Journal information: Physical Review Letters (Phys.org)—Dissipation and decoherence are typically considered harmful to solar cell efficiency, but in a new paper scientists have shown that these effects paradoxically make the exciton lifetime in semiconducting carbon nanotubes 50 times longer than before, which leads to a higher overall efficiency. The results provide new guidelines for exploring new photovoltaic materials that may offer unexpectedly high efficiencies. “Normally, the separation process takes much longer time than the recombination process,” authors explained. “Therefore, we need to elongate the exciton lifetime to wait until the separation process works.”To do this, the mechanism transforms short-lived “bright excitons” into longer-lived “dark excitons,” which live long enough to be separated into an electron and a hole without succumbing to recombination. Key to this transformation is that dissipation and decoherence impose a desirable quantum-to-classical transformation that makes this process irreversible: a dark exciton cannot be transformed back into a bright exciton. As the researchers explained, figuring this out was not easy to do.”The quantum-to-classical crossover process accompanied by dissipation is at the heart of difficult non-equilibrium many-body problems, and solving it requires developing an efficient computational tool with a new theoretical formulation,” authors said. “After solving the formulated quantum master equation, the principle of optimizing the decoherence and dissipation for the better efficiency has been established in the present work. It overturned the common sense notion that better efficiency should be pursued in materials with better ‘quantum yield’ that have a higher photoluminescence rate. It provides us with new guidelines.”As the scientists explained, part of the reason why the recombination suppression benefit of dissipation and decoherence has gone unnoticed until now is that the mechanism paradoxically causes a decrease in the photoluminescence, or light emission, so that a material with these effects would at first glance appear unpromising as a photovoltaic device. However, the decrease in photoluminescence is a result of the fact that the mechanism converts bright excitons (which emit light) into dark excitons (which do not). So even though more dark excitons make the material appear dark, they are what enable the material to convert light into electricity with a high efficiency.”In the next step, we urgently need to clarify how the separation of the exciton into an electron and a hole occurs with the transport of them to the opposite electrodes to generate an electromotive force, provided that their recombination to a photon is suppressed in the present mechanism,” authors said. “This requires a much longer and complex time evolution process. Another direction of research is of course to design a solar cell with better efficiency by utilizing the present principles and guidelines. This may be done for new candidates of materials.” A model of energy conversion in a semiconducting carbon nanotube, showing that bright excitons are transformed into dark excitons, which have longer lifetimes and so can undergo charge separation without recombining back into photons. Credit: Yamada, et al. ©2015 American Physical Society
Journal information: Biology Letters (Phys.org)—A pair of researchers with the University of Massachusetts has found that cane toads utilize sensory feedback to coordinate asymmetrical landings mid hop. In their paper published in the journal Biology Letters, Suzanne Cox and Gary Gillis describe a series of experiments they carried out with cane toads and what they found out by doing so. Citation: Biologists discover cane toads have a heightened sense of balance to aid in landing (2016, June 1) retrieved 18 August 2019 from https://phys.org/news/2016-06-biologists-cane-toads-heightened-aid.html More information: Sensory feedback and coordinating asymmetrical landing in toads, Biology Letters, rsbl.royalsocietypublishing.or … .1098/rsbl.2016.0196AbstractCoordinated landing requires anticipating the timing and magnitude of impact, which in turn requires sensory input. To better understand how cane toads, well known for coordinated landing, prioritize visual versus vestibular feedback during hopping, we recorded forelimb joint angle patterns and electromyographic data from five animals hopping under two conditions that were designed to force animals to land with one forelimb well before the other. In one condition, landing asymmetry was due to mid-air rolling, created by an unstable takeoff surface. In this condition, visual, vestibular and proprioceptive information could be used to predict asymmetric landing. In the other, animals took off normally, but landed asymmetrically because of a sloped landing surface. In this condition, sensory feedback provided conflicting information, and only visual feedback could appropriately predict the asymmetrical landing. During the roll treatment, when all sensory feedback could be used to predict an asymmetrical landing, pre-landing forelimb muscle activity and movement began earlier in the limb that landed first. However, no such asymmetries in forelimb preparation were apparent during hops onto sloped landings when only visual information could be used to predict landing asymmetry. These data suggest that toads prioritize vestibular or proprioceptive information over visual feedback to coordinate landing. Common Indian Toad. Bufo melanostictus. Credit: L. Shyamal/Wikipedia © 2016 Phys.org Explore further Australian giant monitor lizards trained to avoid eating toxic toads Cane toads have made the news in recent years due to their ability to easily move into new territory and take over—they eat a wide variety of plants and animals making it easy to migrate, and causing them to be considered an invasive species in places like Australia. But, it seems they also have interesting hopping abilities. To learn more about how cane toads manage to have near perfect landings when they hop, the researchers obtained several specimens and brought them into the lab for testing.To get a true sense of how a toad responds while in the air to its circumstances, the researchers applied electromyography sensors to different parts of their bodies—such sensors allow for tracking muscle usage. The researchers set up several scenarios for the toads to see how their bodies responded to different conditions. Under “normal” conditions, they noted that the toads held their front arms and feet out in a typical landing position. But, when the toads were forced to hop off a weighted glass cylinder, the cylinder rolled, which caused the toad to have to twist as a reaction, the researchers found that the toads actually rotated in the air by moving one forelimb forward before the other—an adjustment that led to them being properly aligned as they met the ground. In another experiment, they forced the toads to land on an object with a 45 degree slopped surface and were surprised to note that the toads made no adjustments at all. This, the researchers suggest, likely means the toads are not relying on vision at all when figuring out how to move their bodies in preparation for landing. Instead, it appears they rely exclusively on their vestibular system, which involves an organ in the inner ear that in humans and some other animals, has been shown to be heavily involved in maintaining balance. 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: Two studies offer evidence suggesting salmonella may have killed off the Aztecs (2017, February 22) retrieved 18 August 2019 from https://phys.org/news/2017-02-evidence-salmonella-aztecs.html More information: Salmonella enterica genomes recovered from victims of a major 16th century epidemic in Mexico, doi.org/10.1101/106740AbstractIndigenous populations of the Americas experienced high mortality rates during the early contact period as a result of infectious diseases, many of which were introduced by Europeans. Most of the pathogenic agents that caused these outbreaks remain unknown. Using a metagenomic tool called MALT to search for traces of ancient pathogen DNA, we were able to identify Salmonella enterica in individuals buried in an early contact era epidemic cemetery at Teposcolula-Yucundaa, Oaxaca in southern Mexico. This cemetery is linked to the 1545-1550 CE epidemic locally known as ‘cocoliztli’, the cause of which has been debated for over a century. Here we present two reconstructed ancient genomes for Salmonella enterica subsp. enterica serovar Paratyphi C, a bacterial cause of enteric fever. We propose that S. Paratyphi C contributed to the population decline during the 1545 cocoliztli outbreak in Mexico.Millennia of genomic stability within the invasive Para C Lineage of Salmonella enterica, doi.org/10.1101/105759AbstractSalmonella enterica serovar Paratyphi C is the causative agent of enteric (paratyphoid) fever. While today a potentially lethal infection of humans that occurs in Africa and Asia, early 20th century observations in Eastern Europe suggest it may once have had a wider-ranging impact on human societies. We recovered a draft Paratyphi C genome from the 800-year-old skeleton of a young woman in Trondheim, Norway, who likely died of enteric fever. Analysis of this genome against a new, significantly expanded database of related modern genomes demonstrated that Paratyphi C is descended from the ancestors of swine pathogens, serovars Choleraesuis and Typhisuis, together forming the Para C Lineage. Our results indicate that Paratyphi C has been a pathogen of humans for at least 1,000 years, and may have evolved after zoonotic transfer from swine during the Neolithic period. 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. Explore further White ibis salmonella shedding increases with urbanization, new study finds Salmonella forms a biofilm. Credit: CDC Spanish explorers arrived in the New World in what is now Mexico in 1519—it is believed that the native population of Aztecs at that time was approximately 25 million. A hundred years later, that number had dropped to just 1 million. Prior research has suggested that the population decline came about mostly due to diseases carried by explorers from Europe, but to date, no disease has been fingered as the culprit. In this new effort, both teams of researchers suggest it might have been a unique strain of salmonella called Salmonella enterica, also known as Paratyphi C. It has been likened to typhus, and in modern times, kills approximately 10 to 15 percent of those infected.In the first study, the team sequenced DNA from the teeth of Aztecs people that had died during a time called the cocoliztli—a great pestilence that ran from 1545 to 1576, killing off approximately 80 percent of the population. Of the 29 samples collected, 24 were linked to the cocoliztli. The researchers report that they found S. enterica in several of the samples. More details are forthcoming, the team notes, when their paper is published.In the second study, the researchers were studying the remains of a woman that had died approximately 900 years ago (300 years before the cocoliztli) in Norway, and they also found evidence of S. enterica, which suggested that the salmonella strain found in the New World victims may have come from Europe, though it is still not clear how closely they match. Again, more information will come when the paper is published.Neither paper proves conclusively that salmonella was the disease that wiped out most of the Aztecs, but the new evidence does suggest it likely played a part. © 2017 Phys.org (Phys.org)—Two separate studies conducted by two teams of researchers has led to evidence suggesting that salmonella infections may have been one of the factors that led to the deaths of the vast majority of the Aztecs living in Mexico after the arrival of the Spaniards. Both studies were conducted by teams with members from around the globe and both resulted in papers that have been uploaded to the bioRxiv preprint server as they await review prior to formal publication.