first_img Spacecraft Could Save Earth from Asteroids Citation: Scientist says nuclear weapons may be best bet for saving Earth from asteroids (2010, June 28) retrieved 18 August 2019 from https://phys.org/news/2010-06-scientist-nuclear-weapons-earth-asteroids.html According to Dearborn, the sheer power of a nuclear explosion may make it the most practical and cost-effective option for deflecting or fragmenting asteroids, compared with alternatives such as chemical fuel or laser beams. For one thing, a nuclear explosive would be cheaper to launch into space due to its large amount of energy per unit mass. In contrast, a non-nuclear blast might require several launches for an equivalent amount of power.Also, the nuclear option could be implemented in a short amount of time; a detonation just 15 days before impact could fragment or divert the course of a 270-meter asteroid (the size of Apophis, which has a 1 in 250,000 chance of striking Earth in 2036) to avoid a collision. On the other hand, a laser such as one at the National Ignition Facility at Lawrence Livermore would take 6,000 years to sufficiently divert the course of the same size asteroid. As far as the radiation released from a nuclear explosion in space, Dearborn said that you wouldn’t even be able to measure the difference on Earth. The explosion would occur millions of miles out in space, where there is already an intense radiation environment.Dearborn has developed models and run simulations to determine the effects of a nuclear detonation occurring both near and on the surface of an asteroid. His simulations show that the best strategy depends on both the size of the asteroid as well as how much time we have before impact. If a collision with a smaller asteroid is a few decades away, detonating a nuclear explosive near the asteroid could nudge it off course while still keeping it intact. But if a collision with a large asteroid is just weeks away, a direct detonation on the asteroid would be required, although some smaller fragments could still strike Earth. While the size of the asteroid and its distance from Earth can be estimated quite well, the biggest unknown variable in any defense strategy is the asteroid composition. Asteroids are a diverse class of objects, and some materials fragment more easily than others. Dearborn advised that, if we had 30 years to avoid a collision, the best thing to do would be to launch a characterization mission to the asteroid. Even if Dearborn and other scientists would like to test a nuclear explosive in space, test ban treaties as well as political and public opposition make a test unlikely.Fortunately, scientists aren’t expecting an asteroid impact any time soon. NASA has identified and categorized about 90% of near-Earth objects that are large enough (more than 10 km [6.2 miles] in size) to cause mass extinction on Earth, and none of these pose a significant risk of collision in the near future – even Apophis is considered to have very low risk. Smaller objects, on the other hand, are more difficult to track down. The smallest known asteroid, 1991 BA, measures 6 meters (20 feet) across.”In a few more years, we’ll be able to say that there’s nothing out there to cause a global catastrophe,” said David Morrison, director of the NASA Lunar Science Institute and senior scientist for Astrobiology at NASA’s Ames Research Center. “But, there’ll be a million that will be big enough to wipe out an entire city. It’ll take a long time, if ever, to find them and figure out their orbits. The bottom line is, we could be hit by one of those small ones at any time, with no warning at all. Right now, I can say almost nothing about the probability of one of those small objects hitting us, because we simply haven’t found all of them.” (PhysOrg.com) — If scientists detect an asteroid headed directly for Earth – one that was large enough to pose a serious threat to life on our planet – would it be wise to bring out nuclear weapons to prevent an impact? Over the past several years, scientists have expressed conflicting opinions on the use of nuclear weapons as a defense against asteroids. Part of the problem is that it’s very difficult to know what asteroids are made of, and how they will respond to different types of nuclear explosives. But at the semiannual meeting of the American Astronomical Society held last month, physicist David Dearborn of the Lawrence Livermore National Laboratory argued that nuclear weapons could be the best strategy for avoiding an asteroid impact – especially for large asteroids and little warning time. 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: via: Space.com and Scientific American © 2010 PhysOrg.com Illustration of an asteroid impact. Credit: NASA. Explore furtherlast_img read more

first_img The study, led by Alessandro Acquisti from Carnegie Mellon University, combined the use of three different technologies – cloud computing, facial recognition and public information that can be found on various social networking sites.They used these technologies in three different experiments. In the first experiment, Acquisti and his team were able to identify members of an online dating site where members do not use their real names for identification. The second experiment allowed the research team to identify college students in real life walking on campus based solely on their face and information gathered online.In the third experiment, the researchers used the technology to predict personal interests and identify students, including some social security numbers, with only a photo of their face to start. Social security numbers, Acquisti pointed out in 2009, are a security flaw as they can be predicted if you know the person’s hometown and date of birth. This new technology uses that information and in many cases can determine a person’s social security number. In this experiment, the researchers looked at Carnegie Mellon University students and those who had a date of birth and hometown displayed on their social media account page. They developed a smartphone application which gathers both online and offline information and displays it over the person’s facial image on the phone.Acquisti says that while all attention has been turned to providing security in cyberspace, this new technology allows one to step outside of cyberspace and into the real world. Using cyberspace as a means to identify someone living down the street or who you pass by every day on your way to work is a possibility. The idea of protecting your privacy has been changed and caution should be used before you share the next picture of yourself.Facebook has recently limited the facial recognition photo-tagging on its site to people in your friends list and Google has not yet allowed facial recognition technology into its searches. Social security numbers can be predicted with public information, researchers find Explore further Citation: Facial recognition software could reveal your social security number (2011, August 2) retrieved 18 August 2019 from https://phys.org/news/2011-08-facial-recognition-software-reveal-social.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.center_img More information: “Identifying indicators of illegal behaviour: carnivore killing in human-managed landscapes,” Proc. R. Soc. B July 27, 2011. doi: 10.1098/rspb.2011.1228 © 2010 PhysOrg.com According to a new study which will be presented August 4 at the Black Hat security conference in Las Vegas, technology has made it possible to identify and gain the personal information of strangers by using facial recognition and social media profiles like Facebook.last_img read more

first_img(Phys.org)—Belgium is to build an artificial island made of sand three km off the Belgian coast. This will be a doughnut-shaped structure designed to store wind energy once the plan gets a final go-ahead. This North Sea island would work as an offshore substation; it would take five years or more to build. The plan was announced earlier this week in a presentation at the port of Zeebrugge by Johan Vande Lanotte, Belgium’s North Sea minister. 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. Experts okay restart of worrisome Belgian nuclear plants More information: www.reuters.com/article/2013/0 … dUSL6N0AM7GU20130117phys.org/news/2013-01-experts- … belgian-nuclear.html Explore furtherlast_img read more

first_img Journal information: Biology Letters More information: Spontaneous male death and monogyny in the dark fishing spider, Biology Letters, Published 19 June 2013 doi: 10.1098/rsbl.2013.0113AbstractMonogyny (male monogamy) is found in a diverse assemblage of taxa, and recent theoretical work reveals that a male-biased sex ratio can favour the evolution of this relatively rare mating system. We integrate this theoretical framework with field observations and laboratory experiments involving the sexually size dimorphic fishing spider, Dolomedes tenebrosus, to test the prediction that this species exhibits monogyny. Field surveys revealed a male-biased sex ratio, likely resulting from different life-history strategies (early male maturation). Results from mating trials supported our prediction of monogyny as we discovered that males mate with a single female. Unexpectedly, however, we observed that mating results in obligate male death and genital mutilation. Additional field observations of released individuals suggest that males are not limited by their ability to encounter additional females. Controlled laboratory assays demonstrated that males discriminate among virgin and non-virgin female silk cues, consistent with predictions of first-male sperm precedence. In summary, we report a novel case of male self-sacrifice in a species that exhibits female-biased sexual size dimorphism, male-biased sex ratio, genital mutilation and a suggestion of first-male sperm precedence; all of which are consistent with theoretical predictions of the evolution of monogyny. 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 Reversal of the black widow myth (Phys.org) —Behavioral biologists at the University of Nebraska have found that male dark fishing spiders become immobile immediately after mating and die a short time later. In their paper published in the journal Biology Letters, the team describes the mating behavior of the spiders and notes that the male dies spontaneously without assistance from the female.center_img © 2013 Phys.org Postcopulation the male hangs from the female’s genital opening by the single pedipalp (circled) that he inserted during copulation. (Online version in colour.) Credit: Biology Letters, Published 19 June 2013 doi: 10.1098/rsbl.2013.0113 As with many other spiders, the male dark fishing spider is much smaller than the female counterpart. Unlike other species however, the death of the male after mating isn’t due to the female killing him. Instead it appears his death is due to a form of genital mutilation.Field observations near the University by the research team revealed that when the male approaches the female (with a preference for virgins) he mounts her, rocks her body and ejaculates sperm onto a sperm-web. That sperm is then pulled into dual pedipalps (appendages on the front end of its body) which fill with fluid causing them to inflate. The male spider then inserts one of the engorged pedipalps into the female genital opening and deposits the sperm. Once that’s done, the male’s legs curl under him and he becomes immobile and if not eaten by the female dies within a couple of hours. For the male, because he only ever gets a chance to mate once, this is a form of monogamy called monogyny (because it’s strictly one sided).Closer observation of male spiders after copulation showed that the pedipalps remained inflated after mating, an unusual occurrence for spiders. The researchers speculate it’s likely the reason the spider dies after mating. In the lab they found that accidently causing the pedipalps to inflate in a few specimens led to the same result—the spiders curled up, became immobile and died after a couple of hours. In testing the males after copulation they found them to be completely unresponsive to touching poking or prodding. They also note that because the females generally eat the male afterwards, becoming sated in the process, there is a strong chance that the sperm from the male will result in offspring. Thus, the males’ mating ritual appears to convey a reproductive advantage. Citation: Male dark fishing spiders found to die spontaneously after mating (2013, June 20) retrieved 18 August 2019 from https://phys.org/news/2013-06-male-dark-fishing-spiders-die.htmllast_img read more

first_img Explore further Citation: Mathematical model tackles ‘Game of Thrones’ predictions (2014, September 30) retrieved 18 August 2019 from https://phys.org/news/2014-09-mathematical-tackles-game-thrones.html Take events from the past, build a statistical model, and tell the future. Why not apply the formula to novels? Can contents in future books be predicted based only on data from existing ones? Richard Vale at the University of Canterbury in New Zealand, said The Physics arXiv Blog, has taken on the challenge in predicting content of as yet unpublished novels in the “A Song of Ice and Fire” series by George R R Martin. The novels are the basis of the television series, “Game of Thrones.” The series has five books and two more are awaited. Before proceeding, it should be emphasized that the paper comes with a spoiler alert, so avoid linking to Vale’s study if you have not read the first five books. As The Physics arXiv Blog explained, “Each chapter in the existing books is told from the point of view of one of the characters. So far, 24 characters have starred in this way. The approach that Vale has taken is to use the distribution of characters in chapters in the first five books to predict the distribution in the forthcoming novels.”After creating a model, Vale runs a computer program to find the parameters in the model that best fit the data. He uses the model to find the probability distributions of the number of chapters that each character will star in, in book 6 and book 7. What kinds of predictions result? They include predictions about certain characters unlikely to star in any chapters and if one particular character is likely to be dead. Vale’s paper submitted to arXiv is “Bayesian Prediction for The Winds of Winter.” As Vale described it, “Predictions are made for the number of chapters told from the point of view of each character in the next two novels in George R. R. Martin’s emph{A Song of Ice and Fire} series by fitting a random effects model to a matrix of point-of-view chapters in the earlier novels using Bayesian methods.” There is also a “Spoiler Warning” that readers who have not read all five existing novels in the series should not read further “as major plot points will be spoiled.”The blog commented on how this is a “fascinating exercise in statistical modeling that will do more to introduce the process to a wider range of people than any number of textbooks or Wikipedia entries.”Vale is a Lecturer in the Statistics Department at the University of Canterbury. He has a PhD in mathematics from the University of Glasgow and was an HC Wang Assistant Professor at Cornell University. Vale acknowledged several shortcomings in his model— such as not dealing with the possibility of new characters being introduced and a model resting on a relatively small amount of data. Robin Kawakami of The Wall Street Journal, writing in the Speakeasy blog, quoted Vale saying “Game of Thrones” cannot be predicted using statistics alone. He said his project can be viewed as “fun data analysis.” He said in an e-mail to Speakeasy, just as many people make fan art by drawing favorite characters from books, “As a mathematician/statistician, this mathematical model is my version of fan art.” Posterior predictive distributions for the number of POV chapters for nine characters in The Winds of Winter. Credit: arXiv:1409.5830 [stat.AP] © 2014 Phys.org More information: Bayesian Prediction for The Winds of Winter, arXiv:1409.5830 [stat.AP] https://sp2.img.hsyaolu.com.cn/wp-shlf1314/2020/IMG701.jpg” alt=”last_img” /> read more

first_imgThe found abundance pattern in 68 Tauri: circles (Adelman and al.), dots (this work). Credit: Martinet et al., 2017. Located some 150 light years from the Earth, 68 Tauri is a binary star in the Hyades open cluster. With an effective temperature of 9,025 K and a mass of nearly 2.3 solar masses, it is the hottest and most massive member of this cluster.68 Tauri was initially classified as main-sequence star of spectral type A. However, subsequent observations have shown that it is a chemically peculiar metallic-line star (Am star) due to its distinct underabundance of scandium and overabundances of the iron-peak and heavy elements.Given that the last abundance analysis of 68 Tauri was performed in 2003, Sebastien Martinet of the Grenoble Alps University and Richard Monier of the Paris Observatory decided to conduct a new study with the aim of learning more about the composition of this star. The researchers used updated atomic data hoping to redetermine and expand the star’s chemical composition.”We have modeled the high resolution SOPHIE (R=75000) spectrum of 68 Tauri using updated model atmosphere and spectrum synthesis to derive chemical abundances in its atmosphere. In particular, we have studied the effect of the inclusion of the hyperfine structure of various barium isotopes on the determination of the baryum abundance in 68 Tauri. We have also derived new abundances using updated accurate atomic parameters retrieved from the NIST database,” the paper reads.The new analysis allowed the scientists to determine abundances of 68 Tauri more accurately, improving our understanding of chemical composition of this star.For instance, the team found that 68 Tauri exhibits underabundance of scandium and slight underabundances in carbon, oxygen, magnesium, silicon and calcium, mild overabundances of the iron-peak elements and large overabundances of the rare-earth elements.Furthermore, as a result of including hyperfine structure of various isotopes of Barium, they found that the abundance of this element is significantly lower when compared to the study published in 2003. According to the study, this highlights the importance of hyperfine structure in such analyses.”We find a large difference on the barium abundance when including the full hyperfine structure. (…) We stress the importance of taking into account the hyperfine structure for all isotopes when available in order to derive accurate abundances,” the researchers wrote in the paper.When it comes to abundances of other elements, the new study shows that they are consistent with the values presented in the previous study, except for scandium. The authors noted that the newly determined values generally differ from 0.01 dex up to 0.4 dex as a result of adopting new atomic data, confirming that 68 Tauri is a chemically peculiar Am star. Citation: Researchers conduct more accurate chemical analysis of the star 68 Tauri (2017, October 3) retrieved 18 August 2019 from https://phys.org/news/2017-10-accurate-chemical-analysis-star-tauri.html Researchers analyze chemical composition of the newly discovered star cluster Gaia 1 More information: Hyperfine Structure and Abundances of Heavy Elements in 68 Tauri (HD 27962), arXiv:1709.10068 [astro-ph.SR] arxiv.org/abs/1709.10068AbstractHD 27962, also known as 68 Tauri, is a Chemically Peculiar Am star member of the Hyades Open Cluster in the local arm of the Galaxy. We have modeled the high resolution SOPHIE (R=75000) spectrum of 68 Tauri using updated model atmosphere and spectrum synthesis to derive chemical abundances in its atmosphere. In particular, we have studied the effect of the inclusion of Hyperfine Structure of various Baryum isotopes on the determination of the Baryum abundance in 68 Tauri. We have also derived new abundances using updated accurate atomic parameters retrieved from the NIST database. 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. (Phys.org)—French astronomers have recently presented a new abundance analysis of the star 68 Tauri (also known as HD 27962), which determines its chemical composition more precisely than previous studies. The results of the research are available in a paper published Sept. 28 on the arXiv pre-print repository. © 2017 Phys.org Explore furtherlast_img read more