Explore further As originally reported in Nature, Takehiko Ogawa and his team from Yokohama University have discovered that by using the right mix of chemicals (which turned out to be the commercially available KnockOut Serum – a solution made to assist in stem cell growth) they could not only keep a mouse testes sample alive, but that it would, after just a few weeks, begin to produce viable sperm cells; sperm cells that when injected into a female ovum, wound up in the delivery by surrogate, of a live healthy mouse.Scientists have been working on the problem of producing viable sperm cells for over a hundred years, with little to no success. Until now, researchers had been able to keep testes tissue alive, but when the sperm cells reached the meiosis stage, (the point during cell division when chromosomes are swapped) things simply stopped.In the new procedure, a testes sample was taken from the testicle of a live male mouse before it was old enough to produce sperm cells. That sample was then continuously soaked in the KnockOut solution for several weeks, and then, the sample began to produce live sperm cells; complete with head, body and tails, just as they would have had they been left in their natural state. Those mice that were born as a result so far seem normal, and were even able to reproduce as well. The team also discovered the procedure would work with a previously frozen specimen as well.The reason this breakthrough is so important is because it might help infertile men, particularly those who as young boys lost their ability to reproduce due to cancer treatment, have children. It’s also important because it will help researches better understand how cells work; which might eventually lead to more breakthroughs in other areas. (PhysOrg.com) — In what can only be described as cosmic forces at work, Japanese scientists working at Yokohama University, just south of Tokyo, have in the midst of a national crises, announced a major breakthrough in fertility science; they have figured out how to grow sperm cells outside the body. While the nation counts its losses from the earthquake and tsunami, a new way to help men who have been unable to conceive children, might just be on the way. Citation: Japanese sperm cell breakthrough offers hope to infertile men (2011, March 24) retrieved 18 August 2019 from https://phys.org/news/2011-03-japanese-sperm-cell-breakthrough-infertile.html The long road of fertility © 2010 PhysOrg.com More information: In vitro production of functional sperm in cultured neonatal mouse testes, Takuya Sato, Kumiko Katagiri, Ayako Gohbara, Kimiko Inoue, Narumi Ogonuki, Atsuo Ogura, Yoshinobu Kubota & Takehiko Ogawa, Nature 471, 504–507 (24 March 2011) doi:10.1038/nature09850 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: The The Kilobot Project, via IEEE Thanks to RoboEarth the bots can learn on their own © 2010 PhysOrg.com Introduction to Kilobot Enter the Kilobots. These small and simple robots are about the size of a US quarter that moves around on a set of vibrating legs. These small robots are able to communicate with each other by blinking lights mounted on their cases. While each individual unit may not seem that advanced or impressive the real impact is what happens when the robots work as a system.Swarms of hundreds or thousands of these robots, which each cost about $14 and take roughly fine minuets to assemble, are not designed to be used on an individual basis. The first group to be used by a research group at Harvard University is starting out with a group of 25. While this may not be the stuff of the nightmare scenarios of a thousands of horror movies as of yet these robots could easily be swarmed by the 1000’s if the small scale testing goes well. Citation: Kilobots bring us one step closer to a robot swarm (2011, June 17) retrieved 18 August 2019 from https://phys.org/news/2011-06-kilobots-closer-robot-swarm.html Demonstrations of Kilobot collective behaivors on up to 29 robots The use of the robots does vary depends on how they are programmed. The robots can, for now, only understand simple tasks but with the help of the intelligence of the hive mind the swarm can be surprisingly responsive to the changing environment. Explore further Demonstrations using a small number of Kilobots (PhysOrg.com) — When you think about robots, the odds are that you think about something that is fairly large. Maybe you picture a robot arms bolted to the floor of a factory or if you are feeling particularly dramatic maybe you even pictured the terminator. You probably do not think much about tiny robots, but they have some big potential as a robot swarm. 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: May the force be with us? Precise measurements test quantum electrodynamics, constrain possible fifth fundamental force (2013, June 4) retrieved 18 August 2019 from https://phys.org/news/2013-06-precise-quantum-electrodynamics-constrain-fundamental.html (Phys.org) —Quantum electrodynamics (QED) – the relativistic quantum field theory of electrodynamics – describes how light and matter interact – achieves full agreement between quantum mechanics and special relativity. (QED can also be described as a perturbation theory of the electromagnetic quantum vacuum.) QED solves the problem of infinities associated with charged pointlike particles and, perhaps more importantly, includes the effects of spontaneous particle-antiparticle generation from the vacuum. Recently, scientists at VU University, The Netherlands, published two papers in quick succession that, respectively, tested QED to extreme precision by comparing values for the electromagnetic coupling constant1, and applied these measurements to obtain accurate results from frequency measurements on neutral hydrogen molecules that can be interpreted in terms of constraints on possible fifth-force interactions beyond the Standard Model of physics2. In addition, the researchers point out that while the Standard Model explains physical phenomena observed at the microscopic scale, so-called dark matter and dark energy at the cosmological scale are considered as unsolved problems that hints at physics beyond the Standard Model. A schematic layout of the experimental setup. The oscillator cavity is seeded by a cw Ti:Sa laser, the pulsed output of which makes multiple passes in an amplifier stage. The amplified output is frequency up-converted in two frequency doubling stages leading to fourth harmonic generation of ~211 nm. The deep UV radiation is sent to the experiment, where molecules in the X1 Σg+ ν´ = 1 state, populated by electrical discharge, are optically excited in a two-photon Doppler-free configuration . The cw-seed light is compared to a frequency comb while the frequency offset between pulsed and cw-seed light is measured via on-line chirp analysis to obtain an absolute frequency calibration. See text for further details. SHG: second harmonic generation; PMT: photomultiplier tube; and YAG: yttrium-aluminum garnet. Reproduced with permission from G. D. Dickenson et al, Phys. Rev. Lett. 110, 193601 (2013) (a) Recording of the EF1 Σg+ – X1 Σg+ (0, 1) Q(0) two photon transition in H2 (experimental data). Below the residuals from a fit to a Gaussian profile (smooth theoretical curve, plotted in red) are shown. (b) Partial level scheme of molecular hydrogen showing the measurement principle to obtain the ground tone vibrational splitting as a combination difference. The transitions measured in the present study are indicated by solid arrows while those measured in a separate study are shown as dashed arrows. (c) Assessment of the ac Stark effect in a plot of the absolute frequency of the EF – X(0, 1) Q(0) transition in H2 vs the 211 nm power density in the interaction zone. The open circle signifies the result shown in (a). Reproduced with permission from G. D. Dickenson et al, Phys. Rev. Lett. 110, 193601 (2013) Ubachs adds that the HD+ molecular ion is a good testing ground for QED as well, since its single electron simplifies the calculation. Moreover, he notes that since collisions have a disturbing effect on the molecules and perturb the level structure, they performed the measurements in a collisionless molecular beam to determine the fundamental ground tone vibration of H2, HD, and D2. They also derived rotationless vibrational splitting from the combination difference between electronic excitation More information: 1Fundamental Vibration of Molecular Hydrogen, Physical Review Letters 110, 193601 (2013), doi:10.1103/PhysRevLett.110.193601 2Bounds on fifth forces from precision measurements on molecules, arXiv.org, submitted 24 Apr 2013, arXiv:1304.6560v1Related 3New Determination of the Fine Structure Constant and Test of the Quantum Electrodynamics, Physical Review Letters 106, 080801 (2011), doi:10.1103/PhysRevLett.106.080801 4Deep-Ultraviolet Quantum Interference Metrology with Ultrashort Laser Pulses, Science 21 January 2005: Vol. 307 no. 5708 pp. 400-403, doi:10.1126/science.1106612 (a) Current and previously measured values for the fundamental ground tone vibration in H2. The dashed horizontal line represents the value [and the shaded (yellow) area represents ±1σ uncertainties] from the full ab initio calculations including QED effects. (b), (c) represent measured values for the ground tone of HD and D2, respectively, along with the full ab initio calculations. These are compared with the results of Rich et al. and McKellar and Oka for HD and D2, respectively. Reproduced with permission from G. D. Dickenson et al, Phys. Rev. Lett. 110, 193601 (2013) Journal information: Physical Review Letters , Science In addition to the Ti:Sa laser, Ubachs points out that two other techniques that the scientists used to address these challenges:an additional laser system known as a frequency comb laser for the calibration of frequenciesthe breakthrough in quantum chemistry computational techniques by his colleagues in PolandRegarding recent disagreement on proton size between muonic hydrogen and atomic hydrogen experiments, when asked if the high level of agreement between the most accurate theory and experiment for the molecular hydrogen level energies may be interpreted to constrain effects of possible long-range hadron-hadron interactions, Ubachs stresses that their work “does not have an immediate impact on the proton size puzzle,” adding that the spectroscopy of the hydrogen atom and the muonic atom probes the forces between leptons (electrons and muons) and hadrons (protons). “We’re now performing a highly accurate experiment on a system that is calculable and which contains interactions between hadrons. This force is purely electromagnetic in QED, but we test if there are additional contributions that could possibly indicate a fifth force. That being said, our work shows that those are not present, up to a certain level of accuracy.”Going forward, Ubachs sees a number of possibilities for improvement, including extending the pulse length somewhat, which he acknowledges will only give an incremental improvement; probing higher vibrations than only the fundamental ground tone; and taking a drastically different route in performing direct frequency comb spectroscopy on the H2 system along the lines we explored in an atom4.Ubachs also mentions other areas of research that might benefit from their research. “Other laser spectroscopists will use our Ti:Sa laser that will be marketed by the German company,” Ubachs concludes. “We have understood that there is an interest from several scientific groups, in particular in the area of atmospheric physics.” Prof. Wim Ubachs discussed the research he and his colleagues (at University of San Carlos, Philippines; Mickiewicz University, Poland; and University of Warsaw, Poland) undertook, citing some of the challenges they faced, in a conversation with Phys.org. “The challenges in testing QED to extreme precision by comparing values for the electromagnetic coupling constant are twofold,” Ubachs says. “Using lasers, we measured transition frequencies as accurately as possible. These measurements, in turn, had to be compared with calculations, which also had to be performed at the highest accuracy levels, involving many steps: First, solving the Schrodinger equation for the H2 molecule, and secondly calculating the relativistic corrections and the terms associated with quantum electrodynamics.” The latter, he notes, involves calculating the interaction of the particles with the quantum vacuum – that is, with the spontaneously generated particles from the void. In the QED calculations, the scientists used the existing best value from CODATA – the physics data base where all previous experiments are evaluated – for the fine structure constant known as alpha. “The value of alpha,” Ubachs explains, “is itself derived from two experiments measuring the g-factor of the electron, and alternative recoil measurements on rubidium atoms3.” The first value is in principle the most accurate, he adds, bur in order to get from the g-factor to alpha, an enormously complex calculation has to be performed. Explore further © 2013 Phys.org. All rights reserved. “We performed an experiment on the purely vibrating molecules, H2, D2 and HD, because it simplifies the calculations” Ubachs adds. “Experimentally we could also include rotation of the molecule – and in fact we have performed these measurements, which will be published soon – but the calculations are even more complex, and therefore less accurate.”One other challenge also provided their biggest breakthrough – namely, performing the experiment with a long-pulse injection-seeded oscillator-amplifier titanium-sapphire, or Ti:Sa, laser system. “Yes, this is special,” says Ubachs. “We developed a special laser system for these types of measurements.” The pulses of the Ti:Sa laser are long (≥20 nanoseconds) so that the bandwidth can be narrow, which is determined by the Fourier principle dictating that short-pulsed wave phenomena give bandwidth. “On the other hand,” Ubachs continues, “the radiation must be pulsed because we need to produce the fourth harmonic of the fundamental frequency, thus converting the wavelength from 840 nm to 210 nm – something that can only be done with pulsed laser radiation. (Ubachs notes that this special laser will be produced under license by the German company Radiant Dyes.) New experiments challenge fundamental understanding of electromagnetism 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.
REGRES. (1) Suicide F plasmids are transferred to the donor strain by conjugation, and multiple F plasmid integrant Hfr strains are selected. (2) Isolated Hfr strains are mated with an F– recipient strain, permitting genome transfer and homologous recombination with the genomes of recipient cells. (3) A suitable selection or screening procedure for individual transconjugants displaying the phenotype of interest is applied. (4) Isolated strains are genotyped against a panel of known alleles. (5) Strains of interest, usually with the fewest donor alleles, are selected for whole-genome sequencing and can be used as donors for another round of REGRES, if desired. Credit: Copyright © PNAS, doi:10.1073/pnas.1314561111 Explore further Genomics analysis demonstrates natural selection at work “Our results imply that these earlier ‘potentiating’ mutations weren’t absolutely necessary for expressing the beneficial Cit+ trait, as we first thought. Instead,” Barrick points out, “they seem to make it possible for evolution to follow a tenuous path. We hypothesize that these mutations may actually be deleterious to E. coli growth without the earlier potentiating mutations rewiring bacterial metabolism in some unknown way.” This would mean that if these mutations occurred in certain strain backgrounds (like the ancestor) that they would rapidly go extinct from the population – but with the potentiating mutations present, it appears that the first mutation that affected the CitT transporter protein and gave a weak ability to use citrate was ever-so-slightly beneficial for growth and survival. , Nature Model for the evolution of citrate utilization in the E. coli long-term evolution experiment. (A) There were three major epochs in the evolution of this metabolic innovation: potentiation, actualization, and refinement. Weakly Cit+ cells were first isolated from the population after the rnk–citG actualizing mutation that amplified and activated the CitT transporter (shown as the citT allele). There was not an appreciable increase in the final cell density at the end of each growth cycle in the evolution experiment at this point (Top). After the dctA” refinement mutation, there was a substantial increase in population size because cells were able to fully use citrate, which we distinguish from the rudimentary Cit+ phenotype as the strong Cit++ phenotype (Middle). The evolution of Cit++ is statistically more likely from certain Cit– genetic backgrounds that arose later in this population, presumably because they accumulated one or more potentiating mutations relative to the ancestor (3, 10). Key mutations are shown with their approximate timings relative to these evolutionary epochs and one another (Bottom). (B) Cit++ phenotype is not the product of all-or-none epistasis with potentiating mutations. The progression of citrate utilization phenotypes as they evolved in the LTEE in strains that contained key mutations in the context of earlier evolved alleles (Upper) and qualitative phenotypes of reconstructed strains containing only key evolved alleles in the ancestral genetic background (Bottom) are shown. The evolved citT mutation alone is sufficient for detectable but extremely limited citrate utilization, as observed in early Cit+ isolates (3). The citT and dctA” mutations together are sufficient for full citrate utilization characteristic of the Cit++ phenotype, even in the absence of potentiating mutations. (C) Mechanism of Cit++ refinement. When both the CitT and DctA transporters are expressed, due to the citT and dctA” mutations, their activities can be coupled so that the proton-motive force (H+) powers reuptake of succinate or other C4-dicarboxylate substrates for continued citrate import, yielding the Cit++ phenotype. It is possible that the unknown potentiating mutations make sufficient succinate available from glucose metabolism to power limited citrate import through CitT but that this does not result in a sustainable cycle. Copyright © PNAS, doi:10.1073/pnas.1314561111 Dr. Jeffrey E. Barrick discussed the paper that he, Graduate Research Assistant Erik M. Quandt and their co-authors published in Proceedings of the National Academy of Sciences. “REGRES is a combination of tried-and-true genetic methods, known for decades, including conjugation,” Barrick tells Phys.org. (Conjugation is a form of bacterial pseudo-sex for exchanging genes or mutations, in which a portion of the chromosome of one bacterium is transferred into another.) “The new aspect in REGRES,” Barrick continues, “was creating a way for this process to be used serially – that is, to keep performing this transfer into a ‘blank’ ancestral genome, starting from a genome that had many evolved genetic changes.” This so-called backcrossing procedure sequentially removed all mutations that weren’t required for surviving the growth conditions used, which required being able to efficiently utilize citrate as a nutrient. The other technology that enabled REGRES, Barrick notes, was next-generation DNA sequencing, which allowed the scientists to fully track which mutations were removed by not being transferred at each step.In one of the study’s key findings, the researchers identified a mutation that converts a rudimentary form of the innovation into a refined trait that confers a decisive competitive advantage, by dissecting the genetics of this trait using REGRES. “We were very surprised that after starting with a collection of more than 70 mutations in the evolved Cit+ strain – most of which were related to improving growth on glucose as a carbon source – we were able to find just two mutations that conferred the ability to utilize citrate.” Barrick explains that this was unexpected due to very compelling evidence that mutations which occurred before citrate utilization arose in this population made certain E. coli in this population more likely to be able to evolve the ability to use citrate. This evidence is from studies that re-played evolution from many genetic starting points in what he describes as “very elegant” experiments by Zachary Blount and Richard Lenski at Michigan State University1,2. In addition, Barrick states that the REGRES method was key to sifting through the more than 70 evolved mutations that could have been necessary for utilizing citrate. Journal information: Proceedings of the National Academy of Sciences Citation: Unpacking the past: Identifying a key evolutionary step in E. coli metabolism (2014, January 28) retrieved 18 August 2019 from https://phys.org/news/2014-01-key-evolutionary-coli-metabolism.html (Phys.org) —Evolution is a process that takes place over long periods of time over which genetics and ecology may interact, producing novel phenotypic traits. Researchers previously found that after roughly 31,500 generations had passed in a laboratory evolution experiment a rare metabolic innovation emerged in which Escherichia coli developed the ability to metabolize citrate (Cit+) in its growth medium. Through genetic analysis with a recursive genomewide recombination and sequencing method (REGRES), scientists at University of Texas, Austin have now identified a key mutation that they say demonstrates how improvement of an emergent trait can be as important to its eventual success as earlier mutations or environmental conditions that may have been necessary for it to initially evolve. © 2014 Phys.org. All rights reserved. “Once this mutation was able to persist in the face of competition with other E. coli lineages in the population that were improving through other mutations,” Barrick adds, “it gave enough time to get the second key mutation, which affects the DctA transporter protein. This mutation completed a cycle that enabled all of the citrate in the media to be efficiently utilized by this strain.” This innovation gave the E. coli strain in question what Barrick describes as an “overwhelming” evolutionary advantage relative to its competitors that remained limited to competing for a lesser amount of the nutrient glucose.An important conclusion of the study is that refinement of an emergent trait from a rudimentary form may be crucial to its evolutionary success. “Evolutionary innovations often seem to come out of nowhere, like the huge population expansion in this laboratory E. coli population when it evolved to be able to fully exploit citrate that had always been present in the growth medium for the preceding 15 years,” Barrick tells Medical Xpress. “Our study shows that earlier mutations that may not have immediately obvious effects can be important for setting the stage for evolutionary breakthroughs. It’s this exploratory mode of evolution – where there may not be any immediately obvious effects until a whole string of complementary mutations are put together – that can surprise us when we watch evolution happen in real time.”More specifically, the study’s results imply that the DctA mutation was important for improving this rudimentary trait to enable full citrate utilization. “Once the REGRES results implied that only the DctA and CitT mutations were common to all backcrossed genomes, we were able to take the ancestral strain and add just those two mutations to it. Since this recapitulated a very strong ability to use citrate, we concluded that these were the key mutations required for the Cit+ phenotype.” Moreover, he adds, the timing of these two mutations in the original population was also coincident with the earliest known weak Cit+ utilizers (CitT mutation) and a population expansion where E. coli with the refined Cit+ trait took over the population (DctA mutation) and grew to a much higher density than was possible without using this additional nutrient source.Moving forward, Barrick says, the researchers remain very interested in identifying the potentiating mutations and/or ecological conditions that enabled the weakly Cit+ E. coli to persist in the population long enough for Cit+ refinement causing the population expansion to occur. “To solve this puzzle, we’re trying to more precisely determine the order of the more than 70 mutations in the Cit+ strain that was examined in this study.” They’re doing this, he explains, by going back into the frozen “fossil record” of this population and sequencing the genomes of more bacteria. “We hope to eventually find a context of earlier mutations that makes the actualizing CitT mutation beneficial enough to explain why it did not go extinct when it occurred.” Since the fitness effects of these mutations are much more subtle, Barrick adds, this is proving to be difficult.”In the short term,” he continues, “we’re also following up on an interesting story related to a mutation that we discovered as a side effect of performing REGRESS. We found that a new mutation appeared during our backcrossing procedure that was not present in the Cit+ strain that we started with. It turns out that similar mutations eventually appeared many times in the actual long-term E. coli evolution experiment population, so it was beneficial for further refinement of the Cit+ trait to get one of these mutations.” Interestingly, this mutation appears to reverse the effects of an earlier mutation that is present in these genomes, which appeared before citrate utilization ever arose. “We therefore have a case where becoming Cit+ changed E. coli metabolism so much that it made it beneficial to reverse the trajectory of earlier evolution. This sort of rewiring is a hallmark of evolutionary innovation.”Along with many other researchers Barrick and his co-authors continue to develop improved tools like REGRES to remix and edit the sequences of bacterial genomes. “For example,” he illustrates, “it can still be difficult to go into the lab and reconstruct complex sequence rearrangements in a genome like the one that turned on expression of the CitT transporter.”Barrick notes that other areas of research might benefit from their study. “The REGRES methodology has several possible applications. It can be used, as in our study, to find which of many possible mutations in an evolved E. coli strain contribute to a complex phenotypic trait. One could also use the same approach to hybridize the genomes of two E. coli strains that have been evolved or engineered to have an industrially useful property, such as producing increased amounts of a biofuel. The hybrid genomes may acquire a collection of some mutations from each ‘parent’ that performs better than either of the original strains. A related use,” he concludes, “would be to subtract deleterious mutations that sometimes accumulate over time in bacterial strains from a genome so that they’re not a drag on its growth or production capacity.” More information: Recursive genomewide recombination and sequencing reveals a key refinement step in the evolution of a metabolic innovation in Escherichia coli, Proceeding of the National Academy of Sciences Published online before print on December 30, 2013, doi:10.1073/pnas.1314561111 Related: 1Genomic analysis of a key innovation in an experimental Escherichia coli population, Nature 489(7417):513–518 (2012), doi:10.1038/nature11514 2Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli, Proceeding of the National Academy of Sciences, 105(23):7899–7906 (2008), doi:10.1073/pnas.0803151105 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. (Phys.org)—A pair of researchers, both with the University of Groningen in The Netherlands, has found that a certain songbird flies for 40 to 60 hours straight when it crosses the Sahara Desert as part of its diurnal migration pattern. In their paper published in Biology Letters, Janne Ouwehand and Christiaan Both describe attaching light and temperature sensors to several of the birds, retrieving the sensors and what the data revealed. Journal information: Biology Letters As the researchers note, over two billion songbirds cross the Sahara each year as part of their migration path, but because of their small size and huge numbers it has been nearly impossible to tell if the birds stop along the way or fly straight through—to date there has been conflicting information, due to an inability to connect hard data with actual bird sightings. In this latest effort, the researchers took a new approach, attaching tiny loggers to 80 pied flycatchers captured and released from a breeding ground in the Netherlands. The loggers recorded light and temperature readings every five to ten minutes over the entire course of a migratory trip. The birds were recaptured when they returned to the breeding grounds, a year later allowing for the data to be retrieved from the loggers. While it might seem like not much could be learned from such simple measurements, the team explains that putting the data together allowed for creating light curves, which allowed for calculating day length and from that approximate latitude. They were also able to calculate longitude by establishing the midpoint of the days and nights. In their study, the researchers report that they were able to retrieve 27 of the loggers, of which 15 contained useful data for both spring and fall migrations. They report also that some of the data was difficult to read, because the songbirds sometimes hide in dark places during daylight hours. But they also noted that on two occasions each, there were periods of smooth, clear data, suggesting that the birds were flying non-stop, for periods lasting from 40 to 60 hours.The finding, the team reports, is surprising, because it suggests that for large parts of their journey over the Sahara, the birds were flying in broad daylight—a time thought to be too hot for such travel. The team also found that the birds took a different route home, spending much of their long flight time, flying over the ocean, instead of the desert. © 2016 Phys.org Explore further How variation in body size correlates with en-route migration performance in a long-distance migratory songbird? More information: Janne Ouwehand et al. Alternate non-stop migration strategies of pied flycatchers to cross the Sahara desert, Biology Letters (2016). DOI: 10.1098/rsbl.2015.1060AbstractEach year more than two billion songbirds cross the Sahara, but how they perform this formidable task is largely unknown. Using geolocation tracks from 27 pied flycatchers, a nocturnally migrating passerine, we show that most birds made diurnal flights in both autumn and spring. These diurnal flights were estimated to be part of non-stop flights of mostly 40–60 h. In spring, birds flew across the Sahara, while autumn migration probably circumpassed part of the desert, through a long oversea flight. Our data contradict claims that passerines cross the Sahara by intermittent flight and daytime resting. The frequent occurrence of long non-stop flights to cross the desert shows migrants’ physiological abilities and poses the question why this would not be the general migration strategy to cross the Sahara. European Pied Flycatcher in Sweden. Credit: Wikipedia Citation: Study shows songbird travels nonstop for migration over Sahara (2016, April 18) retrieved 18 August 2019 from https://phys.org/news/2016-04-songbird-nonstop-migration-sahara.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. The behavior of the average [Mg/Fe], [Si/Fe], [Ca/Fe] and [Ti/Fe] abundance ratios of Gaia1 as a function of [Fe/H] (red point), in comparison with Galactic thin disk stars (grey points, Soubiran & Girard 2005). Credit: Mucciarelli et al., 2017. Explore further Citation: Researchers determine chemical composition of the stellar cluster Gaia1 (2017, June 13) retrieved 18 August 2019 from https://phys.org/news/2017-06-chemical-composition-stellar-cluster-gaia1.html More information: The chemical composition of the stellar cluster Gaia1: no surprise behind Sirius, arXiv:1706.01504 [astro-ph.SR] arxiv.org/abs/1706.01504AbstractWe observed 6 He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/MAGELLAN spectrograph. A possible extra-galactic origin of this cluster, recently discovered thanks to the first data release of the ESA Gaia mission, has been suggested, based on its orbital parameters. Abundances for Fe, alpha, proton- and neutron-capture elements have been obtained. We find no evidence of intrinsic abundance spreads. The iron abundance is solar ([FeI/H]=+0.00 +-0.01; sigma = 0.03 dex). All the other abundance ratios are, by and large, solar-scaled, similar to the Galactic thin disk and open clusters stars of similar metallicity. The chemical composition of Gaia1 does not support an extra-galactic origin for this stellar cluster, that can be considered as a standard Galactic open cluster. Researchers investigate chemical composition of globular cluster NGC 6362 Located some 15,000 light years away from the Earth (10 arcmin from Sirius), Gaia1 is an intermediate-age stellar cluster of about 22,000 solar masses. The discovery of the cluster, based on Data Release 1 (DR1) from ESA’s Gaia satellite, was reported in May 2017. DR1 and follow-up spectroscopic observations suggested extragalactic origin of Gaia1, however, more studies were needed in order to confirm this assumption.So a team of researchers led by Alessio Mucciarelli of the University of Bologna in Italy analyzed the spectroscopic data from the Magellan Inamori Kyocera Echelle (MIKE) spectrograph mounted on the Magellan II Telescope at Las Campanas Observatory in Chile. The spectra derived by Mucciarelli’s team included helium-clump stars of the Gaia1 cluster. The researchers obtained chemical abundances of iron (Fe), sodium (Na), magnesium (Mg), aluminium (Al), silicon (Si), calcium (Ca), titanium (Ti), barium (Ba) and europium (Eu) for six giant stars observed with the Magellan II Telescope.”We observed six He-clump stars of the intermediate-age stellar cluster Gaia1 with the MIKE/MAGELLAN spectrograph. (…) Abundances for Fe, Na, Al, Si, Ca and Ti have been derived from the equivalent widths of unblended transitions. (…) Abundances for Mg, Ba and Eu have been derived from spectral synthesis,” the astronomers wrote in the paper.The study reveals that Gaia1’s iron abundance is similar to that of our sun. Other abundance ratios are solar-scaled, comparable to our galaxy’s thin disk stars and open clusters of similar metallicity. According to the authors of the paper, the chemical composition of Gaia1 indicates that it formed from a gas that underwent chemical enrichment similar to that of the Milky Way’s thin disk. Thus, the results do not support the hypothesis that this cluster has an extragalactic origin.”A possible extragalactic origin of Gaia1 is not supported by the comparison between its chemical composition and that of other stellar systems. The galaxies currently populating the Local Group are more metal-poor than Gaia1 and they do not reach solar metallicity,” the researchers concluded.Therefore, the team classified Gaia1 as an unremarkable standard galactic open cluster. The researchers noted that the cluster’s position could suggest that it formed in the inner disk, progressively migrating toward higher galactocentric distance, which explains its possible peculiar orbit with respect to other open clusters.While the chemical composition of Gaia1 has been determined by Mucciarelli and his colleagues, there are still uncertainties about its orbital parameters. The researchers hope that the second Gaia data release will change this situation. (Phys.org)—Astronomers have determined chemical abundances of several elements for six giant stars of a recently discovered stellar cluster known as Gaia1. The results, available in a paper published June 5 on arXiv.org, reveal chemical composition of the cluster, providing important hints about its nature and origin. © 2017 Phys.org
The researchers also cut off the heads of specimens and tested them during the regeneration period—they were surprised to find the headless flatworms still shied away from UV light, suggesting light sensitivity in the skin. They also found that although the eyes regenerated after just four days, the flatworms were not able to respond to light again until a full week had passed; color preference did not appear again until after 12 days. Planarian flatworms are common around the globe. They are shaped somewhat like an eel with a flattened body and head. Most live in water, fresh or salty and some have a pair of dark eyes on their head. Planarian flatworms are also very well known in the biological world due to their unique ability to regenerate body parts—if you split one in two, for example, both parts will grow into a complete flatworm. Perhaps even more impressive, the flatworm can even regrow its head if lost. Prior research with the flatworms has shown that they are averse to light. In this new effort, the researchers sought to learn more about how flatworm vision works because of their ability to regenerate eyes when the head is lost.The team started by repeating prior experiments involving shining both white and UV light on test flatworms—they found that as expected, the flatworms swam away from either type. But they also found the flatworms disliked some colors less than others. When they had to choose between exposure to green or blue light, the flatworms chose green; they also chose red over green. This finding was surprising, considering the eyes of the flatworm are little more than cups containing photoreceptors—and their brains are little more than a few neurons. A closer look showed the flatworms were not actually able to make out the difference in color, but were responding instead to the brightness of the hues. Citation: Visual processing capabilities of flatworm found to be more complex than thought (2017, August 1) retrieved 18 August 2019 from https://phys.org/news/2017-08-visual-capabilities-flatworm-complex-thought.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. Flatworms avoid UV light even when their heads have been removed. Credit: Shettigar et al., Sci. Adv. 2017;3: e1603025 Schematic image of the planarian visual network. Planarians form the optic chiasm and visual axons project into the visual center for transmitting light information to the brain. The components of the planarian photoreceptor. The multicellular pigment cup produced by apposition of several pigment cells. Optic chiasm stained with a photoreceptor neuron marker. Scheme of planarian nervous system. Credit: Akash Gulyani Lab, inStem, Bangalore, India Schematic image of the planarian visual network. Planarians form the optic chiasm and visual axons project into the visual center for transmitting light information to the brain. The components of the planarian photoreceptor. The multicellular pigment cup produced by apposition of several pigment cells. Optic chiasm stained with a photoreceptor neuron marker. Scheme of planarian nervous system. Credit: Akash Gulyani Lab, inStem, Bangalore, India Schematics showing time line of return of different phototactic abilities during head regeneration in planarians. Few days after regeneration, worms sense light but have no ability to discriminate wavelengths, which is acquired gradually significantly later. Credit: Akash Gulyani Lab, inStem, Bangalore, India Schematics showing time line of return of different phototactic abilities during head regeneration in planarians. Few days after regeneration, worms sense light but have no ability to discriminate wavelengths, which is acquired gradually significantly later. Credit: Akash Gulyani Lab, inStem, Bangalore, India Explore further Journal information: Science Advances Flatworms can distinguish between different wavelengths of light even though their simple eyes only contain one type of receptor. Credit: Shettigar et al., Sci. Adv. 2017;3: e1603025 More information: Nishan Shettigar et al. Hierarchies in light sensing and dynamic interactions between ocular and extraocular sensory networks in a flatworm, Science Advances (2017). DOI: 10.1126/sciadv.1603025AbstractLight sensing has independently evolved multiple times under diverse selective pressures but has been examined only in a handful among the millions of light-responsive organisms. Unsurprisingly, mechanistic insights into how differential light processing can cause distinct behavioral outputs are limited. We show how an organism can achieve complex light processing with a simple “eye” while also having independent but mutually interacting light sensing networks. Although planarian flatworms lack wavelength-specific eye photoreceptors, a 25 nm change in light wavelength is sufficient to completely switch their phototactic behavior. Quantitative photoassays, eye-brain confocal imaging, and RNA interference/knockdown studies reveal that flatworms are able to compare small differences in the amounts of light absorbed at the eyes through a single eye opsin and convert them into binary behavioral outputs. Because planarians can fully regenerate, eye-brain injury-regeneration studies showed that this acute light intensity sensing and processing are layered on simple light detection. Unlike intact worms, partially regenerated animals with eyes can sense light but cannot sense finer gradients. Planarians also show a “reflex-like,” eye-independent (extraocular/whole-body) response to low ultraviolet A light, apart from the “processive” eye-brain–mediated (ocular) response. Competition experiments between ocular and extraocular sensory systems reveal dynamic interchanging hierarchies. In intact worms, cerebral ocular response can override the reflex-like extraocular response. However, injury-regeneration again offers a time window wherein both responses coexist, but the dominance of the ocular response is reversed. Overall, we demonstrate acute light intensity–based behavioral switching and two evolutionarily distinct but interacting light sensing networks in a regenerating organism. (Phys.org)—A team of researchers with the National Centre for Biological Sciences in India has found that the visual processing capabilities of the planarian flatworm are much more complex than has been thought. In their paper published on the open access site Science Advances, the team describes a series of experiments they carried out with the flatworm and what they learned about its visual processing capabilities. © 2017 Phys.org Researchers reveal bioelectric patterns guiding worms’ regenerative body plan after injury
The Capital will see a devotional music concert Bolava Vitthal brought by The Cultural Department – State Government of Maharashtra in association with Pancham Nishad. Pancham Nishad is an organisation set up to preserve and promote the rich traditional performing arts of India. The show will feature abhangs and devotional songs dedicated to Lord Vitthala on the eve of Ashadi Ekadashi.Jayateerth Mevundi, Rahul Deshpande, Devaki Pandit, Anand Bhate, Ranjani-Gayatri, Kaushiki Chakravarthy will enthrall the audience by rendering some of abhangs. After Delhi, the event will move on to Kolkata, Nashik, Kalyan (Mumbai suburbs), Mumbai, Bengaluru, Nagpur and Panaji (Goa).For the past eight years of Bolava Vitthal, eminent musicians like Ganasaraswati Kishori Amonkar, Ajit Kumar Kadkade, Aarti Ankalikar-Tikekar, Ashwini Bhide-Deshpande and Shaunak Abhisheki have performed on this platform. ‘Bolava Vitthal concerts have created its niche amongst the audience in the past eight years. Its pan India reach symbolises the popularity of devotional song genre,’ explained Shashi Vyas, organiser of the event.
My son is in 9th standard. He refuses to be a part of any social activity. He is always preoccupied with his computer and friends! How can we make him participate in our lives? I’m worried!Madhavi Kapur, New DelhiAdolescence is a transitional stage of physical and psychological human development that generally occurs during the period from puberty to legal adulthood. Your son is in this phase. A lot of new things will start and a lot of understanding and adjustment has to come from your end. However much aloof he might look, but you have to make that extra effort to involve him. Take him out to places he likes to visit. Spend time as a friend, interact and keep a close but distant eye on his life. Also Read – ‘Playing Jojo was emotionally exhausting’I met a guy in a chat box. He lives in USA and we have been dating since last 2 years. Of late he is insisting on my very personal photos. He has proposed marriage and is supposed to come to India around Jan next year. I love him but don’t feel comfortable with such requests. What should I do?Miss Singh, JalandharWell, I really don’t know what to suggest as there are two sides of the coin. Firstly, if the guy is a genuine one and wants to marry you then he can have some reasons to get really personal. This probably happens even in long distance relationships. On the other side, if the guy is fake (e-chats, e-dating cannot be blindly trusted) then sending any photos etc can be really dangerous! In today’s time, one cannot close eyes to trust and as the guy is a complete stranger, I would say – take it slow. Buy time, make excuses and insist on meeting the person first before committing to anything. Don’t take unwanted risks as heartbreaks take a lifetime to heal. Good luck dear! Also Read – Leslie doing new comedy special with NetflixI cannot last for more than a little while in bed. My wife is not fully satisfied and this is causing tension between us. I am very depressed about this. Name unknown, AgraDon’t be depressed as you are not the only one facing this problem, most men believe that they should last longer. And fortunately, there are ways with which you can last longer in bed. You can start by exercising your groin, arms and abdominal muscles. Consuming excessive alcohol and cigarettes could play spoilsport in a steamy night of passion. These products lead to fatigue and even affect your sex hormone levels causing poorer erections. Lastly, focus more on foreplay and don’t directly dive in. Indulging in some kissing and other acts can give her an orgasm that she deserves. I can’t get over my past marriage. My ex partner is married and looks happy too. I’m somehow not being able to get over the divorce and land up calling him at times. How can I forget him and move on? What do you say?Renuka, PatnaWell, it’s a matter of a decision that led to the divorce and it is a matter of another decision to stay away. It might take many weeks or years to get over this broken marriage but as your partner is already settled, you should refrain from communicating. Focus and divert your attention on other things. Keep yourself busy with work and friends and I sincerely wish you the power to conquer all temptations.Have a love or life query you cannot find an answer to? Send your questions to – email@example.com
US President Barack Obama met his Russian counterpart Vladimir Putin three times on the sidelines of an Asia-Pacific summit on Tuesday, the White House said.‘Their conversations covered Iran, Syria, and Ukraine,’ National Security Council spokesperson Bernadette Meehan told reporters, adding that in total they met for 15 to 20 minutes.Obama has insisted that Russia stop supporting pro-Russian separatists in eastern Ukraine while Putin has dismissed the sanctions that the United States and the European Union have slapped on Moscow as counterproductive.Obama’s deputy national security adviser, Ben Rhodes, told reporters in Beijing on Tuesday that any encounter would be a chance for Obama to remind the Russian leader of his promise to help resolve the Ukraine crisis peacefully.‘President Putin knows full well where we stand,’ Rhodes said.