Tag: 爱上海同城龙凤

DNA fails to secure seats but urges unity among Bahamians

first_imgFacebook Twitter Google+LinkedInPinterestWhatsAppBahamas, May 11th 2017: The Democratic National Alliance, described as the spoiling vote in the lead up the 2017 polls, failed to secure any seats in the elections.DNA Candidate for Killarney, Arinthia KomolafeWith the FNM securing the major portion of the electoral pie, the DNA is still expressing confidence in bringing the change its supporters hope to see in Bahamas one day. Following the results last night, the DNA took to its Facebook page together with many of its candidates, to thanks its supporters for their votes and support during the campaign. Its official page read “Fighting for what you believe in is never wrong. THANK YOU from the bottom of our hearts to all of you who voted #forabetterlife. May God Bless the Commonwealth of The Bahamas, the new incoming Government of The Bahamas, and all of our people”.Its Killarney Candidate, Arinthia Komolafe, who lost to Prime Minister Elect, Dr.Hubert Minnis, counted it a privilege in running against Minnis, and extended heartfelt congrats to him and his party. She says her work within the Constituency will continue, as she intends to implement the plans that laid out in her platform.DNA Candidate for Golden Isles, Stephen GreensladeDNA Candidate for Garden Hills, Youri KempYouri Kemp, candidate for Garden Hills also thanked voters who supported him and campaigned along his side this year. Kemp urged residents to trust in God at this time, as he has allowed the people to see what they needed to see for them to cast their vote for who they wanted to govern our country. In response to the DNA’s numbers, Kemp says “Massive election losses like this are nothing to do with regard to the quality or calibre of persons of anyone who did not win, but it had to do with glaring factors that the Bahamian people saw fit to deal with as a priority for them at this time”.Golden Isles Candidate, Stephen Greenslade called on the people to focus on moving our country forward by positively contributing in whatever small way to that effort, as we must work together as a nation to reach higher heights.#MagneticMediaNews#BahamasGeneralElections2017#DNACandidatesReactToLoss Related Items: Facebook Twitter Google+LinkedInPinterestWhatsApplast_img read more

Klopp reveals he had to lift dull atmosphere at Liverpool

first_imgLiverpool manager Jurgen Klopp has revealed he had to improve the ‘depression-like’ atmosphere at the club with his high-pressing style on his arrival at the club.Klopp insists the Reds needed a lift when he arrived in 2015 and that approach has set the platform for their title challenge this season.The former Borussia Dortmund manager replaced Brendan Rodgers as Liverpool manager in October 2015, leading the club to an eighth place finish in the 2015/16 season as well as reaching the finals of the EFL Cup and UEFA Europa League.Klopp admits to changing his style this season and the weaknesses of his philosophy during his early years in charge of the Merseyside club.However, the German insists the initial style of play was necessary to lift the mood around the club and has ultimately benefited the club in the long-term.“Of course, we had to develop. That’s what we do since I came in,” Klopp told ESPN.Roberto Firmino, LiverpoolVirgil van Dijk praises Roberto Firmino after Liverpool’s win Andrew Smyth – September 14, 2019 Virgil van Dijk hailed team-mate Roberto Firmino after coming off the bench to inspire Liverpool to a 3-1 comeback win against Newcastle United.“First, because it felt a little bit like a depression here. I think it made sense to be extremely lively. Yes, to make mistakes, but be very lively, very direct, very energetic.”“It was not perfectly organised. In a few parts we were pretty quick with organisation, but it was only the offensive pressing pretty much. All the other departments we were a bit random, I would say.”“That, of course, improved a lot, so we are now working together with big parts of the squad for more than three years, which is brilliant. And all the other players which we picked, they adapted pretty well because of different reasons. One is only quality and the other thing is that they have played similar styles of football in the club they were in before.”“It was clear, we have to become more stable. That’s what we try to do. It was a big thing in the summer obviously and the boys did the job so far. That’s why we could get the results we could get.”last_img read more

Reversals of Earths Magnetic Field Explained by Small Core Fluctuations

first_img Explore further Although volcanic basalt reveals when reversals occurred, it’s much more difficult to find evidence for why or how the Earth’s magnetic field reverses. In a recent study, scientists from the Ecole Normale Supérieure and the Institut de Physique du Globe de Paris, both in Paris, have proposed a general mechanism that provides a simple explanation for field reversals. In their model, small fluctuations in convective flow in Earth’s core can push the planet’s sensitive magnetic system away from one pole toward an intermediate state, where the system becomes attracted to the opposite pole. “We have found a mechanism that gives simple explanations of many features of the reversals of Earth’s magnetic field,” François Pétrélis of Ecole Normale Supérieure told PhysOrg.com. “In particular, it explains the existence and the shape (slow phase followed by fast phase) of reversals, the existence and the shape of aborted reversals (‘excursions’), the statistical properties of reversals, and the possibility for very long durations without reversals (‘superchrons’).”At present times, the Earth’s magnetic field can be described as a magnetic dipole, with the magnetic south pole currently located near the Earth’s geographic north pole, and the magnetic north pole near the geographic south pole (both magnetic poles are misaligned along the Earth’s rotational axis by about 11.3 degrees). The existence of such a long-lived magnetic field can be explained by dynamo theory, which describes how a convective, electrically conducting fluid that rotates can maintain a magnetic field. As the scientists suggest, the reversal mechanism relies on the existence of a second magnetic mode, in addition to the dipolar field. The presence of a second mode, such as a quadrupolar field, can have significant effects on how the magnetic system reacts to changes in equatorial symmetry. As the researchers explain, the equator can be thought of as a plane of symmetry, and the convective flow in the Earth’s outer core is usually north-south symmetric. Previous studies on paleomagnetic data have proposed that reversals involve an interaction between the dipolar and quadrupolar modes, which would correlate with changes in equatorial symmetry. In support of this idea, some recent numerical simulations have shown that reversals do not occur when the convective flow remains equatorially symmetric. (PhysOrg.com) — Based on studies of old volcanic basalt, scientists know that the Earth’s magnetic field reverses at irregular intervals, ranging from tens of thousands to millions of years. Volcanic basalt rock contains magnetite, and when the rock cools, its magnetic properties are frozen, recording the Earth’s magnetic field of the time. With this data, scientists estimate that the last magnetic field reversal occurred about 780,000 years ago. According to a new model, small fluctuations in convective flow in Earth’s core can explain how the Earth’s magnetic field reverses. Image credit: Wikimedia Commons. “The quadrupolar field (it is likely to be a quadrupole but another structure could be possible) is also generated by the flow of the liquid core of the Earth, exactly like the dipolar field,” explained the researchers. “Most of the time, we observe a dipolar field because it is more easily generated by the flow, but in other conditions a quadrupolar field could be maintained, and this occurs in a temporary manner during a reversal.”To further explain the dipole-quadrupole interaction, the scientists invoked a model that was recently used to describe the dynamics of a magnetic field generated in a very different system: a lab experiment involving a von Karman swirling flow of liquid sodium (which, like the Earth’s magnetic field, is generated by the dynamo effect). The scientists suggest that a general mechanism could explain both magnetic fields, independent of the different symmetries and velocities of the two systems.“We have shown that if the dipolar field of Earth is coupled to another magnetic mode (a quadrupolar field, for instance), this coupling provides a path to flip the dipole to its opposite,” the scientists said. “If this coupling is strong enough, the magnetic field will spontaneously oscillate between the two modes and their opposite polarities. We will then observe periodic reversals of the magnetic field (this is the case of the solar magnetic field, for which the period is 22 years). In the case of Earth, the coupling is not strong enough, and oscillations are not observed. Velocity fluctuations in the liquid core are then needed to trigger a reversal.”In the model, small fluctuations in convective flow can push the system away from one pole toward the intermediate quadrupolar state, where it becomes attracted to the opposite pole. A reversal occurs in two phases: a slow phase where the fluctuations are the motor of the evolution, and a fast phase during which the dynamics does not rely on the fluctuations. The first phase, during which the dipole amplitude decreases slowly, seems to last around 50 kiloyears (30,000-70,000 years). The second phase, which starts when the dipolar mode vanishes, is quite faster: 10,000 years are required for the dipole to recover with the opposite polarity. Sometimes, at the end of the first phase, the system may simply return to the initial pole, which is called an “excursion” when it occurs on Earth. However, if the system does reverse, the behavior happens relatively abruptly. In addition, the system usually overshoots immediately after reaching the opposite pole. The scientists noted that the amplitude of the fluctuations does not need to be large: “Fluctuations of the flow do not switch off the magnetic field and then regenerate it with the opposite polarity,” they said. “In contrast, the dipolar field continuously changes shape during a reversal because the amplitude of the other mode (the quadrupole, for instance) continuously increases, whereas the dipole decreases. When the dipolar component vanishes, it can increase again with the opposite polarity whereas the amplitude of the other mode decreases.”The model shows that the duration of the magnetic field in one state depends on the intensity of the convection fluctuations and also on the efficiency of the coupling between the two modes. Even a moderate change in convection can greatly affect the magnetic field polarity duration, which could account for “superchrons” – very long periods without geomagnetic reversals. Although little is known about the actual flow inside the Earth’s core, recent observations have shown that the ends of superchrons are often followed by major flood basalt eruptions, which are likely to produce equatorial symmetry breaking of convection at the core-mantle boundary, in support of the scientists’ model. More information: Pétrélis, François; Fauve, Stéphan; Dormy, Emmanuel; and Valet, Jean-Pierre. “Simple Mechanism for Reversals of Earth’s Magnetic Field.” Physical Review Letters, 102, 144503 (2009).Copyright 2009 PhysOrg.com. All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of PhysOrg.com.center_img Simulations shed light on Earth’s history of magnetic field reversals Citation: Reversals of Earth’s Magnetic Field Explained by Small Core Fluctuations (2009, April 23) retrieved 18 August 2019 from https://phys.org/news/2009-04-reversals-earth-magnetic-field-small.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.last_img read more

The origins of polarized nervous systems

first_imgComb Jelly from phylum Ctenophora. Credit: ctenophore.wikispaces.com (Phys.org)—There is no mistaking the first action potential you ever fired. It was the one that blocked all the other sperm from stealing your egg. After that, your spikes only got more interesting. Waves of calcium flooding the jointly-forged cell stiffened its glycoprotein-enhanced walls against all other suitors and kicked off the developmental program ultimately responsible for constructing your brain. Unlike the nervous systems of the lower forms of life, our neurons have a clearly polarized form—a single output axon projecting far to parts unknown is charged by input dendrites feeding on the local metabolic soup de jour. The origins of this polarity in neurons, and therefore in nervous systems in general, are written in the primitive body plans of the mostly gelatinous organisms still hailing intact across deep time. Journal information: Journal of Experimental Biology 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: The origins of polarized nervous systems (2015, March 3) retrieved 18 August 2019 from https://phys.org/news/2015-03-polarized-nervous.html Complex nerve-cell signaling traced back to common ancestor of humans and sea anemones How a blunt multipurpose neuronal toolkit that originally evolved to nourish was morphed into the precise cellular utensils we now use to mince the world is the subject of a new special issue in the Journal of Experimental Biology (JEB). The story of the acquisition of polarity, or rather the loss of universality, in the flow of resource through crude nerve nets is the story of our brains. Last year,Tim Jegla from Penn State published work showing that the human Erg potassium channels that are tuned to repolarize the long action potentials underlying the strong muscular contractions of our hearts have their origins in the earliest nervous systems ever evolved. Since then he has been piecing our brains together by tracing the evolution of related channels like the EAG potassium channels, and the so-called Shaker potassium channels in various primitive organisms. The creatures that have been the most informative mostly fall into taxonomic groups of typically radially-symmetric animals named with a strange variation on the letter C. The ‘cnidarians’ are animals like hydras and the true jellyfish, while the ‘ctenophores’ are the comb jellies that swim with cilia. In an article on polarity written together with Melissa Rolls, Tim explores how the positioning of different kinds of channels by the cytoskeleton (at places like the axon initial segment, nodes, and dendrites) is crucial for establishing directional signalling in neurons. So I asked him point blank if he could nail down when polarity first evolved. He said it was likely in an ancestor of the parahoxozons, a group defined by their possession of at least one of the Hox/ParaHox genes associated with the the specification of the body axis. With genetic experiments now in progress in his lab Jegla is looking for indications that polar neurons exist, contrary to the current literature, even in the lowly sea anemone. As cnidarians, anemone are privy to the benefits of parahoxozoans, something the ctenophores cannot claim. More information: Journal of Experimental Biology, jeb.biologists.org/content/current © 2015 Phys.org In looking for larger developmental trends in which to anchor the idea of increased polarity, or loss of flexibility in neurons, ctenophores may have other secrets to tell. One author writing in the special issue of JEB suggests that recent whole genome data puts ctenophores as a sister group to all other animals, placing them at the earliest branching lineage—a move which would make them a more basal metazoan than even SpongeBob himself. Two factors which complicate such analysis are convergent evolution and the loss of genes and function. We might imagine that the possibility of having at least two independent origins for neural systems exists regardless of which lineage was prior.It has been known since the work of Chun in 1880 that when ctenophore blastomeres are separated at the two-cell stage each half-embryo develops exactly half of adult structures. It seems that this high degree of determinism at the organism level, which fades in the progression of species, contrasts with the aquisition of specification at the cell level. Among the important proteins known to exist in these primitive organisms are various kinds of G-protein coupled receptors and gap junctions. Originally it looks like these proteins played important roles in cell adhesion and communication, and therefore in early development and specification of the body plan. Enzymes to synthesize and transport neurotransmitters were also present early on. A trend in moving to more advanced body plans, and neurons, is the restriction of the expression of these transmitter systems to specific cells. On top of this there is an inexorable refinement of multipurpose symmetric synapses into asymmetric synaptic diodes, with concommitant exclusivity of transmitter profile in both dense core and clear vessicles. In creature like planarians, worms, or flies, the percentage of neurons we might call ‘polar’ becomes an increasingly important thing for us to take account of. In C. elegans for example, many neurons, with the exception of the elaborate and highly branched sensory neurons that span the whole body, are fairly simple with just a few processess containing synapses that can be both pre and post synaptic. The neurons of many insects, like drosophila, are conspicuous for their dense regions of idiosyncratic branching where the terms dendrite or axon would seem to have little meaning. While the neurons of higher and larger vertebrates are expected to in a sense ‘feel’ every spike they might pull off throughout the whole neuron, it paradoxically seems that tiny invertebrate neurons none-the-less are more likely to contain isolated domains of protected metabolic and electrical activity. The details of all this are to be found at the molecular level, which at this time in the history of neurobiology means the the directions of the ‘plus’ and ‘minus’ ends of various cytoskeletal proteins, and the preferences of the motors that ride them in either direction. Like vertebrates, drosophila have axons that exclusively use plus-end-out microtubules. However, although their dendrites similarly are distinguished by the presence minus-end-out microtubules, one surprise was that almost all of their dendrites were this way. The kicker is that they start out with a even mix like vertebrates do, but over time somehow weed them out. An important element in any potential theory of neurons would be the role of the cell body (the nucleus, centriole and primary cilium) in the ongoing specification of the larger tree of axons and dendrites. A cell body that stands largely aloof from them, whether transiently or permanently, would appear to lose some of the authority it might have if interposed instead between them.The unique geometry of the pseudounipolar neurons of our dorsal root ganglion has been known for a while, but only more recently has the frequent presence of axons sprouting from dendrites in our hippocampus and cortex been appreciated. In seeking explanations for the structure of such neurons the influences of mitochondria in various states of performance and lifecycle should not be underestimated. In fact, mitochondria figure importantly in the entire evolutionary curiosity we have tried to lay out here. The same article above which stirred up question surrounding the primitive phylogeny of sponges also explored newly identified trends that emerge in looking at the sizes and contents of the genomes of mitochondria across metazoans—but that is probably a topic sufficient for another post. 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