Tag: 重庆有几个后花园

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Vardy symbolising decline of champions Leicester

first_img BURNLEY vs BOURNEMOUTH SWANSEA vs SUNDERLAND 7 a.m.: Chelsea vs West Brom 9:15 a.m.: – Man United vs Tottenham – Southampton vs Middlesbrough 11:30 a.m.: Liverpool vs West Ham Watford vs Everton 10 a.m.: – Arsenal vs Stoke City • Burnley vs Bournemouth – Hull City vs Crystal Palace – Swansea vs Sunderland 12:30 a.m.: • Leicester vs Manchester City There’s a meeting tomorrow between two of the league’s four English managers. What is surprising is that only Bournemouth manager Eddie Howe, rather than Burnley counterpart Sean Dyche, was seriously linked with the England coaching job when it came up twice this year. In their second-ever top-flight campaign, Bournemouth are 10th in the 20-team standings after beating Liverpool last weekend by winning 4-3 from 3-1 down. Burnley, after making an instant return to the Premier League, are 15th. 7:30 a.m.:center_img With only one win in seven games as Swansea manager, Bob Bradley has seen his new team slide to the bottom. The American’s dire introduction to the Premier League was heightened when his disjointed team lost 5-0 at Tottenham last week. Is Bradley’s job already under threat? “You go in every day and at any moment the club can say ‘We need to make a change,'” Bradley said yesterday. “But if you worry about that, the players will spit you out fast. They will see through you. If I am telling the players they have to look adversity in the eye and have some courage, then I have got to do that, too.” Bradley shouldn’t give up hope. He only has to look to Sunderland, the team that was last when he took charge in south Wales and play Swansea tomorrow. Sunderland have hauled themselves to a point from safety by winning three of their last four games under David Moyes. LONDON (AP): After spending last season as one of the key forces behind Leicester’s rise to the Premier League title, Jamie Vardy is now the symbol of the team’s alarming decline. The rough diamond unearthed in non-league football helped power Leicester to their first English title by scoring 24 goals. Defences struggled to contain him as he scored in a record 11 consecutive Premier League games from August to November 2015. Now, the striker can barely get a shot on target and Leicester are struggling because of it. If Vardy fails to score against Manchester City on Saturday, it will be 11 consecutive games without a Premier League goal. And if results go against Leicester, the team could start the game in the relegation zone. The 29-year-old Vardy rejected the chance to join perennial top-four team Arsenal to see if Leicester could build on their fairy-tale season. That has happened in Europe, with Leicester qualifying for the round of 16 in their Champions League debut as group winners. Leicester collected as many points in the six group games as in the 14 Premier League matches so far: 13. Vardy didn’t find the net once in five European games before being rested in Wednesday’s 5-0 loss to FC Porto, which didn’t affect Leicester’s status as group winners but was a high-profile humiliation. Vardy has only contributed two Premier League goals and managed a mere four shots on target in the competition dominated by Leicester so unexpectedly last season. What’s also been noticeable is how Vardy is no longer linking so effectively with Riyad Mahrez – if at all – as the supply line for scoring opportunities has fractured. Unless the symbiotic relationship between Vardy and Mahrez rejuvenates in the second half of the season, Leicester are in real danger of seeing their three-season stay in the Premier League end on the first anniversary of their title triumph in May. “Of course he’s not happy,” Leicester manager Claudio Ranieri said of the central England club’s Thai owner. “No one at the club is.” The one player Leicester couldn’t persuade to stay off season is being sorely missed. N’Golo Kante produced a league-leading 175 tackles and 156 interceptions last season before joining Chelsea. The midfielder would seem to perform the work of two men when he was on the field and without him, Leicester’s defence has seemed easier to break through. Many at the club have publicly attributed the drop in domestic form to the desire to impress on the continent. Now there are no distractions for the next two months before the Champions League knockout phase begins. The visit of Manchester City is a timely reminder about the fate of champions. City were the last team to follow a title triumph with relegation, far back in 1938. City’s current mission is coping for the next four games without Sergio Aguero, with Kelechi Iheanacho replacing the banned striker in the starting lineup. City are fourth in the standings, four points behind Chelsea. Sunday On This Weekendlast_img read more

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The Evolution of Electrical Engineering:  An Imaginary Tale

first_imgNerves carry electrical impulses.  Ipso facto, they are subject to laws of physics concerning conductance, capacitance, and resistance.  Getting a signal from one end of an animal to the other in time can be a matter of life and death.  In order to maintain optimum levels of electrical conductivity to meet their lifestyle requirements, animals possess numerous adaptations to increase throughput.  In a paper in Current Biology,1 D. K. Hartline (U of Hawaii) and D. R. Colman (McGill U, Quebec) described how these adaptations fall into two main categories:Nervous systems have evolved two basic mechanisms for increasing the conduction speed of the electrical impulse.  The first is through axon gigantism: using axons several times larger in diameter than the norm for other large axons, as for example in the well-known case of the squid giant axon.  The second is through encasing axons in helical or concentrically wrapped multilamellar sheets of insulating plasma membrane – the myelin sheath.  Each mechanism, alone or in combination, is employed in nervous systems of many taxa, both vertebrate and invertebrate.  Myelin is a unique way to increase conduction speeds along axons of relatively small caliber.  It seems to have arisen independently in evolution several times in vertebrates, annelids and crustacea.  Myelinated nerves, regardless of their source, have in common a multilamellar membrane wrapping, and long myelinated segments interspersed with ‘nodal’ loci where the myelin terminates and the nerve impulse propagates along the axon by ‘saltatory’ conduction.  For all of the differences in detail among the morphologies and biochemistries of the sheath in the different myelinated animal classes, the function is remarkably universal.Hartline and Colman went on to describe how the insulation provided by myelin increases throughput dramatically:Myelin sheaths are frequently associated with rapid reactions, especially in invertebrate taxa.  For fibers of a few microns or more in diameter, myelin speeds the conduction of nerve impulses by a factor of ten or more compared to unmyelinated fibers of the same diameter.  This increases the nervous system’s information processing capacity and delivery speeds, decreasing reaction times to stimuli, increasing temporal precision, more closely synchronizing spatially distributed targets (such as different regions of a muscle sheet), and providing for shorter delays in feedback loops (for example in muscle control).  Because less current is needed to satisfy the charging needs of myelinated fibers, mean sodium channel densities averaged over the length of a fiber are much lower than for unmyelinated ones.  This results in a smaller ionic imbalance that must be restored after an impulse passes and confers a several hundred-fold improvement in metabolic efficiency for recouping the energy cost of nerve impulse traffic.  For a nervous system such as ours, which already accounts for 20% of the body’s resting metabolic energy budget, this is not an inconsequential advantage.  Another advantage is economy of space: to achieve the same ten-fold improvement on conduction speed through increasing axonal diameter, axons would have to be 100 times larger (with a comparable scale-up in soma size to accommodate the metabolic needs).  Imagine yourself with a 100-fold thicker spinal cord!    The authors were also interested in how these adaptations could have evolved.  Consider the scope of their puzzle:Both mechanisms (axon gigantism and insulation) are dispersed throughout the animal kingdom.There are great evolutionary distances between similar adaptations.There are no transitional forms.There are no clues from fossils.So despite confidence that these adaptations did evolve, they admitted they had only speculation about natural selection might have achieved it:So ancient is its evident appearance in each of these lines, and so sophisticated its morphological and chemical structure, that its exact origin in most of those lines is hard to establish.  Even in vertebrates there is a great evolutionary distance between the unmyelinated hyperoartia (lampreys) and the gnathostomes.    The initial steps in the evolution of myelination may not, however, be that difficult to reconstruct.  Electrically sealing together two apposed membrane surfaces over a small region of axon decreases its transverse capacitance and proportionately speeds impulse propagation along it.  The sealing can be achieved by narrowing the conductive space, either cytoplasmic or extracytoplasmic, between adjacent axonal and/or glial membranes … or through impermeable specializations at margins, for example precursors of septate junctions.  Even the random sealing of patches of single-layer glial membrane over half of an axon’s surface is predicted to increase conduction speed by about 20%.  Once such a process has started, it is not difficult to imagine a sequence of small improvements driven by natural selection that would ultimately lead to the complex structures we see today.  This is speculative, however; no cases have been described so far of ‘intermediate stages’ in extant groups.  Developmental sequences, the lack of fossil records and the paucity of candidate molecular precursors so far identified have made the task more difficult.  Perhaps better insight will be gained through increased attention to myelin evolved in the invertebrates. (Bold and underlining added.)1D.K. Hartline and D.R. Colman, “Rapid Conduction and the Evolution of Giant Axons and Myelinated Fibers,” Current Biology, Vol 17, R29-R35, 09 January 2007.These guys started right off the bat with the BAD strategy (brazen assertions of dogmatism): “Nervous systems have evolved…”  Ahem–there are a lot of people who do not accept that.  Your evidence, please?  Some fossils, perhaps?  A long sequence of intermediate steps, each with increased survival value?  A clear phylogenetic pattern?  None of the above.  So here is their argument: “it is not difficult to imagine…”    If you thought science was about evidence and proof, welcome to the Storybook Land of the Darwinist (see 12/22/2003 commentary).  Instead of launching into another sermon against imagination in science as a substitute for evidence, this time we will let the Good Book do it for us.  Substitute Darwin and natural selection where appropriate:God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. (Genesis 6:5)the imagination of man’s heart is evil from his youth. (Genesis 8:15)Why do the heathen rage, and the people imagine a vain thing? (Psalm 2:1)they imagined a mischievous device, which they are not able to perform. (Psalm 21:11)They also … imagine deceits all the day long. (Psalm 38:12)Which imagine mischiefs in their heart (Psalm 140:2)Deceit is in the heart of them that imagine evil (Proverbs 12:20)neither shall they walk any more after the imagination of their evil heart. (Jeremiah 3:17)But they hearkened not, nor inclined their ear, but walked in the counsels and in the imagination of their evil heart, and went backward, and not forward. (Jeremiah 7:24)But have walked after the imagination of their own heart, and after Baalim, which their fathers taught them. (Jeremiah 9:24; for fun, try substituting Darwin for Baalim here)Yet they obeyed not, nor inclined their ear, but walked every one in the imagination of their evil heart (Jeremiah 11:8)This evil people, which refuse to hear my words, which walk in the imagination of their heart (Jeremiah 13:10)And ye have done worse than your fathers; for, behold, ye walk every one after the imagination of his evil heart (Jeremiah 16:12)And they said, There is no hope: but we will walk after our own devices, and we will every one do the imagination of his evil heart. (Jeremiah 18:12)Thou hast seen all their vengeance and all their imaginations against me. (Lamentations 3:60, 61)What do ye imagine against the Lord? (Nahum 1:9)He … hath scattered the proud in the imagination of their hearts. (Mary, praising God in Luke 1:51)Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. (Paul, in Romans 1:21)Paul continues, “professing themselves to be wise, they became fools.”  Here you have witnessed academic elite scientists claiming, out of thin air, without any evidence, that sophisticated electrical engineering emerged by mistake!  Does the shoe fit, or what?  They have glorified their own speculations.  They have imagined a fable that runs 180 degrees contrary to the evidence.  They have totally refused to bend their stiff necks to alternative explanations, like intelligent design.  They have shown themselves to be dogmatist wolves in scientist sheep’s clothing, walking after the imaginations of their own foolish hearts.    So we end with more advice from the Apostle Paul: words that would have been understood as a mission statement by many of the founders of science: “Casting down imaginations, and every high thing that exalteth itself against the knowledge of God” (II Corinthians 10:4).(Visited 10 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

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Leaf Assumption Challenged: Affects Climate Modeling

first_imgA reasonable-sounding assumption has been overturned, leaving climate models in upheaval.  The assumption was that leaf temperature stays in equilibrium with air temperature.  It doesn’t.  Leaves are hotter than assumed during active periods of growth, such as at midday in the growing season.  They maintain a relatively constant temperature through their own biological air conditioning, regardless of what the weather is doing.  This affects the interpretation of oxygen isotopes in wood extracted from tree rings, which in turn affects inferences about past climate.  The story came unraveled in Nature last week.1    Scientists have used the ratio of oxygen-16 to its heavier sibling oxygen-18 as a proxy for climate variations.  The interpretation, however, assumed that leaves are in equilibrium with ambient temperature.  Helliker and Richter (U of Pennsylvania) found that leaves can be 10° C hotter than air temperature, and were almost uniformly warm across a wide range of habitats.  This also affects calculations of relative humidity – a function of temperature.  “Our results explain this observation over a broad climatic range and further suggest that the overarching trend is to maintain leaves at an optimal temperature irrespective of mean climate,” they said.  F. I. Woodward (U of Sheffield, UK), commenting on this paper in the same issue of Nature, 2 explained, “During the growing season, with photosynthesis at its peak, leaf temperatures remain constant over a wide latitudinal range.  This is a finding that overturns a common assumption and has various ramifications.”    One key ramification relates to climate models.  Scientists have built models of past climate on the assumption that the oxygen ratios they measured in wood reflected the air temperature during the growing season.  Now, it appears that assumption is misguided.  Pine needles, for example, cannot be modeled in isolation, because they usually are in tight clusters.  It seemed reasonable that a pine needle, exposed on all sides to the air, would be the same temperature as the air.  But in the dense forest canopy, clusters of densely-packed needles create their own microclimate as the needles actively expend energy manufacturing sucrose in response to photosynthesis.  Leaf temperatures, therefore, can be much higher than air temperature – and relative humidity correspondingly lower.  This affects the rates at which oxygen-16 and oxygen-18 diffuse and become incorporated into the cellulose in tree rings.    Woodward summarized the potential impact of this finding on climate models: “The fact that vegetation canopy rather than leaf morphology dominates temperature control in the forests sampled by Helliker and Richter suggests the need for greater emphasis on understanding how the canopy responds to climate change, and to global warming in particular.”  The authors also suggested that the finding will force researchers to modify estimates of water loss in the forest canopy.  In addition, theories about how climate affects leaf evolution have been called into question.1.  Brent R. Helliker and Suzanna L. Richter, “Subtropical to boreal convergence of tree-leaf temperatures,” Nature 454, 511-514 (24 July 2008) | doi:10.1038/nature07031.2.  F. I. Woodward, “Ecology: Forest air conditioning,” Nature 454, 422-423 (24 July 2008) | doi:10.1038/454422a.Do you see how unquestioned assumptions become weak links in chains of reasoning on which politicians and societies put their trust?  Maybe the modifications to theory required will not be dramatic in this case, but they could be.  Scientists had treated oxygen ratios in tree rings as bona fide scientific evidence of past climate conditions.  Scenes of scientists measuring isotope ratios to high precision in labs make for impressive visuals in documentaries.  The lay public becomes persuaded that scientists have a virtual crystal ball into the past.  All the while they were not measuring climate – they were measuring local microclimates right at the leaf surfaces, which can be significantly warmer than the air just a meter away.  Plants have a thermostat of their own that maintains near-constant temperatures during the growing season.  These temperatures are the ones recorded in the wood – not the climate conditions.  This little “whoops” discovery should teach us a healthy caution and skepticism about proxy measurements employed matter-of-factly by scientists.  We can all learn, furthermore, to question our own assumptions, as reasonable as they may seem to us.(Visited 8 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more

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America Is Great. Not Perfect.

first_img Get the Free eBook! Want to master cold calling? Download my free eBook! Many would have you believe that cold calling is dead, but the successful have no fear of the phone; they use it to outproduce their competitors. Download Now What makes America great isn’t that it was, has, or ever will be perfect.What makes America great is that the ideals on which the nation was founded still command us to right what’s wrong, to struggle to live up to our ideals, that all men are created equal, that we are endowed by our creator with the unalienable rights of Life, Liberty, and the pursuit of Happiness.What makes America great is that despite our imperfections we are still struggling towards the perfection of these ideals. Even though we may disagree with each other on how best to live by those ideals and how best to govern ourselves, there isn’t any real disagreement as to what those ideals are. There is no disagreement that our ideals are good, and true, and beautiful.Perfection isn’t what makes America great. What makes America great is the fact that we continue to try to perfect ourselves against our ideals. This struggle is long and arduous. But we progress, sometimes too slowly, but mostly in the right direction.That the Revolution continues unabated after 240 years is what makes America great.last_img read more

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