How Tall Can a Tree Grow?

December 19, 2019

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first_img130 meters (426 ft) seems to be the upper limit on the height of a tree, say researchers from Humboldt State, Northern Arizona University and Pepperdine University, in the April 22 issue of Nature.1  To find this out, they had to establish working stations at the tops of northern California redwoods, the tallest trees on earth (the current record holder is 369.75 feet, the height of a 36-story building).  Ian Woodward calls their in situ measurements of photosynthesis at heights of over 360 ft. a “remarkable achievement.”2  The team shot arrows over the tops of tall northern redwoods, then pulled up ropes and climbed hundreds of feet into the crown branches to take their measurements of water pressure, leaf mass, carbon dioxide exchange, and light environment.  Since the tallest trees, which are estimated to have been growing for 2000 years, have not reached the theoretical limit, they could continue growing for some time.    Koch et al. determined that the limiting factor is ability to pump water against the competing forces of gravity and friction, which increase with height.  Transpiration through the leaves creates a suction in the woody vessels that pulls the water upward until cavitation occurs, when an embolism forms that collapses the water flow.  They found that the top leaves get smaller and denser at the top, and less photosynthesis occurs, due to the challenge of delivering water hundreds of feet off the ground.  The northern redwoods are efficient drawers of water, Woodward says:Tall trees use considerable quantities of water.  For example, a 45-m redwood uses about 600 kg of water each day, a figure that increases substantially with height and size.  It seems surprising, therefore, that the redwoods live in a climate with an annual dry season of 3-4 months.  Offsetting such an apparent drawback, however, is the oceanic influence on local climate, which means that dry-season fog occurs for up to two weeks at a time: fog reduces transpiration, a benefit in the dry season.  Moreover, tall trees actually increase the interception and capture of fog coming in off the sea, to the tune of 34% of the annual incidence of precipitation; in their absence, the precipitation input from fog is halved.Woodward finds it interesting that Koch’s team began their research in 1988 on the lowly radish, and now they have continued on the tallest plants in the world.  “Yet that is no real surprise,” he notes: “despite the very different packaging and longevity of the two species, their physiological processes are much the same.”See also the BBC News writeup on this research paper.1Koch, Sillett, Jennings, and Davis, “The limits to tree height,” Nature 428, 851 – 854 (22 April 2004); doi:10.1038/nature02417.2Ian Woodward, “Plant science: Tall storeys,” Nature 428, 807 – 808 (22 April 2004); doi:10.1038/428807a.Here is a good example of science as it should be done.  Excellent field work, and no storytelling about evolution.  As remarkable as today’s giant trees are, there were probably even bigger ones in the past.  Yellowstone in Wyoming and Florissant Fossil Beds in Colorado have fossilized Sequoia stumps, and redwood fossils have been found even near the Arctic circle (see 03/22/2002 entry).  Conditions in the past may have been even more conducive to their rapid growth.    Like Ian, we should all look woodward and marvel at the trees.  Look at a tall tree nearby, whether an oak, a pine, or whatever is prominent in your neck of the woods.  Imagine if it were the only tree on earth.  Would it not be an international tourist attraction?  People would travel the world over to look at this natural marvel.  They would wonder how it could pump water from under the ground all the way up to the highest leaves.  They would admire its beauty.  It would seem almost a miracle.  The fact that trees are so plentiful should not blind us to the reality that trees indeed are some of the most elegant, handsome, remarkable, and complex entities in all of creation.  Why not take the family on a hike or picnic under the shady trees, and use it as a teachable moment?Enjoy this gallery of the natural water pumps that enrich our world: by a lake (foxtail pine), in a canyon (cottonwood), outdoor pews (sequoia), blooms in fog (dogwood), giant’s foot (sequoia), forest blanket (lodgepole pine), Yosemite valley (pine, oak), Tehipite valley (pine, oak), redwood saddle (sequoia), mountain majesty (pine), waterfall curtain (cottonwood), giant and dwarves (sequoia).(Visited 15 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more


More Impacts on Crater Count Dating

December 19, 2019

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first_imgPlanetary scientists have relied on crater counts to estimate the surface age of a planet or moon.  The more craters, the older the surface.  This method has recently come under closer scrutiny (see 10/20/2005) because of the phenomenon of secondary cratering.    A simplistic look at a crater-scarred planet or moon might lead one to assume a ratio of one impactor to one crater.  Planetary scientists have been realizing, however, that a big enough rock can produce many craters.  Another paper on this subject was published in Icarus this month.1  A team of Russian and American planetologists announced three findings from studies of Mars:Small clusters:  Some impactors break up in the atmosphere and produce small clusters of craters 100 to 300 meters wide, each pockmark a few tens of meters in diameter.  The breakup of weak cometary bodies on entry through the Martian atmosphere could be responsible for some of these small clusters.Large clusters:  The team identified a second population of larger clusters, distinct from the small clusters.  Their models indicated that one giant impact can launch numerous fragments as big as hundreds of meters across.  Some fragments can be ejected above escape velocity, but many will remain and fall back to the planet.  On Mars, the weakened fragments tend to break up in the atmosphere into sizes 5 to 50 meters, which is why clusters with similar size distributions are not seen on our airless moon.    Secondaries can often be identified along rays from the primary crater, but not always.  The fragments can travel long distances, flying through the atmosphere for more than an hour, “making it difficult to identify the parent crater.”  The authors explained that for fragments ejected from a primary impact, “launch at 3 km/s can distribute fragments over much of a hemisphere, and launch at 4 km/s can distribute fragments over most of Mars….”  Escape velocity on Mars is 5 km/s.Martian meteorites:  The meteorites found on Earth that originated on Mars appear to require impactors 3-7 km across.  An impactor hitting at an oblique angle can produce jets nearly parallel to the surface capable of accelerating surface rocks to escape velocity.  This implies that many other fragments fail to escape.  “Clearly, if fragmenting debris is lofted to escape velocity in order to produce martian meteorites … on Earth, then other debris is lofted to barely suborbital speeds and secondary impact pits must exist not just in near-primary swarms, but also in near-random positions scattered around Mars.”The authors did not comment specifically on the implications of their findings on the crater-count dating method.  They worked within the standard Martian timescale with its three periods, Noachian (3.8 to 3.5 billion years ago),2 Hesperian (3.5 to 1.8 billion years ago) and Amazonian (1.8 billion years to the present): e.g., “We conclude that most of the clusters discussed here probably formed in the last half of martian time, not during the Noachian era.  For this reason, we suspect they formed under essentially present-day, low-pressure atmospheric conditions.”  The degree of uncertainty in dating the clusters, however, was evident in the following paragraph:Further constraints are possible, from crater formation rate information.  Barlow and Osborne (2001) find most clusters on Noachian and Hesperian terrain, but some of our clusters, such as the one on Meridiani Planum (Fig.  4) and others on Olympus Mons, are found on geologically young surfaces.  This implies cluster formation within the last few hundred Myr, possibly within the last 20 Myr in the case of the sparsely cratered surface of Meridiani Planum, which may have been exhumed within the last tens of Myr (based on paucity of small sharp craters; [Hartmann et al., 2001] and [Hartmann, 2005]).  These results suggest clusters accumulating on surfaces throughout martian history.  Note that it is plausible that many young clusters on Mars might be products of a single large impact.Yet could these age estimates themselves be undermined by the findings of the paper?  If crater-counting methods were used in establishing the commonly-accepted geological periods, how can they be considered reliable now, considering that a single large impact can produce secondaries at random locations across the whole planet?    The authors hinted at the only logical answer to these questions after discussing various models for the fragmentation of incoming bodies: “All these assumptions suffer from limitations.”  Later, “Precise numbers of craters, their sizes and displacement are dependent on assumptions used,” they said.  As a matter of fact, the words assume and assumption appeared 19 times in the paper.1Popova, Hartmann, Nemtchinov, Richardson and Berman, “Crater clusters on Mars: Shedding light on martian ejecta launch conditions,” Icarus Volume 190, Issue 1, September 2007, Pages 50-73, doi:10.1016/j.icarus.2007.02.022.2The Noachian epoch, after the prominent Martian region Noachis Terra (which means “Land of Noah”) was named because of the presumption that Mars was warm and wet early in its history.  This assumption was called into question last week (see 09/24/2007, bullet 2).Despite their rigorous and admirable work of calculating and estimating the physical effects of impacting bodies on Mars, the authors could not think outside the box.  Their own work casts severe doubt on the ability to use crater counts as a dating method.  In principle, if one impact can produce ten million secondaries scattered around the whole planet (see 10/20/2005), there is no way to know how old the Martian surface is.  If anything, one would think the whole planet would have been saturated with craters in short order, hinting that the surface might be young.  And think about it: we’ve already seen several global dust storms in the 33 years since the first Martian orbiter.  How much weathering of craters would be expected in tens of millions of years?  And why is bedrock still clean-swept in large areas on Mars? (06/01/2005).    Because these scientists began their modeling with undaunted faith in the Age of the Solar System (A.S.S.), a figure (4.5 billion years) that, according to the Law of the Needs of the Darwins cannot be altered, they had to make it all work within their mythical paradigm.  Their crater cluster formation model must fit within the scheme of imaginary Noachian, Hesperian and Amazonian epochs, even though their own work undermines the assumptions that went into making the scheme in the first place (for other problems with the current scheme, see Astrobiology Magazine).  What’s in a name?  Would calling them the Washingtonian, Lincolnian and Clintonian epochs make Mars blink an eye?  Let the discerning mind understand that the fancy charts of geological time scales on Mars and Earth are human impositions on the data – not inevitable products of the observations themselves.(Visited 18 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img read more


Bing According to Microsoft: Unique Visits Up 8% in June

December 17, 2019

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first_imgA Web Developer’s New Best Friend is the AI Wai… frederic lardinois Tags:#Microsoft#news#NYT#search#web Why Tech Companies Need Simpler Terms of Servic… Related Posts center_img We already knew that Bing, Microsoft’s new search engine was doing quite well, but today, Microsoft released its own data about the state of the service. Bing launched just a bit more than one month ago, and since then, we have seen reports from numerous third-party web analytics firms that Bing was indeed doing quite well. According to Microsoft’s own data, Bing saw an 8% growth in unique users in June compared to the previous month. The company also noted that the number of users who would be “likely to recommend” Bing to others doubled in June. Shopping and TravelIn addition, Microsoft also announced that Bing Shopping saw a 300% increase in visits and Bing Travel saw its traffic grow by 90% month to month (though Bing Travel’s image is a bit tarnished by a recent controversy about its design). Source: StatCounter Global Stats – Search Engine Market ShareAdvertisersOverall, the numbers Microsoft cites for Bing’s traffic compare well with data we have seen from various web analytics firms, so we have little reason to believe that Microsoft doctored them (though the latest data from Compete is slightly less encouraging for Bing). Microsoft, however, also detailed some data about the results advertisers are seeing on Bing, though we will have to withhold judgment here. It is hard to find hard data about this, and while Microsoft announced that TigerDirect saw its sales and order volume triple, and its conversion rates and average order size “increase significantly,” we just don’t know if this was a special case or something advertisers saw across the board.DevelopersAccording to Microsoft, developers are also taking a liking to the Bing API. The number of registered developers doubled last month, and incoming API requests are up 50% since launch.What’s Next?While Microsoft didn’t specify any exact numbers, the fact that far more users are likely to recommend Bing than they were likely to recommend Live Search must be an encouraging sign for the company. Microsoft didn’t specify any future plans in today’s post, but we know that Microsoft’s biggest challenge is to overcome Google’s momentum and to keep users on its service and from switching back to Google. 8 Best WordPress Hosting Solutions on the Market Top Reasons to Go With Managed WordPress Hostinglast_img read more


Zeke Responds To Criticism: “I Guess I’m The Big Bad Wolf Now”

October 27, 2019

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first_imgFollowing Ohio State’s loss to Michigan State on Saturday night, Buckeyes running back Ezekiel Elliott made some headlines after criticizing his coaching staff for its play-calling against the Spartans. Since, he’s been receiving a great deal of criticism – many have even suggested that he be benched for the team’s game against Michigan this Saturday.Well, Zeke has responded on Twitter. First, he retweeted a number of quotes that reflect his interview in a more positive light. He then joked that he’s now the “big bad wolf.” Clearly, he thinks he’s being treated a bit unfairly.ezekiel elliott tweets after postgame interviewI guess I’m the big bad wolf now lol— EzekielElliott#⃣1⃣5⃣ (@EzekielElliott) November 22, 2015Ohio State head coach Urban Meyer hasn’t addressed Elliott’s comments yet – but we imagine he will during his weekly press conference Monday. We’ll find out then if there will be any punishment.last_img read more


The Thursday news briefing An ataglance survey of some top stories

October 17, 2019

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first_imgHighlights from the news file for Thursday, Dec. 21———MEMORIAL HELD FOR SHERMANS: Thousands of people attended a memorial on Thursday for billionaire philanthropists Barry and Honey Sherman, who were found dead in their Toronto home nearly a week ago. The Shermans’ children say coping with the speculation surrounding their parents’ deaths has compounded the pain of losing their parents. Police have said the Shermans died of “ligature neck compression” and have called the deaths suspicious. The Shermans’ son Jonathon says it has all been a terrible, shocking adjustment.———OPPOSITION WANT TRUDEAU TO REPAY SOME CHRISTMAS VACATION COSTS: The Opposition parties say Prime Minister Justin Trudeau should repay all or part of the transportation and security costs for a Christmas vacation to the Aga Khan’s private Bahamian island last year. The trip cost taxpayers more than $200,000. Ethics commissioner Mary Dawson found the prime minister violated four different provisions of the Conflict of Interest Act. The Tories and New Democrats say Trudeau owes it to taxpayers to repay the bill. The Prime Minister’s Office says Trudeau paid the cost of his and his family’s flights to and from Nassau but would not disclose the precise tab.———MAN FOUND GUILTY OF KILLING NOVA SCOTIA POLICE OFFICER: A Halifax jury has found a man guilty of punching and strangling Nova Scotia police officer Catherine Campbell. The jury rejected Christopher Garnier’s claim that the off-duty officer died accidentally during rough sex. Garnier was convicted of second degree murder, which comes with an automatic life sentence. A hearing to determine Garnier’s parole eligibility is scheduled for May.———HELICOPTER CRASH MAY HAVE BEEN CAUSED BY LOOSE TOOL BAG: The Transportation Safety Board says it appears that an improperly secured tool bag hit the rear rotor of a helicopter that subsequently crashed in eastern Ontario last week. The board says its preliminary investigation into the crash suggested the tool kit carried on a platform outside the helicopter owned by electrical utility Hydro One was the main cause of the deadly incident.———CANADA AVOIDS CRITICIZING TRUMP OVER EMBASSY MOVE: Canada abstained from a vote in the United Nations that criticized U.S. President Donald Trump for his decision to move the U.S. embassy from Tel Aviv to Jerusalem. The UN voted 128-9 in favour of a resolution declaring the U.S. president’s recognition of Jerusalem as the Israeli capital to be null and void. Canada was among the 35 countries that abstained. Canada was left in a difficult position because Trump had threatened to retaliate against countries that supported the resolution.———COUGAR HUNTING IN ALBERTA POPULAR, BIOLOGIST SAYS: A wildlife biologist says cougar hunting is not only legal but quite popular in Alberta during the late fall and early winter. Mark Boyce of the University of Alberta says there are at least 2,500 cougars in the province. He says there is an annual quota of up to 155 cougars that can be killed by residents each winter season in Alberta. Another 30 cats can be hunted by non-residents. The issue surfaced after an Alberta-based host of an outdoor TV show triggered outrage online when he bragged about hunting a big cat earlier this month.———FIRST NATIONS ELDER CRITICAL OF CANADIAN TIRE SEARCH: The family of a First Nations elder says he was humiliated when a Canadian Tire employee in Saskatchewan stopped him and searched him this week. Gordon Albert of the Sweetgrass First Nation was in North Battleford shopping for a gift with his family. Albert’s wife Marlene says an anti-theft device at the door beeped as they left and Albert was searched. The store manager denied race had anything to do what happened but Albert’s son disagrees.———FORMER MONTREAL CONDUCTOR ACCUSED OF SEXUAL ASSAULT: Four performers say renowned conductor Charles Dutoit sexually assaulted them, telling The Associated Press he physically restrained them, forced his body against theirs and caused other non-consensual contact. The Swiss-born maestro has not responded to multiple efforts to contact him. The performers — three opera singers and a classical musician — contend the attacks took place between 1985 and 2010 in five different cities in the U.S. Dutoit, who had a 25-year run with the Montreal Symphony Orchestra, did not immediately respond to multiple attempts by the AP to reach him.———last_img read more


Private Schools Opened in Turks Caicos

September 17, 2019

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first_imgFacebook Twitter Google+LinkedInPinterestWhatsApp TCI Premier blasts Opposition side for “slop” information, sets it straight in HOA Recommended for you Premier attends town hall meetings Related Items:akierra missick, sharlene cartwright-robinson, tci private schools, turks caicos schools Facebook Twitter Google+LinkedInPinterestWhatsAppFreshly dressed and fresh faced! Many of our children head back to school today… as a lot of the private schools will open. The Official Opposition Leader, Hon Sharlene Robinson with these words on day one of the 2014-2015 academic year: “Each year, you are forced to deal with less than stellar conditions but time and time again you rise to the occasion. I pause to congratulate… Stay focused; stay committed.” The 14 government schools are delayed opening a week, announced by Education Minister & Deputy Premier Akierra Missick in the House of Assembly last Thursday; TS Cristobal impacted the rush to prepare those campuses. Attorney calls on UWI to honor TCI leaderslast_img read more


Hurricane Jose Advisory Number 22

September 17, 2019

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first_imgFacebook Twitter Google+LinkedInPinterestWhatsApp Facebook Twitter Google+LinkedInPinterestWhatsAppUnited States, September 10, 2017 – Miami, FL – JOSE BEGINNING TO WEAKEN AS IT CONTINUES NORTHWEST….At 500 PM AST (2100 UTC), the center of Hurricane Jose was located near latitude 22.8 North, longitude 66.9 West.   Jose is moving toward the northwest near 16 mph (26 km/h). This motion is expected to continue tonight with a slowing of forward speed on Monday.Jose will begin turning toward the northeast Monday night, followed by a more eastward motion on Tuesday.   On the forecast track, Jose will remain well to the east of the Bahamas for the next couple of days.  Maximum sustained winds have decreased to near 120 mph (195 km/h) with higher gusts.Jose is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale.    Additional weakening is forecast, but Jose is forecast to remain a hurricane during the next couple of days.Hurricane-force winds extend outward up to 40 miles (65 km) from the center and tropical-storm-force winds extend outward up to 160 miles (260 km).  The estimated minimum central pressure is 956 mb (28.23 inches).HAZARDS AFFECTING LANDSURF:  Swells generated by Jose are affecting portions of the northern coast of Puerto Rico, and will begin to affect Hispaniola, portions of the Bahamas, and the Turks and Caicos Islands over the next couple of days.   These swells are likely to produce high surf and rip current conditions. Please consult products from your local weather office. Related Items:last_img read more


School District Requests Additional Funding From Borough

September 14, 2019

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Is Jet Airways headed for Kingfishers fate Fact file on Naresh Goyal

September 5, 2019

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Simons algorithm run on quantum computer for the first time—faster than on

August 31, 2019

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first_img D-Wave and predecessors: From simulated to quantum annealing Experimental setup. Credit: arXiv:1410.3859 [quant-ph] Citation: Simon’s algorithm run on quantum computer for the first time—faster than on standard computer (2014, November 17) retrieved 18 August 2019 from https://phys.org/news/2014-11-simon-algorithm-quantum-timefaster-standard.html A quantum computer is a computing device that relies on quantum bits (qubits) rather than the standard digital bits that have been used by most every computing device made. It’s believed that such a computer would be able to run certain algorithms faster or more efficiently than standard computers due to their ability to take advantage of quantum mechanics properties such as entanglement and superposition. Until now, however, it’s not been possible to run algorithms created specifically for such machines, to test out this theory.In this new effort, the team ran what is known as Simon’s algorithm, for Daniel Simon, who, twenty years ago, came up with an algorithm designed specifically to run faster on a quantum computer than it would, on a standard computer. Its purpose is to figure out whether a black box returns a unique output for every possible input. The team ran the simplest version of the algorithm on a quantum computer that used just six qubits, and report that it took just two iterations to solve the problem, where it would take a normal computer three. That may not seem like much, but it is believed that as more qubits are added, the larger the difference would be between the two approaches, which means, the quantum computer would be able to solve the algorithm much faster, or technically, more efficiently than standard computers. That’s the good news. The bad news is that thus far, there is no practical benefit to running Simon’s algorithm—its sole purpose is to show that for one algorithm, the quantum computer does better.But that’s not the end of the story, showing that one such algorithm can return a result more quickly on a quantum computer offers researchers hope that other algorithms, such as Shor’s algorithm (which can be used to factor large numbers into their primes—an important part of encryption schemes) could be run much faster as well. © 2014 Phys.org Explore further More information: Experimental Realization of a One-Way Quantum Computer Algorithm Solving Simon’s Problem, Phys. Rev. Lett. 113, 200501 – Published 11 November 2014 dx.doi.org/10.1103/PhysRevLett.113.200501 . On Arxiv: arxiv.org/abs/1410.3859ABSTRACTWe report an experimental demonstration of a one-way implementation of a quantum algorithm solving Simon’s problem—a black-box period-finding problem that has an exponential gap between the classical and quantum runtime. Using an all-optical setup and modifying the bases of single-qubit measurements on a five-qubit cluster state, key representative functions of the logical two-qubit version’s black box can be queried and solved. To the best of our knowledge, this work represents the first experimental realization of the quantum algorithm solving Simon’s problem. The experimental results are in excellent agreement with the theoretical model, demonstrating the successful performance of the algorithm. With a view to scaling up to larger numbers of qubits, we analyze the resource requirements for an n-qubit version. This work helps highlight how one-way quantum computing provides a practical route to experimentally investigating the quantum-classical gap in the query complexity model. , arXiv (Phys.org) —A team of researchers working in South Africa has reported that they’ve successfully run Simon’s algorithm on a quantum computer for the first time. In their paper published in Physical Review Letters, the team describes how they ran the algorithm, the results they found and what doing so means for the future of quantum computing. Journal information: Physical Review Letters 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