Foundational Concept of Ecology Tested: Purple Loosestrife Altered Life in Nearby Ponds
ScienceDaily (June 23, 2012) —An elementary school science activity asks children who have each been assigned a wetland plant or animal to connect themselves with string and tape to other "organisms" their assigned plant or animal interacts with in some way.
Male blue dasher (Pachydiplax longipennis), is one of about 10 dragonfly species commonly seen buzzing the artificial pond systems at the Tyson Research Center, WUSTL’s field station for ecosystem studies. A new study showed that the dragonflies were the liaisons that connected aquatic to terrestrial ecosystems, allowing the plant purple loosestrife to “tug” on the interconnections between organisms in both ecosystems. (Credit: Travis Mohrman/Tyson Research Center)
Once an ecosystem web has been created, the teacher describes an event that affects one "organism." That "organism" tugs on its string. Other "organisms" that feel the tug then tug on their strings in turn.
The lesson is that every organism is important to the health and balance of a wetland and that every organism in the wetland is connected to every other organism in some way.
That's more or less an article of faith among ecologists, but how true is it really? Ecologists rarely have the time or resources to test this foundational concept through experiment.
Now a summer-long study shows that the flowering invasive plant purple loosestrife (Lythrum salicaria) triggers a chain of interactions that ultimately alters the diversity of zooplankton populations in artificial ponds.
The interactions cross traditional ecosystem boundaries, connecting aquatic to terrestrial systems on the wings of dragonflies that exploit, at different times in their lives, the resources of both the water and the land.
"It's easy to say that everything is connected in some way, but how much these connections matter is something that we don't always know," says Kevin G. Smith, PhD, adjunct professor of biology in Arts & Sciences at Washington University in St. Louis and associate director of the Tyson Research Center, WUSTL's 2,000-acre field station.
By verifying one of the foundational ideas of ecology, the experiment, published electronically May 24 by the journal Oecologia in advance of print, will help inform decisions about biological control of invasive species, restoration of degraded habitats and similar ecological issues.
A study long meditated
Smith says the experiment was inspired by work his colleague Tiffany Knight published in 2005. Knight, PhD, associate professor of biology at WUSTL, had showed that plants do better if they are near ponds with fish, because the fish eat dragonfly larvae, reducing the population of dragonflies that prey on plant pollinators.
Smith was intrigued by the study because the effect was indirect and cut across ecosystems as traditionally defined. "Ecologists tend to study forests, or ponds, or glades, but there is a lot of border crossing going on," he says, "and Tiffany's study demonstrated that."
His idea was to see if he could find links that went the other way, connecting land to water instead of water to land. If fish affected land plants, could plants affect fish -- or at any rate aquatic communities?
One plant that might tug hard on ecosystem connections, Smith thought, was the purple loosestrife, which produces many showy flowers and displaces native plants such as cattails that produce few or none.
"The flowers make it functionally different from the native plants," Smith says, "so it seemed possible its presence would cause a disturbance that would ripple through the wetland communities."
But it took a few years for Smith to start the experiment.
"Everybody I talked to about it thought that one of the links would fail; that it wasn't possible for every connection from the plant to the aquatic system to hold as I had hypothesized it would," Smith says. "I sort of felt that way, too. It seemed like a long shot."
Eight artificial wetlands
But the tradition at Tyson Research Center is to challenge fundamental ecological ideas with the methods and tools of science, and so in the summer of 2009, Smith finally undertook what he knew would be a labor-intensive experiment.
He and colleagues Laura A. Burkle, PhD, then a postdoctoral fellow who is now a faculty member at Montana State University, and Joseph R. Mihaljevic, then a WUSTL undergraduate and now a graduate student at the University of Colorado, Boulder, created eight artificial wetlands at Tyson, each consisting of a central stock tank and four smaller surrounding pools.
The tanks were stocked with six species of aquatic plants and three species of snails and inoculated with the smaller zooplankton and phytoplankton drawn from local ponds. The remainder of the aquatic community, such as frogs, dragonflies, flies, beetles and bugs, was allowed to assemble naturally.
Loosestrife plants in pots were placed in each of the four small pools. The pools were separated from the tanks so that only the flowers -- and notplant litter and pollen -- would play a role in the ecosystem of the central pool.
The eight "wetlands" thus created were divided into four treatment groups and the number of loosestrife flowers in each "wetland" was manipulated to mimic differences in loosestrife density.
The loosestrife in two wetlands were left alone but flowers at the other wetlands were picked to reduce their numbers to 75 percent, 50 percent or 25 percent of the flowers at the untouched wetlands.
During the course of the experiment, the small insects visiting the pools were regularly counted and categorized, as were the dragonflies and their behaviors.
At the end of the summer and the experiment, the zooplankton and phytoplankton in the eight central tanks were sampled and identified.
The scientists were able to track the effect of the loosestrife flowers across four trophic levels, or levels in the food web, and two ecosystems, the terrestrial and the aquatic ones.
The links worked as follows: Wetlands with abundant flowers attracted more pollinating insects; the insects in turn attracted more of the carnivorous dragonflies; the well-nourished dragonflies laid more eggs in the central ponds; the voracious dragonfly larvae that hatched from the eggs altered the diversity of the zooplankton communities in the ponds.
In an unexpected turn, flowering loosestrife actually increased zooplankton species richness, perhaps, speculates Smith, because they preferentially ate a dominant zooplankton species, releasing others from competition.
"To be honest," Smith says, "although the increase in zooplankton diversity is interesting and surprising, I don't think that specific detail matters too much. Nor, is the point simply that purple loosestrife might be affecting aquatic ecosystems, although that is important from a management perspective.
"What matters is that we showed the interconnections are actually strong enough to transmit disturbances through and across webs. We pushed on one link and something four links away in another ecosystem moved.
http://www.sciencedaily.com/releases/20 ... 094322.htm
The second-rate mind is only happy when it is thinking with the minority.
The first-rate mind is only happy when it is thinking."
A. A. Milne
Tevatron Scientists Announce Their Final Results On the Higgs Particle
ScienceDaily (July 2, 2012) — After more than 10 years of gathering and analyzing data produced by the U.S. Department of Energy's Tevatron collider, scientists from the CDF and DZero collaborations have found their strongest indication to date for the long-sought Higgs particle. Squeezing the last bit of information out of 500 trillion collisions produced by the Tevatron for each experiment since March 2001, the final analysis of the data does not settle the question of whether the Higgs particle exists, but gets closer to an answer.
After more than 10 years of gathering and analyzing data produced by the U.S. Department of Energy’s Tevatron collider, scientists from the CDF and DZero experiments have found their strongest indication to date for the long-sought Higgs particle. The Tevatron results indicate that the Higgs particle, if it exists, has a mass between 115 and 135 GeV/c2, or about 130 times the mass of the proton. (Credit: Image courtesy of Fermilab)
The Tevatron scientists unveiled their latest results on July 2, two days before the highly anticipated announcement of the latest Higgs-search results from the Large Hadron Collider in Europe.
"The Tevatron experiments accomplished the goals that we had set with this data sample," said Fermilab's Rob Roser, cospokesperson for the CDF experiment at DOE's Fermi National Accelerator Laboratory. "Our data strongly point toward the existence of the Higgs boson, but it will take results from the experiments at the Large Hadron Collider in Europe to establish a discovery."
Scientists of the CDF and DZero collider experiments at the Tevatron received a round of rousing applause from hundreds of colleagues when they presented their results at a scientific seminar at Fermilab. The Large Hadron Collider results will be announced at a scientific seminar at 2 a.m. CDT on July 4 at the CERN particle physics laboratory in Geneva, Switzerland.
"It is a real cliffhanger," said DZero co-spokesperson Gregorio Bernardi, physicist at the Laboratory of Nuclear and High Energy Physics, or LPNHE, at the University of Paris VI & VII. "We know exactly what signal we are looking for in our data, and we see strong indications of the production and decay of Higgs bosons in a crucial decay mode with a pair of bottom quarks, which is difficult to observe at the LHC. We are very excited about it."
The Higgs particle is named after Scottish physicist Peter Higgs, who among other physicists in the 1960s helped develop the theoretical model that explains why some particles have mass and others don't, a major step toward understanding the origin of mass. The model predicts the existence of a new particle, which has eluded experimental detection ever since. Only high-energy particle colliders such as the Tevatron, which was shut down in September 2011, and the Large Hadron Collider, which produced its first collisions in November 2009, have the chance to produce the Higgs particle. About 1,700 scientists from U.S. institutions, including Fermilab, are working on the LHC experiments.
The Tevatron results indicate that the Higgs particle, if it exists, has a mass between 115 and 135 GeV/c2, or about 130 times the mass of the proton.
"During its life, the Tevatron must have produced thousands of Higgs particles, if they actually exist, and it's up to us to try to find them in the data we have collected," said Luciano Ristori, co-spokesperson of the CDF experiment and physicist at Fermilab and the Italian Istituto Nazionale di Fisica Nucleare (INFN) . "We have developed sophisticated simulation and analysis programs to identify Higgs-like patterns. Still, it is easier to look for a friend's face in a sports stadium filled with 100,000 people than to search for a Higgs-like event among trillions of collisions."
The final Tevatron results corroborate the Higgs search results that scientists from the Tevatron and the LHC presented at physics conferences in March 2012.
The search for the Higgs particle at the Tevatron focuses on a different decay mode than the search at the LHC. According to the theoretical framework known as the Standard Model of Particles, Higgs bosons can decay in many different ways. Just as a vending machine might return the same amount of change using different combinations of coins, the Higgs can decay into different combinations of particles. At the LHC, the experiments can most easily observe the existence of a Higgs particle by searching for its decay into two energetic photons. At the Tevatron, experiments most easily see the decay of a Higgs particle into a pair of bottom quarks.
Tevatron scientists found that the observed Higgs signal in the combined CDF and DZero data in the bottom-quark decay mode has a statistical significance of 2.9 sigma. This means there is only a 1-in-550 chance that the signal is due to a statistical fluctuation.
"We achieved a critical step in the search for the Higgs boson," said Dmitri Denisov, DZero cospokesperson and physicist at Fermilab. "While 5-sigma significance is required for a discovery, it seems unlikely that the Tevatron collisions mimicked a Higgs signal. Nobody expected the Tevatron to get this far when it was built in the 1980s."
The Tevatron is one of eight particle accelerators and storage rings on the Fermilab site. The largest, operational accelerator at Fermilab now is the 2-mile-circumference Main Injector, which provides particles for the laboratory's neutrino and muon research programs.
The CDF and DZero collaborations submitted their joint Higgs search results to the electronic preprint archive arXiv.org. The paper also is available at: http://tevnphwg.fnal.gov/results/SM_Higgs_Summer_12/
http://www.sciencedaily.com/releases/20 ... 141716.htm
Not a whole lot new, Mainly a link to watch said conference tomorrow.
http://www.livescience.com/21339-higgs- ... sults.html
Physicists Get Closer Than Ever to Higgs Particle
Clara Moskowitz, LiveScience Senior Writer
Date: 02 July 2012 Time: 02:08 PM ET
American scientists have found strong hints that the rumored Higgs boson particle exists, and has been created inside an atom smasher in Illinois.
The news comes just days before big news on the search for the Higgs is expected to be delivered by physicists from the world's largest particle accelerator, the Large Hadron Collider (LHC).
"This is a very exciting week — it may be the most exciting week in physics since I became a physicist," Joe Lykken, a theoretical physicist at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Ill., said during a news conference today (July 2).
The Higgs boson, also called the "God particle," is thought to explain why other particles have mass. The idea is that a related energy field, called the Higgs field, permeates space, and that as particles pass through this field their interactions with it confer mass on them, like a spoon being dragged through molasses. [Top 5 Implications of Finding the Higgs Boson]
Fermilab scientists announced today that they've narrowed down the possible range of masses the Higgs particle can have, if it exists, to between 115 and 135 gigaelectron volts (GeV), a unit roughly equivalent to the mass of a proton. The findings are the result of a long and thorough analysis of particle collisions inside Fermilab's Tevatron accelerator. The machine, the biggest atom smasher in the United States, was shut down in 2011, but scientists are still poring through its measurements.
Now the Tevatron has been eclipsed by the larger and more powerful LHC, a17-mile (27 kilometer) underground loop beneath Switzerland and France. LHC scientists are due to announce the latest results from their search for the Higgs on July 4 at the International Conference on High Energy Physics in Melbourne, Australia.
Scientists have hinted that the LHC has come close to finding the Higgs boson, but that they aren't quite ready to announce its discovery.
"I know that 2012 is the year; I can't tell you that July is the month," said Tom LeCompte, a physicist at Illinois' Argonne National Laboratory, and a member of LHC's ATLAS experiment.
Last December, LHC scientists announced that they'd seen hints of what could be the Higgs boson in an excess of particles weighing around 124 or 125 GeV. Yet the researchers hadn't collected enough data to say for sure if the blip represented the Higgs particle or if the pattern could have been a statistical fluke.
To claim a true discovery in science, physicists wait until their statistics reach the level of "five sigma," meaning there is a one in 3.5 million chance the signal isn't real.
Currently, the Tevatron results suggest the existence of the Higgs, but aren't quite that certain.
"We're close to 3 sigma," said Fermilab research Rob Roser, a cospokesperson for Tevatron's CDF experiment."What that means is I'd be willing to bet your house, but not mine. At 5 sigmas, I'll bet my own house."
Still, the Fermilab team's findings are enough to qualify as the strongest claim to date for the existence of the Higgs. While the LHC was able to reduce the possible mass range for the particle to an even narrower window, it did so with less certainty.
However, that could change come Wednesday.
The LHC results will be announced July 4 at 3 a.m. EDT (9 a.m. CEST), and will be webcast live here: http://webcast.web.cern.ch/webcast
"The Heaven's Lights are fed by the energy generated inside the furnaces of Hell; I AM One Conductive Wire! "
here is the last lecture that he made at mit
after a sweat hog feminazi lured him onto a
on line affair and then trashed his name
the misandrist must end badly
“Mediocrity is self-inflicted and genius is self-bestowed."
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