Small but speedy: Short plants live in the evolutionary fast lane

Public release date: 21-May-2013
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Contact: Robert Lanfear
rob.lanfear@anu.edu.au
National Evolutionary Synthesis Center (NESCent)

Durham, NC Biologists have known for a long time that some creatures evolve more quickly than others. Exactly why isn't well understood, particularly for plants. But it may be that height plays a role, says Robert Lanfear of Australian National University and the U. S. National Evolutionary Synthesis Center.

In a study to be published 21 May in the journal Nature Communications, Lanfear and colleagues report that shorter plants have faster-changing genomes.

Drawing from a database of global patterns in plant height for more than 20,000 species, the researchers estimated average maximum height for nearly 140 plant families worldwide ranging from a group of tropical plants called the Burmanniaceae, whose average height tops out at two inches (5 cm), to a family called the Tetramelaceae, which can tower above 140 feet (45 m).

For each family, the researchers also estimated how much their DNA sequences the strings of As, Cs, Ts and Gs that make up their genetic code changed over time.

When they plotted evolutionary rates against plant height, the researchers were surprised to find that shorter plants evolved as much as five times faster than taller ones.

The pattern held up for both the nuclear and the chloroplast genomes, even after the researchers accounted for factors shown in previous studies to correlate with evolutionary speed such as species richness, latitude, temperature, and levels of UV radiation. The results also held up when the researchers looked just within trees and shrubs, which are typically tall, or just herbs, which tend to be short.

What puts short plants in the evolutionary fast lane? The researchers suspect the difference may be driven by genetic changes that accumulate in the actively-dividing cells in the tip of the plant shoot as it grows. Cells don't copy their DNA perfectly each time they divide. In animals, most DNA copy mistakes that occur in the cells of the animal's body can't be inherited they're evolutionary dead ends. But this isn't the case for plants, where genetic changes in any part of the plant could potentially get passed on if those cells eventually form flowers or other reproductive organs

"Genetic changes that occur during cell division in plant shoots could potentially get passed on to future generations," Lanfear explained.

Importantly, growth slows as plants increase in size, he added. This means that over the long term, the rate of cell division and genome copying in taller plants eventually slows down, and changes in DNA the raw material for evolution accumulates less quickly.

"Our study also answers a question that was posed [in a paper] in Nature in 1986:" the researchers write. "Do plants evolve differently? The answer is 'yes.'"

###

The other authors of this study were Simon Ho of the University of Sydney, T. Jonathan Davies of McGill University, Angela Moles of the University of New South Wales, Lonnie Aarssen of Queen's University, Nathan Swenson of Michigan State University, Laura Warman of the USDA Forest Service, Amy Zanne of George Washington University and Andrew Allen of Macquarie University in Australia.

CITATION: Lanfear, R., et al. (2013). "Taller plants have lower rates of molecular evolution: the rate of mitosis hypothesis." Nature Communications.

All data, code and scripts used in this study are available in the Dryad Digital Repository at http://dx.doi.org/dryad.43mg3

The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit http://www.nescent.org.

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Public release date: 21-May-2013
[ | E-mail | Share ]

Contact: Robert Lanfear
rob.lanfear@anu.edu.au
National Evolutionary Synthesis Center (NESCent)

Durham, NC Biologists have known for a long time that some creatures evolve more quickly than others. Exactly why isn't well understood, particularly for plants. But it may be that height plays a role, says Robert Lanfear of Australian National University and the U. S. National Evolutionary Synthesis Center.

In a study to be published 21 May in the journal Nature Communications, Lanfear and colleagues report that shorter plants have faster-changing genomes.

Drawing from a database of global patterns in plant height for more than 20,000 species, the researchers estimated average maximum height for nearly 140 plant families worldwide ranging from a group of tropical plants called the Burmanniaceae, whose average height tops out at two inches (5 cm), to a family called the Tetramelaceae, which can tower above 140 feet (45 m).

For each family, the researchers also estimated how much their DNA sequences the strings of As, Cs, Ts and Gs that make up their genetic code changed over time.

When they plotted evolutionary rates against plant height, the researchers were surprised to find that shorter plants evolved as much as five times faster than taller ones.

The pattern held up for both the nuclear and the chloroplast genomes, even after the researchers accounted for factors shown in previous studies to correlate with evolutionary speed such as species richness, latitude, temperature, and levels of UV radiation. The results also held up when the researchers looked just within trees and shrubs, which are typically tall, or just herbs, which tend to be short.

What puts short plants in the evolutionary fast lane? The researchers suspect the difference may be driven by genetic changes that accumulate in the actively-dividing cells in the tip of the plant shoot as it grows. Cells don't copy their DNA perfectly each time they divide. In animals, most DNA copy mistakes that occur in the cells of the animal's body can't be inherited they're evolutionary dead ends. But this isn't the case for plants, where genetic changes in any part of the plant could potentially get passed on if those cells eventually form flowers or other reproductive organs

"Genetic changes that occur during cell division in plant shoots could potentially get passed on to future generations," Lanfear explained.

Importantly, growth slows as plants increase in size, he added. This means that over the long term, the rate of cell division and genome copying in taller plants eventually slows down, and changes in DNA the raw material for evolution accumulates less quickly.

"Our study also answers a question that was posed [in a paper] in Nature in 1986:" the researchers write. "Do plants evolve differently? The answer is 'yes.'"

###

The other authors of this study were Simon Ho of the University of Sydney, T. Jonathan Davies of McGill University, Angela Moles of the University of New South Wales, Lonnie Aarssen of Queen's University, Nathan Swenson of Michigan State University, Laura Warman of the USDA Forest Service, Amy Zanne of George Washington University and Andrew Allen of Macquarie University in Australia.

CITATION: Lanfear, R., et al. (2013). "Taller plants have lower rates of molecular evolution: the rate of mitosis hypothesis." Nature Communications.

All data, code and scripts used in this study are available in the Dryad Digital Repository at http://dx.doi.org/dryad.43mg3

The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit http://www.nescent.org.

---

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Source: http://www.eurekalert.org/pub_releases/2013-05/nesc-sbs051513.php

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Czech president in dispute over gay rights

PRAGUE (AP) ? The Czech Republic's controversy-courting new president is under fire for refusing to grant a university professorship to one of his critics and hinting that it is because the man is a gay rights activist.

In what is normally a formality, Czech presidents appoint the country's professors after they are nominated for the top title by their universities, but left-leaning President Milos Zeman has stood firm by his decision not to let a prominent literary historian get the promotion.

Though he has said that Martin C. Putna's sexual orientation itself is not an issue, Zeman has largely refused to fully explain his stance, insisting he doesn't want to "humiliate" the candidate "by naming the reasons publicly." But over the weekend, Zeman told Czech public TV that he "does not recognize people aspiring to teach at universities" who attend gay festivals.

A chain smoker with a well-document soft spot for alcohol, Zeman made international headlines when he was prime minister with outspoken comments, including comparing late Palestinian leader Yasser Arafat to Adolf Hitler. In his short time as the Czech Republic's ceremonial leader, the 68-year-old Zeman has already sparked an Internet sensation, appearing to show up drunk at a rare public display of the country's crown jewels earlier this month.

Putna, a lecturer at Prague's prestigious Charles University, openly supported Zeman's rival in presidential elections in January and ridiculed Zeman in the campaign.

Zeman's remarks have been condemned by politicians across the political spectrum. A pro-Putna rally is planned for Thursday in front of Prague Castle, the seat of the Czech presidency.

Charles University rector Vaclav Hampl was to meet with Zeman on Wednesday. Unless a "really serious moral wrongdoing" is behind Zeman's refusal to appoint Putna, Hampl said, his action would constitute "nothing other than an absolutely unacceptable political interference."

The government has already approved a slate of 65 candidates to be appointed at a ceremony on June 11, the Education Ministry said. Zeman's predecessor, conservative Vaclav Klaus named more than 1,500 professors and rejected not a single one.

Source: http://news.yahoo.com/czech-president-dispute-over-gay-rights-151437982.html

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14 closely related crocodiles existed around 5 million years ago

Public release date: 21-May-2013
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Contact: Marcelo S?nchez-Villagra
m.sanchez@pim.uzh.ch
41-446-342-342
University of Zurich

Nowadays, the most diverse species of crocodile are found in northern South America and Southeast Asia: As many as six species of alligator and four true crocodiles exist, although no more than two or three ever live alongside one another at the same time. It was a different story nine to about five million years ago, however, when a total of 14 different crocodile species existed and at least seven of them occupied the same area at the same time, as an international team headed by paleontologists Marcelo Snchez and Torsten Scheyer from the University of Zurich is now able to reveal. The deltas of the Amazonas and the Urumaco, a river on the Gulf of Venezuela that no longer exists, boasted an abundance of extremely diverse, highly specialized species of crocodile that has remained unparalleled ever since.

Two new fossil crocodile species discovered

While studying the wealth of fossil crocodiles from the Miocene in the Urumaco region, the scientists discovered two new crocodile species: the Globidentosuchus brachyrostris, which belonged to the caiman family and had spherical teeth, and Crocodylus falconensis, a crocodile that the researchers assume grew up to well over four meters long. As Snchez and his team reveal, Venezuela's fossils include all the families of crocodile species that still exist all over the world today: the Crocodylidae, the so-called true crocodiles; the Alligatoridae, which, besides the true alligators, also include caimans; and the Gavialidae, which are characterized by their extremely long, thin snouts and are only found in Southeast Asia nowadays.

On account of the species' extremely different jaw shapes, the researchers are convinced that the different crocodilians were highly specialized feeders: With their pointed, slender snouts, the fossil gharials must have preyed on fish. "Gharials occupied the niche in the habitat that was filled by dolphins after they became extinct," Snchez suspects. With its spherical teeth, however, Globidentosuchus brachyrostris most likely specialized in shellfish, snails or crabs. And giant crocodiles, which grew up to 12 meters long, fed on turtles, giant rodents and smaller crocodiles. "There were no predators back then in South America that could have hunted the three-meter-long turtles or giant rodents. Giant crocodiles occupied this very niche," explains Scheyer.

Andean uplift led to extinction

The unusual variety of species in the coastal and brackish water regions of Urumaco and Amazonas came to an end around 5 million years ago when all the crocodile species died out. The reason behind their extinction, however, was not temperature or climate changes temperatures in the Caribbean remained stable around the Miocene/Pliocene boundary. Instead, it was caused by a tectonic event: "The Andean uplift changed the courses of rivers. As a result, the Amazon River no longer drains into the Caribbean, but the considerably cooler Atlantic Ocean," explains Snchez. With the destruction of the habitat, an entirely new fauna emerged that we know from the Orinoco and Amazon regions today. In the earlier Urumaco region, however, a very dry climate has prevailed ever since the Urumaco River dried up.

###

Literature:

T. M. Scheyer, O. A. Aguilera, M. Delfino, D. C. Fortier, A. A. Carlini, R. Snchez, J. D. Carrillo-Briceo, L. Quiroz, and M. R. Snchez-Villagra. Crocodylian diversity peak and extinction in the late Cenozoic of the northern Neotropics. Nature Communications. May 21, 2013. doi:10.1038/ncomms2940I:

Contact:

Prof. Marcelo Snchez-Villagra
Paleontological Institute and Museum
University of Zurich
Phone +41 44 634 23 42
E-mail: m.sanchez@pim.uzh.ch

Dr. Torsten Scheyer
Paleontological Institute and Museum
University of Zurich
Phone +41 44 634 23 22
E-mail: tscheyer@pim.uzh.ch

---

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Public release date: 21-May-2013
[ | E-mail | Share ]

Contact: Marcelo S?nchez-Villagra
m.sanchez@pim.uzh.ch
41-446-342-342
University of Zurich

Nowadays, the most diverse species of crocodile are found in northern South America and Southeast Asia: As many as six species of alligator and four true crocodiles exist, although no more than two or three ever live alongside one another at the same time. It was a different story nine to about five million years ago, however, when a total of 14 different crocodile species existed and at least seven of them occupied the same area at the same time, as an international team headed by paleontologists Marcelo Snchez and Torsten Scheyer from the University of Zurich is now able to reveal. The deltas of the Amazonas and the Urumaco, a river on the Gulf of Venezuela that no longer exists, boasted an abundance of extremely diverse, highly specialized species of crocodile that has remained unparalleled ever since.

Two new fossil crocodile species discovered

While studying the wealth of fossil crocodiles from the Miocene in the Urumaco region, the scientists discovered two new crocodile species: the Globidentosuchus brachyrostris, which belonged to the caiman family and had spherical teeth, and Crocodylus falconensis, a crocodile that the researchers assume grew up to well over four meters long. As Snchez and his team reveal, Venezuela's fossils include all the families of crocodile species that still exist all over the world today: the Crocodylidae, the so-called true crocodiles; the Alligatoridae, which, besides the true alligators, also include caimans; and the Gavialidae, which are characterized by their extremely long, thin snouts and are only found in Southeast Asia nowadays.

On account of the species' extremely different jaw shapes, the researchers are convinced that the different crocodilians were highly specialized feeders: With their pointed, slender snouts, the fossil gharials must have preyed on fish. "Gharials occupied the niche in the habitat that was filled by dolphins after they became extinct," Snchez suspects. With its spherical teeth, however, Globidentosuchus brachyrostris most likely specialized in shellfish, snails or crabs. And giant crocodiles, which grew up to 12 meters long, fed on turtles, giant rodents and smaller crocodiles. "There were no predators back then in South America that could have hunted the three-meter-long turtles or giant rodents. Giant crocodiles occupied this very niche," explains Scheyer.

Andean uplift led to extinction

The unusual variety of species in the coastal and brackish water regions of Urumaco and Amazonas came to an end around 5 million years ago when all the crocodile species died out. The reason behind their extinction, however, was not temperature or climate changes temperatures in the Caribbean remained stable around the Miocene/Pliocene boundary. Instead, it was caused by a tectonic event: "The Andean uplift changed the courses of rivers. As a result, the Amazon River no longer drains into the Caribbean, but the considerably cooler Atlantic Ocean," explains Snchez. With the destruction of the habitat, an entirely new fauna emerged that we know from the Orinoco and Amazon regions today. In the earlier Urumaco region, however, a very dry climate has prevailed ever since the Urumaco River dried up.

###

Literature:

T. M. Scheyer, O. A. Aguilera, M. Delfino, D. C. Fortier, A. A. Carlini, R. Snchez, J. D. Carrillo-Briceo, L. Quiroz, and M. R. Snchez-Villagra. Crocodylian diversity peak and extinction in the late Cenozoic of the northern Neotropics. Nature Communications. May 21, 2013. doi:10.1038/ncomms2940I:

Contact:

Prof. Marcelo Snchez-Villagra
Paleontological Institute and Museum
University of Zurich
Phone +41 44 634 23 42
E-mail: m.sanchez@pim.uzh.ch

Dr. Torsten Scheyer
Paleontological Institute and Museum
University of Zurich
Phone +41 44 634 23 22
E-mail: tscheyer@pim.uzh.ch

---

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Source: http://www.eurekalert.org/pub_releases/2013-05/uoz-1cr052113.php

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Not just blowing in the wind: Compressing air for renewable energy storage

May 20, 2013 ? Enough Northwest wind energy to power about 85,000 homes each month could be stored in porous rocks deep underground for later use, according to a new, comprehensive study. Researchers at the Department of Energy's Pacific Northwest National Laboratory and Bonneville Power Administration identified two unique methods for this energy storage approach and two eastern Washington locations to put them into practice.

Compressed air energy storage plants could help save the region's abundant wind power -- which is often produced at night when winds are strong and energy demand is low -- for later, when demand is high and power supplies are more strained. These plants can also switch between energy storage and power generation within minutes, providing flexibility to balance the region's highly variable wind energy generation throughout the day.

"With Renewable Portfolio Standards requiring states to have as much as 20 or 30 percent of their electricity come from variable sources such as wind and the sun, compressed air energy storage plants can play a valuable role in helping manage and integrate renewable power onto the Northwest's electric grid," said Steve Knudsen, who managed the study for the BPA.

Geologic energy savings accounts

All compressed air energy storage plants work under the same basic premise. When power is abundant, it's drawn from the electric grid and used to power a large air compressor, which pushes pressurized air into an underground geologic storage structure. Later, when power demand is high, the stored air is released back up to the surface, where it is heated and rushes through turbines to generate electricity. Compressed air energy storage plants can re-generate as much as 80 percent of the electricity they take in.

The world's two existing compressed air energy storage plants -- one in Alabama, the other in Germany -- use human-made salt caverns to store excess electricity. The PNNL-BPA study examined a different approach: using natural, porous rock reservoirs that are deep underground to store renewable energy.

Interest in the technology has increased greatly in the past decade as utilities and others seek better ways to integrate renewable energy onto the power grid. About 13 percent, or nearly 8,600 megawatts, of the Northwest's power supply comes from of wind. This prompted BPA and PNNL to investigate whether the technology could be used in the Northwest.

To find potential sites, the research team reviewed the Columbia Plateau Province, a thick layer of volcanic basalt rock that covers much of the region. The team looked for underground basalt reservoirs that were at least 1,500 feet deep, 30 feet thick and close to high-voltage transmission lines, among other criteria.

They then examined public data from wells drilled for gas exploration or research at the Hanford Site in southeastern Washington. Well data was plugged into PNNL's STOMP computer model, which simulates the movement of fluids below ground, to determine how much air the various sites under consideration could reliably hold and return to the surface.

Two different, complementary designs

Analysis identified two particularly promising locations in eastern Washington. One location, dubbed the Columbia Hills Site, is just north of Boardman, Ore., on the Washington side of the Columbia River. The second, called the Yakima Minerals Site, is about 10 miles north of Selah, Wash., in an area called the Yakima Canyon.

But the research team determined the two sites are suitable for two very different kinds of compressed air energy storage facilities. The Columbia Hills Site could access a nearby natural gas pipeline, making it a good fit for a conventional compressed air energy facility. Such a conventional facility would burn a small amount of natural gas to heat compressed air that's released from underground storage. The heated air would then generate more than twice the power than a typical natural gas power plant.

The Yakima Minerals Site, however, doesn't have easy access to natural gas. So the research team devised a different kind of compressed air energy storage facility: one that uses geothermal energy. This hybrid facility would extract geothermal heat from deep underground to power a chiller that would cool the facility's air compressors, making them more efficient. Geothermal energy would also re-heat the air as it returns to the surface.

"Combining geothermal energy with compressed air energy storage is a creative concept that was developed to tackle engineering issues at the Yakima Minerals Site," said PNNL Laboratory Fellow and project leader Pete McGrail. "Our hybrid facility concept significantly expands geothermal energy beyond its traditional use as a renewable baseload power generation technology."

The study indicates both facilities could provide energy storage during extended periods of time. This could especially help the Northwest during the spring, when sometimes there is more wind and hydroelectric power than the region can absorb. The combination of heavy runoff from melting snow and a large amount of wind, which often blows at night when demand for electricity is low, can spike power production in the region. Power system managers have a few options to keep the regional power grid stable in such a situation, including reducing power generation or storing the excess power supply. Energy storage technologies such as compressed air energy storage can help the region make the most of its excess clean energy production.

Working with the Northwest Power and Conservation Council, BPA will now use the performance and economic data from the study to perform an in-depth analysis of the net benefits compressed air energy storage could bring to the Pacific Northwest. The results could be used by one or more regional utilities to develop a commercial compressed air energy storage demonstration project.

The $790,000 joint feasibility study was funded by BPA's Technology Innovation Office, PNNL and several project partners: Seattle City Light, Washington State University Tri-Cities, GreenFire Energy, Snohomish County Public Utility District, Dresser-Rand, Puget Sound Energy, Ramgen Power Systems, NW Natural, Magnum Energy and Portland General Electric.

REFRENCE: BP McGrail, JE Cabe, CL Davidson, FS Knudsen, DH Bacon, MD Bearden, MA Chamness, JA Horner, SP Reidel, HT Schaef, FA Spane, PD Thorne, "Techno-economic Performance Evaluation of Compressed Air Energy Storage in the Pacific Northwest," February 2013, http://caes.pnnl.gov/pdf/PNNL-22235.pdf.

COMPRESSED AIR ENERGY STORAGE SITES

Columbia Hills Site

? Location: north of Boardman, Ore., on Washington side of Columbia River

? Plant type: Conventional, which pairs compressed air storage with a natural gas power plant.

? Power generation capacity: 207 megawatts

? Energy storage capacity: 231 megawatts

? Estimated levelized power cost: as low as 6.4 cents per kilowatt-hour

? Would work well for frequent energy storage

? Continuous storage for up to 40 days

Yakima Minerals Site

? Location: 10 miles north of Selah, Wash.

? Plant type: Hybrid, which pairs geothermal heat with compressed air storage

? Power generation capacity: 83 megawatts

? Energy storage capacity: 150 megawatts

? Estimated levelized power cost: as low as 11.8 cents per kilowatt-hour

? No greenhouse gas emissions

? Potential for future expansion

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/mb3lmNXBYK8/130520142823.htm

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Leading explanations for whooping cough's resurgence don't stand up to scrutiny

Public release date: 20-May-2013
[ | E-mail | Share ]

Contact: Jim Erickson
ericksn@umich.edu
734-647-1842
University of Michigan

ANN ARBORWhooping cough has exploded in the United States and some other developed countries in recent decades, and many experts suspect ineffective childhood vaccines for the alarming resurgence.

Some say the vaccine wears off quicker than public health officials had previously believed. Others suggest that the vaccine protects against illness but does not prevent transmission of the bacterial disease, which is also known as pertussis.

But a University of Michigan-led research team has concluded that neither of these proposed mechanisms for the resurgence of pertussis is supported by the best available evidence. In a study that reviewed 30 years of data from Thailand, they found that vaccines provided long-livedpossibly lifelongprotection against the disease and substantially reduced transmission, as well.

"What we found goes against much of what is currently suspected about pertussis resurgence," said U-M population ecologist and epidemiologist Pejman Rohani. "It's not difficult for us epidemiologists to propose some possible mechanism behind the resurgence, but what's been missing so far is an effort to challenge each of these hypotheses to explain the data. That's exactly what we did."

A paper summarizing the team's findings is scheduled for online publication in the journal Proceedings of the National Academy of Sciences on May 20. The lead author is Julie Blackwood, a postdoctoral research associate in Rohani's lab at the U-M Department of Ecology and Evolutionary Biology.

Thailand was selected as the study site largely because a unique high-resolution dataset of pertussis incidenceincluding monthly case notifications from 72 provinces between 1981 and 2000was obtained from that country's Ministry of Public Health. Equally detailed U.S. incidence data are not available from the federal Centers for Disease Control and Prevention, Rohani said.

The researchers expressed several of the leading hypotheses for the resurgence of pertussis in mathematical terms, then used statistical methods to test how well each of these transmission models explained the Thai data. The best fit came from a model that assumed lifelong immunity following either vaccination or naturally acquired infection.

The researchers found no evidence for a pertussis resurgence in Thailand. In fact, their findings highlighted the success of the country's childhood immunization program, pointing to a vaccine-induced increase in "herd immunity," a reduction in the probability of infection that occurs in a population as the number of immune individuals increases.

"We found very few cases overall, and especially in infants," Blackwood said. "So the big underlying finding is that the vaccine is adequately protecting infants from contracting the infection."

The situation with pertussis in Thailand cannot be directly compared with trends in the U.S. for many reasons, including the fact that the two countries use different types of whooping cough vaccine. Thailand mainly uses what's called a whole-cell vaccine, while an acellular vaccine is used in the U.S. In addition, the vaccination schedule in the two countries differs slightly.

Pertussis is a highly infectious respiratory disease that is responsible for nearly 300,000 deaths worldwide annually, primarily among infants in developing countries. In infants, it causes violent, gasping coughing spells.

The U-M-led Thailand study was funded in part by a $1.7 million, five-year National Institutes of Health grant awarded to Rohani and U-M's Aaron King last year. The grant funds efforts to explain the changing patterns of whooping cough outbreaks by using long-term incidence reports from several countries, along with mathematical models of pertussis transmission and statistical methods for extracting information from data.

###

Funding for the Thailand project was also provided by the U.S. Department of Homeland Security and the Bill and Melinda Gates Vaccine Modeling Initiative. Co-authors of the PNAS paper are Derek A.T. Cummings of Johns Hopkins University, Helene Broutin of the Centre National de la Recherche Scientifique in France and Sopon Iamsirithaworn of Thailand's Ministry of Public Health.

Rohani is a professor of ecology and evolutionary biology, a professor of complex systems and a professor of epidemiology at the U-M School of Public Health. More about Rohani: http://www.lsa.umich.edu/eeb/directory/faculty/rohani

---

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AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Public release date: 20-May-2013
[ | E-mail | Share ]

Contact: Jim Erickson
ericksn@umich.edu
734-647-1842
University of Michigan

ANN ARBORWhooping cough has exploded in the United States and some other developed countries in recent decades, and many experts suspect ineffective childhood vaccines for the alarming resurgence.

Some say the vaccine wears off quicker than public health officials had previously believed. Others suggest that the vaccine protects against illness but does not prevent transmission of the bacterial disease, which is also known as pertussis.

But a University of Michigan-led research team has concluded that neither of these proposed mechanisms for the resurgence of pertussis is supported by the best available evidence. In a study that reviewed 30 years of data from Thailand, they found that vaccines provided long-livedpossibly lifelongprotection against the disease and substantially reduced transmission, as well.

"What we found goes against much of what is currently suspected about pertussis resurgence," said U-M population ecologist and epidemiologist Pejman Rohani. "It's not difficult for us epidemiologists to propose some possible mechanism behind the resurgence, but what's been missing so far is an effort to challenge each of these hypotheses to explain the data. That's exactly what we did."

A paper summarizing the team's findings is scheduled for online publication in the journal Proceedings of the National Academy of Sciences on May 20. The lead author is Julie Blackwood, a postdoctoral research associate in Rohani's lab at the U-M Department of Ecology and Evolutionary Biology.

Thailand was selected as the study site largely because a unique high-resolution dataset of pertussis incidenceincluding monthly case notifications from 72 provinces between 1981 and 2000was obtained from that country's Ministry of Public Health. Equally detailed U.S. incidence data are not available from the federal Centers for Disease Control and Prevention, Rohani said.

The researchers expressed several of the leading hypotheses for the resurgence of pertussis in mathematical terms, then used statistical methods to test how well each of these transmission models explained the Thai data. The best fit came from a model that assumed lifelong immunity following either vaccination or naturally acquired infection.

The researchers found no evidence for a pertussis resurgence in Thailand. In fact, their findings highlighted the success of the country's childhood immunization program, pointing to a vaccine-induced increase in "herd immunity," a reduction in the probability of infection that occurs in a population as the number of immune individuals increases.

"We found very few cases overall, and especially in infants," Blackwood said. "So the big underlying finding is that the vaccine is adequately protecting infants from contracting the infection."

The situation with pertussis in Thailand cannot be directly compared with trends in the U.S. for many reasons, including the fact that the two countries use different types of whooping cough vaccine. Thailand mainly uses what's called a whole-cell vaccine, while an acellular vaccine is used in the U.S. In addition, the vaccination schedule in the two countries differs slightly.

Pertussis is a highly infectious respiratory disease that is responsible for nearly 300,000 deaths worldwide annually, primarily among infants in developing countries. In infants, it causes violent, gasping coughing spells.

The U-M-led Thailand study was funded in part by a $1.7 million, five-year National Institutes of Health grant awarded to Rohani and U-M's Aaron King last year. The grant funds efforts to explain the changing patterns of whooping cough outbreaks by using long-term incidence reports from several countries, along with mathematical models of pertussis transmission and statistical methods for extracting information from data.

###

Funding for the Thailand project was also provided by the U.S. Department of Homeland Security and the Bill and Melinda Gates Vaccine Modeling Initiative. Co-authors of the PNAS paper are Derek A.T. Cummings of Johns Hopkins University, Helene Broutin of the Centre National de la Recherche Scientifique in France and Sopon Iamsirithaworn of Thailand's Ministry of Public Health.

Rohani is a professor of ecology and evolutionary biology, a professor of complex systems and a professor of epidemiology at the U-M School of Public Health. More about Rohani: http://www.lsa.umich.edu/eeb/directory/faculty/rohani

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Source: http://www.eurekalert.org/pub_releases/2013-05/uom-lef051613.php

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Earth's iron core is surprisingly weak

May 20, 2013 ? Researchers have used a diamond anvil cell to squeeze iron at pressures as high as 3 million times that felt at sea level to recreate conditions at the center of Earth. The findings could refine theories of how the planet and its core evolved.

Through laboratory experiments, postdoctoral researcher Arianna Gleason, left, and Wendy Mao, an assistant professor of geological and environmental sciences and of photon science, determined that the iron in Earth's inner core is about 40 percent as strong as previously believed.

The massive ball of iron sitting at the center of Earth is not quite as "rock-solid" as has been thought, say two Stanford mineral physicists. By conducting experiments that simulate the immense pressures deep in the planet's interior, the researchers determined that iron in Earth's inner core is only about 40 percent as strong as previous studies estimated.

This is the first time scientists have been able to experimentally measure the effect of such intense pressure -- as high as 3 million times the pressure Earth's atmosphere exerts at sea level -- in a laboratory. A paper presenting the results of their study is available online in Nature Geoscience.

"The strength of iron under these extreme pressures is startlingly weak," said Arianna Gleason, a postdoctoral researcher in the department of Geological and Environmental Sciences, and lead author of the paper. Wendy Mao, an assistant professor in the department, is the co-author.

"This strength measurement can help us understand how the core deforms over long time scales, which influences how we think about Earth's evolution and planetary evolution in general," Gleason said.

Until now, almost all of what is known about Earth's inner core came from studies tracking seismic waves as they travel from the surface of the planet through the interior. Those studies have shown that the travel time through the inner core isn't the same in every direction, indicating that the inner core itself is not uniform. Over time and subjected to great pressure, the core has developed a sort of fabric as grains of iron elongate and align lengthwise in parallel formations.

The ease and speed with which iron grains in the inner core can deform and align would have influenced the evolution of the early Earth and development of the geomagnetic field. The field is generated by the circulation of liquid iron in the outer core around the solid inner core and shields Earth from the full intensity of solar radiation. Without the geomagnetic field, life -- at least as we know it -- would not be possible on Earth.

"The development of the inner core would certainly have some effect on the geomagnetic field, but just what effect and the magnitude of the effect, we can't say," said Mao. "That is very speculative."

Gleason and Mao conducted their experiments using a diamond anvil cell -- a device that can exert immense pressure on tiny samples clenched between two diamonds. They subjected minute amounts of pure iron to pressures between 200 and 300 gigapascals (equivalent to the pressure of 2 million to 3 million Earth atmospheres). Previous experimental studies were conducted in the range of only 10 gigapascals.

"We really pushed the limit here in terms of experimental conditions," Gleason said. "Pioneering advancements in pressure-generation techniques and improvements in detector sensitivity, for example, used at large X-ray synchrotron facilities, such as Argonne National Lab, have allowed us to make these new measurements."

In addition to intense pressures, the inner core also has extreme temperatures. The boundary between the inner and outer core has temperatures comparable to the surface of the sun. Simultaneously simulating both the pressure and temperature at the inner core isn't yet possible in the laboratory, though Gleason and Mao are working on that for future studies. (For this study, Gleason mathematically extrapolated from their pressure data to factor in the effect of temperature.)

Gleason and Mao expect their findings will help other researchers set more realistic variables for conducting their own experiments.

"People modeling the inner core haven't had many experimental constraints, because it's so difficult to make measurements under those conditions," Mao said. "There really weren't constraints on how strong the core was, so this is really a fundamental new constraint."

Source: http://feeds.sciencedaily.com/~r/sciencedaily/top_news/top_science/~3/uYHvEXbKtnY/130520095404.htm

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Tornadoes slam Plains, Midwest; 1 dead in Okla.

A flag flies in the debris of a mobile home after a tornado struck a mobile home park near Dale, Okla., Sunday, May 19, 2013. (AP Photo Sue Ogrocki)

A flag flies in the debris of a mobile home after a tornado struck a mobile home park near Dale, Okla., Sunday, May 19, 2013. (AP Photo Sue Ogrocki)

A tornado touches down southwest of Wichita, Kan. near the town of Viola on Sunday, May 19, 2013. The tornado was part of a line of storms that past through the central plains on Sunday. (AP Photo/The Wichita Eagle, Travis Heying)

Alli Christian, left, returns Jessica Wilkinson's dog Bella to her after finding her among the wreckage of Wilkinson's home shortly after a tornado struck near 156th street and Franklin Road on Sunday, May 19, 2013 in Norman, Okla. No one was in the home when the storm struck. (AP Photo/The Oklahoman, Steve Sisney)

Debris is scattered in what was a mobile home park where a tornado struck near Dale, Okla., Sunday, May 19, 2013. (AP Photo Sue Ogrocki)

The frame of a mobile home is pictured with debris after a tornado hit a mobile home park near Dale, Okla., Sunday, May 19, 2013. (AP Photo Sue Ogrocki)

SHAWNEE, Okla. (AP) ? Hearing on the radio that a violent storm was approaching her rural Oklahoma neighborhood, Lindsay Carter took advantage of the advanced warning, gathered her belongings and fled. When she returned, there was little left of the community she called home.

Several tornadoes struck parts of the nation's midsection Sunday, concentrating damage in central Oklahoma and Wichita, Kan. One person was killed near Shawnee, Okla., and 21 injuries were reported throughout the state.

Victims and emergency responders might not get much of reprieve as the National Oceanic and Atmospheric Administration's Storm Prediction Center was forecasting similar weather for Monday over much of the same area.

The worst of the damage Sunday appeared to be at the Steelman Estates Mobile Home Park located amid gently rolling hills about 35 miles southeast of Oklahoma City.

"It took a dead hit," resident James Hoke said. Emerging from a storm cellar where he sought refuge with his wife and two children, Hoke found that their mobile home had vanished. "Everything is gone."

Hoke said he started trying to help neighbors and found his wife's father covered in rubble.

"My father-in-law was buried under the house. We had to pull Sheetrock off of him," Hoke said.

Forecasters had been warning of bad weather since last Wednesday and on Sunday said conditions had ripened for powerful tornadoes. Wall-to-wall broadcasts of storm information spread the word Sunday, leaving Pottawatomie County Sheriff Mike Booth grateful.

"There was a possibility a lot more people could have been injured," Booth said. "This is the worst I've seen in Pottawatomie County in my 25 years of law enforcement."

Carter had heard on a radio broadcast that a storm that had originated southwest of Oklahoma City was headed toward Shawnee.

"We got in the truck and left," Carter said. With upward of 30 minutes' notice for Pottawatomie County, Carter had time to leave one of the few frame homes in Steelman Estates ? and most of her house was intact when she returned.

"I walked up, and the house was OK. Part of the roof was gone," she said.

The scene was different a short distance away.

"Trees were all gone. I walked further down and all those houses were gone," she said.

Booth said a 79-year-old man was found dead out in the open at Steelman Estates, but the sheriff didn't have details on where he had lived.

"You can see where there's absolutely nothing, then there are places where you have mobile home frames on top of each other, debris piled up," Booth said. "It looks like there's been heavy equipment in there on a demolition tour.

"It's pretty bad. It's pretty much wiped out," he said.

Tornadoes were reported Sunday in Iowa, Kansas and Oklahoma as part of a storm system that stretched from Texas to Minnesota.

Following the Oklahoma twisters, local emergency officials went from home site to home site in an effort to account for everyone. Keli Cain, a spokeswoman for the Oklahoma Department of Emergency Management, said that, many times in such situations, people who are not found immediately are discovered later to have left the area ahead of the storm.

A storm spotter told the National Weather Service that the tornado left the earth "scoured" at the mobile home park. At the nearby intersection of Interstate 40 and U.S. 177, a half-dozen tractor-trailers were blown over, closing both highways for a time.

"It seemed like it went on forever. It was a big rumbling for a long time," said Shawn Savory, standing outside his damaged remodeling business in Shawnee. "It was close enough that you could feel like you could reach out and touch it."

Gov. Mary Fallin declared an emergency for 16 Oklahoma counties that suffered from severe storms and flooding during the weekend. The declaration lets local governments acquire goods quickly to respond to their residents' needs and puts the state in line for federal help if it becomes necessary.

Heavy rains and straight-line winds hit much of western Oklahoma on Saturday. Tornadoes were also reported Sunday at Edmond, Arcadia and near Wellston to the north and northeast of Oklahoma City. The supercell that generated the twisters weakened as it approached Tulsa, 90 miles to the northeast.

"I knew it was coming," said Randy Grau, who huddled with his wife and two young sons in their Edmond home's safe room when the tornado hit. He said he peered out his window as the weather worsened and believed he saw a flock of birds heading down the street.

"Then I realized it was swirling debris. That's when we shut the door of the safe room," said Grau, adding that they remained in the room for 10 minutes.

In Wichita, Kan., a tornado touched down near Mid-Content Airport on the city's southwest side shortly before 4 p.m., knocking out power to thousands of homes and businesses but bypassing the most populated areas of Kansas' biggest city. The Wichita tornado was an EF1 on the enhanced Fujita scale, with winds of 110 mph, according to the weather service.

Sedgwick County Emergency Management Director Randy Duncan said there were no reports of fatalities or injuries in Kansas.

There were also two reports of tornadoes touching down in Iowa on Sunday night, including one near Huxley, about 20 miles north of Des Moines, and one in Grundy County, which is northeast of Des Moines, according to the Des Moines Register. There were no immediate reports of major damage or injuries.

In Oklahoma, aerial television news footage showed homes with significant damage northeast of Oklahoma City. Some outbuildings appeared to have been leveled, and some homes' roofs or walls had been knocked down.

In Katie Leathers' backyard in Edmond, the family's trampoline was tossed through a section of fence and a giant tree uprooted.

"I saw all the trees waving, and that's when I grabbed everyone and got into two closets," Leathers said. "All these trees just snapped."

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Associated Press writers Ken Miller in Shawnee, Heather Hollingsworth in Kansas City, Mo., and Kelly P. Kissel in Little Rock, Ark., contributed to this report.

Associated Press

Source: http://hosted2.ap.org/APDEFAULT/3d281c11a96b4ad082fe88aa0db04305/Article_2013-05-20-Severe%20Weather/id-803d0ada940f46ae9ff65e53643bb575

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