Sensor descends down a hole in the ice as part of the installation of the IceCube telescope. IceCube is among the most ambitious scientific construction projects ever attempted. Credit:NSF/B. Gudbjartsson

A massive telescope buried in the Antarctic ice has detected 28 extremely high-energy neutrinos -- elementary particles that likely originate outside our solar system. Two of these neutrinos had energies many thousands of times higher than the highest-energy neutrino that any man-made particle accelerator has ever produced, according to a team of IceCube Neutrino Observatory researchers that includes Penn State scientists. These new record-breaking neutrinos had energies greater than 1,000,000,000,000,000 electron volts or, as the scientists say, 1 peta-electron volt (PeV).

"Scientists have been searching high and low for these super-energetic neutrinos using detectors buried under mountains, submerged in deep lakes and ocean trenches, lofted into the stratosphere by special balloons, and in the deep clear Antarctic ice at the South Pole," said Penn State Professor of Physics and Astronomy and Astrophysics Doug Cowen, who has worked on IceCube for over a decade. "To have finally seen them after all these years is immensely gratifying." The discovery was announced this week at the IceCube Particle Astrophysics Symposium in Madison, Wisconsin.

Because high-energy neutrinos rarely interact with matter and are not deflected by magnetic fields in our galaxy, they can carry information about the workings of the highest-energy and most-distant phenomena in the universe. But although billions of neutrinos pass through the Earth every second, the vast majority are lower-energy particles that originate either in the Sun or in the Earth's atmosphere.  Far rarer are the high-energy neutrinos that more likely would have been created much farther from Earth in the most powerful cosmic events -- gamma ray bursts, black holes, or the birth of stars.

"While it is premature to speculate about the precise origin of these neutrinos, their energies are too high to be produced by cosmic rays interacting in the Earth's atmosphere, strongly suggesting that they are produced by distant accelerators of subatomic particles elsewhere in our galaxy, or even farther away," said Penn State Associate Professor of Physics Tyce DeYoung, the deputy spokesperson of the IceCube Collaboration.

The IceCube collaboration is continuing to refine and expand the search with new data and new analysis techniques, which may reveal additional high-energy events and possibly point to their astrophysical source or sources.  "Although further observations will be required to confirm the extraterrestrial origin of these neutrinos, after more than ten years of work building this detector, it's very exciting to see what may be the first glimpse of a new window on our universe," DeYoung said.

The IceCube Collaboration, which includes several Penn State faculty, postdoctoral, graduate and undergraduate researchers, reported 28 high-energy neutrino events captured by the detector between May 2010 and May 2012.  These events, including two that exceeded the unprecedented energy level of 1 PeV, were among the main goals for building the IceCube detector.

IceCube is comprised of more than 5,000 digital/optical modules melted into in a cubic kilometer of ice at the South Pole. The observatory, supported by the U.S. National Science Foundation, detects neutrinos through the fleeting flashes of blue light produced when a neutrino interacts with a water molecule in the ice.

The first hints of high-energy neutrinos came with the discovery in April 2012 of two neutrinos with energies in excess of 1 PeV.  An analysis of those events was reported recently in a paper submitted to the journal Physical Review Letters. An intensified follow-up search turned up 26 additional events exceeding 30 tera-electron volts (the energy of one TeV is one-thousandth that of a PeV). The results of this follow-up search will be described in a forthcoming paper in a scientific journal.

The IceCube Neutrino Observatory was built under a National Science Foundation (NSF) Major Research Equipment and Facilities Construction grant, with assistance from partner funding agencies in Germany, Sweden, and Belgium. The NSF Division of Polar Programs continues to support the project with a Maintenance and Operations grant, in conjunction with support from international scientific funding agencies. The scientific collaboration includes 250 physicists and engineers from the U.S., Germany, Sweden, Belgium, Canada, Switzerland, Japan, New Zealand, and Australia.

[ D C / B K K ]

CONTACTS

• Doug Cowen: +1 814-863-5943, -3537, cowen@phys.psu.edu
• Barbara Kennedy (PIO): +1 814-863-4682, science@psu.edu

Has forensic science, in fact, become a woman's field?

Yes and no, says Jenifer Smith, a professor of forensic science at Penn State and retired DNA analyst and special agent for the FBI. "Currently 74 percent of the students in our forensic science program are young women, and they continue to fill the ranks of various laboratories. It's one of the areas of science in which women outnumber men. In many ways, we are a STEM [Science, Technology, Engineering and Math] success story."

This hasn't always been the case, recalls Smith. "My interest in forensic science was solidified during an internship at the Office of the Chief Medical Examiner in New York City in 1980," she says. "I noticed at the time that the lab had women working in it, but they were technicians. All of the supervisory positions were held by men."

Prior to DNA testing, explains Smith, the technical analysis of evidence from crime scenes and death investigations was regarded derisively as "somewhere between voodoo and witchcraft as far as most serious scientists were concerned." Perhaps this image of forensic science as a softer or more human science is what originally opened the door to more females in the field, she speculates.

DNA profiling—a technique first reported in 1984 by Sir Alec Jeffreys at the University of Leicester in England—is the basis of several national DNA databases that have revolutionized the field by giving it a statistically valid and reliable tool. However, some other tools of crime scene investigation—such as hair microscopy, bite mark comparisons, firearm tool mark analysis and shoe print comparisons—are still regarded as less scientifically rigorous and accurate. (As an aside, Smith notes that any technique, even DNA analysis and blood typing, can produce wrong results if tests are conducted improperly or results are conveyed inaccurately in trial testimony.)

Regardless of why forensic science first swung open its doors to women, says Smith, the fact is that the glass ceiling hasn't yet been completely shattered where gender is concerned. "On the one hand, if you look at the board of the American Society of Crime Lab Directors, nearly half of the positions are held by women who are directors of their respective laboratories," she notes.

"However, currently, the larger federal labs are still largely filled with women at the technical or bench level, and while there are some moving into management positions, to date none of these labs are led by a woman." She adds, "I was only the second female unit chief in the history of the FBI laboratory from 1995-2001, but one of my friends, Melissa Smrz, nearly made it to the top job, as she was deputy assistant director until her retirement in 2011."

To any young woman out there watching CSI shows and dreaming about going into forensic science, Smith has some myth-busting words of advice. "Despite what you may see on television, we leave the Prada stilettos at home when processing a crime scene," she says with a laugh. "And the 'haute couture' clothing of crime scene fashion are white Tyvek 'bunny suits' and blue hair and feet covers."

Of greater concern to prospective forensic scientists, she explains, is that the work "is 24/7 and will take precedence over many other events in your life. Additionally, it can be very emotionally strenuous work for both men and women because you will be responsible for dealing with the aftermath of acts of violence that most human beings only see in fictitious TV and movie scenes." Unlike the television shows, "we don't solve all crimes in one or two episodes," she notes. "The ones that still remain with me are the ones we never brought to resolution."

As to the field having some of the issues—including a gender wage gap—that tend to plague female-dominated professions, Smith says, "For me, there was extreme satisfaction in having a job in which I could apply my technical expertise. I loved being an applied scientist and I always enjoyed discovering new approaches that helped us fill capability gaps. The salary issue for me was secondary to the satisfaction gained by a job well done and that was a good thing because the majority of forensic science jobs are in the public service or government sector."

[ Melissa Beattie-Moss ]

Jenifer Smith, Associate Director for Undergraduate Education in Forensic Science, can be reached at jas1110@psu.edu.

Shown in blue is chromatin -- the condensed form of DNA that the cell remodels to form chromosomes. The PAD4 enzyme decondenses chromatin by loosening up the interaction between DNA and special proteins called histones. The histones modified by PAD4 are shown in fuchsia. This process helps to form both a bacteria-killing NET -- which is comprised of infection-combatting white blood cells called neutrophils -- and the fluffy, scattered ball that comprises a blood clot. Credit: Wang lab, Penn State University. Originally published in the Journal of Cell Biology (Citation: Wang, Y., et al. 2009. J. Cell Biol. doi:10.1083/jcb.200806072).

A gene associated with both protection against bacterial infection and excessive blood clotting could offer new insights into treatment strategies for deep-vein thrombosis -- the formation of a harmful clot in a deep vein. The gene produces an enzyme that, if inhibited via a specific drug therapy, could offer hope to patients prone to deep-vein clots, such as those that sometimes form in the legs during lengthy airplane flights or during recuperation after major surgery. The research, which was led by Yanming Wang, a Penn State University associate professor of biochemistry and molecular biology, and Denisa Wagner, senior author with decades of research on thrombosis at the Boston Children's Hospital and the Harvard University Medical School, will be published in in the Online Early Edition of the journal Proceedings of the National Academy of Sciences during the week ending 10 May 2013.

The team's new findings are an extension of previous research by Wang and other scientists. In earlier studies, Wang and his colleagues had revealed that a gene in mice called Pad4 (peptidylarginine deiminase 4) produces an enzyme that plays an important role in protecting the body from infection. The researchers discovered that cells with a functioning PAD4 enzyme are able to build around themselves a protective, bacteria-killing web that is dubbed a NET (neutrophil extracellular trap).

Now, in their new research, team members have studied the PAD4 enzyme's role in clotting. Wang explained that, as a part of its NET-producing duties, PAD4 regulates the formation of chromatin -- the condensed form of DNA that the cell remodels to form chromosomes. "PAD4 decondenses chromatin by loosening up the interaction between DNA and special proteins called histones. The resulting chromatin threads then combine with protein fibers, blood platelets, and other materials to become, not only the bacteria-killing NET, but also the fluffy, scattered ball that comprises a blood clot." Wang added that, in some individuals, blood clots tend to form within deep veins. These clots can then travel to the heart, causing cardiac arrest, or to the lungs, causing breathing problems.

In one of their experiments, team members compared mice with a normally functioning Pad4 gene to mice with a defective gene. They found that, when veins were constricted, genetically normal mice -- those able to produce the PAD4 enzyme -- formed clots as expected. However, genetically mutated mice -- those unable to produce the enzyme -- did not form clots normally. In fact, the scientists noted a two-fold difference in clot formation between genetically normal and genetically abnormal mice at six hours after the procedure. After 48 hours, the difference had reached 10-fold. "We noted some clotting activity in these genetically abnormal mice, but the clots were not as bulky and were not maintained over time," Wang said. "Clearly, the PAD4 enzyme plays a critical role in the formation of a blood clot, as well as in the formation of a bacteria-fighting NET."

In another experiment, the research team transferred infection-combatting white blood cells -- called neutrophils -- from normal mice to genetically mutated mice. First author Kim Martinod, a graduate student in the Immunology Graduate Program at the Harvard University Medical School, found that, in response to vein constriction, these "rescued" mice now could function normally, forming clots as efficiently as mice with a functioning Pad4 gene, demonstrating that the Pad4 gene did produce a functioning PAD4 enzyme in these white blood cells to regulate blood clotting.

"PAD4, which is also called PADI4 in humans, is a necessary enzyme involved in multiple disorders," Wang explained. "On the one hand, it plays an integral part in the body's defense system, as we showed in earlier work: It is necessary in the production of the protective, bacteria-killing NET. On the other hand, our earlier work also showed that this enzyme acts to silence tumor-suppressor genes. Now, in our new research, we are starting to see that its overactivity also may be part of the reason that some individuals suffer from deep-vein clotting." Wang added that patients prone to deep-vein thrombosis might benefit from drugs that target the PAD4 enzyme. "In future research, specific drug therapies could be developed and tested with the goal of targeting this enzyme," Wang said. "If we could find a way to dial back the enzyme's clot-forming effects, we might be able to offer new hope to patients suffering from clotting disorders and deep-vein thrombosis."

In addition to Wang, Wagner, and Martinod, other scientists who contributed to this research include Jing Hu from Penn State; Melanie Demers, Tobias A. Fuchs, Siu Ling Wong, and Alexander Brill from the Harvard University Medical School and Boston Children's Hospital; and Maureen Gallant from Boston Children's Hospital.

The research was funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health and the National Cancer Institute.

[ Katrina Voss ]

CONTACTS

• Yanming Wang: 814-865-3775, yuw12@psu.edu
• Barbara Kennedy (PIO): 814-863-4682, science@psu.edu

GRANT NUMBERS

• R01 HL095091, R01 HL041002, and R01 CA136856.

Some scientists are sounding the alarm about the wastefulness of using helium -- a rare, non-renewable gas -- to fill party balloons. Why? As an essential resource in technologies such as medical imaging, rocket engines, and surveillance devices, it turns out that helium does a lot more than give our balloons a lift. And despite being the second most abundant element in the universe, most of our supply in the Earth’s atmosphere simply floats off into space and is lost.

Are we running out of helium on Earth?

Moses Chan, Evan Pugh Professor of Physics at Penn State, explains that the world’s supply of helium is a byproduct of natural gas production, with the Texas Panhandle arguably being the helium capital of the world. However, says Chan, “Very few natural gas wells in the world have enough helium in the well to make it economical to separate helium from natural gas. The gas wells with the most helium have only about 0.3 percent, so it is in short supply.”

In response to the element’s scarcity, the United States has been stockpiling helium since the 1960s in a National Helium Reserve called the Bush Dome, a deep underground reservoir outside of Amarillo, Texas. By the mid 1970s 1.2 billion cubic meters of the gas was stored there. The current reserve is approximately 0.6 billion cubic meters, or roughly 4 times the current world market.

But, Chan notes, in 1996 the Helium Privatization Act mandated that the Department of the Interior sell off all the stockpiled helium by 2015. “As a consequence,” he says, “the United States government is selling the equivalent of 40 percent of the world market of helium at a below-market price.”

“This action discourages the active exploration of helium,” Chan explains, “since companies can buy it from the United States at a cheap price and sell it at a premium.” Chan, who served on the National Research Council’s Committee on Understanding the Impact of Selling the Helium Reserve and co-authored its report, adds that the shortages in the last couple of years are also due to the small number of helium plants worldwide (12 at last count) and maintenance and construction problems in plants in Qatar, Algeria, and the United States.

In May of 2012, Chan testified before the Senate Committee on Energy and Natural Resources, and pointed out that, in recent years, over 20 prominent research programs at universities and national laboratories had reported shortages of liquid helium, impeding research, sometimes for extended periods.

The solution, he believes, may involve new legislation that allows the Bureau of Land Management to continue to manage the Federal Helium Reserve beyond 2015 to avoid any sudden disruption of the market. “There should be a plan to gradually reduce and curtail the sale of the federal helium for industrial and recreation use,” says Chan. “But the federal reserve helium should continue to be made available for national strategic and scientific needs at a price that is in the national interest. When the federal helium is no longer available for non-strategic industrial use,” Chan adds, “the market price of helium will likely go up and there will be more incentive for the gas industry to explore new gas wells with helium.” Rising prices might also mean “the industries that rely on helium -- semiconductor, fiber optics, welding, etcetera -- will start to conserve and recycle it.”

It should be noted, he adds, that natural gas from the Marcellus shale has no helium because the rocks are porous and any helium that was once there leaked out a long time ago.

“Although scientific use accounts for only 3 percent of all the helium, for scientists who want to cool their experiments to cryogenic temperature, there is no alternative to liquid helium,” concludes Chan. “For MRI machines that need a stable high magnetic field, there is also no alternative. It is estimated that if cost was not an issue, the amount of helium gas trapped in current and future gas wells worldwide could last between 200 or 300 years.” That would buy us some time to figure out how to ensure helium sticks around. However, brace yourself for costs to soar “very high,” he predicts. How high? “It depends on how quickly all major helium users adopt ways to conserve and to recycle. When the current helium-rich gas wells are used up, the price could easily soar tenfold.”

With that kind of ballooning inflation, it seems likely that we’ll be inflating far fewer balloons.

[ Melissa Beattie-Moss ]

In the lecture, Lawrence will describe how astronomers are able to determine the fundamental properties of the universe such as its age, size, composition, and expansion rate, with an emphasis on the recent advances made possible by large ground-based surveys and sophisticated space missions. In addition to the public lecture, Lawrence will give two specialized lectures on 22 and 24 April in S5 Osmond Laboratory. Both of these lectures will be held at 4:00 p.m. The Marker Lectures are sponsored by the Penn State Eberly College of Science.

Lawrence is the U.S. project scientist for the Planck satellite, a third-generation mission launched in 2009 that is investigating the cosmic microwave background -- radiation produced only 370,000 years after the Big Bang. These observations, frequently described as "the photograph of the infant universe," reveal the conditions present in the universe when it first became transparent to radiation. The initial cosmological results from Planck were released in March of 2013. Lawrence will describe these findings and place them in context to our current understanding of the cosmos.

After receiving a doctoral degree in physics from the Massachusetts Institute of Technology in 1983, Lawrence moved to the California Institute of Technology. He has a wide range of research interests, including the properties of extragalactic radio sources, gravitational lensing, and the cosmic microwave background. Since 1998 he has been the deputy project scientist for the Spitzer Space Telescope, a major NASA mission that studied infrared radiation. He also was a visiting scholar at the Institute for Advanced Study in Princeton.

The Marker Lectures were established in 1984 through a gift from Penn State Professor Emeritus of Chemistry Russell Earl Marker, whose pioneering synthetic methods revolutionized the steroid-hormone industry and opened the door to the current era of hormone therapies, including the birth-control pill. The Marker endowment allows the Penn State Eberly College of Science to present annual Marker Lectures in astronomy and astrophysics, the chemical sciences, evolutionary biology, genetic engineering, the mathematical sciences, and physics.

For more information, contact Donald Schneider at 814-863-9554 or dps7@psu.edu, Peter Meszaros at nnp@psu.edu, or Niel Brandt at nbrandt@astro.psu.edu. For access assistance, contact Laurie Dasher at 814-865-0418 or lad31@psu.edu.

[ K V ]

Ribbe's research involves microbiology, chemical biology, and inorganic chemistry. By combining biochemical, spectroscopic and structural approaches, he has spent the past 15 years investigating the mechanisms of cofactor assembly and catalysis in nitrogenase -- an enzyme used by some organisms, such as certain kinds of bacteria, to "fix" atmospheric nitrogen into a biologically useful form.

Ribbe was elected a Fellow of the American Academy of Microbiology and a Fellow of the American Association for the Advancement of Science in 2012 and he was elected a Herman Frasch Foundation Fellow by the American Chemical Society in 2007. He was honored with a Campus Village Distinguished Professor Teaching Award in 2005. He has published numerous scientific papers in Science, the Journal of Biological Chemistry, and Proceedings of the National Academy of Sciences, among other journals.

Ribbe received a doctoral degree in microbiology in 1998, a master's degree in microbiology in 1994, and a bachelor's degree in biology in 1991, all from the University of Bayreuth in Germany. He was a postdoctoral fellow at the University of California at Irvine and is now a professor there.

The Stone Memorial Lecture honors Robert W. Stone who, for 23 years, was the head of the former Department of Microbiology, which merged with the biophysics and biochemistry departments in 1979 to form the present Department of Biochemistry and Molecular Biology.

[ T H / K V ]

A plant biologist with broad interests in processes and patterns of evolution, dePamphilis has focused much of his work on genome sequencing and the generation and analysis of large-scale DNA-expression datasets using bioinformatic and molecular evolutionary approaches. His main areas of interest include the evolution of early flowering plants and the origin of the flower, the functional genomics of parasitic plants, and genome evolution. In addition, dePamphilis is a founder of the Floral Genome Project -- a multi-institutional, multi-collaborator study funded through the National Science Foundation's Plant Genome Research Program. This project is dedicated to the study of evolutionary diversification of floral regulatory genes and pathways throughout the major lineages of flowering plants.

Throughout his career, dePamphilis has had his projects funded by multiple grants from the National Science Foundation Plant Genome Research program. Moreover, dePamphilis's work with the Floral Genome Project and its successor, the Ancestral Angiosperm Genome Project, has resulted in more than 100 research papers and his work has been cited nearly 6,000 times. In addition, dePamphilis has been invited to deliver symposia and seminar lectures around the world and he has earned two Margaret Y. Menzel Awards in 2002 and 1989. He is a member of the American Association for the Advancement of Science, the American Society of Plant Biologists, the American Society of Plant Taxonomists, the Botanical Society of America, the International Association for Plant Taxonomy, the Sigma Xi Honor Society, the Society for Molecular Biology and Evolution, and the Society of Systematic Biologists. He has published numerous scientific papers in such journals as Nature, Science, Genome Biology, Molecular Biology and Evolution, the American Journal of Botany, and Proceedings of the National Academy of Sciences.

Before joining the Penn State faculty in 1998, dePamphilis was an assistant professor of biology at Vanderbilt University. He received doctoral and master's degrees in botany from the University of Georgia in 1988 and 1982, respectively. He received a bachelor's degree in biology from Oberlin College in 1977.

[ K V ]

This composite of images from NASA's Chandra X-ray Observatory shows the remnant of Kepler's supernova in low-energy (red), intermediate-energy (green) and high-energy (blue) X-rays. The background is an optical star field taken from the Digitized Sky Survey. The distance to the object is uncertain, with estimates ranging from 13,000 to 23,000 light-years, but recent studies favor the maximum range. This image spans 12 arcminutes, or about 80 light-years at the greatest distance. Credit: X-ray: NASA/CXC/NCSU/M.Burkey et al.; optical: DSS

University Park -- New detections of X-rays from a white-dwarf star that exploded as a supernova in 1604 will help astronomers to better understand the important class of stars known as "Ia supernovae," which are used to probe the distant universe.

"It is fascinating that we are still learning new things from one of the first supernova explosions of the modern astronomical era," said David Burrows, professor of astronomy and astrophysics at Penn State. Burrows is a member of the research team that made the discovery by detecting X-rays from the glowing remains of the exploded star using the Japan-led Suzaku satellite. The team discovered that the star had a greater fraction of heavy elements than the Sun. "These results were made possible by the high sensitivity and excellent energy resolution of Suzaku's X-ray Imaging Spectrometer (XIS)," Burrows said.

"Modern imaging X-ray spectrometers, similar to ones developed here at Penn State, have made it possible in recent years to make detailed measurements of the amounts of different elements produced in supernova explosions," Burrows said. These highly detailed measurements help astronomers to refine their our models of the explosion mechanisms in this important class of stars. "These new observations demonstrate the power of this experimental technique," Burrows said.

The scientists discuss their findings in a paper scheduled for publication in the 10 April 2013 issue of The Astrophysical Journal Letters.

The best way to explore the star's makeup is to perform a kind of post-mortem examination on the shell of hot, rapidly expanding gas produced by the explosion. By identifying specific chemical signatures in the supernova remnant, astronomers can obtain a clearer picture of the composition of the star before it blew up.

"The composition of the star, its environment, and the mechanism of the explosion may vary considerably among type Ia supernovae," said Sangwook Park, an assistant professor of physics at the University of Texas at Arlington and one of the leaders of the multi-institution research team. "By better understanding them, we can fine-tune our knowledge of the universe beyond our galaxy and improve cosmological models that depend on those measurements."

In 2011, astrophysicists from the United States and Australia won the Nobel Prize in Physics for the discovery that the expansion of the universe is picking up speed, a conclusion based on measurements of type Ia supernovae. An enigmatic force called dark energy appears to be responsible for this acceleration, and understanding its nature is now a top science goal. Recent findings by the European Space Agency's Planck satellite reveal that dark energy makes up 68 percent of the universe.

In addition to Penn State and the University of Texas, other institutions have scientists who were involved in this research, including the University of Pittsburgh, the University of Miyazaki in Japan, the University Politécnica de Catalunya in Spain, Los Alamos National Laboratory, Rutgers University, the Harvard-Smithsonian Center for Astrophysics, and the Korea Astronomy and Space Science Institute.

Launched on July 10, 2005, Suzaku was developed at the Japanese Institute of Space and Astronautical Science (ISAS), which is part of the Japan Aerospace Exploration Agency (JAXA), in collaboration with NASA and other Japanese and U.S. institutions.

[ Francis Reddy / Barbara K. Kennedy ]

CONTACTS

• David Burrows: burrows@astro.psu.edu

• Barbara Kennedy (PIO): 814-863-4682, science@psu.edu

PAPER

"A Super-Solar Metallicity for the Progenitor of Kepler's Supernova"
The Astrophysical Journal Letters (http://iopscience.iop.org/2041-8205/767/1/L10)
arXiv.org (http://arxiv.org/abs/1302.5435)

RELATED PRESS RELEASES

https://www.uta.edu/news/releases/2013/04/kepler-pub.php
http://chandra.harvard.edu/photo/2013/kepler/
http://www.nasa.gov/mission_pages/astro-e2/news/fossil-fireballs.html
http://www.nasa.gov/mission_pages/planck/news/planck20130321.html
http://www-history.mcs.st-and.ac.uk/Biographies/Kepler.html