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  • richardmitnick 12:19 pm on January 5, 2017 Permalink | Reply
    Tags: AAAS, , , Experts Seek to Boost Knowledge and Allies for Teaching STEM,   

    From AAAS: “Experts Seek to Boost Knowledge and Allies for Teaching STEM” 



    3 January 2017
    Kathleen O’Neil

    Multidisciplinary science organizations are working together to devise a plan for improving undergraduate STEM programs, calling for more collaboration across disciplines.industrieblick/Adobe Stock

    If you ever dropped differently-sized objects to see if one fell faster as part of your physics class, or watched a stalk of celery turn colors when placed in dye instead of listening to a lecture on capillary action, you have benefited from research into how students learn and understand science.

    Educational best practices that apply to all the fields of science recognize common observations, such as knowing that students tend to learn more from hands-on activities than a lecture. Yet, much more research is needed to frame more effective approaches to teaching science, technology, engineering or mathematics (STEM) topics with their complex and sometimes interlocking concepts.

    Discipline-based education research, however, has traditionally stayed in its respective STEM field, with separate journals, conferences and research topics and largely eschewed collaborative approaches that could better integrate teaching in the STEM fields.

    Now, a small group of researchers and organizations including AAAS and the Association of Public and Land-grant Universities (APLU), are trying to help break the knowledge their respective communities have free from such constraints. They aim to increase collaborations across disciplines by organizing a community of discipline-based education research (DBER) practitioners who want to improve undergraduate education across the STEM fields.

    About two dozen leaders in this area of STEM education research met 18-19 November in Washington, D.C. to discuss the potential goals and benefits of a cross-disciplinary community that they are calling the STEM DBER Alliance. It would supplement and enhance existing DBER group activities. The founders are working on a white paper and have plans to share their vision and solicit input more widely at other scientific and education meetings, including at the 2017 AAAS Annual Meeting in Boston in February.

    The nascent effort came about after several researchers, including Scott Franklin, a physics professor and director of a STEM education center at Rochester Institute of Technology, Charles Henderson, a physics professor at Western Michigan University, and Shirley Malcom, head of Education and Human Resources at AAAS, discussed forming a national interdisciplinary group at the public and land-grant universities’ group workshop in June.

    “It was quite clear that we needed an umbrella that was going to help us really understand how we could contribute to each other’s understanding,” Malcom said. “We said ‘Maybe we’re smarter together.’”

    Franklin said he and Henderson have seen the benefits of cross-discipline discussions at their own institutions and been interested in expanding it nationally. “We’ve seen firsthand the discussions that result from the very different experiences and backgrounds, and how these have supported research in unexpected directions,” Franklin said. He said the STEM DBER Alliance will bring him into contact with more researchers who can contribute ideas and opportunities for collaboration, and help the group tackle difficult issues, such as diversity, inclusion and broadening participation.

    Such collaborations could greatly help improve student retention and diversity in STEM fields, Malcom said. If a college student studying engineering is having trouble with the required mathematics, for example, it is not just a problem with how the engineering is taught, but rather how the math is taught, Malcom said. Engineering faculty could benefit greatly from learning how math educators teach those concepts and how students learn mathematical concepts.

    Sciences that deal with some of the same basic concepts could also begin to make those connections to help students better grasp fundamental principles. For example, students learn about energy in physics and biology, and whether the examples deal with colliding cars or sugar stored in plants, “it’s still energy,” said Susan Rundell Singer, lead editor of a 2012 National Academies of Science report on DBER.

    Singer combined biology DBER research with research on the developmental biology of flowering in plants in her 30 years as a professor at Carleton College before recently becoming vice president for academic affairs and provost at Rollins College in Winter Park, Florida.

    This kind of interdisciplinary teaching and education research is essential in preparing learners to address global challenges,, Singer said. “We need systems thinkers in engineering, biology, and chemistry to address climate change,” she said. “If we aren’t talking to each other and figuring out how these shared concepts are understood, then our students lose, and ultimately, our nation loses.”

    Efforts to improve science and mathematics education began in the early 1900s, when professors realized that traditional ways of teaching concepts to undergraduates could be improved. DBER had a resurgence in the 1960s post-Sputnik push to increase the number of STEM graduates. However, it was not until the 1990s that discipline-based education began to grow into an active research field in most STEM disciplines, with physics education research taking the lead.. It is now solidly established in each STEM field, with more faculty members being added each year.

    Singer hopes the cross-disciplinary community will “get people out of their STEM silos and talking with fields including economics and cultural anthropology, social psychology — not just to borrow their methodologies, but to think in new ways together.”

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
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  • richardmitnick 3:41 pm on December 28, 2016 Permalink | Reply
    Tags: AAAS, AAAS Reaches Out to Theology Students, , , Science for Seminaries program,   

    From AAAS: “AAAS Reaches Out to Theology Students” 



    Program Fosters Dialogue Between Scientific and Religious Communities

    20 December 2016
    Michaela Jarvis

    Participants in the Science for Seminaries program met for a curriculum meeting at the Jesuit School of Theology at Santa Clara University | AAAS/David Buller

    Many Americans turn to religious leaders with questions about science and its implications, yet clergy members often have little exposure to science in their training. AAAS has taken the lead, based on years of planning, in addressing this conundrum by organizing the Science for Seminaries program, with a pilot project launched in 2013. The pilot effort provided science resources for seminaries as they sought to equip future religious leaders with solid scientific information and with connections to scientists.

    The initial results are appreciable. One seminary professor, Bill Brown, reported a “dramatic rise” in students’ appreciation of science, describing activities associated with the project as “transformative.”

    Brown, the William Marcellus McPheeters Professor of Old Testament at Columbia Theological Seminary in Decatur, Georgia, elaborated on the most recent campus science events undertaken as part of the project. “We’ve had the best attendance yet among our students, followed by both formal and informal conversations. … In short, it seems that a sense of wonder about science is being cultivated on campus.”

    To most effectively connect with seminaries, AAAS partnered with the Association of Theological Schools, an accrediting association for graduate schools that train clergy. The pilot project, involving 10 seminaries representing a wide variety of Christian religious traditions, was designed to help professors incorporate relevant science into at least two of each seminary’s core courses. The participating schools also set out to organize at least one campus-wide event each to explore the relevance of science to theological education.

    By the most recent count at the close of the pilot project, more than 116 courses across the pilot schools had been revised, and at least 77 related events took place. Similarly, 137 applicants vied for 37 spots at related summer retreats designed to engage new seminary professors beyond those from the first 10 pilot schools. Perhaps most importantly, the project brought practicing scientists and seminary professors together to sculpt the most effective ways of conveying scientific advances and relevance to students.

    “We were pleasantly surprised by the wide range of science topics that seminaries chose to explore, including cosmology, genetics, neuroscience, paleontology, and more,” said Jennifer Wiseman, the director of the AAAS Dialogue on Science, Ethics, and Religion (DoSER) program, which led the effort. “We were also pleased by the large number of scientists who were eager to get involved with the program, by, for example, giving guest science lectures in seminary classrooms and developing relationships with seminary professors.”

    Last summer’s retreats brought together pilot project faculty and scientists with representatives of additional theological schools, providing a venue for sharing insights and strategies. After being introduced to Science for Seminaries at one of the retreats, Beth Rath, an assistant professor of philosophy, went back to Borromeo Seminary and offered a class called “What Does Science Prove?: Topics at the Intersection of Science and Religion.”

    One of the students who took the class, Andrew Karpinski, said it helped him develop a new understanding of the science of evolution, which he had learned in high school, though feeling somewhat dissatisfied with the totally secular discussion offered in school.

    “If you incorporate science into your religious education, you get the fullest picture of the world we live in,” said Karpinski, an aspiring religious leader who said he feels ready to incorporate science into his work with young people in inner-city Cleveland.

    Rath said Karpinski was among many in the class who came away with new insights.

    “This was the first time I’ve ever offered the course,” Rath said, “and it has been hugely successful. The impact that the class made on the students was more than I had hoped for.” Rath added that the retreat she attended put her in touch with neuroscientist Nancy Adleman, of the Catholic University of America, who helped Rath incorporate scientific articles into a unit on free will and moral responsibility.

    Others who attended have also begun incorporating science into their courses. Jim Higginbotham, associate professor of pastoral care and counseling at Earlham School of Religion, in Richmond, Indiana, has prepared a class on death and dying that will ask students to address the bioethical issues related to the end of life, to “create a critical dialogue” between the natural sciences and spirituality. Grace Kao, associate ethics professor at Claremont School of Theology, in Claremont, California, mentioned additions she will make to her Introduction to Christian Ethics course, such as discussing epigenetic alterations associated with war trauma for a session on war and peace, the science behind shopping and the ways that poverty can change your genes for a segment about economics, and an exploration of whether genes can predict a person’s liberalism and conservatism for a session on religion and politics. Steven Studebaker, associate professor of systematic and historical theology and the Howard & Shirley Bengal Chair in evangelical thought at McMaster Divinity College in Hamilton, Ontario, is planning on including in his Protestant theologians class John Polkinghorne, physicist and Anglican priest, and Philip Clayton, philosopher of religion and science. “The activities of the retreat cast a vision for what integrating science in the seminary classroom can look like,” Studebaker said.

    As students at the 10 seminaries who participated in the three-year pilot project experience the revised classes and campus-wide science-religion events, the schools continue to survey their reactions. The results have generally been extremely positive.

    At Multnomah Biblical Seminary in Portland, Oregon, most students responded that they strongly agreed or agreed with statements such as “I recognize that scientific discoveries might have a bearing on how I approach life, work, and ministry,” the surveys showed.

    In April, a two-day religion and science conference at Multnomah received rave reviews.

    “The conference was a refreshing example of dialogue, rather than war, between faith and science,” said Sara Mannen, Multnomah Master of Arts in Theological Studies student. “Recognizing our shared values of awe at the universe and desiring the good of society helped provide me with a starting point for conversations concerning faith and science.”

    Almost all of the students at Wake Forest University School of Divinity, in Winston-Salem, North Carolina, said they had enjoyed science education opportunities including public lectures by scientists such as cosmologist John Barrow and science field trips such as to the Kennedy Space Center, said Associate Professor of Christian Ethics Kevin Jung.

    Given the impact of the pilot Science for Seminaries project, DoSER is expanding the effort to assist seminaries, which is seen as an opportunity to affect public understanding and support for science — and the degree to which science can benefit society, a mission of AAAS.

    “There were many more interested seminaries and seminary professors that we could not accommodate in this initial pilot project,” said Se Kim, associate director of DoSER. “We’d like to provide science assistance for more seminaries and will also continue to help interested scientists get connected to seminaries interested in their scientific expertise.”

    In offshoots of the program, DoSER is now working with continuing education programs for active clergy at four institutions, and is assisting two Rabbinic training institutions with their efforts to incorporate science.

    Meanwhile, as the pilot seminaries build upon their initial efforts, they are sharing with other seminaries resources they have developed so far, such as revised syllabi, via the project website: scienceforseminaries.org. Additionally, AAAS has produced a series of discussion-provoking films for classroom use, called “Science: The Wide Angle.” The film series features 14 of the world’s leading scientists and three historians of science discussing exciting scientific advances — and their own wonder and amazement as they explore our world.

    As for enduring impact, Professor Jung quoted one of the Wake Forest students asked about the experience of exploring science as part of a religious education: “I think it will resonate for many years,” the student wrote, “as I continue to dig deeper into the issues of my congregants.”

    More information about the Science for Seminaries program, and the “Science: The Wide Angle” films, are available at the Science for Seminaries website.

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
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    Stem Education Coalition

  • richardmitnick 2:18 pm on October 26, 2016 Permalink | Reply
    Tags: AAAS, , Searching for Extraterrestrial Contact   

    From AAAS: “Searching for Extraterrestrial Contact” 



    21 September 2016
    Nathan Gilles

    Dr.Jill Taeter, SETI Institute

    Growing up in New York City, 8-year-old Jill Tarter had never experienced dark like it. She was in Florida. She had traveled to the Sunshine State only to experience a true absence of light, but the sky wasn’t dark at all. It was filled with bright, shining stars. As she walked along the beach with her father, the specks of flickering illumination feeding her imagination, Tarter experienced an insight that would define the rest of her life.

    Gazing upward, she asked herself: What if, revolving around one of those stars, was a planet much like Earth? And what if, on that planet there was a beach where a young creature walked with her father, watching the stars from her own galactic neighborhood? And what if, as this creature gazed and wondered, she glimpsed the light of a distant star around which a small planet revolved on which there was a beach where Tarter walked with her father, looking up and wondered: What if we’re not alone?

    “That became my worldview; that was just my mindset for as long as I can remember,” Tarter reflected.

    An AAAS Fellow since 2002, Tarter has spent the majority of her career in astronomy transmuting the wonder she felt on that beach into a systematic search for intelligent life elsewhere in our galaxy as head of the research arm of the Search for Extraterrestrial Intelligence Institute, better known as the SETI Institute.

    Beloved by many and disliked by others, the SETI Institute has for decades aimed radio telescopes at the sky in an effort to tease out potential signals of extraterrestrial origin from the cosmic noise of space. What became the SETI Institute began as independent scientific searches, eventually falling under a series of NASA programs until, in the mid-1990s, U.S. lawmakers cut the programs’ funding.

    However, the search endured. Tarter and other researchers associated with NASA’s SETI work created the nonprofit SETI Institute a decade earlier as a way to continue their search if public funding dissolved. When it did, Tarter and the Institute turned to private donations, mostly from Silicon Valley luminaries, such as Bill Hewlett and David Packard of Hewlett-Packard. During this time, Tarter became the most recognizable face of SETI, pitching the project’s science and philosophy to private philanthropists while honing SETI’s search techniques through overseeing the construction of new hardware and new computer algorithms. Her tenacity even earned her a place in pop culture history, when in 1981, her friend and colleague Carl Sagan based the protagonist of his science fiction novel Contact on her. The book was later made into a movie in 1997 staring Jodie Foster.

    “When Carl sent me a pre-publication copy of the book, I was flummoxed. There was so much in that character that was in common with my life,” said Tarter.

    A look at Tarter’s career shows the accolade from the iconoclastic Sagan was well-deserved.

    While her childhood experience on that Florida beach stuck with her into early adulthood, Tarter nonetheless began her career in science with an aspiration that was a little closer to home: “I wanted to go to the moon,” said Tarter.

    However, in the early 1960s, when she started her undergraduate program in engineering, science and engineering, let alone becoming an astronaut, were culturally off-limits for most women. So much so that Tarter found herself in the awkward position of being the only woman in a class of some 300 students. Nonetheless she excelled, and soon she began to stretch beyond engineering to astronomy, eventually earning her Ph.D. in the subject. It was around this time that she first waded into scientific controversy.

    In the mid-1970s, it was believed that there existed approximately 10 percent more mass in the Milky Way than could be accounted for by observations. Tarter proposed that some of this missing mass was due to a type of star that hadn’t yet been found. She believed these stars would not be massive enough to fuse hydrogen into helium, as our sun does. This meant they would be cool and, for all practical purposes, invisible to our instruments. She called these strange stars Brown Dwarfs.

    When she first proposed Brown Dwarfs, Tarter had a hard time convincing scientific publications that these small, cool stars existed. Meanwhile, the amount of missing mass grew in calculations, eventually being pinned largely on mysterious dark matter. Nonetheless, the idea of Brown Dwarfs caught on, and the first of what would be many Brown Dwarfs was discovered in the mid-1990s. Tarter was vindicated.

    “That was a lot of fun. That was a very enjoyable time,” said Tarter of the discovery.

    Tarter has yet to be vindicated in her search for extraterrestrial intelligence, but she hasn’t given up hope. Since SETI investigations began in the 1960s, only a miniscule portion of the night sky has been surveyed—the equivalent, by Tarter’s calculations, of taking a single glass of water from the world’s oceans. What’s more, as Tarter knows, searching for signals in space is complicated. Space as viewed through a radio telescope is a noisy place. Then there’s the fact that information-laden signals tend to look like noise at first glance. Add to this the multiple frequencies that could be used for broadcasting, the fact that all the sources of broadcast are in constant motion, and, most important, time—the time it takes for complex life to evolve, technological civilizations to develop, and the cosmic speed limit that is the speed of light—and you find yourself with a complex engineering problem.

    “After millennia of asking priests and philosophers what we should believe, suddenly we engineers and scientists have tools, telescopes and computers, to actually figure out what is,” said Tarter.

    Tarter’s first opportunity to apply her skills to the search for extraterrestrial intelligence came in the late 1970s. A colleague of hers wanted to do a search by piggybacking on a radio telescope, and he needed a computer programmer. Tarter just happened to be one of the few people who could program the computer he was using. The researchers’ plan was simple: Take recordings from the radio telescope using magnetic tape, then search the recordings using a computer algorithm programmed by Tarter. This is essentially how SETI still works.

    “Only we’ve now gone from 100 channels to 100 million channels. That’s been the progress that computing power has allowed us to achieve,” said Tarter.

    SETI, like other data-heavy endeavors, has benefited from the recent explosion in computing. This has allowed SETI to search for more complex and seemingly noisier signals. SETI’s hardware has also significantly improved, most notably on projects like the Allen Telescope Array, named after funder and Microsoft co-founder Paul Allen.

    Still, Tarter is realistic. Even with the best hardware and software there could be a lot of searching before we get pinged with a message from the stars, if one shows up at all. That’s because for two civilizations to talk they not only need to be close enough in space to discover one another but also close enough in the long history of our galaxy to overlap. But if they do overlap, that raises the possibility that technological civilizations might be sustainable in cosmic time, raising the further possibility that young civilization like ours could one day overcome the ecological and social upheavals our technologies have produced. This, says Tarter, as much as answering the question she first asked walking along that Florida beach is what should feed our collective imaginations.

    “If technologies pop up around the universe frequently, but in very short time they do themselves in or turn themselves off, then you are never going to get two technological civilizations that are coeval. But, if we know someone else has succeeded, that could be the motivation we need to help us find the solution to the problems that we’re facing,” said Tarter.

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
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  • richardmitnick 7:10 am on October 3, 2016 Permalink | Reply
    Tags: AAAS, , , Comet may have struck Earth just 10 million years after dinosaur extinction,   

    From AAAS: “Comet may have struck Earth just 10 million years after dinosaur extinction” 



    Sep. 28, 2016
    Paul Voosen

    A comet may have hit Earth 56 million years ago, leaving behind telltale glassy spheres in sediment cores. James Thew/iStockphoto

    Some 56 million years ago, carbon surged into Earth’s atmosphere, raising temperatures by 5°C to 8°C and causing huge wildlife migrations—a scenario that might mirror the world’s future, thanks to global warming. But what triggered this so-called Paleocene-Eocene thermal maximum (PETM) has remained a mystery.

    Now, in new work presented on 27 September here at the annual meeting of the Geological Society of America, a group of scientists bolsters its claim that a small comet impact kicked off the PETM, stirring up the carbon just 10 million years after a similar event decimated the dinosaurs. The group announced the discovery of glassy, dark beads, set in eight sediment cores tied to the PETM’s start—spheres that are often associated with extraterrestrial strikes.

    The critical evidence was hardly the result of a targeted campaign, according to Morgan Schaller, a geochemist at the Rensselaer Polytechnic Institute in Troy, New York, who presented the team’s work. The spheres were hiding in plain sight—in sediments off the coast of New Jersey.

    For a summer project, Schaller and Megan Fung, his graduate student and co-author, combed through the cores, looking for the fossils of microscopic organisms called foraminifera, often used as a dating tool. But instead of “forams,” they discovered a series of dark, glassy spheres. The spheres looked like microtektites, the debris created and tossed aside when comets or asteroids strike Earth at high speeds. This was a surprise to the team: These sediments had been studied many times before. The spheres may have blended against the background of the black trays that are commonly used to hunt for light-colored forams, as visible as a full moon in the night.

    The team is convinced the glassy spherules weren’t erupted from a volcano—another way they could have been made. Their water content is less than 0.03%, much lower than volcanic spheres, and they contain inclusions of the fused quartz glass that is characteristic of a hot impact. Their chemistry is different from microtektites from other known impacts. But the spheres will still face a high bar before being accepted as the real thing by other geologists.

    Separate work by Fung clinches the case for an impact, the team noted at the geology meeting. Three of the cores she examined had large spikes in charcoal immediately above (and, therefore, just after) the layers with the spheres. The charcoal, which contains signs of charred plants, points to widespread wildfires sparked by the impact, they said. PETM-associated sediments elsewhere in the world bear signs of similar charcoal events.

    The story may appear to be all wrapped up, but the group’s interpretation is misguided, says Jerry Dickens, an oceanographer at Rice University in Houston, Texas, who attended the talks. “They have completely misinterpreted the data and missed the correct, and more cool, story.” Dickens does not doubt that the spheres originated in an impact, or that the charcoal stemmed from forest fires. But both the spheres and charcoal were likely present throughout the PETM-associated clays, not just in small layers at the start. As the PETM got going, and erosion rates sped up in the warming world, sediments rich in carbon and oxygen accrued at faster rates at the New Jersey sites. This abundance of oxygen and carbon would have fueled microbes to degrade the charcoal and spheres, eliminating evidence for them higher up in a way that they couldn’t at the core’s base. This vanished evidence, he said, results “in a strange thing where they imagine a boundary horizon where it looks very important, but it’s not.”

    Others at the session were more convinced. “It is a really amazing discovery,” says Birger Schmitz, a geologist at Lund University in Sweden who also attended the talks. “The data look sound.” He says the evidence points to a small impact event of an asteroid or comet, maybe a body a couple kilometers across. However, similar objects hit Earth without triggering a global disturbance, he notes. “I have no idea of how a small asteroid could have triggered all the things that happened during the PETM.” To spark such a large carbon influx, the strike must have hit an unusual carbon-filled place like an oil reservoir, he says.

    News of the spherules has bounced around the community of PETM researchers for months, says Ellen Thomas, a geologist at Wesleyan University in Middletown, Connecticut. Thomas “absolutely” believes Schaller has found microtektites. But she is perplexed because she has since re-examined several different PETM cores from New Jersey and has not found any spherules; similarly, she has never seen them in global samples. If the team successfully dates the spherules to the start of the PETM, she will consider it real evidence of an impact. “If they have not dated them,” she says, “I think they may well be contamination.” The New Jersey cores were dug with rotary drills, and there’s abundant contamination in the samples, along with many spherules dating to impacts from different eras.

    If accepted, and that’s a big if, the strike could join a list of events associated with the PETM’s carbon injection. Many scientists believe the spike could have come from a chain reaction of events, starting with ocean volcanism cooking organic carbon out of rocks and into the atmosphere. Rising temperatures may have then released seafloor methane or thawed permafrost, driving up temperatures further.

    The scientists are cautious about how a small impact might fit in that chain of climate events—not all extraterrestrial strikes are the same. The PETM strike may have been a world-changing event like the dinosaur killer just 10 million years earlier. Or, it could have been like the object that struck and excavated the Chesapeake Bay 35 million years ago: locally devastating, but globally survivable.

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
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  • richardmitnick 2:23 pm on September 9, 2016 Permalink | Reply
    Tags: AAAS, , , , ,   

    From AAAS: “Scientists Build Giant Petri Dish to Film Bacteria Resistance” 



    8 September 2016
    Meagan Phelan

    Researchers have developed a large plate on which to film bacteria as they mutate in the presence of higher and higher concentrations of antibiotics, providing unprecedented insights into the phenomenon of antibiotic resistance.

    “Our device allows us to systematically map the different ways by which bacteria can become resistant to a range of antibiotics and antibiotic combinations,” said co-author Roy Kishony, a professor in the department of systems biology at Harvard Medical School and a principal investigator at Technion-Israel Institute of Technology.

    The ultimate goal, Kishony added, is to develop tools “that can predict the evolution of pathogens under different treatments, and better guide treatment choice.”

    “With our plate device, the evolutionary paths that the bacteria follow to achieve antibiotic resistance appear clearly and visually,” said co-author Michael Baym, a postdoctoral fellow in the Kishony Lab at Harvard Medical School, “and will hopefully let us start tailoring our approaches to treating resistance to different evolutionary modes.”

    The 2-by-4 foot petri dish used by the researchers to grow the bacteria contains nine bands at its base that can support varying concentrations of antibiotic. The results are reported in the 9 September issue of Science.

    Antibiotics have been used to treat patients since the 1940s, greatly reducing illness and death. However, these drugs have been used so frequently that the bacteria they are designed to kill have adapted to them in many cases, making the drugs less effective. At least 2 million people become infected with bacteria resistant to antibiotics each year in the United States, according to the Centers for Disease Control and Prevention, and at least 23,000 of these die as a result.

    “We know quite a bit about the internal defense mechanisms bacteria use to evade antibiotics,” Baym said, “but we don’t really know much about their physical movements across space as they adapt to survive in different environments.”

    To better understand how antibiotic resistance evolves in space and time, Baym and his colleagues developed a device called the microbial evolution growth arena plate, or MEGA-plate. The researchers used the antibiotics trimethoprim and ciprofloxacin in the MEGA plate in concentrations from zero to 10,000 times the original dose.

    On the right side of the plate where antibiotic levels were zero, Baym, Kishony, and colleagues grew Escherichia coli bacteria, which appeared white on the inky black background. Over two weeks, a camera mounted on the ceiling above the plate took periodic snapshots of the bacteria mutating.

    In the band with no antibiotic, the bacteria spread up until the point where they could no longer survive as they mingled with the first traces of antibiotic. Then, a small group of bacteria developed genetic mutations that allowed them to persist.

    Researchers traced the branching patterns of bacterial evolution on the MEGA plate. | Katharine Sutliff/ Science

    As these drug-resistant mutants arose, their descendants migrated to areas of higher and higher antibiotic concentration, developing further mutations to compete with other mutants around them. As they continued their journey to the highest antibiotic concentration level, all remaining bacterial mutants had to evolve further still.

    Through this process of cumulative, successive mutations, the researchers could visualize how bacteria that are normally sensitive to antibiotics can evolve resistance to extremely high concentrations — those up to 100,000-fold higher than the one that killed their predecessors — in just over ten days.

    The bacteria were unable to adapt directly from zero antibiotic to the highest concentrations, for both drugs tested, revealing that exposure to intermediate concentrations of antibiotics is essential for the bacteria to evolve resistance.

    Initial mutations at each new band on the plate led to slower growth, hinting that bacteria adjusting to the antibiotic aren’t able to grow at ideal speed while developing mutations. Once fully resistant, however, such bacteria regained normal growth rates.

    “One of our main objectives in the lab is to reveal such evolutionary tradeoffs,” said Kishony, “whereby a bacterium becoming resistant to a drug confers a cost we might be able to exploit. We might potentially use other drugs to enhance such resistance-associated weakness.”

    Intriguingly, the researchers also found that the location of bacterial species played a role in their success in developing resistance. For example, when the researchers moved the trapped mutants — those behind their fast-moving, fit counterparts — to the “frontlines” of the growing bacteria, they were able to grow into new regions where the frontline bacteria could not.

    “What we saw suggests that evolution is not always led by the most resistant mutants,” said Baym. “The strongest mutants are, in fact, often moving behind more vulnerable strains.”

    This overturns the assumption that mutants that survive the highest concentration of a drug drive the fitness of bacterial populations; rather, it is those mutants that are both sufficiently fit and arise sufficiently close to the advancing front that lead the evolutionary road.

    The work of Baym, Kishony, and colleagues was inspired by Hollywood wizardry, the authors say. Kishony saw a digital billboard advertising the 2011 film Contagion, a grim narrative about a deadly viral pandemic. The marketing tool was built using a giant lab dish to show hordes of painted, glowing microbes creeping slowly across a dark backdrop to spell out the title of the movie.

    “This project was fun and joyful throughout,” Kishony said. “Seeing the bacteria spread for the first time was a thrill. Our MEGA-plate takes complex, often obscure, concepts in evolution, such as mutation selection, lineages, parallel evolution and clonal interference, and provides a visual seeing-is-believing demonstration of these otherwise vague ideas. It’s also a powerful illustration of how easy it is for bacteria to become resistant to antibiotics.”

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

    Please help promote STEM in your local schools.
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    Stem Education Coalition

  • richardmitnick 6:04 pm on July 28, 2016 Permalink | Reply
    Tags: AAAS, , , , SESAME   

    From Science: “Physics lab aims to bridge political divides in Middle East” 



    Jul. 28, 2016
    Erik Stokstad

    Jordan is on the verge of opening the Synchrotron-light for Experimental Science and Applications in the Middle East as workers enter homestretch of synchrotron’s construction. CERN.

    An experiment in science diplomacy is on the threshold of success. Synchrotron-light for Experimental Science and Applications in the Middle East (SESAME), an $80 million synchrotron lab in Allan, Jordan, announced this week its first call for research that will be conducted on two beamlines expected to switch on this autumn. Research should start in earnest early next year.

    “The news is that it’s working, against the odds,” says Chris Llewellyn Smith, a physicist at the University of Oxford in the United Kingdom and president of the SESAME Council. The project was behind schedule because of political complications—visa restrictions for scientists, for example, and sanctions against Iran, a partner—and a freak snowstorm that collapsed the main building’s roof in 2013. Now, “we are in the final stage,” Eliezer Rabinovici, a theoretical physicist at Hebrew University of Jerusalem said at a 27 July press conference here at the EuroScience Open Forum. “To see dreams become reality, this is a very special moment.”

    A synchrotron is an important tool for many fields, as it creates intense beams of light that are used to probe biological cells or materials. There are about 60 synchrotrons in the world; SESAME is the first in the Middle East. Projects envisioned for the synchrotron include analyzing breast cancer tissue samples, studying Red Sea corals and soil pollution, and probing archaeological remains.

    The initiative was conceived in the 1990s as a partnership among many countries. Germany donated a big-ticket component: the injector that sends particles into the main storage ring. That project has attracted about $30 million in donations from outside the region, supplementing the construction costs financed primarily by Israel, Jordan, and Turkey. Iran has also pledged $5 million, but its contributions have been delayed by sanctions. SESAME’s operating costs are paid for by its member states: Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, the Palestinian National Authority, and Turkey.

    Smith says the facility is on track for commissioning in December. Two beamlines will be ready this year—for x-rays and infrared light—and two more will be built by 2019. Gihan Kamel, SESAME’s infrared beam line scientist, says researchers from the Middle East have already begun working at the facility, by hooking up detectors and microscopes to lower-power sources at the facility. Once the synchrotron fires up, the resolution and brightness will increase dramatically.

    In the conflict-riven Middle East, security at SESAME is a worry. “There are severe concerns,” Rabinovici says. The lab is building a guest house for visiting scientists inside its perimeter fence. Rabinovici hopes the physics oasis will help ease regional tensions. “We are offering light at the end of one tunnel.”

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 6:19 am on July 21, 2016 Permalink | Reply
    Tags: AAAS, , , Spring tides trigger tremors deep on California’s San Andreas fault   

    From Science: “Spring tides trigger tremors deep on California’s San Andreas fault” 



    Jul. 18, 2016
    Eric Hand

    Hundreds of thousands of tremors on the San Andreas fault are triggered by Earth’s tides. Ikluft/Wikimedia

    Things have been pretty quiet lately along the earthquake-prone San Andreas fault, where the grinding of tectonic plates is slowly shearing part of California off of North America. But 20 to 30 kilometers down, there’s a whole lot of shaking going on. Below the town of Parkfield, California, hundreds of thousands of slow microearthquakes called tremors go off routinely where Earth’s brittle crust gets weaker and softer. Now, scientists have shown that these tremors are triggered by the rhythmic pulsing of the tides: not just the twice-daily tides that occur as the moon revolves around Earth, but also the twice-monthly spring tides that occur when the sun and moon align and pull strongly on the planet. The finding gives scientists a new window into a deeper part of the San Andreas fault, and new insight into how stress builds up on small patches of the fault until they snap.

    “We’re finding out something about the loading rate on the faults and how fast this stress is accumulating on these patches,” says Nicholas van der Elst, a seismologist at the U.S. Geological Survey in Pasadena, California, and the lead author of the study.

    Stress builds up along the San Andreas fault as the Pacific plate tries to slip past the North American plate at a rate of several centimeters per year. But along most of the fault, the plates get jammed up and remain stuck until they reach a snapping point or are triggered to release the accumulated strain. Scientists have long wondered whether the tides could provide the proverbial straw. The tides not only slosh the oceans back and forth, but they also induce the shell of the solid earth to flex ever so slightly—sometimes in directions that happen to be aligned with faults.

    However, the tidal forces are incredibly weak in comparison with the forces that arise from the tectonic plate motions, and there are only a few confirmed examples of a connection between quakes and tides, mostly from deep faults underneath the edges of the oceans. That’s because in these regions, ocean sloshing forces add to the flexing of the earth, and water can lubricate and weaken faults. In 2002, scientists showed that tides triggered tremors on underwater volcanoes. And in 2004, scientists found that tidally triggered earthquakes could occur on some faults where ocean plates dive under continental plates. But for the most part, scientists have been unable to find a strong connection between tides and quakes on faults like the San Andreas—at least big quakes in the upper crust, says Eliza Richardson, a seismologist at Pennsylvania State University, University Park, who was not involved in the study. “In general there’s not a big, strong signal,” she says. “It’s considered elusive.”

    But as seismometers got more sensitive and were laid down in more places, scientists started to identify tremors in the lower crust. In these deeper regions, faults are weaker, and that means that tides can play a more important role. In 2012, scientists spotted deep tremors on the San Andreas fault below Parkfield that were tidally triggered, at the twice-a-day tidal peaks associated with the lunar day. In the new study, Van der Elst and his team found that bursts of tremors were also triggered during waxing of the twice-monthly spring tides, when the moon is aligned with the sun. Using a catalog of 4 million tremors that occurred between 2008 and 2015, they pinpointed the location and timing of the tremors in relation to the tides, they report today in the Proceedings of the National Academy of Sciences. Van der Elst says that the daily tidal peaks seem to trigger the littlest, deepest tremors, whereas the larger spring tide sets off larger patches of slip higher up.

    Richardson says that the study team has identified a transition zone between the upper crust, where big earthquakes go off on the rare occasions when there is slip, and the deep, soft crust, where the fault grinds along more quietly, through the slippage of nearly continuous little tremors. “There’s kind of a gradation,” she says. “These guys have figured out that there’s a class of these [tremors] that are shallower, and they behave differently than the ones that are a little deeper.”

    The tremors can’t predict the next “big one,” but in the long term, they could help scientists understand how big ones are set off. Some major earthquakes, such as the 2011 magnitude-9 Tohoku quake in Japan, are preceded by large “slow-slip events,” in which part of the fault moves quietly, without seismic notice, loading the fault to the point of rupture. Some scientists think that a burst of small tremors could signal a slow-slip event and imply that a big rupture is imminent. “We’re all waiting to see if the tremor pattern changes before or after a big earthquake,” Van der Elst says.

    See the full article here .

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  • richardmitnick 6:10 am on July 21, 2016 Permalink | Reply
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    From Science: “Better views of TB lungs may save lives and stop spread” 



    Jul. 19, 2016
    Jon Cohen

    A computed tomography scan of a tuberculosis patient’s lungs. Hanif Esmail

    High-tech images of the lungs of people with “latent” tuberculosis (TB) identified those at risk of developing symptoms. The new work, which researchers presented in a special TB session at the 21st International AIDS Conference being held in Durban, South Africa, this week, suggests new ways to evaluate whether treatment has cured an infection. But it could also upend the conventional wisdom that billions of people are walking around with dormant TB in their lungs that could one day erupt in full-fledged disease.

    “Active” TB kills an estimated 1.5 million people annually, but the World Health Organization (WHO) believes that fully one-third of the world’s population has latent TB, which means that Mycobacterium tuberculosis can’t be cultured from their sputum, but their immune cells still release interferon-gamma if mixed with pieces of the microbe. A skin test called “delayed type hypersensitivity” also is widely used to determine latency. Only about 10% of these people will develop TB at some point in their lives, and one of the big challenges in TB control is that there is no way to tell who is at risk. X-rays of latent patients’ lungs show nothing abnormal. WHO recommendations call for treating HIV-infected people who have latent TB with one drug, isoniazid, as a prophylaxis, but that’s often not done.

    In the new study, scientists used more sophisticated techniques to look at the lungs of 35 HIV-infected people from South Africa who had latent TB, according to the standard tests. One scan used computed tomography (CT), which shows the anatomy of the lung in far greater detail than an x-ray; the other is a positron emission tomography (PET) scan that uses an injection of radioactive glucose, which is taken up by metabolically active cells and indicates the presence of M. tuberculosis.

    Ten people had clear “hot” nodules in their lungs. “We saw pretty magnificent manifestations of disease,” says Clifton Barry, who heads TB research at the U.S. National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, and also has a lab at the University of Cape Town (UCT) in South Africa. (Barry’s team performed the work with Rob Wilkinson’s group at UCT.) The team saw no hot spots in the lungs of the other 25 patients.

    The researchers planned to put everyone in the study on isoniazid. But in the few weeks between the scans and when treatment began, four of the 10 patients with hot spots or abnormal CT scans developed TB symptoms, and M. tuberculosis showed up in the sputum of two others. In essence, the scans had revealed the people who were about to become sick and had a pressing need for the full-fledged TB treatment—three different drugs taken for 6 months. “The data are really compelling,” says David Russell, a TB researcher at Cornell University. “There’s nothing out there with that resolution.”

    The researchers continued to do lung scans during the treatment period, and they showed the lung abnormalities dissolving, which means they could use the technique to analyze treatment efficacy. “For many of us, this opened a new door of thinking about whether we really need to treat for six months,” says Jens Lundgren, an infectious disease specialist at the University of Copenhagen. “This is really a very exciting area for personalized medicine if we can separate those who can have a shorter period of treatment.” That would be welcome, because the standard regimen is a challenge for many patients.

    Although the TB in these 10 people was far from “latent,” Barry says, he is convinced that many, if not most, of the other 25 people, did not have any TB. He suspects they only had interferon gamma responses to M. tuberculosis because their immune systems had cleared the microbe at some time in the past. “It’s wrong to say that one third of the world has latent TB,” Barry says. “That number makes great starts for scientific papers but it’s totally misleading.”

    Lucica Ditiu, who leads the Stop TB Partnership, a nonprofit in Geneva, Switzerland, agrees that “latent” is not an accurate term. “These data are extremely interesting and something we should push forward,” Ditiu says.

    Unfortunately, CT and PET scans are very expensive, Barry acknowledges, and it would be impractical to screen the more than 2 billion people, most of them in poor countries, who meet the definition of latent TB. But the scans could be very useful in research, he says, for instance in early tests of new TB drugs to see which ones deserve large-scale efficacy studies. Wilkinson also found a possible alternative way to identify people with active infection. He did a so-called transcriptome analysis that compared the immune genes that were turned on in the 10 people who had hot spots and the 25 who did not. Six “biomarkers” surfaced that theoretically might identify those people who are most likely to develop symptomatic disease and transmit the infection. (Other labs recently have identified transcriptional biomarkers, too.)

    Barry notes that on average, each person who has an active M. tuberculosis infection transmits the pathogen to 10 others. “If we can identify people with subclinical disease before they transmit, that’s potentially a game-changer in terms of TB eradication,” he says.

    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 5:21 am on July 21, 2016 Permalink | Reply
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    From Science: “Attempt to explain away ‘dark energy’ takes a hit” 



    Jul. 19, 2016
    Adrian Cho

    A galaxy cluster as observed by the Canada-France-Hawaii telescope. Gravity from the cluster distorts the images of other galaxies in the background. L. Van Waerbeke and C. Heymans/CFHTLenS collaboration

    For nearly 20 years, physicists have known that the expansion of the universe has begun to speed up. This bizarre acceleration could arise because some form of mysterious dark energy is stretching space. Or, it could signal that physicists’ understanding of gravity isn’t quite right. But a new study puts the screws on a broad class of alternative theories of gravity, making it that much harder to explain away dark energy.

    The study is also path setting because it exploits an effect called weak lensing in which the gravity from closer galaxies distorts the images of more distant ones. “That’s the future,” says Bob Nichol, an observational cosmologist at the University of Portsmouth in the United Kingdom who was not involved in the study. “If you look to the next decade, there’s going to be an explosion of this data.”

    Physicists had expected the universe’s expansion to be slowing as the galaxies pull on one another with their gravity. But in 1998, two independent teams traced the history of the universe’s expansion by studying type 1a supernovae: stellar explosions whose colors tell when they went off and whose brightness reveals how far away they are now. Both teams found that the expansion is speeding up, suggesting that dark energy is blowing up the universe like a balloon.

    However, it’s possible that dark energy doesn’t exist and that the acceleration comes about instead because physicists’ understanding of gravity—Albert Einstein’s general theory of relativity—isn’t quite right. Einstein deduced that gravity arises because mass and energy warp spacetime. In general relativity, given the distribution of mass and energy, spacetime bends to minimize its curvature, denoted R. But in so-called f(R) (pronounced “eff-of-are”) theories, spacetime contorts to minimize the curvature plus some extra function of the curvature. That change produces an extra gravitylike force that can either attract or repel under different conditions.

    In 2007, theorists Wayne Hu of the University of Chicago in Illinois and Ignacy Sawicki, now at the University of Geneva in Switzerland, showed that, with the right choice of the function f(R), such a theory might explain the accelerating expansion without dark energy. To do that, the extra force has to disappear where gravity is relatively strong, such as within a galaxy or the early universe, and kick in on the largest scales and at later times.

    This map shows the distribution of matter—dark and ordinary—deduced through weak lensing. Cosmologists used such a map to test an alternate theory of gravity. Van Waerbeke, Heymans/CFHTLenS

    To test such theories, scientists must study the universe on huge scales. Last year, Nichol and colleagues tested f(R) theory by tallying galaxy clusters spanning millions of light-years. If dark energy is stretching space, then it should slow the formation of massive clusters and produce fewer of them than f(R) gravity would. Nichol and colleagues found numbers consistent with dark energy. The analysis is tricky, however. Researchers need to estimate the mass of each cluster, which comes mostly from mysterious, invisible dark matter. So Nichol and colleagues inferred a cluster’s mass from x-rays coming from hot gas within it, relying on theoretical modeling of the interplay of ordinary and dark matter.

    Now, a team of scientists led by Zuhui Fan, an astronomer at Peking University in Beijing, has taken an approach that measures a cluster’s mass directly. Gravity from a massive object can distort the images of things beyond it. A galaxy cluster thus distorts the images of more distant galaxies, so that instead of being oriented randomly in the sky, their elongated shapes align slightly, like fish in a school. The strength of that “weak lensing” directly reveals the mass of the foreground cluster. “You don’t rely on the scaling between the cluster’s mass and its [ordinary matter] content,” says Baojiu Li, a cosmologist at Durham University in the United Kingdom, who worked on the study.

    The researchers used data from the 3.6-meter Canada-France-Hawaii Telescope on Mauna Kea in Hawaii, which imaged 5.5 million galaxies to create a weak lensing map covering 154 square degrees of sky. From the “peaks” in the map, they tallied clusters weighing hundreds of times much as our Milky Way galaxy, they report in a paper in press at Physical Review Letters. Those tallies agree with the predictions of dark energy and weaken the case for f(R) theories.

    CFHT Telescope, Mauna Kea, Hawaii, USA
    CFHT Interior
    CFHT Telescope, Mauna Kea, Hawaii, USA

    “At the moment, this is the best measurement on the cosmological scale,” Nichol says. The new result doesn’t quite kill f(R) theory, but if the limit on a key parameter can be lowered by another factor of 10, Nichol says, “I suspect that people will say, ‘This theory is not it.'”

    However, Hu questions how far the method can be pushed. Testing f(R) gravity further may require accounting for the detailed distribution of dark matter within individual clusters, he says. But that distribution will be modified by the interplay between dark and ordinary matter, Hu says, bringing the issue back into play.

    Still, experts say, the new work shows the potential to probe the cosmos with weak lensing. The Large Synoptic Survey Telescope, under construction in Cerro Pachón, Chile, will map weak lensing over 20,000 square degrees—roughly half the sky. The European Space Agency’s proposed Euclid spacecraft and NASA’s proposed Wide Field Infrared Survey Telescope satellite [WFIRST] will employ the technique. “In terms of data quality,” Li says, “there’s going to be a big improvement from what we have now.”

    LSST telescope, currently under construction at Cerro Pachón Chile
    LSST telescope, currently under construction at Cerro Pachón Chile

    ESA/Euclid spacecraft
    ESA/Euclid spacecraft


    See the full article here .

    The American Association for the Advancement of Science is an international non-profit organization dedicated to advancing science for the benefit of all people.

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  • richardmitnick 7:19 am on July 18, 2016 Permalink | Reply
    Tags: AAAS, , , ,   

    From UCSD via Science: “These disaster machines could help humanity prepare for cataclysms” 



    UC San Diego bloc

    Jul. 14, 2016
    Warren Cornwall

    The “Wall of Wind” at Florida International University in Miami can blow as fiercely as a category-5 hurricane. Robert Sullivan

    For the past year, Tara Hutchinson has been trying to figure out what will happen to a tall building made from thin steel beams when “the big one” hits.

    To do that, she has erected a six-story tower that rises like a lime-green finger from atop a shrub-covered hill on the outskirts of San Diego, California. Hundreds of strain gauges and accelerometers fill the building, so sensitive they can detect wind gusts pressing against the walls. Now, Hutchinson just needs an earthquake.

    In most of the world, this would be a problem. Even here, where a major fault runs right through downtown, the last quake of any note struck 6 years ago and was centered in nearby Mexico. But Hutchinson, a structural engineering professor at the University of California (UC), San Diego, doesn’t need plate tectonics to cooperate. This summer she has an appointment at one of the world’s biggest earthquake machines.

    6 Story CFS Load Bearing Project Downtown Los Angeles – Wilshire Vermont (Topping out Roof). http://nheri.ucsd.edu/projects/2016-light-gauge-cold-steel-buildings/

    This device—a sort of bull ride for buildings—is one in a network built around the United States over the past 15 years to advance natural disaster science with more realistic and sophisticated tests. Costing more than $280 million, the National Science Foundation (NSF) initiative has enabled scientists to better imitate some of the most powerful and destructive forces on Earth, including earthquakes, tsunamis, and landslides.

    The work has led to new building standards and better ways to build or retrofit everything from wharves to older concrete buildings. Scientists have gained insights into how quakes damage pipes in walls and ceilings and how to help quake-proof highway ramps, tall steel buildings, parking garages, wooden homes, and brick walls, to name a few.

    That expansion continues today. In a new $62 million, 5-year program, the network of doomsday machines is expanding to simulate hurricanes and tornadoes and is joining forces with computer modeling to study how things too big for a physical test, such as nuclear reactors or an entire city, will weather what Mother Nature throws at them.

    Scaling down disasters

    Credit California’s Northridge earthquake for helping set this in motion. The 1994 quake, centered near Los Angeles, killed 72 and cost an estimated $25 billion in damages. In its aftermath, a report commissioned by Congress warned that the country needed a more systematic approach to studying how to reduce damage from earthquakes. NSF responded with the $82 million Network for Earthquake Engineering Simulation. The money funded a construction spree at 14 sites around the country. Another $200 million paid for operating the sites through 2014. That included UC San Diego, which unveiled the world’s largest outdoor shake table in 2004.

    A building awaits its ordeal on the shake table at the University of California, San Diego. Erik Jepsen/UC San Diego

    Researchers at Oregon State University, Corvallis, unleash tsunamis in a wave basin. © Aurora Photos/Alamy Stock Photo

    Descriptions of these disaster labs are often couched in superlatives: the biggest, the longest, the most powerful. In addition to the San Diego facility, the projects funded under the original program and its successor, the Natural Hazards Engineering Research Infrastructure (NHERI), include North America’s largest wave flume for studying tsunamis at Oregon State University, Corvallis; the world’s largest university-based hurricane simulator at Florida International University in Miami; and, at UC Davis, the world’s biggest centrifuge for making scale models mimic the stresses on tons of buildings, rock, and dirt—crucial information for assessing how structures will weather earthquakes and landslides.

    More than bragging rights is at stake. When it comes to learning how buildings cope with the forces generated in a natural disaster, size often does matter. For example, the way soil particles stick together, an important factor in landslide risks, depends on how much mass is pushing down on them. Similarly, it’s nearly impossible to build accurate, tiny versions of rebar: steel rods embedded in concrete structures that are critical to building performance. Similar difficulties arise with measuring how hurricane-force winds interact with a building.

    “You can’t take a real building and scale it down to one-tenth and put it in a wind tunnel. The physics doesn’t work,” says Forrest Masters, a wind engineer at the University of Florida in Gainesville who directs his university’s share of NHERI. That includes a machine capable of subjecting 5-meter-tall walls to the air pressures found in a 320-kilometer-per-hour hurricane, and a wind tunnel whose floor can be modified to see how different terrain influences the way wind interacts with structures.

    Computer models too can fall short in accurately reproducing all the forces at play as, say, a bridge twists and sways in an earthquake. So many different pieces in the bridge are pulled in so many directions at once that it can fail in unpredictable ways, causing models to misrepresent reality. In 2010, a contest at the San Diego shake table pitted 41 teams of experts running models against a real-life test of a 7-meter-tall bridge column topped with 236 metric tons of concrete blocks. The computer results were all over the place, says Stephen Mahin, a structural engineer at UC Berkeley who helped orchestrate the event. On average, they underestimated how much the column would sway by 25%. “You can’t quite trust the computer results yet,” Mahin says.

    One morning in mid-May, Hutchinson inspects her building in the final stages of preparation for the test. She points to tiny gaps that have sprung open where metal ceiling joists meet the wall in a first-floor room. That happened during a minor, preliminary shake her team delivered to the building a day earlier. It’s the kind of thing that could make a difference in how load is shared between pieces of the building, and how much damage the building suffers in the next temblor. And it wouldn’t show up in a computer model.

    “You’re not going to account for every screw,” she says. “Look at how subtle this damage is.”

    Shake, rattle, and roll

    Devising a machine that can pack the same wallop as a magnitude-8.0 earthquake or a category-5 hurricane isn’t easy, or cheap. A look under the hood of San Diego’s shake table illustrates the kind of mechanical muscle needed. Joel Conte, an engineering professor who oversees the shake table operations, leads the way into a cavernous under-ground room filled with machinery. A 20,000- liter metal tank holds the hydraulic fluid that drives the entire system. Two pumps slurp the fluid from there into a bank of 50 slender black cylinders reminiscent of street light poles at pressures reaching 34,000 kilopascals (5000 pounds per square inch). That high pressure is crucial, generating enough force to swiftly move an entire building.

    Conte turns down a passageway, tracing the path of the fluid through steel pipes 30 centimeters across, and into a room dominated by a mass of steel resembling the hull of a flat-bottomed boat. This is the epicenter. A metal plate 5 centimeters thick, 12 meters long, and nearly 8 meters wide sits overhead, bolted to the steel underbelly. At either end, an actuator that looks something like a car’s shock absorber, but is as thick as a man’s torso, extends from this structure to the concrete wall. When the commands come from computers in a nearby building, the actuators will jerk to life, the hydraulic fluid driving them back and forth. The plate, pushed and pulled between them, will slide across metal sheets polished mirror-smooth at speeds of up to 1.8 meters per second. Voilà! Instant quake.

    “The real world, you cannot count on it,” Conte says. “You cannot say, ‘Oh, I’m going to sit and wait for the next earthquake in front of this big building, and I’m going to invest a lot in sensors.’ You may have to wait 30, 40, 50 years. So you produce an earthquake.”

    Since its construction for $10 million, the shake table has tested a four-story concrete parking garage, a wind turbine, and a five-story concrete building complete with elevator and stairs, among other things. The tests have shown that special inserts can increase resilience by allowing a building to move over its foundation and that modular concrete floors can behave erratically unless they have additional reinforcement. They have also revealed how tall, wood-framed buildings fail and how reinforcements can strengthen old brick buildings.

    Back in his office, Conte gleefully clicks through the “best of” video highlights. A four-story wood building twists and splinters to the ground. A parking garage teeters back and forth like a rocking chair. A split screen shows two identical rooms filled with hospital beds and medical equipment. One is in a building outfitted with padded foundations that help it absorb an earthquake’s shock; the other isn’t. As the video runs, beds in the regular building suddenly lurch back and forth before toppling over. In the other, they barely move.

    In the current test, Hutchinson wants to see how a building six stories tall made from lightweight steel performs during and after an earthquake. She thinks it could do well, partly because it’s lighter than a concrete building of the same height, giving it less mass to generate damaging forces during a quake. Today, building codes allow this type of construction to be just shy of 20 meters tall. But the tallest building really put to the test was only two stories high.

    The structure, modeled after an apartment building, is destined for a multistage torture test. Hutchinson and her colleagues will first put it through a simulation of several quakes, including Northridge and a 2010 magnitude-8.8 in Chile. Then they will set fires in parts of the building to see how it holds up in a blaze triggered by quake damage. Then they will shake the building again in a mock aftershock, hard enough that it might collapse.

    The results aren’t just of academic interest. Sponsors of the test include manufacturers of the steel construction parts, the insurance industry, and state government. “There’s nothing like a full-scale test,” says Richard McCarthy, executive director for the Cali–fornia Seismic Safety Commission in Sacramento, a government commission that advises policymakers. It contributed $100,000 to the event, he says, partly with an eye toward potential changes to building codes governing construction using these materials.

    Conte is now lobbying state officials for a $14 million upgrade that would allow the machine to run even more realistic tests. Right now it can move only back and forth in two directions; new hardware would add up-and-down, side-to-side, and diagonal motions, enabling it to move in every direction—like the world’s biggest shake table, an indoor facility in Miki, Japan.

    Up next: Hybrid simulations

    Scientists are trying to go even bigger by marrying such physical tests with computer models. The resulting “hybrid” simulations can test massive structures too big to fit inside any test facility, says James Ricles, a civil engineer at Lehigh University in Bethlehem, Pennsylvania. His lab, which is part of the NSF network, tests well-understood parts of a structure with computer models but stages physical tests for parts that the models can’t handle. In a feedback loop measured in milliseconds, sensors from the physical test send data to the model, which adapts and sends new signals that tell the machines driving the physical test how to tweak their next moves.

    Ricles’s lab simulated the behavior of an elevated highway during an earthquake by physically testing the concrete columns while testing a virtual model of the bridge deck in a computer. He recently applied the same strategy to testing a design meant to allow a steel building to rock back and forth rather than bend during a quake. A four-story chunk of the building stood in the lab; the rest of it existed only in the microprocessors of a computer.

    Destruction is a definite part of the work’s appeal, says Gilberto Mosqueda, an engineering professor who runs hybrid tests at UC San Diego: “You build these models, and essentially you shake them till you break them.” But the mountains of data generated by the tests also open the way to more sophisticated numerical models that could one day do some of the work of the doomsday machines.

    Whereas the earlier NSF program focused on big testing platforms, the NHERI initiative is putting more money into the virtual side. The University of Texas, Austin, won $13.7 million to build a data repository and software platform to store information from years of field tests. In the future, engineers should be able to tap data in the digital repository to boost the accuracy of their computer models. And NSF will soon issue an $11 million award for a computational modeling and simulation center.

    “Will we get to the point where we can just model everything and have confidence? That may still be a long way off,” says Joy Pauschke, a structural engineer and director of the NSF program that funds the testing work in Arlington, Virginia. “But hopefully as we test and improve models, we start moving towards having better capabilities with the computational modeling.”

    Berkeley’s Mahin—whose 2010 contest exposed the shortcomings of models—now also foresees bright prospects for modeling. Advances in machine learning and cloud computing, he predicts, will lead to models capable of simulating not just single buildings but entire communities. Unleashing “virtual disasters” could then enable researchers and government officials to grasp the region-wide effects of a major quake or storm and decide which measures today would prevent the most damage.

    “In 20 years, you can model a whole city in a very complicated way, I think,” Mahin says. “There’s a great hope this analysis can help mitigate the damage from future natural disasters.”

    See the full article here .


    Earthquake and Post-Earthquake Fire Performance of Mid-Rise Light-Gauge Cold-Formed Steel Framed Buildings

    Abstract: Light-gauge cold-formed steel (CFS) framed multi-story residential housing has the potential to support societies urgent need for low cost, multi-hazard resilient housing. CFS-framed structures offer lower installation and maintenance costs, are durable, ductile, lightweight, and manufactured from recycled materials. In addition, consistency in material behavior and low material costs are added benefits compared with their wood-framing counterparts. The components of CFS-framed assemblies (studs, track, joists) can be assembled quickly and with relative ease into prefabricated panels. Notably, the ductile nature of a CFS-framed structure aligns with the performance needs in moderate to high seismic zones. Compared to other lightweight framing solutions (such as timber), CFS is non-combustible, an important basic characteristic to prohibit fire spread. Taken in totality, these many beneficial attributes lead to a highly sustainable infrastructure for housing communities.

    This research aims to evaluate the earthquake and post-earthquake fire performance of mid-rise CFS-building systems through full-scale earthquake and live thermal testing of a 6-story wall-braced system. Through partnership with cold-form steel and other materials suppliers, design engineers, and insurance entities, a unique experimental program is underway. Central to this effort is the construction of a full-scale portion of a 6-story CFS-wall braced building directly on the UCSD Large High Performance Outdoor Shake Table. Wall and floor systems for the building are assembled in a panelized fashion off-site, thus the overall erection time of the building is dramatically reduced. The test building will be subjected to low amplitude white noise motions and sequentially increasing in amplitude earthquake motions. Subsequently, live thermal tests will be conducted on two floors of the building, in corridor and room like spaces strategically designed to investigate thermal patterns that develop due to reduced compartmentation ensued during the earthquake motions.


    Prof. Tara Hutchinson (PI)
    Prof Gil Hegemeir (Co-PI)
    Dr. Xiang Wang (Post-Doctoral Researcher)
    Mr. Srikar Gunisetty (Graduate Student) [UC San Diego]
    Prof. Brian Meacham [WPI]
    Dr. Praveen Kamath [WPI]

    Department of Housing and Urban Development, California Seismic Safety Commission, and more than 10 industry sponsors (see: http://cfs-research.ucsd.edu)

    See this full article here .


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