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  • richardmitnick 12:57 pm on February 10, 2020 Permalink | Reply
    Tags: "Where math meets physics", , , , Penn Today,   

    From Penn Today: “Where math meets physics” 


    From Penn Today

    February 7, 2020
    Erica K. Brockmeier
    Eric Sucar, Photographer

    Collaborations between physicists and mathematicians at Penn showcase the importance of research that crosses the traditional boundaries that separate fields of science.

    1
    Penn is home to an active and flourishing collaboration between physicists and mathematicians. Advances in the fields of geometry, string theory, and particle physics have been made possible by teams of researchers, like physicist Burt Ovrut (above), who speak different “languages,” embrace new research cultures, and understand the power of tackling problems through an interdisciplinary approach.

    In the scientific community, “interdisciplinary” can feel like an overused, modern-day buzzword. But uniting different academic disciplines is far from a new concept. Math, chemistry, physics, and biology were grouped together for many years under the umbrella “natural philosophy,” and it was only as knowledge grew and specialization became necessary that these disciplines became more specialized.

    With many complex scientific questions still in need of answers, working across multiple fields is now seen an essential part of research. At Penn, long-running collaborations between the physics and astronomy and the math departments showcase the importance of interdisciplinary research that crosses traditional boundaries. Advances in geometry, string theory, and particle physics, for example, have been made possible by teams of researchers who speak different “languages,” embrace new research cultures, and understand the power of tackling problems through an interdisciplinary approach.

    A tale of two disciplines

    Math and physics are two closely connected fields. For physicists, math is a tool used to answer questions. For example, Newton invented calculus to help describe motion. For mathematicians, physics can be a source of inspiration, with theoretical concepts such as general relativity and quantum theory providing an impetus for mathematicians to develop new tools.

    But despite their close connections, physics and math research relies on distinct methods. As the systematic study of how matter behaves, physics encompasses the study of both the great and the small, from galaxies and planets to atoms and particles. Questions are addressed using combinations of theories, experiments, models, and observations to either support or refute new ideas about the nature of the universe.

    In contrast, math is focused on abstract topics such as quantity (number theory), structure (algebra), and space (geometry). Mathematicians look for patterns and develop new ideas and theories using pure logic and mathematical reasoning. Instead of experiments or observations, mathematicians use proofs to support their ideas.

    While physicists rely heavily on math for calculations in their work, they don’t work towards a fundamental understanding of abstract mathematical ideas in the way that mathematicians do. Physicists “want answers, and the way they get answers is by doing computations,” says mathematician Tony Pantev. “But in mathematics, the computations are just a decoration on top of the cake. You have to understand everything completely, then you do a computation.”

    This fundamental difference leads researchers in both fields to use the analogy of language, highlighting a need to “translate” ideas in order to make progress and understand one another. “We are dealing with how to formulate physics questions so it can be seen as a mathematics problem” says physicist Mirjam Cvetič . “That’s typically the hardest part.”

    3
    Kamien works on physics problems in that have a strong connection to geometry and topology and encourages his students to understand problems as mathematicians do. “Understanding things for the sake of understanding them is worthwhile, and connecting them to things that other people know is also worthwhile,” he says.

    “A physicist comes to us, asks, ‘How do you prove that this is true?’ and we immediately show them it’s false,” says mathematician Ron Donagi. “But we keep talking, and the trick is not to do what they say to do but what they mean, a translation of the problem.”

    In addition to differences in methodology and language, math and physics also have different research cultures. In physics, papers might involve dozens of co-authors and institutions, with researchers publishing work several times per year. In contrast, mathematicians might work on a single problem that takes years to complete with a small number of collaborators. “Sometimes, physics papers are essentially, ‘We discovered this thing, isn’t that cool,’” says physicist Randy Kamien. “But math is never like that. Everything is about understanding things for the sake of understanding them. Culturally, it’s very different.”

    Mind the gap

    When asked how mathematicians and physicists can bridge these fundamental gaps and successfully work together, many researchers refer to a commonly cited example that also has a connection to Penn. In the 1950s, Eugenio Calabi, now professor emeritus, conjectured the existence of a six-dimensional manifold, a topological space arranged in a way that allows complex structures to be described and understood more simply. After the manifold’s existence was proven in 1978 by Shing-Tung Yau, this new finding was poised to become a fundamental component of a new idea in particle physics: string theory.

    Proposed in the 1970s as a candidate framework for a “theory of everything,” it describes matter as being made of one-dimensional vibrating strings that form elementary particles, like electrons and neutrinos, as well as forces, like gravity and electromagnetism. The challenge, however, is that string theory requires a 10-dimensional universe, so physicists turned to the Calabi-Yau manifolds as a place to house the “extra” dimensions.

    Because the structure is so complex and only recently proven by mathematicians, it wasn’t simple to directly implement into a physics framework, even though physicists use math all of the time in their work. Physicists “use differential geometry, but that’s been known for a long time,” says physicist Burt Ovrut. “When all of a sudden string theory launches, who the heck knows what a Calabi-Yau manifold is?”

    Through the combined efforts of Ed Witten, a physicist with strong mathematical knowledge, and mathematician Michael Atiyah, researchers found a way to apply Calabi-Yau manifolds in string theory. It was the ability of Witten to help translate ideas between the two fields that many researchers say was instrumental in successfully applying brand-new ideas from mathematics into up-and-coming theories from physics.

    At Penn, mathematicians, including Donagi, Pantev, and Antonella Grassi, and physicists Cvetič , Kamien, Ovrut, and Jonathan Heckman have also recognized the importance of speaking a common language as they work across the two fields. They credit Penn as being a place that’s particularly adept at fostering connections and bridging gaps in cultural, linguistic, and methodological differences, and they credit their success to time spent listening to new ideas and developing ways to “translate” between languages.

    For Donagi, it was a chance encounter with Witten in the mid 1990s that led the mathematician to his first collaboration with a researcher outside of pure math. He enjoyed working with Witten so much that he reached out to Penn physicists Cvetič and Ovrut to start a “local” crossover collaboration. “I’ve been hooked since then, and I’ve been talking as much to physicists as to other mathematicians,” Donagi says.

    During the mid-2000s, Donagi and Ovrut co-led a math and physics program with Pantev and Grassi that was supported by the U.S. Department of Energy. The collaboration marked a successful first official math and physics crossover collaboration at Penn. As Ovrut explains, the work was focused on a specific kind of string theory and required extremely close interactions between physics and math researchers. “It was at the very edge of mathematics and algebraic geometry, so I couldn’t do this myself, and the mathematicians were very interested in these things.”

    Cvetič, a longtime collaborator with Donagi and Grassi, says that Penn’s mathematicians have the expertise they need to help answer important questions in physics and that their collaborations at the interface of string theory and algebraic geometry are “extremely fruitful and productive.”

    “I think it’s been incredibly productive and helpful for both our groups,” Donagi says. “We’ve been doing this for longer than anyone else, and we have a really good strong connection between the groups. They’ve almost become one group.”

    3
    “What facilitates this type of research is that we can talk to the physicists,” says Pantev (right), who has worked for many years with Cvetič and Donagi. “When we go talk to them, they know how to speak our language, and they can explain the questions they are struggling with in a way that we can understand and approach them.”

    And in terms of embracing cultural differences, physicists like Kamien, who works on problems with a strong connection to geometry and topology, encourages his group members to try to understand math the way mathematicians do instead of only seeing it as a tool for their work. “We’ve tried to absorb not just their language but their culture, how they understand things, how sometimes understanding a problem more deeply is better,” he says.

    Crossing paths

    Craig Lawrie and Ling Lin, a current and former postdoc working with Cvetič and Heckman, know firsthand about both the challenges and opportunities of working on a problem that combines both cutting-edge math and physics. Physicists like Lawrie and Lin, who work in M-theory and F-theory, are trying to figure out what types of particles different geometric structures can create while also removing the “extra” six dimensions.

    Adding extra symmetries makes string theory problems easier to work with and allows researchers to ask questions about the properties of geometric structures and how they correspond to real-world physics. Building off previous work by Heckman, Lawrie and Lin were able to extract physical features from known geometries in five-dimensional systems to see if those particles overlapped with standard model particles. Using their knowledge of both physics and math, the researchers showed that geometries in different dimensions are all related mathematically, which means they can study particles in different dimensions more easily.

    Using their physics intuition, Lawrie and Lin were able to apply their knowledge of math to make new discoveries that wouldn’t have been possible if the two fields were used in isolation. “What we found seems to suggest that theories in five dimensions come from theories in six dimensions,” explains Lin. “That is something that mathematicians, if they didn’t know about string theory or physics, would not think about.”

    Lawrie adds that being able to work directly with mathematicians is also helpful in their field since understanding new math research can be a challenge, even for theoretical physics researchers. “As physicists, we can have a long discussion where we use a lot of intuition, but if you talk to a mathematician they will say, ‘Wait, precisely what do you mean by that?’ and then you have to pull out your important assumptions,” says Lawrie. “It’s also good for clarifying our own thought process.”

    Rodrigo Barbosa also knows what it’s like to work across fields, in his case coming from math to physics. While studying a seven-dimensional manifold as part of his Ph.D. program, Barbosa connected at a conference with Lawrie over their shared research interests. They were then able to combine their experiences through a successful interdisciplinary collaboration [Physical Review D], work that was motivated by Barbosa’s Ph.D. research in math that included both junior and senior faculty as well as postdocs and graduate students from physics.

    While Barbosa says that the work was challenging, especially being the only mathematician in the group, he also found it rewarding. He enjoyed being able to provide mathematical explanations for certain difficult concepts and relished the rare opportunity to work so closely with researchers outside of his field while still in graduate school. “I’m very grateful that I did my Ph.D. at Penn because it’s really one of a handful of places where this could have happened,” he says.

    The next generation

    Faculty in both departments see the next generation of students and postdocs as “ambidextrous,” having fundamental skills, knowledge, and intuition from both math and physics. “Young people are extremely sophisticated and open minded,” says Pantev. “In the old days, it was very hard to get into physics-related research if you were a mathematician because the thinking is completely different. Now, young people are equally versed in both modes of thinking, so it’s easy for them to make progress.”

    4
    Heckman joined the physics faculty in 2017 and is already active in a number of collaborations with the math department. “What makes this place so great is that we’re talking a common language,” he says. “Although Ron says we sometimes speak with an accent.”

    Heckman is also a member of this new ambidextrous generation of researchers, and in his two years at Penn he has co-authored several papers and started new projects with mathematicians. He says that researchers who want to be successful in the future need to be able to balance the needs of both fields. “Some students act more like mathematicians, and I have to guide them to act more like physicists, and others have more physical intuition but they have to pick up the math,” he says.

    It’s a balance that requires a blend of flexibility and precision, and is one that will be a continuing challenge as topics become increasingly complex and new observations are made from physics experiments. “Mathematicians want to make everything well-defined and rigorous. From a physics perspective, sometimes you want to get an answer that doesn’t need to be well-defined, so you need to make a compromise,” says Lin.

    This compromise is something that’s attracted Barbosa to working more with physicists, adding that the two fields are complementary. “Problems have become so difficult that you need input from all possible directions. Physics works by finding examples and describing solutions, while in math you try to see how general these equations are and how things fit together,” Barbosa says. He also enjoys that physics provides him with a way to make progress on answering questions more quickly than in pure math, where problems can take years to solve.

    The future of crossing over

    The future of interdisciplinary research will depend a lot on the next generation, but Penn is well positioned to continue leading these efforts thanks to the proximity of the two departments, shared grants, cross-listed courses, and students and postdocs that actively work on problems across fields. “There is this constant osmosis of basic knowledge that builds up students who are literate and comfortable with sophisticated language,” says Pantev. “I think we are ahead of the curve, and I think we’ll stay ahead of the curve.”

    It’s something that many at Penn agree is a unique feature of their two departments. “It’s very rare to have such close relationships between mathematicians who really listen to what we say,” says Ovrut. “Penn should be proud of itself for having that kind of synergy. It is not something you see every day.”

    6
    Ovrut (left) was one of the co-leads, along with Donagi, of the incredibly successful joint math and physics program, the first official collaboration between the two departments at Penn.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 4:53 pm on February 7, 2020 Permalink | Reply
    Tags: , Magnetic microrobots use capillary forces to coax particles into position, , Penn Today   

    From Penn Today: “Magnetic microrobots use capillary forces to coax particles into position” 


    From Penn Today

    February 6, 2020
    Penn Today Staff

    At microscopic scales, picking, placing, collecting, and arranging objects is a persistent challenge. Advances in nanotechnology mean that there are ever more complex things we’d like to build at those sizes, but tools for moving their component parts are lacking.

    1
    Particles are strongly attracted to the corners of square-shaped robots. The green outline shows the trajectory the particle takes as the robot approaches.

    New research from the School of Engineering and Applied Science shows how simple, microscopic robots, remotely driven by magnetic fields, can use capillary forces to manipulate objects floating at an oil-water interface. This system was demonstrated in a study published in the journal Applied Physics Letters.

    The study was led by Kathleen Stebe, Richer & Elizabeth Goodwin Professor in Penn Engineering’s Department of Chemical and Biomolecular Engineering, and Tianyi Yao, a graduate student in her lab. Nicholas Chisholm, a postdoctoral researcher in Stebe’s lab, and Edward Steager, a research scientist in Penn Engineering’s GRASP lab contributed to the research.

    The microrobots in the Penn team’s study are thin slices of magnet, about a third of a millimeter in diameter. Despite having no moving parts or sensors of their own, the researchers refer to them as robots because of their ability to pick and place arbitrary objects that are even smaller than they are.

    That ability is a function of the specialized environment where these microrobots work: at the interface between two liquids. In this study, the interface is between water and hexadecane, a common oil. Once there, the robots deform the shape of that interface, essentially surrounding themselves with an invisible “force field” of capillary interactions.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 12:44 pm on February 6, 2020 Permalink | Reply
    Tags: "Looking to mud to study how particles become sticky", , Fluids mechanics, , , Penn Today   

    From Penn Today: “Looking to mud to study how particles become sticky” 


    From Penn Today

    February 5, 2020
    Katherine Unger Baillie

    A collaboration of geophysicists and fluids mechanics experts led to a fundamental new insight into how tiny ‘bridges’ help particles of all kinds form aggregates.

    1
    Using a model system of glass particles, researchers from Penn found “solid bridges” formed by smaller-size particles between larger ones. The same bridges were present in suspensions of clay, a common component of natural soils. These structures provided stability, the team found, even when a moving channel of water threatened to wash the particle clumps away. (Video: Jerolmack laboratory)

    2
    Tiny ‘bridges’ help particles stick together. Credit: CC0 Public Domain

    It happens outside every time it rains: The soil gets wet and may form sticky mud. Then it dries. Later it might rain again. Each wetting and rewetting affects the structure and stability of the soil. These changes are taken into account when, for example, architects and engineers design, site, and construct buildings. But more broadly, the science of how particles stick together and then pull apart touches fields as diverse as natural hazards, crop fertilization, cement production, and pharmaceutical design.

    Uniting these disparate fields, a team at the University of Pennsylvania has found that when particles are wet and then allowed to dry, the size of those particles has a lot to do with how strongly they stick together and whether they stay together or fall apart the next time they are wetted.

    What lends these sticky aggregates strength, the team found, are thin bridges formed when particles of the material are suspended in a liquid and then left to dry, leaving thin strands of particles that connect larger clumps. The strands, which the researchers call solid bridges, increase the aggregates’ stability 10- to 100-fold.

    The researchers reported their findings in the journal Proceedings of the National Academy of Sciences.

    “This solid bridging phenomenon may be ubiquitous and important in understanding the strength and erodibility of natural soils,” says Paulo Arratia, a fluid mechanics engineer in Penn’s School of Engineering and Applied Science and a coauthor on the study.

    “We found that a particle’s size can outweigh the contribution of its chemical properties when it comes to determining how strongly it sticks to other particles,” says Douglas Jerolmack, a geophysicist in the School of Arts and Sciences and the paper’s corresponding author.

    The research team was led by Ali Seiphoori, formerly a postdoc in Jerolmack’s lab and now at the Massachusetts Institute of Technology, and included physics postdoc Xiao-guang Ma. The current work developed from investigations they had been pursuing in conjunction with Penn’s Perelman School of Medicine on asbestos, specifically how its needle-like fibers stick to one other and to other materials to form aggregates. That got them thinking more generally about what determines the strength and stability of an aggregate.

    The group took an experimental approach to answering this question by creating a simple model of particle aggregation. They suspended glass spheres of two sizes, 3 microns and 20 microns, in a droplet of water. (For reference, a human hair is roughly 50 to 100 microns in width.) As the water evaporated, the edges of the droplet retreated, dragging the particles inward. Eventually the shrinking water droplet transformed into multiple smaller droplets connected by a thin water bridge, known as a capillary bridge, before that, too, evaporated.

    The team found that the extreme suction pressures caused by evaporation pulled the small particles so tightly together that they fused together in the capillary bridges, leaving behind solid bridges between the larger particles, to which they also bound, once the water evaporated completely.

    When the team rewet the particles, applying water in a controlled flow, they found that aggregates composed solely of the 20-micron particles were much easier to disrupt and resuspend than those composed of either the smaller particles, or mixtures of small and larger particles.

    “We found that if aggregates composed of only particles larger than 5 microns were rewet, they collapsed,” Jerolmack says. “But under 5 microns, nothing happens, the aggregates were stable.”

    In further tests with mixtures of particles of five different sizes—more closely mimicking natural soil composition—the researchers found the same bridging effect at different scales. The largest particles were bridged by the second largest, which were in turn bridged by the third largest, and so on. Even mixtures that contained only a small fraction of smaller particles became more stable thanks to solid bridging.

    How much more stable? To find out, Seiphoori painstakingly glued the probe of an atomic-force microscope to a single particle, let it set, and then quantified the “pull-off force” required to remove that particle from the aggregate. Repeating this for particles in aggregates of both big and small particles, they found that particles were 10 to 100 times harder to pull off when they had formed a solid bridge structure than in other configurations.

    To convince themselves that the same would be true with materials besides their experimental glass beads, they performed similar experiments using two types of clay that are both common components of natural soils. The principals held; the smaller clay particles and the presence of solid bridges made aggregates stable. And the reverse was also true. When clay particles smaller than 5 microns were removed from the suspensions, their resulting aggregates lost cohesion.

    “Clay soils are thought to be fundamentally cohesive,” says Jerolmack, “and that cohesiveness has usually been attributed to their charge or some other mineralogic property. But we found this very surprising thing that it doesn’t seem to be the fundamental properties of clay that make it sticky but rather the fact that clay particles tend to be very small. It’s a brand-new explanation for cohesion.”

    These new insights about the contribution of particle size to aggregate stability open up new possibilities for considering how to enhance stability of materials like soil or cement when desired. “You could envision stabilizing soils before a construction project by adding smaller particles that help bind the soil together,” Jerolmack says.

    In addition, the production of a variety of materials, from medical devices to LED screen coatings, relies on thin film deposition, which the researchers say might benefit from the controlled production of aggregates that they observed in their experiments.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 12:32 pm on January 22, 2020 Permalink | Reply
    Tags: "Kirigami designs hold thousands of times their own weight", , , Penn Today, , Using the origami-inspired art of paper cutting and folding it is possible to create super strong models from lightweight soft materials without the need for adhesives or fasteners.   

    From Penn Today: “Kirigami designs hold thousands of times their own weight” 


    From Penn Today

    January 21, 2020
    Erica K. Brockmeier

    A team of researchers found that using the origami-inspired art of paper cutting and folding, it is possible to create super strong models from lightweight soft materials without the need for adhesives or fasteners.

    2
    A close-up view of the weight-bearing kirigami structures created by Xinyu Wang while working in Randall Kamien’s lab. Each raised triangle platform is supported by neighboring flaps (shown outlined in blue) that work together to hold the structure in place without tape or adhesive.

    The Japanese art of origami (from ori, folding, and kami, paper) transforms flat sheets of paper into complex sculptures. Variations include kirigami (from kiri, to cut), a version of origami that allows materials to be cut and reconnected using tape or glue. But while both art forms are a source of ideas for science, architecture, and design, each has fundamental limitations. The flat folds required by origami result in an unlockable overall structure, while kirigami creations can’t be unfolded back into their original, flattened states because of the adhesive.

    Taking inspiration from both art forms, researchers describe a new set of motifs for creating lightweight, strong, and foldable structures using soft materials. These kirigami structures can support 14,000 times their weight and, because they don’t require adhesives or fasteners, can easily be flattened and refolded. Published in Physical Review X, the work was conducted by visiting graduate student Xinyu Wang and professor Randall Kamien of Penn in collaboration with Simon Guest from the University of Cambridge.

    Wang, a Ph.D. student at Southeast University, was interested in studying the mechanical properties of origami and kirigami structures and reached out to Kamien to start a new collaboration. After Wang arrived at the Kamien lab in September 2018, Kamien asked her to try some new designs using his group’s set of rules for exploring kirigami structures.

    3
    Wang and the Kamien lab collected the largest books they could find from across the physics department. They found that seven copies of the five-pound “Gravitation” textbook could be supported by a single kirigami sheet. (Image: Randall Kamien)

    Shortly thereafter, Wang showed Kamien a new design for a kirigami triangle that had tilted walls. Kamien was initially surprised to see that Wang had left the excess flaps from the cuts in place. “The usual kirigami route is to cut that off and tape it,” says Kamien. Wang “found that, in this particular geometry, you can get the flaps to fit.”

    While a single triangle wasn’t particularly strong on its own, the researchers noticed that when several were arranged in a repetitive design, the force they could support was much greater than expected. “Here was this structure that didn’t require tape, it had cuts, and it was really strong,” Kamien says. “Suddenly, we have this system that we hadn’t anticipated at all.”

    To figure out what made this geometry so resilient, Wang made several versions of different “soft” materials, including paper, copper, and plastic. She also made versions where the cut flaps were taped, cut, or damaged. Using industry-grade tension and compression testing equipment at the Laboratory for Research on the Structure of Matter, the scientists found that the geometric structure could support 14,000 times its own weight. The tilted, triangular design was strongest when the flaps were undamaged and untapped, and it was also stronger than the same design with vertical walls.

    With the help of Guest, the researchers realized that two deviations from the group’s typical kirigami rules were key to the structure’s strength. When the walls of the triangles are angled, any force applied to the top can be translated into horizontal compression within the center of the design. “With the vertical ones, there’s no way to turn a downward force into a sideways force without bending the paper,” says Kamien. They also found that the paper-to-paper overlap from leaving the cut flaps in place allowed the triangles to press up against their neighbors, which helped distribute the vertical load.

    5
    Experiments were conducted using industry-grade tension and compression testing equipment to see how much load the structures could bear. When the structures finally collapse, walls either buckle in or buckle out, with the latter marked by red lines. This observation helps explain why structures with taped or damaged flaps failed to support much weight: Under pressure, the triangles “splay” outward and need to have close-fitting neighbors in order to stay in place. (Image: Xinyu Wang and Randall Kamien)

    This paper is yet another example of how kirigami can be used as a “tool” for scientists and engineers, this time for creating strong, rigid objects out of soft materials. “We figured out how to use materials that can bend and stretch, and we can actually strengthen these materials,” says Wang. One possible application could be to make inexpensive, lightweight, and deployable structures, such as temporary shelter tents that are strong and durable but can also be easily assembled and disassembled.

    Kamien also pictures this Interleaved Kirigami Extension Assembly as a way to create furniture in the future. “Someday, you’ll go to IKEA, you fold the box into the furniture, and the only thing inside is the cushion. You don’t need any of those connectors or little screws,” says Kamien.

    Kamien also pictures this Interleaved Kirigami Extension Assembly as a way to create furniture in the future. “Someday, you’ll go to IKEA, you fold the box into the furniture, and the only thing inside is the cushion. You don’t need any of those connectors or little screws,” says Kamien.

    Thanks to Wang’s “inspired” design and Kamien’s burgeoning collaboration with Wang and her advisors Jianguo Cai and Jian Feng , the possibilities for future ideas and designs are endless. “There were things about this study that are totally outside the scope of what a physicist would know,” says Kamien. “It was this perfect blend of what I could do and what she could do.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 9:30 am on January 9, 2020 Permalink | Reply
    Tags: "Coral reef resilience", , , , , Katie Barott, , Penn Today,   

    From Penn Today: Women in STEM-“Coral reef resilience” Katie Barott 


    From Penn Today

    January 8, 2020
    Katherine Unger Baillie
    Eric Sucar, Photographer

    With coral reefs under threat from climate change, marine biologist Katie Barott of the School of Arts and Sciences is examining the strategies that may enable corals to bounce back from warming temperatures and acidifying oceans.

    1
    Marine biologist Katie Barott investigates the strategies certain corals may use to tolerate the warmer temperatures and acidic waters that climate change is bringing to the world’s oceans.

    Mass coral-bleaching events, which occur when high ocean temperatures cause coral to expel the algae that dwell inside them, are a relatively recent phenomenon. The first widespread bleaching event occurred in 1983, the year before Penn marine biologist Katie Barott was born.

    The next one happened about 15 years later. And the intervals between them continue to shrink. In 2014, one bleaching event in Hawaii was so extreme that it carried over to affect corals into a second summer.

    “They’re increasing in frequency, getting closer and closer,” says Barott, an assistant professor in the School of Arts and Sciences’ Department of Biology. “And the ocean temperature is getting warmer and warmer, so the severity is increasing, too.”

    Yet as dramatic as the phenomenon sounds—and appears—coral bleaching does not always equate with coral death. Algae can return to corals once ocean temperatures cool, and scientists have observed formerly white corals regain their color in subsequent seasons.

    In a multifaceted research project funded by a grant from the National Science Foundation (NSF), Barott and members of her lab are studying the mechanisms by which corals withstand the effects of climate change, which include not only the warmer temperatures that trigger bleaching but also acidification of ocean waters, a slower-moving creep with subtle yet significant consequences.

    2
    Bleached finger corals reside directly next to other corals that have withstood a bleaching event in Kaneohe Bay in Hawaii. Barrot’s research attempts to untangle some of the factors that cause some corals to be particularly hardy or resilient. (Image: Katie Barott)

    Barott’s work, based in Kaneohe Bay on Oahu, Hawaii, focuses on two of the bay’s dominant coral species: rice coral (Montipora capitata) and finger coral (Porites compressa). Barott began working there during a postdoctoral fellowship at the Hawaii Institute of Marine Biology, conducting studies on which the new work is based.

    Climate threats

    Corals are invertebrate animals that live in large colonies, together forming intricate skeletons of varied shapes. To obtain food, they rely heavily on a symbiotic relationship with algae, which establish themselves within the corals’ tissue and produce food and energy for the coral through photosynthesis. A change in temperature or pH can upset this partnership, triggering the algae’s expulsion.

    “That leaves the coral essentially starving,” Barott says.

    Since her postdoctoral days, Barott has been working with colleagues in Hawaii to monitor coral patches. After the 2014-15 bleaching event, researchers were surprised and heartened to find certain patches of corals didn’t succumb to the bleaching, even those located directly adjacent to stark white corals. And many of those that did bleach bounced back within a month or so of the onset of cooling autumn temperatures.

    At the time Barott was writing her NSF grant application, she planned to compare the differences between bleached and unbleached corals. Yet just as the grant kicked off in July, another bleaching event was unfolding in Hawaii.

    “That gave us this unexpected opportunity to go back to those same colonies to see if the ones that bleached last time were the same ones that bleached again this past fall,” she says. “And more or less we saw the same patterns: The ones that bleached last time bleached again this time and vice versa. That gives us compelling evidence that there’s something specific about these resilient individuals that is make them resist bleaching, even in very warm temperatures.”

    Mechanisms of resilience

    While high temperatures triggers bleaching, acidity plays a key role in coral vitality as well. Lower seawater pH impedes corals’ ability to build their calcium carbonite skeletons, resulting in weaker, more fragile structures.
    Barott collects finger corals to take back for further analysis. Her research projects include investigations of the algae that lives symbiotically with the coral, and the bacteria that compose the corals’ microbiome. (Image: Courtesy of Katie Barott)

    In earlier work, Barott had discovered that corals possess a pH “sensor” that can respond to changes in their environment. And, indeed, sea water acidity can vary widely in the course of a day, a season, or a year, swinging as much as 0.75 pH units in a day. Perhaps, Barott hypothesizes, coral have molecular “tools” that they use to withstand these daily fluctuations that they could also employ to contend with the gradual ocean acidification that is occurring as the concentration of CO2 in sea water rises.

    3
    Barott collects finger corals to take back for further analysis. Her research projects include investigations of the algae that lives symbiotically with the coral, and the bacteria that compose the corals’ microbiome. (Image: Courtesy of Katie Barott)

    “Maybe there are some reefs that are going to be more resistant to ocean acidification because they’re used to seeing these really large daily swings and are sort of primed to deal with that challenge,” she says.

    She’s also curious about how bleaching impacts corals’ ability to tolerate pH changes more generally. Using molecular tools, she and her students are investigating the epigenetic changes that affect how genes are “read” and translated into functional proteins in the organisms. Such changes could occur much more rapidly than coral, a long-lived species, could evolve to deal with a changing environment.

    In a variety of projects, the scientists are examining differences between species of coral, between species of the algal symbionts, and between populations located in different places in the Kaneohe lagoon.

    Early results suggest differences between the rice and finger coral in their strategies for managing bleaching.

    “One really resists the bleaching, but if it does succumb then it fares a lot worse than the one that bleaches more readily,” says Barott. “That one seems to be more susceptible to losing its symbionts, but if it does it recovers fast and has lower overall mortality.”

    Planning for the future

    Barott’s group is collaborating with others in Hawaii to see if hardier corals could be propagated to rebuild damaged reef communities.

    “We’re at the proof-of-principle stage,” she says, “where we’re trying to figure out if some of these differences are heritable.”

    4
    Tank experiments in Barott’s lab in Philadelphia complement field work done in Oahu, Hawaii.

    While some of that work is being completed in Hawaii, carefully tended tanks in the basement of the Leidy Laboratories of Biology allow Barott and her students to complete experiments in Philadelphia on corals. Using both corals shipped from the field and sea anemones, a useful stand-in for corals due to their ease of care and rapid reproduction, the lab has been tracking the impacts of temperature and pH stress on energy systems, genetics, and even the microbiome of corals, the bacteria with which the corals and algae cohabitate.

    “The surface of coral is analogous to the lining of your lungs or intestines,” Barott says. “It’s covered in cilia, it’s got a mucus layer over the top of it, and there are tons and tons of bacteria that live in that mucus layer. We think those bacteria are playing a role in the health of the coral, but we don’t know if it’s playing a role in their temperature sensitivity, so that’s something we’ll be looking at.”

    With this “whole organism” approach, Barott’s aims to inject some optimism and scientific rigor into what is a largely dire outlook for corals worldwide. Encouragingly, she notes, this year’s bleaching event in Hawaii was much less severe than predicted, and corals that had bleached in 2014 were less strongly affected by this year’s event.

    “These reefs are facing a lot of impacts, not just from climate but also from local development, sedimentation, nutrient pollution,” she says. “Our hope is to predict how corals will respond to these challenges and maybe one day use our findings to assist them in rebuilding resilient reefs.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 8:31 am on January 2, 2020 Permalink | Reply
    Tags: "The long history of David Rittenhouse Lab", , , Maths, Penn Today,   

    From Penn Today: “Space, time, and laboratories- The long history of David Rittenhouse Lab” 


    From Penn Today

    December 24, 2019

    David Brainard
    Susan Ahlborn

    Penn alums who return to campus often marvel at its transformation. Renovation projects have rejuvenated buildings like Fisher-Bennett Hall, the home of the English department and the Cinema Studies Program and one of the main teaching spaces on campus. The Perelman Center for Political Science and Economics, which opened last year, is a major hub for the social sciences. And the construction of the Carolyn Lynch Laboratory and the Stephen A. Levin Building have advanced the life sciences. Of the 26 buildings that house the people, programs and departments that make up Penn Arts & Sciences, nine are either less than 15 years old or have undergone major renovations in that time.

    1
    The original wing is a red brick structure that is adjacent to Shoemaker Green next to the Palestra. The 1967 addition is in a more modern style, and faces Walnut Street. DRL is home to the Department of Mathematics, the Department of Physics and Astronomy, the Mathematics, Physics and Astronomy Library and the Multi-Media and Educational Technology Services Center. The High Bay Lab was added in 2012. The building is named after David Rittenhouse (1731-1796), who was professor of astronomy at Penn, the first director of the United States Mint, and president of the American Philosophical Society.

    2

    One place that has remained the same in the midst of all this change is the 65-year-old David Rittenhouse Laboratory (DRL). Since 1954, the Math department, along with Physics and Astronomy, has been housed here, at the southeast corner of 33rd and Walnut Streets. Built in two phases, DRL takes up 243,002 square feet and stretches for a city block. It contains the offices and labs of 86 standing faculty, as well as grad students and post-doctoral fellows, and it provides 20 classrooms used by departments across the School.

    While the building itself might resemble a 1950s high school, the departments in it have a history of groundbreaking contributions to their fields. But a building with history is also a building that was not designed for today’s science. DRL is the legacy of an era when government partnered closely with higher education and invested heavily in facilities.

    Today, the National Science Foundation, the Department of Defense, foundations, and industry continue to fund individual research studies, and in some cases major scientific equipment. But government support for buildings themselves is now greatly reduced, and universities must find other ways to provide the modern facilities that can attract talented faculty and the graduate students that are the lifeblood of a good science department, to make possible cutting-edge research, and to facilitate excellence in teaching in the sciences.

    “Penn had really built nothing since the Depression set in,” says history of art’s David Brownlee, coauthor of “Building America’s First University: An Historical and Architectural Guide to the University of Pennsylvania.” “The DRL showed a reinvestment in West Philadelphia and an engagement with the new scientific mandates of the late 20th century. And it’s our first building that really looks like a modern building.”

    __________________________________________________________

    A Building in Two Parts
    1954 building

    James R. Edmonds, Jr., AR’12, Architect

    “Penn had really built nothing since the Depression set in,” says History of Art’s David Brownlee, coauthor of Building America’s First University: An Historical and Architectural Guide to the University of Pennsylvania. “The DRL showed a reinvestment in West Philadelphia and an engagement with the new scientific mandates of the late 20th century. And it’s our first building that really looks like a modern building.”
    1967 addition

    J. Roy Carroll, AR’26, GAR’28, Architect

    “It was in the spirit of what was being called the Philadelphia School. It’s a building for science that looks picturesque, not rational and regular and repetitive,” says Brownlee.

    3
    University Archives

    4
    David Rittenhouse

    65 Years of DRL

    1954
    The new physics and mathematics building opens. It’s named after David Rittenhouse, an inventor, astronomer, professor, and surveyor, second in awesomeness only to his friend Ben Franklin. An addition is completed in 1967.

    1957
    Physics and Astronomy gets funding from the Atomic Energy Commission to construct an accelerator with Princeton.

    USSR launches Sputnik I.

    1960
    In Physics and Astronomy, Eli Burstein helps lead the creation of Penn’s interdisciplinary Laboratory for Research on the Structure of Matter. The center has been continuously funded and is currently led by Arjun Yodh.

    1963
    Math’s Murray Gerstenhaber discovers an algebraic structure that will be named for him.

    1966
    Star Trek premieres.

    1969
    Humans land on the moon.

    5

    1972
    Physics and Astronomy’s John Robert Schrieffer shares the Nobel Prize in Physics for developing the first successful quantum theory of superconductivity.

    1973
    The first public-key cryptosystem is used for secure data transmission.

    1977
    Voyager I and II launch.

    NASA/Voyager 1

    NASA/Voyager 2

    1980
    Richard Feynman proposes quantum computing.

    Richard Feynman © Open University

    1982
    Math’s Eugenio Calabi is inducted into the National Academy of Sciences for accomplishments including the development of the Calabi conjecture, which led to Calabi-Yau manifolds.
    Physics and Astronomy’s Paul Steinhardt and his student Andreas Albrecht formulate the first viable inflationary theory of the universe.

    1985
    Math’s Peter Freyd and his student David Yetter are co-discoverers of the HOMFLY polynomial, a knot invariant in the mathematical field of knot theory.

    1988
    The Math department hosts first major U.S.-U.S.S.R. mathematics conference in modern times.

    Stephen Hawking publishes A Brief History of Time.

    Stephen Hawking

    6

    1993
    Magic: The Gathering, the first trading-card game, debuts and sells out. It’s created by Math’s Richard Garfield, C’85, GR’93, a student of Herbert Wilf.

    1994
    Math’s David Harbater coauthors a proof of Abhyankar’s conjecture, for which he shares the Cole Prize from the American Mathematical Society.

    1995
    Tom Lubensky of Physics and Astronomy coauthors Principles of Condensed Matter Physics, an influential textbook which defines the field of soft condensed matter physics.
    7

    1998
    Math’s Herbert Wilf receives the Steele Prize of the American Mathematical Society for Lifetime Achievement.

    1999
    Math’s Richard Kadison receives the Steele Prize of the American Mathematical Society for Lifetime Achievement.

    2000
    Former Professor of Physics and Astronomy Alan Heeger shares the Nobel Prize in Chemistry for work done at Penn on conductive polymers with Chemistry Professor Alan MacDiarmid and fellow Hideki Shirakawa.

    While filming A Beautiful Mind, Russell Crowe attends a Math Rademacher Lecture in DRL. No one notices.

    2002
    In Physics and Astronomy, Raymond Davis shares the Nobel Prize in Physics for detecting cosmic neutrinos.

    2004
    Physics and Astronomy’s Philip Nelson publishes his textbook Biological Physics, now a resource for biophysics curricula worldwide.

    2005
    Ron Donagi of Math coauthors a breakthrough paper on producing a Heterotic Standard Model.

    2008
    The Math department creates the Applied Mathematics and Computational Science Program.

    2009
    Following the arrival of Mark Trodden and Justin Khoury, Physics and Astronomy establishes the Center for Particle Cosmology to address questions about the universe and fundamental theories of matter and energy.

    6

    2010
    Using modern techniques, Math’s Philip Gressman and Robert Strain solve the 140-year-old Boltzmann equation.
    NASA confirms the presence of large quantities of water ice on the north pole of the Moon.

    2011
    Andrea Liu of Physics and Astronomy identifies defects that mediate flow in solids ranging from crystalline to completely disordered, enabling microscopic understanding of how solids deform and ultimately break if pushed too far.

    2012

    Voyager I enters interstellar space.

    Math’s Antonella Grassi develops a program to study elliptic fibrations with Julius Shaneson. Their findings inspire a completely new formulation of F-theory in physics.
    7
    Math’s Antonella Grassi

    2014
    In Math, Florian Pop helps to prove the full Oort Conjecture on cyclic covers, while Ted Chinburg and David Harbater advance knowledge on the non-cyclic group.

    2015
    Math’s Tony Pantev and Ron Donagi are selected to lead the Simons Collaboration for Homological Mirror Symmetry (HMS), a group exploring HMS and its applications.

    2016
    Math’s Charles Epstein receives the Bergman Prize of the American Mathematical Society for fundamental contributions including his research on a relative index on the space of embeddable Cauchy-Riemann structures.

    Physics and Astronomy’s Eugene Beier and Joshua Klein are part of the SNO collaboration that shares in a Breakthrough Prize for their work on neutrino oscillations.
    12

    SNOLAB, Sudbury, Ontario, Canada.

    2018
    Math’s Robert Ghrist begins publishing Calculus BLUE, 25 hours of free animated video lectures for multivariable calculus. He and his team, in partnership with Honeywell Intl., also develop powerful new methods arising from algebraic topology.

    13
    Math’s Robert Ghrist

    Hidden Figures hits theaters.

    Physics and Astronomy’s Mark Devlin and his group begin work on an 8,000-pound large aperture telescope receiver destined for the Simons Observatory in the Atacama Desert.

    LBL The Simons Array in the Atacama in Chile, with the 6 meter Atacama Cosmology Telescope

    2019
    Scientific American covers research led by Physics and Astronomy’s Mirjam Cvetic that finds a “quadrillion” string theory solutions.

    Physics and Astronomy’s Charles Kane and Eugene Mele receive the Breakthrough Prize for their work on topological insulators, which conduct electricity only on their surfaces.

    Six years of observation of distant galaxies for the Dark Energy Survey ends, beginning world-leading cosmological analyses by Bhuvnesh Jain, Masao Sako, Gary Bernstein, and others in Physics and Astronomy.

    Dark Energy Survey


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam at an altitude of 7200 feet

    Timeline of the Inflationary Universe WMAP

    The Dark Energy Survey (DES) is an international, collaborative effort to map hundreds of millions of galaxies, detect thousands of supernovae, and find patterns of cosmic structure that will reveal the nature of the mysterious dark energy that is accelerating the expansion of our Universe. DES began searching the Southern skies on August 31, 2013.

    According to Einstein’s theory of General Relativity, gravity should lead to a slowing of the cosmic expansion. Yet, in 1998, two teams of astronomers studying distant supernovae made the remarkable discovery that the expansion of the universe is speeding up. To explain cosmic acceleration, cosmologists are faced with two possibilities: either 70% of the universe exists in an exotic form, now called dark energy, that exhibits a gravitational force opposite to the attractive gravity of ordinary matter, or General Relativity must be replaced by a new theory of gravity on cosmic scales.

    DES is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 400 scientists from over 25 institutions in the United States, Spain, the United Kingdom, Brazil, Germany, Switzerland, and Australia are working on the project. The collaboration built and is using an extremely sensitive 570-Megapixel digital camera, DECam, mounted on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory, high in the Chilean Andes, to carry out the project.

    Over six years (2013-2019), the DES collaboration used 758 nights of observation to carry out a deep, wide-area survey to record information from 300 million galaxies that are billions of light-years from Earth. The survey imaged 5000 square degrees of the southern sky in five optical filters to obtain detailed information about each galaxy. A fraction of the survey time is used to observe smaller patches of sky roughly once a week to discover and study thousands of supernovae and other astrophysical transients.

    We see a picture of a black hole. Everyone says, “Wow.”

    The first image of a black hole. This is the supermassive black hole at the center of the galaxy Messier 87. Image via JPL/ Event Horizon Telescope Collaboration.

    EHT map

    Katie Bouman-Harvard Smithsonian Astrophysical Observatory. Headed to Caltech.

    Katie Bouman of Harvard Smithsonian Observatory for Astrophysics, headed to Caltech, with EHT hard drives from Messier 87

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 7:06 am on December 23, 2019 Permalink | Reply
    Tags: , Certain types of materials have a “memory” of how they were processed., , Penn Today,   

    From Penn Today and University of Chicago: “Researchers use a material’s ‘memory’ to encode unique physical properties” 


    From Penn Today

    and

    U Chicago bloc

    From University of Chicago

    A new study shows that, as materials age, they “remember” prior stresses and external forces, which scientists and engineers can then use to create new materials with unique properties.

    1
    Examples of disordered systems trained in this study, including (from left) a jammed packing of discs, a network based on jamming, a disordered holey sheet, and a random network based on triangular lattice. A new study shows that disordered systems like these can “remember” prior stressors, which researchers can then use to imbue the material with unique properties. (Image: Daniel Hexner, Andrea Liu, Sidney Nagel, and Nidhi Pashine)

    A new study published in Science Advances found that certain types of materials have a “memory” of how they were processed, stored, and manipulated. Researchers were then able to use this memory to control how a material ages and to encode specific properties that allow it to perform new functions. This creative approach for designing materials was the result of a collaboration between Penn’s Andrea Liu and Sidney R. Nagel, Nidhi Pashine, and Daniel Hexner from the University of Chicago.

    Liu and Nagel have worked together for many years on the physics of disordered systems. In contrast to ordered systems, which have systematic and repeating patterns, disordered systems are arranged randomly. An illustrative example is a natural wall made of tightly packed dirt, where individual grains aren’t neatly stacked but instead clump together to form a rigid structure. Researchers are interested in these systems because their randomness allows them to be easily transformed into new mechanical metamaterials with unique mechanical properties.

    2
    An example of a disordered (left) versus and ordered system.

    One important property that materials scientists would like to control is how a material responds when an external force is applied. When most materials are stretched in one direction, they shrink perpendicularly, and when compressed they expand perpendicularly, like a rubber band—when it is stretched it becomes thin, and when compressed becomes thicker.

    Materials that do the opposite, ones that shrink perpendicularly when compressed and become thicker when stretched, are known as auxetics. These materials are rare but are suspected to be better at absorbing energy and be more fracture-resistant. Researchers are interested in creating auxetic materials to help improve the function of materials that, among other things, could absorb shock.

    In this study, the researchers wanted to see if they could use a disordered material’s “memory” of the prior stresses it had encountered to transform the material into something new. First, they ran computer simulations of normal materials under pressure and selectively altered atomic bonds to see which changes could make the material auxetic. They discovered that, by cutting the bonds along the areas with the most external stress, they could digitally create an auxetic material.

    3
    A depiction of a sheet with a disordered pattern of holes. The sheet on the left is auxetic under compression along one of the major axes. With directed aging of the four holes (shown in red) while the sheet is under compression, the system gains non-auxetic properties. (Image: Daniel Hexner, Andrea Liu, Sidney Nagel, and Nidhi Pashine)

    Using this insight, the team then took a Styrofoam-like material and added “memory” by allowing the material to age under specified stresses. To make the material auxetic they applied a constant pressure to the material and let it age naturally. “With the whole thing under pressure, it adjusted itself. It turned itself from a normal material into a mechanical metamaterial,” says Liu.

    This incredibly simple and effective process is a step closer towards a materials science “holy grail” of being able to create materials with specific atomic-level structures without the need for high-resolution equipment or atomic-level modifications. The approach described in this paper instead only requires a bit of patience while the system gains “memory” and then ages naturally.

    Liu says that it is a “totally different” way to think about making new materials. “You start with a disordered system, and if you apply the right stresses you can make it come out with the properties you want,” she says.

    This work also has a strong connection to structures in biology. Organs, enzymes, and filament networks are natural examples of disordered systems that are difficult to emulate synthetically because of their complexity. Now, researchers could use this simpler approach as a starting point to create complex human-made structures that take inspiration from the wide range of properties seen in biology.

    Nagel is optimistic about the future. “In addition to making auxetic materials,” he says, “we have also used a computer to design in precise mechanical control of distant parts of the material by applying local stresses. This too is inspired by biological activity. We now need to see if this, too, can be made to work by aging a real material in the laboratory.”

    “The possibilities at this stage seem limitless,” says Nagel. “Only by further theoretical work and experimentation will we begin to understand what are the limits to this new concept of material design.”

    This research was supported by National Science Foundation grants DMR-1420709 and DMR-1404841, U.S. Department of Energy grants FG02-03ER46088 and DE-FG02-05ER46199, and Simons Foundation awards 348125, 454945, and 327939.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Chicago Campus

    An intellectual destination

    One of the world’s premier academic and research institutions, the University of Chicago has driven new ways of thinking since our 1890 founding. Today, UChicago is an intellectual destination that draws inspired scholars to our Hyde Park and international campuses, keeping UChicago at the nexus of ideas that challenge and change the world.

    The University of Chicago is an urban research university that has driven new ways of thinking since 1890. Our commitment to free and open inquiry draws inspired scholars to our global campuses, where ideas are born that challenge and change the world.

    We empower individuals to challenge conventional thinking in pursuit of original ideas. Students in the College develop critical, analytic, and writing skills in our rigorous, interdisciplinary core curriculum. Through graduate programs, students test their ideas with UChicago scholars, and become the next generation of leaders in academia, industry, nonprofits, and government.

    UChicago research has led to such breakthroughs as discovering the link between cancer and genetics, establishing revolutionary theories of economics, and developing tools to produce reliably excellent urban schooling. We generate new insights for the benefit of present and future generations with our national and affiliated laboratories: Argonne National Laboratory, Fermi National Accelerator Laboratory, and the Marine Biological Laboratory in Woods Hole, Massachusetts.

    The University of Chicago is enriched by the city we call home. In partnership with our neighbors, we invest in Chicago’s mid-South Side across such areas as health, education, economic growth, and the arts. Together with our medical center, we are the largest private employer on the South Side.

    In all we do, we are driven to dig deeper, push further, and ask bigger questions—and to leverage our knowledge to enrich all human life. Our diverse and creative students and alumni drive innovation, lead international conversations, and make masterpieces. Alumni and faculty, lecturers and postdocs go on to become Nobel laureates, CEOs, university presidents, attorneys general, literary giants, and astronauts.

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 11:08 am on December 9, 2019 Permalink | Reply
    Tags: , INFLUENCING NANOSCALE INSTRUMENTATION, Maya Lassiter, , Penn Today,   

    From Penn Today: Women in STEM- “When Curiosity Meets Nano Device Fabrication” Maya Lassiter 


    From Penn Today

    Nov 21, 2019 [Just now in social media]

    1
    Maya Lassiter

    Experiencing the democratization of media through third-party applications like LimeWire, YouTube and MySpace may have influenced the perspective and career trajectory of a woman who wants to impact the process of nanofabrication.

    “I lived through the CD-to-iPod-to-iPhone progression and felt that computers and technology could be a means by which to increase expression and understanding. That probably has a lot to do with my fascination with electrical and computer engineering,” says Maya Lassiter, doctoral GEM Fellow in the Department of Electrical and Systems Engineering at Penn Engineering.

    At Penn, Lassiter is applying an instrumentation and systems perspective to understand how nanoscale robots can be fabricated, controlled and used to further biological research. Along the way she hopes to inform the practice of creating devices from a holistic understanding of design, resource use and application.

    INFLUENCING NANOSCALE INSTRUMENTATION

    “I am interested in what nanoscale instrumentation can uncover regarding cell behavior and tissue dynamics, and how they affect larger systems,” says Lassiter. “I hope to create devices that have rhyme and reason — such as a clear rationale for materials use. As we advance the science of nanofabrication, we should introduce manufacturing processes and creative solutions that are much broader than those currently being implemented. Those changes can be changes for the better, and I want to be part of that.”

    Ultimately, she also wants her research to help further the understanding of how biological systems work in order to engineer nanoscale instrumentation that works with the systems, not against them. “I am especially interested in developing non-destructive devices for neural systems so our attempts to engage with specific cells do not come at the expense of harming the surrounding tissue.”

    TAKING A HOLISTIC FOCUS ON TECHNOLOGY

    Lassiter, who earned her BS and MS degrees in Electrical and Computer Engineering and was named the Outstanding Woman in Engineering at Carnegie Mellon University, was excited to continue her education at Penn Engineering for a number of reasons. “I get to work in the Singh Center for Nanotechnology, an exciting facility with world-class technical staff. Plus, I have the resource of Penn Engineering’s faculty who are at the frontier of science and technology,” she says. “Philadelphia is a well-connected city and a great place to be a graduate student. Coming from Pittsburgh, I am glad to experience another part of the state, where there is an active art and broader city culture that I want to get to know!”

    Lassiter is a GEM Fellow, part of the National GEM Consortium that is dedicated to enhancing the value of the nation’s human capital by increasing the participation of underrepresented groups (African Americans, American Indians, and Hispanic Americans) at the master’s and doctoral levels in engineering and science. “I believe I have something to offer in the creation of technology,” she says. “My long-term goal is to change how we think about community in engineering. I am not sure about the path to get there, but my next step will be to make work that conveys a holistic understanding of technology.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 12:15 pm on December 5, 2019 Permalink | Reply
    Tags: "These overlooked global diseases take a turn under the microscope", , , Hookworm, Leishmaniasis, , Penn Today,   

    From Penn Today: “These overlooked global diseases take a turn under the microscope” 


    From Penn Today

    December 4, 2019
    Katherine Unger Baillie, Writer
    Eric Sucar, Photographer

    1
    In rural areas of Nigeria, such as this small fishing village in the north, children are at risk of infection with hookworm as well as other parasites. De’Broski Herbert of the School of Veterinary Medicine is embarking on a study of the disease in Nigerian schoolchildren. (Image: De’Broski Herbert)

    Most people don’t die from tropical diseases like hookworm, schistosomiasis, or even malaria. But these understudied diseases, often caused by parasites, rob people of health in sometimes insidious ways.

    For example, schistosomiasis is a disease caused by a waterborne, snail-transmitted parasite, and it’s the research focus of the School of Veterinary Medicine’s Robert Greenberg.

    2
    Schistosomiasis, a disease caused by parasitic flatworms, has long been a research focus for Penn Vet’s Robert Greenberg. (Image: John Donges/Penn Vet)

    “It’s not necessarily a death sentence, though there are fatalities” says Greenberg, a research associate professor of pathobiology. “But you get anemia, children get stunted in terms of growth and cognitive abilities. It’s a disease that keeps people in poverty.”

    Such diseases, by and large, receive less financial support and, as a result, far less scientific attention than those that more often afflict residents of wealthier nations, such as diabetes and heart disease.

    Penn Vet researchers, however, have committed attention to these diseases, which, taken as a whole, affect billions around the globe. Their work benefits from the niche strengths of the school, specifically in immunology and host-pathogen interactions.

    “At the Vet School, a third of our funding supports infectious disease research,” says Phillip Scott, vice dean for research and academic resources and a professor of microbiology and immunology in the Department of Pathobiology. “That’s pretty amazing, given that the School is also awarded funding for regenerative medicine, for cancer, and for a variety of other areas.”

    That strength is seen in the research portfolios of some of the more senior faculty, such as Christopher Hunter’s work on toxoplasmosis, James “Sparky” Lok’s studies of Strongyloides, Carolina Lopez’s investigations of lung infections, and Bruce Freedman and Ron Harty’s efforts against Ebola and other hemorrhagic viral diseases. It has attracted newer faculty members, like cryptosporidium expert Boris Striepen, to Penn Vet.

    3
    Parasitology professor James Lok’s studies of the development and basic biology of parasites, particularly the roundworm
    Strongyloides, have implications for finding new drug candidates. Veterinary schools have traditionally been strongholds of parasitology research, and Penn Vet is no exception. (Image: Eric Sucar)

    Raising awareness

    Penn Vet’s De’Broski Herbert, for example, an associate professor of pathobiology, had held prior positions at Cincinnati Children’s Hospital and the University of California, San Francisco. He had felt called to work on hookworm, a parasite he first learned of growing up in the South from his great-grandmother, who warned him about walking around barefoot because of the risk of contracting the parasite. But at the medical centers where he worked, he shifted gears away from studying the parasite itself, instead focusing on related research in asthma and allergy.

    5
    As part of his hookworm research in Nigeria, Herbert (left), speaking with Babatunde Adewale of the Nigerian Institute for Medical Research, hopes to study the impacts of infection on the microbiome, the immune system, and more. (Image: Courtesy of De’Broski Herbert)

    “Here, our veterinary students are likely to encounter parasites in their patients, so working directly on the parasite is easier to justify,” Herbert says.

    This spring, Herbert traveled to Nigeria where, working with partners at the Nigerian Institute for Medical Research, he launched a study of hookworm in 300 school-aged children in five sites around the northern and central portions of the country.

    “The goal is to first establish what the prevalence of the disease really is and draw attention to that,” Herbert says. “And secondly, this is a place where the World Health Organization is going in and doing mass treatments, so I’m also interested in learning something very novel about the association between the microbiome, tissue repair, immune suppression, and metabolism in these children in Nigeria.”

    Pairing basic and translational science

    Those insights could lead to treatments, but they will also likely shed new light on the basic science of how hookworms affect their host. This pairing of basic and applied work is characteristic of Penn Vet scientists. In Scott’s lab, for instance, which has long pursued studies of the tropical disease leishmaniasis, advances in basic science have unfurled alongside insights that stand to reshape treatment of this parasitic infection which, in its cutaneous form, can cause serious and chronic skin ulcers.

    “When I was a postdoc at NIH, there’s something my boss used to say that I still use in my talks,” says Scott. “He said, ‘Leishmaniasis has done more for immunology than immunology has done for leishmaniasis.’ And you could substitute parasitology for leishmaniasis and it would be much the same quote.

    7
    The Leishmania parasite (in red), transmitted by a sandfly, can cause painful, disfiguring ulcers. Immunologist Phillip Scott and collaborators including Daniel Beiting have worked to understand the immune response to infection and better tailor treatment for those affected. (Image: Courtesy of Phillip Scott)

    “What I think is exciting right now,” he adds, “is that that’s going to change.”

    As part of this contribution toward advancements against parasitic disease, Scott has traveled regularly to a leishmaniasis clinic in Brazil to obtain samples for his research and, back at Penn, has paired up with dermatology and microbiome experts such as Elizabeth Grice in the Perelman School of Medicine, and Dan Beiting from Penn Vet’s Center for Host-Microbial Interactions to break new ground.

    No vaccine exists for leishmaniasis and current therapies fail a substantial percentage of the time. But recent publications from Scott’s lab have revealed new information about how the disease and existing treatments work and when to predict when they don’t. At the same time, Scott and colleagues’ research into the immunology of the infection has identified ways that FDA-approved drugs could be leveraged to alleviate the most severe forms of leishmaniasis.

    New diagnostics

    A major hurdle to matching appropriate therapies with neglected disease comes at one of the earliest stages of medical intervention: diagnostics. Researchers at Penn Vet are employing innovative techniques to fill these unmet needs. Robert Greenberg is one who has crossed disciplinary boundaries to do so.

    In a partnership between Greenberg and Haim Bau of Penn’s School of Engineering and Applied Science, the scientists are working to craft an improved diagnostic test for schistosomes, which can lead to schistosomiasis, causing anemia, tissue fibrosis and lesions, malnutrition, learning difficulties, and, depending on the parasite species, bladder cancer and heightened HIV risk.

    Greenberg has studied the ion channels that govern key biological functions in schistosomes to potentially develop drug targets that paralyze and kill the organisms. And by adapting insights from other researchers about additional parasitic-specific targets, he’s helping Bau train his microfluidic, portable diagnostic system on schistosomes to one day help clinicians make point-of-care diagnoses and issue timely treatment for infected patients.

    “The current diagnostics are pretty terrible,” Greenberg says. “We’re looking at some new approaches now that should give us a much earlier, more sensitive, and more specific diagnosis for individual patients that might be able to detect other coinfections simultaneously.”

    At Penn Vet’s New Bolton Center, Marie-Eve Fecteau and Ray Sweeney are also taking part in the design of a 21st-century solution to diagnostics of an insidious and challenging disease, in this case, a disease that takes a particular toll on livestock: paratuberculosis, or Johne’s disease. Caused by the bacterium Mycobacterium avium paratuberculosis, the condition affects ruminants such as cows and goats and drastically decreases their weight and milk production.

    8
    Infectious diseases take a toll on livestock as well, indirectly impacting human health and livelihoods. Large animal veterinarians Marie-Eve Fecteau and Raymond Sweeney are making progress on a stall-side diagnostic system that could quickly identify calves infected with paratuberculosis, halting the spread of infection. (Image: Louisa Shepard)

    “Ruminants are a very important part of survival and livelihood in developing countries,” says Fecteau, an associate professor of food animal medicine and surgery. “Families may rely on only one or two cows to provide for their nutritional needs or income, and if that cow is affected by Johne’s, that’s a serious problem.”

    Paratuberculosis has been shown to be endemic in parts of India and elsewhere in Asia and is also a burden for U.S. farms, where 70% of dairy herds test positive for the infection. Separating infected animals from the herd is a key step to stem the spread, but the bacteria have proved difficult to grow in the lab, making diagnosis challenging.

    Fecteau and Sweeney, the Mark Whittier & Lila Griswold Allam Professor at Penn Vet, are hoping to change that, working with Beiting and biotechnology firm Biomeme to develop a “lab in a fanny pack,” as they call it: A stall-side diagnostic test that relies on PCR to identify infected animals from stool samples within hours.

    “This is the kind of technology that could be extremely valuable for use in areas where sophisticated technology is harder to come by,” says Sweeney.

    Stopping disease where it starts

    Elsewhere at Penn Vet, researchers are approaching globally significant diseases by focusing on the vector. In the insectary that is part of Michael Povelones’s lab, he and his team test methods to stop disease-transmission cycles within mosquitoes.

    8
    The tens of thousands of mosquitoes in Michael Povelones’s insectary enable new insights into how the disease vectors defend themselves against infection. (Image: Rebecca Elias Abboud)

    In the work, which relies on disrupting the way that mosquitoes interact with or respond immunologically to the pathogens they pass on, Povelones, an assistant professor of pathobiology, has explored everything from dengue to Zika to heart worm to elephantiasis, and his discoveries have implications for targeting a much longer list of diseases. In a recent study, Povelones and colleagues developed a new model system for studying the transmission of diseases caused by kinetoplastids, a group of parasites that includes the causative agents of Chagas disease and leishmaniasis.

    “We think this could be a model for a number of important neglected diseases,” Povelones says.

    In the latest of his team’s work finding ways to activate mosquitoes’ immune system to prevent pathogen transmission, they’ve identified a strategy that both blocks heartworm and the parasite that causes elephantiasis.

    “These two diseases have very different behavior once they’re in the mosquito, so we’re still figuring out why this seems to work for both,” says Povelones. “But we’re very encouraged that it does.”

    Using these types of creative approaches is a common thread across the Vet School, and the researchers’ efforts and successes seem to be multiplying. To continue accelerating progress, the School is developing a plan to harness these strengths, working with existing entities such as the Center for Host-Microbial Interactions internally and cross-school units such as the Institute for Immunology.

    “We are a key part of the biomedical community at Penn and bring a valuable veterinary component to the table in confronting diseases of poverty,” says Scott.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 12:40 pm on November 19, 2019 Permalink | Reply
    Tags: "Researchers create better light-trapping devices", Acoustic resonators like the cavity of a drum or a half-full wine glass naturally vibrate at certain frequencies of sound waves to produce specific tones., Penn Today, , The phenomenon of resonance can also be applied to light waves with optical resonators being key components of devices such as lasers and sensors.   

    From Penn Today: “Researchers create better light-trapping devices” 


    From Penn Today

    November 15, 2019
    Erica K. Brockmeier

    A new study shows how the performance of optical resonators can be improved using topological physics, which can lead to more efficient lasers, sensors, and telecommunication devices.

    1
    An abstract depiction of the optical resonator’s nine unique topological charges. The separate charges are able to merge together, akin to how waves in the ocean can crash together and either form larger waves or cancel one another out. The wavy landscape along the bottom of the image connects to the periodic nature of the device itself. (Image: Lei Chen)

    Anyone who’s ever played the drums, tuned a guitar, or even made a wine glass “sing” by circling a finger along its edge knows about resonance. Acoustic resonators, like the cavity of a drum or a half-full wine glass, naturally vibrate at certain frequencies of sound waves to produce specific tones. The phenomenon of resonance can also be applied to light waves, with optical resonators being key components of devices such as lasers and sensors.

    A study published in Nature describes a new design for optical resonators that are more effective at trapping light, an important fundamental step towards making more efficient optical devices. The work was conducted by Bo Zhen and Ph.D. student Jicheng Jin of Penn and researchers at Peking University and MIT.

    Part of what makes light so difficult to trap in a resonator is that light is made of high-frequency waves, meaning that their wavelengths are extremely small—millions of times smaller than the acoustic waves people hear every day. In order to trap these small waves for a long time, optical resonators must be not only incredibly small but also extremely precise. “The problem is that the fabrication is not perfect,” explains Zhen. “Naturally, the fabrication process will introduce roughness onto the surface and fluctuations to the original design, so the actual device in practice is always bumpy.”

    The “bumpy” and imperfect nature of optical resonators is what currently limits a device’s quality factor, or the amount of time that the resonator can trap light before the waves fade away. Given the limitations in engineering such devices, the researchers sought to make an optical resonator that was less prone to inherent imperfections.

    This work was based on Zhen’s prior research on the theory of topological charges, also referred to as bound states in the continuum. Topological charges form by interference, a common wave phenomenon that can be seen when waves crash into one another and either add up to make larger waves or cancel each other out. Topological charges occur when the radiation waves coming out from the device cancel each other out, enabling the device to contain light’s energy for longer.

    With insights from Zhen’s theory, the researchers designed, simulated, and fabricated optical resonator devices called photonic crystal slabs, which are patterned with nanometer-sized holes spaced evenly apart from one another. Their device was still “imperfect,” with uneven surfaces visible under a scanning electron microscope, but the unique topological feature of the design greatly improved the quality factor, or the ability to trap light for a much longer period of time than otherwise possible.

    One unique feature of the device is that it could generate nine unique topological charges. Each separate charge then merges into one, causing an even stronger cancellation of the radiation waves, trapping light within the device for longer periods of time.

    The merging of the charges was a phenomenon that had been predicted in previous work, explains Zhen, but the group’s latest paper provided a strong theoretical understanding of its effect on quality factors. “The fact that they have nine charges merging at the same point is a very unique feature. At first it is quite misleading; you can interpret it in different ways, and we were sidetracked towards some other directions. Eventually, through a lot of thinking, everything worked out.”

    Their innovative platform, with a quality factor 10 times greater than other devices that don’t use merging topological charges, can lead to improvements in numerous optics-based applications. Furthermore, the researchers already demonstrated the usability of their approach on an immediate real-world application, as the study looked at wavelengths of light that are already being used for telecommunication.

    Thanks to their complementary areas of expertise, from device fabrication at Peking University and theoretical physics at Penn, the scientists were able to develop a simple, physics-based solution to a previously unsolved engineering challenge.

    “It improves the quality without optimizing fabrication,” says Jin, who recently earned his master’s degree from Peking University and is now a graduate student in Zhen’s lab. “You don’t have to do demanding work to improve the fabrication methods; you just need to choose a smart design. There are no complicated tricks, but you can see a really great improvement.”

    This research was supported by the U.S. Air Force Office of Scientific Research (Award FA9550-18-1-0133), National Science Foundation (Grant DMR-1838412), and U.S. Army Research Office (Grant W911NF-19-1-0087 and Cooperative Agreement W911NF-18-2-0048).

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
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