Netherlands Organization for Scientific Research

The Hague, Netherlands

Netherlands Organization for Scientific Research

The Hague, Netherlands

Time filter

Source Type

News Article | May 8, 2017
Site: www.eurekalert.org

In people with photosensitive epilepsy, flashing lights are well known for their potential to trigger seizures. The results can be quite stunning. For instance, a particular episode of Pokémon sent 685 people in Japan to the hospital. But seizures can be triggered by certain still images, too. Now, researchers reporting in Current Biology on May 8 who have conducted an extensive review of the scientific literature think they know what it is about some static pictures that can trigger seizures. The key, they propose, is a particular repetitive pattern of neural activity in the brain known as gamma oscillations that occurs when people view certain images, such as black and white bar patterns, and not others. In fact, the researchers say, it's possible that those kinds of images are responsible for other problems, such as migraine headaches, particularly in people who are generally sensitive to light. "Our findings imply that in designing buildings, it may be important to avoid the types of visual patterns that can activate this circuit and cause discomfort, migraines, or seizures," says Dora Hermes of the University Medical Center (UMC) Utrecht in the Netherlands. "Even perfectly healthy people may feel modest discomfort from the images that are most likely to trigger seizures in photosensitive epilepsy." Gamma oscillations in the brain can be measured on an electroencephalogram (EEG), a test that measures electrical activity in the brain using small electrodes attached to the scalp. Scientists have studied them since the 1980s, but there's no consensus yet on the significance of those patterns for thought, perception, or neural processing. "Some scientists argue that these oscillations are hugely important and essential for awareness, attention, and neuronal communication, while others say that they are more likely a byproduct of normal neuronal processing, like the exhaust coming out of a car--a potentially useful diagnostic signal, but not one that makes the neuronal machinery work," Hermes says. One argument against the idea that gamma oscillations are important for neural processing is that they are produced in the brain when viewing some images and not others. Grating patterns produce strong gamma oscillations while puffy clouds or many natural scenes typically do not for reasons that scientists don't fully understand. In the new report, Hermes and her colleagues, including Jonathan Winawer at New York University and Dorothée Kasteleijn-Nolst Trenité at UMC Utrecht, conclude that those gamma-oscillation-provoking images are also most likely to trigger seizures. There are simple ways to adjust an image so as to dampen that pattern of brain activity, they note. Those adjustments include reducing the contrast, adjusting the width of the bars, or shifting the image from a grate design to something more like plaid. "What we distinguish in this proposal is that the link between images that trigger photosensitive epilepsy and normal brain activity is particular to gamma oscillations, and not to other forms or neuronal responses like the overall rate of action potentials," Winawer says. The findings suggest that existing studies on gamma oscillations might offer important clues for understanding photosensitive epilepsy. Hermes and her colleagues are now designing studies to explore these patterns of brain response in patients with photosensitive epilepsy and those without. They're also working on a model to predict which natural images or scenes--a city scene, train station, or interior design, for instance--are most likely to provoke gamma oscillations and seizures. This work was supported by the Netherlands Organization for Scientific Research, the National Institutes of Health, and the EU program Marie Curie MEXCT-CT-2005-024224 "Visual Sensitivity." Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. Visit: http://www. . To receive Cell Press media alerts, contact press@cell.com.


News Article | April 27, 2017
Site: www.eurekalert.org

The synchronization of brainwaves among students during class reflects how much they like the class and each other, a team of neuroscientists has found. "How well our brainwaves sync up with those of another person appears to be a good predictor of how well we get along and how engaged we are," explains lead author Suzanne Dikker, a research scientist at New York University's Department of Psychology and Utrecht University in the Netherlands. "Overall, our findings suggest that brain-to-brain synchrony is a possible neural marker for everyday social interactions." In a departure from standard experimentation, the scientists followed a group of 12 high school students and their teacher for an entire semester and recorded their brain activity during their regular biology classes using portable electroencephalogram (EEG) technology. "The study offers a promising new method to investigate the neuroscience of group interactions," adds senior author David Poeppel, a professor in NYU's Department of Psychology and Center for Neural Science and director of the Max Planck Institute for Empirical Aesthetics in Frankfurt. Previous studies have typically measured single individuals or one-on-one interactions in highly controlled laboratory settings. By contrast, this work, appearing in the journal Current Biology, gauged dynamic social interactions in a complex group setting outside of the laboratory, shedding light on the role of brain synchrony in a more natural environment. The study also included University of Florida researchers Lu Wan, the co-lead author, and Mingzhou Ding. Using low-cost, portable brain recording equipment, the researchers compared the EEG readings of the students to each other and then explored the factors that might predict the level of synchronized brain activity between students with their self-reports on classroom engagement (e.g., students' appreciation ratings of different teaching styles and their day-to-day focus level) and measures of classroom social dynamics: Students were not only asked how much they liked each other and the teacher, but also reported on how much they liked group activities in general. Both classroom engagement and social dynamics have been shown to be critical for learning. The results showed a positive correlation between a student's ratings of the course and the student's brain synchrony with her classmates as a group--in other words, the more a student's brain waves were in sync with the those in the classroom as a whole, the more likely she was to give the course a favorable rating. Similarly, the greater the synchrony between an individual student and her classmates, the more likely they were to give positive ratings to the instructor's teaching style. The researchers also examined whether or not brain-to-brain synchrony reflected how much students like each other. To do this, students reported how personally close they were to other individuals in the class. Specifically, they found that pairs of students who felt closer to each other were more in sync during class, but only if they had interacted with each other face-to-face immediately before class. This suggests that having face-to-face interaction right before sharing an experience matters, the researchers conclude, even if you're not directly interacting during that experience (like watching a video). Finally, students who considered group activities important in their lives, exhibited higher synchrony with their classmates. The mechanism underpinning the observed brain-to-brain synchronization is likely to be shared attention, the authors posit, and this new approach provides a quantitative means to measure the factors that mediate social cohesion in groups. The research was supported by the National Science Foundation (1344285) and a Netherlands Organization for Scientific Research Award (275-89-018). A video capturing a portion of the procedure may be viewed here: https:/ (courtesy of Micah Schaffer); still images available upon request.


News Article | May 1, 2017
Site: www.futurity.org

To see if students actually enjoy a class—and get along with their classmates—check their brainwaves, a new study suggests. “How well our brainwaves sync up with those of another person appears to be a good predictor of how well we get along and how engaged we are,” explains lead author Suzanne Dikker, a research scientist at New York University’s psychology department and Utrecht University in the Netherlands. “Overall, our findings suggest that brain-to-brain synchrony is a possible neural marker for everyday social interactions.” In a departure from standard experimentation, the scientists followed a group of 12 high school students and their teacher for an entire semester and recorded their brain activity during their regular biology classes using portable electroencephalogram (EEG) technology. “The study offers a promising new method to investigate the neuroscience of group interactions,” adds senior author David Poeppel, a professor in the university’s department of psychology and Center for Neural Science, as well as director of the Max Planck Institute for Empirical Aesthetics in Frankfurt. Previous studies have typically measured single individuals or one-on-one interactions in highly controlled laboratory settings. By contrast, this work, appearing in the journal Current Biology, gauged dynamic social interactions in a complex group setting outside of the laboratory, shedding light on the role of brain synchrony in a more natural environment. “The study is groundbreaking in the sense that we studied how the brain works in the real world rather than in a well-controlled laboratory environment,” explains Mingzhou Ding, professor of biomedical engineering at the University of Florida. “The implications for social science and for education are enormous.” Using low-cost, portable brain recording equipment, the researchers compared the EEG readings of the students to each other. Then, researchers explored the factors that might predict the level of synchronized brain activity between students with their self-reports on classroom engagement (e.g., students’ appreciation ratings of different teaching styles and their day-to-day focus level) and measures of classroom social dynamics: Students were not only asked how much they liked each other and the teacher, but also reported how much they liked group activities in general. Both classroom engagement and social dynamics have been shown to be critical for learning. The results showed a positive correlation between a student’s ratings of the course and the student’s brain synchrony with her classmates as a group—in other words, the more a student’s brain waves were in sync with the those in the classroom as a whole, the more likely she was to give the course a favorable rating. Similarly, the greater the synchrony between an individual student and her classmates, the more likely they were to give positive ratings to the instructor’s teaching style. The researchers also examined whether or not brain-to-brain synchrony reflected how much students like each other. To do this, students reported how personally close they were to other individuals in the class. Specifically, they found that pairs of students who felt closer to each other were more in sync during class, but only if they had interacted with each other face-to-face immediately before class. This suggests that having face-to-face interaction right before sharing an experience matters, the researchers conclude, even if you’re not directly interacting during that experience (like watching a video). Finally, students who considered group activities important in their lives, exhibited higher synchrony with their classmates. The mechanism underpinning the observed brain-to-brain synchronization is likely to be shared attention, the authors posit, and this new approach provides a quantitative means to measure the factors that mediate social cohesion in groups. The National Science Foundation and a Netherlands Organization for Scientific Research Award supported the research.


News Article | December 6, 2016
Site: www.eurekalert.org

The tuberculosis vaccine is well known to help protect against other infectious diseases, as well as cancer, but the exact mechanisms have not been clear. A study published December 6 in Cell Reports now shows that the broad-spectrum effects of the Bacillus Calmette-Guerin (BCG) vaccine--the most widely used vaccine in the world--could be mediated by metabolic and epigenetic changes in white blood cells called monocytes through a process called trained immunity. This discovery could pave the way for strategies that combine immunological and metabolic stimulation to boost the effectiveness of vaccines and anti-cancer therapies. "The implications of these findings are double: On the one hand, we have uncovered new biological interactions that link cellular metabolism with immune responses, and on the other hand, we have opened the door for new therapeutic approaches in which metabolism modulators modulate innate immune responses and can serve as potential novel immunotherapies," says senior study author Mihai Netea of Radboud University Medical Center. "However, what it is important to realize is that this is the beginning of the process to bring this to clinical practice, and more studies are needed for that." Many epidemiological studies have demonstrated BCG's capacity to protect against infections other than tuberculosis. For example, early administration of the BCG vaccine reduces child mortality, mainly due to a reduction in lower respiratory infections and harmful immune responses triggered by infections. BCG is also used to treat bladder cancer and appears to be beneficial in several other conditions, including asthma and parasitic diseases. However, it has not been clear exactly how BCG exerts its wide-ranging effects. To address this question, Netea and his team examined BCG-induced metabolic changes in innate immune cells called monocytes. They found that vaccination induced a strong, long-lasting increase in glycolysis and, to a lesser extent, glutamine metabolism in mice and humans. This shift in glucose metabolism toward glycolysis was necessary to trigger trained immunity. This process relies on epigenetic changes, which affect gene activity without altering the DNA sequence, to enhance the ability of innate immune cells to recognize and mount more effective responses against previously encountered pathogens. Specifically, BCG-induced metabolic changes were required to induce modifications to proteins called histones, which act as scaffolds around which DNA wraps. In the human cohorts, single-nucleotide variations in genes encoding glycolysis enzymes affected the induction of trained immunity in monocytes. Taken together, the results show that cellular metabolism reprogramming is a central process involved in BCG-induced trained immunity. "These findings change the concept that the innate immune system cannot adapt in the long-term after an infection or vaccination," Netea says. "The whole concept that the function of innate immune cells can change in a stable way, for example, being improved by certain vaccines such as BCG, is a paradigm shift in immunology, as until not too long ago it was assumed that only the adaptive immune system can adapt to previous infections or vaccinations." Host immune responses are classically divided into innate immune responses, which react rapidly and nonspecifically upon encountering a pathogen, and adaptive immune responses, which are slower to develop but are specific and build up immunological memory, Netea explains. The discovery of trained immunity has challenged the dogma that only adaptive immunity can build immunological memory. According to Netea, the next step is to conduct a bigger, broader analysis of circulating monocytes in BCG-vaccinated individuals at risk for infections. "In the future, bigger studies should assess inter-individual variation in these responses, in order to be able to identify which factors influence vaccination responses at the level of a person," Netea says. "In the end, a better understanding of BCG-induced trained immunity could lead to the development of strategies that alter cellular metabolism pathways to improve human host defense mechanisms and boost the effectiveness of vaccines and immunotherapy in patients." The researchers were supported by the European Research Council; the Netherlands Organization for Scientific Research; the Northern Portugal Regional Operational Programme, under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund; and the Fundação para a Ciência e Tecnologia. Cell Reports (@CellReports), published by Cell Press, is a weekly open-access journal that publishes high-quality papers across the entire life sciences spectrum. The journal features reports, articles, and resources that provide new biological insights, are thought-provoking, and/or are examples of cutting-edge research. Visit: http://www. . To receive Cell Press media alerts, contact press@cell.com.


News Article | October 23, 2015
Site: news.mit.edu

Twelve new faculty members have been invited to join the ranks of the School of Engineering at MIT. Drawn from institutions and industry around the world, and ranging from distinguished senior researchers to promising young investigators, they will contribute to the research and educational activities of six academic departments in the school and a range of other labs and centers across the Institute. “This year we are welcoming another exceptionally strong group of new faculty to engineering,” says Ian A. Waitz, Dean of the School of Engineering. “They are remarkably accomplished, and their research spans some of the most important and pressing challenges in the world. I can’t wait to see what they do.” The new School of Engineering faculty members are: Mohammad Alizadeh will join the faculty as an assistant professor in the Department of Electrical Engineering and Computer Science in September 2015. He was a principal engineer at Cisco, which he joined through the acquisition of Insieme Networks in 2013. Alizadeh completed his undergraduate degree in electrical engineering at Sharif University of Technology and received his PhD in electrical engineering in 2013 from Stanford University, where he was advised by Balaji Prabhakar. His research interests are broadly in the areas of networked systems, data-center networking, and cloud computing. His dissertation focused on designing high-performance packet-transport mechanisms for data centers. His research has garnered significant industry interest: The Data Center TCP congestion control algorithm has been integrated into the Windows Server 2012 operating system; the QCN algorithm has been standardized as the IEEE 802.1Qau standard; and most recently, the CONGA adaptive load-balancing mechanism has been implemented in Cisco’s new flagship Application Centric Infrastructure products. Alizadeh is a recipient of a SIGCOMM best-paper award, a Stanford Electrical Engineering Departmental Fellowship, the Caroline and Fabian Pease Stanford Graduate Fellowship, and the Numerical Technologies Inc. Prize and Fellowship. Tamara Broderick will start as an assistant professor in electrical engineering and computer science in January 2015. She received a BA in mathematics from Princeton in 2007, a master of advanced study for completion of Part III of the Mathematical Tripos from the University of Cambridge in 2008, an MPhil in physics from the University of Cambridge in 2009, and an MS in computer science and a PhD in statistics from the University of California at Berkeley in 2013 and 2014, respectively. Her recent research has focused on developing and analyzing models for scalable, unsupervised learning using Bayesian nonparametrics. She has been awarded the Evelyn Fix Memorial Medal and Citation (for the PhD student on the Berkeley campus showing the greatest promise in statistical research), the Berkeley Fellowship, a National Science Foundation Graduate Research Fellowship, and a Marshall Scholarship. Michael Carbin will join the Department of Electrical Engineering and Computer Science as an assistant professor in January 2016. His research interests include the theory, design, and implementation of programming systems, including languages, program logics, static and dynamic program analyses, run-time systems, and mechanized verifiers. His recent research has focused on the design and implementation of programming systems that deliver improved performance and resilience by incorporating approximate computing and self-healing. Carbin’s research on verifying the reliability of programs that execute on unreliable hardware received a best-paper award at a leading programming languages conference (OOPSLA 2013). His undergraduate research at Stanford received the Wegbreit Prize for Best Computer Science Undergraduate Honors Thesis. As a graduate student at MIT, he received the MIT-Lemelson Presidential and Microsoft Research Graduate Fellowships. James Collins joined the faculty in the Department of Biological Engineering and as a core member of the Institute for Medical Engineering and Science. Collins received a PhD in mechanical engineering from the University of Oxford and was formerly the William F. Warren Distinguished Professor, university professor, professor of biomedical engineering, and director of the Center of Synthetic Biology at Boston University. He is a world leader in bringing together engineering principles and fundamental biology to make new discoveries and invent systems that can improve the human condition. Collins is among the founders of the field of synthetic biology. Otto X. Cordero will join the Department of Civil and Environmental Engineering as an assistant professor. He received a BS in computer and electrical engineering from the Polytechnic University of Ecuador, and an MS in artificial intelligence and PhD in theoretical biology from Utrecht University. For his dissertation, Cordero worked with Paulien Hogeweg on the scaling laws that govern the evolution of genome size in microbes. While a Netherlands Organization for Scientific Research Postdoctoral Fellow working with Martin Polz, he pursued a study of ecological and social interactions in wild populations of bacteria, and demonstrated the importance of these interactions in generating patterns of diversity and sustaining ecological function. In 2013 Cordero was awarded the European Research Council Starting Grant, the most prestigious career award in Europe, to reconstruct and model networks of ecological interactions that form between heterotrophic microbes in the ocean. Since November 2013, he has been an assistant professor at the Swiss Federal Institute of Technology in Zurich. The main goal of Cordero’s lab is to develop the study of natural microbial communities as dynamical systems, using a combination of experimental and computational approaches. Areg Danagoulian joined the faculty in the Department of Nuclear Science and Engineering (NSE) as an assistant professor in July 2014. He received a BS in physics from MIT and a PhD in experimental nuclear physics from the University of Illinois at Urbana-Champaign. He was a postdoctoral associate at the Los Alamos National Laboratory and subsequently worked as a senior scientist at Passport Systems Inc. Danagoulian’s research interests are focused in nuclear security. He works on problems in the areas of nuclear nonproliferation, technologies for arms-control treaty verification, nuclear safeguards, and nuclear-cargo security. Specific projects include the development of zero-knowledge detection concepts for weapon authentication, and research on monochromatic, tunable sources that can be applied to active interrogation of cargoes. Other areas of research include nuclear forensics and the development of new detection concepts. Danagoulian’s research and teaching will contribute to NSE’s growing program in nuclear security. Ruonan Han joined the electrical engineering and computer science faculty in September as an assistant professor. He is also a core member of the Microsystems Technology Laboratories. He earned his BS from Fudan University in 2007, an MS in electrical engineering from the University of Florida in 2009, and his PhD in electrical and computer engineering from Cornell University in 2014. Han’s research group aims to explore microelectronic-circuit and system technologies to bridge the terahertz gap between microwave and infrared domains. They focus on high-power generation, sensitive detection and energy-efficient systems. Han is the recipient of the Electrical Computing and Engineering Director’s Best Thesis Research Award and Innovation Award from Cornell, the Solid-State Circuits Society Pre-Doctoral Achievement Award and Microwave Theory Techniques Society Graduate Fellowship Award from IEEE, as well as the Best Student Paper Award from IEEE Radio-Frequency Integrated Circuits Symposium. Juejun (JJ) Hu joined the faculty in the Department of Materials Science and Engineering in January 2015 as an assistant professor and as the Merton C. Flemings Career Development Professor of Materials Science and Engineering. He comes to MIT from the University of Delaware, where he was a tenure-track assistant professor. Previously, he was a postdoc in MIT’s Microphotonics Center. As the Francis Alison Young Professor, Hu initiated and led research projects involving environmental monitoring, renewable energy, biological sensing, and optical communications. He received the 2013 Gerard J. Mangone Young Scholars Award, which recognizes promising and accomplished young faculty and is the University of Delaware’s highest faculty honor. His research is in three main areas: substrate-blind multifunctional photonic integration, mid-infrared integrated photonics, and 3-D photonic integrated circuits. Hu’s group has applied photonic technologies to address emerging application needs in environmental monitoring, renewable energy harvesting, communications, and biotechnology. He earned a BS in materials science and engineering from Tsinghua University, and a PhD from MIT. Rafael Jaramillo will join the materials science and engineering faculty as an assistant professor and the Toyota Career Development Professor in Materials Science and Engineering in the summer of 2015. He has a BS summa cum laude and an MEng, both in applied and engineering physics, from Cornell University. He also holds a PhD in physics from the University of Chicago. Jaramillo is currently a senior postdoctoral fellow at MIT in the Laboratory of Manufacturing and Productivity (LMP). His interests in renewable energy and accomplishments in developing materials systems and techniques for energy applications led to him receiving the Energy Efficiency and Renewable Energy Postdoctoral Research Fellowship from the U.S. Department of Energy. Prior to his appointment in LMP, Jaramillo was a postdoctoral fellow at the Harvard University Center for the Environment. His research interests lie at the intersection of solid-state physics, materials science, and renewable energy technologies. Stefanie Jegelka joined the faculty in the electrical engineering and computer science in January 2015. Formerly a postdoctoral researcher in the Department of Electrical Engineering and Computer Science at the University of California at Berkeley, she received a PhD in computer science from the Swiss Federal Institute of Technology in Zurich (in collaboration with the Max Planck Institute for Intelligent Systems in Tuebingen, Germany), and a diploma in bioinformatics with distinction from the University of Tuebingen in Germany. During her studies, she was also a research assistant at the Max Planck Institute for Biological Cybernetics and spent a year at the University of Texas at Austin. She conducted research visits to Georgetown University, the University of Washington, the University of Tokyo, the French Institute for Research in Computer Science and Automation, and Microsoft Research. She has been a fellow of the German National Academic Foundation and its College for Life Sciences, and has received a Google Anita Borg Fellowship, a Fellowship of the Klee Foundation, and a Best Paper Award at the International Conference on Machine Learning. Jegelka organized several workshops on discrete optimization in machine learning, and has held three tutorials on submodularity in machine learning at international conferences. Her research interests lie in algorithmic machine learning. In particular, she is interested in modeling and efficiently solving machine-learning problems that involve discrete structure. She has also worked on distributed machine learning, kernel methods, clustering, and applications in computer vision. Aleksander Madry is a former assistant professor in the Swiss Federal Institute of Technology in Lausanne (EPFL) School of Computer and Communication Sciences and started as an assistant professor in electrical engineering and computer science in February 2015. His research centers on tackling fundamental algorithmic problems that are motivated by real-world optimization. Most of his work is concerned with developing new ideas and tools for algorithmic graph theory, with a particular focus on approaching central questions in that area with a mix of combinatorial and linear-algebraic techniques. He is also interested in understanding uncertainty in the context of optimization — how to model it and cope with its presence. Madry received his PhD in computer science from MIT in 2011 and, prior to joining EPFL, spent a year as a postdoctoral researcher at Microsoft Research New England. His work was recognized with a variety of awards, including the Association for Computing Machinery Doctoral Dissertation Award Honorable Mention, the George M. Sprowls Doctoral Dissertation Award, and a number of best paper awards at Foundations of Computer Science, Symposium on Discrete Algorithms, and Symposium on Theory of Computing meetings. Xuanhe Zhao joined the Department of Mechanical Engineering faculty in September 2014 as an assistant professor. Before joining MIT, he was an assistant professor in the Department of Mechanical Engineering and Materials Science at Duke University. He earned his PhD at Harvard University in 2009. Zhao conducts research on the interfaces between solid mechanics, soft materials, and bio-inspired design. His current research goal is to understand and design new soft materials with unprecedented properties for impactful applications. His current research projects are centered on three bio-inspired themes: artificial muscle (dielectric polymers and electromechanics), tough cartilage (tough and bioactive hydrogels and biomechanics), and transformative skin (functional surface instabilities and thin-film mechanics). Zhao’s discovery of new failure mechanisms of dielectric polymers in 2011 and 2012 can potentially enhance electric energy densities of dielectric elastomers and gels by a factor of 10. In 2012, he designed a new synthetic biocompatible hydrogel with hybrid crosslinking, which achieved fracture toughness multiple times higher than articular cartilage — unprecedented by previous synthetic gels. With fiber reinforcements, Zhao further controlled the modulus of the tough hydrogel over a wide range from a few kilopascals to over 10 megapascals in 2013 and 2014. By harnessing surface instabilities such as wrinkles and creases in 2014, he dynamically varied both surface textures and colors of an electro-mechano-chemically responsive elastomers to achieve the dynamic-camouflage function of cephalopods. This work was highlighted by Nature News, reported by the The Washington Post, and featured on the MIT homepage: “How to hide like an octopus.” Xuanhe is a recipient of the National Science Foundation CAREER Award, Office of Naval Research Young Investigator Program Award, and the Early Career Researchers Award from AVS Biomaterial Interfaces Division.


van Molken T.,Radboud University Nijmegen | van Molken T.,Copenhagen University | de Caluwe H.,Radboud University Nijmegen | Hordijk C.A.,Netherlands Institute of Ecology | And 8 more authors.
Oecologia | Year: 2012

Plant pathogens and insect herbivores are prone to share hosts under natural conditions. Consequently, pathogen-induced changes in the host plant can affect herbivory, and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between viruses and non-vectoring herbivores. We investigated the effects of virus infection on subsequent infestation by a non-vectoring herbivore in a natural genotype of Trifolium repens (white clover). We tested whether infection with White clover mosaic virus (WClMV) alters (1) the effects of fungus gnat feeding on plant growth, (2) the attractiveness of white clover for adult fungus gnat females, and (3) the volatile emission of white clover plants. We observed only marginal effects of WClMV infection on the interaction between fungus gnat larvae and white clover. However, adult fungus gnat females clearly preferred non-infected over WClMV-infected plants. Non-infected and virus-infected plants could easily be discriminated based on their volatile blends, suggesting that the preference of fungus gnats for non-infected plants may be mediated by virus-induced changes in volatile emissions. The compound β-caryophyllene was exclusively detected in the headspace of virus-infected plants and may hence be particularly important for the preference of fungus gnat females. Our results demonstrate that WClMV infection can decrease the attractiveness of white clover plants for fungus gnat females. This suggests that virus infections may contribute to protecting their hosts by decreasing herbivore infestation rates. Consequently, it is conceivable that viruses play a more beneficial role in plant-herbivore interactions than generally thought. © 2012 The Author(s).


Stawski T.M.,MESA Institute for Nanotechnology | Veldhuis S.A.,MESA Institute for Nanotechnology | Castricum H.L.,University of Amsterdam | Keim E.G.,MESA Institute for Nanotechnology | And 4 more authors.
Langmuir | Year: 2011

The structural evolution of sol-gel derived lead zirconate titanate (PZT) precursor films during and after physical drying was investigated by transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), selected area electron diffraction (SAED), and time-resolved X-ray diffraction (XRD). Films were deposited from initial 0.3 mol/dm 3 precursor sols with varying hydrolysis ratios. Zr-rich grains of 1-10 nm size, embedded in a Pb-, Zr-, and Ti-containing amorphous matrix were found in as-dried films. The Zr-rich regions were crystalline at hydrolysis ratios [H 2O]/[PZT] < 27.6, and amorphous at ratios > 100. X-ray diffraction analysis of PZT and zirconia sols revealed that the crystalline nanoparticles in both sols are identical and are probably composed of nanosized zirconium oxoacetate-like clusters. This study demonstrates that time-resolved X-ray diffraction combined with electron energy loss spectroscopy mapping is a powerful tool to monitor the nanoscale structural evolution of sol-gel derived thin films. © 2011 American Chemical Society.


News Article | October 26, 2016
Site: www.eurekalert.org

A rare triple-star system surrounded by a disk with a spiral structure has been discovered by a University of Oklahoma-led research team. Recent observations from the Atacama Large Millimeter/submillimeter Array -- a revolutionary observatory in northern Chile, commonly known as ALMA -- resulted in the discovery, lending support for evidence of disk fragmentation -- a process leading to the formation of young binary and multiple star systems. Until ALMA, no one had observed a tri-star system forming in a disk like the one discovered by the OU team. John J. Tobin, professor of astrophysics in the Homer L. Dodge Department of Physics and Astronomy, OU College of Arts and Sciences, led a global team of researchers who demonstrated that the disk surrounding the tri-star system appeared susceptible to disk fragmentation. Team members represented Leiden University, The Netherlands; University of Arizona; Chalmers University of Technology, Onsala Sweden; University of Illinois; SUNY Fredonia; University of Virginia; National Radio Astronomy Observatory, New Mexico; Max-Planck, Germany; and University of California, San Diego. "What is important is that we discovered that companion stars can form in disk material surrounding a dominant star," said Tobin. "We had observed this system in the past with ALMA's predecessors, but this is the first time we have been able to clearly analyze the disk and the newborn stars within it. ALMA revealed the spiral arms and disk that led to the formation of the tri-star system. Triple systems like this one are rare, and this is the only one with a configuration like this, but we are actively searching for more." How binary stars form has been a mystery for some time, and there are different theories about how they form--one is the fragmentation of the disk around the stars that are forming. Tobin explains the formation of the disk in which the tri-star system is forming is like a figure skater doing a spin and pulls his or her arms in to gather speed. A star initially forms from a cloud of interstellar gas that is collapsing under its own gravity. The spin from the cloud causes a disk to form as the material spins faster and falls toward the star. If the disk happens to have enough material, spiral arms form and the disk can fragment to another star. "A Triple Protostar System Formed Via Fragmentation of a Gravitational Unstable Disk," will be published in Nature on October 27, 2016. Support for this research was provided by the Homer L. Dodge Department of Physics and Astrophysics Endowed Chair; the Netherlands Organization for Scientific Research, Grant No. 639.041.439; and the National Science Foundation, Grant No. AST-1410174. For more information about this research, contact OU Professor Tobin at jjtobin@ou.edu.


News Article | October 27, 2016
Site: spaceref.com

A rare triple-star system surrounded by a disk with a spiral structure has been discovered by a University of Oklahoma-led research team. Recent observations from the Atacama Large Millimeter/submillimeter Array -- a revolutionary observatory in northern Chile, commonly known as ALMA -- resulted in the discovery, lending support for evidence of disk fragmentation -- a process leading to the formation of young binary and multiple star systems. Until ALMA, no one had observed a tri-star system forming in a disk like the one discovered by the OU team. John J. Tobin, professor of astrophysics in the Homer L. Dodge Department of Physics and Astronomy, OU College of Arts and Sciences, led a global team of researchers who demonstrated that the disk surrounding the tri-star system appeared susceptible to disk fragmentation. Team members represented Leiden University, The Netherlands; University of Arizona; Chalmers University of Technology, Onsala Sweden; University of Illinois; SUNY Fredonia; University of Virginia; National Radio Astronomy Observatory, New Mexico; Max-Planck, Germany; and University of California, San Diego. "What is important is that we discovered that companion stars can form in disk material surrounding a dominant star," said Tobin. "We had observed this system in the past with ALMA's predecessors, but this is the first time we have been able to clearly analyze the disk and the newborn stars within it. ALMA revealed the spiral arms and disk that led to the formation of the tri-star system. Triple systems like this one are rare, and this is the only one with a configuration like this, but we are actively searching for more." How binary stars form has been a mystery for some time, and there are different theories about how they form--one is the fragmentation of the disk around the stars that are forming. Tobin explains the formation of the disk in which the tri-star system is forming is like a figure skater doing a spin and pulls his or her arms in to gather speed. A star initially forms from a cloud of interstellar gas that is collapsing under its own gravity. The spin from the cloud causes a disk to form as the material spins faster and falls toward the star. If the disk happens to have enough material, spiral arms form and the disk can fragment to another star. "A Triple Protostar System Formed Via Fragmentation of a Gravitational Unstable Disk," will be published in Nature on October 27, 2016. Support for this research was provided by the Homer L. Dodge Department of Physics and Astrophysics Endowed Chair; the Netherlands Organization for Scientific Research, Grant No. 639.041.439; and the National Science Foundation, Grant No. AST-1410174. For more information about this research, contact OU Professor Tobin at jjtobin@ou.edu. Please follow SpaceRef on Twitter and Like us on Facebook.


Roozemond P.C.,TU Eindhoven | Roozemond P.C.,Royal DSM | Van Drongelen M.,TU Eindhoven | Ma Z.,TU Eindhoven | And 3 more authors.
Macromolecular Rapid Communications | Year: 2015

Flow-induced structure formation is investigated with in situ wide-angle X-ray diffraction with high acquisition rate (30 Hz) using isotactic polypropylene in a piston-driven slit flow with high wall shear rates (up to ≈900 s-1). We focus on crystallization within the shear layers that form in the high shear rate regions near the walls. Remarkably, the kinetics of the crystallization process show no dependence on either flow rate or flow time; the crystallization progresses identically regardless. Stronger or longer flows only increase the thickness of the layers. A conceptual model is proposed to explain the phenomenon. Above a certain threshold, the number of shish-kebabs formed affects the rheology such that further structure formation is halted. The critical amount is reached already within 0.1 s under the current flow conditions. The change in rheology is hypothesized to be a consequence of the "hairy" nature of shish. Our results have large implications for process modelling, since they suggest that for injection molding type flows, crystallization kinetics can be considered independent of deformation history. (Figure Presented) © 2014 WILEY-VCH Verlag GmbH & Co. KGaA.

Loading Netherlands Organization for Scientific Research collaborators
Loading Netherlands Organization for Scientific Research collaborators