1,158 research outputs found

    The Dynamics of Public Attention: Agenda‐Setting Theory Meets Big Data

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    Researchers have used surveys and experiments to better understand communication dynamics, but confront consistent distortion from self‐report data. But now both digital exposure and resulting expressive behaviors (such as tweets) are potentially accessible for direct analysis with important ramifications for the formulation of communication theory. We utilize “big data” to explore attention and framing in the traditional and social media for 29 political issues during 2012. We find agenda setting for these issues is not a one‐way pattern from traditional media to a mass audience, but rather a complex and dynamic interaction. Although the attentional dynamics of traditional and social media are correlated, evidence suggests that the rhythms of attention in each respond to a significant degree to different drummers .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106877/1/jcom12088.pd

    Rag GTPases are cardioprotective by regulating lysosomal function.

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    The Rag family proteins are Ras-like small GTPases that have a critical role in amino-acid-stimulated mTORC1 activation by recruiting mTORC1 to lysosome. Despite progress in the mechanistic understanding of Rag GTPases in mTORC1 activation, little is known about the physiological function of Rag GTPases in vivo. Here we show that loss of RagA and RagB (RagA/B) in cardiomyocytes results in hypertrophic cardiomyopathy and phenocopies lysosomal storage diseases, although mTORC1 activity is not substantially impaired in vivo. We demonstrate that despite upregulation of lysosomal protein expression by constitutive activation of the transcription factor EB (TFEB) in RagA/B knockout mouse embryonic fibroblasts, lysosomal acidification is compromised owing to decreased v-ATPase level in the lysosome fraction. Our study uncovers RagA/B GTPases as key regulators of lysosomal function and cardiac protection

    Using Faculty Learning Communities to Link FYE and High-Risk Core Courses: A Pilot Study

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    Can success rates in a gateway course be improved by linking it to a college success course? This article describes the results of a pilot study that linked a first-year biology course that had a high drop-out and failure rate to a college success course that included study skills. The proposal to link courses came from the work of a faculty learning community aimed at sharing strategies for increasing engagement in first year courses. Faculty involved in the link worked closely together. The college success course used biology content to provide hands-on study skills applications for students. The results illustrate that students in the pilot program did significantly better in the biology course as well as in their overall fall GPA than students in the same biology course who were not in the learning community

    Targeted Activation of Hippocampal Place Cells Drives Memory-Guided Spatial Behavior

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    The hippocampus is crucial for spatial navigation and episodic memory formation. Hippocampal place cells exhibit spatially selective activity within an environment and have been proposed to form the neural basis of a cognitive map of space that supports these mnemonic functions. However, the direct influence of place cell activity on spatial navigation behavior has not yet been demonstrated. Using an ‘all-optical’ combination of simultaneous two-photon calcium imaging and two-photon optogenetics, we identified and selectively activated place cells that encoded behaviorally relevant locations in a virtual reality environment. Targeted stimulation of a small number of place cells was sufficient to bias the behavior of animals during a spatial memory task, providing causal evidence that hippocampal place cells actively support spatial navigation and memory

    Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rhombus tilings

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    The degree of randomness, or partial order, present in two-dimensional supramolecular arrays of isophthalate tetracarboxylic acids is shown to vary due to subtle chemical changes such as the choice of solvent or small differences in molecular dimensions. This variation may be quantified using an order parameter and reveals a novel phase behaviour including random tiling with varying critical properties as well as ordered phases dominated by either parallel or non-parallel alignment of neighbouring molecules, consistent with long-standing theoretical studies. The balance between order and randomness is driven by small differences in the intermolecular interaction energies, which we show, using numerical simulations, can be related to the measured order parameter. Significant variations occur even when the energy difference is much less than the thermal energy highlighting the delicate balance between entropic and energetic effects in complex self-assembly processes

    Magnetism, FeS colloids, and Origins of Life

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    A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via physicalphysical interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed Krishnaswami Alladi, Springer 201

    Duality and scaling in 3-dimensional scalar electrodynamics

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    Three-dimensional scalar electrodynamics, with a local U(1) gauge symmetry, is believed to be dual to a scalar theory with a global U(1) symmetry, near the phase transition point. The conjectured duality leads to definite predictions for the scaling exponents of the gauge theory transition in the type II region, and allows thus to be scrutinized empirically. We review these predictions, and carry out numerical lattice Monte Carlo measurements to test them: a number of exponents, characterising the two phases as well as the transition point, are found to agree with expectations, supporting the conjecture. We explain why some others, like the exponent characterising the photon correlation length, appear to disagree with expectations, unless very large system sizes and the extreme vicinity of the transition point are considered. Finally, we remark that in the type I region the duality implies an interesting quantitative relationship between a magnetic flux tube and a 2-dimensional non-topological soliton.Comment: 27 pages. v2: reference and minor clarifications added, to appear in Nucl.Phys.
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