814 research outputs found

    Supersymmetric reduced models with a symmetry based on Filippov algebra

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    Generalizations of the reduced model of super Yang-Mills theory obtained by replacing the Lie algebra structure to Filippov nn-algebra structures are studied. Conditions for the reduced model actions to be supersymmetric are examined. These models are related with what we call \{cal N}_{min}=2 super pp-brane actions.Comment: v3: In the previous versions we overlooked that Eq.(3.9) holds more generally, and missed some supersymmetric actions. Those are now included and modifications including a slight change in the title were made accordingly. 1+18 page

    Superdiffusive and Subdiffusive Exceptional Times in the Dynamical Discrete Web

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    The dynamical discrete web is a system of one-dimensional coalescing random walks that evolves in an extra dynamical time parameter. At any deterministic dynamical time, the paths behave as coalescing simple symmetric random walks. This paper studies the existence of (random) exceptional dynamical times at which the paths violate certain almost sure properties of random walks. It was shown in 2009 by Fontes, Newman, Ravishankar and Schertzer that there exist exceptional times at which the path starting from the origin violates the law of the iterated logarithm. Their results gave exceptional times at which the path is slightly subdiffusive in one direction. This paper extends this to obtain times at which the path is slightly superdiffusive in one direction and times at which the path is slightly subdiffusive in both directions. We also obtain upper and lower bounds for the Hausdorff dimensions of the sets of two-sided subdiffusive exceptional times, and a lower bound for the Hausdorff dimension of set of superdiffusive exceptional times.Comment: Accepted for publication in Stoch. Proc. Appli

    Academic influencers: Teaching faculty as potential departmental change agents for inclusive pedagogy

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    There is a disproportionate loss of minoritized undergraduate students from STEM majors. Faculty change efforts to confront this diversity, equity, and inclusion (DEI) challenge, such as the adoption of evidenced-based instructional approaches, has been slow. Research on affecting change in STEM departments suggests that initiatives are more successful when they are sustained and target departments rather than individuals. One potential change strategy to promote DEI-related change within a department is to embed tenure-track education-focused faculty within STEM departments. The specialist faculty have been demonstrated to pedagogically innovate within their department and consistently interact with their colleagues regarding teaching. Therefore, we sought to assess whether tenure-track education-focused faculty can influence their colleagues on instructional topics, including those related to DEI. We surveyed five STEM departments at large research-intensive campuses. The surveys had faculty select colleagues who were influential upon various aspects of instruction, including methodology, course materials, and aspects of DEI. We constructed social networks of influence across these aspects of instruction. Our analyses reveal heterogeneity across these networks. Some, like the teaching strategies network, are highly connected and involve the majority of the department, while others, like the DEI influence network, comprise a significantly smaller population of faculty. We find that tenure-track education-focused faculty are influential across all aspects of instruction and are disproportionately so in the sparsely populated DEI influence networks. This suggests that embedding these specialist faculty within departments may lead to effective sustained change efforts in the DEI values held by STEM academic departments. This research was approved by the institutional review board at the University of California, Irvine

    Metabolic Profiling of the Protozoan Parasite Entamoeba invadens Revealed Activation of Unpredicted Pathway during Encystation

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    Encystation, which is cellular differentiation from the motile, proliferative, labile trophozoite form to the dormant, resistant cyst form, is a crucial process found in parasitic and free-living protozoa such as Entamoeba, Giardia, Acanthamoeba, and Balamuthia. Since encystation is an essential process to deal with the adverse external environmental changes during the life cycle, and often integral to the transmission of the diseases, biochemical understanding of the process potentially provides useful measures against the infections caused by this group of protozoa. In this study, we investigated metabolic and transcriptomic changes that occur during encystation in Entamoeba invadens, the reptilian sibling of mammal-infecting E. histolytica, using capillary electrophoresis-tandem mass spectrometry-based metabolite profiling and DNA microarray-based expression profiling. As the encystation progressed, the levels of majority of metabolites involved in glycolysis and nucleotides drastically decreased, indicating energy generation is ceased. Furthermore, the flux of glycolysis was redirected toward chitin wall biosynthesis. We found remarkable temporal increases in biogenic amines such as isoamylamine, isobutylamine, and cadaverine, during the early period of encystation, when the trophozoites form large multicellular aggregates (precyst). We also found remarkable induction of γ-aminobutyric acid (GABA) during encystation. This study has unveiled for the first time the dynamics of the transcriptional and metabolic regulatory networks during encystation, and should help in better understanding of the process in pathogenic eukaryotes, and further development of measures controlling infections they cause

    A DECADE-BASELINE STUDY OF THE PLASMA STATES OF EJECTA KNOTS IN CASSIOPEIA A

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    We present the analysis of 21 bright X-ray knots in the Cassiopeia A supernova remnant from observations spanning 10 yr. We performed a comprehensive set of measurements to reveal the kinematic and thermal state of the plasma in each knot, using a combined analysis of two high energy resolution High Energy Transmission Grating (HETG) and four medium energy resolution Advanced CCD Imaging Spectrometer (ACIS) sets of spectra. The ACIS electron temperature estimates agree with the HETG-derived values for approximately half of the knots studied, yielding one of the first comparisons between high resolution temperature estimates and ACIS-derived temperatures. We did not observe the expected spectral evolution—predicted from the ionization age and density estimates for each knot—in all but three of the knots studied. The incompatibility of these measurements with our assumptions has led us to propose a dissociated ejecta model, with the metals unmixed inside the knots, which could place strong constraints on supernova mixing models.United States. National Aeronautics and Space Administration (Award NNX10AE25G)National Science Foundation (U.S.) (Partnerships in Astronomy & Astrophysics Research and Education Grant AST-0849736)United States. National Aeronautics and Space Administration (Earth and Space Science Fellowship)United States. National Aeronautics and Space Administration (Harriet Jenkins Predoctoral Fellowship Program)Vanderbilt University (Provost Graduate Fellowship

    The Impact of Heavy Nuclei on the Cosmogenic Neutrino Flux

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    As ultra-high energy cosmic ray protons propagate through the universe, they undergo photo-meson interactions with the cosmic microwave background, generating the `cosmogenic' neutrino flux. If a substantial fraction of the cosmic ray primaries are heavy nuclei rather than protons, however, they would preferentially lose energy through photo-disintegration, so the corresponding neutrino flux may be substantially depleted. We investigate this issue using a Monte Carlo simulation of cosmic ray propagation through interagalactic radiation fields and assess the impact of the altered neutrino fluxes on next generation neutrino telescopes.Comment: 10 pages, 3 figures; results revised to account for numerical error in propagation Monte Carlo, no significant change in conclusion

    Spinless photon dark matter from two universal extra dimensions

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    We explore the properties of dark matter in theories with two universal extra dimensions, where the lightest Kaluza-Klein state is a spin-0 neutral particle, representing a six-dimensional photon polarized along the extra dimensions. Annihilation of this 'spinless photon' proceeds predominantly through Higgs boson exchange, and is largely independent of other Kaluza-Klein particles. The measured relic abundance sets an upper limit on the spinless photon mass of 500 GeV, which decreases to almost 200 GeV if the Higgs boson is light. The phenomenology of this dark matter candidate is strikingly different from Kaluza-Klein dark matter in theories with one universal extra dimension. Elastic scattering of the spinless photon with quarks is helicity suppressed, making its direct detection challenging, although possible at upcoming experiments. The prospects for indirect detection with gamma rays and antimatter are similar to those of neutralinos. The rates predicted at neutrino telescopes are below the sensitivity of next-generation experiments.Comment: 22 pages. Figure 7 corrected, leading to improved prospects for direct detection. Some clarifying remarks include

    Willingness-to-Pay-Associated Right Prefrontal Activation During a Single, Real Use of Cosmetics as Revealed by Functional Near-Infrared Spectroscopy

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    Use of applied neuroscience to complement traditional methods of consumer research is increasing. Previously, fMRI has shown that prefrontal activity contains information relating to willingness-to-pay (WTP). The aim of the present study was to determine if functional near infrared spectroscopy (fNIRS) can record WTP-related brain activation in the dorsolateral prefrontal cortex (DLPFC) during a single, real use of cosmetic products. Thirty female participants, were divided into two groups (one low frequency users of foundation and one high frequency users of foundation), asked to apply different foundations to their face and then record how much money they were willing to pay. The oxyhemoglobin time series was analyzed with the GLM and the correlation between the beta scores for the foundations and their respective WTP values conducted for each participant. These subject level correlations were then converted to z scores and averaged for each group. The results revealed a significant mean correlation for the high but not low frequency group. In other words, the brain activity in right hemisphere dorsolateral PFC (RH-DLPFC) during single, real use of foundations correlated with their respective WTP values for the high frequency but not low frequency group. The difference between groups may reflect the importance of learning and automation on activity in RH-DLPFC. Our research provides further evidence supporting the use of fNIRS to complement traditional consumer research in a commercial setting and to extend neuroscience research into more naturalistic environments
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