8,030 research outputs found

    Strings at future singularities

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    We discuss the behaviour of strings propagating in spacetimes which allow future singularities of either a sudden future or a Big-Rip type. We show that in general the invariant string size remains finite at sudden future singularities while it grows to infinity at a Big-Rip. This claim is based on the discussion of both the tensile and null strings. In conclusion, strings may survive a sudden future singularity, but not a Big-Rip where they are infinitely stretched.Comment: REVTEX 4.0, 4 pages, no figures, references adde

    All-optical hyperpolarization of electron and nuclear spins in diamond

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    Low thermal polarization of nuclear spins is a primary sensitivity limitation for nuclear magnetic resonance. Here we demonstrate optically pumped (microwave-free) nuclear spin polarization of 13C^{13}\mathrm{C} and 15N^{15}\mathrm{N} in 15N^{15}\mathrm{N}-doped diamond. 15N^{15}\mathrm{N} polarization enhancements up to 2000-2000 above thermal equilibrium are observed in the paramagnetic system Ns0\mathrm{N_s}^{0}. Nuclear spin polarization is shown to diffuse to bulk 13C^{13}\mathrm{C} with NMR enhancements of 200-200 at room temperature and 500-500 at 240 K\mathrm{240~K}, enabling a route to microwave-free high-sensitivity NMR study of biological samples in ambient conditions.Comment: 5 pages, 5 figure

    A Non-Relativistic Weyl Anomaly

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    We examine the Weyl anomaly for a four-dimensional z=3 Lifshitz scalar coupled to Horava's theory of anisotropic gravity. We find a one-loop break-down of scale-invariance at second order in the gravitational background.Comment: LaTeX, 23 pages, no figures, JHEP style; v2: typos fixed to match the published versio

    Prion protein gene sequence and chronic wasting disease susceptibility in white-tailed deer (Odocoileus virginianus)

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    The sequence of the prion protein gene (PRNP) affects susceptibility to spongiform encephalopathies, or prion diseases in many species. In white-tailed deer, both coding and non-coding single nucleotide polymorphisms have been identified in this gene that correlate to chronic wasting disease (CWD) susceptibility. Previous studies examined individual nucleotide or amino acid mutations; here we examine all nucleotide polymorphisms and their combined effects on CWD. A 626 bp region of PRNP was examined from 703 free-ranging white-tailed deer. Deer were sampled between 2002 and 2010 by hunter harvest or government culling in Illinois and Wisconsin. Fourteen variable nucleotide positions were identified (4 new and 10 previously reported). We identified 68 diplotypes comprised of 24 predicted haplotypes, with the most common diplotype occurring in 123 individuals. Diplotypes that were found exclusively among positive or negative animals were rare, each occurring in less than 1% of the deer studied. Only one haplotype (C, odds ratio 0.240) and 2 diplotypes (AC and BC, odds ratios of 0.161 and 0.108 respectively) has significant associations with CWD resistance. Each contains mutations (one synonymous nucleotide 555C/T and one nonsynonymous nucleotide 286G/A) at positions reported to be significantly associated with reduced CWD susceptibility. Results suggest that deer populations with higher frequencies of haplotype C or diplotypes AC and BC might have a reduced risk for CWD infection – while populations with lower frequencies may have higher risk for infection. Understanding the genetic basis of CWD has improved our ability to assess herd susceptibility and direct management efforts within CWD infected areas.https://digitalcommons.snc.edu/faculty_staff_works/1029/thumbnail.jp

    Fast non-negative deconvolution for spike train inference from population calcium imaging

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    Calcium imaging for observing spiking activity from large populations of neurons are quickly gaining popularity. While the raw data are fluorescence movies, the underlying spike trains are of interest. This work presents a fast non-negative deconvolution filter to infer the approximately most likely spike train for each neuron, given the fluorescence observations. This algorithm outperforms optimal linear deconvolution (Wiener filtering) on both simulated and biological data. The performance gains come from restricting the inferred spike trains to be positive (using an interior-point method), unlike the Wiener filter. The algorithm is fast enough that even when imaging over 100 neurons, inference can be performed on the set of all observed traces faster than real-time. Performing optimal spatial filtering on the images further refines the estimates. Importantly, all the parameters required to perform the inference can be estimated using only the fluorescence data, obviating the need to perform joint electrophysiological and imaging calibration experiments.Comment: 22 pages, 10 figure

    Research-to-Practice Brief: Promising Evidence that Early Head Start Can Prevent Child Maltreatment

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    This brief addresses two main questions in a sample of Early Head Start eligible children: 1) the number and type of maltreatment episodes and 2) the impact of Early Head Start on child and family involvement in the child welfare system. These findings are especially important given the lack of scalable and effective preventive interventions. In addition, they are also timely given the recent interest in fostering collaborations between early care and education programs and child welfare agencies, agencies responsible for overseeing child protection from maltreatment (OHS & ACYF, 2010; ACYF & OHS, 2011; ACYF & OCC, 2011). The current study represents a first look at the impact of Early Head Start on child maltreatment. We are continuing to collect data and will have more information in the upcoming years

    EMMS: Increasing Hope and Transforming Lives Through Improved Access to Electrical Power

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    Developing countries often face a challenge involving energy conservation. Energy Monitoring and Management Systems (EMMS) was tasked to make an energy meter in order to provide a practical way of controlling energy consumption and create a tool for teaching energy conservation. This meter should be able to measure energy usage over a period of time and prevent further energy usage after a specified amount has been consumed. In this poster, the team will explain what they have been doing in recent semesters to work towards their goal of testing and preparing this meter for implementation in Zimbabwe this summer, as well as how they have been improving the user experience through website implementation. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1005/thumbnail.jp

    Tapping Environmental History to Recreate America’s Colonial Hydrology

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    To properly remediate, improve, or predict how hydrological systems behave, it is vital to establish their histories. However, modern-style records, assembled from instrumental data and remote sensing platforms, hardly exist back more than a few decades. As centuries of data is preferable given multidecadal fluxes of both meteorology/climatology and demographics, building such a history requires resources traditionally considered only useful in the social sciences and humanities. In this Feature, Pastore et al. discuss how they have undertaken the synthesis of historical records and modern techniques to understand the hydrology of the Northeastern U.S. from Colonial times to modern day. Such approaches could aid studies in other regions that may require heavier reliance on qualitative narratives. Further, a better insight as to how historical changes unfolded could provide a “past is prologue” methodology to increase the accuracy of predictive environmental models
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