7,257 research outputs found

    Generalized Ohm\u27s Law In A 3-D Reconnection Experiment

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    We report the measurement of non-ideal terms of the generalized Ohm\u27s law at a reconnection site of a weakly collisional laboratory magnetohydrodynamic plasma. Results show that the Hall term dominates the measured terms; resistive and electron inertia terms are small. We suggest that electron pressure (not measured) supports the observed quasistatic reconnection rate, and that anomalous resistivity, while not ruled out, is not required to account for the results

    Three-Dimensional Structure Of Magnetic Reconnection In A Laboratory Plasma

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    The local three-dimensional structure of magnetic reconnection has been measured for the first time in a magnetohydrodynamic (MHD) laboratory plasma at the Swarthmore Spheromak Experiment. An array of 600 magnetic probes which resolve ion inertial length and MHD time scale dynamics on a single shot basis measured the magnetic structure of partial spheromak merging events. Counter-helicity spheromaks merge rapidly, and reconnection activity clearly self-generates a local component of B which breaks the standard 2D symmetry at the ion inertial scale. Consistent with prior results, no reconnection is observed for co-helicity merging

    Experimental Observation Of Energetic Ions Accelerated By Three-Dimensional Magnetic Reconnection In A Laboratory Plasma

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    Magnetic reconnection is widely believed responsible for heating the solar corona as well as for generating X-rays and energetic particles in solar flares. On astrophysical scales, reconnection in the intergalactic plasma is a prime candidate for a local source (Mpc) of cosmic rays exceeding the Greisen-Zatsepin-Kuzmin cutoff (∼10(19) eV). In a laboratory astrophysics experiment, we have made the first observation of particles accelerated by magnetic reconnection events to energies significantly above both the thermal and the characteristic magnetohydrodynamic energies. These particles are correlated temporally and spatially with the formation of three-dimensional magnetic structures in the reconnection region

    Challenges and solutions for Latin named entity recognition

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    Although spanning thousands of years and genres as diverse as liturgy, historiography, lyric and other forms of prose and poetry, the body of Latin texts is still relatively sparse compared to English. Data sparsity in Latin presents a number of challenges for traditional Named Entity Recognition techniques. Solving such challenges and enabling reliable Named Entity Recognition in Latin texts can facilitate many down-stream applications, from machine translation to digital historiography, enabling Classicists, historians, and archaeologists for instance, to track the relationships of historical persons, places, and groups on a large scale. This paper presents the first annotated corpus for evaluating Named Entity Recognition in Latin, as well as a fully supervised model that achieves over 90% F-score on a held-out test set, significantly outperforming a competitive baseline. We also present a novel active learning strategy that predicts how many and which sentences need to be annotated for named entities in order to attain a specified degree of accuracy when recognizing named entities automatically in a given text. This maximizes the productivity of annotators while simultaneously controlling quality

    Synthesis and characterization of biodegradable lignin nanoparticles with tunable surface properties

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    Lignin nanoparticles can serve as biodegradable carriers of biocidal actives with minimal environmental footprint. Here we describe the colloidal synthesis and interfacial design of nanoparticles with tunable surface properties using two different lignin precursors, Kraft (Indulin AT) lignin and Organosolv (high-purity lignin). The green synthesis process is based on flash precipitation of dissolved lignin polymer, which enabled the formation of nanoparticles in the size range of 45–250 nm. The size evolution of the two types of lignin particles is fitted on the basis of modified diffusive growth kinetics and mass balance dependencies. The surface properties of the nanoparticles are fine-tuned by coating them with a cationic polyelectrolyte, poly(diallyldimethylammonium chloride). We analyze how the colloidal stability and dispersion properties of these two types of nanoparticles vary as a function of pH and salinities. The data show that the properties of the nanoparticles are governed by the type of lignin used and the presence of polyelectrolyte surface coating. The coating allows the control of the nanoparticles’ surface charge and the extension of their stability into strongly basic regimes, facilitating their potential application at extreme pH conditions

    Prehabilitation Influences Exercise-Related Psychological Constructs Such as Self-Efficacy and Outcome Expectations to Exercise

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    Brown, K, Loprinzi, PD, Brosky, JA, and Topp, R. Prehabilitation influences exercise-related psychological constructs such as self-efficacy and outcome expectations to exercise. J Strength Cond Res 28(1): 201–209, 2014—Osteoarthritis (OA) is a clinical condition affecting more than 27 million Americans. There is no known cure for OA other than replacing the diseased joint with a joint prosthesis, a process called total knee arthroplasty (TKA). The TKA projections for the year 2016 are 1,046,000, and this number is predicted to increase by 600% to more than 3.4 million cases by 2030. The purpose of this study was to determine whether knee OA patients who engage in guided exercise (prehabilitation) before their TKA report higher levels of self-efficacy to exercise (SEE) and higher outcome expectations for exercise (OEE) than those who do not. Thirty-one participants were randomized into 2 groups (16 in prehabilitation group [PRE] and 15 in control group [CON]), all participants completed the protocol (22 women and 9 men). The PRE group participated in an exercise intervention (prehabilitation) 3 times per week for 8 weeks before TKA. One-way repeated measures analysis of variance was used to investigate the effects of group (PRE vs. CON), time (baseline T1, T2, T3, and T4), and the interaction of group and time on the dependent variables of SEE and OEE. This analysis indicated that SEE did not change over time (p = 0.62) or between the groups (p = 0.86). The analysis of the OEE indicated a significant time effect (p = 0.008). Post hoc analysis indicated that the CON group significantly declined between T2 and T4. The PRE group did not significantly change their OEE over the 4 data collection points of the study
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