105,802 research outputs found

    Coordination Matters : Interpersonal Synchrony Influences Collaborative Problem-Solving

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    The authors thank Martha von Werthern and Caitlin Taylor for their assistance with data collection, Cathy Macpherson for her assistance with the preparation of the manuscript, and Mike Richardson, Alex Paxton, and Rick Dale for providing MATLAB code to assist with data analysis. The research was funded by the British Academy (SG131613).Peer reviewedPublisher PD

    Kinship, lineage identity, and an evolutionary perspective on the structure of cooperative big game hunting groups in Indonesia.

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    Work was conducted among traditional, subsistence whale hunters in Lamalera, Indonesia in order to test if kinship or lineage membership is more important for explaining the organization of cooperative hunting parties ranging in size from 8-14 men. Crew identifications were collected for all 853 hunts that occurred between May 3 and August 5, 1999. Lineage identity and genetic relatedness were determined for a sample of 189 hunters. Results of matrix regression show that kinship explains little of the hunters' affiliations independent of lineage identity. Crews are much more related amongst themselves than expected by chance. This is due, however, to the correlation between lineage membership and kinship. Lineage members are much more likely to affiliate in crews, but beyond r = 0.5 kin are just as likely not to affiliate. The results are discussed vis-à-vis the evolution of cooperation and group identity

    Evaluation of behavior in transgenic mouse models to understand human congenital pain conditions

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    BACKGROUND: Containing a brain for signal processing and decision making, and a peripheral component for sensation and response, the nervous system provides higher organisms a powerful method of interacting with their environment. The specific neurons involved in pain sensation are known as nociceptors and are the source of normal nociceptive pain signaling to prompt appropriate responses. Though acute hypersensitization can be advantageous by encouraging an organism to allow an injured area to heal, chronic pain conditions can be pathological and can markedly reduce quality of life. While a variety of genes have been associated with congenital pain conditions, two rare cases examined in this study have not had their mutated genes identified. Potassium voltage-gated channel subfamily H member 8, or KCNH8, is involved in regulating action potential production and propagation, and has not been linked with pain processing of any kind to date. Here, a male patient evaluated at Boston Children’s Hospital contains a novel single-base KCNH8 mutation and possesses an extremely low sensitivity to cold temperatures and mechanical pain, but a higher sensitivity to warmer temperatures. A separate protein, intersectin-2, or ITSN2, normally functions in clathrin-mediated endocytosis and exocytosis. A second patient at Boston Children’s Hospital expresses a previously-unseen point mutation in ITSN2 and experiences erythromelalgia, characterized by episodes of intense pain and red, swollen limbs during ambient warm temperatures. Through the use of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 genome editing, this study will produce these specific genetic mutations in mouse lines to explore their effects on mammalian behavior. OBJECTIVES: This project employs two transgenic mouse models to study the behavioral phenotypes associated with rare potentially damaging mutations in KCNH8 and ITSN2 exhibited in the human patients. Through these experiments, a greater understanding of neural pain signaling and sensitivity changes can occur. METHODS: The differences in temperature preference of KCNH8 and ITSN2 mutant mice compared to wild type mice lacking these mutations was studied using thermal plates under cold and warm conditions. Direct application of acetone and von Frey filaments to mouse paws was used to study cold and mechanical sensitivity. Further testing of stamina, anxiety, coordination, and strength were also evaluated. RESULTS: A marked decrease in sensitivity to von Frey stimulation (p<0.01) and acetone administration (p<0.05) was observed in KCNH8 mutant mice. Thermal preference testing demonstrated a decreased preference for warmer temperatures as compared to wild type mice. In addition, anxiety levels were also observed to be slightly higher in these mutant KCNH8 mice (p<0.05). The mutant ITSN2 mice spent less time at cooler temperatures, though surprisingly they significantly preferred warmer conditions as compared to their wild type littermates. A full and partial reversal of these temperature preferences was demonstrated in cold and heat thermal conditions respectively after intraperitoneal gabapentin injection, which normalized the mice toward wild type behavior. CONCLUSIONS: Data from the KCNH8 mutant mouse model indicates an aversion to warmer temperatures and a decreased ability to detect cold or mechanical pressure, much like the human patient. The mutant ITSN2 mice were less likely to spend time at cooler temperatures, indicating heightened sensory sensitivity, but their preference for warmer temperatures suggests a possible desensitization of the affected nociceptors. These results often mirror the patient’s phenotype, but the preference for ambient warmer environments appears opposite to the patient. As the ITSN2 mice feel discomfort at cooler temperatures, a proposed desensitization at warmer temperatures would result in a more comfortable environment and could explain the observed preference. The trends toward normal neural firing rates achieved through gabapentin injection suggest that the aberrant responses in mutant ITSN2 mice is due to altered sensitization, but additional examination under these conditions with a larger group of mice is necessary to further unravel these signaling pathways. However, these extremely encouraging data introduce two new molecular targets for acute pain control

    A probabilistic justification for using tf.idf term weighting in information retrieval

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    This paper presents a new probabilistic model of information retrieval. The most important modeling assumption made is that documents and queries are defined by an ordered sequence of single terms. This assumption is not made in well known existing models of information retrieval, but is essential in the field of statistical natural language processing. Advances already made in statistical natural language processing will be used in this paper to formulate a probabilistic justification for using tf.idf term weighting. The paper shows that the new probabilistic interpretation of tf.idf term weighting might lead to better understanding of statistical ranking mechanisms, for example by explaining how they relate to coordination level ranking. A pilot experiment on the TREC collection shows that the linguistically motivated weighting algorithm outperforms the popular BM25 weighting algorithm

    The Individual and Collective Effects of Exact Exchange and Dispersion Interactions on the Ab Initio Structure of Liquid Water

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    In this work, we report the results of a series of density functional theory (DFT) based ab initio molecular dynamics (AIMD) simulations of ambient liquid water using a hierarchy of exchange-correlation (XC) functionals to investigate the individual and collective effects of exact exchange (Exx), via the PBE0 hybrid functional, non-local vdW/dispersion interactions, via a fully self-consistent density-dependent dispersion correction, and approximate nuclear quantum effects (aNQE), via a 30 K increase in the simulation temperature, on the microscopic structure of liquid water. Based on these AIMD simulations, we found that the collective inclusion of Exx, vdW, and aNQE as resulting from a large-scale AIMD simulation of (H2_2O)128_{128} at the PBE0+vdW level of theory, significantly softens the structure of ambient liquid water and yields an oxygen-oxygen structure factor, SOO(Q)S_{\rm OO}(Q), and corresponding oxygen-oxygen radial distribution function, gOO(r)g_{\rm OO}(r), that are now in quantitative agreement with the best available experimental data. This level of agreement between simulation and experiment as demonstrated herein originates from an increase in the relative population of water molecules in the interstitial region between the first and second coordination shells, a collective reorganization in the liquid phase which is facilitated by a weakening of the hydrogen bond strength by the use of the PBE0 hybrid XC functional, coupled with a relative stabilization of the resultant disordered liquid water configurations by the inclusion of non-local vdW/dispersion interactions
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