947 research outputs found

    Synaptic transmission at visualized sympathetic boutons: stochastic interaction between acetylcholine and its receptors

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    Excitatory postsynaptic currents (EPSCs) were recorded with loose patch electrodes placed over visualized boutons on the surface of rat pelvic ganglion cells. At 34 degrees C the time to peak of the EPSC was about 0.7 ms, and a single exponential described the declining phase with a time constant of about 4.0 ms; these times were not correlated with changes in the amplitude of the EPSC. The amplitude-frequency histogram of the EPSC at individual boutons was well described by a single Gaussian-distribution that possessed a variance similar to that of the electrical noise. Nonstationary fluctuation analysis of the EPSCs at a bouton indicated that about 120 ACh receptor channels were available beneath boutons for interaction with a quantum of ACh. The characteristics of these EPSCs were compared with the results of Monte Carlo simulations of the quantal release of 9000 acetylcholine (ACh) molecules onto receptor patches of density 1400 microns-2 and 0.41 micron diameter, using a kinetic scheme of interaction between ACh and the receptors similar to that observed at the neuromuscular junction. The simulated EPSC generated in this way had temporal characteristics similar to those of the experimental EPSC when either the diffusion of the ACh is slowed or allowance is made for a finite period of transmitter release from the bouton. The amplitude of the simulated EPSC then exhibited stochastic fluctuations similar to those of the experimental EPSC

    Religion, altruism, and helping strangers: a multilevel analysis of 126 countries

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    This article tests how religion relates to helping strangers, an important but rarely studied measure of social solidarity and informal social capital. It uses the Gallup World Poll, a survey with nationally representative samples of 179,961 respondents from 126 countries. It finds that religious people, members of minority religions, and people in religiously diverse countries were more likely to help a stranger. Individuals living in devout countries were more likely to help strangers even if they themselves were not religious. The results suggest that religion plays a particularly important role in promoting the prosocial norms and values that motivate helping strangers

    Humans adapt to social diversity over time

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    Humans have evolved cognitive processes favoring homogeneity, stability, and structure. These processes are, however, incompatible with a socially diverse world, raising wide academic and political concern about the future of modern societies. With data comprising 22 y of religious diversity worldwide, we show across multiple surveys that humans are inclined to react negatively to threats to homogeneity (i.e., changes in diversity are associated with lower self-reported quality of life, explained by a decrease in trust in others) in the short term. However, these negative outcomes are compensated in the long term by the beneficial influence of intergroup contact, which alleviates initial negative influences. This research advances knowledge that can foster peaceful coexistence in a new era defined by globalization and a socially diverse future

    Phylogeny of the Subfamilies of Ichneumonidae (Hymenoptera)

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    A combined morphological and molecular phylogenetic analysis was performed to evaluate the subfamily relationships of the parasitoid wasp family Ichneumonidae (Hymenoptera). Data were obtained by coding 135 morphological and 6 biological characters for 131 exemplar species of ichneumonids and 3 species of Braconidae (the latter as outgroups). The species of ichneumonids represent all of the 42 currently recognized subfamilies. In addition, molecular sequence data (cytochrome oxidase I “DNA barcoding” region, the D2 region of 28S rDNA and part of the F2 copy of elongation factor 1-alpha) were obtained from specimens of the same species that were coded for morphology (1309 base pairs total). The data were analyzed using parsimony and Bayesian analyses. The parsimony analysis using all data recovered previ-ously recognized informal subfamily groupings (Pimpliformes, Ophioniformes, Ichneumoniformes), al-though the relationships of these three groups to each other differed from previous studies and some of the subfamily relationships within these groupings had not previously been suggested. Specifically, Ophioni-formes was the sister group to (Ichneumoniformes + Pimplformes), and Labeninae was placed near Ich-neumoniformes, not as sister group to all Ichneumonidae except Xoridinae. The parsimony analysis using only morphological characters was poorly resolved and did not recover any of the three informal subfamily groupings and very few of the relationships were similar to the total-evidence parsimony analysis. The mo-lecular-only parsimony analysis and both Bayesian analyses (total-evidence and molecular-only) recovered Pimpliformes, a restricted Ichneumoniformes grouping and many of the subfamily groupings recovered in the total-evidence parsimony analysis. A comparison and discussion of the results obtained by each phylo-genetic method and different data sets is provided. It is concluded that the molecular characters produced results that were relatively consistent with traditional, non-phylogenetic concepts of relationships between the ichneumonid subfamilies, whereas the morphological characters did not (at least not by themselves). The inclusion of both molecular and morphological characters using parsimony produced a topology that was the closest to the traditional subfamily relationships. The method of analysis did not greatly affect the overall topology for the molecular-only analyses, but there were differences between Bayesian and parsi-mony results for the total-evidence analyses (especially near the root of the tree). The Bayesian results did not seem to be altered very much by the inclusion of morphological characters, unlike in the parsimony analysis. In summary, the following groups were supported in multiple analyses regardless of the characters used or method of tree-building: Pimpliformes, higher Ophioniformes, higher Pimpliformes, (Claseinae + Pedunculinae), (Banchinae + Stilbopinae), Campopleginae, Cremastinae, Diplazontinae, Ichneumoninae (including Alomya), Labeninae, Ophioninae, Poemeniinae, Rhyssinae, and Tersilochinae sensu stricto. Conversely, Ctenopelmatinae and Tryphoninae were never recovered without inclusion of other taxa. Based on the hypothesis of relationships obtained by the total-evidence parsimony analysis, the following formal taxonomic changes are proposed: Alomyinae Förster (= Alomya Panzer and Megalomya Uchida) is once again synonymized with Ichneumoninae and is now considered a tribe (Alomyini rev. stat.); and Notostilbops Townes is transferred from Stilbopinae to Banchinae, tribe Atrophini

    Interacting Three Fluid System and Thermodynamics of the Universe Bounded by the Event Horizon

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    The work deals with the thermodynamics of the universe bounded by the event horizon. The matter in the universe has three constituents namely dark energy, dark matter and radiation in nature and interaction between then is assumed. The variation of entropy of the surface of the horizon is obtained from unified first law while matter entropy variation is calculated from the Gibbss' law. Finally, validity of the generalized second law of thermodynamics is examined and conclusions are written point wise.Comment: 7 page

    Does ethnic diversity affect well-being and allostatic load among people across neighbourhoods in England?

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    Modern societies are facing unprecedented changes in their ethnic composition. Increasing ethnic diversity poses critical new challenges as people interact with new cultures, norms, and values, or avoid such encounters. Heated academic and political debates focus on whether and how changes in ethnic composition affect societies and local communities. Yet, there is insufficient scientific evidence of how living in a more diverse society affects individuals' well-being and health. The aim of this study is to test the extent to which increasing neighbourhood ethnic diversity affects individuals’ subjective health and well-being and objective stress levels as measured by allostatic load. We analyse a large panel data set containing over 47,000 English respondents living in 15,545 neighbourhoods in England from the British Household Panel Survey and the UK Household Longitudinal Study, from 2004 to 2011. We match respondents to neighbourhoods and merge contextual information about levels of neighbourhood ethnic diversity and deprivation from UK Censuses, whilst controlling for background characteristics. We distinguish between short- and long-term effects of ethnic diversity on individual subjective well-being and health as well as allostatic load using a set of multilevel mixed-effects models. We make cautious causal interpretations by estimating fixed-effects models and cross-lagged panel models. We assess the robustness of our findings by replicating our analysis using alternative composite measures of diversity and allostatic load. In the short-term, increasing ethnic diversity of local areas is associated with a dip in subjective well-being, but short-term changes are not prolonged or profound enough to affect chronic stress (allostatic load). The initial negative impact of ethnic diversity on subjective well-being and health dissipates with time. In the long-term, no effects of ethnic diversity on well-being and health or chronic stress (allostatic load) are detected. Understanding the dynamic nature of the effects of ethnic diversity on individuals has critical implications for social and public health policies – issues prominent in, for example, the UK (Brexit) and the US (election of President Donald Trump). Our analysis identifies and enables the promotion of beneficial effects, while targeting the pernicious components to turn diversity into a valuable asset in a globalising world

    Dark energy from conformal symmetry breaking

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    The breakdown of conformal symmetry in a conformally invariant scalar-tensor gravitational model is revisited in the cosmological context. Although the old scenario of conformal symmetry breaking in cosmology containing scalar field has already been used in many earlier works, it seems that no special attention has been paid for the investigation on the possible connection between the breakdown of conformal symmetry and the existence of dark energy. In this paper, it is shown that the old scenario of conformal symmetry breaking in cosmology, if properly interpreted, not only has a potential ability to describe the origin of dark energy as a symmetry breaking effect, but also may resolve the coincidence problem.Comment: 11 pages, minor revision, published online in EPJ

    Te covered Si(001): a variable surface reconstruction

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    At a given temperature, clean and adatom covered silicon surfaces usually exhibit well-defined reconstruction patterns. Our finite temperature ab-initio molecular dynamics calculations show that the tellurium covered Si(001) surface is an exception. Soft longitudinal modes of surface phonons due to the strongly anharmonic potential of the bridged tellurium atoms prevent the reconstruction structure from attaining any permanent, two dimensional periodic geometry. This explains why experiments attempting to find a definite model for the reconstruction have reached conflicting conclusions.Comment: 4 pages, 3 gif figure
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