10,522 research outputs found

    Effects of the pyrethroid insecticide gamma-cyhalothrin on aquatic invertebrates in laboratory and outdoor microcosm tests

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    The sensitivity of a range of freshwater lentic invertebrates to gamma-cyhalothrin (GCH), a single enantiomer of the synthetic pyrethroid lambda-cyhalothrin, was assessed in single species laboratory tests and an outdoor multi-species ecosystem test. The most sensitive species in the laboratory single species tests with GCH was Chaoborus obscuripes (96 h EC50: 3.8 ng/l). The species sensitivity distribution curve, based on the laboratory 96 h EC50 acute toxicity data for eight species, gave a median HC5 value for GCH of 2.12 ng/l. The NOECcommunity derived from the multi-species ecosystem test was 5 ng/l, and the insects Chaoborus sp. and Caenis sp. were identified as the most sensitive species. The results indicate that the median HC5, based on eight species selected to include those known to be sensitive to pyrethroids, provided a good estimation of the NOECcommunity for GCH. Furthermore, the results for GCH indicated that the endpoints typically used in higher-tier risk assessments for pesticides in Europe (HC5 and NOECcommunity) were consistent with expectations when compared to the equivalent endpoints for the racemate LC

    The Relationship between Self-Regulation and Stress, Sleep, and Behavioral Health

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    The goal of this research was to investigate multiple aspects of self-regulation and their relationship to stress, sleep, and behavioral health. Participants (N=89, 55 females, 29 males, and 5 did not list their sex) were recruited from a high-risk Midwest high school. Participants reported their own self-regulatory ability, sleep, stress, and behavioral problems. Nail samples were also collected from a subset of the participants to assay for cortisol and DHEA. Several measures of self-regulation were found to correlate with sleep quality, behavioral problems, and perceived stress. The natural log of the ratio of cortisol to DHEA was positively correlated with multiple measures of self-regulation. These findings demonstrate a relationship a positive relationship among self-regulation, sleep quality, and improved behavioral functioning as indexed by lower levels of externalizing and internalizing behaviors. Better self-regulation also correlated with lower perceived stress, but higher physiological biomarkers of stress. These findings are discussed in the context of theoretical proposals of self-regulation and stress adaption

    Since I Fell in Love With You

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    Transport in Transitory, Three-Dimensional, Liouville Flows

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    We derive an action-flux formula to compute the volumes of lobes quantifying transport between past- and future-invariant Lagrangian coherent structures of n-dimensional, transitory, globally Liouville flows. A transitory system is one that is nonautonomous only on a compact time interval. This method requires relatively little Lagrangian information about the codimension-one surfaces bounding the lobes, relying only on the generalized actions of loops on the lobe boundaries. These are easily computed since the vector fields are autonomous before and after the time-dependent transition. Two examples in three-dimensions are studied: a transitory ABC flow and a model of a microdroplet moving through a microfluidic channel mixer. In both cases the action-flux computations of transport are compared to those obtained using Monte Carlo methods.Comment: 30 pages, 16 figures, 1 table, submitted to SIAM J. Appl. Dyn. Sy

    American skullcap (Scutellaria lateriflora): an ancient remedy for today’s anxiety?

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    Anxiety is a common but potentially serious disorder as it can lead to somatic and social dysfunction. Orthodox anxiolytics are associated with unpleasant side-effects and dependency. American skullcap (Scutellaria lateriflora) is a popular herb in traditional medicine systems and the western materia medica for anxiety and related disorders. Preliminary clinical and in vitro research provides encouraging support for its potential as a safe, well-tolerated and effective alternative

    Terrorism and political attitudes: Evidence from European social surveys

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    Terror attacks in Europe have increased substantially since the turn of the last century. Using data from European Social Surveys (ESS), we examine their effects on political attitudes and orientation by comparing within-country survey responses shortly before and after terror attacks involving at least one fatality. At the national level, we find little support for the hypothesis that terror attacks influenced attitudes towards immigration or political orientation. By contrast, there is evidence of post-attack increases in satisfaction with the national government and trust in parliament among ESS respondents living in the region that was attacked.Support came from the Comunidad de Madrid, grant EPUC3M11 (V PRICIT) and grant H2019/HUM-5891

    Nutritional status of a nereidid polychaete cultured in sand filters of mariculture wastewater

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    This study examined the nutritional composition of the intertidal marine polychaete Perinereis helleri (Nereididae)when artificially cultured in sand filters treating mariculture wastewater. Moisture levels in harvested P. helleri ranged from 758 to 855 g kg1, and ash, from 23 to 61 g kg1 wet matter (WM). Stocking density and graded size after harvest significantly affected their composition. Higher total lipid contents were found in large (>0.6 g) P. helleri(16–19 g kg1 WM) and those grown at the lowest density(1000 m2: 18 g kg 1 WM) than in small (≤0.6 g) ones (14 g kg1 WM) and those grown at the highest densities (4000–6000 m2: 13–16 g kg1 WM). Several fatty acids within a very broad profile (some 30 identified) reflected this pattern, yet their ARA/EPA/DHA ratios were relatively unaffected. Feeding the polychaete-assisted sand filters (PASF) with fish meal to increase worm biomass productivity significantly increased their DHA content. Other components (e.g. protein, phospholipids, cholesterol, carbohydrate, amino acids, nitrogen, minerals and bromophenols) and nutritional factors (e.g. maturity, feeding seaweed and endemic shrimp viral content) were also investigated. Results suggest that PASF-produced P. helleri have a well-balanced nutritional profile for penaeid shrimp and fish broodstock

    On the exactness of the Semi-Classical Approximation for Non-Relativistic One Dimensional Propagators

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    For one dimensional non-relativistic quantum mechanical problems, we investigate the conditions for all the position dependence of the propagator to be in its phase, that is, the semi-classical approximation to be exact. For velocity independent potentials we find that: (i) the potential must be quadratic in space, but can have arbitrary time dependence. (ii) the phase may be made proportional to the classical action, and the magnitude (``fluctuation factor'') can also be found from the classical solution. (iii) for the driven harmonic oscillator the fluctuation factor is independent of the driving term.Comment: 7 pages, latex, no figures, published in journal of physics