2,456 research outputs found

    Ecological succession of a Jurassic shallow-water ichthyosaur fall.

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    After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early 'mobile-scavenger' and 'enrichment-opportunist' stages were not succeeded by a 'sulphophilic stage' characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed 'reef stage' with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities

    Determinants of participation in a web-based health risk assessment and consequences for health promotion programs

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    Background: The health risk assessment (HRA) is a type of health promotion program frequently offered at the workplace. Insight into the underlying determinants of participation is needed to evaluate and implement these interventions. Objective: To analyze whether individual characteristics including demographics, health behavior, self-rated health, and work-related factors are associated with participation and nonparticipation in a Web-based HRA. Methods: Determinants of participation and nonparticipation were investigated in a cross-sectional study among individuals employed at five Dutch organizations. Multivariate logistic regression was performed to identify determinants of participation and nonparticipation in the HRA after controlling for organization and all other variables. Results: Of the 8431 employees who were invited, 31.9% (2686/8431) enrolled in the HRA. The online questionnaire was completed by 27.2% (1564/5745) of the nonparticipants. Determinants of participation were some periods of stress at home or work in the preceding year (OR 1.62, 95% CI 1.08-2.42), a decreasing number of weekdays on which at least 30 minutes were spent on moderate to vigorous physical activity (ORdayPA0.84, 95% CI 0.79-0.90), and increasing alcohol consumption. Determinants of nonparticipation were less-than-positive self-rated health (poor/very poor vs very good, OR 0.25, 95% CI 0.08-0.81) and tobacco use (at least weekly vs none, OR 0.65, 95% CI 0.46-0.90). Conclusions: This study showed that with regard to isolated health behaviors (insufficient physical activity, excess alcohol consumption, and stress), those who could benefit most from the HRA were more likely to participate. However, tobacco users and those who rate

    Sometimes You Cannot Have It All: Party Switching and Affiliation Motivations as Substitutes

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    Existing research on when legislators switch parties reports inconsistent results about motivations for switching (e.g., office, ideology, and votes). I treat the motivations for party switching as substitutes and argue that many of the inconsistencies that persist can be explained by modelling the interactive effects between these motivations. For example, scholars differ in terms of whether they find that electoral considerations are an important determinant of party switching. The conflicting findings on the independent effects of electoral considerations are explained here by demonstrating that these effects are conditional on the level of office benefits a legislators enjoys, as well as the ideological distance between the legislator and party. More generally, the empirical analysis provides strong support for the substitution effect hypothesis. Thus, modelling interactive effects increases our understanding of party switching

    Search for the standard model Higgs boson at LEP

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    Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector

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    The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV

    Observation of associated near-side and away-side long-range correlations in √sNN=5.02  TeV proton-lead collisions with the ATLAS detector

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    Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

    Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach

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    Background: In this study, we quantified age-related changes in the time-course of face processing by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our approach does not rely on peak measurements and can provide a more sensitive measure of processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded discrimination task between two faces. The phase spectrum of these faces was manipulated parametrically to create pictures that ranged between pure noise (0% phase information) and the undistorted signal (100% phase information), with five intermediate steps. Results: Behavioural 75% correct thresholds were on average lower, and maximum accuracy was higher, in younger than older observers. ERPs from each subject were entered into a single-trial general linear regression model to identify variations in neural activity statistically associated with changes in image structure. The earliest age-related ERP differences occurred in the time window of the N170. Older observers had a significantly stronger N170 in response to noise, but this age difference decreased with increasing phase information. Overall, manipulating image phase information had a greater effect on ERPs from younger observers, which was quantified using a hierarchical modelling approach. Importantly, visual activity was modulated by the same stimulus parameters in younger and older subjects. The fit of the model, indexed by R2, was computed at multiple post-stimulus time points. The time-course of the R2 function showed a significantly slower processing in older observers starting around 120 ms after stimulus onset. This age-related delay increased over time to reach a maximum around 190 ms, at which latency younger observers had around 50 ms time lead over older observers. Conclusion: Using a component-free ERP analysis that provides a precise timing of the visual system sensitivity to image structure, the current study demonstrates that older observers accumulate face information more slowly than younger subjects. Additionally, the N170 appears to be less face-sensitive in older observers

    How and Why Parents Guide the Media Use of Young Children

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    Abstract Children use electronic screens at ever younger ages, but there is still little empirical research on howand why parents mediate this media use. In line with Vygotsky’s zone of proximal development, we explored whether children’s media skills and media activities, next to parents’ attitudes about media for children, and several child and parent-family characteristics, predicted parental mediation practices. Furthermore, we investigated children’s use and ownership of electronic screens in the bedroomin relationship to the child’s media skills. Data from an online survey among 896 Dutch parents with young children (0–7 years) showed that children’s use and ownership of TV, game consoles, computers and touchscreens, primarily depended on their media skills and age, not on parent’s attitudes about media for children. Only touchscreens were used more often by children, when parents perceived media as helpful in providing moments of rest for the child. In line with former studies, parents consistently applied co-use, supervision, active mediation, restrictive mediation, and monitoring, depending on positive and negative attitudes about media. The child’s media skills andmedia activities, however, had stronger relationshipswith parental mediation styles, whereas age was not related. Canonical discriminant analysis, finally, captured how the five mediation strategies varied among infants, toddlers, preschoolers, and early childhood children, predominantly as a result of children’s media skills, and media activities, i.e., playing educational games and passive entertainment use
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