794 research outputs found

    How are coastal benthos fed?

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    Water movement can influence the distribution of benthos, in part, by increasing food delivery; however, the impact of advective transport and turbulent diffusion on organic matter flux to nearshore benthic communities is not well quantified. In this study, we measured the vertical particulate organic carbon (POC) and particulate phosphorus (PP) flux in nearshore Lake Michigan using two naturally occurring daughter/parent radionuclide pairs (234Th/238U and 90Y/90Sr) and compared these fluxes to coincident benthic chamber estimates of respiration and total phosphorus efflux by quagga mussels on the lakebed. We found that advective onshore transport and vertical convective mixing increased POC and PP flux to the nearshore benthos by a factor of ~15 and ~30 over offshore trap-derived estimates of flux. From these results, we hypothesize that high benthos population densities are related to an edge effect created when the dominant mechanism of particle delivery transitions from gravitational settling to convection

    Ice dynamics and mass balance in the grounding zone of outlet glaciers in the Transantarctic Mountains

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    The Antarctic grounding zone has a disproportionately large effect on glacier dynamics and ice sheet stability relative to its size but remains poorly characterised across much of the continent. Accurate ice velocity and thickness information is needed in the grounding zone to determine glacier outflow and establish to what extent changing ocean and atmospheric conditions are affecting the mass balance of individual glacier catchments. This thesis describes new satellite remote sensing techniques for measuring ice velocity and ice thickness, validated using ground measurements collected on the Beardmore, Skelton and Darwin Glaciers and applied to other Transantarctic Mountain outlet glaciers to determine ice discharge. Outlet glaciers in the Transantarctic Mountains provide an important link between the East and West Antarctic Ice Sheets but remain inadequately studied. While long-term velocities in this region are shown here to be stable, instantaneous velocities are sensitive to stresses induced by ocean tides, with fluctuations of up to 50% of the mean observed in GPS measurements. The potential error induced in averaged satellite velocity measurements due to these effects is shown to be resolvable above background noise in the grounding zone but to decrease rapidly upstream. Using a new inverse finite-element modelling approach based on regularization of the elastic-plate bending equations, tidal flexure information from differential InSAR is used to calculate ice stiffness and infer thickness in the grounding zone. This technique is shown to be successful at reproducing the thickness distribution for the Beardmore Glacier, eliminating current issues in the calculation of thickness from freeboard close to the grounding line where ice is not in hydrostatic equilibrium. Modelled thickness agrees to within 10% of ground penetrating radar measurements. Calibrated freeboard measurements and tide-free velocities in the grounding zones of glaciers in the western Ross Sea are used to calculate grounding zone basal melt rates, with values between 1.4 and 11.8 m/a⁻¹ in this region. While strongly dependent on grounding line ice thickness and velocity, melt rates show no latitudinal trend between glaciers, although detailed error analysis highlights the need for much improved estimates of firn density distribution in regions of variable accumulation such as the Transantarctic Mountains

    Speaking of That: Terms to Avoid or Reconsider in the Eating Disorders Field

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    Inspired by an article on 50 terms that, in the interest of clarity in scientific reasoning and communication in psychology, psychiatry, and allied fields, “should be avoided or at most be used sparingly and only with explicit caveats,”1 we propose a list of terms to avoid or think twice about before using when writing for the International Journal of Eating Disorders (IJED). Drawing upon our experience as reviewers or editors for the IJED, we generated an abridged list of such terms. For each term, we explain why it made our list and what alternatives we recommend. We hope that our list will contribute to improved clarity in scientific thinking about eating disorders, and that it will stimulate discussion of terms that may need to be reconsidered in our field's vocabulary to ensure the use of language that is respectful and sensitive to individuals who experience an eating disorder

    Testing the Tripartite Influence Model Among Heterosexual, Bisexual, and Lesbian Women

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    This cross-sectional study explored similarities and differences between heterosexual, bisexual, and lesbian women in levels of, and relationships between, the following constructs using a Tripartite Influence Model framework: family, peer, and media appearance pressures, thin- and muscular-ideal internalization, and eating disorder (ED) pathology. Self-identified heterosexual (n = 1,528), bisexual (n = 89), and lesbian (n = 278) undergraduate women completed the Sociocultural Attitudes Towards Appearance Questionnaire-4 and the Eating Disorder Examination-Questionnaire. Sexual orientation differences in appearance pressures, appearance-ideal internalization, and ED pathology were examined via analysis of variance tests. Relationships between these variables were examined with multi-group path analyses, controlling for age, race/ethnicity, and body mass index. Compared with lesbian women, heterosexual and bisexual women reported higher levels of peer appearance pressures. Paths from peer appearance pressures and thin-ideal internalization to shape/weight overvaluation and body dissatisfaction were strongest for bisexual women. Overall, results indicate notable similarities between heterosexual, bisexual, and lesbian women. However, preliminary evidence for potential differences highlights the importance of examining variation in ED risk between sexual minority subgroups

    Does the Tripartite Influence Model of Body Image and Eating Pathology Function Similarly Across Racial/Ethnic Groups of White, Black, Latina, and Asian Women?

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    The tripartite influence model suggests that appearance pressures from family, peers, and the media contribute to thin-ideal internalization, which leads to increased body dissatisfaction and subsequent eating disorder pathology. The tripartite influence model was initially developed and tested among primarily White samples, and emerging research suggests racial/ethnic differences in mean levels of particular model constructs. Consequently, the model\u27s appropriateness for understanding eating disorder risk in racial/ethnic minorities warrants investigation to determine its usefulness in explicating eating disorder risk in diverse populations. Participants in the current study were White (n = 1167), Black (n = 212), Latina (n = 203), and Asian (n = 176) women from five geographically disparate college campuses in the United States. Participants completed the Sociocultural Attitudes Towards Appearance Questionnaire-4, the Multidimensional Body-Self Relations Questionnaire - Appearance Evaluation Subscale, and the Eating Disorder Examination-Questionnaire. Analysis of variance was used to compare mean levels of each construct across racial/ethnic groups. Multigroup structural equation modeling was used to assess the appropriateness of the tripartite influence model for each racial/ethnic group, and to examine differences in the strength of the model pathways across groups. There were significant mean level differences across groups for most model constructs. However, results indicated similar model fit across racial/ethnic groups, with few differences in the strength of model pathways. Findings suggest that although some groups report lower levels of proposed risk factors, the sociocultural risk processes for eating pathology identified through the tripartite influence model are similar across racial/ethnic groups of young adult women. Such information can be used to inform culturally-sensitive interventions

    Evidence for the role of EPHX2 gene variants in anorexia nervosa.

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    Anorexia nervosa (AN) and related eating disorders are complex, multifactorial neuropsychiatric conditions with likely rare and common genetic and environmental determinants. To identify genetic variants associated with AN, we pursued a series of sequencing and genotyping studies focusing on the coding regions and upstream sequence of 152 candidate genes in a total of 1205 AN cases and 1948 controls. We identified individual variant associations in the Estrogen Receptor-ß (ESR2) gene, as well as a set of rare and common variants in the Epoxide Hydrolase 2 (EPHX2) gene, in an initial sequencing study of 261 early-onset severe AN cases and 73 controls (P=0.0004). The association of EPHX2 variants was further delineated in: (1) a pooling-based replication study involving an additional 500 AN patients and 500 controls (replication set P=0.00000016); (2) single-locus studies in a cohort of 386 previously genotyped broadly defined AN cases and 295 female population controls from the Bogalusa Heart Study (BHS) and a cohort of 58 individuals with self-reported eating disturbances and 851 controls (combined smallest single locus P<0.01). As EPHX2 is known to influence cholesterol metabolism, and AN is often associated with elevated cholesterol levels, we also investigated the association of EPHX2 variants and longitudinal body mass index (BMI) and cholesterol in BHS female and male subjects (N=229) and found evidence for a modifying effect of a subset of variants on the relationship between cholesterol and BMI (P<0.01). These findings suggest a novel association of gene variants within EPHX2 to susceptibility to AN and provide a foundation for future study of this important yet poorly understood condition

    Towards a data publishing framework for primary biodiversity data: challenges and potentials for the biodiversity informatics community

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    Background: Currently primary scientific data, especially that dealing with biodiversity, is neither easily discoverable nor accessible. Amongst several impediments, one is a lack of professional recognition of scientific data publishing efforts. A possible solution is establishment of a ‘Data Publishing Framework’ which would encourage and recognise investments and efforts by institutions and individuals towards management, and publishing of primary scientific data potentially on a par with recognitions received for scholarly publications. Discussion: This paper reviews the state-of-the-art of primary biodiversity data publishing, and conceptualises a ‘Data Publishing Framework’ that would help incentivise efforts and investments by institutions and individuals in facilitating free and open access to biodiversity data. It further postulates the institutionalisation of a ‘Data Usage Index (DUI)’, that would attribute due recognition to multiple players in the data collection/creation, management and publishing cycle. Conclusion: We believe that institutionalisation of such a ‘Data Publishing Framework’ that offers socio-cultural, legal, technical, economic and policy environment conducive for data publishing will facilitate expedited discovery and mobilisation of an exponential increase in quantity of ‘fit-for-use’ primary biodiversity data, much of which is currently invisible

    Source levels of social sounds in migrating humpback whales (Megaptera novaeangliae)

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    The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmission loss were estimated rather than measured. This paper presents measurements of source levels of social sounds (surface-generated and vocal sounds) of humpback whales from a sample of 998 sounds recorded from 49 migrating humpback whale groups. Sources were localized using a wide baseline five hydrophone array and transmission loss was measured for the site. Social vocalization source levels were found to range from 123 to 183 dB re 1 mu Pa @ 1 m with a median of 158 dB re 1 mu Pa @ 1 m. Source levels of surface-generated social sounds ("breaches" and "slaps") were narrower in range (133 to 171 dB re 1 mu Pa @ 1 m) but slightly higher in level (median of 162 dB re 1 mu Pa @ 1 m) compared to vocalizations. The data suggest that group composition has an effect on group vocalization source levels in that singletons and mother-calf-singing escort groups tend to vocalize at higher levels compared to other group compositions. VC 2013 Acoustical Society of America
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