281 research outputs found

    On the origin: environmental biology of fishes

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    Dynamical Drivers of the Local Wind Regime in a Himalayan Valley

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    Understanding the local valley wind regimes in the Hindu-Kush Karakoram Himalaya is vital for future predictions of the glacio-hydro-meteorological system. Here the Weather Research and Forecasting model is employed at a resolution of 1 km to investigate the forces driving the local valleywind regime in a river basin in the Nepalese Himalaya, during July 2013 and January 2014. Comparing withobservations shows that the model represents the diurnal cycle of the winds well, with strong daytime up-valley winds and weak nighttime winds in both months. A momentum budget analysis of the model output shows that in the summer run the physical drivers of the near-surface valley wind also have a clear diurnal cycle, and are dominated by the pressure gradient, advection, and turbulent vertical mixing,as well as a nonphysical numerical diffusion term. By contrast, the drivers in the winter run have a less consistent diurnal cycle. In both months, the pressure gradient, advection, numerical diffusion, and Coriolis terms dominate up to 5,000 m above the ground. The drivers are extremely variable over the valley, and also influenced by the presence of glaciers. When glaciers are removed from the model in the summer run, the wind continues further up the valley, indicating how the local valley winds might respond to future glacier shrinkage. The spatial variability of the drivers over both months is consistent with the complex topography in the basin, which must therefore be well represented in weather and regional climate models to generate accurate output

    Meteorological impacts of a novel debris-covered glacier category in a regional climate model across a Himalayan catchment

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    Many of the glaciers in the Nepalese Himalaya are partially covered in a layerof loose rock known as debris cover. In the Dudh Koshi River Basin, Nepal,approximately 25% of glaciers are debris-covered. Debris-covered glaciers havebeen shown to have a substantial impact on near-surface meteorological vari-ables and the surface energy balance, in comparison to clean-ice glaciers. TheWeather Research and Forecasting (WRF) model is often used for high-resolution weather and climate modelling, however representation of debris-covered glaciers is not included in the standard land cover and soil categories.Here we include a simple representation of thick debris-covered glaciers in theWRF model, and investigate the impact on the near-surface atmosphere overthe Dudh Koshi River Basin for July 2013. Inclusion of this new category isfound to improve the model representation of near-surface temperature andrelative humidity, in comparison with a simulation using the default categoryof clean-ice glaciers, when compared to observations. The addition of the newdebris-cover category in the model warms the near-surface air over the debris-covered portion of the glacier, and the wind continues further up the valley,compared to the simulation using clean-ice. This has consequent effects onwater vapour and column-integrated total water path, over both the portions ofthe glacier with and without debris cover. Correctly simulating meteorologicalvariables such as these is vital for accurate precipitation forecasts overglacierized regions, and therefore estimating future glacier melt and river run-off in the Himalaya. These results highlight the need for debris cover to be included in high-resolution regional climate models over debris-covered glaciers.NER

    The hypoxia that developed in a microtidal estuary following an extreme storm produced dramatic changes in the benthos

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    Runoff from an extreme storm on 22 March 2010 led, during the next 3 months, to the formation of a pronounced halocline and underlying hypoxia in the upper reaches of the microtidal Swan–Canning Estuary. Benthic macroinvertebrates were sampled between January 2010 and October 2011 at five sites along 10 km of this region. By mid-April, the number of species, total density, Simpson’s evenness index and taxonomic distinctness had declined markedly, crustaceans had disappeared and the densities of annelids and molluscs had declined slightly. These faunal attributes (except Simpson’s index) and species composition did not recover until after the end of the hypoxia. The survival of annelids and loss of crustaceans in this period reflects different sensitivities of these taxa to severe environmental stress. The results emphasise that microtidal estuaries with long residence times are highly vulnerable to the effects of environmental perturbations, particularly during warmer periods of the year

    Humanities for medical students? A qualitative study of a medical humanities curriculum in a medical school program

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    BACKGROUND: Today, there is a trend towards establishing the medical humanities as a component of medical education. However, medical humanities programs that exist within the context of a medical school can be problematic. The aim of this study was to explore problems that can arise with the establishment of a medical humanities curriculum in a medical school program. METHODS: Our theoretical approach in this study is informed by derridean deconstruction and by post-structuralist analysis. We examined the ideology of the Humanities and Medicine program at Lund University, Sweden, the practical implementation of the program, and how ideology and practice corresponded. Examination of the ideology driving the humanities and medicine program was based on a critical reading of all available written material concerning the Humanities and Medicine project. The practice of the program was examined by means of a participatory observation study of one course, and by in-depth interviews with five students who participated in the course. Data was analysed using a hermeneutic editing approach. RESULTS: The ideological language used to describe the program calls it an interdisciplinary learning environment but at the same time shows that the conditions of the program are established by the medical faculty's agenda. In practice, the "humanities" are constructed, defined and used within a medical frame of reference. Medical students have interesting discussions, acquire concepts and enjoy the program. But they come away lacking theoretical structure to understand what they have learned. There is no place for humanities students in the program. CONCLUSION: A challenge facing cross-disciplinary programs is creating an environment where the disciplines have equal standing and contribution

    Measurement of the Relative Branching Fraction of ÎĄ(4S)\Upsilon(4S) to Charged and Neutral B-Meson Pairs

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    We analyze 9.7 x 10^6 B\bar{B}$ pairs recorded with the CLEO detector to determine the production ratio of charged to neutral B-meson pairs produced at the Y(4S) resonance. We measure the rates for B^0 -> J/psi K^{(*)0} and B^+ -> J/psi K^{(*)+} decays and use the world-average B-meson lifetime ratio to extract the relative widths f+-/f00 = Gamma(Y(4S) -> B+B-)/Gamma(Y(4S) -> B0\bar{B0}) = = 1.04 +/- 0.07(stat) +/- 0.04(syst). With the assumption that f+- + f00 = 1, we obtain f00 = 0.49 +/- 0.02(stat) +/- 0.01(syst) and f+- = 0.51 +/- 0.02(stat) +/- 0.01(syst). This production ratio and its uncertainty apply to all exclusive B-meson branching fractions measured at the Y(4S) resonance.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN
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