Vegetation and hydrologic influences on carbon and nitrogen in subsurface water of a forested riparian wetland

Vegetation communities affect carbon and nitrogen dynamics in the subsurface water of mineral wetlands through the quality of their litter, their uptake of nutrients, root exudation and their effects on redox potential. However, vegetation influence on subsurface nutrient dynamics is often overshadowed by the influences of hydrology, soils and geology on nutrient dynamics. The effects of vegetation communities on carbon and nitrogen dynamics are important to consider when managing land that may change vegetation type or quantity so that wetland ecosystem functions can be retained. This study was established to determine the magnitude of the influences and interaction of vegetation cover and hydrology, in the form of water table fluctuations, on carbon and nitrogen dynamics in a northern forested riparian wetland. Dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), nitrate (NO3-) and ammonium (NH4+) concentrations were collected from a piezometer network in four different vegetation communities and were found to show complex responses to vegetation cover and water table fluctuations. Dissolved organic carbon, DIC, NO3- and NH4+ concentrations were influenced by forest vegetation cover. Both NO3- and NH4+ were also influenced by water table fluctuations. However, for DOC and NH4+ concentrations there appeared to be more complex interactions than were measured by this study. The results of canonical correspondence analysis (CCA) and analysis of variance (ANOVA) did not correspond in relationship to the significance of vegetation communities. Dissolved inorganic carbon was influenced by an interaction between vegetation cover and water table fluctuations. More hydrological information is needed to make stronger conclusions about the relationship between vegetation and hydrology in controlling carbon and nitrogen dynamics in a forested riparian wetland

Simulations of methane-air flames using ISAT and ANN

Large-eddy simulations (LES) of turbulent flames with detailed finite-rate kinetics is currently computationally infeasible due to the enormous cost associated with computation of reaction kinetics. Recently, an In-Situ Adaptive Tabulation (ISAT) methodology was shown to reduce the cost of direct integration considerably. However, ISAT tables require significant on-line storage in memory and may result in restriction on massivelly parallel systems. Furthermore, application of ISAT in LES requires reevaluation of the tree structure and the access/retrieval process. Here, issues regarding the use of ISAT in a LES are discussed. Then, a storage-efficient Artificial Neural Network (ANN) is trained using ISAT data and used to simulate turbulent premixed flames in both the thin-reaction-zone and flamelet regimes. Finally, the issues to be addressed in order to apply this combined ISAT/ANN methodology for full-scale LES of reacting flows are discussed

Parallel simulations of reacting two-phase flows - A DoD Grand Challenge progress report

Parallel simulation of unsteady turbulent combustion is carried out for a range of precursor test problems leading to the development of a new methodology for reacting two-phase flows. Simulations are carried out using large-eddy simulations (LES) which allows full spatio-temporal resolution of all scales larger than the grid resolution with the unresolved small-scales modeled by a localized dynamic one-equation subgrid models. For two-phase applications, Lagrangian tracking of a range of droplets is carried out and is fully coupled to the Eulerian gas phase flow. An extension of this approach to accurately deal with small-scale scalar mixing and chemical reactions has been carried out using an innovative model that is implemented within each LES cell, to account for the effects of small-scale mixing and molecular diffusion on the chemical processes. The first year's effort focused on validating this methodology using both simple and complex test configurations. Highly optimized parallel LES codes are used for these studies. In addition to parallel scaleup data, results discussed in this paper include stagnation point premixed flame, opposed jet diffusion flame, highly swirling premixed flame in a General Electric combustor and two-phase mixing and vaporization in mixing layers. Comparison with experimental data wherever possible, clearly demonstrates the unique capabilities of the new subgrid combustion LES model

The epidemiology of injuries across the weight-training sports

Background: Weight-training sports, including weightlifting, powerlifting, bodybuilding, strongman, Highland Games, and CrossFit, are weight-training sports that have separate divisions for males and females of a variety of ages, competitive standards, and bodyweight classes. These sports may be considered dangerous because of the heavy loads commonly used in training and competition. Objectives: Our objective was to systematically review the injury epidemiology of these weight-training sports, and, where possible, gain some insight into whether this may be affected by age, sex, competitive standard, and bodyweight class. Methods: We performed an electronic search using PubMed, SPORTDiscus, CINAHL, and Embase for injury epidemiology studies involving competitive athletes in these weight-training sports. Eligible studies included peer-reviewed journal articles only, with no limit placed on date or language of publication. We assessed the risk of bias in all studies using an adaption of the musculoskeletal injury review method. Results: Only five of the 20 eligible studies had a risk of bias score ≥75 %, meaning the risk of bias in these five studies was considered low. While 14 of the studies had sample sizes >100 participants, only four studies utilized a prospective design. Bodybuilding had the lowest injury rates (0.12–0.7 injuries per lifter per year; 0.24–1 injury per 1000 h), with strongman (4.5–6.1 injuries per 1000 h) and Highland Games (7.5 injuries per 1000 h) reporting the highest rates. The shoulder, lower back, knee, elbow, and wrist/hand were generally the most commonly injured anatomical locations; strains, tendinitis, and sprains were the most common injury type. Very few significant differences in any of the injury outcomes were observed as a function of age, sex, competitive standard, or bodyweight class. Conclusion: While the majority of the research we reviewed utilized retrospective designs, the weight-training sports appear to have relatively low rates of injury compared with common team sports. Future weight-training sport injury epidemiology research needs to be improved, particularly in terms of the use of prospective designs, diagnosis of injury, and changes in risk exposure

Simulation in coronary artery anastomosis early in cardiothoracic surgical residency training: The Boot Camp experience

We evaluated focused training in coronary artery anastomosis with a porcine heart model and portable task station

On LEM/LES methodology for two-phase flows

A two-phase subgrid combustion model developed earlier has been evaluated for applicability in large-eddy simulations (LES). Direct Numerical Simulations (DNS) of two-phase isotropic turbulence in the presence of passive, momentum-coupled and vaporizing droplets has been extensively studied to form a base-line database. Current DNS results agree with earlier studies and show that the presence of droplets increase the kinetic energy and dissipation at the small scales. LES for these same cases were also carried out to investigate what modifications are needed to incorporate the small-scale turbulence modifications seen in DNS of two-phase flows. LES subgrid modeling for two-phase mixing within the context of the new subgrid combustion model is also addressed

Cornish identities and migration: a multi-scalar approach

The definitive version is available at www.blackwell-synergy.com. 24 month embargo by the publisher. Article will be released July 2009.In this article we argue that theories of transnationalism have value in exploring the historical context of migration and that historical contexts help to shape such theoretical conceptualizations. Historians of migration have now begun to engage more directly with the literature of transnationalism, focusing on the networks that linked settler and home communities. Here we add to this by examining a nineteenth-century migrant community from a British region through the lens of transnationalism, applying the concept to the case of the Cornish, whose economic specialization produced culturally distinct Cornish communities on the mining frontiers of North America, Australia and South Africa. In doing so, we bring together the issues of scale and time. We review the multiple levels of the Cornish transnational space of the late nineteenth century, which exhibited aspects of both core transnationalism and translocalism. This waned, but in the later twentieth century, a renewed interest in a transnational Cornish identity re-emerged, articulating with changing identity claims in Cornwall itself. To capture better the experience of the Cornish over these two very different phases of transnationalism we identify another subset of transnationalism - that of transregionalism.Leverhulme Trus