3,994 research outputs found

    The dynamics and kinematics of the coastal boundary layer off Long Island

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    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution December 1980Data from the COBOLT experiment, which investigated the first 12 km off Long Island's south shore, are analyzed and discussed. Moored current meter records indicate that the nearshore flow field is strongly polarized in the alongshore direction and its fluctuations are well correlated with local meteorological forcing. Complex empirical orthogonal function analysis suggests that subtidal velocity fluctuations are barotropic in nature and are strongly influenced by bottom friction. Wind-related inertial currents were observed within the coastal boundary layer (CBL) under favorable meteorological and hydrographical conditions. The magnitude of these oscillations increases with distance from shore, and they display a very clear 180° phase difference between surface and bottom layers. Nearshore inertial oscillations of both velocity and salinity records appear to lead those further seaward, suggesting local generation and subsequent radiation away from the coast. The response of the coastal zone to impulsive wind forcing is discussed using simple slab and two-layer models, and the behavior of the nearshore current field examined. The major features of the observed inertial motions are in good qualitative agreement with model predictions. It is found that, in a homogeneous domain, the coastal boundary condition effectively prohibits inertial currents over the entire coastal zone. In the presence of stratification the offshore extent of this prohibition is greatly reduced and significant inertial currents may occur within one or two internal deformation radii of the coast. The "coastal effect", in the form of surface and interfacial waves which propagate away from the coast, modifies the "pure" inertial response as it would exist far from shore. The kinematics of this process is such that a 180° phase difference between currents in the two layers is characteristic of the entire coastal zone even before the internal wave has had time to traverse the CBL. It is also suggested that, for positions seaward of several internal deformation radii, interference between the surface and internal components of the coastal response will cause maximum inertial amplitudes to occur for t > x/c2, where c2 is the phase speed of the internal disturbance. The hydrographic structure of the CBL is observed to undergo frequent homogenization. These events are related to both advective and mixing processes. Horizontal and vertical exchange coefficients are estimated from the data, and subsequently used in a diffusive model which accurately reproduces the observed mean density distribution in the nearshore zone. Dynamic balance calculations are performed which indicate that the subtidal cross-shore momentum balance is very nearly geostrophic. The calculations also suggest that the longshore balance may be reasonably represented by a steady, linear equation of motion which includes surface and bottom stresses. Evidence is presented which shows that variations in the longshore wind-stress component are primarily responsible for the energetic fluctuations in the sea surface slope along Long Island. Depth-averaged velocities characteristically show net offshore transport in the study area, and often display dramatic longshore current reversals with distance from shore. These observations are interpreted in terms of a steady circulation model which includes realistic nearshore topography. Model results suggest that longshore current reversals within the CBL may be limited to the eastern end of Long Island, and that this unusual flow pattern is a consequence of flow convergence related to the presence of Long Island Sound.This work was supported by the Department of Energy through contract no. DE-AC02-EVI0005 entitled Coastal-Shelf Transport and Diffusion

    Final evaluation of the saving gateway 2 pilot: main report

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    The Saving Gateway is a government initiative aimed at encouraging savings behaviour among people who do not usually save. Each pound placed into a Saving Gateway account is matched by the government at a certain rate and up to a monthly contribution limit. Matching provides a transparent and understandable incentive for eligible individuals to place funds in an account

    A Modification of the Response Method of Tidal Analysis

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    An easily implemented extension of the standard response method of tidal analysis is outlined. The modification improves the extraction of both the steady and the tidal components from problematic time series by calculating tidal response weights uncontaminated by missing or anomalous data. Examples of time series containing data gaps and anomalous events are analyzed to demonstrate the applicability and advantage of the proposed method

    Humoral autoimmunity after solid organ transplantation: Germinal ideas may not be natural

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    Non-HLA antibody responses following solid organ transplantation have become increasingly emphasised, with several large clinical series suggesting that such responses contribute to late graft failure. Many of the responses described recognise both recipient and donor moieties of the target antigen and thus represent auto-, rather than allo-immunity. Within this rapidly evolving field, many questions remain unanswered: what triggers the response; how innate and adaptive humoral autoimmunity integrate; and most pressingly, how autoimmunity contributes to graft damage and its relationship to other effector mechanisms of graft rejection. This review summarises recent clinical and experimental studies of humoral autoimmunity in transplant rejection, and considers some of the answers to these questions

    Large-scale general practice in England: what can we learn from the literature?

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    Traditional general practice is changing. Three-quarters of practices are now working collaboratively in larger-scale organisations – albeit with varying degrees of ambition and organisational integration. Policy-makers and practitioners have high hopes for these organisations and their potential to transform services both within primary care and beyond. But can we be confident that they can live up to these expectations? This report presents findings of an extensive literature review on the subject of large-scale general practice, and contributes to a stream of work by the Nuffield Trust in this area, details of which can be found at: www.nuffieldtrust.org.uk/large-scale-general-practice

    Exploring Factors Associated With Physical Activity in Older Adults: An Ecological Approach

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    According to ecological models of behavior, the physical environment can influence physical activity engagement by a series of mediating and moderating processes. This study tested such a model to identify factors relevant to older adults' engagement in moderate-vigorous physical activity. Sociodemographic, psychological, physical, and environmental factors were assessed in 432 Western Australians aged 60 and older. Moderate-vigorous physical activity was measured objectively using accelerometers. No environmental variables were related to engagement in moderate-vigorous physical activity either directly or indirectly. However, various individual-level factors were significant, indicating that these may be more important than environmental factors in locations such as Australia that have generally conducive environments and ambient conditions

    Exploring the use of strategic frameworks in dental practice

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    This paper explores the use of strategic frameworks in NHS and private dental practice. It reviews the policy context of dentistry and suggests the challenges in this context will require dental practices to prioritise understanding and engagement with a strategic approach. A strategic approach will be required in order to enhance and improve performance. Two specific strategic frameworks will be explored in terms of their relevance to NHS and private dental practic
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