3,994 research outputs found
The dynamics and kinematics of the coastal boundary layer off Long Island
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
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
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
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?
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
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
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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