2,773 research outputs found
Orbit transfer rocket engine integrated control and health monitoring system technology readiness assessment
The objectives of this task were to: (1) estimate the technology readiness of an integrated control and health monitoring (ICHM) system for the Aerojet 7500 lbF Orbit Transfer Vehicle engine preliminary design assuming space based operations; and (2) estimate the remaining cost to advance this technology to a NASA defined 'readiness level 6' by 1996 wherein the technology has been demonstrated with a system validation model in a simulated environment. The work was accomplished through the conduct of four subtasks. In subtask 1 the minimally required functions for the control and monitoring system was specified. The elements required to perform these functions were specified in Subtask 2. In Subtask 3, the technology readiness level of each element was assessed. Finally, in Subtask 4, the development cost and schedule requirements were estimated for bringing each element to 'readiness level 6'
Maternal Age and Infant Mortality: A Test of the Wilcox-Russell Hypothesis
It has been argued (e.g., the Wilcox-Russell hypothesis) that (low) birth weight is a correlate of adverse birth outcomes but is not on the “causal” pathway to infant mortality. However, the US national policy for reducing infant mortality is to reduce low birth weight. If these theoretical views are correct, lowering the rate of low birth weight may have little effect on infant mortality. In this paper, the authors use the “covariate density defined mixture of logistic regressions” method to formally test the Wilcox-Russell hypothesis that a covariate which influences birth weight, in this case maternal age, can influence infant mortality directly but not indirectly through birth weight. The authors analyze data from 8 populations in New York State (1985–1988). The results indicate that among the populations examined, 1) maternal age significantly influences the birth weight distribution and 2) maternal age also affects infant mortality directly, but 3) the influence of maternal age on the birth weight distribution has little or no effect on infant mortality, because the birth-weight-specific mortality curve shifts accordingly to compensate for changes in the birth weight distribution. These results tend to support the Wilcox-Russell hypothesis for maternal age
Degenerate dispersive equations arising in the study of magma dynamics
An outstanding problem in Earth science is understanding the method of
transport of magma in the Earth's mantle. Models for this process, transport in
a viscously deformable porous media, give rise to scalar degenerate,
dispersive, nonlinear wave equations. We establish a general local
well-posedness for a physical class of data (roughly ) via fixed point
methods. The strategy requires positive lower bounds on the solution. This is
extended to global existence for a subset of possible nonlinearities by making
use of certain conservation laws associated with the equations. Furthermore, we
construct a Lyapunov energy functional, which is locally convex about the
uniform state, and prove (global in time) nonlinear dynamic stability of the
uniform state for any choice of nonlinearity. We compare the dynamics to that
of other problems and discuss open questions concerning a larger range of
nonlinearities, for which we conjecture global existence.Comment: 27 Pages, 7 figures are not present in this version. See
http://www.columbia.edu/~grs2103/ for a PDF with figures. Submitted to
Nonlinearit
Mechanically-Deployed Hypersonic Decelerator and Conformal Ablator Technologies for Mars Missions
The concept of a mechanically deployable hypersonic decelerator, developed initially for high mass (~40 MT) human Mars missions, is currently funded by OCT for technology maturation. The ADEPT (Adaptive, Deployable Entry and Placement Technology) project has broad, game-changing applicability to in situ science missions to Venus, Mars, and the Outer Planets. Combined with maturation of conformal ablator technology (another current OCT investment), the two technologies provide unique low mass mission enabling capabilities otherwise not achievable by current rigid aeroshell or by inflatables. If this abstract is accepted, we will present results that illustrate the mission enabling capabilities of the mechanically deployable architecture for: (1) robotic Mars (Discovery or New Frontiers class) in the near term; (2) alternate approaches to landing MSL-class payloads, without the need for supersonic parachute or lifting entry, in the mid-term; and (3) Heavy mass and human missions to Mars in the long term
Optimal NHS service delivery to care homes: a realist evaluation of the features and mechanisms that support effective working for the continuing care of older people in residential settings
Background
Care homes are the institutional providers of long-term care for older people. The OPTIMAL study argued that it is probable that there are key activities within different models of health-care provision that are important for residents’ health care.
Objectives
To understand ‘what works, for whom, why and in what circumstances?’. Study questions focused on how different mechanisms within the various models of service delivery act as the ‘active ingredients’ associated with positive health-related outcomes for care home residents.
Methods
Using realist methods we focused on five outcomes: (1) medication use and review; (2) use of out-of-hours services; (3) hospital admissions, including emergency department attendances and length of hospital stay; (4) resource use; and (5) user satisfaction. Phase 1: interviewed stakeholders and reviewed the evidence to develop an explanatory theory of what supported good health-care provision for further testing in phase 2. Phase 2 developed a minimum data set of resident characteristics and tracked their care for 12 months. We also interviewed residents, family and staff receiving and providing health care to residents. The 12 study care homes were located on the south coast, the Midlands and the east of England. Health-care provision to care homes was distinctive in each site.
Findings
Phase 1 found that health-care provision to care homes is reactive and inequitable. The realist review argued that incentives or sanctions, agreed protocols, clinical expertise and structured approaches to assessment and care planning could support improved health-related outcomes; however, to achieve change NHS professionals and care home staff needed to work together from the outset to identify, co-design and implement agreed approaches to health care. Phase 2 tested this further and found that, although there were few differences between the sites in residents’ use of resources, the differences in service integration between the NHS and care homes did reflect how these institutions approached activities that supported relational working. Key to this was how much time NHS staff and care home staff had had to learn how to work together and if the work was seen as legitimate, requiring ongoing investment by commissioners and engagement from practitioners. Residents appreciated the general practitioner (GP) input and, when supported by other care home-specific NHS services, GPs reported that it was sustainable and valued work. Access to dementia expertise, ongoing training and support was essential to ensure that both NHS and care home staff were equipped to provide appropriate care.
Limitations
Findings were constrained by the numbers of residents recruited and retained in phase 2 for the 12 months of data collection.
Conclusions
NHS services work well with care homes when payments and role specification endorse the importance of this work at an institutional level as well as with individual residents. GP involvement is important but needs additional support from other services to be sustainable. A focus on strategies that promote co-design-based approaches between the NHS and care homes has the potential to improve residents’ access to and experience of health care.
Funding
The National Institute for Health Research Health Services and Delivery Research programme
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The feasibility of increasing physical activity in care home residents: Active Residents in Care Homes (ARCH) programme.
OBJECTIVES: Maintaining physical activity for older residents in care homes maximises their physical and mental health and wellbeing, independence, dignity and quality of life. Unfortunately, most residents do not participate in regular physical activity. Active Residents in Care Homes, ARCH, was designed to increase physical activity by facilitating whole-system change in a care home. We evaluated whether ARCH can be delivered, its effects on resident's physical activity, wellbeing and costs. DESIGN: Feasibility study. SETTING: Three residential care homes. PARTICIPANTS: Care home residents and staff. INTERVENTION: Occupational and physiotherapists implemented ARCH over 4 months with an 8-month follow-up. MAIN OUTCOME MEASURES: Assessment of Physical Activity, Pool Activity Level, EQ5D-5L, Dementia Care Mapping, cost of implementing ARCH, health and social care utilisation. RESULTS: After implementing ARCH, residents displayed more positive behaviours, better mood and engagement and higher physical activity levels, but these improvements were not sustained at 8-month follow-up. The cost (2016 prices) of implementing ARCH was £61,037, which equates to £1,650/resident. Healthcare utilisation was £295/resident (SD320) in the 4 months prior to ARCH, £308/resident (SD406) during the 4-month implementation and £676/resident (SD438) in the 8-month follow-up. CONCLUSIONS: The ARCH programme can be delivered, it may have some short-term benefits and is affordable. Rather than have unrealistic increases in the health and longevity of older care home residents, ARCH may slow the decline in physical, mental and emotional well-being usually seen in older people in care homes, return some dignity and improve their quality of life in their last months or years
Lymphocyte subsets and the role of Th1/Th2 balance in stressed chronic pain patients
Background: The complex regional pain syndrome (CRPS) and fibromyalgia (FM) are chronic pain syndromes occurring in highly stressed individuals. Despite the known connection between the nervous system and immune cells, information on distribution of lymphocyte subsets under stress and pain conditions is limited. Methods: We performed a comparative study in 15 patients with CRPS type I, 22 patients with FM and 37 age- and sex-matched healthy controls and investigated the influence of pain and stress on lymphocyte number, subpopulations and the Th1/Th2 cytokine ratio in T lymphocytes. Results: Lymphocyte numbers did not differ between groups. Quantitative analyses of lymphocyte subpopulations showed a significant reduction of cytotoxic CD8+ lymphocytes in both CRPS (p < 0.01) and FM (p < 0.05) patients as compared with healthy controls. Additionally, CRPS patients were characterized by a lower percentage of IL-2-producing T cell subpopulations reflecting a diminished Th1 response in contrast to no changes in the Th2 cytokine profile. Conclusions: Future studies are warranted to answer whether such immunological changes play a pathogenetic role in CRPS and FM or merely reflect the consequences of a pain-induced neurohumoral stress response, and whether they contribute to immunosuppression in stressed chronic pain patients. Copyright (c) 2008 S. Karger AG, Basel
Experimental evaluation of an adaptive Joule--Thomson cooling system including silicon-microfabricated heat exchanger and microvalve components
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98726/1/JVA021005.pd
Normal scaling in globally conserved interface-controlled coarsening of fractal clusters
Globally conserved interface-controlled coarsening of fractal clusters
exhibits dynamic scale invariance and normal scaling. This is demonstrated by a
numerical solution of the Ginzburg-Landau equation with a global conservation
law. The sharp-interface limit of this equation is volume preserving motion by
mean curvature. The scaled form of the correlation function has a power-law
tail accommodating the fractal initial condition. The coarsening length
exhibits normal scaling with time. Finally, shrinking of the fractal clusters
with time is observed. The difference between global and local conservation is
discussed.Comment: 4 pages, 3 eps figure
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