1,364 research outputs found
Topography Experiment (TOPEX) Software Document Series Volume 7: TOPEX Mission Radar Altimeter Engineering Assessment Report, February 1994
This document describes the GSFC/WFF analysis of the on-orbit engineering data from the TOPEX radar altimeter, to establish altimeter performance. In accordance with Project guidelines, neither surface truth nor precision orbital data are used for the engineering assessment of the altimeter. The use of such data would imply not only a more intensive and complete performance evaluation, but also a calibration. Such evaluations and.calibrations are outside the scope of this document and will be presented in a separate Verification Report
A simple ocean bottom hydrophone with 200 megabyte data capacity
The Woods Hole Ocean Bottom Hydrophone instrument records the digitized output of a single hydrophone sensor at rates
between 250 and 1200 samples per second with a dynamic range of 98 dB and can be deployed at depths to 600 meters. The unit's
200 megabyte disk recorder allows operation for periods up to 5 days. Designed for typical marine seismic refraction operations the
unit is reliable and simple to deploy and recover. A detailed description is provided of the instrument design and application including
transfer function, clock accuracy, data format, sample data and power requirements.Funding provided by the National Science Foundation under Grant
Nos. OCE-9019918 and OCE-8917628
Tensile strained membranes for cavity optomechanics
We investigate the optomechanical properties of tensile-strained ternary
InGaP nanomembranes grown on GaAs. This material system combines the benefits
of highly strained membranes based on stoichiometric silicon nitride, with the
unique properties of thin-film semiconductor single crystals, as previously
demonstrated with suspended GaAs. Here we employ lattice mismatch in epitaxial
growth to impart an intrinsic tensile strain to a monocrystalline thin film
(approximately 30 nm thick). These structures exhibit mechanical quality
factors of 2*10^6 or beyond at room temperature and 17 K for eigenfrequencies
up to 1 MHz, yielding Q*f products of 2*10^12 Hz for a tensile stress of ~170
MPa. Incorporating such membranes in a high finesse Fabry-Perot cavity, we
extract an upper limit to the total optical loss (including both absorption and
scatter) of 40 ppm at 1064 nm and room temperature. Further reductions of the
In content of this alloy will enable tensile stress levels of 1 GPa, with the
potential for a significant increase in the Q*f product, assuming no
deterioration in the mechanical loss at this composition and strain level. This
materials system is a promising candidate for the integration of strained
semiconductor membrane structures with low-loss semiconductor mirrors and for
realizing stacks of membranes for enhanced optomechanical coupling.Comment: 10 pages, 3 figure
Seeking ambulance treatment for ‘primary care’ problems:a qualitative systematic review of patient, carer and professional perspectives
ObjectivesTo understand the reasons behind, and experience of, seeking and receiving emergency ambulance treatment for a ‘primary care sensitive’ condition.DesignA comprehensive, qualitative systematic review. Medline, Embase, PsychInfo, Cumulative Index of Nursing and Allied Health, Health Management Information Systems, Healthcare Management Information Consortium, OpenSigle, EThOS and Digital Archive of Research Theses databases were systematically searched for studies exploring patient, carer or healthcare professional interactions with ambulance services for ‘primary care sensitive’ problems. Studies using wholly qualitative approaches or mixed-methods studies with substantial use of qualitative techniques in both the methods and analysis sections were included. An analytical thematic synthesis was undertaken, using a line-by-line qualitative coding method and a hierarchical inductive approach.ResultsOf 1458 initial results, 33 studies met the first level (relevance) inclusion criteria, and six studies met the second level (methodology and quality) criteria. The analysis suggests that patients define situations worthy of ‘emergency’ ambulance use according to complex socioemotional factors, as well as experienced physical symptoms. There can be a mismatch between how patients and professionals define ‘emergency’ situations. Deciding to call an ambulance is a process shaped by practical considerations and a strong emotional component, which can be influenced by the views of caregivers. Sometimes the value of a contact with the ambulance service is principally in managing this emotional component. Patients often wish to hand over responsibility for decisions when experiencing a perceived emergency. Feeling empowered to take control of a situation is a highly valued aspect of ambulance care.ConclusionsWhen responding to a request for ‘emergency’ help for a low-acuity condition, urgent-care services need to be sensitive to how the patient's emotional and practical perception of the situation may have shaped their decision-making and the influence that carers may have had on the process. There may be novel ways to deliver some of the valued aspects of urgent care, more geared to the resource-limited environment.</jats:sec
Lines, Circles, Planes and Spheres
Let be a set of points in , no three collinear and not
all coplanar. If at most are coplanar and is sufficiently large, the
total number of planes determined is at least . For similar conditions and
sufficiently large , (inspired by the work of P. D. T. A. Elliott in
\cite{Ell67}) we also show that the number of spheres determined by points
is at least , and this bound is best
possible under its hypothesis. (By , we are denoting the
maximum number of three-point lines attainable by a configuration of
points, no four collinear, in the plane, i.e., the classic Orchard Problem.)
New lower bounds are also given for both lines and circles.Comment: 37 page
'Primary care sensitive' situations that result in an ambulance attendance:a Conversation Analytic study of UK emergency 999 call recordings
Isotropic-nematic phase transition in suspensions of filamentous virus and the neutral polymer Dextran
We present an experimental study of the isotropic-nematic phase transition in
an aqueous mixture of charged semi-flexible rods (fd virus) and neutral polymer
(Dextran). A complete phase diagram is measured as a function of ionic strength
and polymer molecular weight. At high ionic strength we find that adding
polymer widens the isotropic-nematic coexistence region with polymers
preferentially partitioning into the isotropic phase, while at low ionic
strength the added polymer has no effect on the phase transition. The nematic
order parameter is determined from birefringence measurements and is found to
be independent of polymer concentration (or equivalently the strength of
attraction). The experimental results are compared with the existing
theoretical predictions for the isotropic-nematic transition in rods with
attractive interactions.Comment: 8 Figures. To be published in Phys. Rev. E. For more information see
http://www.elsie.brandeis.ed
Ambulance use for ‘primary care’ problems ::an ethnographic study of seeking and providing help in a UK ambulance service
Coronavirus and Pasteurella infections in bovine shipping fever pneumonia and Evans\u27 criteria for causation
Respiratory tract infections with viruses and Pasteurella spp. were determined sequentially among 26 cattle that died during two severe epizootics of shipping fever pneumonia. Nasal swab and serum samples were collected prior to onset of the epizootics, during disease progression, and after death, when necropsies were performed and lung samples were collected. Eighteen normal control cattle also were sampled at the beginning of the epizootics as well as at weekly intervals for 4 weeks. Respiratory bovine coronaviruses (RBCV) were isolated from nasal secretions of 21 and 25 cattle before and after transport. Two and 17 cattle nasally shed Pasteurella spp. before and after transport, respectively. RBCV were isolated at titers of 1 x 103 to 1.2 x 107 PFU per g of lung tissue from 18 cattle that died within 7 days of the epizootics, but not from the lungs of the remaining cattle that died on days 9 to 36. Twenty-five of the 26 lung samples were positive for Pasteurella spp., and their CFU ranged between 4.0 x 105 and 2.3 x 109 per g. Acute and subacute exudative, necrotizing lobar pneumonia characterized the lung lesions of these cattle with a majority of pneumonic lung lobes exhibiting fibronecrotic and exudative changes typical of pneumonic pasteurellosis, but other lung lobules had histological changes consisting of bronchiolitis and alveolitis typical of virus-induced changes. These cattle were immunologically naive to both infectious agents at the onset of the epizootics, but those that died after day 7 had rising antibody titers against RBCV and Pasteurella haemolytica. In contrast, the 18 clinically normal and RBCV isolation-negative cattle had high hemagglutinin inhibition antibody titers to RBCV from the beginning, while their antibody responses to P. haemolytica antigens were delayed. Evans\u27 criteria for causation were applied to our findings because of the multifactorial nature of shipping fever pneumonia. This analysis identified RBCV as the primary inciting cause in these two epizootics. These viruses were previously not recognized as a causative agent in this complex respiratory tract disease of cattle
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