17,477 research outputs found
An improved pulse-height analyzer for energetic particle measurements in the upper atmosphere
An energetic particle spectrometer for measurements in the upper atmosphere by rocket is described. The system has two methods of processing data. One is a staircase generator using threshold detectors; the other is a peak detector. The system incorporates a logarithmic converter for better resolution at low amplitudes and better use of telemetry channels. The circuits are described and calibration procedures are given. Modifications are recommended for high flux environments. Appendices cover sampling error in the peak detector and modifications made to the receiver of the propagation experiment
A study for development of aerothermodynamic test model materials and fabrication technique
A literature survey, materials reformulation and tailoring, fabrication problems, and materials selection and evaluation for fabricating models to be used with the phase-change technique for obtaining quantitative aerodynamic heat transfer data are presented. The study resulted in the selection of two best materials, stycast 2762 FT, and an alumina ceramic. Characteristics of these materials and detailed fabrication methods are presented
Readmission Rates and Their Impact on Hospital Financial Performance: A Study of Washington Hospitals
This longitudinal study examines whether readmission rates, made transparent through Hospital Compare, affect hospital financial performance by examining 98 hospitals in the State of Washington from 2012 to 2014. Readmission rates for acute myocardial infarction (AMI), pneumonia (PN), and heart failure (HF) were examined against operating revenues per patient, operating expenses per patient, and operating margin. Using hospital-level fixed effects regression on 276 hospital year observations, the analysis indicated that a reduction in AMI readmission rates is related with increased operating revenues as expenses associated with costly treatments related with unnecessary readmissions are avoided. Additionally, reducing readmission rates is related with an increase in operating expenses. As a net effect, increased PN readmission rates may show marginal increase in operating margin because of the higher operating revenues due to readmissions. However, as readmissions continue to happen, a gradual increase in expenses due to greater use of resources may lead to decreased profitability
Experimental and analytical study of thermal acoustic oscillations
The thermal acoustic oscillations (TAO) data base was expanded by running a large number of tubes over a wide range of parameters known to affect the TAO phenomenon. These parameters include tube length, wall thickness, diameter, material, insertion length and length-to-diameter ratio. Emphasis was placed on getting good boiloff data. A large quantity of data was obtained, reduced, correlated and analyzed and is presented. Also presented are comparisons with previous types of correlations. These comparisons show that the boiloff data did not correlate with intensity. The data did correlate in the form used by Rott, that is boiloff versus TAO pressure squared times frequency to the one-half power. However, this latter correlation required a different set of correlation constants, slope and intercept, for each tube tested
Review: emerging concepts in the pathogenesis of tendinopathy
Tendinopathy is a common clinical problem and has a significant disease burden attached, not only in terms of health care costs, but also for patients directly in terms of time off work and impact upon quality of life. Controversy surrounds the pathogenesis of tendinopathy, however the recent systematic analysis of the evidence has demonstrated that many of the claims of an absence of inflammation in tendinopathy were more based around belief than robust scientific data. This review is a summary of the emerging research in this topical area, with a particular focus on the role of neuronal regulation and inflammation in tendinopathy
Some considerations on coastal processes relevant to sea level rise
The effects of potential sea level rise on the shoreline and shore environment
have been briefly examined by considering the interactions between sea level rise and
relevant coastal processes. These interactions have been reviewed beginning with a
discussion of the need to reanalyze previous estimates of eustatic sea level rise and
compaction effects in water level measurement. This is followed by considerations on
sea level effects on coastal and estuarine tidal ranges, storm surge and water level
response, and interaction with natural and constructed shoreline features. The
desirability to reevaluate the well known Bruun Rule for estimating shoreline recession
has been noted. The mechanics of ground and surface water intrusion with reference to
sea level rise are then reviewed. This is followed by sedimentary processes in the
estuaries including wetland response. Finally comments are included on some probable
effects of sea level rise on coastal ecosystems.
These interactions are complex and lead to shoreline evolution (under a sea level
rise) which is highly site-specific. Models which determine shoreline change on the
basis of inundation of terrestrial topography without considering relevant coastal
processes are likely to lead to erroneous shoreline scenarios, particularly where the
shoreline is composed of erodible sedimentary material.
With some exceptions, present day knowledge of shoreline response to hydrodynamic
forcing is inadequate for long-term quantitative predictions. A series of interrelated
basic and applied research issues must be addressed in the coming decades to
determine shoreline response to sea level change with an acceptable degree of
confidence. (PDF contains 189 pages.
Recurrent cerebellar architecture solves the motor-error problem
Current views of cerebellar function have been heavily influenced by the models of Marr and Albus, who suggested that the climbing fibre input to the cerebellum acts as a teaching signal for motor learning. It is commonly assumed that this teaching signal must be motor error (the difference between actual and correct motor command), but this approach requires complex neural structures to estimate unobservable motor error from its observed sensory consequences.
We have proposed elsewhere a recurrent decorrelation control architecture in which Marr-Albus models learn without requiring motor error. Here, we prove convergence for this architecture and demonstrate important advantages for the modular control of systems with multiple degrees of freedom. These results are illustrated by modelling adaptive plant compensation for the three-dimensional vestibular ocular reflex. This provides a functional role for recurrent cerebellar connectivity, which may be a generic anatomical feature of projections between regions of cerebral and cerebellar cortex
Current-induced nuclear-spin activation in a two-dimensional electron gas
Electrically detected nuclear magnetic resonance was studied in detail in a
two-dimensional electron gas as a function of current bias and temperature. We
show that applying a relatively modest dc-current bias, I_dc ~ 0.5 microAmps,
can induce a re-entrant and even enhanced nuclear spin signal compared with the
signal obtained under similar thermal equilibrium conditions at zero current
bias. Our observations suggest that dynamic nuclear spin polarization by small
current flow is possible in a two-dimensional electron gas, allowing for easy
manipulation of the nuclear spin by simple switching of a dc current.Comment: 5 pages, 3 fig
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