9,681 research outputs found
A comparison of methods for calculating general practice level socioeconomic deprivation
Background: A measure of the socioeconomic deprivation experienced by the registered patient population of a general practice is of interest because it can be used to explore the association between deprivation and a wide range of other variables measured at practice level. If patient level geographical data are available a population weighted mean area-based deprivation score can be calculated for each practice. In the absence of these data, an area-based deprivation score linked to the practice postcode can be used as an estimate of the socioeconomic deprivation of the practice population. This study explores the correlation between Index of Multiple Deprivation 2004 (IMD) scores linked to general practice postcodes (main surgery address alone and main surgery plus any branch surgeries), practice population weighted mean IMD scores, and practice level mortality (aged 1 to 75 years, all causes) for 38 practices in Rotherham UK.
Results: Population weighted deprivation scores correlated with practice postcode based scores (main surgery only, Pearson r = 0.74, 95% CI 0.54 to 0.85; main plus branch surgeries, r = 0.79, 95% CI 0.63 to 0.89). All cause mortality aged 1 to 75 correlated with deprivation (main surgery postcode based measure, r = 0.50, 95% CI 0.22 to 0.71; main plus branch surgery based score, r = 0.55, 95% CI 0.28 to 0.74); population weighted measure, r = 0.66, 95% CI 0.43 to 0.81).
Conclusion: Practice postcode linked IMD scores provide a valid proxy for a population weighted measure in the absence of patient level data. However, by using them, the strength of association between mortality and deprivation may be underestimated
Rapid soft X-ray fluctuations in solar flares observed with the X-ray polychromator
Three flares observed by the Soft X-Ray Polychromator on the Solar Maximum Mission were studied. Flare light curves from the Flat Crystal Spectrometer and Bent Crystal Spectrometer were examined for rapid signal variations. Each flare was characterized by an initial fast (less than 1 min) burst, observed by the Hard X-Ray Burst Spectrometer (HXRBS), followed by softer gradual X-ray emission lasting several minutes. From an autocorrelation function analysis, evidence was found for quasi-periodic fluctuations with rise and decay times of 10 s in the Ca XIX and Fe XXV light curves. These variations were of small amplitude (less than 20%), often coincided with hard X-ray emissions, and were prominent during the onset of the gradual phase after the initial hard X-ray burst. It is speculated that these fluctuations were caused by repeated energy injections in a coronal loop that had already been heated and filled with dense plasma associated with the initial hard X-ray burst
Extending the Technology Acceptance Model
We extend the Technology Acceptance Model (TAM) using elements from a Task-Technology Fit Model (TTF). We test our integrated IT utilization model using path analysis. Our results provide a model with more explanatory power, which should lead to a better understanding of choices about using software
Examining Multiple Dimensions of Task Technology Fit
Investigating the fit of an information technology to a userās task, known as task-technology fit (TTF), is a frequent focus of HCI/MIS research. In such research, āfit as moderationā, one of Venkatramanās (1989) six conceptualizations of fit, is common. This conceptualization assumes two variables, e.g., task and technology, and an outcome variable. Task and technology, however, have multiple dimensions that should be considered when investigating fit. We examine three methods HCI/MIS researchers have used for augmenting the fit as moderation conceptualization for multiple dimensions. We propose and test a new method involving a single PLS model capturing the multiple dimensions of fit, which is more consistent with Venkatramanās (1989) original conceptualization and statistical model for fit as moderation than those currently in the literature. Our method as compared against one method in the literature, using a separate model for each dimension, works at least as well
TEXES Observations of M Supergiants: Dynamics and Thermodynamics of Wind Acceleration
We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M
supergiants using TEXES on the IRTF. These low opacity emission lines are
resolved at R = 50, 000 and provide new diagnostics of the dynamics and
thermodynamics of the stellar wind acceleration zone. The [Fe II] lines, from
the first excited term, are sensitive to the warm plasma where energy is
deposited into the extended atmosphere to form the chromosphere and wind
outflow. These diagnostics complement previous KAO and ISO observations which
were sensitive to the cooler and more extended circumstellar envelopes. The
turbulent velocities, Vturb is about 12 to 13 km/s, observed in the [Fe II]
forbidden lines are found to be a common property of our sample, and are less
than that derived from the hotter chromospheric C II] 2325 Angstrom lines
observed in alpha Ori, where Vturb is about 17 to 19 km/s. For the first time,
we have dynamically resolved the motions of the dominant cool atmospheric
component discovered in alpha Ori from multi-wavelength radio interferometry by
Lim et al. (1998). Surprisingly, the emission centroids are quite Gaussian and
at rest with respect to the M supergiants. These constraints combined with
model calculations of the infrared emission line fluxes for alpha Ori imply
that the warm material has a low outflow velocity and is located close to the
star. We have also detected narrow [Fe I] 24.04 um emission that confirms that
Fe II is the dominant ionization state in alpha Ori's extended atmosphere.Comment: 79 pages including 10 figures and 2 appendices. Accepted by Ap
Looking for a charge asymmetry in cosmic rays
We combine the data from PAMELA and FERMI-LAT cosmic ray experiments by
introducing a simple sum rule. This allows to investigate whether the lepton
excess observed by these experiments is charge symmetric or not. We also show
how the data can be used to predict the positron fraction at energies yet to be
explored by the AMS-02 experiment.Comment: Contribution to the proceedings of DISCRETE 2010, 5 pages, 2 figure
INTEGRAL/SPI Ī³ -ray line spectroscopy : Response and background characteristics
Ā© 2018 ESO. Reproduced with permission from Astronomy & Astrophysics. Content in the UH Research Archive is made available for personal research, educational, and non-commercial purposes only. Unless otherwise stated, all content is protected by copyright, and in the absence of an open license, permissions for further re-use should be sought from the publisher, the author, or other copyright holder.Context. The space based Ī³-ray observatory INTEGRAL of the European Space Agency (ESA) includes the spectrometer instrument "SPI". This is a coded mask telescope featuring a 19-element Germanium detector array for high-resolution Ī³-ray spectroscopy, encapsulated in a scintillation detector assembly that provides a veto for background from charged particles. In space, cosmic rays irradiate spacecraft and instruments, which, in spite of the vetoing detectors, results in a large instrumental background from activation of those materials, and leads to deterioration of the charge collection properties of the Ge detectors.Aim. We aim to determine the measurement characteristics of our detectors and their evolution with time, that is, their spectral response and instrumental background. These incur systematic variations in the SPI signal from celestial photons, hence their determination from a broad empirical database enables a reduction of underlying systematics in data analysis. For this, we explore compromises balancing temporal and spectral resolution within statistical limitations. Our goal is to enable modelling of background applicable to spectroscopic studies of the sky, accounting separately for changes of the spectral response and of instrumental background.Methods. We use 13.5 years of INTEGRAL/SPI data, which consist of spectra for each detector and for each pointing of the satellite. Spectral fits to each such spectrum, with independent but coherent treatment of continuum and line backgrounds, provides us with details about separated background components. From the strongest background lines, we first determine how the spectral response changes with time. Applying symmetry and long-term stability tests, we eliminate degeneracies and reduce statistical fluctuations of background parameters, with the aim of providing a self-consistent description of the spectral response for each individual detector. Accounting for this, we then determine how the instrumental background components change in intensities and other characteristics, most-importantly their relative distribution among detectors.Results. Spectral resolution of Ge detectors in space degrades with time, up to 15% within half a year, consistently for all detectors, and across the SPI energy range. Semi-annual annealing operations recover these losses, yet there is a small long-term degradation. The intensity of instrumental background varies anti-correlated to solar activity, in general. There are significant differences among different lines and with respect to continuum. Background lines are found to have a characteristic, well-defined and long-term consistent intensity ratio among detectors. We use this to categorise lines in groups of similar behaviour. The dataset of spectral-response and background parameters as fitted across the INTEGRAL mission allows studies of SPI spectral response and background behaviour in a broad perspective, and efficiently supports precision modelling of instrumental background.Peer reviewedFinal Published versio
Evidence for the Galactic X-ray Bulge II
A mosaic of 5 \ros~PSPC pointed observations in the Galactic plane
() reveals X-ray shadows in the keV band cast by
distant molecular clouds. The observed on-cloud and off-cloud X-ray fluxes
indicate that % and % of the diffuse X-ray background in this
direction in the \tq~keV and 1.5 keV bands, respectively, originates behind the
molecular gas which is located at 3 kpc from the Sun. The implication of
the derived background X-ray flux beyond the absorbing molecular cloud is
consistent with, and lends further support to recent observations of a Galactic
X-ray bulge.Comment: 19 pages, 5 figures, 2 table
Density Matrix Renormalization Group Study of the Spin 1/2 Heisenberg Ladder with Antiferromagnetic Legs and Ferromagnetic Rungs
The ground state and low lying excitation of the spin 1/2 Heisenberg ladder
with antiferromagnetic leg () and ferromagnetic rung () interaction is studied by means of the density matrix renormalization
group method. It is found that the state remains in the Haldane phase even for
small suggesting the continuous transition to the gapless
phase at . The critical behavior for small is studied by
the finite size scaling analysis. The result is consistent with the recent
field theoretical prediction.Comment: 11 pages, revtex, figures upon reques
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