2,926 research outputs found
Measurement of the local density spectrum
Since there is still disagreement among the results of various groups, a measurement of the local density spectrum with a close-packed array of four scintillators, each of area 0.14 sq cm was made. Data are taken with conventional electronics, supervised by an on-line microcomputer. The data are stored on audio cassettes and analyzed with the aid of another microcomputer. Since four independent samples for each shower are available, uncertainties inherent in results from many earlier experiments can be minimized
Temperature-dependent Raman scattering of DyScO3 and GdScO3 single crystals
We report a temperature-dependent Raman scattering investigation of DyScO3
and GdScO3 single crystals from room temperature up to 1200 {\deg}C. With
increasing temperature, all modes decrease monotonously in wavenumber without
anomaly, which attests the absence of a structural phase transition. The high
temperature spectral signature and extrapolation of band positions to higher
temperatures suggest a decreasing orthorhombic distortion towards the ideal
cubic structure. Our study indicates that this orthorhombic-to-cubic phase
transition is close to or higher than the melting point of both rare-earth
scandates (\approx 2100 {\deg}C), which might exclude the possibility of the
experimental observation of such a phase transition before melting. The
temperature-dependent shift of Raman phonons is also discussed in the context
of thermal expansion
Teach Them How They Learn: Learning Styles and Information Systems Education
The rich, interdisciplinary tradition of learning styles is markedly absent in information systems-related research. The current study applies the framework of learning styles to a common educational component of many of today’s information systems curricula - object-oriented systems development - in an effort to answer the question as to whether one’s learning style, when matched with a specific complementary instructional methodology, results in increased domain-specific performance. The data collected from 196 information systems majors enrolled in object-oriented systems development courses suggest that task performances increases significantly when the instructional methodology closely mirrors the student’s learning style inclination
System and method for confining an object to a region of fluid flow having a stagnation point
A device for confining an object to a region proximate to a fluid flow stagnation point includes one or more inlets for carrying the fluid into the region, one or more outlets for carrying the fluid out of the region, and a controller, in fluidic communication with the inlets and outlets, for adjusting the motion of the fluid to produce a stagnation point in the region, thereby confining the object to the region. Applications include, for example, prolonged observation of the object, manipulation of the object, etc. The device optionally may employ a feedback control mechanism, a sensing apparatus (e.g., for imaging), and a storage medium for storing, and a computer for analyzing and manipulating, data acquired from observing the object. The invention further provides methods of using such a device and system in a number of fields, including biology, chemistry, physics, material science, and medical science
Diffusion of Innovations and the Theory of Planned Behavior in Information Systems Research: A Metaanalysis
Diffusion of Innovations and the Theory of Planned Behavior provide the foundation on which a preponderance of information systems (IS) theory and research is built. IS scholars often assume that the basic factors proffered by these theories are significant determinants of innovation adoption. However, there has yet to be a meta-analytic examination of research in the IS field to validate this assumption. Herein, we use Tornatzky and Klein’s seminal 1982 meta-analysis of innovation characteristics as the starting point for our meta-analytic examination of Diffusion of Innovations and Theory of Planned Behavior models in IS research. In order to focus our investigation on a common criterion variable, adoption propensity, we use antecedents from both models to develop a model of innovation adoption-behavior (IAB). After describing the relationships encompassed by the IAB model, we step through a bare-bones meta-analysis. Considering the data reported in fifty-eight empirical articles, we calculate the estimated true correlations with the criterion variable to be .53 for attitude toward behavior, .33 for subjective norm, .41 for perceived behavioral control, .42 for relative advantage, .43 for compatibility, -.28 for complexity, .32 for trialability, and .38 for observability. With the exception of complexity, all correlations generalize across studies
Experimental evidence of thermal fluctuations on the X-ray absorption near-edge structure at the aluminum K-edge
After a review of temperature-dependent experimental x-ray absorption
near-edge structure (XANES) and related theoretical developments, we present
the Al K-edge XANES spectra of corundum and beryl for temperature ranging from
300K to 930K. These experimental results provide a first evidence of the role
of thermal fluctuation in XANES at the Al K-edge especially in the pre-edge
region. The study is carried out by polarized XANES measurements of single
crystals. For any orientation of the sample with respect to the x-ray beam, the
pre-edge peak grows and shifts to lower energy with temperature. In addition
temperature induces modifications in the position and intensities of the main
XANES features. First-principles DFT calculations are performed for both
compounds. They show that the pre-edge peak originates from forbidden 1s to 3s
transitions induced by vibrations. Three existing theoretical models are used
to take vibrations into account in the absorption cross section calculations:
i) an average of the XANES spectra over the thermal displacements of the
absorbing atom around its equilibrium position, ii) a method based on the crude
Born-Oppenheimer approximation where only the initial state is averaged over
thermal displacements, iii) a convolution of the spectra obtained for the atoms
at the equilibrium positions with an approximate phonon spectral function. The
theoretical spectra so obtained permit to qualitatively understand the origin
of the spectral modifications induced by temperature. However the correct
treatment of thermal fluctuation in XANES spectroscopy requires more
sophisticated theoretical tools
Assessing the Performance of Recent Density Functionals for Bulk Solids
We assess the performance of recent density functionals for the
exchange-correlation energy of a nonmolecular solid, by applying accurate
calculations with the GAUSSIAN, BAND, and VASP codes to a test set of 24 solid
metals and non-metals. The functionals tested are the modified
Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol GGA), the
second-order GGA (SOGGA), and the Armiento-Mattsson 2005 (AM05) GGA. For
completeness, we also test more-standard functionals: the local density
approximation, the original PBE GGA, and the Tao-Perdew-Staroverov-Scuseria
(TPSS) meta-GGA. We find that the recent density functionals for solids reach a
high accuracy for bulk properties (lattice constant and bulk modulus). For the
cohesive energy, PBE is better than PBEsol overall, as expected, but PBEsol is
actually better for the alkali metals and alkali halides. For fair comparison
of calculated and experimental results, we consider the zero-point phonon and
finite-temperature effects ignored by many workers. We show how Gaussian basis
sets and inaccurate experimental reference data may affect the rating of the
quality of the functionals. The results show that PBEsol and AM05 perform
somewhat differently from each other for alkali metal, alkaline earth metal and
alkali halide crystals (where the maximum value of the reduced density gradient
is about 2), but perform very similarly for most of the other solids (where it
is often about 1). Our explanation for this is consistent with the importance
of exchange-correlation nonlocality in regions of core-valence overlap.Comment: 32 pages, single pdf fil
Uncovering Research Opportunities in the Medical Informatics Field: A Quantitative Content Analysis
With rapid improvements in technology, the ever-pressing need to reduce healthcare costs, and continuing legislation emphasizing medical reforms, the demand for research within the healthcare/information systems interface is growing. In this study, we ascertain the prevalent themes from the extant medical informatics literature in an effort to motivate research beyond the traditional domain of health information technology research so information systems scholars can better understand where their expertise might contribute to advancements in healthcare. We used a quantitative content analysis method to systematically explore 2,188 article texts from journals in medical informatics, medicine, and MIS published over a ten-year period. Texts were analyzed using centering resonance analysis and factor analysis and the following themes emerged from the literature: Analytics; Healthcare Operations and Standards (with sub-themes: Operations, Project Management, and Information Assurance); Knowledge Transfer/Communication (with sub-themes: Extending beyond the Organization, Internal to the Organization, and Patient-Provider); Perceptions and Managing Expectations of Information Technology; Advancements in Research; and Software as a Service. In this article, we discuss these themes in greater detail and offer directions for future research
Diminished Antioxidant Activity of High-Density Lipoprotein–Associated Proteins in Systolic Heart Failure
Background— Diminished serum arylesterase activity, catalyzed by the high-density lipoprotein–associated paraoxonase-1, is associated with heightened systemic oxidative stress and atherosclerosis risk. In the present study, we sought to determine the prognostic role of serum arylesterase activity in subjects with systolic heart failure, particularly in relation to established cardiac biomarkers. Methods and Results— We measured serum arylesterase activity in 760 subjects with impaired left ventricular systolic function (left ventricular ejection fraction \u3c50%), and prospectively followed major adverse cardiac events (including death, nonfatal myocardial infarction, and stroke) for 3 years. In our study cohort (mean age, 64±11 years; 74% men; median left ventricular ejection fraction, 35%; median creatinine clearance, 96 mg/dL), mean serum arylesterase activity (98±25 μmol/L/min/mL) was lower compared with that in healthy control subjects (mean, 115±26 μmol/L/min/mL, P\u3c0.01) but higher compared with advanced decompensated heart failure subjects (mean, 69±22 μmol/L/min/mL, P\u3c0.01). Within our cohort, there was modest correlation between serum arylesterase activity and high-density lipoprotein cholesterol (r=0.33, P\u3c0.01) as well as B-type natriuretic peptide (r=−0.23, P\u3c0.01). Lower serum arylesterase activity was a strong predictor of poorer outcomes (hazard ratio, 2.94; 95% confidence interval, 1.54, 5.62; P\u3c0.001). After adjusting for traditional risk factors, medication use, B-type natriuretic peptide, and creatinine clearance, lower serum arylesterase still conferred an increased risk of major adverse cardiac events at 3 years (hazard ratio, 2.69; 95% confidence interval, 1.37 to 5.28; P=0.004). Conclusions— In patients with systolic heart failure, decreased serum arylesterase activity, a measure of diminished antioxidant properties of high-density lipoprotein, predicts higher risk of incident long-term adverse cardiac event independent of established clinical and biochemical risk factors
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