3,653 research outputs found
Developing attitudes towards science measures
In this study, we describe the development of measures used to examine pupils' attitudes towards science. In particular, separate measures for attitudes towards the following areas were developed: learning science in school, practical work in science, science outside of school, importance of science, self-concept in science, and future participation in science. In developing these measures, criticisms of previous attitude studies in science education were noted. In particular, care was taken over the definition of each of the attitude constructs, and also ensuring that each of the constructs was unidimensional. Following an initial piloting process, pupils aged 11-14 from five secondary schools throughout England completed questionnaires containing the attitude measures. These questionnaires were completed twice by pupils in these schools, with a gap of four weeks between the first and second measurements. Altogether, 932 pupils completed the first questionnaire and 668 pupils completed the second one. Factor analysis carried out on the resulting data confirmed the unidimensionality of the separate attitude constructs. Also, it was found that three of the constructs - learning science in school, science outside of school, and future participation in science - loaded on one general attitude towards science factor. Further analysis showed that all the measures showed high internal reliability (Cronbach's a > 0.7). A particular strength of the approach used in this study was that it allowed for attitude measures to be built up step-by-step, therefore allowing for the future consideration of other relevant constructs
Timothy Schmidt, trumpet
This senior recital from March 31, 2003 featured Timothy Schmidt (trumpet) assisted by Susan Teicher (piano) and Richard Rossi (organ)
Design and Characterization of a Neutron Calibration Facility for the Study of sub-keV Nuclear Recoils
As part of an experimental effort to demonstrate sensitivity in a large-mass
detector to the ultra-low energy recoils expected from coherent
neutrino-nucleus elastic scattering, we have designed and built a highly
monochromatic 24 keV neutron beam at the Kansas State University Triga Mark-II
reactor. The beam characteristics were chosen so as to mimic the soft recoil
energies expected from reactor antineutrinos in a variety of targets, allowing
to understand the response of dedicated detector technologies in this yet
unexplored sub-keV recoil range. A full characterization of the beam properties
(intensity, monochromaticity, contaminations, beam profile) is presented,
together with first tests of the calibration setup using proton recoils in
organic scintillator.Comment: submitted to Nucl. Instr. Meth.
Large-N supersymmetric beta-functions
We present calculations of the leading and O(1/N) terms in a large-N
expansion of the \beta-functions for various supersymmetric theories: a
Wess-Zumino model, supersymmetric QED and a non-abelian supersymmetric gauge
theory. In all cases N is the number of a class of the chiral superfields in
the theory.Comment: 9 pages, tex, five figures. Uses harvmac and epsf. Revised to include
a discussion of higher loop DRED ambiguities. Some references added, and
notation clarifie
Two-Photon Decay Widths of Higgs Particles
Two--photon decays of Higgs bosons are important channels for the search of
these particles in the intermediate mass range at the colliders LHC and
SSC. Dynamical aspects of the Higgs coupling to two photons can also be studied
by means of the fusion of Higgs particles at high--energy
ee linear colliders. Extending earlier analyses which had been
restricted to the Standard Model, we present in this note the QCD radiative
corrections to the decay widths of scalar and pseudoscalar
Higgs particles in multi--doublet extensions of the Higgs sector, as realized
for instance in supersymmetric theories.Comment: 8pages + 3figures (not included, a hard copy is available from A.D.
upon request), Prep. DESY 92-170 (to appear in Phys. Lett. B
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Gene expression profiling of bone cells on smooth and rough titanium surfaces
Titanium (Ti) and Ti alloys are widely used as dental and orthopaedic implants, but the effects of the surface characteristics of these materials on the response of cells and target tissues is not well understood. The present study has therefore examined the effects of a rough Ti (RT) and a smooth Ti (ST) surface on human bone cells in vitro. Scanning electron microscopy showed attachment and spreading of cells on both surfaces. Expression profiling using ATLAS™ gene arrays showed marked differences in gene responses after 3 h of culture. A number of osteoblast genes were identified as "roughness response" genes on the basis of changes in expression on the RT compared with the ST surfaces. The surface roughness of Ti was thus found to have a profound effect on the profile of genes expressed by the bone cells, and suggests that improvements in the biological activity and possibly the clinical efficacy of these materials could be achieved by selective regulation of gene expression mediated by controlled modification of Ti surface
Influence of the Characteristics of the STM-tip on the Electroluminescence Spectra
We analyze the influence of the characteristics of the STM-tip (applied
voltage, tip radius) on the electroluminescence spectra from an STM-tip-induced
quantum dot taking into account the many-body effects. We find that positions
of electroluminescence peaks, attributed to the electron-hole recombination in
the quantum dot, are very sensitive to the shape and size of the confinement
potential as determined by the tip radius and the applied voltage. A critical
value of the tip radius is found, at which the luminescence peak positions as a
function of the tip radius manifest a transition from decreasing behavior for
smaller radii to increasing behavior for larger radii. We find that this
critical value of the tip radius is related to the confinement in the lateral
and normal direction.Comment: 15 pages, 5 figure
Derivation and validation of a multivariate model to predict mortality from pulmonary embolism with cancer: The POMPE-C tool
BackgroundClinical guidelines recommend risk stratification of patients with acute pulmonary embolism (PE). Active cancer increases risk of PE and worsens prognosis, but also causes incidental PE that may be discovered during cancer staging. No quantitative decision instrument has been derived specifically for patients with active cancer and PE. Methods Classification and regression technique was used to reduce 25 variables prospectively collected from 408 patients with AC and PE. Selected variables were transformed into a logistic regression model, termed POMPE-C, and compared with the pulmonary embolism severity index (PESI) score to predict the outcome variable of death within 30 days. Validation was performed in an independent sample of 182 patients with active cancer and PE. Results POMPE-C included eight predictors: body mass, heart rate > 100, respiratory rate, SaO2%, respiratory distress, altered mental status, do not resuscitate status, and unilateral limb swelling. In the derivation set, the area under the ROC curve for POMPE-C was 0.84 (95% CI: 0.82-0.87), significantly greater than PESI (0.68, 0.60-0.76). In the validation sample, POMPE-C had an AUC of 0.86 (0.78-0.93). No patient with POMPE-C estimate ≤ 5% died within 30 days (0/50, 0-7%), whereas 10/13 (77%, 46-95%) with POMPE-C estimate > 50% died within 30 days. Conclusion In patients with active cancer and PE, POMPE-C demonstrated good prognostic accuracy for 30 day mortality and better performance than PESI. If validated in a large sample, POMPE-C may provide a quantitative basis to decide treatment options for PE discovered during cancer staging and with advanced cancer
Phase stability of the AlxCrFeCoNi alloy system
The addition of Al to the A1 CrFeCoNi alloy has been shown to promote the formation of intermetallic phases, offering possibilities for the development of alloys with advantageous mechanical properties. However, despite numerous experimental investigations, there remain significant uncertainties as to the phase equilibria in this system particularly at temperatures below 1000°C. The present study makes a systematic assessment of the literature data pertaining to the equilibrium phases in alloys of the AlxCrFeCoNi system. Two alloys, with atomic ratios, x = 0.5 and 1.0, are then selected for further experimental investigation, following homogenisation (1200°C/72 h) and subsequent long-duration (1000 h) heat-treatments at 1000, 850 and 700°C. The Al0.5 alloy was found to be dual-phase A1 + B2 in the homogenised condition and following exposure at 1000°C but D8b phase precipitates developed following heat-treatment at the lower temperatures. In the Al1.0 alloy, B2, A2 and A1 phases were identified in the homogenised condition and at 1000°C. At 850 and 750°C, the A2 phase was replaced by the D8b phase. These experimental observations were used alongside literature data to assess the veracity of CALPHAD predictions made using the TCHEA4 thermodynamic database
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