662 research outputs found

    Kansas city cardiomyopathy questionnaire administered to hospitalized patients with heart failure

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    Background and Purpose: The psychometric properties of the Kansas City Cardiomyopathy Questionnaire (KCCQ) have been examined primarily in community-dwelling patients with heart failure (HF). The objective of this research was to examine the properties of the KCCQ administered to patients hospitalized with HF (N = 233). Methods: Confirmatory factor analysis, Cronbach's alphas, and correlations were performed to examine the scale's dimensions, reliability, and validity. Results: Confirmatory factor analysis indicated a 5-factor solution (63.6% of the variance). The Cronbach's alpha levels were greater than .70, except for the self-efficacy dimension (.60). Convergent validity was not verified between the KCCQ and several illness severity measures. Conclusions: The psychometric properties of the KCCQ may be different based on the population in which the KCCQ is administered, which may have clinical implications

    Automating the Calibration of a Neonatal Condition Monitoring System

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    Abstract. Condition monitoring of premature babies in intensive care can be carried out using a Factorial Switching Linear Dynamical System (FSLDS) [15]. A crucial part of training the FSLDS is the manual calibration stage, where an interval of normality must be identified for each baby that is monitored. In this paper we replace this manual step by using a classifier to predict whether an interval is normal or not. We show that the monitoring results obtained using automated calibration are almost as good as those using manual calibration

    An Investigation of a Mixer-Ejector Nozzle for Jet Noise Reduction

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    An experimental study is conducted assessing the performance of an ejector together with an 8:1 aspect ratio rectangular nozzle with the eventual goal of noise reduction for jet engines. Wall static pressure and Pitot probe surveys are conducted to evaluate the performance of the ejector, and sound pressure level measurements are made to assess the impact on noise radiation. It is found that addition of vortex generating tabs at the lip of the nozzle causes large increases in secondary flow entrainment. The baseline ejector (without tabs) often encounters flow resonance with accompanying tones. The tabs have the additional benefit of eliminating those tones. In most cases tried so far, pockets of high-speed fluid remain unmixed. Since jet noise scales as velocity to the eighth power, such hot spots defeat the noise reduction goal. In some cases, there is a reduction in noise amplitudes in the mid-frequency range (5-30 kHz), however, an increase occurs on the low frequency end apparently due to flow unsteadiness. This together with a high frequency noise increase caused by the tabs results in minimal reductions in the overall sound pressure level. The focus of ongoing and future efforts is to achieve sufficient mixing and desirable noise reduction while keeping the hard-ware short and lightweight

    Continuum Foreground Polarization and Na i Absorption in Type Ia SNe

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    We present a study of the continuum polarization over the 400-600 nm range of 19 SNe Ia obtained with FORS at the VLT. We separate them into those that show Na i D lines at the velocity of their hosts and those that do not. Continuum polarization of the sodium sample near maximum light displays a broad range of values, from extremely polarized cases like SN 2006X to almost unpolarized ones like SN 2011ae. The non-sodium sample shows, typically, smaller polarization values. The continuum polarization of the sodium sample in the 400-600 nm range is linear with wavelength and can be characterized by the mean polarization (Pmean). Its values span a wide range and show a linear correlation with color, color excess, and extinction in the visual band. Larger dispersion correlations were found with the equivalent width of the Na i D and Ca ii H and K lines, and also a noisy relation between Pmean and RV, the ratio of total to selective extinction. Redder SNe show stronger continuum polarization, with larger color excesses and extinctions. We also confirm that high continuum polarization is associated with small values of RV. The correlation between extinction and polarization - and polarization angles - suggest that the dominant fraction of dust polarization is imprinted in interstellar regions of the host galaxies. We show that Na i D lines from foreground matter in the SN host are usually associated with non-galactic ISM, challenging the typical assumptions in foreground interstellar polarization models

    Negatively Charged Excitons and Photoluminescence in Asymmetric Quantum Well

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    We study photoluminescence (PL) of charged excitons (XX^-) in narrow asymmetric quantum wells in high magnetic fields B. The binding of all XX^- states strongly depends on the separation δ\delta of electron and hole layers. The most sensitive is the ``bright'' singlet, whose binding energy decreases quickly with increasing δ\delta even at relatively small B. As a result, the value of B at which the singlet--triplet crossing occurs in the XX^- spectrum also depends on δ\delta and decreases from 35 T in a symmetric 10 nm GaAs well to 16 T for δ=0.5\delta=0.5 nm. Since the critical values of δ\delta at which different XX^- states unbind are surprisingly small compared to the well width, the observation of strongly bound XX^- states in an experimental PL spectrum implies virtually no layer displacement in the sample. This casts doubt on the interpretation of PL spectra of heterojunctions in terms of XX^- recombination

    Effect of stress-triaxiality on void growth in dynamic fracture of metals: a molecular dynamics study

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    The effect of stress-triaxiality on growth of a void in a three dimensional single-crystal face-centered-cubic (FCC) lattice has been studied. Molecular dynamics (MD) simulations using an embedded-atom (EAM) potential for copper have been performed at room temperature and using strain controlling with high strain rates ranging from 10^7/sec to 10^10/sec. Strain-rates of these magnitudes can be studied experimentally, e.g. using shock waves induced by laser ablation. Void growth has been simulated in three different conditions, namely uniaxial, biaxial, and triaxial expansion. The response of the system in the three cases have been compared in terms of the void growth rate, the detailed void shape evolution, and the stress-strain behavior including the development of plastic strain. Also macroscopic observables as plastic work and porosity have been computed from the atomistic level. The stress thresholds for void growth are found to be comparable with spall strength values determined by dynamic fracture experiments. The conventional macroscopic assumption that the mean plastic strain results from the growth of the void is validated. The evolution of the system in the uniaxial case is found to exhibit four different regimes: elastic expansion; plastic yielding, when the mean stress is nearly constant, but the stress-triaxiality increases rapidly together with exponential growth of the void; saturation of the stress-triaxiality; and finally the failure.Comment: 35 figures, which are small (and blurry) due to the space limitations; submitted (with original figures) to Physical Review B. Final versio

    Spalling uniaxial strength of Al2O3 at high strain rates

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    In this article research into the uniaxial tensile strength of Al2O3 monolithic ceramic is presented. The experimental procedure of the spalling of long bars is investigated from different approaches. This method is used to obtain the tensile strength at high strain rates under uniaxial conditions. Different methodologies proposed by several authors are used to obtain the tensile strength. The hypotheses needed for the experimental set-up are also checked, and the requirements of the set-up and the variables are also studied by means of numerical simulations. The research shows that the shape of the projectile is crucial to achieve successfully tests results. An experimental campaign has been carried out including high speed video and a digital image correlation system to obtain the tensile strength of alumina. Finally, a comparison of the test results provided by three different methods proposed by different authors is presented. The tensile strength obtained from the three such methods on the same specimens provides contrasting results. Mean values vary from one method to another but the trends are similar for two of the methods. The third method gives less scatter, though the mean values obtained are lower and do not follow the same trend as the other methods for the different specimens

    The Theory/Applications Balance in Management Pedagogy: Where Do We Stand?

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    Business schools are expected to be "professional" in the sense that their mission is primarily to prepare people to practice their skills in the business world. Various critics, however, claim that management professors overemphasize theory and research and neglect the practice and applications students need to transfer classroom theory to the world of practice. This study compared an earlier sample with a more recent sample of Academy of Management members concerning the relative emphasis they believed should be placed on theory and applications in management pedagogy and the techniques they used to bring applications into the classroom. Current respondents believed that more emphasis should be placed on applications than the earlier respondents. An unexpected finding, however, was that the more recent respondents reported a lower mean usage of pedagogical techniques that are appropriate for developing students' ability to apply course concepts than the previous group. Possible reasons for these incongruent findings are discussed as well as the implications for management pedagogy.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
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