21,165 research outputs found

    Community based trial of home blood pressure monitoring with nurse-led telephone support in patients with stroke or transient ischaemic attack recently discharged from hospital.

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    BACKGROUND: High blood pressure in patients with stroke increases the risk of recurrence but management in the community is often inadequate. Home blood pressure monitoring may increase patients' involvement in their care, increase compliance, and reduce the need for patients to attend their General Practitioner if blood pressure is adequately controlled. However the value of home monitoring to improve blood pressure control is unclear. In particular its use has not been evaluated in stroke patients in whom neurological and cognitive ability may present unique challenges. DESIGN: Community based randomised trial with follow up after 12 months. PARTICIPANTS: 360 patients admitted to three South London Stroke units with stroke or transient ischaemic attack within the past 9 months will be recruited from the wards or outpatients and randomly allocated into two groups. All patients will be visited by the specialist nurse at home at baseline when she will measure their blood pressure and administer a questionnaire. These procedures will be repeated at 12 months follow up by another researcher blind as to whether the patient is in intervention or control group. INTERVENTION: INTERVENTION patients will be given a validated home blood pressure monitor and support from the specialist nurse. Control patients will continue with usual care (blood pressure monitoring by their practice). Main outcome measures in both groups after 12 months: 1. Change in systolic blood pressure.2. Cost effectiveness: Incremental cost of the intervention to the National Health Service and incremental cost per quality adjusted life year gained

    Double-active-layer index-guided InGaAsP-InP laser diode

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    A buried crescent InGaAsP-InP laser with two active layers was fabricated to study the temperature behavior of the double-carrier-confinement structure. An anomalously high characteristic temperature T0 was measured, and optical switching behavior was observed. A mode analysis and numerical calculation using a rate equation approach explained qualitatively very well the experimental results. It was revealed that both the Auger recombination in this special double-active-layer configuration and the temperature-dependent leakage current, which leads to uniform carrier distribution in both active regions, are essential to increase T0

    Does Choice Mean Freedom And Well-Being?

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    Americans live in a political, social, and historical context that values personal freedom and choice above all else, an emphasis that has been amplified by contemporary psychology. However, this article reviews research that shows that in non-Western cultures and among working-class Westerners, freedom and choice do not have the meaning or importance they do for the university-educated people who have been the subjects of almost all research on this topic. We cannot assume that choice, as understood by educated, affluent Westerners, is a universal aspiration. The meaning and significance of choice are cultural constructions. Moreover, even when choice can foster freedom, empowerment, and independence, it is not an unalloyed good. Too much choice can produce a paralyzing uncertainty, depression, and selfishness. In the United States, the path to well-being may require that we strike a balance between the positive and negative consequences of proliferating choice in every domain of life

    Regularization independent of the noise level: an analysis of quasi-optimality

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    The quasi-optimality criterion chooses the regularization parameter in inverse problems without taking into account the noise level. This rule works remarkably well in practice, although Bakushinskii has shown that there are always counterexamples with very poor performance. We propose an average case analysis of quasi-optimality for spectral cut-off estimators and we prove that the quasi-optimality criterion determines estimators which are rate-optimal {\em on average}. Its practical performance is illustrated with a calibration problem from mathematical finance.Comment: 18 pages, 3 figure

    Fractional derivatives of random walks: Time series with long-time memory

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    We review statistical properties of models generated by the application of a (positive and negative order) fractional derivative operator to a standard random walk and show that the resulting stochastic walks display slowly-decaying autocorrelation functions. The relation between these correlated walks and the well-known fractionally integrated autoregressive (FIGARCH) models, commonly used in econometric studies, is discussed. The application of correlated random walks to simulate empirical financial times series is considered and compared with the predictions from FIGARCH and the simpler FIARCH processes. A comparison with empirical data is performed.Comment: 10 pages, 14 figure

    Driven Spin Systems as Quantum Thermodynamic Machines: Fundamental Limits

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    We show that coupled two level systems like qubits studied in quantum information can be used as a thermodynamic machine. At least three qubits or spins are necessary and arranged in a chain. The system is interfaced between two split baths and the working spin in the middle is externally driven. The machine performs Carnot-type cycles and is able to work as heat pump or engine depending on the temperature difference of the baths ΔT\Delta T and the energy differences in the spin system ΔE\Delta E. It can be shown that the efficiency is a function of ΔT\Delta T and ΔE\Delta E.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.

    Construction of an isotropic cellular automaton for a reaction-diffusion equation by means of a random walk

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    We propose a new method to construct an isotropic cellular automaton corresponding to a reaction-diffusion equation. The method consists of replacing the diffusion term and the reaction term of the reaction-diffusion equation with a random walk of microscopic particles and a discrete vector field which defines the time evolution of the particles. The cellular automaton thus obtained can retain isotropy and therefore reproduces the patterns found in the numerical solutions of the reaction-diffusion equation. As a specific example, we apply the method to the Belousov-Zhabotinsky reaction in excitable media

    A Comparison of the Relationship between Obesity and Earnings in the U.S. and Germany

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    This paper investigates and compares the relationship between obesity and earnings in the U.S. and Germany. Using data from the Panel Study of Income Dynamics (U.S.) and the German Socio-Economic Panel, instrumental variables models are estimated that account for the endogeneity of body weight. We find that, in both countries, heavier women tend to earn less. For example, obesity is associated with almost 20 percent lower earnings for U.S. and German women. We test for causality using IV models; these models suggest that weight may lower labor earnings for U.S. women. However, our IV results yield no evidence of a causal impact of weight on earnings for women in Germany or for men in either country

    Alkaloids from the Sponge Stylissa carteri Present Prospective Scaffolds for the Inhibition of Human Immunodeficiency Virus 1 (HIV-1).

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    The sponge Stylissa carteri is known to produce a number of secondary metabolites displaying anti-fouling, anti-inflammatory, and anti-cancer activity. However, the anti-viral potential of metabolites produced by S. carteri has not been extensively explored. In this study, an S. carteri extract was HPLC fractionated and a cell based assay was used to evaluate the effects of HPLC fractions on parameters of Human Immunodeficiency Virus (HIV-1) infection and cell viability. Candidate HIV-1 inhibitory fractions were then analyzed for the presence of potential HIV-1 inhibitory compounds by mass spectrometry, leading to the identification of three previously characterized compounds, i.e., debromohymenialdisine (DBH), hymenialdisine (HD), and oroidin. Commercially available purified versions of these molecules were re-tested to assess their antiviral potential in greater detail. Specifically, DBH and HD exhibit a 30%-40% inhibition of HIV-1 at 3.1 μM and 13 μM, respectively; however, both exhibited cytotoxicity. Conversely, oroidin displayed a 50% inhibition of viral replication at 50 μM with no associated toxicity. Additional experimentation using a biochemical assay revealed that oroidin inhibited the activity of the HIV-1 Reverse Transcriptase up to 90% at 25 μM. Taken together, the chemical search space was narrowed and previously isolated compounds with an unexplored anti-viral potential were found. Our results support exploration of marine natural products for anti-viral drug discovery

    Finite-Size Scaling Studies of Reaction-Diffusion Systems Part III: Numerical Methods

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    The scaling exponent and scaling function for the 1D single species coagulation model (A+AA)(A+A\rightarrow A) are shown to be universal, i.e. they are not influenced by the value of the coagulation rate. They are independent of the initial conditions as well. Two different numerical methods are used to compute the scaling properties: Monte Carlo simulations and extrapolations of exact finite lattice data. These methods are tested in a case where analytical results are available. It is shown that Monte Carlo simulations can be used to compute even the correction terms. To obtain reliable results from finite-size extrapolations exact numerical data for lattices up to ten sites are sufficient.Comment: 19 pages, LaTeX, 5 figures uuencoded, BONN HE-94-0
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