942 research outputs found

    Fast atom diffraction inside a molecular beam epitaxy chamber, a rich combination

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    Two aspects of the contribution of grazing incidence fast atom diffraction (GIFAD) to molecular beam epitaxy (MBE) are reviewed here: the ability of GIFAD to provide \emph{in-situ} a precise description of the atomic-scale surface topology, and its ability to follow larger-scale changes in surface roughness during layer-by-layer growth. Recent experimental and theoretical results obtained for the He atom beam incident along the highly corrugated [11ˉ0][ 1\bar{1}0 ] direction of the β2\beta_{2}(2×\times4) reconstructed GaAs(001) surface are summarized and complemented by the measurements and calculations for the beam incidence along the weakly corrugated [010] direction where a periodicity twice smaller as expected is observed. The combination of the experiment, quantum scattering matrix calculations, and semiclassical analysis allows in this case to reveal structural characteristics of the surface. For the in situ measurements of GIFAD during molecular beam epitaxy of GaAs on GaAs surface we analyse the change in elastic and inelastic contributions in the scattered beam, and the variation of the diffraction pattern in polar angle scattering. This analysis outlines the robustness, the simplicity and the richness of the GIFAD as a technique to monitor the layer-by-layer epitaxial growth

    Lesson Learned from Collecting Quantified Self Information via Mobile and Wearable Devices

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    The ubiquity and affordability of mobile and wearable devices has enabled us to continually and digitally record our daily life activities. Consequently, we are seeing the growth of data collection experiments in several scientific disciplines. Although these have yielded promising results, mobile and wearable data collection experiments are often restricted to a specific configuration that has been designed for a unique study goal. These approaches do not address all the real-world challenges of “continuous data collection” systems. As a result, there have been few discussions or reports about such issues that are faced when “implementing these platforms” in a practical situation. To address this, we have summarized our technical and user-centric findings from three lifelogging and Quantified Self data collection studies, which we have conducted in real-world settings, for both smartphones and smartwatches. In addition to (i) privacy and (ii) battery related issues; based on our findings we recommend further works to consider (iii) implementing multivariate reflection of the data; (iv) resolving the uncertainty and data loss; and (v) consider to minimize the manual intervention required by users. These findings have provided insights that can be used as a guideline for further Quantified Self or lifelogging studies

    Entropic corrections to Newton's law

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    In this short letter we calculate separately the generalized uncertainty principle (GUP) and self gravitational corrections to the Newton's gravitational formula. We show that for a complete description of the GUP and self-gravity effects, both temperature and the entropy must be modified.Comment: 4 pages, Accepted for publication in "Physica Scripta",Title changed, Major revisio

    p-Wave holographic superconductors with Weyl corrections

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    We study the (3+1) dimensional p-wave holographic superconductors with Weyl corrections both numerically and analytically. We describe numerically the behavior of critical temperature TcT_{c} with respect to charge density ρ\rho in a limited range of Weyl coupling parameter γ\gamma and we find in general the condensation becomes harder with the increase of parameter γ\gamma. In strong coupling limit of Yang-Mills theory, we show that the minimum value of TcT_{c} obtained from analytical approach is in good agreement with the numerical results, and finally show how we got remarkably a similar result in the critical exponent 1/2 of the chemical potential μ\mu and the order parameter with the numerical curves of superconductors.Comment: 7 pages, 1 figure, 1 table. One refrence added, presentations improve

    Effect of pioglitazone on decreasing of proteinuria in type 2 diabetic patients with nephropathy

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    Introduction: Diabetic nephropathy that means albuminuria greater than 30 mg/day, affects about one third of diabetic patients. There are many studies about the effect of different medications for diabetic nephropathy with controversy in their results. So, the aim of the study was to investigate the effect of pioglitazone on decreasing of proteinuria in type II diabetic patients and nephropathy. Methods and materials: It is a double blind clinical trial. At first, 2356 medical carts of the patients were evaluated and 76 patients with type 2 diabetes mellitus with proteinuria greater than 250 mg / day were enrolled in 2 equal groups. In the case group, pioglitazone 15 mg/day was prescribed and patients in the control group received placebo for two months. At the beginning of the study and after 2 months, urinary protein during 24 h was measured in all of the patients and data were entered to SPSS (version23) and evaluated by using Chi- square, Mc Nemar, paired t-test and logistic regression model. Results: At the beginning of the study, urine protein during 24 h in the case and control groups were 957.7 ± 385.1 and 972.1 ± 378.6 respectively (P =.872). So, after 2 months the mean proteinuria in the case and control groups were 647.3 ± 367.2 and 896 ± 372.4 respectively that is valuable (P = 0.005). Pioglitazone had the considerable effect on FBS,HbA1c and blood triglyceride too. Conclusion: The study showed that low dose of pioglitazone is an effective, safe and inexpensive method in reducing of proteinuria in type2 diabetic patients with nephropathy

    Stochastic Analysis of Tsunami Hazard of the 1945 Makran Subduction Zone Mw 8.1–8.3 Earthquakes

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    © 2020 by the authors. Historical records of major earthquakes in the northwestern Indian Ocean along the Makran Subduction Zone (MSZ) indicate high potential tsunami hazards for coastal regions of Pakistan, Iran, Oman, and western India. There are fast-growing and populous cities and ports that are economically important, such as Chabahar (Iran), Gwadar (Pakistan), Muscat (Oman), and Mumbai (India). In this study, we assess the tsunami hazard of the 1945 MSZ event (fatalities ≈300 people) using stochastic earthquake rupture models of Mw 8.1–8.3 by considering uncertainties related to rupture geometry and slip heterogeneity. To quantify the uncertainty of earthquake source characteristics in tsunami hazard analysis, 1000 stochastic tsunami scenarios are generated via a stochastic source modeling approach. There are main objectives of this study: (1) developing stochastic earthquake slip models for the MSZ, (2) comparing results of the simulation with the existing observations of the 1945 event, and (3) evaluating the effect of uncertain fault geometry and earthquake slip based on simulated near-shore wave profiles. The 1945 Makran earthquake is focused upon by comparing model predictions with existing observations, consisting of far-field tsunami waveforms recorded on tide gauges in Karachi and Mumbai and coseismic deformation along the Pakistani coast. The results identify the source model that matches the existing observations of the 1945 Makran event best among the stochastic sources. The length, width, mean slip, and maximum slip of the identified source model are 270 km, 130 km, 2.9 m, and 19.3 m, respectively. Moreover, the sensitivity of the maximum tsunami heights along the coastline to the location of a large-slip area is highlighted. The maximum heights of the tsunami and coseismic deformation results at Ormara are in the range of 0.3–7.0 m and −2.7 to 1.1 m, respectively, for the 1000 stochastic source models.Canada Research Chair program (950-232015) ; the NSERC Discovery Grant; the Royal Society (UK) gran

    Gauss-Bonnet holographic superconductors with magnetic field

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    We study the Gauss-Bonnet (GB) holographic superconductors in the presence of an external magnetic field. We describe the phenomena away from the probe limit. We derive the critical magnetic field of the GB holographic superconductors with backreaction. Our analytical approach matches the numerical calculations. We calculate the backreaction corrections up to first order of O(κ2=8πG)O(\kappa^2=8\pi G) to the critical temperature TCT_C and the critical magnetic field BCB_C for a GB superconductor. We show that the GB coupling α\alpha makes the condensation weaker but the backreaction corrections O(κ2)O(\kappa^2) make the critical magnetic field stronger.Comment: 9 pages, 4 figures. Accepted for publication by EP

    Simulating Supersonic Turbulence in Magnetized Molecular Clouds

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    We present results of large-scale three-dimensional simulations of weakly magnetized supersonic turbulence at grid resolutions up to 1024^3 cells. Our numerical experiments are carried out with the Piecewise Parabolic Method on a Local Stencil and assume an isothermal equation of state. The turbulence is driven by a large-scale isotropic solenoidal force in a periodic computational domain and fully develops in a few flow crossing times. We then evolve the flow for a number of flow crossing times and analyze various statistical properties of the saturated turbulent state. We show that the energy transfer rate in the inertial range of scales is surprisingly close to a constant, indicating that Kolmogorov's phenomenology for incompressible turbulence can be extended to magnetized supersonic flows. We also discuss numerical dissipation effects and convergence of different turbulence diagnostics as grid resolution refines from 256^3 to 1024^3 cells.Comment: 10 pages, 3 figures, to appear in the proceedings of the DOE/SciDAC 2009 conferenc
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