Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells

A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.Comment: 5 figure

Endogenous driving and synchronization in cardiac and uterine virtual tissues: bifurcations and local coupling

Cardiac and uterine muscle cells and tissue can be either autorhythmic or excitable. These behaviours exchange stability at bifurcations produced by changes in parameters, which if spatially localized can produce an ectopic pacemaking focus. The effects of these parameters on cell dynamics have been identified and quantified using continuation algorithms and by numerical solutions of virtual cells. The ability of a compact pacemaker to drive the surrounding excitable tissues depends on both the size of the pacemaker and the strength of electrotonic coupling between cells within, between, and outside the pacemaking region. We investigate an ectopic pacemaker surrounded by normal excitable tissue. Cell–cell coupling is simulated by the diffusion coefficient for voltage. For uniformly coupled tissues, the behaviour of the hybrid tissue can take one of the three forms: (i) the surrounding tissue electrotonically suppresses the pacemaker; (ii) depressed rate oscillatory activity in the pacemaker but no propagation; and (iii) pacemaker driving propagations into the excitable region. However, real tissues are heterogeneous with spatial changes in cell–cell coupling. In the gravid uterus during early pregnancy, cells are weakly coupled, with the cell–cell coupling increasing during late pregnancy, allowing synchronous contractions during labour. These effects are investigated for a caricature uterine tissue by allowing both excitability and diffusion coefficient to vary stochastically with space, and for cardiac tissues by spatial gradients in the diffusion coefficient

Sleep quality, mental health and body mass index among undergraduate medical students: a cross-sectional study

Background: Association of sleep disorders is found cardiovascular mortality, stroke, diabetes, impaired glucose tolerance, immune dysfunction, endocrine impairments, and psychiatric morbidities including depression. Sleep quality affects college students physical and psychological health. Thus, poor sleep quality is a serious problem in college students. This study was done to assess the quality of sleep among undergraduate medical college students, to explore relationship between quality of sleep and body mass index, to study relationship between quality of sleep and anxiety, to study relationship between quality of sleep and depression.Methods: Total 300 medical students were selected by systematic random sampling method i.e. 25 students from each year studying in 3 government medical college were selected. A descriptive questionnaire for all socio-demographic parameters along with validated instrument i.e. for sleep quality, Pittsburgh sleep quality index (PSQI), for anxiety Hamilton anxiety rating scale and for depression, Becks depression inventory were used for the data collection instruments.Results: Amongst the 300 subjects 189 (63.00%) were found to be poor sleepers. The sleep quality was poor among the subjects who are in final academic year though the difference was not statistically significant (c²=2.78, df=3, p=0.4267). It was found that sleep quality was decreased among overweight and obese persons, but the difference was not statistically significant. (c²=4.657, df=2, p=0.0974). Prevalence of anxiety was found to be more in poor sleepers. Depression was also more common among the poor sleepers and the difference was statistically significant.Conclusions: Poor sleep quality was associated with depression and anxiety in students

Ayurveda management of Rheumatoid Arthritis - A Case Study

Rheumatoid Arthritis is an autoimmune disease that can cause joint pain and damage throughout the body. Rheumatoid Arthritis is a chronic inflammatory disorder that can affect more on joints. As per Ayurvedic science Rheumatoid Arthritis sign and symptoms resemblance with Aamvata. Aamvata is the disease caused by impairment of Agni, formation of Ama and vitiation of Vatadosha. There is limited treatment in modern science for rheumatoid arthritis. Ayurveda treatment has the best result for Amavata. So in this case study Ayurveda treatment has used to cure Aamvata

Camera Shake Removal With Multiple Images Via Weighted Fourier Burst Accumulation

Blur introduced in an image from camera shake is mostly due to the 3D rotation of the camera. This results in a blur kernel which is non uniform throughout the image. Hence each image in the burst is blurred differently. Various experiments were done to find the deblurred image either with single image or with multiple image. In this paper we analyze multiple image approaches, which capture and combine multiple frames in order to make deblurring more robust and tractable. If the photographer takes many images known as burst, we show that a clear and sharp image can be obtained by combining these multiple images. Also for this work the blurring kernel is unknown (blind) and also it is not found. The methodology used here is Fourier Burst Accumulation which performs a weighted average in Fourier Domain where the weights depend on Fourier spectrum magnitude. In simple words the method can be generalized as Align and Average procedure. Experiments with real camera data and extensive comparisons, show that the proposed burst accumulation algorithm achieves results faster

An open source MATLAB package to perform basic statistical analysis of turbulence data and other complex systems along with its application to Fokker-Planck equation and Integral fluctuation theorem

We present a user-friendly open-source \proglang{MATLAB\textsuperscript{\textregistered}} package developed by the research group Turbulence, Wind energy and Stochastics (TWiSt) at the Carl von Ossietzky University of Oldenburg. This package enables to perform a standard analysis of given turbulent data and extracts the stochastic equations describing the scale-dependent cascade process in turbulent flows through Fokker-Planck equations. As a precondition, Markovian properties of the process in scale are tested. Such a stochastic scale-dependent cascade process allows a comprehensive statistical description in terms of the complexity of the data. Cascade trajectories can be defined as single events, for each of which a total entropy production can be determined. For such entropy fluctuations a rigorous law of non-equilibrium stochastic thermodynamics, namely the integral fluctuation theorem, will be verified. As the analysis of the scale-dependent cascade process through a hierarchy of spatial and temporal scales in turbulent flows is an integral part of turbulence theory, this interdisciplinary treatment of the turbulent cascade process has the potential for a new way to link the statistical description of turbulence (via common two-point increment statistics), non-equilibrium stochastic thermodynamics and local turbulent flow structures. The presented package can be used also for the analysis of other data with turbulent like complexity.Comment: This open source MATLAB package can be downloaded with all the supplementary material (data, source code and standalone applications (64-bit) for Windows, macOS and Linux) to replicate all the results presented in this paper from the repository on GitHub https://github.com/andre-fuchs-uni-oldenburg/OPEN_FPE_IF

Brillouin-zone Unfolding of Perfect Supercells Having Nonequivalent Primitive Cells Illustrated with a Si/Ge Tight-Binding parameterization

Numerical calculations of nanostructure electronic properties are often based on a nonprimitive rectangular unit cell, because the rectangular geometry allows for both highly efficient algorithms and ease of debugging while having no drawback in calculating quantum dot energy levels or the one-dimensional energy bands of nanowires. Since general nanostructure programs can also handle superlattices, it is natural to apply them to these structures as well, but here problems arise due to the fact that the rectangular unit cell is generally not the primitive cell of the superlattice, so that the resulting E(k) relations must be unfolded to obtain the primitive- cell E(k) curves. If all of the primitive cells in the rectangular unit cell are identical, then the unfolding is reasonably straightforward; if not, the problem becomes more difficult. Here, we provide a method for zone unfolding when the primitive cells in a rectangular cell are not all identical. The method is applied to a Si(4)Ge(4) superlattice using a set of optimized Si and Ge tight-binding strain parameters

Role of Fiber Orientation in Atrial Arrythmogenesis

Electrical wave-front propagation in the atria is determined largely by local fiber orientation. Recent study suggests that atrial fibrillation (AF) progresses with enhanced anisotropy. In this work, a 3D rabbit atrial anatomical model at 20 × 20 × 20 μm3 resolution with realistic fiber orientation was constructed based on the novel contrast-enhanced micro-CT imaging. The Fenton-Karma cellular activation model was adapted to reproduce rabbit atrial action potential period of 80 ms. Diffusivities were estimated for longitudinal and transverse directions of the fiber orientation respectively. Pacing was conducted in the 3D anisotropic atrial model with a reducing S2 interval to facilitate initiation of atrial arrhythmia. Multiple simulations were conducted with varying values of diffusion anisotropy and stimulus locations to evaluate the role of anisotropy in initiating AF. Under physiological anisotropy conditions, a rapid right atrial activation was followed by the left atrial activation. Excitation waves reached the atrio-ventricular border where they terminated. Upon reduction of conduction heterogeneity, re-entry was initiated by the rapid pacing and the activation of both atrial chambers was almost simultaneous. Myofiber orientation is an effective mechanism for regulating atrial activation. Modification of myoarchitecture is proarrhythmic