81 research outputs found
Simultaneously-Measured Mid-Infrared Refractive Indices of GaAs/AlGaAs
We present our results for a simultaneous measurement of the refractive
indices of Gallium Arsenide (GaAs) and Aluminum Gallium Arsenide
(AlGaAs) in the spectral region from to
( to ). These
values are obtained from a monocrystalline thin-film multilayer Bragg mirror of
excellent purity (background doping ), grown via molecular beam epitaxy. To recover the
refractive indices over such a broad wavelength range, we fit a dispersion
model for each material. For that, we measure both a photometrically accurate
transmittance spectrum of the Bragg mirror via Fourier-transform infrared
spectrometry and the individual physical layer thicknesses of the structure via
scanning electron microscopy. To infer the uncertainty of the refractive index
values, we estimate relevant measurement uncertainties and propagate them via a
Monte-Carlo-type method. This method conclusively yields propagated relative
uncertainties on the order of over the measured spectral range for
both GaAs and AlGaAs. The fitted model can also approximate
the refractive index for MBE-grown AlGaAs for . These updated values will be essential in the design and
fabrication of next-generation active and passive optical devices in a spectral
region which is of high interest in many fields, e.g., laser design and
cavity-enhanced spectroscopy.Comment: 20 pages, 5 figures, submitted to PR
Skull of Rhinoceros sondaicus in the American Museum of Natural History
3 p. : ill. ; 24 cm.Includes bibliographical references
OpenLB User Guide: Associated with Release 1.6 of the Code
OpenLB is an object-oriented implementation of LBM. It is the first
implementation of a generic platform for LBM programming, which is shared with
the open source community (GPLv2). Since the first release in 2007, the code
has been continuously improved and extended which is documented by thirteen
releases as well as the corresponding release notes which are available on the
OpenLB website (https://www.openlb.net). The OpenLB code is written in C++ and
is used by application programmers as well as developers, with the ability to
implement custom models OpenLB supports complex data structures that allow
simulations in complex geometries and parallel execution using MPI, OpenMP and
CUDA on high-performance computers. The source code uses the concepts of
interfaces and templates, so that efficient, direct and intuitive
implementations of the LBM become possible. The efficiency and scalability has
been checked and proved by code reviews. This user manual and a source code
documentation by DoxyGen are available on the OpenLB project website
de.NBI Cloud federation through ELIXIR AAI
Belmann P, Fischer B, KrĂŒger J, et al. de.NBI Cloud federation through ELIXIR AAI. F1000Research. 2019;8: 842.The academic de.NBI Cloud offers compute resources for life science research in Germany. At the beginning of 2017, de.NBI Cloud started to implement a federated cloud consisting of five compute centers, with the aim of acting as one resource to their users. A federated cloud introduces multiple challenges, such as a central access and project management point, a unified account across all cloud sites and an interchangeable project setup across the federation. In order to implement the federation concept, de.NBI Cloud integrated with the ELIXIR authentication and authorization infrastructure system (ELIXIR AAI) and in particular Perun, the identity and access management system of ELIXIR. The integration solves the mentioned challenges and represents a backbone, connecting five compute centers which are based on OpenStack and a web portal for accessing the federation.This article explains the steps taken and software components implemented for setting up a federated cloud based on the collaboration between de.NBI Cloud and ELIXIR AAI. Furthermore, the setup and components that are described are generic and can therefore be used for other upcoming or existing federated OpenStack clouds in Europe
Myelin insulation as a risk factor for axonal degeneration in autoimmune demyelinating disease
Axonal degeneration determines the clinical outcome of multiple sclerosis and is thought to result from exposure of denuded axons to immune-mediated damage. Therefore, myelin is widely considered to be a protective structure for axons in multiple sclerosis. Myelinated axons also depend on oligodendrocytes, which provide metabolic and structural support to the axonal compartment. Given that axonal pathology in multiple sclerosis is already visible at early disease stages, before overt demyelination, we reasoned that autoimmune inflammation may disrupt oligodendroglial support mechanisms and hence primarily affect axons insulated by myelin. Here, we studied axonal pathology as a function of myelination in human multiple sclerosis and mouse models of autoimmune encephalomyelitis with genetically altered myelination. We demonstrate that myelin ensheathment itself becomes detrimental for axonal survival and increases the risk of axons degenerating in an autoimmune environment. This challenges the view of myelin as a solely protective structure and suggests that axonal dependence on oligodendroglial support can become fatal when myelin is under inflammatory attack
A second note on the geographical differentiation of Amphisbaena fuliginosa L., 1758 (Squamata, Amphisbaenidae), with a consideration of the forest refuge model of speciation
26th Annual Computational Neuroscience Meeting (CNS*2017): Part 3 - Meeting Abstracts - Antwerp, Belgium. 15â20 July 2017
This work was produced as part of the activities of FAPESP Research,\ud
Disseminations and Innovation Center for Neuromathematics (grant\ud
2013/07699-0, S. Paulo Research Foundation). NLK is supported by a\ud
FAPESP postdoctoral fellowship (grant 2016/03855-5). ACR is partially\ud
supported by a CNPq fellowship (grant 306251/2014-0)
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