56,205 research outputs found
Adult-onset primary immunodeficiencies
No full textDifferent individuals with the same kind of primary immunodeficiency may start having symptoms from early childhood on, or alternatively much later in adult life, or never. The differences in phenotype can only partly be deduced from genotype-analysis or—in case of female patients with X-linked diseases—from age-related skewing of lyonisation. The role of compensatory immune mechanisms is less clear. The microbial spectrum of infections is usually the same for both adult and infantile forms of a special primary immunodeficiency syndrome. Yet, many of the adult forms are associated with non-infectious complications, such as granuloma formation, autoimmunity or tumors. Besides standard antibiotic treatment and IgG replacement therapy, there are now different cytokine- or enzyme-replacement regimens available for some of the primary immunodeficiencies. However, exact diagnostic classification of the immunodeficiency should be obtained before such treatment modalities are used. Adult primary immunodeficiency syndromes therefore represent a challenge to both clinicians and molecular biologists.Primäre Defekte des Immunsystems können sich bei verschiedenen Individuen entweder in früher Kindheit, spät im Erwachsenenalter oder auch nie manifestieren. Die verschiedenen Phänotypen können teilweise durch die Genotypanalyse oder—bei weiblichen Patienten und X-chromosomalem Erbgang—durch die altersabhängige Verschiebung der Lyonisation erklärt werden. Eine wichtige Rolle spielen wahrscheinlich auch kompensatorische Immunmechanismen. Das Erregerspektrum eines adulten primären Immundefektsyndroms stimmt im Wesentlichen mit demjenigen der juvenilen Form überein. Nicht selten stehen bei den adulten Formen klinisch nicht die Infektkomplikationen, sondern assoziierte Phänomene wie Granulombildung, Autoimmunität oder Neoplasie im Vordergrund. Neben einer adäquaten, erregerspezifischen Antibiose stehen heute für einige primäre Immundefizienzen spezifische Substitutionstherapien in Form von humanem Immunglobulin G Präparationen, rekombinanten Zytokinen oder Enzymen zur Verfügung. Der Einsatz dieser Therapieformen bedingt allerdings eine genaue diagnostische Klassifikation des immunologischen Defekts. Adulte primäre Immundefektsyndrome stellen daher eine Herausforderung für den Kliniker und für den Molekularbiologen dar.<br/
Comparison of the level of simple, and complex reaction time during non-specific and specific stimuli in a selected sport.
No full textAutor: Matěj Salzer Název: Porovnání úrovně jednoduché, a složité reakční doby při nespecifických a specifických podnětech ve vybraném sportovním odvětví Cíl: Hlavním cílem této práce je zjistit a porovnat reakční dobu jednotlivých výkonnostních úrovní v šermu kordem a reakční doby mezi ženami a muži. Dále porovnání reakční doby obecné a specifické. Metody: Byla zjišťována reakční doba na vizuální podmět pomocí zařízení fittronic: Fitroreaction, Fitro tapping a terče Favero. Nestandartními testy. Výzkumný soubor je tvořen 28 účastníky, z toho 18 mužů a 10 žen. Skupiny jsou rozděleny následujícím způsobem: reprezentaci, výkonnostní a rekreační. Skupiny jsou rozděleny podle výkonnosti na žebříčku Českého šermířského svazu. Výsledky: Byl zjištěn statisticky významný rozdíl mezi reprezentační a rekreační skupinou, a to u všech měřených hodnot v hodnotě p= <,001. S nejnižším rozdílem v průměru 54,0 ms a nejvyšším rozdílem průměrů 81,5 ms. Ale u skupiny reprezentační a výkonnostní rozdíl v reakčních dobách nalezen nebyl Dále nebyl zjištěn rozdíl Statisticky významný rozdíl mezi reakcí žen a mužů, kromě u jednoduché obecné reakce u rekreační skupiny. Naposled byl zjištěn statistický rozdíl mezi obecnou a specifickou reakční dobou opět p= <,001. U složité reakce byla rychlejší reakce s kordem. U jednoduché...Author: Matěj Salzer Title: Comparison of the level of simple, and complex reaction time during non-specific and specific stimuli in a selected sport. Objective: The main aim of this study is to determine and compare the reaction times of different performance levels in fencing with the epee, reaction times between women and men. Furthermore, it compares general and specific reaction times. Methods: Reaction time to visual stimuli was measured using Fittronic devices: Fitroreaction, Fitro tapping, and Favero targets. The research sample consists of 28 participants, including 18 men and 10 women. The groups are divided as follows: representation, performance, and recreational. Where the groups are divided according to performance on the ladder of the Czech Fencing Association. Results: A statistically significant difference was found between the representation and recreational group, in all measured values at p = <0.001. With the lowest difference in average of 54.0 ms and the highest difference in averages of 81.5 ms. However, no difference in reaction times was found between the representation and performance group. Furthermore, no statistically significant difference was found between the reaction of women and men, except for simple general reaction in the recreational group. Lastly, a...Department of Sport GamesKatedra sportovních herFakulta tělesné výchovy a sportuFaculty of Physical Education and Spor
A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Large-eddy simulation of a separated flow with a sub-filter scale model based on the integral length-scale
No full textA new sub-filter scale model for large-eddy simulations, which uses a length-scale proportional to the integral scale of the turbulence instead of the grid resolution to parametrize the modelled stresses, will be assessed in the prediction of the flow of a boundary-layer over a rough surface, which includes separation and reattachment
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
Direct numerical simulation of turbulent Couette-Poiseuille flow with zero skin friction
No full textThe near-wall scaling of mean velocity U(y) is addressed for the case of zero skin friction on one wall of a fully turbulent channel flow. The present DNS results can be added to the evidence in support of the conjecture that U is proportional to √yw in the region just above the wall at which the mean shear dU/dy = 0
Real-space Manifestations of Bottlenecks in Turbulence Spectra
No full textAn energy-spectrum bottleneck, a bump in the turbulence spectrum between the inertial and dissipation ranges, is shown to occur in the non-turbulent, one-dimensional, hyperviscous Burgers equation and found to be the Fourier-space signature of oscillations in the real-space velocity, which are explained by boundary-layer-expansion techniques. Pseudospectral simulations are used to show that such oscillations occur in velocity correlation functions in one- and three-dimensional hyperviscous hydrodynamical equations that display genuine turbulence
Braid Entropy of Faraday Waves driven 2D Turbulence
No full textWe report new experimental results that use tools from braid theory to characterize two-dimensional turbulent flows driven by Faraday waves. The average topological length of the material fluid lines is found to grow exponentially with time. It allows us to compute the braid’s topological entropy SBraid. We show that SBraid increases as the square root of the turbulence kinetic energy E ~ u^2, where u^2 is the horizontal velocity variance . At long times, the PDFs of Lbraid are positively skewed and present strong exponential tails
Mean flow generation by Görtler Vortices in a rotating annulus with librating side walls
No full textLongitudinal libration of the cylinder side walls of a rotating annulus in the supercritical regime induces a centrifugally unstable Stokes boundary layer which generates Görtler vortices only in a portion of a libration cycle. We show for the first time that these vortices propagate into the fluid bulk and generate an azimuthal mean flow which is retrograde (prograde) over the outer (inner) cylinder side wall. Direct numerical simulations (DNS) are carried out and Reynolds-averaged equations and kinetic energy budget of mean and fluctuating flow are used as diagnostic equations to discuss the generation mechanism and scaling behavior of the azimuthal mean flow in the fluid bulk
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