1,130 research outputs found

    Theoretical and experimental assessment of the non-linear scattering functions for the cad of non-linear microwave circuits

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    The Non-Linear Scattering Functions have been theoretically defined and experimentally measured for the linear-equivalent design of non-linear circuits in arbitrary large signal conditions. Non-linear measures and simulations have been compared, with good agreement. Linear CAD concepts can therefore be extended to non-linear circuits in a rigorous way

    Start-up inertia as an origin for heterogeneous flow

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    For quite some time non-monotonic flow curve was thought to be a requirement for shear banded flows in complex fluids. Thus, in simple yield stress fluids shear banding was considered to be absent. Recent spatially resolved rheological experiments have found simple yield stress fluids to exhibit shear banded flow profiles. One proposed mechanism for the initiation of such transient shear banding process has been a small stress heterogeneity rising from the experimental device geometry. Here, using Computational Fluid Dynamics methods, we show that transient shear banding can be initialized even under homogeneous stress conditions by the fluid start-up inertia, and that such mechanism indeed is present in realistic experimental conditions

    RF and IF mixer optimum matching impedances extracted by large-signal vectorial measurements

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    This paper introduces a new technique that allows us to measure the admittance conversion matrix of a two-port device,using a Nonlinear Vector Network Analyzer.This method is applied to extract the conversion matrix of a 0.2 µµµµm pHEMT,driven by a 4.8 GHz pump signal,at different power levels,using an intermediate frequency of 600 MHz.The issue on data inconsistency due to phase randomization among different measurements is discussed and a proper pre- processing algorithm is proposed to fix the problem. The output of this work consists of a comprehensive experimental evaluation of up-and down-conversion maximum gain,stability,and optimal RF and IF impedances

    Late Palaeozoic to Neogene Geodynamic Evolution of the north-eastern Oman Margin.

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    When the highlands of Arabia were still covered with an ice shield in the latest Carboniferous/Early Permian period, separation of Gondwana started. This led to the creation of the Batain basin (part of the early Indian Ocean), off the northeastern margin of Oman. The rifting reactivated an Infra-Cambrian rift shoulder along the northeastern Oman margin and detritus from this high was shed into the interior Oman basin. Whereas carbonate platform deposits became widespread along the margin of the Neo-Tethys (northern rim of Oman), drifting and oceanization of the Batain basin started only in Late Jurassic/Early Cretaceous time. Extensional tectonics was followed in the Late Cretaceous by contraction caused by the northward drift of Greater India and Afro-Arabia. This resulted in the collision of Afro-Arabia with an intra-oceanic trench and obduction of the Semail ophiolite and the Hawasina nappes south to southwestward onto the northern Oman margin ~80 m.y. ago. During the middle Cretaceous, the oceanic lithosphere (including the future eastern ophiolites of Oman) drifted northwards as part of the Indian plate. At the Cretaceous-Palaeogene transition (~65 Ma), oblique convergence between Greater India and Afro-Arabia caused fragments of the early Indian Ocean to be thrust onto the Batain basin. Subsequently, the Lower Permian to uppermost Maastrichtian sediments and volcanic rocks of the Batain basin, along with fragments of Indian Ocean floor (eastern ophiolites), were obducted northwestward onto the northeastern margin of Oman. Palaeogene neo-autochtonous sedimentary rocks subsequently covered the nappe pile. Tertiary extensional tectonics related to Red Sea rifting in the Late Eocene was followed by Miocene shortening, associated with the collision of Arabia and Eurasia and the formation of the Oman Mountains

    Microwave small-signal modelling of FinFETs using multi-parameter rational fitting method

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    An effective approach based on a multi-parameter rational fitting technique is proposed to model the microwave small-signal response of active solid-state devices. The model is identified by fitting multibias scattering-parameter measurements and its analytical expression is implemented in a commercial microwave circuit simulator. The approach has been applied to the modelling of a silicon-based FinFET, and an excellent agreement is obtained between the measured data and model predictions

    Opening the black box of selection

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    Effect of Three Legumes Containing Different Condensed Tannin Concentrations on the in Vitro Formation of the Pastoral Flavour Compound; Skatole

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    Feeding legumes, such as white clover (Trifolium repens), results in higher intakes and increased animal production compared to grasses (Ulyatt, 1981). Skatole is produced in the rumen from plant protein fermentation and is associated with undesirable pastoral flavours in meat (Young et al. 2002). Feeding white clover causes a greater skatole concentration in the rumen compared to perennial ryegrass (Lolium perenne) or Lotus corniculatus, as the protein in white clover is highly soluble and rapidly degraded (Schreurs et al., 2004). The condensed tannins (CT) in Lotus species slow protein degradation in the rumen (Aerts et al., 1999). The aim of this study was to determine the effect of legumes with different concentrations of CT on skatole formation

    Selection into medicine : the predictive validity of an outcome-based procedure

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    Acknowledgements: The authors would like to thank Dr. Kelly Dore for valuable advice and sharing Computer-based Assessment for Sampling Personal characteristics (CASPer) assignments in order to develop our Situational Judgement Test and Angela Verheyen and Guus Smeets for their essential support in gathering data.Peer reviewedPublisher PD

    Rituximab administration in third trimester of pregnancy suppresses neonatal B-cell development

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    We describe the effect on the neonate of administration of rituximab to a woman with idiopathic thrombocytopenic purpura (ITP). Rituximab, an anti-CD20 antibody, was given weekly for 4 weeks to a woman with ITP in her third trimester of pregnancy. One month after the last rituximab administration a healthy girl was born. She had normal growth and development during the first six months. At birth, B-lymphocytes were not detectable. Rituximab levels in mother and neonate were 24000 and 6700 ng/mL, respectively. Only 7 cases of rituximab administration during pregnancy were described. No adverse events are described for fetus and neonate. We demonstrate that rituximab passes the placenta and inhibits neonatal B-lymphocyte development. However, after 6 months B-lymphocyte levels normalized and vaccination titres after 10 months were adequate. No infection-related complications occurred. Rituximab administration during pregnancy appears to be safe for the child but further studies are warranted. Copyright © 2008 D. T. Klink et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1

    Dietary Cholesterol Concentration and Duration Degrade Long-Term Memory of Classical Conditioning of the Rabbit's Nictitating Membrane Response

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    A rabbit model of Alzheimer's disease based on feeding a cholesterol diet for eight weeks shows sixteen hallmarks of the disease, including learning and memory changes. Although we have shown 2% cholesterol and copper in water can retard learning, other studies show feeding dietary cholesterol before learning can improve acquisition whereas feeding cholesterol after learning can degrade long-term memory. We explored this issue by manipulating cholesterol concentration and duration following classical trace conditioning of the rabbit's nictitating membrane response and assessed conditioned responding after eight weeks on cholesterol. First, rabbits given trace classical conditioning followed by 0.5%, 1%, or 2% cholesterol for eight weeks showed body weight and serum cholesterol levels that were a function of dietary cholesterol. Although all concentrations of cholesterol showed some sign of retarding long-term memory, the level of memory retardation was correlated with serum cholesterol levels. Second, rabbits given trace conditioning followed by different durations of a 2% cholesterol diet combined with different durations of a 0% control diet for 8 weeks showed duration and timing of a 2% cholesterol diet were important in affecting recall. The data support the idea that dietary cholesterol may retard long-term memory
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