93 research outputs found

    Impact of Noise Power Uncertainty on the Performance of Wideband Spectrum Segmentation

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    The objective of this work is to investigate the impact of noise uncertainty on the performance of a wideband spectrum segmentation technique. We define metrics to quantify the degradation due to noise uncertainty and evaluate the performance using simulations. Our simulation results show that the noise uncertainty has detrimental effects especially for low SNR users

    Electrical characterization of MS and MIS structures on AlGaN/AlN/GaN heterostructures

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    The forward and reverse bias I-V, C-V, and G/ω-V characteristics of (Ni/Au) Schottky barrier diodes (SBDs) on the Al 0.22Ga 0.78N/AlN/GaN high-electron-mobility-transistor (HEMTs) without and with SiN x insulator layer were measured at room temperature in order to investigate the effects of the insulator layer (SiN x) on the main electrical parameters such as the ideality factor (n), zero-bias barrier height ( B0), series resistance (R s), interface-state density (N ss). The energy density distribution profiles of the N ss were obtained from the forward bias I-V characteristics by taking into account the voltage dependence of the effective barrier height ( e) and ideality factor (n V) of devices. In addition, the N ss as a function of E c-E ss was determined from the low-high frequency capacitance methods. It was found that the values of N ss and R s in SBD HEMTs decreases with increasing insulator layer thickness. © 2010 Elsevier Ltd. All rights reserved

    Conceptual design of a hydroelectric power plant for a rehabilitation project

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    This study presents the conceptual design of a hydroelectric power plant, as a part of a large scale rehabilitation project for an existing power plant in Antalya, Turkey. The aim of the rehabilitation project is to increase the power and efficiency of the plant and its scope includes CFD aided turbine design, model production and tests, the design, production and implementation of the turbine, generator and the SCADA system. This study is the first attempt, as a preliminary study, to handle the problem and perform a conceptual design of the hydroelectric power plant. The existing plant is modeled to estimate the head and flow rate characteristics at various sections of the system. The net head and flow rate of the turbine are estimated. Transient analyses of the system are also performed to evaluate water hammer characteristics. The results of the transient analyses provide the inputs for the design of by-pass pipeline and pressure relief valve. The estimated net head and flow rate from the simulations are used as inputs for the preliminary design. The dimensions of the spiral case, the diameter of the stay vanes and guide vanes, wicket gate heights, runner diameter and rotational speed, runaway characteristics and preliminary output power are determined. The best efficiency point and the design point of the turbine are also obtained as the net head versus the flow rate. These results provide an idea on the feasibility of the increase in power.Papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

    Mucosa-associated lymphoid tissue lymphoma of the duodenum together with multiple intra-abdominal thromboses and hepatitis C virus infection: a case report

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    Mucosa associated lymphoid tissue MALT lymphoma is a low grade malignancy that arises most commonly from the gastric mucosa. Small intestinal involvement is very rare. The causative relationship between Helicobacter pylori and the gastric MALT lymphoma is a well known issue, but recently there are several data suggesting the role of hepatitis C virus (HCV) infection in the pathogenesis of lymphoma including MALT lymphoma. Herein we present a rare case of duodenal MALT lymphoma with multiple intra-abdominal thromboses together with HCV infection that was confirmed by real-time polymerase chain reaction detecting HCV-RNA within the peripheral blood mononuclear cells

    Tannin- caprolactam and Tannin- PEG formulations as outdoor wood preservatives: Weathering properties

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    International audienceAbstractKey messageThis article presents the leaching, fire and weathering resistance improvements of samples treated with tannin-based wood preservatives added of caprolactam. PEG-added formulations show limited applicability. The FT-IR and13C-NMR analyses of the caprolactam-added formulations show some evidences of copolymerization.ContextTannin-boron wood preservatives are known for their high resistance against leaching, biological attacks, fire as well as for the good mechanical properties that they impart to wood. These properties promoted these formulations for being a candidate for the protection of green buildings. However, the low elasticity of these polymers and their dark colour implied limited weathering resistances.AimsThe aim of the study is to find suitable additives for tannin-based formulations to overcome their limited weathering resistances, without compromising the other properties.MethodsTreatment, leaching and fire tests, dimensional stability as well as artificial and natural weathering of the timber treated with caprolactam-added and PEG-added formulations were performed. FT-IR and 13C-NMR of the formulations were presented.ResultsThe presence of caprolactam improved the properties of the formulation with particularly significant results in terms of resistance against leaching and dimensional stability. These enhancements were imparted also to the weathering resistance of the tannin-caprolactam formulations. Indeed, the colour changes during the artificial and natural exposures were stable for longer periods. FT-IR and 13C-NMR investigations of the advanced formulations were led, and covalent copolymerization of the caprolactam with the tannin-hexamine polymer was observed.ConclusionThe tannin formulations with caprolactam improved the durability of the wood specimens, while the PEG-tannin presented strong application drawbacks

    In Vivo Methods to Study Uptake of Nanoparticles into the Brain

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    Several in vivo techniques have been developed to study and measure the uptake of CNS compounds into the brain. With these techniques, various parameters can be determined after drug administration, including the blood-to-brain influx constant (Kin), the permeability-surface area (PS) product, and the brain uptake index (BUI). These techniques have been mostly used for drugs that are expected to enter the brain via transmembrane diffusion or by carrier-mediated transcytosis. Drugs that have limitations in entering the brain via such pathways have been encapsulated in nanoparticles (based on lipids or synthetic polymers) to enhance brain uptake. Nanoparticles are different from CNS compounds in size, composition and uptake mechanisms. This has led to different methods and approaches to study brain uptake in vivo. Here we discuss the techniques generally used to measure nanoparticle uptake in addition to the techniques used for CNS compounds. Techniques include visualization methods, behavioral tests, and quantitative methods

    Acoustic Overexposure Increases the Expression of VGLUT-2 Mediated Projections from the Lateral Vestibular Nucleus to the Dorsal Cochlear Nucleus

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    The dorsal cochlear nucleus (DCN) is a first relay of the central auditory system as well as a site for integration of multimodal information. Vesicular glutamate transporters VGLUT-1 and VGLUT-2 selectively package glutamate into synaptic vesicles and are found to have different patterns of organization in the DCN. Whereas auditory nerve fibers predominantly co-label with VGLUT-1, somatosensory inputs predominantly co-label with VGLUT-2. Here, we used retrograde and anterograde transport of fluorescent conjugated dextran amine (DA) to demonstrate that the lateral vestibular nucleus (LVN) exhibits ipsilateral projections to both fusiform and deep layers of the rat DCN. Stimulating the LVN induced glutamatergic synaptic currents in fusiform cells and granule cell interneurones. We combined the dextran amine neuronal tracing method with immunohistochemistry and showed that labeled projections from the LVN are co-labeled with VGLUT-2 by contrast to VGLUT-1. Wistar rats were exposed to a loud single tone (15 kHz, 110 dB SPL) for 6 hours. Five days after acoustic overexposure, the level of expression of VGLUT-1 in the DCN was decreased whereas the level of expression of VGLUT-2 in the DCN was increased including terminals originating from the LVN. VGLUT-2 mediated projections from the LVN to the DCN are likely to play a role in the head position in response to sound. Amplification of VGLUT-2 expression after acoustic overexposure could be a compensatory mechanism from vestibular inputs in response to hearing loss and to a decrease of VGLUT-1 expression from auditory nerve fibers

    PREPARATION OF STABLE SBIS3 SOLS LABELED WITH TC-99M FOR USE IN THE DETECTION OF MALIGNANT-TUMORS

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    In this study a radiocolloid has been prepared for use in the detection of malignant tumors by scintigraphy. The radiocolloid is of lower toxicity than those proposed previously. Its ability to enable the detection of malignant tumors has been confirmed by its application to rabbit and human thyroids. Electron microscopic studies have also been performed to characterize Sb2S3 particles in the solution and to elucidate their interaction with a protective colloid
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