983 resultados para frequency-doubling efficiency


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The adequate selection of indicator groups of biodiversity is an important aspect of the systematic conservation planning. However, these assessments differ in the spatial scale, in the methods used and in the groups considered to accomplish this task, which generally produces contradictory results. The quantification of the spatial congruence between species richness and complementarity among different taxonomic groups is a fundamental step to identify potential indicator groups. Using a constructive approach, the main purposes of this study were to evaluate the performance and efficiency of eight potential indicator groups representing amphibian diversity in the Brazilian Atlantic Forest. Data on the geographic range of amphibian species that occur in the Brazilian Atlantic Forest was overlapped to the full geographic extent of the biome, which was divided into a regular equal-area grid. Optimization routines based on the concept of complementarily were applied to verify the performance of each indicator group selected in relation to the representativeness of the amphibians in the Brazilian Atlantic Forest as a whole, which were solved by the algorithm"simulated annealing", through the use of the software MARXAN. Some indicator groups were substantially more effective than others in regards to the representation of the taxonomic groups assessed, which was confirmed by the high significance of data (F = 312.76; p < 0.01). Leiuperidae was considered as the best indicator group among the families analyzed, as it showed a good performance, representing 71% of amphibian species in the Brazilian Atlantic Forest (i.e. 290 species), which may be associated with the diffuse geographic distribution of its species. This study promotes understanding of how the diversity standards of amphibians can be informative for systematic conservation planning on a regional scale.

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Pumppaaminen kuluttaa teollisuudessa huomattavan osan energiasta, joten siellä on myös merkittäviä säästömahdollisuuksia. Maailmanlaajuisesti pumppaus kuluttaa noin viidenneksen sähkömoottorien energiantarpeesta, ja tietyillä teollisuudentoimialoilla jopa yli 50%. Jätevedenpumppaus perustuu edelleenkin pääosin 50- ja 60- luvuilla kehitettyyn tekniikkaan, merkittäviä energiansäästöjä on mahdollista saavuttaa suhteellisen pienillä investoinneilla. Työn teoriaosassa käsitellään perusteet jätevedenkäsittelystä, ja viemäriputkiston rakenteesta. Pumppuja, sähkömoottoreita ja taajuusmuuttajia käsitellään laajemmin keskittyen niiden toimintaan ja toimintaa ohjaaviin teorioihin. Empiirisessä osassa tutkitaan uuden teknologian energiansäästöpotentiaalia erilaisilla mittauksilla, sekä mittausten pohjalta tehdyillä case-analyyseillä. Näitä analyysejä varten työn aikana kehiteltiin laskin, jolla voidaan arvioida energian kulutusta tunnetulle pumpulle, kun tiedetään haluttu toimintapiste. Työssä käsitelty uusi teknologia on mahdollisesti merkittävin uudistus viemäriveden pumppausteknologiaan taajuusmuuttajien käyttöönoton jälkeen. Teknologialla päästään eroon imukaivoista liki täysin, ja sitä kautta saadaan paremmin hallittua monia ongelmia kuten hajuhaittoja. Teknologian merkittävin hyöty on kuitenkin energiansäästö. Perinteisessä teknologiassa taajuusmuuttajat ovat olleet kannattavia, mikäli geodeettisen nostokorkeuden osuus on mahdollisimman pieni. Tyypillisessä uuden teknologian sovelluskohteissa geodeettinen nostokorkeus tulee yleensä olemaan pieni, joten uuden teknologian käyttöönoton kannattavuus on näissä kohteissa erityisen hyvä.

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We report on a field-effect light emitting device based on silicon nanocrystals in silicon oxide deposited by plasma-enhanced chemical vapor deposition. The device shows high power efficiency and long lifetime. The power efficiency is enhanced up to 0.1 %25 by the presence of a silicon nitride control layer. The leakage current reduction induced by this nitride buffer effectively increases the power efficiency two orders of magnitude with regard to similarly processed devices with solely oxide. In addition, the nitride cools down the electrons that reach the polycrystalline silicon gate lowering the formation of defects, which significantly reduces the device degradation.

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PURPOSE: The goal of this study was to explore the effect of lifelong aerobic exercise (i.e., chronic training) on skeletal muscle substrate stores (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, and oxidative capacity (ox), in older endurance-trained master athletes (OA) compared with noncompetitive recreational younger (YA) athletes matched by frequency and mode of training. METHODS: Thirteen OA (64.8 ± 4.9 yr) exercising 5 times per week or more were compared with 14 YA (27.8 ± 4.9 yr) males and females. IMTG, glycogen, fiber types, succinate dehydrogenase, and capillarization were measured by immunohistochemistry in vastus lateralis biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry before and after an insulin clamp and during a cycle ergometer graded maximal test. RESULTS: V˙O2peak was lower in OA than YA. The OA had greater IMTG in all fiber types and lower glycogen stores than YA. This was reflected in greater proportion of type I and less type II fibers in OA. Type I fibers were similar in size, whereas type II fibers were smaller in OA compared with YA. Both groups had similar succinate dehydrogenase content. Numbers of capillaries per fiber were reduced in OA but with a higher number of capillaries per area. Metabolic flexibility and insulin sensitivity were similar in both groups. Exercise metabolic efficiency was higher in OA. At moderate exercise intensities, carbohydrate-ox was lower in OA but with similar Fat-ox. CONCLUSIONS: Lifelong exercise is associated with higher IMTG content in all muscle fibers and higher metabolic efficiency during exercise that are not explained by differences in muscle fibers types and other muscle characteristics when comparing older with younger athletes matched by exercise mode and frequency.

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The purpose of this study was to estimate the energy cost of linear (EC) and vertical displacement (ECvert), mechanical efficiency and main stride parameters during simulated ski mountaineering at different speeds and gradients, to identify an optimal speed and gradient that maximizes performance. 12 subjects roller skied on a treadmill at three different inclines (10, 17 and 24 %) at three different speeds (approximately 70, 80 and 85 % of estimated peak heart rate). Energy expenditure was calculated by indirect calorimetry, while biomechanical parameters were measured with an inertial sensor-based system. At 10 % there was no significant change with speed in EC, ECvert and mechanical efficiency. At 17 and 24 % the fastest speed was significantly more economical. There was a significant effect of gradient on EC, ECvert and mechanical efficiency. The most economical gradient was the steepest one. There was a significant increase of stride frequency with speed. At steep gradients only, relative thrust phase duration decreased significantly, while stride length increased significantly with speed. There was a significant effect of gradient on stride length (decrease with steepness) and relative thrust phase duration (increase with steepness). A combination of a decreased relative thrust phase duration with increased stride length and frequency decreases ECvert. To minimize the energy expenditure to reach the top of a mountain and to optimize performance, ski-mountaineers should choose a steep gradient (~24 %) and, provided they possess sufficient metabolic scope, combine it with a fast speed (~6 km h(-1)).

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AbstractThe present essay is aimed at getting the radiologist familiar with the basic histological skin structure, allowing for a better correlation with sonographic findings. A high-frequency (22 MHz) ultrasonography apparatus was utilized in the present study. The histological analysis was performed after the skin specimens fixation with formalin, inclusion in paraffin blocks and subsequent staining with hematoxylin-eosin. The authors present a literature review showing the relationship between sonographic and histological findings in normal cutaneous tissue, and discuss the technique for a better performance of the sonographic scan. High-frequency ultrasonography is an excellent tool for the diagnosis of different skin conditions. However, as this method is operator-dependent, it is crucial to understand the normal skin structure as well as the correlation between histological and sonographic findings.

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NlmCategory="UNASSIGNED">As opposed to the standard detective quantum efficiency (DQE), effective DQE (eDQE) is a figure of merit that allows comparing the performances of imaging systems in the presence of scatter rejection devices. The geometry of the EOS™ slot-scanning system is such that the detector is self-collimated and rejects scattered radiation. In this study, the EOS system was characterised using the eDQE in imaging conditions similar to those used in clinical practice: with phantoms of different widths placed in the X-ray beam, for various incident air kerma and tube voltages corresponding to the phantom thickness. Scatter fractions in EOS images were extremely low, around 2 % for all configurations. Maximum eDQE values spanned 9-14.8 % for a large range of air kerma at the detector plane from 0.01 to 1.34 µGy. These figures were obtained with non-optimised EOS setting but still over-performed most of the maximum eDQEs recently assessed for various computed radiology and digital radiology systems with antiscatter grids.