5,792 research outputs found

    Pyramidal Fisher Motion for Multiview Gait Recognition

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    Submitted to International Conference on Pattern Recognition, ICPR, 2014The goal of this paper is to identify individuals by analyzing their gait. Instead of using binary silhouettes as input data (as done in many previous works) we propose and evaluate the use of motion descriptors based on densely sampled short-term trajectories. We take advantage of state-of-the-art people detectors to define custom spatial configurations of the descriptors around the target person. Thus, obtaining a pyramidal representation of the gait motion. The local motion features (described by the Divergence-Curl-Shear descriptor) extracted on the different spatial areas of the person are combined into a single high-level gait descriptor by using the Fisher Vector encoding. The proposed approach, coined Pyramidal Fisher Motion, is experimentally validated on the recent `AVA Multiview Gait' dataset. The results show that this new approach achieves promising results in the problem of gait recognition

    RDF(S) Interoperability Results for Semantic Web Technologies

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    Interoperability among different development tools is not a straightforward task since ontology editors rely on specific internal knowledge models which are translated into common formats such as RDF(S). This paper addresses the urgent need for interoperability by providing an exhaustive set of benchmark suites for evaluating RDF(S) import, export and interoperability. It also demonstrates, in an extensive field study, the state of-the-art of interoperability among six Semantic Web tools. From this field study we have compiled a comprehensive set of practices that may serve as recommendations for Semantic Web tool developers and ontology engineers

    Coupled Analysis of Thorium-based Fuels in the High-Performance Light Water Reactor Fuel Assembly

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    One of the six selected concepts to be part of Generation IV nuclear reactors is the Supercritical Light Water Cooled Reactor. The High-Performance Light Water Reactor (HPLWR) is the European version and it is a very promising design. In recent years, interest in the study of thorium-based fuel cycles has been renewed and its possibilities for current LWRs have been evaluated. The use of thorium-based fuels will be fundamental in the future sustainability of nuclear energy, since in addition to its abundance in nature, thorium has an important group of advantages. In this paper, performance of thorium-based fuels in the typical fuel assembly of the HPLWR reactor is evaluated, using a computational model based on CFD and Monte Carlo codes for the neutronic/thermal-hydraulic coupled analysis. The volumetric power density profiles, coolant temperature profiles, fuel temperature profiles and others are compared with those obtained for standard UO2 fuel. When the thorium-based fuels are used, the obtained infinite multiplication coefficients are smaller than the value obtained when UO2 is used, since the 232Th isotope has a lower contribution to the multiplicative properties of the medium than 238U. As a result, a difference of approximately 12 000 pcm was observed. The results verified that the HPLWR is a thermal reactor with a hard spectrum. There are no notable changes in the neutron spectrum if the mass fraction of thorium is slightly varied.  With coupled analysis, the potential benefits of the utilization of thorium-based fuels were verified. Moreover, a significant temperature decrease by 136 K on the center line of the fuel elements was observed. When the mass fraction of thorium increases in the oxides mixture, the weighted average temperature on the fuel elements decreases

    Ramon (\u3ci\u3eBrosimun alicastrum\u3c/i\u3e) Foliage as Supplement for Lactating Dual Purpose Cows

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    The objective of the present study was to asses the value of ramón (Brosimun alicastrum) foliage as a N-source in replacement of soybean-N in lactating dual purpose cows (Bos indicus x B. taurus). Four lactating cows were used in a latin rectangle design. Ramón was included to replace 0, 33, 66 and 100 % of the soybean-N contained in the supplement. Basal diet was fresh “Taiwán” a cultivar of Elephant grass (Pennisetum purpureum) fed ad libitum. Basal and total dry matter intake, digestibility (total fecal collection), saleable and calf suckled milk yields, and milk composition (fat, protein and lactose) were measured over 15 d periods. Ramon increased the yield of milk constituents (P\u3c 0.05) over those obtained with Taiwán-grass alone, but was inferior (P\u3c 0.05) when soybean was the N source. Total milk yield was reduced 18% in Ramón supplemented cows compared with those supplemented with soybean. Digestibility of dry matter, organic matter and fiber was reduced by Ramón inclusion probably due to its higher fiber and ash content as compared with soybean meal. It was concluded that, although animal performance was not achieved as with soybean meal, supplementing with Ramón is a better strategy than relying on grass alone

    Searching for galactic sources in the Swift GRB catalog

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    Since the early 1990s Gamma Ray Bursts have been accepted to be of extra-galactic origin due to the isotropic distribution observed by BATSE and the redshifts observed via absorption line spectroscopy. Nevertheless, upon further examination at least one case turned out to be of galactic origin. This particular event presented a Fast Rise, Exponential Decay (FRED) structure which leads us to believe that other FRED sources might also be Galactic. This study was set out to estimate the most probable degree of contamination by galactic sources that certain samples of FREDs have. In order to quantify the degree of anisotropy the average dipolar and quadripolar moments of each sample of GRBs with respect to the galactic plane were calculated. This was then compared to the probability distribution of simulated samples comprised of a combination of isotropically generated sources and galactic sources. We observe that the dipolar and quadripolar moments of the selected subsamples of FREDs are found more than two standard deviations outside those of random isotropically generated samples.The most probable degree of contamination by galactic sources for the FRED GRBs of the Swift catalog detected until February 2011 that do not have a known redshift is about 21 out of 77 sources which is roughly equal to 27%. Furthermore we observe, that by removing from this sample those bursts that may have any type of indirect redshift indicator and multiple peaks gives the most probable contamination increases up to 34% (17 out of 49 sources). It is probable that a high degree of contamination by galactic sources occurs among the single peak FREDs observed by Swift.Comment: Published to A&A, 4 pages, 5 figures, this arXiv version includes appended table with all the bursts considered in this stud

    A CMOS 0.8 μm fully differential current mode buffer for HF SI circuits

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    El pdf del artículo es la versión post-print.We present a high-frequency fully-differential current-mode buffer to interface off-chip currents with no significant degradation of the frequency response, and to measure current-mode ICs using standard equipment. It has been fabricated in a 0.8μm double-poly double-metal CMOS technology and features more than 37MHz bandwidth. In order to show its functionality, this unit has been incorporated to the front end of a Switched-Current Band-Pass ΣΔ modulator featuring 9 bit dynamic range at 10MHz clock frequency for a 30kHz signal bandwidth centered at 2.5MHz.Peer reviewe

    Polymorphic transformation from body-centered to face-centered cubic vanadium metal during mechanosynthesis of nanostructured vanadium nitride determined by extended x-ray absorption fine structure spectroscopy

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    The pathway for vanadium nitride VN formation obtained by milling treatment has been traced out. At the initial stages of the process, the reactant, vanadium metal, showing body-centered cubic bcc structure, becomes highly distorted. Simultaneously, the formation of a small nucleus of the product, VN, takes place. X-ray absorption spectroscopy XAS has allowed the quantification of the distortion degree as well as the detection of the VN nucleus in the early stages of their formation, while other standard structural characterization techniques are unable to detect such phenomena. For increasing milling times, apart from the expected increase in the size of the VN nucleus, a polymorphic transformation from bcc to fcc vanadium metal has been recorded. This phase might play a key role in the overall synthesis process and could be a reaction intermediate in other solid state processes involving V metal. The sensitivity of XAS to noncrystalline domains and to highly distorted environments, as well as the use of high resolution x-ray diffraction, has provided the relevant information to understand the whole reaction process.European Synchrotron Radiation Facility (ESRF)-ME-737SpLine CRG (beamline BM25 at the ESRF)-25- 01-657Ministerio de Educación y Ciencias de España-BQU2002-04364-C02-01 y BQU2002- 04364-C02-

    Decomposition and biological colonization of native and exotic leaf litter in a Central Spain stream

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    Riparian invasion by exotic trees may lead to changes in the quality of leaf-litter inputs to freshwater ecosystems. Leaflitter inputs are especially important in headwater streams, where aquatic food webs largely depend on the organic matter provided by the terrestrial vegetation. In a headwater stream of Central Spain, North of Guadalajara Province (Tagus basin) we compared the decomposition and biological colonization of leaf litter among two exotic (Ailanthus altissima Mill. Swingle and Robinia pseudoacacia L.) and two native trees (Fraxinus angustifolia Vahl. and Populus alba L.) co-existing in riparian zones. We hypothesized a lower biological colonization of exotic leaves due to organisms have not co-evolved with the exotic trees according to the Novel Weapons Hypothesis (NWH) and, consequently, lower decomposition rates of exotic leaves. To test our hypothesis, litter bags with different mesh sizes (coarse (C) and fine (F)), were used to distinguish between the total and microbial decomposition. The litter bags were placed in the stream and recovered after 2, 20, 39, 62 and 82 days of incubation. After each collection, we assessed the amount of remaining litter, analysed the nitrogen (N) and phosphorous (P) in the litter, identified the macroinvertebrates and quantified the fungal biomass. Consistent with our hypothesis, we found greater fungal biomass buildup on native leaves than on exotic leaves. However, decomposition rates (k) were species-specific, being the ranking in C-bags (A. altissima = F. angustifolia > P. alba > R. pseudoacacia) slightly different than in F-bags (A. altissima > F. angustifolia > P. alba > R. pseudoacacia). The k in both the C-bags and F-bags were correlated with leaf traits, such as lignin, acid detergent fibre (ADF) and lignin:P. There was not a clear effect of the exotic species on macroinvertebrate variables, but the contribution of macroinvertebrates to litter decomposition was lower in exotic litter than in native litter, as shown by a lower ratio between k in C-bags and k in F-bags (kC : kF). Our results supported that invasive species might impact both biological colonization and decomposition rates in stream ecosystems by the addition of different quality leaf litter when compared to native vegetation. The differences in the biological colonization may be explained by the NWH, but differences in the decomposition rates were better explained by litter quality
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