942 research outputs found

    Reasons behind family refusal to organ donation in Sabah, Malaysia

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    Despite increased public awareness and the increase in the number of pledged organ donors, the actual number of organ donation in Sabah remains low due to the high rejection rate to donation by family members. This retrospective study aims to discover the main reasons of family refusal to organ donation in Sabah, besides attempting to determine whether the reasons of family refusal were significantly associated to the background of the next-of-kin. Descriptive statistics were used to describe the demography of the deceased and the next-of kin, as well as the reason of refusal. Meanwhile, Chisquare test and Kruskal-Wallis test were implemented to identify the significant associations. Not knowing the wish of deceased, unwilling to let the deceased to suffer, and concern over funeral delay stand out to be the most predominant reasons of family refusal. However, none of the background factors are significantly associated with reasons of family refusal to organ donation

    Long short‐distance topology modelling of 3D point cloud segmentation with a graph convolution neural network

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    3D point cloud segmentation is a non-trivial problem due to its irregular, sparse, and unordered data structure. Existing methods only consider structural relationships of a 3D point and its spatial neighbours. However, the inner-point interactions and long-distance context of a 3D point cloud have been less investigated. In this study, we propose an effective plug-and-play module called the Long Short-Distance Topologically Modelled (LSDTM) Graph Convolutional Neural Network (GCNN) to learn the underlying structure of 3D point clouds. Specifically, we introduce the concept of subgraph to model the contextual-point relationships within a short distance. Then the proposed topology can be reconstructed by recursive aggregation of subgraphs, and importantly, to propagate the contextual scope to a long range. The proposed LSDTM can parse the point cloud data with maximisation of preserving the geometric structure and contextual structure, and the topological graph can be trained end-to-end through a seamlessly integrated GCNN. We provide a case study of triple-layer ternary topology and experimental results on ShapeNetPart, Stanford 3D Indoor Semantics and ScanNet datasets, indicating a significant improvement on the task of 3D point cloud segmentation and validating the effectiveness of our research

    Evaluation of the Surface Energy Balance System (SEBS) applied to ASTER imagery with flux-measurements at the SPARC 2004 site (Barrax, Spain)

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    Accurate quantification of the amount and spatial variation of evapotranspiration is important in a wide range of disciplines. Remote sensing based surface energy balance models have been developed to estimate turbulent surface energy fluxes at different scales. The objective of this study is to evaluate the Surface Energy Balance System (SEBS) model on a landscape scale, using tower-based flux measurements at different land cover units during an overpass of the ASTER sensor over the SPARC 2004 experimental site in Barrax (Spain). A sensitivity analysis has been performed in order to investigate to which variable the sensible heat flux is most sensitive. Taking into account their estimation errors, the aerodynamic parameters (hc, z0M and d0) can cause large deviations in the modelling of sensible heat flux. The effect of replacement of empirical derivation of these aerodynamic parameters in the model by field estimates or literature values is investigated by testing two scenarios: the Empirical Scenario in which empirical equations are used to derive aerodynamic parameters and the Field Scenario in which values from field measurements or literature are used to replace the empirical calculations of the Empirical Scenario. In the case of a homogeneous land cover in the footprints of the measurements, the Field Scenario only resulted in a small improvement, compared to the Empirical Scenario. The Field Scenario can even worsen the result in the case of heterogeneous footprints, by creating sharp borders related to the land cover map. In both scenarios modelled fluxes correspond better with flux measurements over uniform land cover compared to cases where different land covers are mixed in the measurement footprint. Furthermore SEBS underestimates sensible heat flux especially over dry and sparsely vegetated areas, which is common in single-source models

    Droplet entrainment within the evaporator to the suitable volume-filling ratio of a vertical two-phase closed thermosyphon

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    The present study on vertical two-phase closed thermosyphon (TPCT) is aimed to determine the suitable volume-filling ratio, as a function of geometries, heat flux and vapor temperature, in order to avoid the potential local dryout in the evaporator section and hence to maximize the performance. In the study, the droplet entrainment, which is caused by the internal counter flow during the nucleate boiling within the falling liquid film in the evaporator section, is introduced to improve the existing TPCT model, so a comprehensive model with considering all three heat transfer regimes in the evaporator is further established. The suggested lower and upper limits of volume-filling ratio (CFR and EFR) are then determined by utilizing the criterias for local dryout, flooding limit and boiling limit. Furthermore, the effects of geometries, heat flux and vapor temperature on the range of volume-filling ratio are analyzed in details, a simplified correlation of CFR is then proposed based on the numerical modeling results. Particularly, the predictions of the distribution of falling film thickness and onset of flooding are validated with the published experimental data and other numerical simulation results. It is also found that the droplet entrainment significantly influences the thickness and distribution of the falling film. Increasing vapor temperature and inner diameter and decreasing the evaporator length significantly enlarge the volume-filling ratio range (between CFR and EFR), operation envelope (corresponding to boiling limit and flooding limit) of TPCT. Increasing the condenser length increases the volume-filling ratio range and operation envelope to a small extent. The influence mechanisms of the optimum filling ratio by the heat flux and geometries are complicated; however, a correlation of CFR can be obtained in a good agreement with the numerical modeling results within 30% deviation for the whole limited scope

    Specific characters of 16S rRNA gene and 16S-23S rRNA internal transcribed spacer sequences of Xylella fastidiosa pear leaf scorch strains

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    Pear leaf scorch, the only Xylella fastidiosa-induced disease reported from Taiwan, was found in area where the variety Hengshan (Pyrus pyrifolia) was grown. Strains of pear leaf scorch Xyl. fastidiosa (XF-PLS) shared similarities to strains of other host origins in the requirement of complex medium and the exhibition of rippled cell walls, however, recent serological and molecular biology studies showed difference among them. Five strains of XF-PLS were compared with 20 other strains originally isolated from almond, oleander, pecan, plum, peach, mulberry, grapes, citrus, coffee, and sycamore by sequence analyses of the 16S rRNA gene and 16S-23S rRNA internal transcribed spacer region (ITS). When sequences of 16S rRNA gene based on fragment size of 1,537-1,540 bp were compared, the similarity index among 5 XF-PLS strains was 99.3-99.8%, whereas it was 97.8-98.6% between XF-PLS strains and strains from other hosts. When sequences of 16S-23S rRNA ITS based on fragment size of 510-540 bp were compared, the similarity index among 5 XF-PLS strains was 99.0-100%, whereas it was 80.7-82% between XF-PLS strains and strains from other hosts. Multiple sequence alignments led to the identification of 5 polymorphic nucleotides in the 16S rRNA gene among the 25 Xyl. fastidiosa strains, and there were considerable variations in the nucleotide sequences of 16S-23S rRNA ITS between XF-PLS and the other 20 Xyl. fastidiosa strains. The phylogenetic trees revealed that XF-PLS strains were separated from strains of other hosts. Strains of other hosts were divided into four subgroups: strains from (1) oleander, (2) grape, almond M23 and mulberry, (3) citrus and coffee, and (4) pecan, peach, plum, sycamore and almond M12. Results indicate that XF-PLS strains were not closely related to the above-mentioned strains from other hosts and could possibly belong to a new subspecies of Xyl. fastidiosa

    Cosmological constraints on the generalized holographic dark energy

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    We use the Markov ChainMonte Carlo method to investigate global constraints on the generalized holographic (GH) dark energy with flat and non-flat universe from the current observed data: the Union2 dataset of type supernovae Ia (SNIa), high-redshift Gamma-Ray Bursts (GRBs), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. The most stringent constraints on the GH model parameter are obtained. In addition, it is found that the equation of state for this generalized holographic dark energy can cross over the phantom boundary wde =-1.Comment: 14 pages, 5 figures. arXiv admin note: significant text overlap with arXiv:1105.186

    The Kuiper Belt and Other Debris Disks

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    We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade
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