579 research outputs found

    Influence of local habitat on the physiological responses of large benthic foraminifera to temperature and nutrient stress

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    Large benthic foraminifera (LBF) are important for reef sediment formation, but sensitive to elevated temperature and nutrients. However, it is possible that conspecific foraminifera living in different reef sites present divergent response to environmental shifts. We investigated how populations of Amphistegina lobifera from reef sites located along a temperature and nutrient gradient of the northern Great Barrier Reef respond and acclimate to elevated temperature and nitrate under lab-controlled conditions. Generalized linear mixed models showed that interaction between reef sites and temperature or nitrate conditions had a significant effect on survivorship, bleaching frequency and growth rates of A. lobifera. Further physiological analyses of antioxidant capacity and Ca-ATPase activity showed that populations collected from the inner-shelf sites (highest nutrient levels, largest temperature variation) were consistently able to acclimate to both parameters after 30 days. In contrast, foraminifera collected from the reef sites located in the mid- and outer-shelfs were significantly more sensitive to elevated temperatures and nitrate. Our results highlight the importance of local habitat in shaping the tolerance of LBF to changing environmental conditions; populations that live in stable environments are more sensitive to elevated temperature and nitrate, even within their fundamental tolerance range, than those that experience fluctuating conditions

    On the stability of point cloud machine learning based coding

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    This paper analyses the performance of two of the most well known deep learning-based point cloud coding solutions, considering the training conditions. Several works have recently been published on point cloud machine learning-based coding, following the recent tendency on image coding. These codecs are typically seen as a set of predefined trained machines. However, the performance of such models is usually very dependent of their training, and little work has been considered on the stability of the codecs’ performance, as well as the possible influence of the loss function parameters, and the increasing number of training epochs. The evaluation experiments are supported in a generic test set with point clouds representing objects and also more complex scenes, using the point to point metric (PSNR D1), as several studies revealed the good quality representation of this geometry-only point cloud metric.Research funded by the Portuguese FCT-Fundação para a Ciência e Tecnologia under the project UIDB/50008/2020, PLive X-0017-LX-20, and by operation Centro-01-0145-FEDER-000019 - C4 - Centro de Competencias em Cloud Computing.info:eu-repo/semantics/acceptedVersio

    Quality Evaluation of Machine Learning-based Point Cloud Coding Solutions

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    In this paper, a quality evaluation of three point cloud coding solutions based on machine learning technology is presented, notably, ADLPCC, PCC_GEO_CNN, and PCGC, as well as LUT_SR, which uses multi-resolution Look-Up Tables. Moreover, the MPEG G-PCC was used as an anchor. A set of six point clouds, representing both landscapes and objects were coded using the five encoders at different bit rates, and a subjective test, where the distorted and reference point clouds were rotated in a video sequence side by side, is carried out to assess their performance. Furthermore, the performance of point cloud objective quality metrics that usually provide a good representation of the coded content is analyzed against the subjective evaluation results. The obtained results suggest that some of these metrics fail to provide a good representation of the perceived quality, and thus are not suitable to evaluate some distortions created by machine learning-based solutions. A comparison between the analyzed metrics and the type of represented scene or codec is also presented.This research was funded by the Portuguese FCT-Fundação para a Ciência e Tecnologia under the project UIDB/50008/2020, PLive X-0017-LX-20, and by operation Centro-01-0145-FEDER-000019 - C4 - Centro de Competencias em Cloud Computing.info:eu-repo/semantics/acceptedVersio

    Subjective Quality Evaluation of Point Clouds Using a Head Mounted Display

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    This paper reports on a subjective quality evaluation of static point clouds encoded with the MPEG codecs V-PCC and G-PCC, the deep learning-based codec RS-DLPCC, and the popular Draco codec. 18 subjects visualized 3D representations of distorted point clouds using a Head Mounted Display, which allowed for a direct comparison with their reference. The Mean Opinion Scores (MOS) obtained in this subjective evaluation were compared with the MOS from two previous studies, where the same content was visualized either on a 2D display or a 3D stereoscopic display, through the Pearson Correlation, Spearman Rank Order Correlation, Root Mean Square Error, and the Outlier Ratio. The results indicate that the three studies are highly correlated with one another. Moreover, a statistical analysis between all evaluations showed no significant differences between them

    Purification of plasmid DNA vectors by aqueous two-phase extraction and hydrophobic interaction chromatography

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    The current study explores the possibility of using a polyethyleneglycol(PEG)/ammonium sulphate aqueous two-phase system (ATPS) as an early step in a process for the purification of a model 6.1 kbp plasmid DNA (pDNA) vector. Neutralised alkaline lysates were fed directly to ATPS. Conditions were selected to direct pDNA towards the salt-rich bottom phase, so that this stream could be subsequently processed by hydrophobic interaction chromatography (HIC). Screening of the best conditions for ATPS extraction was performed using three PEG molecular weights (300, 400, 600) and varying the tie-line length, phase volume ratio and lysate load. For a 20 % (w/w) lysate load, the best results were obtained with PEG 600 using the shortest tie-line (38.16 % w/w). By further manipulating the system composition along this tie-line in order to obtain a top/bottom phase volume ratio of 9.3 (35 % w/w PEG 600, 6% w/w NH4)2SO4), it was possible to recover 100 % of pDNA in the bottom phase with a 3-fold increase in concentration. Further increase in the lysate load up to 40 %(w/w) with this system resulted in a 8-fold increase in pDNA concentration, but with a yield loss of 15 %. The ATPS extraction was integrated with HIC and the overall process compared with a previously defined process that uses sequential precipitations with isopropanol and ammonium sulphate prior to HIC. Although the final yield is lower in the ATPS-based process the purity grade of the final pDNA product is higher. This shows that it is possible to substitute the time-consuming two-step precipitation procedure by a simple ATPS extraction.Portuguese Ministry of Science and Technology - POCTI/BIO/47245/2002

    Unpacking distinction within mobility : social prestige and international students

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    Author thanks the Social Sciences and Humanities Research Council of Canada (SSHRC) for their funding on this projecThis paper investigates the complex ways in which young people engage in social distinction within international mobility. The study offers novel conceptual and empirical insights by examining how distinction and social advantage is reproduced through short‐term student mobility from the Global North to the Global South. In doing so, it elucidates the iterative process of distinction‐making within mobility and argues that young mobile people negotiate a tension between different forms of distinction. Specifically, it unpacks and conceptualises distinction into dual categories—collective and individual—and suggests that students alternate and waver between these categories in order to both validate and elevate their position within a mobility hierarchy. The paper also considers how particular places are viewed as more distinctive and affording greater gains in cultural and symbolic capital. It concludes with future interrogations and ways forward for research on international mobility and distinction.PostprintPeer reviewe

    The Relationship between Sun Exposure, Dietary Vitamin D and Muscle Soreness in Collegiate Football Players

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    Background: A growing body of research is raising concern regarding the prevalence of poor vitamin D status among athletes. Besides it’s well known association with low bone mineral density, an addition sign of vitamin D deficiency is muscular weakness and soreness, suggesting that deficiency in athletic populations may inhibit optimal physical performance and increase the risk of injury. It is difficult to achieve optimal vitamin D status through diet alone, so it is important to assess all sources of vitamin D, including dietary intake, supplementation, and amount and frequency of sun exposure to obtain a comprehensive profile of vitamin D risk. Currently, there are no studies that include such a complete profile of vitamin D risk in collegiate football players. Purpose: The purpose of this study is to investigate the associations between sun exposure and diet, as markers of vitamin D status, and training-induced muscle soreness in collegiate football players. More specifically, this study assesses if total sun exposure and dietary vitamin D intake are related to muscle soreness. Methods: Twenty-four male collegiate football players were recruited for this cross-sectional study in October 2015. Player body composition was measured using a multi-current bioelectrical impedance analyzer (BIA). Dietary intake, sun exposure, and muscle soreness data were collected via interview. The Sun Exposure Questionnaire and the Short Form McGill Pain Questionnaire (SF-MPQ) were used to assess weekly sun exposure and muscle soreness, respectively. Results: The mean vitamin D intake (10.8±9.5 mcg) was below the RDA for vitamin D (15 mcg), with only 7 participants (29.2%) meeting or exceeding the RDA. Dietary vitamin D intake was inversely associated with portion of muscle sore (rs = -0.393, p = 0.029). SF-MPQ total and affective scores were each inversely associated with weekly time outdoors (rs = -0.362, p = 0.041; rs = -0.449, p = 0.014, respectively). T-test analysis found that the mean SF-MPQ affective pain score was significantly lower for players with a time outdoors score above the mean (p = 0.04). Conclusion: There is a high prevalence of insufficient dietary vitamin D intake (70.8%) identified in a collegiate football team. Our findings suggest that higher dietary vitamin D intake and more time spent outdoors are associated with a lower proportion of muscular soreness and decreased perceived pain. Thus, achieving a satisfactory vitamin D status, through a combination of diet and sun exposure, may reduce vitamin D deficiency associated risks, including lowering muscle soreness, thereby serving to enhance athletic performance

    Optimising mRNA vaccines manufacturing by using Machine learning approaches

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