12,239 research outputs found

    Hybrid Flooding Scheme for Mobile Wireless Networks

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    A hybrid broadcast scheme for mobile wireless networks is proposed in this letter. The main objective is to combine different flooding schemes in order to solve the broadcast storm issue encountered by the simple flooding scheme. For this purpose, the density of nodes is taken into account using a density metric called expansion metric. In addition, in order to reduce the broken links due to mobility of nodes and increasing dissimilarity among the intermediate nodes, a forwarding zone criterion is included in the proposed schemes. The proposed approaches have been implemented and compared with pure probabilistic flooding, and simple flooding schemes

    Predicting clinical diagnosis in Huntington's disease: An imaging polymarker

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    Objective Huntington's disease (HD) gene carriers can be identified before clinical diagnosis; however, statistical models for predicting when overt motor symptoms will manifest are too imprecise to be useful at the level of the individual. Perfecting this prediction is integral to the search for disease modifying therapies. This study aimed to identify an imaging marker capable of reliably predicting realā€life clinical diagnosis in HD. Method A multivariate machine learning approach was applied to restingā€state and structural magnetic resonance imaging scans from 19 premanifest HD gene carriers (preHD, 8 of whom developed clinical disease in the 5 years postscanning) and 21 healthy controls. A classification model was developed using crossā€group comparisons between preHD and controls, and within the preHD group in relation to ā€œestimatedā€ and ā€œactualā€ proximity to disease onset. Imaging measures were modeled individually, and combined, and permutation modeling robustly tested classification accuracy. Results Classification performance for preHDs versus controls was greatest when all measures were combined. The resulting polymarker predicted converters with high accuracy, including those who were not expected to manifest in that time scale based on the currently adopted statistical models. Interpretation We propose that a holistic multivariate machine learning treatment of brain abnormalities in the premanifest phase can be used to accurately identify those patients within 5 years of developing motor features of HD, with implications for prognostication and preclinical trials

    Zebrafish fin regeneration involves transient serotonin synthesis

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    The zebrafish is a vertebrate organism capable of regenerating many of its organs. Notably, it can undergo epimorphic regeneration of its fins after amputation. This process occurs through the formation of a wound epithelium and the dedifferentiation of mesenchymal and boneā€forming cells, which form a proliferative blastema. Here, we report that the entry into the regenerative process involves the local synthesis of serotonin (5ā€hydroxytryptamine, 5ā€HT) in the injuryā€associated tissue. One day after wounding, intracellular accumulation of serotonin was induced in the stump below the amputation plane. During blastema formation, serotonin was detected in the mesenchyme at the vicinity of the amputation plane and in the apical wound epithelium. During the advanced outgrowth phase, this monoamine was no longer present in the blastema, suggesting a temporal involvement of serotonin in the postinjury area. We show the expression of two serotonin synthesizing enzymes, tryptophan hydroxylase 1a and 1b in the blastema, suggesting the local production of this monoamine. Neither depletion of serotonin by chemical inhibition of tryptophan hydroxylase, nor ectopic administration of this monoamine affected fin regeneration, indicating it does not play a role during this process. Finally, we found that the presence of serotonin during regeneration depends on fibroblast growth factor and retinoic acid signaling. Overall, our study demonstrates that the initiation of fin regeneration is associated with a transient synthesis of serotonin in the regrowing tissue

    Sea anemones may thrive in a high CO2 world

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    Increased seawater pCO 2, and in turn 'ocean acidification' (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO 2 gradient at Vulcano, Italy. Both gross photosynthesis (P G) and respiration (R) increased with pCO 2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO 2 stimulation) of metabolism. The increase of P G outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO 2 limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO 2, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO 2. Understanding how CO 2-enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress. Ā© 2012 Blackwell Publishing Ltd

    COVID-19 contact tracing apps: UK public perceptions

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    In order to combat the COVID-19 pandemic, policymakers around the globe have increasingly invested in digital health technologies to support the ā€˜test, track and traceā€™ approach of containing the spread of the novel coronavirus. These technologies include mobile ā€˜contact tracingā€™ applications (apps), which can trace individuals likely to have come into contact with those who have reported symptoms or tested positive for the virus and request that they self-isolate. This paper takes a critical public health perspective that advocates for ā€˜genuine participationā€™ in public health interventions and emphasises the need to take citizenā€™s knowledge into account during public health decision-making. In doing so, it presents and discusses the findings of a UK interview study that explored public views on the possibility of using a COVID-19 contact-tracing app public health intervention at the time the United Kingdom (UK) Government announced their decision to develop such a technology. Findings illustrated intervieweesā€™ range and degree of understandings, misconceptions, and concerns about the possibility of using an app. In particular, concerns about privacy and surveillance predominated. Interviewees associated these concerns much more broadly than health by identifying with pre-existent British national narratives associated with individual liberty and autonomy. In extending and contributing to ongoing sociological research with public health, we argue that understanding and responding to these matters is vital, and that our findings demonstrate the need for a forward-looking, anticipatory strategy for public engagement as part of the responsible innovation of the COVID-19 contact-tracing app in the UK
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