224 research outputs found

    Motion processing deficits in migraine are related to contrast sensitivity

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    Background: There are conflicting reports concerning the ability of people with migraine to detect and discriminate visual motion. Previous studies used different displays and none adequately assessed other parameters that could affect performance, such as those that could indicate precortical dysfunction. Methods: Motion-direction detection, discrimination and relative motion thresholds were compared from participants with and without migraine. Potentially relevant visual covariates were included (contrast sensitivity; acuity; stereopsis; visual discomfort, stress, triggers; dyslexia). Results: For each task, migraine participants were less accurate than a control group and had impaired contrast sensitivity, greater visual discomfort, visual stress and visual triggers. Only contrast sensitivity correlated with performance on each motion task; it also mediated performance. Conclusions: Impaired performance on certain motion tasks can be attributed to impaired contrast sensitivity early in the visual system rather than a deficit in cortical motion processing per se. There were, however, additional differences for global and relative motion thresholds embedded in noise, suggesting changes in extrastriate cortex in migraine. Tasks to study the effects of noise on performance at different levels of the visual system and across modalities are recommended. A battery of standard visual tests should be included in any future work on the visual system and migraine

    Chromite Crystal Structure and Chemistry applied as an Exploration Tool

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    The spinel group minerals have long been of interest to the geosciences due to their use as indicator minerals. Unit cell is a structural measure controlled by composition but is also affected by pressure and temperature relations through order-disorder. This study attempted to look at the applications of unit cell in exploration. The implementation of µXRD for this purpose required the creation the Slice Integration Technique to improve signal over background. Compositions of binary spinels can be approximated through their correlation with unit cell. Possible applications include gemology and curatorial studies, where the nondestructive nature of µXRD is highly advantageous and kimberlite vs non-kimberlite discrimination. The analysis of an indicator mineral was conducted using a field portable XRD and could determine isostructural grains in a field setting or unit cell could be used in the field in conjunction with other new field-portable technologies

    Multi-Service Group Key Management for High Speed Wireless Mobile Multicast Networks

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    YesRecently there is a high demand from the Internet Service Providers to transmit multimedia services over high speed wireless networks. These networks are characterized by high mobility receivers which perform frequent handoffs across homogenous and heterogeneous access networks while maintaining seamless connectivity to the multimedia services. In order to ensure secure delivery of multimedia services to legitimate group members, the conventional cluster based group key management (GKM) schemes for securing group communication over wireless mobile multicast networks have been proposed. However, they lack efficiency in rekeying the group key in the presence of high mobility users which concurrently subscribe to multiple multicast services that co-exist in the same network. This paper proposes an efficient multi-service group key management scheme (SMGKM) suitable for high mobility users which perform frequent handoffs while participating seamlessly in multiple multicast services. The users are expected to drop subscriptions after multiple cluster visits hence inducing huge key management overhead due to rekeying the previously visited cluster keys. The already proposed multi-service SMGKM system with completely decentralised authentication and key management functions is adopted to meet the demands for high mobility environment with the same level of security. Through comparisons with existing GKM schemes and simulations, SMGKM shows resource economy in terms of reduced communication and less storage overheads in a high speed environment with multiple visits

    Are markers of inflammation more strongly associated with risk for fatal than for nonfatal vascular events?

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    <p><b>Background:</b> Circulating inflammatory markers may more strongly relate to risk of fatal versus nonfatal cardiovascular disease (CVD) events, but robust prospective evidence is lacking. We tested whether interleukin (IL)-6, C-reactive protein (CRP), and fibrinogen more strongly associate with fatal compared to nonfatal myocardial infarction (MI) and stroke.</p> <p><b>Methods and Findings:</b> In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER), baseline inflammatory markers in up to 5,680 men and women aged 70-82 y were related to risk for endpoints; nonfatal CVD (i.e., nonfatal MI and nonfatal stroke [n = 672]), fatal CVD (n = 190), death from other CV causes (n = 38), and non-CVD mortality (n = 300), over 3.2-y follow-up. Elevations in baseline IL-6 levels were significantly (p = 0.0009; competing risks model analysis) more strongly associated with fatal CVD (hazard ratio [HR] for 1 log unit increase in IL-6 1.75, 95% confidence interval [CI] 1.44-2.12) than with risk of nonfatal CVD (1.17, 95% CI 1.04-1.31), in analyses adjusted for treatment allocation. The findings were consistent in a fully adjusted model. These broad trends were similar for CRP and, to a lesser extent, for fibrinogen. The results were also similar in placebo and statin recipients (i.e., no interaction). The C-statistic for fatal CVD using traditional risk factors was significantly (+0.017; p<0.0001) improved by inclusion of IL-6 but not so for nonfatal CVD events (p = 0.20).</p> <p><b>Conclusions:</b> In PROSPER, inflammatory markers, in particular IL-6 and CRP, are more strongly associated with risk of fatal vascular events than nonfatal vascular events. These novel observations may have important implications for better understanding aetiology of CVD mortality, and have potential clinical relevance.</p&gt

    A global spectral library to characterize the world's soil

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    Soil provides ecosystem services, supports human health and habitation, stores carbon and regulates emissions of greenhouse gases. Unprecedented pressures on soil from degradation and urbanization are threatening agro-ecological balances and food security. It is important that we learn more about soil to sustainably manage and preserve it for future generations. To this end, we developed and analyzed a global soil visible-near infrared (vis-NIR) spectral library. It is currently the largest and most diverse database of its kind. We show that the information encoded in the spectra can describe soil composition and be associated to land cover and its global geographic distribution, which acts as a surrogate for global climate variability. We also show the usefulness of the global spectra for predicting soil attributes such as soil organic and inorganic carbon, clay, silt, sand and iron contents, cation exchange capacity, and pH. Using wavelets to treat the spectra, which were recorded in different laboratories using different spectrometers and methods, helped to improve the spectroscopic modelling. We found that modelling a diverse set of spectra with a machine learning algorithm can find the local relationships in the data to produce accurate predictions of soil properties. The spectroscopic models that we derived are parsimonious and robust, and using them we derived a harmonized global soil attribute dataset, which might serve to facilitate research on soil at the global scale. This spectroscopic approach should help to deal with the shortage of data on soil to better understand it and to meet the growing demand for information to assess and monitor soil at scales ranging from regional to global. New contributions to the library are encouraged so that this work and our collaboration might progress to develop a dynamic and easily updatable database with better global coverage. We hope that this work will reinvigorate our community's discussion towards larger, more coordinated collaborations. We also hope that use of the database will deepen our understanding of soil so that we might sustainably manage it and extend the research outcomes of the soil, earth and environmental sciences towards applications that we have not yet dreamed of

    A study of charged kappa in J/ψ→K±Ksπ∓π0J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0

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    Based on 58×10658 \times 10^6 J/ψJ/\psi events collected by BESII, the decay J/ψ→K±Ksπ∓π0J/\psi \to K^{\pm} K_s \pi^{\mp} \pi^0 is studied. In the invariant mass spectrum recoiling against the charged K∗(892)±K^*(892)^{\pm}, the charged κ\kappa particle is found as a low mass enhancement. If a Breit-Wigner function of constant width is used to parameterize the kappa, its pole locates at (849±77−14+18)−i(256±40−22+46)(849 \pm 77 ^{+18}_{-14}) -i (256 \pm 40 ^{+46}_{-22}) MeV/c2c^2. Also in this channel, the decay J/ψ→K∗(892)+K∗(892)−J/\psi \to K^*(892)^+ K^*(892)^- is observed for the first time. Its branching ratio is (1.00±0.19−0.32+0.11)×10−3(1.00 \pm 0.19 ^{+0.11}_{-0.32}) \times 10^{-3}.Comment: 14 pages, 4 figure

    Measurement of the Michel Parameters in Leptonic Tau Decays

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    The Michel parameters of the leptonic tau decays are measured using the OPAL detector at LEP. The Michel parameters are extracted from the energy spectra of the charged decay leptons and from their energy-energy correlations. A new method involving a global likelihood fit of Monte Carlo generated events with complete detector simulation and background treatment has been applied to the data recorded at center-of-mass energies close to sqrt(s) = M(Z) corresponding to an integrated luminosity of 155 pb-1 during the years 1990 to 1995. If e-mu universality is assumed and inferring the tau polarization from neutral current data, the measured Michel parameters are extracted. Limits on non-standard coupling constants and on the masses of new gauge bosons are obtained. The results are in agreement with the V-A prediction of the Standard Model.Comment: 32 pages, LaTeX, 9 eps figures included, submitted to the European Physical Journal

    Clinic-level factors associated with retention in care among people living with human immunodeficiency virus in a multisite US Cohort, 2010–2016

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    Background. Retention in care (RIC) leads to reduced HIV transmission and mortality. Few studies have investigated clinic services and RIC among people living with HIV (PLWH) in the United States. We conducted a multisite retrospective cohort study to identify clinic services associated with RIC from 2010–2016 in the United States. Methods. PLWH with ≥1 HIV primary care visit from 2010–2016 at 7 sites in the Centers for AIDS Research Network of Integrated Clinical Systems (CNICS) were included. Clinic-level factors evaluated via site survey included patients per provider/ trainee, navigation, RIC posters/brochures, laboratory test timing, flexible scheduling, appointment reminder methods, and stigma support services. RIC was defined as ≥2 encounters per year, ≥90 days apart, observed until death, administrative censoring (31 December 2016), or loss to follow-up (censoring at first 12-month interval without a visit with no future visits). Poisson regression with robust error variance, clustered by site adjusting for calendar year, age, sex, race/ethnicity, and HIV transmission risk factor, estimated risk ratios (RRs) and 95% confidence intervals (CIs) for RIC. Results. Among 21 046 PLWH contributing 103 348 person-years, 67% of person-years were retained. Availability of text appointment reminders (RR, 1.13; 95% CI, 1.03–1.24) and stigma support services (RR, 1.11; 95% CI, 1.04–1.19) were associated with better RIC. Disparities persisted for age, sex, and race. Conclusions. Availability of text appointment reminders and stigma support services was associated with higher rates of RIC, indicating that these may be feasible and effective approaches for improving RIC

    Genome-wide association study of pancreatic fat: The multiethnic cohort adiposity phenotype study

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    Several studies have found associations between higher pancreatic fat content and adverse health outcomes, such as diabetes and the metabolic syndrome, but investigations into the genetic contributions to pancreatic fat are limited. This genome-wide association study, comprised of 804 participants with MRI-assessed pancreatic fat measurements, was conducted in the ethnically diverse Multiethnic Cohort-Adiposity Phenotype Study (MEC-APS). Two genetic variants reaching genome-wide significance, rs73449607 on chromosome 13q21.2 (Beta = -0.67, P = 4.50x10-8) and rs7996760 on chromosome 6q14 (Beta = -0.90, P = 4.91x10-8) were associated with percent pancreatic fat on the log scale. Rs73449607 was most common in the African American population (13%) and rs79967607 was most common in the European American population (6%). Rs73449607 was also associated with lower risk of type 2 diabetes (OR = 0.95, 95% CI = 0.89-1.00, P = 0.047) in the Population Architecture Genomics and Epidemiology (PAGE) Study and the DIAbetes Genetics Replication and Meta-analysis (DIAGRAM), which included substantial numbers of non-European ancestry participants (53,102 cases and 193,679 controls). Rs73449607 is located in an intergenic region between GSX1 and PLUTO, and rs79967607 is in intron 1 of EPM2A. PLUTO, a lncRNA, regulates transcription of an adjacent gene, PDX1, that controls beta-cell function in the mature pancreas, and EPM2A encodes the protein laforin, which plays a critical role in regulating glycogen production. If validated, these variants may suggest a genetic component for pancreatic fat and a common etiologic link between pancreatic fat and type 2 diabetes
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