1,456 research outputs found

    Game of tops: trends in GBIFs community of users

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    Building on the development of Biodiversity Informatics, the Global Biodiversity Information Facility (GBIF) undertook the task of enabling access to the world¿s wealth of biodiversity data via the Internet. To date, GBIF has become, in many respects, the most extensive biodiversity information exchange infrastructure in the world, opening up a full range of possibilities for science

    Does low-dose aspirin initiated before 11 weeks' gestation reduce the rate of preeclampsia?

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    OBJECTIVE: DATA: Pre-conception or early administration of low-dose aspirin might improve endometrial growth, placental vascularization and organogenesis. Most studies have evaluated the potential benefit of pre-conception or early administration of low-dose aspirin in women with a history of recurrent pregnancy loss, women who have undergone in vitro fertilization or women with thrombophilia or antiphospholipid syndrome. These women are at an increased risk of placenta-associated complications of pregnancy, including preeclampsia, preterm delivery and fetal growth restriction. STUDY: We performed a systematic review and meta-analysis to evaluate the effect of low-dose aspirin initiated at <11 weeks' gestation on the risk of preeclampsia, gestational hypertension, or any hypertensive disorder of pregnancy. Secondary outcomes included preterm delivery at <37 weeks' gestation and fetal growth restriction. STUDY APPRAISAL AND SYNTHESIS METHODS: We searched in MEDLINE via PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.Gov and the World Health Organization International Clinical Trials Registry Platform (WHO-ICTRP) from 1985 to November 2018. Entry criteria were randomized controlled trials evaluating the effect of aspirin administered at 85% of the study population. Relative risks (RR) with 95% confidence intervals (CI) were calculated for each study and pooled for global analysis as the effect measure. We assessed statistical heterogeneity in each meta-analysis using the Chi2 statistics, I2 and Tau2. Heterogeneity was considered substantial if an I2 was greater than 50% and either the Tau2 was greater than zero, or there was a low P-value (<0.10) in the Chi2 test for heterogeneity. Random-effects meta-analysis, weighted by the size of the studies, was performed to produce an overall summary on aspirin effect for each outcome. Sensitivity analysis by sequential omission of each individual study and by fixed-effects model was performed. Publication bias was not assessed due to the small number of included studies. Statistical analysis was performed using Stata release 14.0 (StataCorp, College Station, TX). RESULTS: The entry criteria were fulfilled by eight randomized controlled trials on a combined total of 1,426 participants. Low-dose aspirin initiated at <11 weeks' gestation was associated with a non-significant reduction in the risk of preeclampsia (RR 0.52; 95% CI: 0.23-1.17, P=0.115), gestational hypertension (RR 0.49; 95% CI: 0.20-1.21; P=0.121) and any hypertensive disorder of pregnancy (RR 0.59; 95% CI 0.33-1.04, P=0.067). Early low-dose aspirin reduced the risk of preterm delivery (RR 0.52; 95% CI: 0.27-0.97, p=0.040) but had no impact on the risk of fetal growth restriction (RR 1.10; 95% CI 0.58-2.07, P=0.775). Except for preterm delivery and any hypertensive disorder of pregnancy, sensitivity analysis demonstrated similar observations; therefore confirming the robustness of the analysis. CONCLUSION: The administration of low-dose aspirin at <11 weeks' gestation in high risk women does not decrease the risk of preeclampsia, gestational hypertension, any hypertensive disorder of pregnancy and fetal growth restriction. However, it might reduce the risk of preterm delivery. Larger randomized controlled trials will be required to substantiate the findings.pre-print408 K

    Patología endodóntica periodontal. Revisión bibliográfica

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    Los procesos patológicos que afectan a las estructuras del periodonto pueden tener diversos orígenes y cursar con una sintomatología parecida. No hay signos ni síntomas patognomónicos que nos indiquen una etiología concreta. Por tanto, es preciso utilizar todas las pruebas diagnósticas disponibles para descubrir el origen de la afectación, e instaurar el tratamiento apropiado, Sólo así se evitarán fracasos diagnósticos y terapéuticos. En este trabajo se revisan las comunicaciones existentes entre la pulpa y el periodonto, la patogenia de las lesiones endoperiodontales, su pronóstico, su tratamiento y se hace especial hincapié en el diagnóstico y diagnóstico diferencial de dichas lesiones

    A Series of Manganese(III) Salen Complexes as a Result of Team-Based Inquiry in a Transnational Education Programme.

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    The development of a team-based approach to research-led transnational practical chemistry teaching is described in which a team of five Chinese students on an articulated transnational degree programme, supported by a team of academic and technical staff, carried out a study examining the structural chemistry of a series of manganese(III) salen complexes. A series of four crystallographically characterized manganese(III) salen complexes with ancillary carboxylate ligands are reported here. The carboxylate coordination modes range from the bridging syn-anti μ2 -κO : κO' mode observed in the predominant cyclohexanoate and isobutyrate species, to a capping terminal monodentate mode for the adamantanoate species, and an unusual mixture of bridging and terminal coordination modes observed in a second minor phase of the cyclohexanoate species. The variation on extended structures based on the weakly interacting aliphatic backbones may provide a useful basis for further structural studies

    Meta-DiSc 2.0:a web application for meta-analysis of diagnostic test accuracy data

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    BACKGROUND: Diagnostic evidence of the accuracy of a test for identifying a target condition of interest can be estimated using systematic approaches following standardized methodologies. Statistical methods for the meta-analysis of diagnostic test accuracy (DTA) studies are relatively complex, presenting a challenge for reviewers without extensive statistical expertise. In 2006, we developed Meta-DiSc, a free user-friendly software to perform test accuracy meta-analysis. This statistical program is now widely used for performing DTA meta-analyses. We aimed to build a new version of the Meta-DiSc software to include statistical methods based on hierarchical models and an enhanced web-based interface to improve user experience. RESULTS: In this article, we present the updated version, Meta-DiSc 2.0, a web-based application developed using the R Shiny package. This new version implements recommended state-of-the-art statistical models to overcome the limitations of the statistical approaches included in the previous version. Meta-DiSc 2.0 performs statistical analyses of DTA reviews using a bivariate random effects model. The application offers a thorough analysis of heterogeneity, calculating logit variance estimates of sensitivity and specificity, the bivariate I-squared, the area of the 95% prediction ellipse, and the median odds ratios for sensitivity and specificity, and facilitating subgroup and meta-regression analyses. Furthermore, univariate random effects models can be applied to meta-analyses with few studies or with non-convergent bivariate models. The application interface has an intuitive design set out in four main menus: file upload; graphical description (forest and ROC plane plots); meta-analysis (pooling of sensitivity and specificity, estimation of likelihood ratios and diagnostic odds ratio, sROC curve); and summary of findings (impact of test through downstream consequences in a hypothetical population with a given prevalence). All computational algorithms have been validated in several real datasets by comparing results obtained with STATA/SAS and MetaDTA packages. CONCLUSION: We have developed and validated an updated version of the Meta-DiSc software that is more accessible and statistically sound. The web application is freely available at www.metadisc.es

    Comparative efficacy between atorvastatin and rosuvastatin in the prevention of cardiovascular disease recurrence

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    Background: There is no randomized clinical trials with recurrence of atherosclerotic cardiovascular disease (ASCVD) as a major outcome with rosuvastatin. In order to analyze potential differences in the clinical response to atorvastatin and rosuvastatin in secondary ASCVD prevention, we have analyzed the clinical evolution of those subjects of the Dyslipemia Registry of the Spanish Society of Arteriosclerosis (SEA) who at the time of inclusion in the Registry had already suffered an ASCVD. Methods: This observational, retrospective, multicenter, national study was designed to determine potential differences between the use of atorvastatin and rosuvastatin in the ASCVD recurrence. Three different follow-up start-times were performed: time of inclusion in the registry; time of first event if this occurred after 2005, and time of first event without date restriction. Results: Baseline characteristics were similar between treatment groups. Among atorvastatin or rosuvastatin users, 89 recurrences of ASCVD were recorded (21.9%), of which 85.4% were coronary. At the inclusion of the subject in the registry, 345 participants had not suffered a recurrence yet. These 345 subjects accumulated 1050 person-years in a mean follow-up of 3 years. Event rates were 2.73 (95% CI: 1.63, 4.25) cases/100 person-years and 2.34 (95% CI: 1.17, 4.10) cases/100 person-years in the atorvastatin and rosuvastatin groups, respectively. There were no statistically significant differences between the two groups independently of the follow-up start-time. Conclusions: This study does not find differences between high doses of rosuvastatin and atorvastatin in the recurrence of ASCVD, and supports their use as clinically equivalent in secondary prevention of ASCVD

    The tragedy of the biodiversity data commons: a data impediment creeping nigher?

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    Researchers are embracing the open access movement to facilitate unrestricted availability of scientific results. One sign of this willingness is the steady increase in data freely shared online, which has prompted a corresponding increase in the number of papers using such data. Publishing datasets is a time-consuming process that is often seen as a courtesy, rather than a necessary step in the research process. Making data accessible allows further research, provides basic information for decision-making and contributes to transparency in science. Nevertheless, the ease of access to heaps of data carries a perception of `free lunch for all¿, and the work of data publishers is largely going unnoticed. Acknowledging such a significant effort involving the creation, management and publication of a dataset remains a flimsy, not well established practice in the scientific community. In a meta-analysis of published literature, we have observed various dataset citation practices, but mostly (92%) consisting of merely citing the data repository rather than the data publisher. Failing to recognize the work of data publishers might lead to a decrease in the number of quality datasets shared online, compromising potential research that is dependent on the availability of such data. We make an urgent appeal to raise awareness about this issue

    Completeness of Digital Accessible Knowledge (DAK) about terrestrial mammals in the Iberian Peninsula

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    The advent of online data aggregator infrastructures has facilitated the accumulation of Digital Accessible Knowledge (DAK) about biodiversity. Despite the vast amount of freely available data records, their usefulness for research depends on completeness of each body of data regarding their spatial, temporal and taxonomic coverage. In this paper, we assess the completeness of DAK about terrestrial mammals distributed across the Iberian Peninsula. We compiled a dataset with all records about mammals occurring in the Iberian Peninsula available in the Global Biodiversity Information Facility and in the national atlases from Portugal and Spain. After cleaning the dataset of errors as well as records lacking collection dates or not determined to species level, we assigned all occurrences to a 10-km grid. We assessed inventory completeness by calculating the ratio between observed and expected richness (based on the Chao2 richness index) in each grid cell and classified cells as well-sampled or under-sampled. We evaluated survey coverage of well-sampled cells along four environmental gradients and temporal coverage. Out of 796,283 retrieved records, quality issues led us to remove 616,141 records unfit for this use. The main reason for discarding records was missing collection dates. Only 25.95% cells contained enough records to robustly estimate completeness. The DAK about terrestrial mammals from the Iberian Peninsula was low, and spatially and temporally biased
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