Complex Relationships between Competing Guilds along Large-Scale Environmental Gradients

Despite much research over the past 30 years there is still little general understanding of how the outcomes of interactions vary along environmental gradients, particularly at large geographic scales. A simple expectation is that decreasing environmental quality should reduce densities of competitors and hence the effects of competition should weaken in poorer environments. A counter-intuitive consequence is that associations between densities of competitors might change from negative to positive as environments decrease in quality. Here we test these predictions in a set of vascular plant communities where perennial species share space and resources with less competitive annuals. We surveyed nine grey dune communities annually for 5 years along a cross-European latitudinal gradient of habitat quality. We find that densities of annual and perennial species are negatively correlated at the high-quality end of the gradient, while at the low-quality end guild densities are uncorrelated or positively correlated, consistent with a weakening of competition linked to increasing environmental limitations. Our results suggest that even simple interactions can give rise to non-obvious changes in species associations along environmental gradients. They highlight that understanding the outcome of species interactions may require explicit characterization of their changing intensity with environmental quality, and that the factors limiting species’ co-distribution can vary along environmental gradients

Etude de l'activité biologique de poudres industrielles fines et ultrafines de carbure de silicium : caractérisation physico-chimique.

National audienceL'industrie élabore et utilise des poudres de SiC de plus en plus fines. Depuis leur synthèse jusqu'à leur utilisation finale, les poudres subissent diverses opérations et traitements au cours desquels elles sont susceptibles de se disséminer dans l'atmosphère des locaux industriels, provoquant ainsi un risque d'inhalation. Les particules fines peuvent provoquer une réaction inflammatoire au niveau des poumons. L'objectif de cette étude est d'évaluer la toxicité et d'expliquer la réactivité biologique de différentes variétés de poudres industrielles de SiC

The Evolution of Functionally Redundant Species; Evidence from Beetles

While species fulfill many different roles in ecosystems, it has been suggested that numerous species might actually share the same function in a near neutral way. So-far, however, it is unclear whether such functional redundancy really exists. We scrutinize this question using extensive data on the world’s 4168 species of diving beetles. We show that across the globe these animals have evolved towards a small number of regularly-spaced body sizes, and that locally co-existing species are either very similar in size or differ by at least 35%. Surprisingly, intermediate size differences (10–20%) are rare. As body-size strongly reflects functional aspects such as the food that these generalist predators can eat, these beetles thus form relatively distinct groups of functional look-a-likes. The striking global regularity of these patterns support the idea that a self-organizing process drives such species-rich groups to self-organize evolutionary into clusters where functional redundancy ensures resilience through an insurance effect

Dual antibiotics for bronchiectasis

Background Bronchiectasis is a chronic respiratory disease characterised by abnormal and irreversible dilatation of the smaller airways and associated with a mortality rate greater than twice that of the general population. Antibiotics serve as front-line therapy for managing bacterial load, but their use is weighed against the development of antibiotic resistance. Dual antibiotic therapy has the potential to suppress infection from multiple strains of bacteria, leading to more successful treatment of exacerbations, reduced symptoms, and improved quality of life. Further evidence is required on the efficacy of dual antibiotics in terms of management of exacerbations and extent of antibiotic resistance. Objectives To evaluate the effects of dual antibiotics in the treatment of adults and children with bronchiectasis. Search methods We identified studies from the Cochrane Airways Group Specialised Register (CAGR), which includes the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Allied and Complementary Medicine (AMED), and PsycINFO, as well as studies obtained by handsearching of journals/abstracts. We also searched the following trial registries: US National Institutes of Health Ongoing Trials Register, ClinicalTrials.gov, and the World Health Organization (WHO) International Clinical Trials Registry Platform. We imposed no restriction on language of publication. We conducted our search in October 2017. Selection criteria We searched for randomised controlled trials comparing dual antibiotics versus a single antibiotic for short-term (< 4 weeks) or long-term management of bronchiectasis diagnosed in adults and/or children by bronchography, plain film chest radiography, or high-resolution computed tomography. Primary outcomes included exacerbations, length of hospitalisation, and serious adverse events. Secondary outcomes were response rates, emergence of resistance to antibiotics, systemic markers of infection, sputum volume and purulence, measures of lung function, adverse events/effects, deaths, exercise capacity, and health-related quality of life. We did not apply outcome measures as selection criteria. Data collection and analysis Two review authors independently screened the titles and abstracts of 287 records, along with the full text of seven reports. Two studies met review inclusion criteria. Two review authors independently extracted outcome data and assessed risk of bias. We extracted data from only one study and conducted GRADE assessments for the following outcomes: successful treatment of exacerbation; response rates; and serious adverse events. Main results Two randomised trials assessed the effectiveness of oral plus inhaled dual therapy versus oral monotherapy in a total of 118 adults with a mean age of 62.8 years. One multi-centre trial compared inhaled tobramycin plus oral ciprofloxacin versus ciprofloxacin alone, and one single-centre trial compared nebulised gentamicin plus systemic antibiotics versus a systemic antibiotic alone. Published papers did not report study funding sources. Effect estimates from one small study with 53 adults showed no evidence of treatment benefit with oral plus inhaled dual therapy for the following primary outcomes at the end of the study: successful management of exacerbation - cure at day 42 (odds ratio (OR) 0.66, 95% confidence interval (CI) 0.22 to 2.01; 53 participants; one study; very low-quality evidence); number of participants with Pseudomonas aeruginosa eradication at day 21 (OR 2.33, 95% CI 0.66 to 8.24; 53 participants; one study; very low-quality evidence); and serious adverse events (OR 0.48, 95% CI 0.08 to 2.87; 53 participants; one study; very low-quality evidence). Similarly, researchers provided no evidence of treatment benefit for the following secondary outcomes: clinical response rates - relapse at day 42 (OR 0.57, 95% CI 0.12 to 2.69; 53 participants; one study; very low-quality evidence); microbiological response rate at day 21 - eradicated (OR 2.40, 95% CI 0.67 to 8.65; 53 participants; one study; very low-quality evidence); and adverse events - incidence of wheeze (OR 5.75, 95% CI 1.55 to 21.33). Data show no evidence of benefit in terms of sputum volume, lung function, or antibiotic resistance. Outcomes from a second small study with 65 adults, available only as an abstract, were not included in the quantitative data synthesis. The included studies did not report our other primary outcomes: duration; frequency; and time to next exacerbation; nor our secondary outcomes: systemic markers of infection; exercise capacity; and quality of life. We did not identify any trials that included children. Authors' conclusions A small number of studies in adults have generated high-quality evidence that is insufficient to inform robust conclusions, and studies in children have provided no evidence. We identified only one dual-therapy combination of oral and inhaled antibiotics. Results from this single trial of 53 adults that we were able to include in the quantitative synthesis showed no evidence of treatment benefit with oral plus inhaled dual therapy in terms of successful treatment of exacerbations, serious adverse events, sputum volume, lung function, and antibiotic resistance. Further high-quality research is required to determine the efficacy and safety of other combinations of dual antibiotics for both adults and children with bronchiectasis, particularly in terms of antibiotic resistance

Raphaël Spina, Histoire du STO

L’ouvrage de Raphael Spina sur le Service du travail obligatoire (STO), issu d’une thèse soutenue en 2012 sous la direction d’Olivier Wieviorka, permet enfin de disposer d’une vision d’ensemble sur « l’inconnu le plus célèbre des années noires ». Non que le STO n’ait jamais été étudié : on disposait déjà de monographies locales et régionales (région lyonnaise, Lorraine…) et de la thèse du regretté Patrice Arnaud sur les requis en Allemagne. Mais il manquait une synthèse qui prenne en compte l..

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Functional, size and taxonomic diversity of fish along a depth gradient in the deep sea

Biodiversity is well studied in ecology and the concept has been developed to include traits of species, rather than solely taxonomy, to better reflect the functional diversity of a system. The deep sea provides a natural environmental gradient within which to study changes in different diversity metrics, but traits of deep-sea fish are not widely known, hampering the application of functional diversity to this globally important system. We used morphological traits to determine the functional richness and functional divergence of demersal fish assemblages along the continental slope in the Northeast Atlantic, at depths of 300–2,000 m. We compared these metrics to size diversity based on individual body size and species richness. Functional richness and size diversity showed similar patterns, with the highest diversity at intermediate depths; functional divergence showed the opposite pattern, with the highest values at the shallowest and deepest parts of the study site. Species richness increased with depth. The functional implications of these patterns were deduced by examining depth-related changes in morphological traits and the dominance of feeding guilds as illustrated by stable isotope analyses. The patterns in diversity and the variation in certain morphological traits can potentially be explained by changes in the relative dominance of pelagic and benthic feeding guilds. All measures of diversity examined here suggest that the deep areas of the continental slope may be equally or more diverse than assemblages just beyond the continental shelf