Increased soil temperature and atmospheric N deposition have no effect on the N status and growth of a mature balsam fir forest

Nitrogen (N) is a major growth-limiting factor in boreal forest ecosystems. Increases of temperature and atmospheric N deposition are expected to affect forest growth directly and indirectly by increasing N availability due to higher rates of N mineralization. In order to understand the potential impacts of these changes, a mature balsam fir stand in Québec, Canada, was subjected during three consecutive growing seasons (2009-2011) to (i) experimentally increased soil temperature (4 C) and earlier snowmelt (2-3 weeks) as well as (ii) increased inorganic N concentration in artificial precipitation (3 × current N concentrations using 15NH4-15NO3). Soil inorganic N was measured using buried ion-exchange membranes (PRS™ probes) and standard soil extractions. Dendrometers were used to monitor the variations in diameter growth and needles were analyzed annually for N to assess the nutritional response of trees. Results from the second (2010) and third (2011) year of treatment are reported. After three years of treatment, there was no significant increase in soil nitrate (NO3) or ammonium (NH4) availability either in the organic or in the mineral soil as measured with standard soil extractions. Similar results were obtained with ion-exchange membranes, except for NH4 in the forest floor, which increased by an average of 54% over the two years. No effect of treatments were observed on needle N or diameter growth, but an 8-day earlier peak in diameter growth was measured in heated plots in 2010. We attributed the limited effects of our treatments to the acute soil competition for available N at the site. As a result, the projected modifications of the forest N cycle and concomitant increased forest growth due to an earlier snowmelt, increased soil temperature and N deposition should be considered with caution in similar cold N-poor ecosystems

A tablet-based quantitative assessment of manual dexterity for detection of early psychosis

BackgroundWe performed a pilot study on whether tablet-based measures of manual dexterity can provide behavioral markers for detection of first-episode psychosis (FEP), and whether cortical excitability/inhibition was altered in FEP.MethodsBehavioral and neurophysiological testing was undertaken in persons diagnosed with FEP (N = 20), schizophrenia (SCZ, N = 20), autism spectrum disorder (ASD, N = 20), and in healthy control subjects (N = 20). Five tablet tasks assessed different motor and cognitive functions: Finger Recognition for effector (finger) selection and mental rotation, Rhythm Tapping for temporal control, Sequence Tapping for control/memorization of motor sequences, Multi Finger Tapping for finger individuation, and Line Tracking for visuomotor control. Discrimination of FEP (from other groups) based on tablet-based measures was compared to discrimination through clinical neurological soft signs (NSS). Cortical excitability/inhibition, and cerebellar brain inhibition were assessed with transcranial magnetic stimulation.ResultsCompared to controls, FEP patients showed slower reaction times and higher errors in Finger Recognition, and more variability in Rhythm Tapping. Variability in Rhythm Tapping showed highest specificity for the identification of FEP patients compared to all other groups (FEP vs. ASD/SCZ/Controls; 75% sensitivity, 90% specificity, AUC = 0.83) compared to clinical NSS (95% sensitivity, 22% specificity, AUC = 0.49). Random Forest analysis confirmed FEP discrimination vs. other groups based on dexterity variables (100% sensitivity, 85% specificity, balanced accuracy = 92%). The FEP group had reduced short-latency intra-cortical inhibition (but similar excitability) compared to controls, SCZ, and ASD. Cerebellar inhibition showed a non-significant tendency to be weaker in FEP.ConclusionFEP patients show a distinctive pattern of dexterity impairments and weaker cortical inhibition. Easy-to-use tablet-based measures of manual dexterity capture neurological deficits in FEP and are promising markers for detection of FEP in clinical practice

Regards croisés sur la méthodologie de l'écrit 1. De l'intérêt du compte-rendu de lecture

Aux concours du CAPEPS et de l'Agrégation d'EPS, la première épreuve écrite d'admissibilité consiste en une dissertation portant sur les fondements sociohistoriques et épistémologiques de l'éducation physique et sportive. Les rapports de jury insistent sur la nécessité d'adopter une démarche critique et engagée. Ils déplorent, en revanche, des difficultés d'ordre méthodologique dans l'usage de la citation mise en exergue des sujets. Ce double constat interroge les pratiques en formation. Entremêlant les points de vue d'un formateur et d'un étudiant admis à la dernière session de l'Agrégation, cet article propose de discuter l'intérêt du compte-rendu de lecture, avec la volonté d'en démêler les apports et limites au plan méthodologique, scientifique, professionnel et personnel. Plus largement, il s'agit de mettre en débat la place de la lecture et de l'écriture, synthétique et distanciée, dans les formations en STAPS

Traitement des leishmanioses viscérales et cutanées par la miltéfosine

Transmises par la piqûre d'un insecte vecteur, le phlébotome femelle. les leishmanioses (viscérales, cutanéo-muqueuses et cutanées) sont un groupe de maladies parasitaires, répandues dans le monde entier et ayant des conséquences très graves, dues à l'infection par différentes espèces de protozoaires flagellés appartenant au genre Leishmania. Bien que beaucoup de personnes soient souvent piquées par les phlébotomes infectés par des leishmanies, la plupart ne développe pas la maladie. Toutefois, en cas d'immuno-dépression sévère, il y a évolution rapide vers le tableau complet de la maladie. La miltéfosine, développée à l'origine comme une molécule anticancéreuse, semble être très efficace per os suite à des études sur des modèles animaux atteints de leishmaniose viscérale et cutanée. La durée de traitement recommandée de la leishmaniose viscérale est de quatre semaines à des doses de 100 mg/jour pour les personnes de plus de 25 kg et de 50 mg/jour pour les personnes de moins de 25 kg. A ces doses, plus de 95% des patients sont guéris qu'ils soient immuno-compétents ou immuno-déprimés. La durée de traitement recommandée de la leishmaniose cutanée est de trois à quatre semaines à des doses de 2.25 mg/kg/jour. Ainsi, la miltéfosine, molécule tératogène dont les effets secondaires sont essentiellement de type gastro-intestinaux, aurait le potentiel de devenir la première molécule hautement efficace per os dans le traitement de ces maladies parasitaires menaçantes. La perspective d'avoir une molécule administrée par voie orale plutôt que parentérale est, en effet, une bonne nouvelle, ceci, contribuant à faciliter et à améliorer l'observance du traitement des patients atteints de la maladie. Néanmoins, la miltéfosine ne possède encore, à ce jour, aucune Autorisation de Mise sur le Marché pour le traitement de la leishmaniose viscérale et cutanée.ROUEN-BU Médecine-Pharmacie (765402102) / SudocSudocFranceF

DROGUES ET SECURITE ROUTIERE

RENNES1-BU Santé (352382103) / SudocSudocFranceF

The effects of throughfall exclusion on xylogenesis of balsam fir

A 20-40% reduction in soil moisture is projected for the boreal forest of Eastern Canada for the period 2070-99 relative to 1971-2000. In order to better predict the effects of a reduced water supply on the growth of balsam fir (Abies balsamea (L.) Mill.), a dominant tree species of the boreal forest, we simulated 2 consecutive years of summer droughts (starting in July) by means of throughfall exclusion. Four 100-m2 plots were established in 2010 with polyethylene sheets maintained 1.3-2 m aboveground and redirecting the water outside the plots. Wood microcores were extracted weekly from mature trees from April to October 2011 to analyse the time dynamics of wood formation in that year. The number of tracheids formed during and before treatment and their anatomical characteristics were determined through microscopic analyses. The growth of lateral and terminal branches and the water potential of balsam fir seedlings were also monitored. Throughfall exclusion significantly reduced soil water content by 5.8% in 2010 and 10.5% in 2011. Xylogenesis was affected significantly by the treatment. Tracheids were 16.1% smaller in diameter and their cell wall was 14.1% thicker during both years. The treatment delayed by more than a week the start of the tracheid differentiation process in the second year with a concomitant decrease (26%) in the number of tracheids produced. The seedlings displayed a 32% reduction in growth and a 40% reduction in leaf water potential. Our results suggest that a future regime of increased frequency and intensity of droughts could have negative effects on the duration of xylogenesis and the production of xylem cells in balsam fir

Pyrosequencing assessment of prokaryotic and eukaryotic diversity in biofilm communities from a French river.

International audienceDespite the recent and significant increase in the study of aquatic microbial communities, little is known about the microbial diversity of complex ecosystems such as running waters. This study investigated the biodiversity of biofilm communities formed in a river with 454 Sequencing™. This river has the particularity of integrating both organic and microbiological pollution, as receiver of agricultural pollution in its upstream catchment area and urban pollution through discharges of the wastewater treatment plant of the town of Billom. Different regions of the small subunit (SSU) ribosomal RNA gene were targeted using nine pairs of primers, either universal or specific for bacteria, eukarya, or archaea. Our aim was to characterize the widest range of rDNA sequences using different sets of polymerase chain reaction (PCR) primers. A first look at reads abundance revealed that a large majority (47-48%) were rare sequences (<5 copies). Prokaryotic phyla represented the species richness, and eukaryotic phyla accounted for a small part. Among the prokaryotic phyla, Proteobacteria (beta and alpha) predominated, followed by Bacteroidetes together with a large number of nonaffiliated bacterial sequences. Bacillariophyta plastids were abundant. The remaining bacterial phyla, Verrucomicrobia and Cyanobacteria, made up the rest of the bulk biodiversity. The most abundant eukaryotic phyla were annelid worms, followed by Diatoms, and Chlorophytes. These latter phyla attest to the abundance of plastids and the importance of photosynthetic activity for the biofilm. These findings highlight the existence and plasticity of multiple trophic levels within these complex biological systems

A three-year increase in soil temperature and atmospheric N deposition has minor effects on the xylogenesis of mature balsam fir

Tree growth in most boreal forests is strongly regulated by temperature and nitrogen (N) availability. The expected increases in soil temperature and N deposition over the next decades have the potential to affect the phenology of tree growth and xylogenesis. To test for these changes on xylogenesis of balsam fir (Abies balsamea (L.) Mill), 12 mature trees were subjected to a combination of experimentally increased soil temperature (+4 °C) with an earlier snowmelt (2-3 weeks) and N deposition (3 × ambient rain N concentrations using NH4-NO3 in artificial precipitation) over a 3-year period. Increased soil temperature and atmospheric N deposition had no significant effect on the number of tracheids produced (38-51), tracheid diameter (27.2-29.0 μm) and cell wall thickness (2.5-3.1 μm). For the 3 years of treatment, xylogenesis was initiated at minimum and average daily air temperatures of 0.6 ± 0.5 and 6.5 ± 0.6 °C, respectively, with inter-annual differences of 17 days in the onset of xylogenesis. The earlier snowmelt induced by soil warming did not hasten resumption of xylogenesis, and the time dynamics of xylogenesis was not affected by higher N deposition. Our results suggest that soil temperature and the timing of snowmelt have no direct influence on the breaking of cambium dormancy in balsam fir. The short-term effects of increased soil temperature and N deposition on xylogenesis of mature balsam fir appear to be small compared with the effects of air temperature and are likely to be associated with a persistent N limitation