Tree-mediated methane emissions from tropical and temperate peatlands

Methane production and transport processes in peatlands are fairly well understood, but growing evidence for emission of methane through trees has highlighted the need to revisit methane transport processes. In wetland trees, morphological adaptations such as development of hypertrophied lenticels, aerenchyma and adventitious roots in response to soil anoxia mediates gas transport, transporting both oxygen from the atmosphere to oxygen-deprived roots and soil-produced methane from the root-zone to the atmosphere. Although, tree-mediated methane emissions from temperate tree species have been confirmed, methane emissions from tropical tree species and processes that control tree-mediated methane emissions remain unclear. This study explains the role of trees in transporting soil-produced methane to the atmosphere and uncovers the principal mechanisms of tree-mediated methane emissions. Methane emissions from eight tropical tree species and two temperate tree species were studied in situ. The mechanisms and controls on tree-mediated methane emissions were investigated using three year old common alder (Alnus glutinosa; 50 trees) grown under two artificially controlled water-table positions. Methane fluxes from whole mesocosms, the soil surface and tree stems were measured using static closed chambers. Both temperate and tropical tree species released significant quantities of methane, with tropical trees dominating ecosystem level methane fluxes. In temperate peatlands, both the methane gas transport mechanism and quantity of methane emitted from stems is tree-species dependent. In Alnus glutinosa, no correlations were observed between stomatal behaviour and tree-mediated methane emissions, however, stem methane emissions were positively correlated with both stem lenticel density and dissolved soil methane concentration. In Alnus glutinosa, no emissions were observed from leaf surfaces. The results demonstrate that exclusion of tree-mediated methane emissions from flux measurement campaigns in forested peatlands will lead to an underestimation of ecosystem-wide methane emissions

Gelsolin superfamily proteins: key regulators of cellular functions

Abstract.: Cytoskeletal rearrangement occurs in a variety of cellular processes and involves a wide spectrum of proteins. Among these, the gelsolin superfamily proteins control actin organization by severing filaments, capping filament ends and nucleating actin assembly [1]. Gelsolin is the founding member of this family, which now contains at least another six members: villin, adseverin, capG, advillin, supervillin and flightless I. In addition to their respective role in actin filament remodeling, these proteins have some specific and apparently non-overlapping particular roles in several cellular processes, including cell motility, control of apoptosis and regulation of phagocytosis (summarized in table 1). Evidence suggests that proteins belonging to the gelsolin superfamily may be involved in other processes, including gene expression regulation. This review will focus on some of the known functions of the gelsolin superfamily proteins, thus providing a basis for reflection on other possible and as yet incompletely understood roles for these protein

Turing learning: : A metric-free approach to inferring behavior and its application to swarms

We propose Turing Learning, a novel system identification method for inferring the behavior of natural or artificial systems. Turing Learning simultaneously optimizes two populations of computer programs, one representing models of the behavior of the system under investigation, and the other representing classifiers. By observing the behavior of the system as well as the behaviors produced by the models, two sets of data samples are obtained. The classifiers are rewarded for discriminating between these two sets, that is, for correctly categorizing data samples as either genuine or counterfeit. Conversely, the models are rewarded for 'tricking' the classifiers into categorizing their data samples as genuine. Unlike other methods for system identification, Turing Learning does not require predefined metrics to quantify the difference between the system and its models. We present two case studies with swarms of simulated robots and prove that the underlying behaviors cannot be inferred by a metric-based system identification method. By contrast, Turing Learning infers the behaviors with high accuracy. It also produces a useful by-product - the classifiers - that can be used to detect abnormal behavior in the swarm. Moreover, we show that Turing Learning also successfully infers the behavior of physical robot swarms. The results show that collective behaviors can be directly inferred from motion trajectories of individuals in the swarm, which may have significant implications for the study of animal collectives. Furthermore, Turing Learning could prove useful whenever a behavior is not easily characterizable using metrics, making it suitable for a wide range of applications.Comment: camera-ready versio

Reflexive learning, socio-cognitive conflict and peer-assessment to improve the quality of feedbacks in online tests

International audienceOur previous works have introduced the Tsaap-notes platform dedicated to the semi automatic generation of multiple choice questionnaire providing feedbacks: it reuses interactive questions asked by teachers during lectures, as well as the notes taken by students after the presentation of the results as feedbacks integrated into the quizzes. In this paper, we introduce a new feature which aims at increasing the number of contributions of students in order to significantly improve the quality of the feedbacks used in the resulting quizzes. This feature splits the submission of an answer into several distinct phases to harvest explanations given by students, and then applies an algorithm to filter the best contributions to be integrated as feedbacks in the tests. Our approach has been validated by a first experimentation involving master students enrolled in a computer science course

Methylphenidate for attention-deficit/hyperactivity disorder in children and adolescents: Cochrane systematic review with meta-analyses and trial sequential analyses of randomised clinical trials

Study question: Is methylphenidate beneficial or harmful for the treatment of attention-deficit/hyperactivity disorder (ADHD) in children and adolescents? / Methods: Electronic databases were searched up to February 2015 for parallel and crossover randomised clinical trials comparing methylphenidate with placebo or no intervention in children and adolescents with ADHD. Meta-analyses and trial sequential analyses (TSA) were conducted. Quality was assessed using GRADE. Teachers, parents, and observers rated ADHD symptoms and general behaviour. / Study answer and limitations: The analyses included 38 parallel group trials (n=5111, median treatment duration 49 days) and 147 crossover trials (n=7134, 14 days). The average age across all studies was 9.7 years. The analysis suggested a beneficial effect of methylphenidate on teacher rated symptoms in 19 parallel group trials (standardised mean difference (SMD) −0.77, n=1698), corresponding to a mean difference of −9.6 points on the ADHD rating scale. There was no evidence that methylphenidate was associated with an increase in serious adverse events (risk ratio 0.98, nine trials, n=1532; TSA adjusted intervention effect RR 0.91). Methylphenidate was associated with an increased risk of non-serious adverse events (1.29, 21 trials, n=3132; TSA adjusted RR 1.29). Teacher rated general behaviour seemed to improve with methylphenidate (SMD −0.87, five trials, n=668) A change of 7 points on the child health questionnaire (CHQ) has been deemed a minimal clinically relevant difference. The change reported in a meta-analysis of three trials corresponds to a mean difference of 8.0 points on the CHQ (range 0-100 points), which suggests that methylphenidate may improve parent reported quality of life (SMD 0.61, three trials, n=514). 96.8% of trials were considered high risk of bias trials according to the Cochrane guidelines. All outcomes were assessed very low quality according to GRADE. / What this study adds: The results suggest that among children and adolescents with a diagnosis of ADHD, methylphenidate may improve teacher reported symptoms of ADHD and general behaviour and parent reported quality of life. However, given the risk of bias in the included studies, and the very low quality of outcomes, the magnitude of the effects is uncertain. Methylphenidate is associated with an increased risk of non-serious but not serious adverse events. / Funding, competing interests, data sharing: Region Zealand Research Foundation and Copenhagen Trial Unit. Competing interests are given in the full paper on bmj.com. Full data are available in the version of this review published in The Cochrane Library

Large emissions from floodplain trees close the Amazon methane budget

Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests6 and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ13C) of −66.2 ± 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 ± 1.8 to 21.2 ± 2.5 teragrams of CH4 a year, in addition to the 20.5 ± 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a ‘top-down’ regional estimate of CH4 emissions of 42.7 ± 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010–2013. We find close agreement between our ‘top-down’ and combined ‘bottom-up’ estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources

Assessing inter-beach differences in semi-terrestrial arthropod assemblages on Maltese pocket sandy beaches (Central Mediterranean)

The distinctiveness of macrofaunal assemblages on different sandy beaches in the Maltese Islands was previously suggested by different single-season studies. A multi-seasonal sampling programme using pitfall trapping was implemented on four Maltese beaches to test the occurrence of this phenomenon. A total of 29,302 individuals belonging to 191 species were collected over a 2-year period, during which the beaches were sampled once per calendar season. A total of 77 species were recorded from single Maltese beaches only, of which nine were psammophiles. Non-metric multidimensional scaling analyses of pitfall trap species-abundance data resulted in a weak separation pattern, with samples grouping mainly in terms of beach and island rather than in terms of season or year of sampling, No physical variable could conclusively explain these patterns. It is concluded that although operating on Maltese beaches, macrofaunal assemblage distinctiveness is weaker than originally thought and can be attributed to the presence/absence or abundance of just a few psammophilic species. It is postulated that this phenomenon may be related to the ‘pocket beach’ nature of Maltese beaches, where headlands on either side of the beach to a large extent prevent the occurrence of longshore currents, resulting in semi-isolation of the populations of psammophilic species. A large number of single-beach records reported in this study highlight the high degree of beta diversity and spatial heterogeneity of Maltese beaches, and the conservation importance of the individual beach macrofaunal assemblages.peer-reviewe

controlling the disease

Surveillance and outbreak reports Surveillance of extensively drug-resistant tuberculosis in Europe, 2003-2007 15 by I Devaux, D Manissero, K Fernandez de la Hoz, K Kremer, D van Soolingen, on behalf of the EuroTB network Analysis of tuberculosis treatment outcomes in the European Union and European Economic Area: efforts needed towards optimal case management and control 21 by D Manissero, V Hollo, E Huitric, C Ködmön, A Amato-Gauci Risk of developing tuberculosis from a school contact: retrospective cohort study

Photosynthetic Limitation as a Factor Influencing Yield in Highbush Blueberries (<i>Vaccinium Corymbosum</i>) Grown in a Northern European Environment

Published evidence indicates that nearly 60% of blueberry-producing countries experience yield instability. Yield is a complex trait determined by genetic and environmental factors. Here, using physiological and biochemical approaches, we tested the hypothesis that yield instability results from year-to-year environmental variation that limits carbon assimilation, storage and partitioning. The data indicate that fruit development depends primarily on the daily production of non-structural carbohydrates by leaves, and there is no accumulation of a starch buffer to allow continuous ripening under conditions limiting for photosynthesis. Photosynthesis was saturated at moderate light irradiance and this was mainly due to stomatal and biochemical limitations. In a dynamic light environment, photosynthesis was further limited by slow stomatal response to increasing light. Finally, labelling with 13 CO 2 at specific stages of fruit development revealed a relatively even distribution of newly assimilated carbon between stems, roots and fruits, suggesting that the fruit is not a strong sink. We conclude that a significant component of yield variability results from limitations in photosynthetic efficiency that are compounded by an inability to accumulate starch reserves in blueberry storage tissues in a typical northern European environment. This work informs techniques for improving agronomic management and indicates key traits required for yield stability in such environments.</p

Role of regional wetland emissions in atmospheric methane variability

Atmospheric methane (CH4) accounts for ~20% of the total direct anthropogenic radiative forcing by long-lived greenhouse gases. Surface observations show a pause (1999-2006) followed by a resumption in CH4 growth, which remain largely unexplained. Using a land surface model, we estimate wetland CH4 emissions from 1993 to 2014 and study the regional contributions to changes in atmospheric CH4. Atmospheric model simulations using these emissions, together with other sources, compare well with surface and satellite CH4 data. Modelled global wetland emissions vary by ±3%/yr (σ=4.8 Tg), mainly due to precipitation-induced changes in wetland area, but the integrated effect makes only a small contribution to the pause in CH4 growth from 1999 to 2006. Increasing temperature, which increases wetland area, drives a long-term trend in wetland CH4 emissions of +0.2%/yr (1999 to 2014). The increased growth post-2006 was partly caused by increased wetland emissions (+3%), mainly from Tropical Asia, Sourthern Africa and Australia