Nitrous oxide fluxes and nitrogen cycling along a pasture chronosequence in Central Amazonia, Brazil

International audienceWe studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarém, Pará, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N2O we measured 27 soil chemical, soil microbiological and soil physical variables. Soil N2O fluxes were higher in the wet season than in the dry season. Fluxes of N2O from forest soils always exceeded fluxes from pasture soils and showed no consistent trend with pasture age. At our forest sites, nitrate was the dominant form of inorganic N both during wet and dry season. At our pasture sites nitrate generally dominated the inorganic N pools during the wet season and ammonium dominated during the dry season. Net mineralization and nitrification rates displayed large variations. During the dry season net immobilization of N was observed in some pastures. Compared to forest sites, young pasture sites (?2 years) had low microbial biomass N and protease activities. Protease activity and microbial biomass N peaked in pastures of intermediate age (4 to 8 years) followed by consistently lower values in older pasture (10 to 60 years). The C/N ratio of litter was low at the forest sites (~25) and rapidly increased with pasture age reaching values of 60-70 at pastures of 15 years and older. Nitrous oxide emissions at our sites were controlled by C and N availability and soil aeration. Fluxes of N2O were negatively correlated to leaf litter C/N ratio, NH4+-N and the ratio of NO3--N to the sum of NO3--N + NH4+-N (indicators of N availability), and methane fluxes and bulk density (indicators of soil aeration status) during the wet season. During the dry season fluxes of N2O were positively correlated to microbial biomass N, ?-glucosidase activity, total inorganic N stocks and NH4+-N. In our study region, pastures of all age emitted less N2O than old-growth forests, because of a progressive decline in N availability with pasture age combined with strongly anaerobic conditions in some pastures during the wet season

Inventory Existing Risk Scenarios

This report provides an inventory of existing hazard data, spatial data sets and socioeconomic projections to process scenario information and future risk projections for the ENHANCE case studies. As a basis for this inventory, we conducted a small survey across the EHNHANCE cases study on their data needs. Table 1.1 provides a preliminary overview of the hazard- and socioeconomic data and scenario's required within the different case studies. This overview on the case study data needs and the data availability within the different case study partners, was discussed during the project meetings in Venice, May 2013 and Ispra (September 2013). During the meeting in Ispra, the case studies were offered a 2 days hands on workshop on how to use scenario and risk data or their case studies. This workshop was offered by IVM and JRC. Since the ENHANCE project follows a risk based approach, we similarly have focused this report on (1) data and projections for different types of natural hazards (Chapter 2) and (2) trends in socioeconomic factors that influence exposure and vulnerability to the natural hazard (Chapter 3). In addition, we have specifically outlined methods to process socioeconomic scenarios (Chapter 4) and probabilistic methods (Chapter 5) to describe extreme events with a very low probability. The main objectives of this report are to: - Provide an inventory of dynamic hazard scenarios at the pan-European scale, based on existing information at JRC or other institutes; - Provide an inventory of socioeconomic data and projections in Europe as well as some global outlook projections, possibly relevant for ENHANCE; - Develop a probabilistic risk framework for identifying probabilities of extreme events in the case studies

Chronic nitrogen addition causes a reduction in soil carbon dioxide efflux during the high stem-growth period in a tropical montane forest but no response from a tropical lowland forest on a decadal time scale

Atmospheric nitrogen (N) deposition is rapidly increasing in tropical regions. We studied the response of soil carbon dioxide (CO<sub>2</sub>) efflux to long-term experimental N addition (125 kg N ha<sup>−1</sup> yr<sup>−1</sup>) in mature lowland and montane forests in Panama. In the lowland forest, on soils with high nutrient-supplying and buffering capacity, fine litterfall and stem-growth were neither N- nor phosphorus-limited. In the montane forest, on soils with low nutrient supplying capacity and an organic layer, fine litterfall and stem-growth were N-limited. Our objectives were to 1) explore the influence of soil temperature and moisture on the dynamics of soil CO<sub>2</sub> efflux and 2) determine the responses of soil CO<sub>2</sub> efflux from an N-rich and N-limited forest to elevated N input. Annual soil CO<sub>2</sub>-C efflux was larger in the lowland (15.44 ± 1.02 Mg C ha<sup>−1</sup>) than in the montane forest (9.37 ± 0.28 Mg C ha<sup>−1</sup>). In the lowland forest, soil moisture explained the largest fraction of the variance in soil CO<sub>2</sub> efflux while soil temperature was the main explanatory variable in the montane forest. Soil CO<sub>2</sub> efflux in the lowland forest did not differ between the control and 9–11 yr N-addition plots, suggesting that chronic N input to nutrient-rich tropical lowland forests on well-buffered soils may not change their C balance on a decadal time scale. In the montane forest, first year N addition did not affect soil CO<sub>2</sub> efflux but annual CO<sub>2</sub> efflux was reduced by 14% and 8% in the 2nd and 3rd year N-addition plots, respectively, compared to the control. This reduction was caused by a decrease in soil CO<sub>2</sub> efflux during the high stem-growth period of the year, suggesting a shift in carbon partitioning from below- to aboveground in the N-addition plots in which stem diameter growth was promoted

Measuring Patient-Reported Outcomes Adaptively: Multidimensionality Matters!

As there is currently a marked increase in the use of both unidimensional (UCAT) and multidimensional computerized adaptive testing (MCAT) in psychological and health measurement, the main aim of the present study is to assess the incremental value of using MCAT rather than separate UCATs for each dimension. Simulations are based on empirical data that could be considered typical for health measurement: a large number of dimensions (4), strong correlations among dimensions (.77-.87), and polytomously scored response data. Both variable- (SE <.316, SE <.387) and fixed-length conditions (total test length of 12, 20, or 32 items) are studied. The item parameters and variance–covariance matrix Φ are estimated with the multidimensional graded response model (GRM). Outcome variables include computerized adaptive test (CAT) length, root mean square error (RMSE), and bias. Both simulated and empirical latent trait distributions are used to sample vectors of true scores. MCATs were generally more efficient (in terms of test length) and more accurate (in terms of RMSE) than their UCAT counterparts. Absolute average bias was highest for variable-length UCATs with termination rule SE <.387. Test length of variable-length MCATs was on average 20% to 25% shorter than test length across separate UCATs. This study showed that there are clear advantages of using MCAT rather than UCAT in a setting typical for health measurement

Analysis of the Emails From the Dutch Web-Based Intervention “Alcohol de Baas”:Assessment of Early Indications of Drop-Out in an Online Alcohol Abuse Intervention

Nowadays, traditional forms of psychotherapy are increasingly complemented by online interactions between client and counselor. In (some) web-based psychotherapeutic interventions, meetings are exclusively online through asynchronous messages. As the active ingredients of therapy are included in the exchange of several emails, this verbal exchange contains a wealth of information about the psychotherapeutic change process. Unfortunately, drop-out-related issues are exacerbated online. We employed several machine learning models to find (early) signs of drop-out in the email data from the “Alcohol de Baas” intervention by Tactus. Our analyses indicate that the email texts contain information about drop-out, but as drop-out is a multidimensional construct, it remains a complex task to accurately predict who will drop out. Nevertheless, by taking this approach, we present insight into the possibilities of working with email data and present some preliminary findings (which stress the importance of a good working alliance between client and counselor, distinguish between formal and informal language, and highlight the importance of Tactus' internet forum)

The steady-state pharmacokinetics of efavirenz and nevirapine when used in combination in human immunodeficiency virus type 1-infected persons

The steady-state pharmacokinetics of efavirenz and nevirapine, when used in combination to treat human immunodeficiency virus type 1 (HIV-1)-infected subjects, were investigated. HIV-1-infected persons who had used efavirenz (600 mg once daily) for > or =2 weeks were eligible for study inclusion. The plasma pharmacokinetics of efavirenz were determined over 24 h. Subsequently, nevirapine (400 mg once daily) was added to the regimen. After 4 weeks, the pharmacokinetics of efavirenz and nevirapine were assessed over 24 h. The differences between the pharmacokinetic parameters of efavirenz with and without nevirapine were analyzed, and the pharmacokinetics of nevirapine were compared with those in historical control patients. The exposure to efavirenz when combined with nevirapine was significantly decreased by 22% (area under the plasma concentration vs. time curve), 36% (minimum plasma concentration), and 17% (maximum plasma concentration). Nevirapine pharmacokinetics appear to be unaffected by coadministration of efavirenz, compared with data from historical control patient

The cardiac sodium channel displays differential distribution in the conduction system and transmural heterogeneity in the murine ventricular myocardium

Cardiac sodium channels are responsible for conduction in the normal and diseased heart. We aimed to investigate regional and transmural distribution of sodium channel expression and function in the myocardium. Sodium channel Scn5a mRNA and Na(v)1.5 protein distribution was investigated in adult and embryonic mouse heart through immunohistochemistry and in situ hybridization. Functional sodium channel availability in subepicardial and subendocardial myocytes was assessed using patch-clamp technique. Adult and embryonic (ED14.5) mouse heart sections showed low expression of Na(v)1.5 in the HCN4-positive sinoatrial and atrioventricular nodes. In contrast, high expression levels of Na(v)1.5 were observed in the HCN4-positive and Cx43-negative AV or His bundle, bundle branches and Purkinje fibers. In both ventricles, a transmural gradient was observed, with a low Na(v)1.5 labeling intensity in the subepicardium as compared to the subendocardium. Similar Scn5a mRNA expression patterns were observed on in situ hybridization of embryonic and adult tissue. Maximal action potential upstroke velocity was significantly lower in subepicardial myocytes (mean +/- SEM 309 +/- 32 V/s; n = 14) compared to subendocardial myocytes (394 +/- 32 V/s; n = 11; P < 0.05), indicating decreased sodium channel availability in subepicardium compared to subendocardium. Scn5a and Na(v)1.5 show heterogeneous distribution patterns within the cardiac conduction system and across the ventricular wall. This differential distribution of the cardiac sodium channel may have profound consequences for conduction disease phenotypes and arrhythmogenesis in the setting of sodium channel diseas