Oxidation of the borohydride Ion at silver nanoparticles on a glassy carbon electrode (GCE) using pulsed potential techniques

Direct oxidation borohydride fuel cells are very attractive energy conversion devices. Silver has been reported as one of the few materials which can catalyze an 8-electron oxidation. Potential step amperometric pulse techniques to synthesize nanostructured silver material on flat glassy carbon electrodes is reported and significant differences with bulk silver deposit have been observed. The oxidation of borohydride ion on the silver particles occurs at -0.025 V vs. SCE and the potential decreases towards negative values at longer cycle times. The oxidation current also decreases with the number of cycles, suggesting that the silver active sites become partially blocked by oxidation products of borohydride. The electroactive area per unit electrode area of silver was relatively low for particles deposited using potential step amperometric techniques on glassy carbon (0.002 cm2 per cm-2) compared with the area found at a polycrystalline silver electrode (0.103 cm2 per cm-2

Spatial distributed modelling of erosion and sediment transport in mountain catchments in the Pyrenees: challenges for calibration and validation

28 p., 10 Figs., 5 Tabls.Publicado inicialmente por la Universidad de La Rioja (España) en: Cuadernos de Investigación Geográfica 39(2) (2013)[EN] Most erosion models applied at basin scale are based on spatially aggregated representation, for example, in a space subdivision of the surfaces to which behavior is assumed homogeneous (sub-basins, hydrological units, etc.). This approach leads to a desirable simplification of the calculations, but presents difficulties in addressing problems related to sediment transport and identification of sediment source areas, which should be treated by a continuous spatial representation. Spatially distributed models, however, allow a more accurate approach to this problem, at the cost of an increased computational complexity. The objective of this work is the calibration and validation of the model WATEM/SEDEM, an empirical-conceptual spatially distributed model, to predict erosion and sediment yield in two watersheds in the Central Spanish Pyrenees: i) the watershed of the Barasona Reservoir (1504 km2), which is drained by the Esera and Isabena Rivers, the model calibration and validation was based on the depositional history of the Barasona Reservoir and suspended sediment records over 3 years (May 2005–May 2008) at the outlet of the Isabena River; ii) the experimental Arnas catchment (2.84 km2), the model calibration was performed based on a dataset of soil redistribution rates derived from point 137Cs inventories, allowing capture differences per land use in the main model parameters. The validation process was carried with the registration of six years of suspended sediment at the outlet of the Arnas catchment. The calibration process for watershed of the Barasona Reservoir showed the problem you have when trying to calibrate the parameters of transport capacity with a single variable (the export of sediment to the basin outlet), making impossible to find a single set of parameters that optimize the error function, making it necessary to adopt a compromise solution. For the experimental Arnas catchment the model calibration processes using spatially distributed sediment yield derived from 137Cs inventories allowed calibrating the empirical parameters of transport capacity in a satisfactory way, finding a single combination of values that optimizes the error function. These results show that the calibration parameters of transport capacity are a fundamental aspect of the model WATEM/SEDEM and other similar models. To obtain a reliable estimate of the spatial distribution of erosion and sediment transport requires a calibration and validation by means of spatially distributed data of soil loss, which in turn allows a calibration of spatially distributed parameters concerning transport capacity.[ES] Una gran parte de los modelos de erosion aplicados a escala de cuenca se basan en una representacion espacialmente agregada, es decir en la subdivision del espacio en superficies a las que se supone un comportamiento homogeneo (subcuencas, unidades hidrologicas, etc.). Esta aproximacion conlleva una deseable simplificacion de los calculos, pero presenta dificultades para abordar problemas relacionados con el transporte de sedimentos y la identificacion de areas fuente de sedimento, que deben tratarse mediante una representacion espacial continua. Los modelos espacialmente distribuidos, en cambio, permiten una aproximacion mas precisa a este problema, a costa de una mayor complejidad de calculo. El objetivo de este trabajo es la calibracion y validacion del modelo WATEM/SEDEM, un modelo empirico-conceptual espacialmente distribuido, para predecir erosion y la produccion de sedimentos en dos cuencas del Pirineo aragones: i) la cuenca del embalse de Barasona (1504 km2), drenada por los rios Esera e Isabena, donde la base de datos para el proceso de calibracion fue el registro de 3 anos de sedimentos en suspension (mayo 2005-mayo 2008) a la salida de la subcuenca del Rio Isabena y para la validacion se utilizo el registro historico de sedimentacion del embalse de Barasona; y, ii) la cuenca experimental de Arnas (2.84 km2), donde se conto para la calibracion con datos espacialmente distribuidos de tasas de erosion y sedimentacion derivadas de inventarios de Cs137, mas el registro de seis anos de sedimento en suspension a la salida de la cuenca de Arnas para el proceso de validacion. El proceso de calibracion para el embalse de Barasona mostro el problema que se tiene al intentar calibrar los parametros de capacidad de transporte con una sola variable (la exportacion de sedimento a la salida de la cuenca), haciendo imposible encontrar un solo conjunto de parametros que optimicen la funcion de error y obligando a adoptar una solucion de compromiso. En la cuenca de Arnas el uso de datos espacialmente distribuidos de produccion de sedimentos derivados de inventarios de Cs137 permitio calibrar los parametros empiricos de capacidad de transporte de una forma satisfactoria, encontrando una sola combinacion de valores que optimiza la funcion de error. Con los resultados obtenidos se demuestra que la calibracion de los parametros de capacidad de transporte es un aspecto fundamental de WATEM/SEDEM y de otros modelos similares. Para obtener una estimacion fiable de la distribucion espacial de los procesos de erosion y transporte de sedimento se requiere de una calibracion y validacion con datos espacialmente distribuidos de perdida o ganancia de suelo que permita a su vez realizar una calibracion espacialmente distribuida de los parametros relativos a la capacidad de transporte.Este trabajo se ha llevado a cabo con el apoyo del proyecto INDICA (CGL2011- 27753-C02-01 y -02), financiado por el Ministerio de Economia y Competitividad, el proyecto ACQWA (FP7-ENV-2007-1-212250), financiado por la Comision Europea y un acuerdo entre el CSIC y el Ministerio de Medio Ambiente (RESEL). N. Lana-Renault ha disfrutado de un contrato de investigacion en el Programa Juan de la Cierva (Ministerio de Economia y Competitividad). En este articulo han participado numerosos colegas del Departamento de Procesos Geoambientales y Cambio Global del Instituto Pirenaico de Ecologia (IPE), asi como del Departamento de Suelo y Agua de la Est. Exp. Aula Dei (EEAD-CSIC).Peer reviewe

Effects of incidental physical activity on morphosyntactic processing in aging

Older adults have difficulties in sentence comprehension when working memory (WM) load increases (e.g., multiple embedded clauses). Structured physical activity has been related to improvements in cognition; however, incidental physical activity (PA, i.e., unstructured daily physical activities), particularly incidental vigorous activity has been poorly studied in relation to its effects on behavior. Furthermore, no positive effect on language has been reported in either form of physical activity. The aim of this study was to evaluate how two levels of PA (high or low) affect WM processing and how this, in turn, may affect morphosyntactic processing in older adults. Individuals with high PA (n = 18) had a higher WM load effect than those with low PA (n = 18), both behaviorally (greater differences between high and low WM loads in correct responses) and in terms of event-related potentials (only subjects with high PA showed LAN and P600b amplitude differences between high and low WM loads). These findings suggest that PA promotes cognitive strategies to face WM loads and morphosyntactic processing

A youth empowerment intervention to prevent childhood obesity: design and methods for a cluster randomized trial of the H2GO! program

BACKGROUND: Reducing sugar-sweetened beverage (SSB) consumption is a promising dietary target for childhood obesity prevention. This paper describes the design and methods of a cluster randomized trial of H2GO!, a youth empowerment intervention to prevent childhood obesity through reducing SSB consumption among a low-income, ethnically diverse sample of youth. METHODS: This cluster randomized controlled trial is an academic-community partnership with the Massachusetts Alliance of Boys and Girls Clubs (BGC). Ten BGC sites will be randomly assigned to the H2GO! intervention or a wait-list, usual care control. Eligible study participants will be N = 450 parent-child pairs (youth ages 9-12 years and their parents/caregivers) recruited from participating BGCs. The 6-week in-person H2GO! intervention consists of 12 group-based sessions delivered by BGC staff and youth-led activities. An innovative feature of the intervention is the development of youth-produced narratives as a strategy to facilitate youth empowerment and parental engagement. Child outcomes include measured body mass index z scores (zBMI), beverage intake, and youth empowerment. Parent outcomes include beverage intake and availability of SSBs at home. Outcomes will be measured at baseline and at 2, 6, and 12 months. With a 75% retention rate, the study is powered to detect a minimum group difference of 0.1 zBMI units over 12 months. DISCUSSION: Empowering youth may be a promising intervention approach to prevent childhood obesity through reducing SSB consumption. This intervention was designed to be delivered through BGCs and is hypothesized to be efficacious, relevant, and acceptable for the target population of low-income and ethnically diverse youth. TRIAL REGISTRATION: ClinicalTrials.gov NCT04265794 . Registered 11 February 2020

Atypical Lemierre’s syndrome caused by Prevotella oris

Lemierre’s syndrome is a rare form of severe sepsis secondary to oropharyngeal infection characterized by septic thrombophlebitis of the internal jugular vein with disseminated infections, with the lungs being the most frequent target. We report the case of a previously healthy 15-year-old admitted to the intensive care unit because of septic shock, brain and lung abscesses, and a positive blood culture for Prevotella oris with a clinical presentation compatible with the diagnosis of Lemierre’s syndrome. Conclusion: This is an atypical presentation of Lemierre’s syndrome because of the isolated microorganism

Temporal changes of NDVI for qualitative environmental assessment of mangroves: Shrimp farming impact on the health decline of the arid mangroves in the Gulf of California (1990-2010)

We assessed the temporal evolution of vegetation activity of mangroves in the Southeastern coastal of the Gulf of California (Mexico) through a multi-temporal analysis of Landsat TM images from 1990 to 2010 where time series of the Normalized Difference Vegetation Index (NDVI) were obtained. A multivariate regression analysis showed the presence of statistically significant negative trends of NDVI (low vegetation activity) in the coverage of mangrove forest, mangrove forest with pickleweed, and pickleweed; however, we did not found any meteorological variable (built time series of average minimum and maximum temperatures, and of accumulated rainfall) that controlled the observed trends. A pixel-by-pixel spatially distributed analysis of the temporal trends of NDVI, complemented by digitalization through photo interpretation of the shrimp farms present in the study area, showed a spatial relationship between the zones of greatest loss of vegetation activity (1990–2010) and the areas with greater proliferation of shrimp farms in the study area. Our study demonstrated the applicability of NDVI for the environmental assessment of mangroves. The relationship between changes in remote sensing indices and environmental variables allows for an efficient evaluation of the main environmental impacts, which can be used for coastal planning and management.The research was supported by the Mexican Secretary of Natural Resources and Environment (SEMARNAT-CONACYT; grant number SEMARNAT-2002-C01-0147). SM-B and RJM are students of Academic Program of Geoinformatics (UACJ).Peer Reviewe

Striatum-projecting prefrontal cortex neurons support working memory maintenance

Neurons in the medial prefrontal cortex (mPFC) are functionally linked to working memory (WM) but how distinct projection pathways contribute to WM remains unclear. Based on optical recordings, optogenetic perturbations, and pharmacological interventions in male mice, we report here that dorsomedial striatum (dmStr)-projecting mPFC neurons are essential for WM maintenance, but not encoding or retrieval, in a T-maze spatial memory task. Fiber photometry of GCaMP6m-labeled mPFC→dmStr neurons revealed strongest activity during the maintenance period, and optogenetic inhibition of these neurons impaired performance only when applied during this period. Conversely, enhancing mPFC→dmStr pathway activity—via pharmacological suppression of HCN1 or by optogenetic activation during the maintenance period—alleviated WM impairment induced by NMDA receptor blockade. Moreover, cellular-resolution miniscope imaging revealed that >50% of mPFC→dmStr neurons are active during WM maintenance and that this subpopulation is distinct from neurons active during encoding and retrieval. In all task periods, neuronal sequences were evident. Striatum-projecting mPFC neurons thus critically contribute to spatial WM maintenance