207 research outputs found

    Gravity Currents in Aquatic Canopies

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    A lock exchange experiment is used to investigate the propagation of gravity currents through a random array of rigid, emergent cylinders which represents a canopy of aquatic plants. As canopy drag increases, the propagating front varies from the classic profile of an unobstructed gravity current to a triangular profile. Unlike the unobstructed lock exchange, the gravity current in the canopy decelerates with time as the front lengthens. Two drag-dominated regimes associated with linear and nonlinear drag laws are identified. The theoretical expression for toe velocity is supported by observed values. Empirical criteria are developed to predict the current regime from the cylinder Reynolds number and the array density.National Science Foundation (U.S.) (grant EAR0309188)National Science Foundation (U.S.) (grant EAR0509658)Massachusetts Institute of Technology (Presidential Graduate Fellowship

    Closing the sea surface mixed layer temperature budget from in situ observations alone: Operation Advection during BoBBLE

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    Sea surface temperature (SST) is a fundamental driver of tropical weather systems such as monsoon rainfall and tropical cyclones. However, understanding of the factors that control SST variability is lacking, especially during the monsoons when in situ observations are sparse. Here we use a ground-breaking observational approach to determine the controls on the SST variability in the southern Bay of Bengal. We achieve this through the first full closure of the ocean mixed layer energy budget derived entirely from in situ observations during the Bay of Bengal Boundary Layer Experiment (BoBBLE). Locally measured horizontal advection and entrainment contribute more significantly than expected to SST evolution and thus oceanic variability during the observation period. These processes are poorly resolved by state-of-the-art climate models, which may contribute to poor representation of monsoon rainfall variability. The novel techniques presented here provide a blueprint for future observational experiments to quantify the mixed layer heat budget on longer time scales and to evaluate these processes in models

    A Survey of Volunteered Open Geo-Knowledge Bases in the Semantic Web

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    Over the past decade, rapid advances in web technologies, coupled with innovative models of spatial data collection and consumption, have generated a robust growth in geo-referenced information, resulting in spatial information overload. Increasing 'geographic intelligence' in traditional text-based information retrieval has become a prominent approach to respond to this issue and to fulfill users' spatial information needs. Numerous efforts in the Semantic Geospatial Web, Volunteered Geographic Information (VGI), and the Linking Open Data initiative have converged in a constellation of open knowledge bases, freely available online. In this article, we survey these open knowledge bases, focusing on their geospatial dimension. Particular attention is devoted to the crucial issue of the quality of geo-knowledge bases, as well as of crowdsourced data. A new knowledge base, the OpenStreetMap Semantic Network, is outlined as our contribution to this area. Research directions in information integration and Geographic Information Retrieval (GIR) are then reviewed, with a critical discussion of their current limitations and future prospects

    The Impact of Acceptance and Commitment Training and Multicultural Training on the stigmatizing attitudes and professional burnout of substance abuse counselors

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    Empirically validated methods for reducing stigma and prejudice toward recipients of behavioral healthcare services are badly needed. In the present study, two packages presented in one day workshops were compared to a biologically oriented Educational Control condition in the alleviation of stigmatizing attitudes in drug abuse counselors. One, Acceptance and Commitment Training (ACT), utilized acceptance, defusion, mindfulness, and values methods. The other, Multicultural Training, sensitized participants to group prejudices and biases. Measures of stigma and burnout were taken pre-training, post-training, and after a three month follow-up. Results showed that Multicultural Training had an impact on stigmatizing attitudes and burnout post-intervention but not at follow-up, but showed better gains in a sense of personal accomplishment as compared to the Educational Control at follow-up. ACT had a positive impact on stigma at follow-up and on burnout at post-treatment and follow-up and follow-up gains in burnout exceeded those of Multicultural Training. ACT also significantly changed the believability of stigmatizing attitudes. This process mediated the impact of ACT but not Multicultural Training on follow-up stigma and burnout. This preliminary study opens new avenues for reducing stigma and burnout in behavioral health counselors

    The Implementation of Brazil Sustainable Urban Mobility Policy

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    Institute of Transport and Logistics Studies. Faculty of Economics and Business. The University of Sydne

    El trabajo de fin de grado: resultados desde una perspectiva de pares estudiantes/tutores

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    The research on Undergraduate Dissertation (UD) has been incorporating aspects of the tutor/ student interaction that have been shown to be crucial in explaining the student’s results. The tutorial support received during the realization of the UD - in nature and intensity - and its relationship with the final results deserves particular attention. The study of this relationship isthe objective of this paper that, through the analysis of the information provided by 178 students / supervisors pairs, investigates the relationships between the tutorial support (declared by the teaching staff) and the competences reached by the students (perceived by the students them -selves), and between these and the real grade reached in the UD. The results indicate that the tutorial support in each one of the phases of the work is significantly related to several competences that the students perceive to have reached. Specifically, the critical capacity is improved withthe intensity of the tutorial support in various phases of the work. The organization of time is perceived to be increased with the support in the first phases -design of research and objectives design- while the use of prior knowledge and oral and written communication skills are competenciesthat improve with the intensity of support in their final phases -elaboration of conclusions and drafting. All abilities determine the grade reached by students in the UD.La investigación sobre el Trabajo de Fin de Grado (TFG) ha ido incorporando aspectos de la interacción tutor-a/alumno-a que se han demostrado cruciales en la explicación de los resultados de estos últimos. Merece particular atención el apoyo tutorial recibido durante la realización del trabajo -en naturaleza e intensidad- y su relación con los resultados obtenidos. El estudio de esta relación es el objetivo de este artículo que, a través del análisis de la información aportada por 178 pares alumno-a/tutor-a, indaga en las relaciones entre el apoyo tutorial (declarado por el profesorado) y las competencias alcanzadas por el alumnado (percibidas por el propio estudiantado), y entre éstas y la nota real alcanzada en la materia. Los resultados indican que el apoyo tutorial en cada una de las fases del trabajo se relaciona significativamente con varias competencias que el alumnado percibe haber alcanzado. Concretamente, la capacidad crítica se ve mejorada con la intensidad del apoyo tutorial en varias fases del trabajo. La organización del tiempo y la identificación de limitaciones se perciben incrementadas con el apoyo en las primeras fases -diseño de la investigación y definición de objetivos- mientras que el uso de conocimientos previos y la capacidad de comunicación oral y escrita son competencias que mejoran con la intensidad del apoyo en sus fases finales -elaboración de conclusiones y redacción-. Todas las capacidades determinan la calificación alcanzada por los estudiantes. 

    Long-term cropping system studies support intensive and responsive cropping systems in the low-rainfall Australian Mallee

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    Continuous-cropping systems based on no-till and crop residue retention have been widely adopted across the low-rainfall cereal belt in southern Australia in the last decade to manage climate risk and wind erosion. This paper reports on two long-term field experiments that were established in the late 1990s on texturally different soil types at a time of uncertainty about the profitability of continuous-cropping rotations in low-rainfall environments. Continuous-cereal systems significantly outyielded the traditional pasture–wheat systems in five of the 11 seasons at Waikerie (light-textured soil), resulting in a cumulative gross margin of AU$1600 ha–1 after the initial eight seasons, almost double that of the other treatments. All rotation systems at Kerribee (loam-textured soil) performed poorly, with only the 2003 season producing yields close to 3 t ha–1 and no profit achieved in the years 2004–08. For low-rainfall environments, the success of a higher input cropping system largely depends on the ability to offset the losses in poor seasons by capturing greater benefits from good seasons; therefore, strategies to manage climatic risk are paramount. Fallow efficiency, or the efficiency with which rainfall was stored during the period between crops, averaged 17% at Kerribee and 30% at Waikerie, also indicating that soil texture strongly influences soil evaporation. A ‘responsive’ strategy of continuous cereal with the occasional, high-value ‘break crop’ when seasonal conditions are optimal is considered superior to fixed or pasture–fallow rotations for controlling grass, disease or nutritional issues

    Dog Burials Associated with Human Burials in the West Indies during the Early Pre-Columbian Ceramic Age (500 BC-600 AD)

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    Across the Caribbean, the widespread presence of canine remains at archaeological sites from the Saladoid period raises questions about the role of “man’s best friend.” Dog (Canis familiaris) remains have been found located in both refuse middens and burials adjacent to human graves in a number of sites in the French Antilles and Barbuda, West Indies. This paper will critically examine dog remains and discuss the varied duality of the dog’s role in the Saladoid world: from food source to lifelong companion. The importance of dogs within Amerindian sites from Saint Martin, the Guadeloupe archipelago, Martinique and Barbuda will be explored from a zooarchaeological perspective, concluding with a critical discussion of changes in cultural patterns, as seen through the decline in dog remains during the Troumassoid and Suazoid period at the sites in the French Antilles. Résumé Sépultures de chiens associées à des sépultures humaines dans les Petites Antilles à l’Âge du Néoindien ancien (500 av. – 600 ap. J.-C.). Dans les Antilles, la présence généralisée de restes de chiens sur les sites de la période céramique ancienne Saladoïde soulève des questions sur le rôle de ce « meilleur ami de l’homme ». En effet, des chiens (Canis familiaris) ont été trouvés aussi bien dans des zones de rejets, qu’enterrés aux côtés de sépultures humaines dans un certain nombre de sites des Petites Antilles. Ce document examinera ces restes de chiens de façon critique et décrira les morphologies particulières des chiens des sites amérindiens de l’île de Saint-Martin, l\u27archipel de la Guadeloupe, la Martinique et de l’île de Barbuda, dans une perspective archéozoologique. Une discussion critique portera sur l\u27évolution des changements des modèles culturels, comme celui de la chute drastique des chiens enterrés pendant les périodes archéologiques plus tardives, Troumassoïde et Suazoïde, des sites des Antilles françaises. Enfin, la discussion portera sur la dualité du rôle du chien dans le monde Saladoïde, à la fois source de nourriture et compagnon de vie
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