1,006 research outputs found

    Estimation of high return period flood quantiles using additional non-systematic information with upper bounded statistical models

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    This paper proposes the estimation of high return period quantiles using upper bounded distribution functions with Systematic and additional Non-Systematic information. The aim of the developed methodology is to reduce the estimation uncertainty of these quantiles, assuming the upper bound parameter of these distribution functions as a statistical estimator of the Probable Maximum Flood (PMF). Three upper bounded distribution functions, firstly used in Hydrology in the 90's (referred to in this work as TDF, LN4 and EV4), were applied at the Jucar River in Spain. Different methods to estimate the upper limit of these distribution functions have been merged with the Maximum Likelihood (ML) method. Results show that it is possible to obtain a statistical estimate of the PMF value and to establish its associated uncertainty. The behaviour for high return period quantiles is different for the three evaluated distributions and, for the case study, the EV4 gave better descriptive results. With enough information, the associated estimation uncertainty for very high return period quantiles is considered acceptable, even for the PMF estimate. From the robustness analysis, the EV4 distribution function appears to be more robust than the GEV and TCEV unbounded distribution functions in a typical Mediterranean river and Non-Systematic information availability scenario. In this scenario and if there is an upper limit, the GEV quantile estimates are clearly unacceptable

    Aplicación de la teoría de robots manipuladores a la biomecánica del brazo humano1

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    ResumenEste artículo presenta la aplicación de un conjunto de técnicas propias de la teoría de los robots manipuladores al estudio del movimiento del brazo humano. Para ello el brazo humano se modela como un robot manipulador redundante. En particular se aplica el concepto de índices de desempeño para predecir posturas óptimas del brazo durante la realización de tareas. En el estudio se incluyen tanto posiciones estáticas, como secuencias de posiciones para la formulación de trayectorias óptimas de movimiento

    Calcium silicate and calcium hydroxide materials for pulp capping: biointeractivity, porosity, solubility and bioactivity of current formulations

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    AIM: The chemical-physical properties of novel and long-standing calcium silicate cements versus conventional pulp capping calcium hydroxide biomaterials were compared. METHODS: Calcium hydroxide-based (Calxyl, Dycal, Life, Lime-Lite) and calcium silicate-based (ProRoot MTA, MTA Angelus, MTA Plus, Biodentine, Tech Biosealer capping, TheraCal) biomaterials were examined. Calcium and hydroxyl ion release, water sorption, interconnected open pores, apparent porosity, solubility and apatite-forming ability in simulated body fluid were evaluated. RESULTS: All calcium silicate materials released more calcium. Tech Biosealer capping, MTA Plus gel and Biodentine showed the highest values of calcium release, while Lime-Lite the lowest. All the materials showed alkalizing activity except for Life and Lime-Lite. Calcium silicate materials showed high porosity values: Tech Biosealer capping, MTA Plus gel and MTA Angelus showed the highest values of porosity, water sorption and solubility, while TheraCal the lowest. The solubility of water-containing materials was higher and correlated with the liquid-to-powder ratio. Calcium phosphate (CaP) deposits were noted on materials surfaces after short aging times. Scant deposits were detected on Lime-Lite. A CaP coating composed of spherulites was detected on all calcium silicate materials and Dycal after 28 days. The thickness, continuity and Ca/P ratio differed markedly among the materials. MTA Plus showed the thickest coating, ProRoot MTA showed large spherulitic deposits, while TheraCal presented very small dense spherulites. CONCLUSIONS: calcium silicate-based cements are biointeractive (ion-releasing) bioactive (apatite-forming) functional biomaterials. The high rate of calcium release and the fast formation of apatite may well explain the role of calcium silicate biomaterials as scaffold to induce new dentin bridge formation and clinical healing

    Assessment of and Response to Data Needs of Clinical and Translational Science Researchers and Beyond

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    Objective and Setting: As universities and libraries grapple with data management and “big data,” the need for data management solutions across disciplines is particularly relevant in clinical and translational science (CTS) research, which is designed to traverse disciplinary and institutional boundaries. At the University of Florida Health Science Center Library, a team of librarians undertook an assessment of the research data management needs of CTS researchers, including an online assessment and follow-up one-on-one interviews. Design and Methods: The 20-question online assessment was distributed to all investigators affiliated with UF’s Clinical and Translational Science Institute (CTSI) and 59 investigators responded. Follow-up in-depth interviews were conducted with nine faculty and staff members. Results: Results indicate that UF’s CTS researchers have diverse data management needs that are often specific to their discipline or current research project and span the data lifecycle. A common theme in responses was the need for consistent data management training, particularly for graduate students; this led to localized training within the Health Science Center and CTSI, as well as campus-wide training. Another campus-wide outcome was the creation of an action-oriented Data Management/Curation Task Force, led by the libraries and with participation from Research Computing and the Office of Research. Conclusions: Initiating conversations with affected stakeholders and campus leadership about best practices in data management and implications for institutional policy shows the library’s proactive leadership and furthers our goal to provide concrete guidance to our users in this area

    Coal-CO2 Slurry Feed for Pressurized Gasifiers: Slurry Preparation System Characterization and Economics

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    AbstractGasification-based plants with coal-CO2 slurry feed are predicted to be more efficient than those with coal-water slurry feed. This is particularly true for high moisture, low rank coal such as lignite. Nevertheless, preparation of the CO2 slurry is challenging and the losses associated with this process have not been accounted for in previous analyses. This work introduces the Phase Inversion-based Coal-CO2 Slurry (PHICCOS) feeding system, in which coal-CO2 slurry is prepared at ambient temperature via coal-water slurry. Steady-state process simulation is used to estimate the performance of the proposed slurry preparation and feeding system for bituminous coal and lignite. An Integrated Gasification Combined Cycle (IGCC) power plant with carbon capture is used here as a potential application, but this concept is applicable to any high-pressure coal feeding process. The economic attractiveness of the PHICCOS feeding system is assessed through calculation of its capital costs and resulting levelized cost of electricity, relative to competing commercial technologies. The findings of this work show that the PHICCOS feeding system offers a good tradeoff between overall process performance and costs. It is the most cost-effective method for feeding lignite and the second most attractive for bituminous coal, for which the competing technology is marginally cheaper. The PHICCOS feeding system is hence the only feeding system which is consistently cost-effective across the entire coal rank spectrum and is increasingly so for high-moisture and high-ash coal

    Regulating human interventions in Colombian coastal areas: Implications for the environmental licensing procedure in middle-income countries

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    Although anthropogenic impacts could be assessed in any environment, coastal areas pose a particular challenge because of their special nature as the interface between land and sea. Therefore, this study evaluates the environmental regulatory framework for coastal interventions in Colombia, as an archetype of medium income countries (MICs), to derive implications for the environmental licensing procedure (ELP). The methods comprised two simultaneous pathways: a. An inventory of human interventions at the large scale area of the Colombian Caribbean Coast, with an estimation of the overall environmental impact; b. An analysis of the ELP in Colombia during the last 25 years. The study evidences several weaknesses, such as a consistent reduction in the number of works and activities covered in each new legislative. Moreover, the Colombian ELP currently regulates only four of the ten types of interventions with greater effect in its coastal zones. The discussions highlight some policy implications for the ELP in MICs, mainly based on how the impact of a type of intervention can be magnified in proportion to its frequency of occurrence, and the need to articulate instruments of environmental management and territorial planning. At last, the need to evolve the impact assessment of human interventions from environmental factors toward socio-natural processes is evidenced and further addressed, by the introduction of a susceptibility approach inspired on geomorphological processes. Overall, this study highlights important gaps of the Colombian ELP for coastal environments, which entails valuable lessons for MICs

    Flood frequency analysis of historical flood data under stationary and non-stationary modelling

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    Historical records are an important source of information on extreme and rare floods and fundamental to establish a reliable flood return frequency. The use of long historical records for flood frequency analysis brings in the question of flood stationarity, since climatic and land-use conditions can affect the relevance of past flooding as a predictor of future flooding. In this paper, a detailed 400 yr flood record from the Tagus River in Aranjuez (central Spain) was analysed under stationary and non-stationary flood frequency approaches, to assess their contribution within hazard studies. Historical flood records in Aranjuez were obtained from documents (Proceedings of the City Council, diaries, chronicles, memoirs, etc.), epigraphic marks, and indirect historical sources and reports. The water levels associated with different floods (derived from descriptions or epigraphic marks) were computed into discharge values using a one-dimensional hydraulic model. Secular variations in flood magnitude and frequency, found to respond to climate and environmental drivers, showed a good correlation between high values of historical flood discharges and a negative mode of the North Atlantic Oscillation (NAO) index. Over the systematic gauge record (1913–2008), an abrupt change on flood magnitude was produced in 1957 due to constructions of three major reservoirs in the Tagus headwaters (Bolarque, Entrepeñas and Buendia) controlling 80% of the watershed surface draining to Aranjuez. Two different models were used for the flood frequency analysis: (a) a stationary model estimating statistical distributions incorporating imprecise and categorical data based on maximum likelihood estimators, and (b) a time-varying model based on "generalized additive models for location, scale and shape" (GAMLSS) modelling, which incorporates external covariates related to climate variability (NAO index) and catchment hydrology factors (in this paper a reservoir index; RI). Flood frequency analysis using documentary data (plus gauged records) improved the estimates of the probabilities of rare floods (return intervals of 100 yr and higher). Under non-stationary modelling flood occurrence associated with an exceedance probability of 0.01 (i.e. return period of 100 yr) has changed over the last 500 yr due to decadal and multi-decadal variability of the NAO. Yet, frequency analysis under stationary models was successful in providing an average discharge around which value flood quantiles estimated by non-stationary models fluctuate through time

    Formalising new arrival enterprises: challenges of new ethnic entrepreneurship for business support policy.

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    There has been little research carried out on ethnic entrepreneurship and the informal economy, especially among new and emerging ethnic minority business communities in the UK. Informality is however estimated not only to be an important phenomenon among these groups but seems also to underlie the existing gap between entrepreneurs and business support policies. This project identifies, localises, and characterises the new and emerging ethnic minority business communities in London. It then critically examines the nature of informality among these groups and the challenges that this poses to enterprise policy. The research methodology comprised a review of existing literature and case studies of new immigrant entrepreneurs (50 in total) and community-based organisations and business advisors (15 in total). Primary data was collected using semi structured interviews, field observations, and casual encounters with entrepreneurs and key informants
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