242 research outputs found

    Surrogate-based optimization of tidal turbine arrays: a case study for the Faro-Olhão inlet

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    This paper presents a study for estimating the size of a tidal turbine array for the Faro-Olhão Inlet (Potugal) using a surrogate optimization approach. The method compromises problem formulation, hydro-morphodynamic modelling, surrogate construction and validation, and constraint optimization. A total of 26 surrogates were built using linear RBFs as a function of two design variables: number of rows in the array and Tidal Energy Converters (TECs) per row. Surrogates describe array performance and environmental effects associated with hydrodynamic and morphological aspects of the multi inlet lagoon. After validation, surrogate models were used to formulate a constraint optimization model. Results evidence that the largest array size that satisfies performance and environmental constraints is made of 3 rows and 10 TECs per row.Eduardo González-Gorbeña has received funding for the OpTiCA project (http://msca-optica.eu/) from the Marie Skłodowska-Curie Actions of the European Union's H2020-MSCA-IF-EF-RI-2016 / GA#: 748747. The paper is a contribution to the SCORE pro-ject, funded by the Portuguese Foundation for Science and Technology (FCT–PTDC/AAG-TEC/1710/2014). André Pacheco was supported by the Portuguese Foun-dation for Science and Technology under the Portuguese Researchers’ Programme 2014 entitled “Exploring new concepts for extracting energy from tides” (IF/00286/2014/CP1234).info:eu-repo/semantics/publishedVersio

    EFECTO IN VITRO DEL EXTRACTO ETANÓLICO DE CAULERPA FILIFORMIS EN PARÁMETROS SEMINALES HUMANOS

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    El objetivo de este estudio fue determinar el efecto in vitro del extracto etanólico de Caulerpa filiformis en parámetros seminales  humanos. Se realizaron las siguientes pruebas: vitalidad, motilidad y dispersión de cromatina espermática; tomándose en cuenta las  variables tiempo (5’, 15’, 35’ y 60’) y concentración (0.04mg/ml, 0.4mg/ml y 4 mg/ml) para cada prueba. La muestra fue diluida hasta una concentración de 10 x 106 de espermatozoides/ml con suero fisiológico al 0.9%, luego incubada 1:1 (v/v) con el extracto. Con respecto a la vitalidad, a partir de los 15 minutos el extracto produjo mortalidad espermática. La DL50 fue de 17.35 mg/ml (11.08-57.17 mg/ml), 8.75 mg/ml (7.15-12.00 mg/ml) y 6.43 mg/ml (5.53-8.02 mg/ml) para los 15’, 35’ y 60’, respectivamente. En cuanto a la motilidad espermática se observó una disminución significativa con respecto al control en la concentración de 4mg/ml en los 15’ y 35’. A los 60’ en dicha concentración, todas las repeticiones alcanzaron una inmovilización espermática total. La CE50 a los 60’ fue de 0.49 mg/ml (-1.25-1.16 mg/ml). La prueba de ANOVA de 2 vías mostróque tanto el porcentaje de mortalidad como de espermatozoides inmovilizados se vio afectado por las variables tiempo y concentración, mientras que la interacción de éstas solo afectó la motilidad. El parámetro motilidad solo muestra un efecto dosis dependiente en la concentración de 4 mg/ml. La fragmentación de ADN no se vio afectada por ninguna de las variables ya mencionadas ni por la interacción de estas. Los resultados obtenidos con el extracto etanólico de Caulerpa filiformis podrían tener una naturaleza contraceptiva promisoria, y tal vez ser tomada en cuenta como una alternativa a los espermicidas comerciales, para ello se necesitará futuros estudios que develen la composición química de esta especie

    Evidence for three genetic loci involved in both anorexia nervosa risk and variation of body mass index

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    The maintenance of normal body weight is disrupted in patients with anorexia nervosa (AN) for prolonged periods of time. Prior to the onset of AN, premorbid body mass index (BMI) spans the entire range from underweight to obese. After recovery, patients have reduced rates of overweight and obesity. As such, loci involved in body weight regulation may also be relevant for AN and vice versa. Our primary analysis comprised a cross-trait analysis of the 1000 single nucleotide polymorphisms (SNPs) with the lowest p-values in a genome-wide association meta-analysis (GWAMA) of AN (GCAN) for evidence of association in the largest published GWAMA for BMI (GIANT). Subsequently we performed sex-stratified analyses for these 1000 SNPs. Functional ex vivo studies on four genes ensued. Lastly, a look-up of GWAMA-derived BMI related loci was performed in the AN GWAMA. We detected significant associations (p-values < 5×10−5, Bonferroni corrected p < 0.05) for 9 SNP alleles at 3 independent loci. Interestingly, all AN susceptibility alleles were consistently associated with increased BMI. None of the genes (chr. 10: CTBP2, chr. 19: CCNE1, chr. 2: CARF and NBEAL1; the latter is a region with high linkage disequilibrium) nearest to these SNPs has previously been associated with AN or obesity. Sex-stratified analyses revealed that the strongest BMI signal originated predominantly from females (chr. 10 rs1561589; poverall: 2.47 × 10−06/pfemales: 3.45 × 10−07/pmales: 0.043). Functional ex vivo studies in mice revealed reduced hypothalamic expression of Ctbp2 and Nbeal1 after fasting. Hypothalamic expression of Ctbp2 was increased in diet induced obese (DIO) mice as compared to age-matched lean controls. We observed no evidence for associations for the look-up of BMI related loci in the AN GWAMA. A cross-trait analysis of AN and BMI loci revealed variants at three chromosomal loci with potential joint impact. The chromosome 10 locus is particularly promising given that the association with obesity was primarily driven by females. In addition, the detected altered hypothalamic expression patterns of Ctbp2 and Nbeal1 as a result of fasting and DIO implicate these genes in weight regulation

    The Swiss Vocational Education and Training System: What Can Spain Learn from Switzerland?

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    Switzerland is famous for its vocational education and training (VET) system. This article describes Switzerland's success in integrating adolescents into the labour market, with emphasis on two aspects. First, dual-track VET, which combines learning at school and in host companies, is an attractive choice for adolescents. It prepares them for the labour market and for progression routes to higher education. Second, the firm's decision to train could be an example of the prisoner's dilemma, but Switzerland has managed to sidestep that issue and minimize concerns about poaching. Finally, we discuss what Spain could learn from the Swiss VET system

    New therapeutic targets for osteoarthritis pain

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    Osteoarthritis (OA), the most common form of arthritis, causes pain and disability, as well as emotional distress. While total joint replacement is one of the most effective treatments available for improving the quality of life in people with severe OA, it is not suitable for all patients and all joints. Current pharmacological analgesics have limited efficacy, and their use is often restricted by adverse events. Medications that might reduce pain by slowing or preventing structural disease remain elusive. Our increasing understanding of the complex mechanisms that underlie OA pain offers a wide range of potential new treatment targets. New drugs for OA pain might come from repurposing those developed for other conditions, as well as novel compounds targeting pain mechanisms specific to the joint. Here we discuss the mechanisms of OA pain and its therapeutic implications. We explore evolving treatment modalities, including combination treatment. We review recent research and patents pointing to future OA therapies. We discuss the potential for biomarkers to facilitate drug development and targeting

    Norms, Networks, Power, and Control: Understanding Informal Payments and Brokerage in Cross-Border Trade in Sierra Leone

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    Recent research has cast light on the variety of informal payments and practices that govern the day-to-day interactions between traders and customs agents at border posts in low-income countries. Building on this literature, this paper draws on survey and qualitative evidence in an effort to explore which groups are most advantaged and disadvantaged by the largely informal processes and norms governing cross-border trade. We find that understanding variation in strategies and outcomes across traders can only be effectively understood with reference to the importance of norms, networks, power, and the logic of control.Department for International DevelopmentBill and Melinda Gates Foundatio

    EVA: Laparoscopic instrument tracking based on endoscopic video analysis for psychomotor skills assessment

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    INTRODUCTION: The EVA (Endoscopic Video Analysis) tracking system a new tracking system for extracting motions of laparoscopic instruments based on non-obtrusive video tracking was developed. The feasibility of using EVA in laparoscopic settings has been tested in a box trainer setup. METHODS: EVA makes use of an algorithm that employs information of the laparoscopic instrument's shaft edges in the image, the instrument's insertion point, and the camera's optical centre to track the 3D position of the instrument tip. A validation study of EVA comprised a comparison of the measurements achieved with EVA and the TrEndo tracking system. To this end, 42 participants (16 novices, 22 residents, and 4 experts) were asked to perform a peg transfer task in a box trainer. Ten motion-based metrics were used to assess their performance. RESULTS: Construct validation of the EVA has been obtained for seven motion-based metrics. Concurrent validation revealed that there is a strong correlation between the results obtained by EVA and the TrEndo for metrics such as path length (p=0,97), average speed (p=0,94) or economy of volume (p=0,85), proving the viability of EVA. CONCLUSIONS: EVA has been successfully used in the training setup showing potential of endoscopic video analysis to assess laparoscopic psychomotor skills. The results encourage further implementation of video tracking in training setups and in image guided surgery

    Learning curves of basic laparoscopic psychomotor skills in SINERGIA VR simulator

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    Purpose: Surgical simulators are currently essential within any laparoscopic training program because they provide a low-stakes, reproducible and reliable environment to acquire basic skills. The purpose of this study is to determine the training learning curve based on different metrics corresponding to five tasks included in SINERGIA laparoscopic virtual reality simulator. Methods: Thirty medical students without surgical experience participated in the study. Five tasks of SINERGIA were included: Coordination, Navigation, Navigation and touch, Accurate grasping and Coordinated pulling. Each participant was trained in SINERGIA. This training consisted of eight sessions (R1–R8) of the five mentioned tasks and was carried out in two consecutive days with four sessions per day. A statistical analysis was made, and the results of R1, R4 and R8 were pair-wise compared with Wilcoxon signed-rank test. Significance is considered at P value <0.005. Results: In total, 84.38% of the metrics provided by SINERGIA and included in this study show significant differences when comparing R1 and R8. Metrics are mostly improved in the first session of training (75.00% when R1 and R4 are compared vs. 37.50% when R4 and R8 are compared). In tasks Coordination and Navigation and touch, all metrics are improved. On the other hand, Navigation just improves 60% of the analyzed metrics. Most learning curves show an improvement with better results in the fulfillment of the different tasks. Conclusions: Learning curves of metrics that assess the basic psychomotor laparoscopic skills acquired in SINERGIA virtual reality simulator show a faster learning rate during the first part of the training. Nevertheless, eight repetitions of the tasks are not enough to acquire all psychomotor skills that can be trained in SINERGIA. Therefore, and based on these results together with previous works, SINERGIA could be used as training tool with a properly designed training program
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