790 research outputs found
Cubipod® Armor Design in Depth-Limited Regular Wave-Breaking Conditions
[EN] Armor stability formulas for mound breakwaters are commonly based on 2D small-scale physical tests conducted in non-overtopping and non-breaking conditions. However, most of the breakwaters built around the world are located in breaking or partially-breaking wave conditions, where they must withstand design storms having some percentage of large waves breaking before they reach the structure. In these cases, the design formulas for non-breaking wave conditions are not fully valid. This paper describes the specific 2D physical model tests carried out to analyze the trunk hydraulic stability of single- and double-layer Cubipod (R) armors in depth-limited regular wave breaking and non-overtopping conditions with horizontal foreshore (m = 0) and armor slope (alpha) with cot alpha = 1.5. An experimental methodology was established to ensure that 100 waves attacked the armor layer with the most damaging combination of wave height (H) and wave period (T) for the given water depth (h(s)). Finally, for a given water depth, empirical formulas were obtained to estimate the Cubipod (R) size which made the armor stable regardless of the deep-water wave storm.This research was funded by Conselleria d'Educacio, Investigacio, Cultura i Esport (Generalitat Valenciana) under grant GV/2017/031.Gómez-Martín, ME.; Herrera, MP.; Gonzalez-Escriva, J.; Medina, JR. (2018). Cubipod® Armor Design in Depth-Limited Regular Wave-Breaking Conditions. Journal of Marine Science and Engineering. 6(4):150-161. https://doi.org/10.3390/jmse6040150S15016164Herrera, M. P., Gómez-Martín, M. E., & Medina, J. R. (2017). Hydraulic stability of rock armors in breaking wave conditions. Coastal Engineering, 127, 55-67. doi:10.1016/j.coastaleng.2017.06.010Battjes, J. A., & Groenendijk, H. W. (2000). Wave height distributions on shallow foreshores. Coastal Engineering, 40(3), 161-182. doi:10.1016/s0378-3839(00)00007-7Medina, J. R., & Gómez-Martín, M. E. (2012). KD AND SAFETY FACTORS OF CONCRETE ARMOR UNITS. Coastal Engineering Proceedings, 1(33), 29. doi:10.9753/icce.v33.structures.29Melby, J. A., & Kobayashi, N. (1998). Progression and Variability of Damage on Rubble Mound Breakwaters. Journal of Waterway, Port, Coastal, and Ocean Engineering, 124(6), 286-294. doi:10.1061/(asce)0733-950x(1998)124:6(286)Van Gent, M. R. A. (2013). Rock stability of rubble mound breakwaters with a berm. Coastal Engineering, 78, 35-45. doi:10.1016/j.coastaleng.2013.03.003Celli, D., Pasquali, D., De Girolamo, P., & Di Risio, M. (2018). Effects of submerged berms on the stability of conventional rubble mound breakwaters. Coastal Engineering, 136, 16-25. doi:10.1016/j.coastaleng.2018.01.011Concrete Layer Innovation (CLI) http://www.concretelayer.com/documentationGuidelines for Xbloc Concept Designs https://www.xbloc.com/sites/default/files/domain-671/documents/xbloc-design-guidelines-2014-671-15039173271578936988.pdfGómez-Martín, M. E., & Medina, J. R. (2014). Heterogeneous Packing and Hydraulic Stability of Cube and Cubipod Armor Units. Journal of Waterway, Port, Coastal, and Ocean Engineering, 140(1), 100-108. doi:10.1061/(asce)ww.1943-5460.0000223Medina, J. R., Hudspeth, R. T., & Fassardi, C. (1994). Breakwater Armor Damage due to Wave Groups. Journal of Waterway, Port, Coastal, and Ocean Engineering, 120(2), 179-198. doi:10.1061/(asce)0733-950x(1994)120:2(179)Herrera, M. P., & Medina, J. R. (2015). Toe berm design for very shallow waters on steep sea bottoms. Coastal Engineering, 103, 67-77. doi:10.1016/j.coastaleng.2015.06.005Herrera, M. P., Molines, J., & Medina, J. R. (2016). Hydraulic stability of nominal and sacrificial toe berms for mound breakwaters on steep sea bottoms. Coastal Engineering, 114, 361-368. doi:10.1016/j.coastaleng.2016.05.00
Fatty Acid Methyl Esters as Biosolvents of Epoxy Resins: A Physicochemical Study
The C8 to C18 fatty acid methyl esters (FAME) have been compared as solvents for two epoxy resin pre-polymers, bisphenol A diglycidyl ether (DGEBA) and triglycidyl paminophenol ether (TGPA). It was found that the solubilization limits vary according to the ester and that methyl caprylate is the best solvent of both resins. To explain these solubility performances, physical and chemical properties of FAME were studied, such as the Hansen parameters, viscosity, binary diffusion coefficient and vaporization enthalpy. Determination of the physicochemical parameters of FAME was carried out by laboratory experimentations and by calculation from bibliographic data. The Hansen parameters of FAME and epoxy resins pre-polymers were theoretically and experimentally determined. The FAME chain length showed a long dependence on the binary diffusion parameters and kinematic viscosity, which are mass and momentum transport properties. Moreover, the vaporization enthalpy of these compounds was directly correlated with the solubilization limits
Metal-insulator transition in one-dimensional lattices with chaotic energy sequences
We study electronic transport through a one-dimensional array of sites by
using a tight binding Hamiltonian, whose site-energies are drawn from a chaotic
sequence. The correlation degree between these energies is controlled by a
parameter regulating the dynamic Lyapunov exponent measuring the degree of
chaos. We observe the effect of chaotic sequences on the localization length,
conductance, conductance distribution and wave function, finding evidence of a
Metal-Insulator Transition (MIT) at a critical degree of chaos. The
one-dimensional metallic phase is characterized by a Gaussian conductance
distribution and exhibits a peculiar non-selfaveraging.Comment: 5 pages, 5 figures (one figure replaced). Includes new results and a
few additional references. Improved style for publication. Accepted in
Physics Letters
NP7 protects from cell death induced by oxidative stress in neuronal and glial midbrain cultures from parkin null mice
AbstractParkin mutations produce Parkinson’s disease (PD) in humans and nigrostriatal dopamine lesions related to increased free radicals in mice. We examined the effects of NP7, a synthetic, marine derived, free radical scavenger which enters the brain, on H2O2 toxicity in cultured neurons and glia from wild-type (WT) and parkin null mice (PK-KO).NP7, 5–10μM, prevented the H2O2 induced apoptosis and necrosis of midbrain neuronal and glial cultures from WT and PK-KO mice. NP7 suppressed microglial activation and the H2O2 induced drop-out of dopamine neurons. Furthermore, NP7 prevented the increased phosphorylation of ERK and AKT induced by H2O2. NP7 may be a promising neuroprotector against oxidative stress in PD
Effects of the whole seed and a protein isolate of faba bean (Vicia faba) on the cholesterol metabolism of hypercholesterolaemic rats
The aim of the present work was to analyse the hypocholesterolaemic efficiency of a Vicia fabaprotein
isolate in relation to the intact legume. In addition, the mechanisms underlying the
effects of this isolate were investigated. Hypercholesterolaemic rats were divided into three
groups n10 3 and fed high-fat diets rich in cholesterol-containing casein, whole seeds of
Vicia faba or the protein isolate of faba beans as protein source, for 2 weeks ad libitum. The
protein isolate was prepared by isoelectric precipitation and spray dried. Analyses of serum,
liver and faeces, as well as of the activity of hepatic 3-hydroxy-3-methylglutaryl (HMG)-CoA
reductase, were assessed by enzymatic methods. The rats fed on Vicia faba diets showed
significantly lower body weights and energy intakes than rats fed on casein diets. The wholeseed
diet induced a significant reduction in plasma triacylglycerol. Feeding rats on diets
containing faba bean seeds, or the protein isolate, induced a significant decrease in plasma
(LDL+VLDL)-cholesterol but not in HDL-cholesterol. Hepatic cholesterol and triacylglycerol
were also reduced. The hypocholesterolaemic effects of Vicia faba were not the result of a
reduction in cholesterol synthesis as assessed from HMG-CoA reductase activity, but the result
of an increase in steroid faecal excretion. The faba bean-protein isolate obtained under our
experimental conditions was useful in improving the metabolic alterations induced by feeding
with a hypercholesterolaemic diet compared with casein. The effectiveness of the whole seeds
was higher than that of the protein isolate
Does evidence support the high expectations placed in precision medicine? A bibliographic review
Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient’s individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required.
Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group).
Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97).
Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect
Design, setup and routine operation of a water treatment system for the monitoring of low activities of tritium in water
In the TRITIUM project, an on-site monitoring system is being developed to measure tritium (H) levels in water near nuclear power plants. The quite low-energy betas emitted by H have a very short average path in water (5 μm as shown by simulations for 18 keV electrons). This path would be further reduced by impurities present in the water, resulting in a significant reduction of the detection efficiency. Therefore, one of the essential requirements of the project is the elimination of these impurities through a filtration process and the removal of salts in solution. This paper describes a water treatment system developed for the project that meets the following requirements: the water produced should be of near-pure water quality according to ISO 3696 grade 3 standard (conductivity < 10 μS/cm); the system should operate autonomously and be remotely monitored.This work was supported by the INTERREG-SUDOE EEC program
through the project TRITIUM e SOE1/P4/E0214 entitled: “Dise~no,
construccition y puesta a punto de estaciones automaticas para el
monitoraje en tiempo real de bajos niveles radiactivos de tritio en
aguas
Ação de reguladores vegetais no desenvolvimento, aspectos nutricionais, anatômicos e na produtividade do feijoeiro (Phaseolus vulgaris cv. Carioca)
Pot-grown plants of Phaseolus vulgaris cv. Carioca, under greenhouse conditions, were sprayed with 50ppm of gibberellic acid, 50ppm of naphthaleneacetic acid, 1000ppm of chlormequat, 3000ppm of daminozide, 100ppm of chlorflurenol and 50ppm of Figaron. Gibberellic acid significantly increased plant height and the number of leaves, chlorflurenol decreased these parameters. Daminozide increased K level and presented a tendency to increase N compounds increasing the level of proteic nitrogen. Chlorflurenol increased K and Ca levels, and Figaron also increased Ca content. Histological analysis of changes induced by chlorf lurenol showed an accumulation of starch grains on medullary parenchyma cells of petioles in treated dry beans. The yield of dry beans was inhibited by chlorflurenol and decreased by naphthaleneacetic acid, chlormequat and daminozide.Neste estudo foram determinados os efeitos de reguladores vegetais na altura, na formação foliar, nos teores de nutrientes acumulados (N total, protéico e amínico; P, K e Ca, na anatomia e na produtividade do feijoeiro 'Carioca', sob condições de casa de vegetação. A semeadura foi realizada em 22/07/88, sendo que em 22/08/88 foi efetuada a pulverização das plantas com giberelina 50ppm, ácido naftalenacético 50ppm, chlormequat 1000ppm, daminozide 3000ppm, chlorflurenol 100ppm e Figaron 50ppm, tendo-se mantido um controle. Foram portanto realizados 7 tratamentos, tendo-se estabelecido 7 repetições, num delineamento inteiramente casualizado. A altura das plantas e a formação foliar foram determinadas 7, 14, e 21 dias após a aplicação, sendo que na colheita procedeu-se à coleta de amostras para a análise das diferentes formas de N, do P, K e Ca nas plantas, anatomia foliar, além do estabelecimento da produtividade do feijoeiro 'Carioca'. Os resultados obtidos, revelaram que as plantas tratadas com giberelina, mostraram maior crescimento e aumento no número de folhas desenvolvidas, sendo que chlorflurenol causou a maior redução nesses parâmetros. Daminozide e chlormequat tenderam a apresentar maiores teores de N total, sendo que daminozide através de aumento em N protéico e chlormequat incrementando N amínico. Chlorflurenol aumentou os níveis de K e Ca, reduzindo o teor de P, Figaron aumentou o conteúdo de Ca, sendo que daminozide aumentou o nível de K. Análises histológicas das alterações, induzidas por chlorflurenol, revelaram um acúmulo atípico de grãos de amido, nas células do parênquima medular dos pecíolos dos feijoeiros tratados. Ácido naftalenacético, chlormequat e daminozide reduziram o peso das vagens e das sementes, sendo que chlorflurenol inibiu a produção
Time to culture conversion in smokers with pulmonary tuberculosis
Background and objective. It has been reported that tobacco smoking slows the sterilisation of sputum culture in pulmonary tuberculosis, but the factors that could delay culture conversion in patients who smoke are not known. Our aim is to identify the factors influencing sputum culture conversion in smokers with pulmonary tuberculosis. Methods. Ninety-nine patients with a smoking history and diagnosed with pulmonary tuberculosis were analysed retrospectively. The relationship between sputum culture status at the second month and the following variables: age, gender, pack-years index, comorbid diseases, number acid-fast bacilli (AFB) in sputum smear examination, radiological findings (cavitary, extensive or limited disease), drug susceptibility pattern and initial treatment, was analysed. The Student t-test, chi-square test and logistic regression model with forward stepwise conditional methods were used for statistical analysis. A p value of <0.05 was considered to be statistically significant. Results. Twenty six patients (26.2%): 18 males (22.2%) and 8 females (44%) were sputum culture positive at the end of the second month of treatment. In univariate analysis, culture conversion time was significantly associated with female gender and extensive disease, but in a logistic regression analysis was only correlated with female gender (OR=5.63 95% CI 1.21-20.64-p=0.02). Conclusion. In current smokers with pulmonary tuberculosis, the ‘time to culture’ conversion relates only to the female gender
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