4,352 research outputs found

    Assessment of the Feasibility of Permeable Pavement for Sustainable Stormwater Management Using SWMM

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    The advancement of urbanization in the Philippines changed natural lands into impervious surfaces and aided the contamination of surface runoff and nearby water bodies. Low Impact Development (LID) technologies were introduced as an alternative to conventional drainage systems, specifically permeable pavements. Such technology is beneficial for stormwater runoff reduction, ground infiltration enablement, and stormwater treatment. This research was conducted to investigate the feasibility of permeable pavement for sustainable stormwater management in a university setting, particularly in De La Salle University – Laguna Campus. The Storm Water Management Model (SWMM) was utilized to simulate different rainfall scenarios on selected little to no vegetation regions with increasing permeable pavement area coverage. The findings showed that the LID surface area to subcatchment area (SA/CA) ratio is inversely proportional to the total runoff reduction observed in all rainfall scenarios. The total runoff reached zero when the SA/CA ratio was at least 50%. The permeable pavement was concluded to be effective in surface runoff infiltration, reduction, and storage which is beneficial for long-term stormwater management and flood prevention strategies. The study can be used in future investigations and applications of similar LID technologies

    143±165 * Corresponding author

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    Abstract Parent material and pumiceous alluvial soils, located in a tropical region of Mexico, were studied to supply information on soil suitability for agricultural production in the context of sustainable agriculture. In recent alluvial soils, an understanding of how soil characteristics vary with parent material and topography provides a basis for determining land utilization type, land suitability as well as land quality. The main objective of this study was to establish the relationship of soil properties to parent material in west Nayarit, Mexico. Field studies were initiated in 1993 by a request for technical assistance from the Comision Federal de Electricidad. The studied soils were derived from pumice that has been reworked and mixed with detrital material from other sources. We found that such soils have unique physical, chemical and mineralogical characteristics that are rarely found in soils derived from other parent materials. Data for two selected alluvial soil pro®les are presented. These soils were developed on Holocene volcanogenic pumiceous alluvial river terraces and river¯oodplains, under current udicisohyperthermic soil-climate conditions. The agronomic properties, tillage in¯uences and fertilizer requirements of these soils have been studied extensively. To maximize their productivity and minimize deterioration, proper management must be based on an understanding of the unique physical, chemical and mineralogical properties. Results indicate that such soils have physical properties that provide a good environment for deep rooting and can supply the water necessary for vigorous plant growth. In both soils, water retention at 33 and 1500 kPa, particle surface area, calculated clay, cation exchange capacity, Al exchangeable percentage and P retention, and the occurrence of isotropic coatings on rock fragments and peds tend to increase in the presence of the large amounts of hydrolyzed pumice that are found in the 0.02±2.0 mm fraction. Scanning electron microscope±energy dispersive X-ray analyses demonstrate that the coatings dominantly consist of noncrystalline material, probably allophanic-like material as suggested by the Si/Al molar ratio of 1.0. Selective dissolution analysis reveals that these abundant noncrystalline materials consist of ferrihydrite and allophane with an atomic ratio (Al o ÀAl p )/Si o of approximately 1.4. Both ferrihydrite and allophane have very large speci®c surface area and absorptive capacity that make a signi®cant contribution to the overall properties of these soils. X-ray diffraction analysis and transmission electron microscope observation show that the major group of crystalline clay minerals in the upper section of studied soils are tubular and spheroidal halloysite. These soils were classi®ed as Vitrandic Udi¯uvents according to Soil Taxonomy. # 2000 Elsevier Science B.V. All rights reserved

    AISLAMIENTO DE ADN GENÓMICO DE Myrciaria dubia (HBK) “CAMU CAMU” APROPIADO PARA ANÁLISIS MOLECULARES

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    Myrciaria dubia “camu-camu”, una especie nativa de la Amazonía que produce frutos con alto contenido de vitamina C y otras sustancias importantes. Sin embargo, los estudios moleculares de esta planta son escasos, por falta de un protocolo reproducible para purificar sus ácidos nucléicos. El objetivo de este trabajo fue establecer un protocolo para aislar el ADN genómico a partir de hojas de M. dubia, apropiado para análisis moleculares. El ADN se purificó con un protocolo modificado, la calidad y cantidad se estimó por espectrofotometría y electroforesis en gel de agarosa. Adicionalmente, la calidad se evaluó mediante RAPD. El ratio de calidad (A260/A280) promedio del ADN fue 1.9±0.1 y el espectro de absorción UV/Vis presentó un único pico de máxima absorbancia a 260nm. Mediante electroforesis el ADN fue íntegro y sin ARN. También, la síntesis de amplicones RAPD nos sugiere ausencia de inhibidores para polimerasas. La concentración promedio del ADN fue 99±33 ng/ml y el rendimiento promedio fue 237±80 mg ADN/g hoja. En conclusión, se ha establecido un protocolo de aislamiento de ADN genómico a partir de hojas de Myrciaria dubia “camu camu”, caracterizado por permitirnos obtener ADN de alta calidad y cantidad suficiente para análisis moleculares como el RAPD

    Cyclic Density Functional Theory : A route to the first principles simulation of bending in nanostructures

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    We formulate and implement Cyclic Density Functional Theory (Cyclic DFT) -- a self-consistent first principles simulation method for nanostructures with cyclic symmetries. Using arguments based on Group Representation Theory, we rigorously demonstrate that the Kohn-Sham eigenvalue problem for such systems can be reduced to a fundamental domain (or cyclic unit cell) augmented with cyclic-Bloch boundary conditions. Analogously, the equations of electrostatics appearing in Kohn-Sham theory can be reduced to the fundamental domain augmented with cyclic boundary conditions. By making use of this symmetry cell reduction, we show that the electronic ground-state energy and the Hellmann-Feynman forces on the atoms can be calculated using quantities defined over the fundamental domain. We develop a symmetry-adapted finite-difference discretization scheme to obtain a fully functional numerical realization of the proposed approach. We verify that our formulation and implementation of Cyclic DFT is both accurate and efficient through selected examples. The connection of cyclic symmetries with uniform bending deformations provides an elegant route to the ab-initio study of bending in nanostructures using Cyclic DFT. As a demonstration of this capability, we simulate the uniform bending of a silicene nanoribbon and obtain its energy-curvature relationship from first principles. A self-consistent ab-initio simulation of this nature is unprecedented and well outside the scope of any other systematic first principles method in existence. Our simulations reveal that the bending stiffness of the silicene nanoribbon is intermediate between that of graphene and molybdenum disulphide. We describe several future avenues and applications of Cyclic DFT, including its extension to the study of non-uniform bending deformations and its possible use in the study of the nanoscale flexoelectric effect.Comment: Version 3 of the manuscript, Accepted for publication in Journal of the Mechanics and Physics of Solids, http://www.sciencedirect.com/science/article/pii/S002250961630368

    The Effects of Cocaine on Different Redox Forms of Cysteine and Homocysteine, and on Labile, Reduced Sulfur in the Rat Plasma Following Active versus Passive Drug Injections

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    Received: 28 November 2012 / Revised: 19 April 2013 / Accepted: 6 May 2013 / Published online: 16 May 2013 The Author(s) 2013. This article is published with open access at Springerlink.comThe aim of the present studies was to evaluate cocaine-induced changes in the concentrations of different redox forms of cysteine (Cys) and homocysteine (Hcy), and products of anaerobic Cys metabolism, i.e., labile, reduced sulfur (LS) in the rat plasma. The above-mentioned parameters were determined after i.p. acute and subchronic cocaine treatment as well as following i.v. cocaine self-administration using the yoked procedure. Additionally, Cys, Hcy, and LS levels were measured during the 10-day extinction training in rats that underwent i.v. cocaine administration. Acute i.p. cocaine treatment increased the total and protein-bound Hcy contents, decreased LS, and did not change the concentrations of Cys fractions in the rat plasma. In turn, subchronic i.p. cocaine administration significantly increased free Hcy and lowered the total and protein-bound Cys concentrations while LS level was unchanged. Cocaine self-administration enhanced the total and protein-bound Hcy levels, decreased LS content, and did not affect the Cys fractions. On the other hand, yoked cocaine infusions did not alter the concentration of Hcy fractions while decreased the total and protein-bound Cys and LS content. This extinction training resulted in the lack of changes in the examined parameters in rats with a history of cocaine self-administration while in the yoked cocaine group an increase in the plasma free Cys fraction and LS was seen. Our results demonstrate for the first time that cocaine does evoke significant changes in homeostasis of thiol amino acids Cys and Hcy, and in some products of anaerobic Cys metabolism, which are dependent on the way of cocaine administration

    Response variability and adaptive process in motor learning

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    daptativo em aprendizagem motora. Trinta e duas estudantes universitárias foram aleatoriamente divididas em dois grupos, GC e GE, tendo executado 25 tentativas na fase de estabilização e 20 tentativas na fase de adaptação. O GC foi submetido à prática de resposta constante e o GE à prática de resposta variada, numa tarefa de coordenação bi-manual. As medidas utilizadas foram o tempo de execução das tentativas e o número de erros. A análise de variância a dois fatores (2 grupos x 5 blocos) com medidas repetidas no segundo fator indicou que em relação ao erro houve efeito de aprendizagem no GC e em relação ao tempo de execução houve efeito de aprendizagem nos dois grupos. A comparação inter-grupos mostrou que não houve diferença significante em relação às duas medidas na fase de adaptação. Entretanto, o teste t aplicado para comparar a última tentativa da fase de estabilização e a primeira da fase de adaptação mostrou que o GC teve maior dificuldade em adaptar-se à nova situação o que, dentro dos limites, foi interpretado como evidência favorável à hipótese formuladaThe present study’s purpose was to investigate the effect of response variability in the adaptive process of motor learning. Thirty two female undergraduate students were randomly divide in o groups, an EG, and performed twenty five trials in the stabilization phase and twenty in e a ap a on p e. The CG was submitted to constant response practice condition and the EG to e van response practice condition, using the two-hand coordination task. Measures used were tn execu on ime an number of errors. Two-way analysis of variance with repeated measures m the secon a or s owe learning effect in relation to error in the CG and the same effect in relation to trials execution ime in both groups. An inter-groups comparison showed no significant difference in relation to o measures in the adaptation phase, but the comparison between the stabilization phase last trial and a ptation p e first trial by t test showed that the CG had more difficulty in adapting to the new situation. This result was interpreted, considered the limitations, as evidence supporting the formulated hypothesi

    Quantitative effects of tobacco smoking exposure on the maternal-fetal circulation

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    <p>Abstract</p> <p>Background</p> <p>Despite the existence of various published studies regarding the effects of tobacco smoking on pregnancy, and especially in regards to placental blood flow and vascular resistance, some points still require clarification. In addition, the amount of damage due to tobacco smoking exposure that occurs has not been quantified by objective means. In this study, we looked for a possible association between flow resistance indices of several arteries and the levels of urinary cotinine and the concentration of carbon monoxide in the exhaled air (COex) of both smoking and non-smoking pregnant women. We also looked for a relationship between those findings and fetal growth and birth weight.</p> <p>Methods</p> <p>In a prospective design, thirty pregnant smokers and thirty-four pregnant non-smokers were studied. The volunteers signed consent forms, completed a self-applied questionnaire and were subjected to Doppler velocimetry. Tobacco smoking exposure was quantified by subject provided information and confirmed by the measurement of urinary cotinine levels and by the concentration of carbon monoxide in the exhaled air (COex). The weight of newborns was evaluated immediately after birth.</p> <p>Results</p> <p>Comparing smoking to non-smoking pregnant women, a significant increase in the resistance index was observed in the uterine arteries (P = 0.001) and umbilical artery (P = 0.001), and a decrease in the middle cerebral artery (P = 0.450). These findings were associated with progressively higher concentrations of COex and urinary cotinine. A decrease in the birth weight was also detected (P < 0.001) in association with a progressive increase in the tobacco exposure of the pregnant woman.</p> <p>Conclusions</p> <p>In pregnant women who smoke, higher arterial resistance indices and lower birth weights were observed, and these findings were associated with increasing levels of tobacco smoking exposure. The values were significantly different when compared to those found in non-smoking pregnant women. This study contributes to the findings that smoking damage during pregnancy is dose-dependent, as demonstrated by the objective methods for measuring tobacco smoking exposure.</p

    Estimativas de ganhos genéticos por diferentes índices de seleção em três populações híbridas de batata.

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    O objetivo deste trabalho foi comparar a eficiência de diferentes índices de seleção de clones superiores de batata. O experimento foi realizado no campo experimental da Embrapa Clima Temperado em Pelotas-RS, na primavera de 2008. Foram estudadas três populações híbridas de batata derivadas de cruzamentos entre clones avançados do programa de melhoramento de batata da Embrapa e cultivares estrangeiras. O delineamento experimental foi blocos aumentados em quatro repetições. O uso de índices de seleção resultou em maiores estimativas de ganhos de seleção, com melhor distribuição entre os caracteres avaliados. Os melhores índices de seleção encontrados para serem utilizados em programas de melhoramento de batata são os índices multiplicativo de Subandi et al. (1973) e o índice baseado na soma de ranks proposto por Mulamba & Mock (1978)
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