Diseño hidráulico de vertedores escalonados con pendientes moderadas: Metodología basada en un estudio experimental

Durante las últimas tres décadas el interés y diversidad en el uso de canales escalonados han aumentado debido al desarrollo de nuevas técnicas y materiales que permiten su construcción de manera rápida y económica (Concreto compactado con rodillo CCR, Gaviones, etc.). Actualmente, los canales escalonados se usan como vertedores y/o canales para peces en presas y diques, como disipadores de energía en canales y ríos, o como aireadores en plantas de tratamiento y torrentes contaminados. Diversos investigadores han estudiado el flujo en vertedores escalonados, enfocándose en estructuras de gran pendiente (  45o) por lo que a la fecha, el comportamiento del flujo sobre vertedores con pendientes moderadas (  15 a 30o) no ha sido totalmente comprendido. El presente artículo comprende un estudio experimental de las propiedades físicas del flujo aire-agua sobre canales escalonados con pendientes moderadas, típicas en presas de materiales sueltos. Un extenso rango de gastos en condiciones de flujo rasante se investigó en dos modelos experimentales a gran escala (Le = 3 a 6): Un canal con pendiente 3.5H:1V (  16o) y dos alturas de escalón distintas (h = 0.1 y 0.05 m) y un canal con pendiente 2.5H:1V (  22o) y una altura de escalón de h = 0.1 m. Los resultados incluyen un análisis detallado de las propiedades del flujo en vertedores escalonados con pendientes moderadas y un nuevo criterio de diseño hidráulico, el cual está basado en los resultados experimentales obtenidos. English abstract: Stepped chutes have been used as hydraulic structures since antiquity, they can be found acting as spillways and fish ladders in dams and weirs, as energy dissipators in artificial channels, gutters and rivers, and as aeration enhancers in water treatment plants and polluted streams. In recent years, new construction techniques and materials (Roller Compacted Concrete RCC, rip-rap gabions, etc.) together with the development of the abovementioned new applications have allowed cheaper construction methods, increasing the interest in stepped chute design. During the last three decades, research in stepped spillways has been very active. However, studies prior to 1993 neglected the effect of free-surface aeration. A number of studies have focused since on steep stepped chutes (  45o) but the hydraulic performance of moderate-slope stepped channels is not yet totally understood. This study details an experimental investigation of physical air-water flow properties down moderate slope stepped spillways conducted in two laboratory models: the first model was a 3.15 m long stepped chute with a 15.9o slope comprising two interchangeable step heights (h = 0.1 m and h = 0.05 m); the second model was a 3.3 m long, stepped channel with a 21.8o slope (h = 0.1 m). A broad range of discharges within transition and skimming flow regimes was investigated. Measurements were conducted using a double tip conductivity probe. The study provides new, original insights into air-water stepped chute flows not foreseen in prior studies and presents a new design criterion for chutes with moderate slopes based on the experimental results.

Career development and systems theory: Connecting theory and practice

The Systems Theory Framework was developed to produce a metatheoretical framework through which the contribution of all theories to our understanding of career behaviour could be recognised. In addition it emphasises the individual as the site for the integration of theory and practice. Its utility has become more broadly acknowledged through its application to a range of cultural groups and settings, qualitative assessment processes, career counselling, and multicultural career counselling. For these reasons, the STF is a very valuable addition to the field of career theory. In viewing the field of career theory as a system, open to changes and developments from within itself and through constantly interrelating with other systems, the STF and this book is adding to the pattern of knowledge and relationships within the career field. The contents of this book will be integrated within the field as representative of a shift in understanding existing relationships within and between theories. In the same way, each reader will integrate the contents of the book within their existing views about the current state of career theory and within their current theory-practice relationship. This book should be required reading for anyone involved in career theory. It is also highly suitable as a text for an advanced career counselling or theory course.

Solid-phase extraction method with high-performance liquid chromatography and electrochemical detection for the quantitative analysis of oxycodone in human plasma

A sensitive and reproducible solid-phase extraction (SPE) method for the quantification of oxycodone in human plasma was developed. Varian Certify SPE cartridges containing both C-8 and benzoic acid functional groups were the most suitable for the extraction of oxycodone and codeine (internal standard), with consistently high (greater than or equal to 80%) and reproducible recoveries. The elution mobile phase consisted of 1.2 ml of butyl chloride-isopropanol (80:20, v/v) containing 2% ammonia. The quantification limit for oxycodone was 5.3 pmol on-column. Within-day and inter-day coefficients of variation were 1.2% and 6.8% respectively for 284 nM oxycodone and 9.5% and 6.2% respectively for 28.4 nM oxycodone using 0.5-ml plasma aliquots. (C) 1998 Elsevier Science BN. All rights reserved.

Inactive Australian college students' preferred activities, sources of assistance, and motivators

Participation in regular physical activity reduces the risk of cardiovascular disease and all-cause mortality as well as providing numerous health benefits.' The steepest decline in physical activity occurs during adolescence (approximately 15 to 18 years of age) and young adulthood (20 to 25 years).(2) Australian population studies have found that levels of physical inactivity are twice as high for those 20 to 29 years old as they are for those under 20 years old.(3,4) As college students move through this period of changing roles within family and peer groups, they may be expected to have specific preferences and expected outcomes for physical activity participation that are different from those they had previously as high school students.(5) Studies of physical activity determinants suggest that while there are some similarities between males and females, there are differences in preferences for specific types of activity.(6) Calfas et al.(5) found that women reported body image factors (weight loss, dissatisfaction with body) to be more motivating, while young men rated strength (muscle gain, muscle tone) and social aspects (organized competition, meeting people) of physical activity more highly than did young women. We examined preferred physical activities, sources of assistance to be more active, and perceived motivators for activity in a sample of inactive college students. Differences between males and females were examined, and the implications for campus-based physical activity promotion strategies are considered.

Relationships between movement initiation times and movement-related cortical potentials in Parkinson's disease

Movement-related cortical potentials recorded from the scalp reveal increasing cortical activity occurring prior to voluntary movement. Studies of set-related cortical activity recorded from single neurones within premotor and supplementary motor areas in monkeys suggest that such premovement activity may act to prime activity of appropriate motor units in readiness to move, thereby facilitating the movement response. Such a role of early stage premovement activity in movement-related cortical potentials was investigated by examining the relationship between premovement cortical activity and movement initiation or reaction times. Parkinson's disease and control subjects performed a simple button-pressing reaction time task and individual movement-related potentials were averaged for responses with short compared with long reaction times. For Parkinson's disease subjects but not for the control subjects, early stage premovement cortical activity was significantly increased in amplitude for faster reaction times, indicating that there is indeed a relationship between premovement cortical activity amplitude and movement initiation or reaction times. In support of studies of set-related cortical activity in monkeys, it is therefore suggested that early stage premovement activity reflects the priming of appropriate motor units of primary motor cortex, thereby reducing movement initiation or reaction times. (C) 1999 Elsevier Science B.V. All rights reserved.

The historiographic Hispano-Americanism: Spain and America in the perspective of Ricardo Levene and Rafael Altamira

This article analyzes how Latin American history was interpreted by two eminent historians, the Argentine Ricardo Levene and the Spaniard Rafael Altamira. It discusses how their paths crossed in the advocacy of Hispano-Americanism as a political project and interpretive horizon of Iberian and American history.

An evaluation of the evidence for linkages between mangroves and fisheries: A synthesis of the literature and identification of research directions

There is a widely held paradigm that mangroves are critical for sustaining production in coastal fisheries through their role as important nursery areas for fisheries species. This paradigm frequently forms the basis for important management decisions on habitat conservation and restoration of mangroves and other coastal wetlands. This paper reviews the current status of the paradigm and synthesises the information on the processes underlying these potential links. In the past, the paradigm has been supported by studies identifying correlations between the areal and linear extent of mangroves and fisheries catch. This paper goes beyond the correlative approach to develop a new framework on which future evaluations can be based. First, the review identifies what type of marine animals are using mangroves and at what life stages. These species can be categorised as estuarine residents, marine-estuarine species and marine stragglers. The marine-estuarine category includes many commercial species that use mangrove habitats as nurseries. The second stage is to determine why these species are using mangroves as nurseries. The three main proposals are that mangroves provide a refuge from predators, high levels of nutrients and shelter from physical disturbances. The recognition of the important attributes of mangrove nurseries then allows an evaluation of how changes in mangroves will affect the associated fauna. Surprisingly few studies have addressed this question. Consequently, it is difficult to predict how changes in any of these mangrove attributes would affect the faunal communities within them and, ultimately, influence the fisheries associated with them. From the information available, it seems likely that reductions in mangrove habitat complexity would reduce the biodiversity and abundance of the associated fauna, and these changes have the potential to cause cascading effects at higher trophic levels with possible consequences for fisheries. Finally, there is a discussion of the data that are currently available on mangrove distribution and fisheries catch, the limitations of these data and how best to use the data to understand mangrove-fisheries links and, ultimately, to optimise habitat and fisheries management. Examples are drawn from two relatively data-rich regions, Moreton Bay (Australia) and Western Peninsular Malaysia, to illustrate the data needs and research requirements for investigating the mangrove-fisheries paradigm. Having reliable and accurate data at appropriate spatial and temporal scales is crucial for mangrove-fisheries investigations. Recommendations are made for improvements to data collection methods that would meet these important criteria. This review provides a framework on which to base future investigations of mangrove-fisheries links, based on an understanding of the underlying processes and the need for rigorous data collection. Without this information, the understanding of the relationship between mangroves and fisheries will remain limited. Future investigations of mangrove-fisheries links must take this into account in order to have a good ecological basis and to provide better information and understanding to both fisheries and conservation managers.

P2X4 receptors interact with both P2X2 and P2X7 receptors in the form of homotrimers

BACKGROUND AND PURPOSE The P2X receptor family consists of seven subunit types - P2X1-P2X7. All but P2X6 are able to assemble as homotrimers. In addition, various subunit permutations have been reported to form heterotrimers. Evidence for heterotrimer formation includes co-localization, co-immunoprecipitation and the generation of receptors with novel functional properties; however, direct structural evidence for heteromer formation, such as chemical cross-linking and single-molecule imaging, is available in only a few cases. Here we examined the nature of the interaction between two pairs of subunits - P2X2 and P2X4, and P2X4 and P2X7. EXPERIMENTAL APPROACH We used several experimental approaches, including in situ proximity ligation, co-immunoprecipitation, co-isolation on affinity beads, chemical cross-linking and atomic force microscopy (AFM) imaging. KEY RESULTS Both pairs of subunits co-localize upon co-transfection, interact intimately within cells, and can be co-immunoprecipitated and co-isolated from cell extracts. Despite this, chemical cross-linking failed to show evidence for heteromer formation. AFM imaging of isolated receptors showed that all three subunits had the propensity to form receptor dimers. This self-association is likely to account for the observed close interaction between the subunit pairs, in the absence of true heteromer formation. CONCLUSIONS AND IMPLICATIONS We conclude that both pairs of receptors interact in the form of distinct homomers. We urge caution in the interpretation of biochemical evidence indicating heteromer formation in other cases.

Investigation of IGF2/ApaI and H19/RsaI polymorphisms in patients with cutaneous melanoma

Objective: The etiology of cutaneous melanoma is complex, involving both heterogeneous genetic and environmental components. The aim of our study was to verify if single polymorphic sites within IGF2 and H19 genes and their consequent haplotypes influence risk and/or prognosis of familial melanoma. Design: Twenty one patients with clinical criteria of hereditary melanoma (early onset, presence of multiple primary melanoma, and/or one or more affected first- or second-degree relatives) and previously screened for CDKN2A mutations were genotyped by IGF2/ApaI and H19/RsaI PCR-RFLPs. Data were compared between patients and a control group (100 healthy young individuals) using Chi-square and Fisher`s exact tests. We also investigated if these polymorphic sites could be microRNAs potential targets, using RegRNA software. Results: Although the IGF2 and HI9 genotypes/haplotypes were not significantly associated with melanoma, two of the most severe cases (very early onset or multiple melanomas) showed to be heterozygous for both genes. We found an overlap between IGF2/ApaI and miR-615-5p, and between H19/RsaI and miR-574-3p. Conclusions: Some studies have shown H19, and IGF2 genes (or related genes or protein, for example, IGF2R and IMP-3) differential expression in melanoma. However, no study has attempted to examine markers across this cluster in relation to melanoma until now. Since the base change may impair the pairing of microRNA and its binding site, our results suggest a new window for future studies of IGF2 and H19 genetic variability and posttranscriptional regulation. Due to the importance and based on the present results, we suggest that the genotype/haplotype analysis of IGF2 and H19 polymorphisms should be better investigated in large populations with cutaneous melanoma, attempting to tie the association with progression of the disease. (C) 2010 Growth Hormone Research Society. Published by Elsevier Ltd. All rights reserved.

Globalisation and the technology gap: Regional and time evidence

This chapter examines the relationship between globalisation and technological progress. It computes an annual and country specific measure of technological gap, the technology ratio (TGR), using a recently proposed method known as metafrontiers. The TGR is measured as the distance from a group frontier to the global (or meta) frontier. The TGRs provide a measure to compare technological capability across countries. The ranking obtained from the metafrontiers method is first compared to other methods based on the direct measure of patents, science articles, schooling etc. The TGRs are then related to levels of trade openness and inbound and outbound foreign direct investment within regions and overtime in an effort to identify the relationship between technological gap and outward orientation.

Low genetic diversities of rabies virus populations within different hosts in Brazil

The low rates of nonsynonymous evolution observed in natural rabies virus (RABV) isolates are suggested to have arisen in association with the structural and functional constraints operating on the virus protein and the infection strategies employed by RABV within infected hosts to avoid strong selection by the immune response. In order to investigate the relationship between the genetic characteristics of RABV populations within hosts and the virus evolution, the present study examined the genetic heterogeneities of RABV populations within naturally infected dogs and foxes in Brazil, as well as those of bat RABV populations that were passaged once in suckling mice. Sequence analyses of complete RABV glycoprotein (G) genes showed that RABV populations within infected hosts were genetically highly homogeneous whether they were infected naturally or experimentally (nucleotide diversities of 0-0.95 x 10(-3)). In addition, amino acid mutations were randomly distributed over the entire region of the G protein, and the nonsynonymous/synonymous rate ratios (d(N)/d(S)) for the G protein gene were less than 1. These findings suggest that the low genetic diversities of RABV populations within hosts reflect the stabilizing selection operating on the virus, the infection strategies of the virus, and eventually, the evolutionary patterns of the virus. (C) 2009 Elsevier B.V. All rights reserved.

Estimating Income Inequality in China Using Grouped Data and the Generalized Beta Distribution

There are two main types of data sources of income distributions in China: household survey data and grouped data. Household survey data are typically available for isolated years and individual provinces. In comparison, aggregate or grouped data are typically available more frequently and usually have national coverage. In principle, grouped data allow investigation of the change of inequality over longer, continuous periods of time, and the identification of patterns of inequality across broader regions. Nevertheless, a major limitation of grouped data is that only mean (average) income and income shares of quintile or decile groups of the population are reported. Directly using grouped data reported in this format is equivalent to assuming that all individuals in a quintile or decile group have the same income. This potentially distorts the estimate of inequality within each region. The aim of this paper is to apply an improved econometric method designed to use grouped data to study income inequality in China. A generalized beta distribution is employed to model income inequality in China at various levels and periods of time. The generalized beta distribution is more general and flexible than the lognormal distribution that has been used in past research, and also relaxes the assumption of a uniform distribution of income within quintile and decile groups of populations. The paper studies the nature and extent of inequality in rural and urban China over the period 1978 to 2002. Income inequality in the whole of China is then modeled using a mixture of province-specific distributions. The estimated results are used to study the trends in national inequality, and to discuss the empirical findings in the light of economic reforms, regional policies, and globalization of the Chinese economy.

Serotonergic neurons in the nucleus raphe obscurus contribute to interaction between central and peripheral ventilatory responses to hypercapnia

Serotonergic (5-HT) neurons in the nucleus raphe obscurus (ROb) are involved in the respiratory control network. However, it is not known whether ROb 5-HT neurons play a role in the functional interdependence between central and peripheral chemoreceptors. Therefore, we investigated the role of ROb 5-HT neurons in the ventilatory responses to CO(2) and their putative involvement in the central-peripheral CO(2) chemoreceptor interaction in unanaesthetised rats. We used a chemical lesion specific for 5-HT neurons (anti-SERT-SAP) of the ROb in animals with the carotid body (CB) intact or removed (CBR). Pulmonary ventilation (V (E)), body temperature and the arterial blood gases were measured before, during and after a hypercapnic challenge (7% CO(2)). The lesion of ROb 5-HT neurons alone (CB intact) or the lesion of 5-HT neurons of ROb+CBR did not affect baseline V (E) during normocapnic condition. Killing ROb 5-HT neurons (CB intact) significantly decreased the ventilatory response to hypercapnia (p < 0.05). The reduction in CO(2) sensitivity was approximately 15%. When ROb 5-HT neurons lesion was combined with CBR (anti-SERT-SAP+CBR), the V (E) response to hypercapnia was further decreased (-31.2%) compared to the control group. The attenuation of CO(2) sensitivity was approximately 30%, and it was more pronounced than the sum of the individual effects of central (ROb lesion; -12.3%) or peripheral (CBR; -5.5%) treatments. Our data indicate that ROb 5-HT neurons play an important role in the CO(2) drive to breathing and may act as an important element in the central-peripheral chemoreception interaction to CO(2) responsiveness.

Communication and health beliefs - Mass and interpersonal influences on perceptions of risk to self and others

This study investigated the impact of media coverage of a health issue (skin cancer) on judgements of risk to self and others and the role of related communication processes. Consistent with predictions derived from the impersonal impact hypothesis, the effects of mass communication were more evident in perceptions of risk to others rather than in perceptions of personal risk. Perceptions of personal risk were more strongly correlated with interpersonal communication. However, as suggested by media system dependency theory, the relationship between mass communication and beliefs was complex. The impact of mass communication on both personal and impersonal perceptions was bound to be moderated by self-reported dependence on mass mediated information. The effect of this two-way interaction 071 perceptions of personal risk was partially mediated through interpersonal communication. Results point to the interdependence of mass and interpersonal communication as sources of social influence and the role of media dependency in shaping media impact.

The Winnipeg principles, WTO and sustainable development: Proposed policies for reconciling trade and the environment

There is, a widespread belief that the WTO has made virtually no concessions to environmentalists about their concerns arising from free trade and the process of globalization. There are concerns that these processes may undermine prospects for sustainable development. Following, the United Nations Conference on Environment and Development held in Rio de Janeiro in 1992, the International Institute for Sustainable Development was established to advocate policies to support sustainable development within Canada and globally. In 1994, it proposed the Winnipeg Principles as. a means for reconciling international trade and development so as to: achieve sustainable development (ISD, 1994a,b). These seven principles are outlined in this article and assessed:. Although the International Institute for Sustainable Development had hoped: through these principles to influence the work programme of the Environment and Trade Committee of WTO, it seems to have little effect. Probably if these principles had been seriously considered by WTO, the serious social conflicts which emerged globally at the beginning of this century would have been avoided, and we would be in a better position to understand the complex links between trade, environment and sustainable development and adopt relevant policies. Copyright (C) 2001 John Wiley & Sons, Ltd and ERP Environment.