937,699 research outputs found

    Social stress, social support, locus of control and depression among middle and high school-aged population

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    The data from a randomly selected sample of 545 middle and high school-aged adolescents across the state of Iowa were studied to examine the means through which social stress is associated with depressive symptoms. Social stress is assumed to be socially determined by unjust social distributions of power and resources that place certain individuals and groups under greatest social pressure and give rise to situations that limit their access to already limited resources, obstruct alternative behavior options, and create unjustified interpersonal tension. Four variables were used to measure social stress: (1) lack of job opportunities, (2) competition in school, (3) gender discrimination in school, and (4) physical abuse. The negative effects of these variables of social stress on adolescents\u27 mental health and well being were hypothesized to be moderated by the buffering effects social support and locus of control. The important findings are: (1) Lack of job opportunities, competition and physical abuse have significant positive effects on depression. (2) Social support and locus of control have significant negative effects on depression. (3) The moderating effects of social support and locus of control between depression and the variables of social stress are found to be significant. (4) There are significant gender differences between boys and girls. Lack of job opportunities and competition in school are more important in predicting depression for boys. Gender discrimination in school, physical abuse, and locus of control are more important in predicting depression for girls. (5) The proposed structural equation model explains more variance of depression for girls than for boys

    L4: Water Governance in the Limpopo Basin

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    The project focuses on access and control of water/land, and the associated management and governance mechanisms. L4 seeks to provide the people and governments of the Limpopo Basin with: 1. A package of ways to better understand and organise access rights to water for multiple uses from farm level to the basin and regional level, 2. A package of ways to organise technologies for different physical and socio-economic contexts so as to improve the management and control of water for multiple uses from one or more water sources, 3. A suite of policy and legal options to support agriculture-based livelihoods in which water plays a vital role, and 4. A set of institutional arrangements that is appropriate for different classes of smallholder farmers including the resource poor, women farmers, and other disadvantaged groups. The issues that have been raised above encompass the full water cycle, which makes it important to consider at the same time management of rainwater (for rainfed agriculture and rainfed pasture, for example) – the green water component – alongside the better management of runoff, groundwater and stored surface water - the blue water component. This has important social and institutional implications – and also policy and legal implications, as southern Africa moves from the management of shared flowing water to the management of rainfall across the shared basins such as the Limpopo (Ncube et al, 2009)

    L4: Water Governance in the Limpopo Basin

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    The project focuses on access and control of water/land, and the associated management and governance mechanisms. L4 seeks to provide the people and governments of the Limpopo Basin with: 1. A package of ways to better understand and organise access rights to water for multiple uses from farm level to the basin and regional level, 2. A package of ways to organise technologies for different physical and socio-economic contexts so as to improve the management and control of water for multiple uses from one or more water sources, 3. A suite of policy and legal options to support agriculture-based livelihoods in which water plays a vital role, and 4. A set of institutional arrangements that is appropriate for different classes of smallholder farmers including the resource poor, women farmers, and other disadvantaged groups. The issues that have been raised above encompass the full water cycle, which makes it important to consider at the same time management of rainwater (for rainfed agriculture and rainfed pasture, for example) – the green water component – alongside the better management of runoff, groundwater and stored surface water - the blue water component. This has important social and institutional implications – and also policy and legal implications, as southern Africa moves from the management of shared flowing water to the management of rainfall across the shared basins such as the Limpopo (Ncube et al, 2009)

    Multidimensional individualised Physical ACTivity (Mi-PACT) - a technology-enabled intervention to promote physical activity in primary care: Study protocol for a randomised controlled trial

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    © 2015 Peacock et al. Background: Low physical activity is a major public health problem. New cost-effective approaches that stimulate meaningful long-term changes in physical activity are required, especially within primary care settings. It is becoming clear that there are various dimensions to physical activity with independent health benefits. Advances in technology mean that it is now possible to generate multidimensional physical activity 'profiles' that provide a more complete representation of physical activity and offer a variety of options that can be tailored to the individual. Mi-PACT is a randomised controlled trial designed to examine whether personalised multidimensional physical activity feedback and self-monitoring alongside trainer-supportive sessions increases physical activity and improves health outcomes in at-risk men and women. Methods/Design: We aim to recruit 216 patients from within primary care aged 40 to 70years and at medium or high risk of cardiovascular disease and/or type II diabetes mellitus. Adopting an unequal allocation ratio (intervention: control) of 2:1, participants will be randomised to one of two groups, usual care or the intervention. The control group will receive usual care from their general practitioner (GP) and standardised messages about physical activity for health. The intervention group will receive physical activity monitors and access to a web-based platform for a 3-month period to enable self-monitoring and the provision of personalised feedback regarding the multidimensional nature of physical activity. In addition, this technology-enabled feedback will be discussed with participants on 5 occasions during supportive one-to-one coaching sessions across the 3-month intervention. The primary outcome measure is physical activity, which will be directly assessed using activity monitors for a 7-day period at baseline, post intervention and at 12months. Secondary measures (at these time-points) include weight loss, fat mass, and markers of metabolic control, motivation and well-being. Discussion: Results from this study will provide insight into the effects of integrated physical activity profiling and self-monitoring combined with in-person support on physical activity and health outcomes in patients at risk of future chronic disease. Trial registration:ISRCTN18008011Trial registration date: 31 July 201

    Air Transport versus High-Speed Rail: From Physics to Economics

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    Purpose - This bachelor thesis compares high-speed rail (HSR) transport with air transport. The investigation considers physical fundamentals, energy consumption, environmental impact, infrastructure and investment, market situations, passenger's selection criteria to choose transportation options, and overall economics. --- Methodology - The thesis combines an investigation of physical principles with a literature review. --- Findings - Steel wheels on steel rails show by far less rolling resistance to support the train's weight than drag due to lift (induced drag) to support the aircraft's weight. This leads to less energy consumption. HSR trains use electricity from an overhead line. Hence, the environmental impact of HSR also depends much on how the electricity is produced. Airplanes only need an air traffic control environment to connect airports. In contrast, HSR needs infrastructure to connect stations. The amount of necessary infrastructure depends on the geological conditions. For example, crossing mountains means high investment. Longer passages over water are infeasible for HSR. High-speed rail is superior to air transport when connecting megacities because the trains have higher transport capacity, offer higher service frequencies and mission reliability, shorter total travel time, shorter access time to stations, shorter unproductive waiting time in stations and potentially lower travel costs. HSR is a strong competitor to airline services and has replaced some short range flights. A comparison of HSR in different world regions shows differences in the market situation and in passenger's selection criteria for transportation options. --- Research limitations - The potential of high-speed rail was investigated mainly on busy routes with high service frequencies. A comprehensive network comparison between high-speed trains and airplanes was not done and could lead to somewhat different results. --- Practical implications - The report tries to contribute arguments to the discussion about alternatives to air travel. --- Social implications - With more knowledge people can make an educated choice between transport options, can vote with their feet, and can take a firm position in the public discussion. --- Originality/value - A general comparison of HSR and air transport from physical fundamentals to economics seemed to be missing

    Refining low-volume, high-concentration herbicide applications to control Chromolaena odorata (L.) King & Robinson (Siam weed) in remote areas

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    Chromolaena odorata (L.) King and Robinson (Siam weed) is a highly invasive plant and a high priority for control in north Queensland. It can be effectively treated using high-volume, groundbased herbicide spray equipment, but operational information shows that this control method becomes increasingly difficult in areas where vehicle access is prevented by rougher terrain. Low-volume, high-concentration herbicide applications have proven capable of causing high mortality in these remote situations. Two trials were undertaken between May 2010 and May 2012 to refine effective rates of aminopyralid/fluroxypyr, fluroxypyr and metsulfuron-methyl, only using low-volume, high-concentration applications on Siam weed. Fluroxypyr on its own was as effective as aminopyralid/fluroxypyr as both herbicides caused 95-100% mortality at overlapping rates containing 5 to 18.85 g a.i. L-1 of fluroxypyr. Metsulfuron-methyl caused 100% mortality when applied at 3 and 6 g a.i. L-1. Effective control was achieved with approximately 16 to 22 mL of the solutions per plant, so a 5 L mixture in a backpack could treat 170 to 310 adult plants. There are several options for treating Siam weed on the ground and the choice of methods reflects the area, plant density and accessibility of the infestation. Control information from Siam weed field crews shows that low volume, high concentration herbicide applications applied using a splatter gun are a more efficient method for controlling larger, denser remote infestations than physical removal. By identifying effective herbicides that are applied through low-volume equipment, these trials provide an additional and more efficient tool for controlling Siam weed in remote areas

    Refining low-volume, high-concentration herbicide applications to control Chromolaena odorata (L.) King & Robinson (Siam weed) in remote areas

    Get PDF
    Chromolaena odorata (L.) King and Robinson (Siam weed) is a highly invasive plant and a high priority for control in north Queensland. It can be effectively treated using high-volume, groundbased herbicide spray equipment, but operational information shows that this control method becomes increasingly difficult in areas where vehicle access is prevented by rougher terrain. Low-volume, high-concentration herbicide applications have proven capable of causing high mortality in these remote situations. Two trials were undertaken between May 2010 and May 2012 to refine effective rates of aminopyralid/fluroxypyr, fluroxypyr and metsulfuron-methyl, only using low-volume, high-concentration applications on Siam weed. Fluroxypyr on its own was as effective as aminopyralid/fluroxypyr as both herbicides caused 95-100% mortality at overlapping rates containing 5 to 18.85 g a.i. L-1 of fluroxypyr. Metsulfuron-methyl caused 100% mortality when applied at 3 and 6 g a.i. L-1. Effective control was achieved with approximately 16 to 22 mL of the solutions per plant, so a 5 L mixture in a backpack could treat 170 to 310 adult plants. There are several options for treating Siam weed on the ground and the choice of methods reflects the area, plant density and accessibility of the infestation. Control information from Siam weed field crews shows that low volume, high concentration herbicide applications applied using a splatter gun are a more efficient method for controlling larger, denser remote infestations than physical removal. By identifying effective herbicides that are applied through low-volume equipment, these trials provide an additional and more efficient tool for controlling Siam weed in remote areas

    Millimeter Wave Cellular Networks: A MAC Layer Perspective

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    The millimeter wave (mmWave) frequency band is seen as a key enabler of multi-gigabit wireless access in future cellular networks. In order to overcome the propagation challenges, mmWave systems use a large number of antenna elements both at the base station and at the user equipment, which lead to high directivity gains, fully-directional communications, and possible noise-limited operations. The fundamental differences between mmWave networks and traditional ones challenge the classical design constraints, objectives, and available degrees of freedom. This paper addresses the implications that highly directional communication has on the design of an efficient medium access control (MAC) layer. The paper discusses key MAC layer issues, such as synchronization, random access, handover, channelization, interference management, scheduling, and association. The paper provides an integrated view on MAC layer issues for cellular networks, identifies new challenges and tradeoffs, and provides novel insights and solution approaches.Comment: 21 pages, 9 figures, 2 tables, to appear in IEEE Transactions on Communication

    Review of best management practices for aquatic vegetation control in stormwater ponds, wetlands, and lakes

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    Auckland Council (AC) is responsible for the development and operation of a stormwater network across the region to avert risks to citizens and the environment. Within this stormwater network, aquatic vegetation (including plants, unicellular and filamentous algae) can have both a positive and negative role in stormwater management and water quality treatment. The situations where management is needed to control aquatic vegetation are not always clear, and an inability to identify effective, feasible and economical control options may constrain management initiatives. AC (Infrastructure and Technical Services, Stormwater) commissioned this technical report to provide information for decision- making on aquatic vegetation management with in stormwater systems that are likely to experience vegetation-related issues. Information was collated from a comprehensive literature review, augmented by knowledge held by the authors. This review identified a wide range of management practices that could be potentially employed. It also demonstrated complexities and uncertainties relating to these options that makes the identification of a best management practice difficult. Hence, the focus of this report was to enable users to screen for potential options, and use reference material provided on each option to confirm the best practice to employ for each situation. The report identifies factors to define whether there is an aquatic vegetation problem (Section 3.0), and emphasises the need for agreed management goals for control (e.g. reduction, mitigation, containment, eradication). Resources to screen which management option(s) to employ are provided (Section 4.0), relating to the target aquatic vegetation, likely applicability of options to the system being managed, indicative cost, and ease of implementation. Initial screening allows users to shortlist potential control options for further reference (Section 5.0). Thirty-five control options are described (Section 5.0) in sufficient detail to consider applicability to individual sites and species. These options are grouped under categories of biological, chemical or physical control. Biological control options involve the use of organisms to predate, infect or control vegetation growth (e.g. classical biological control) or manipulate conditions to control algal growth (e.g. pest fish removal, microbial products). Chemical control options involve the use of pesticides and chemicals (e.g. glyphosate, diquat), or the use of flocculants and nutrient inactivation products that are used to reduce nutrient loading, thereby decreasing algal growth. Physical control options involve removing vegetation or algal biomass (e.g. mechanical or manual harvesting), or setting up barriers to their growth (e.g. shading, bottom lining, sediment capping). Preventative management options are usually the most cost effective, and these are also briefly described (Section 6.0). For example, the use of hygiene or quarantine protocols can reduce weed introductions or spread. Catchment- based practices to reduce sediment and nutrient sources to stormwater are likely to assist in the avoidance of algal and possibly aquatic plant problems. Nutrient removal may be a co-benefit where harvesting of submerged weed biomass is undertaken in stormwater systems. It should also be considered that removal of substantial amounts of submerged vegetation may result in a sudden and difficult-to-reverse s witch to a turbid, phytoplankton dominated state. Another possible solution is the conversion of systems that experience aquatic vegetation issues, to systems that are less likely to experience issues. The focus of this report is on systems that receive significant stormwater inputs, i.e. constructed bodies, including ponds, amenity lakes, wetlands, and highly-modified receiving bodies. However, some information will have application to other natural water bodies

    Promoting Healthy Communities and Reducing Childhood Obesity: Legislative Options

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    Summarizes legislation proposed or enacted in 2007-08 in the areas of healthy eating and physical activity such as nutrition, physical education, and obesity prevention and treatment, as well as healthy community design and access to healthy food
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