903 resultados para Balances (Weighing instruments)
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If you own property on one of North Carolina’s estuaries, you can use this guide as a tool to learn about the choices you have to control your shoreline erosion and help decide which approach may be right for you. In North Carolina, we make a distinction between waterfront property that is located on the estuary, referred to as estuarine, shoreline, soundfront or riverside property, and waterfront property located directly on the ocean, referred to as oceanfront. Why? State laws and regulations addressing estuarine and oceanfront property, and the available erosion control methods, are quite different. This guide focuses on estuarine property. We’ll introduce you to the six main erosion control options in use in North Carolina and give you information about the out-of-pocket costs and tangible benefits of each option. We’ll also give you information about “hidden” costs and benefits that you may want to factor into your decision-making. You are fortunate to have a piece of estuarine shoreline to call your own, whether it’s your year-round residence or a weekend getaway. And if you’ve noticed some shoreline erosion lately, you’re probably a little concerned. But there are ready solutions.
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Catching methods and ways to improve them have been engaging the attention of fishermen from time immemorial. This was done mostly by trial and error methods, as most of the earlier investigations were primarily directed towards solution of biological problems related to fisheries. In recent years several fisheries laboratories have taken up studies on the working principles of many gears such as trawls, gill nets, round haul nets etc. with the aid of instruments developed for the purpose. The purpose of this article is to review the progress made in this field and in the development of telemetering instruments and continuous data acquisition systems.
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Humans are able to stabilize their movements in environments with unstable dynamics by selectively modifying arm impedance independently of force and torque. We further investigated adaptation to unstable dynamics to determine whether the CNS maintains a constant overall level of stability as the instability of the environmental dynamics is varied. Subjects performed reaching movements in unstable force fields of varying strength, generated by a robotic manipulator. Although the force fields disrupted the initial movements, subjects were able to adapt to the novel dynamics and learned to produce straight trajectories. After adaptation, the endpoint stiffness of the arm was measured at the midpoint of the movement. The stiffness had been selectively modified in the direction of the instability. The stiffness in the stable direction was relatively unchanged from that measured during movements in a null force field prior to exposure to the unstable force field. This impedance modification was achieved without changes in force and torque. The overall stiffness of the arm and environment in the direction of instability was adapted to the force field strength such that it remained equivalent to that of the null force field. This suggests that the CNS attempts both to maintain a minimum level of stability and minimize energy expenditure.
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The paper describes the selection of materials for the reliable operation of oceanographic instruments. For selecting the material, raft immersion tests were carried out for one year. Results of the tests are presented. Comparisons between metals were discussed.
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To reduce the surgical trauma to the patient, minimally invasive surgery is gaining considerable importance since the eighties. More recently, robot assisted minimally invasive surgery was introduced to enhance the surgeon's performance in these procedures. This resulted in an intensive research on the design, fabrication and control of surgical robots over the last decades. A new development in the field of surgical tool manipulators is presented in this article: a flexible manipulator with distributed degrees of freedom powered by microhydraulic actuators. The tool consists of successive flexible segments, each with two bending degrees of freedom. To actuate these compliant segments, dedicated fluidic actuators are incorporated, together with compact hydraulic valves which control the actuator motion. Especially the development of microvalves for this application was challenging, and are the main focus of this paper. The valves distribute the hydraulic power from one common high pressure supply to a series of artificial muscle actuators. Tests show that the angular stroke of the each segment of this medical instrument is 90°. © 2012 Springer Science+Business Media, LLC.
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Cortical neurons receive balanced excitatory and inhibitory synaptic currents. Such a balance could be established and maintained in an experience-dependent manner by synaptic plasticity at inhibitory synapses. We show that this mechanism provides an explanation for the sparse firing patterns observed in response to natural stimuli and fits well with a recently observed interaction of excitatory and inhibitory receptive field plasticity. The introduction of inhibitory plasticity in suitable recurrent networks provides a homeostatic mechanism that leads to asynchronous irregular network states. Further, it can accommodate synaptic memories with activity patterns that become indiscernible from the background state but can be reactivated by external stimuli. Our results suggest an essential role of inhibitory plasticity in the formation and maintenance of functional cortical circuitry.
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Attributing a dollar value to a keyword is an essential part of running any profitable search engine advertising campaign. When an advertiser has complete control over the interaction with and monetization of each user arriving on a given keyword, the value of that term can be accurately tracked. However, in many instances, the advertiser may monetize arrivals indirectly through one or more third parties. In such cases, it is typical for the third party to provide only coarse-grained reporting: rather than report each monetization event, users are aggregated into larger channels and the third party reports aggregate information such as total daily revenue for each channel. Examples of third parties that use channels include Amazon and Google AdSense. In such scenarios, the number of channels is generally much smaller than the number of keywords whose value per click (VPC) we wish to learn. However, the advertiser has flexibility as to how to assign keywords to channels over time. We introduce the channelization problem: how do we adaptively assign keywords to channels over the course of multiple days to quickly obtain accurate VPC estimates of all keywords? We relate this problem to classical results in weighing design, devise new adaptive algorithms for this problem, and quantify the performance of these algorithms experimentally. Our results demonstrate that adaptive weighing designs that exploit statistics of term frequency, variability in VPCs across keywords, and flexible channel assignments over time provide the best estimators of keyword VPCs.
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BACKGROUND: Outcome assessment can support the therapeutic process by providing a way to track symptoms and functionality over time, providing insights to clinicians and patients, as well as offering a common language to discuss patient behavior/functioning. OBJECTIVES: In this article, we examine the patient-based outcome assessment (PBOA) instruments that have been used to determine outcomes in acupuncture clinical research and highlight measures that are feasible, practical, economical, reliable, valid, and responsive to clinical change. The aims of this review were to assess and identify the commonly available PBOA measures, describe a framework for identifying appropriate sets of measures, and address the challenges associated with these measures and acupuncture. Instruments were evaluated in terms of feasibility, practicality, economy, reliability, validity, and responsiveness to clinical change. METHODS: This study was a systematic review. A total of 582 abstracts were reviewed using PubMed (from inception through April 2009). RESULTS: A total of 582 citations were identified. After screening of title/abstract, 212 articles were excluded. From the remaining 370 citations, 258 manuscripts identified explicit PBOA; 112 abstracts did not include any PBOA. The five most common PBOA instruments identified were the Visual Analog Scale, Symptom Diary, Numerical Pain Rating Scales, SF-36, and depression scales such as the Beck Depression Inventory. CONCLUSIONS: The way a questionnaire or scale is administered can have an effect on the outcome. Also, developing and validating outcome measures can be costly and difficult. Therefore, reviewing the literature on existing measures before creating or modifying PBOA instruments can significantly reduce the burden of developing a new measure.
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BACKGROUND: Physical activity self-report instruments in the US have largely been developed for and validated in White samples. Despite calls to validate existing instruments in more diverse samples, relatively few instruments have been validated in US Blacks. Emerging evidence suggests that these instruments may have differential validity in Black populations. PURPOSE: This report reviews and evaluates the validity and reliability of self-reported measures of physical activity in Blacks and makes recommendations for future directions. METHODS: A systematic literature review was conducted to identify published reports with construct or criterion validity evaluated in samples that included Blacks. Studies that reported results separately for Blacks were examined. RESULTS: The review identified 10 instruments validated in nine manuscripts. Criterion validity correlations tended to be low to moderate. No study has compared the validity of multiple instruments in a single sample of Blacks. CONCLUSION: There is a need for efforts validating self-report physical activity instruments in Blacks, particularly those evaluating the relative validity of instruments in a single sample.
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© 2015. American Geophysical Union. All Rights Reserved.The role of surface and advective heat fluxes on buoyancy-driven circulation was examined within a tropical coral reef system. Measurements of local meteorological conditions as well as water temperature and velocity were made at six lagoon locations for 2 months during the austral summer. We found that temperature rather than salinity dominated buoyancy in this system. The data were used to calculate diurnally phase-averaged thermal balances. A one-dimensional momentum balance developed for a portion of the lagoon indicates that the diurnal heating pattern and consistent spatial gradients in surface heat fluxes create a baroclinic pressure gradient that is dynamically important in driving the observed circulation. The baroclinic and barotropic pressure gradients make up 90% of the momentum budget in part of the system; thus, when the baroclinic pressure gradient decreases 20% during the day due to changes in temperature gradient, this substantially changes the circulation, with different flow patterns occurring during night and day. Thermal balances computed across the entire lagoon show that the spatial heating patterns and resulting buoyancy-driven circulation are important in maintaining a persistent advective export of heat from the lagoon and for enhancing ocean-lagoon exchange.
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El productor agropecuario se enfrenta a diversos y nuevos desafíos, no sólo destinados a maximizar su productividad, sino para atenerse a las exigencias generadas por los mercados, sobre temas que atañen al sector productor de alimentos. Entre las exigencias que surgieron, existen aquellas que apuntan al manejo de nutrientes en los establecimientos agropecuarios a fin de reducir los riesgos ambientales que cada tipo de producción genera. La implementación de los balances de nutrientes dentro del sistema productivo es una herramienta que permite a los productores afrontar futuras reglamentaciones ambientales y mejorar su margen de competitividad. Los tambos pastoriles generan un excedente de nitrógeno y fósforo que se distribuye irregularmente en el sistema acumulándose, el de mayor magnitud y posibilidad de reutilización, en la instalación de ordeño (SO). Este trabajo evalúa la disponibilidad de nitrógeno y fósforo en efluentes de tambo, que potencialmente pueden ser reutilizados para fertilizar recursos forrajeros anuales, a partir del cálculo de balances y estableciendo su nivel de transferencia hacia el sector de ordeño, en sistemas de producción de leche de base pastoril en la provincia de Buenos Aires. Los 27 establecimientos encuestados presentan características productivas diferentes siendo representativos de los tambos pastoriles de las 3 cuencas lecheras seleccionadas. En promedio (±desvío estándar), tenían una superficie de 397,55ha (±343,1), con 312VO (±308,91), una producción de 19 litros/VO/día (±3,49), y raciones con 57,29 por ciento (±15,88) de concentrados y conservados. El balance predial (ingresos - egresos de N-P) de nitrógeno (N) fue de 121,5 (±71,8) kg N/ha/año y el de fósforo (P) fue de 18,3 (±11,5) kg P/ha/año, siendo valores similares a los encontrados por estudios europeos y locales. Los balances anuales del rodeo de ordeño (BRO= ingresos por alimentos-egresos por leche de N-P), como indicadores de la excreción de nutrientes, fueron para N de 159,0 (±40,1) kg N/VO/año y para P de 20,8 (±5,8) kg P/VO/año, presentando correlación con modelos que estiman la excreción utilizados internacionalmente. Mediante los BRO y los tiempos de permanencia se pudo determinar una transferencia promedio del 28,8 por ciento (±10,6 por ciento) del total del N y el P excretado por año, hacia el SO. Los sistemas de tratamiento de efluentes, de existir, son muy heterogéneos. Un 59 por ciento contaba con al menos una laguna de tratamiento, aunque no siempre funcionaban correctamente, el 17 por ciento hace un reuso directo del efluente crudo y el 24 por ciento lo desecha sin tratamiento previo, con las implicancias ambientales e higiénico-sanitarias que esto trae aparejado. La calidad de los efluentes fue muy variable, siendo similares a los hallados por otros autores. Los productores generalmente no aportan por fertilizantes la totalidad de N y P requeridos por los cultivos forrajeros anuales. En un 92,6 por ciento de predios, los nutrientes depositados en el SO podrían reemplazar lo provisto por fertilizantes comerciales. Los nutrientes disponibles en SO permitirían fertilizar un promedio de 37,9 ha de maíz para silaje, cubriendo los requerimientos de nitrógeno, con rendimiento promedio para las cuencas (13.000 kg MS/ha), correspondiendo al 78,4 por ciento de las ha sembradas con maíz de los establecimientos. La imposibilidad de recolectar lo depositado en las pistas de alimentación no permite, actualmente, su reutilización. La implementación de prácticas amigables con el ambiente representa hoy en día un desafío para la producción animal, la ventaja es que la solución está en el mismo lugar donde se produce el problema y con una amplia variedad de tecnologías disponibles