2,125 research outputs found

    Design and Field Monitoring of 70 Foot High Tied Anchor Retaining Wall

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    Temporary tied anchor retaining walls have been used extensively where deep excavations are required. However, permanent tied anchor retaining walls to provide lateral support along one side of a multi-story building are seldom utilized. The wall was monitored for deflection and tie load changes during and after construction. A partial detensioning program was instituted in order to maintain the design stresses

    Dietary effect of Quillaja saponaria and/or Yucca schidigera extract on growth and survival of common carp Cyprinus carpio, their antioxidant capacity and metabolic response to hypoxic condition

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    This study evaluated dietary effects of extracts of Quillay Quillaja saponaria, and/or Yucca Yucca schidigera on growth and survival of juvenile common carp Cyprinus carpio, and their antioxidant capacity and metabolic response to low dissolved oxygen (DO) stress. For 8 weeks, fish were fed one of 4 different diets. The diets were supplemented with either 150 mg/kg Quillay (QS), 150 mg/kg Yucca (YS), the combination of 75 mg/kg Quillay and 75 mg/kg Yucca (M), or control diet (C) without addition of Quillay or Yucca. Growth and survival were monitored periodically. After rearing, fish were subjected to low DO stress, and after a week, antioxidant capacity (superoxide dismutase, glutathione peroxidase and glutathione reductase) and metabolic response (glucose, triglycerides and lactate) were analyzed. QSfed fish had the highest weight gain among all the treatments. Treatments did not affect fish survival a week after low DO stress. Among antioxidant capacity and metabolic response, significant effects were found only on superoxide dismutase and glucose. QS fed fish had 39% lower plasma superoxide dismutase than the C and M groups. QS and M groups exhibited 29% and 26% lower plasma glucose than the C group, respectively. Overall, the QS diet improved growth and exhibited favorable antioxidant capacity and metabolic response of carp to low dissolved oxygen environment

    Shape Synthesis in Mechanical Design

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    The shaping of structural elements in the area of mechanical design is a recurrent problem. The mechanical designer, as a rule, chooses what is believed to be the “simplest” shapes, such as the geometric primitives: lines, circles and, occasionally, conics. The use of higher-order curves is usually not even considered, not to speak of other curves than polynomials. However, the simplest geometric shapes are not necessarily the most suitable when the designed element must withstand loads that can lead to failure-prone stress concentrations. Indeed, as mechanical designers have known for a while, stress concentrations occur, first and foremost, by virtue of either dramatic changes in curvature or extremely high values thereof. As an alternative, we propose here the use of smooth curves that can be simply generated using standard concepts such as non-parametric cubic splines. These curves can be readily used to produce either extruded surfaces or surfaces of revolution.

    Rotation symmetry axes and the quality index in a 3D octahedral parallel robot manipulator system

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    The geometry of a 3D octahedral parallel robot manipulator system is specified in terms of two rigid octahedral structures (the fixed and moving platforms) and six actuation legs. The symmetry of the system is exploited to determine the behaviour of (a new version of) the quality index for various motions. The main results are presented graphically

    Critical Thinking Activities and the Enhancement of Ethical Awareness: An application of a ‘Rhetoric of Disruption’ to the undergraduate general education classroom

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    This article explores how critical thinking activities and assignments can function to enhance students’ ethical awareness and sense of civic responsibility. Employing Levinas’s Othercentered theory of ethics, Burke’s notion of ‘the paradox of substance’, and Murray’s concept of ‘a rhetoric of disruption’, this article explores the nature of critical thinking activities designed to have students question their (often taken-for-granted) moral assumptions and interrogate their (often unexamined) moral identities. This article argues that such critical thinking activities can trigger a metacognitive destabilization of subjectivity, understood as a dialectical prerequisite (along with exposure to otherness) for increased ethical awareness. This theoretical model is illustrated through a discussion of three sample classroom activities designed to destabilize moral assumptions and identity, thereby clearing the way for a heightened acknowledgment of otherness. In so doing, this article provides an alternative (and dialectically inverted) strategy for addressing one of the central goals of many General Education curricula: the development of ethical awareness and civic responsibility. Rather than introducing students to alternative perspectives and divergent cultures with the expectation that heightened moral awareness will follow, this article suggests classroom activities and course assignments aimed at disrupting moral subjectivity and creating an opening in which otherness can be more fully acknowledged and the diversity of our world more fully appreciated

    Reconstruction of a Genetic Pathway Using Transcriptome Mapping in a Metazoan

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    RNA‐seq is a technique that is commonly used to identify downstream elements to a genetic or chemical perturbation. In theory, global transcriptomes contain enough information to perform a full‐fledged genetic analysis of a pathway. Early attempts to do this using microarrays in single celled organisms reported partial reconstruction of a genetic pathway. Using the hypoxia pathway, we show that genetic reconstructions can be performed using global transcriptome data. We obtained the transcriptomes of 5 C. elegans single mutants and 2 double mutants at the young adult stage. We show that in a blinded computational study, we were able to identify relevant genetic relationships between all genes in a pathway. In addition, we identified a core set of ~500 genes that make up the bulk of the C. elegans hypoxia response. Multiple of these genes are directly implicated in the Electron Transport Chain (ETC), metabolism regulation or chemical damage responses

    Voltage Stability Analysis of Grid-Connected Wind Farms with FACTS: Static and Dynamic Analysis

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    Recently, analysis of some major blackouts and failures of power system shows that voltage instability problem has been one of the main reasons of these disturbances and networks collapse. In this paper, a systematic approach to voltage stability analysis using various techniques for the IEEE 14-bus case study, is presented. Static analysis is used to analyze the voltage stability of the system under study, whilst the dynamic analysis is used to evaluate the performance of compensators. The static techniques used are Power Flow, V–P curve analysis, and Q–V modal analysis. In this study, Flexible Alternating Current Transmission system (FACTS) devices- namely, Static Synchronous Compensators (STATCOMs) and Static Var Compensators (SVCs) - are used as reactive power compensators, taking into account maintaining the violated voltage magnitudes of the weak buses within the acceptable limits defined in ANSI C84.1. Simulation results validate that both the STATCOMs and the SVCs can be effectively used to enhance the static voltage stability and increasing network loadability margin. Additionally, based on the dynamic analysis results, it has been shown that STATCOMs have superior performance, in dynamic voltage stability enhancement, compared to SVCs

    Short-term impacts of an unconditional cash transfer program on child schooling: Experimental evidence from Malawi.

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    This study analyzes the impact of a positive income shock on child schooling outcomes using experimental data from an unconditional cash transfer program in Malawi. Since households receive the cash and parents are responsible for making spending decisions, we also examine the intervening pathways between cash transfers and child schooling. Data comes from a cluster-randomized study of Malawi’s Social Cash Transfer Program (SCTP). After a baseline survey, households in village clusters were randomly assigned to treatment and control arms with treatment villages receiving transfers immediately and control villages assigned a later entry. We test for treatment impacts on a panel of school-aged children (6–17) using a differences-in-differences model. After a years’ worth of transfers, we find the Malawi SCTP both improves enrollment rates and decreases dropouts. The main intervening pathway between the program and schooling is education expenditures, suggesting that the cash improves the demand for education by reducing financial constraints

    Paying for Happiness: Experimental Results from a Large Cash Transfer Program in Malawi

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    This study analyzes the short-term impact of an exogenous, positive income shock on caregivers’ subjective well-being (SWB) in Malawi using panel data from 3,365 households targeted to receive Malawi’s Social Cash Transfer Program that provides unconditional cash to ultra-poor, labor-constrained households. The study consists of a cluster-randomized, longitudinal design. After the baseline survey, half of these village clusters were randomly selected to receive the transfer and a follow-up was conducted 17 months later. We find that the short-term impact of household income increases from the cash transfer leads to substantial SWB gains among caregivers. After a year’s worth of transfers, caregivers in beneficiary households have higher life satisfaction and are more likely to believe in a better future. We examine whether program impacts on consumption, food security, resilience, and hopefulness could explain the increase in SWB but do not find that any of these mechanisms individually mediate our results

    Measurement of Content of 226Ra in Drinking Water From Some States of Mexican Republic by Liquid Scintillation Method

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    To assess the quality of drinking water in respect to the content of radioactivity, usually is carried out an screening program in the locations of interest, that program consist in pick representative samples of drinking water from the wells in that locations, water samples are analyzed to measuring the gross alpha/beta radioactivity by a low background proportional counter or a liquid scintillation system. When some sample exceeds the normative limit then it must be known which radionuclides are in that sample. Expected radionuclides in water are the NORM (normal occurring radioactive material) from the natural radioactive chains. 226Ra is frequently present in drinking water and is one of most important radionuclide because its “radiotoxicity”, the WHO [World Health Organization, Guidelines for drinking-water Quality, (2016)] recommends a reference level for 226Ra of 1 Bq/L (the dose coefficient for 226Ra is 2.8 x 10-7 Sv/Bq). From a national program of drinking water screening in the Mexican Republic, the samples that exceeded the national normative limits were picked again in the same well and analyzed by LS (liquid Scintillation), using the method of two phases with a not water miscible scintillator cocktail. Results of concentrations of 226Ra from drinking water are presented. In general the content of 226Ra in drinking water samples was lower that the guide values recommended for the WHO
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