972 research outputs found

    Variational Trajectory Optimization Tool Set: Technical description and user's manual

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    The algorithms that comprise the Variational Trajectory Optimization Tool Set (VTOTS) package are briefly described. The VTOTS is a software package for solving nonlinear constrained optimal control problems from a wide range of engineering and scientific disciplines. The VTOTS package was specifically designed to minimize the amount of user programming; in fact, for problems that may be expressed in terms of analytical functions, the user needs only to define the problem in terms of symbolic variables. This version of the VTOTS does not support tabular data; thus, problems must be expressed in terms of analytical functions. The VTOTS package consists of two methods for solving nonlinear optimal control problems: a time-domain finite-element algorithm and a multiple shooting algorithm. These two algorithms, under the VTOTS package, may be run independently or jointly. The finite-element algorithm generates approximate solutions, whereas the shooting algorithm provides a more accurate solution to the optimization problem. A user's manual, some examples with results, and a brief description of the individual subroutines are included

    Adolescents care but don't feel responsible for farm animal welfare

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    Adolescents are the next generation of consumers with the potential to raise standards of farm animal welfare—to theirsatisfaction—if their preferences and concerns are translated into accurate market drivers and signals. There are no published data about adolescent views of farm animal welfare to allow meaningful design, implementation, and evaluation of educational strategies to improve consideration of—and behavior toward—farm animals. Knowledge of farm animal welfare, as well as beliefs and attitudes about farm animal welfare and behavioral intention relevant to it were determined in a sample of ukadolescents, using a survey incorporating an extended version of the theory of planned behavior and novel assessment tools. Our results indicate that adolescents have only a limited knowledge of welfare problems for farm animals and welfare-relevant product labels. Intentions to identify welfare standards for the animals from whom their food was derived were weak. Although they cared about farm animal welfare and agreed with fundamental principles—for example, the provision of space and the absence of pain and suffering—like adults they held limited belief in the power and responsibility that they possess through their choices as consumers; responsibility was often shifted to others, such as the government and farmers

    E-Cigarette Availability, Price Promotions and Marketing at the Point-of Sale in the Contiguous United States (2014-2015): National Estimates and Multilevel Correlates

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    Electronic cigarette (e-cigarette) sales and use have increased rapidly, yet point-of-sale e-cigarette availability and marketing is understudied. We estimated changes in e-cigarette availability and marketing among tobacco retailers in the U.S., and associations with neighborhood characteristics. A national sample of tobacco retailers in the Contiguous U.S. was audited in 2014 and 2015 (n = 1,905 and n = 2,126, respectively) to observe e-cigarette availability and marketing (signs, ads, displays and promotions) and generate national prevalence estimates. Store, neighborhood and state level correlates of 2015 e-cigarette availability, price promotions and exterior advertising were analyzed using multilevel mixed-effects generalized linear models. E-cigarettes were sold at 72.0% of retailers in 2014 and at 79.2% in 2015. Price promotions increased from 11.9% to 20.2% of retailers. Among retailers that did not previously sell e-cigarettes in 2012, availability in 2015 was greater for retailers in neighborhoods with the highest proportion of Black residents (vs. lowest). E-cigarette price promotions were more prevalent in neighborhoods with more Hispanic residents, while exterior e-cigarette marketing was more prevalent in neighborhoods with more Black residents. State smoking prevalence was positively associated with e-cigarette availability, promotions and advertising. E-cigarette point-of-sale availability and marketing increased between 2014 and 2015 and expanded to neighborhoods with a higher proportion of Black residents between 2012 and 2015. Retailers located within states with high smoking prevalence appear to be targeted by e-cigarette marketing. As e-cigarettes become the target of more regulations, understanding changes in the e-cigarette retail environment is critical to inform potential policies regulating their sale and marketing

    Energy recovery in individuals with knee osteoarthritis.

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    OBJECTIVE: Pathological gaits have been shown to limit transfer between potential (PE) and kinetic (KE) energy during walking, which can increase locomotor costs. The purpose of this study was to examine whether energy exchange would be limited in people with knee osteoarthritis (OA). METHODS: Ground reaction forces during walking were collected from 93 subjects with symptomatic knee OA (self-selected and fast speeds) and 13 healthy controls (self-selected speed) and used to calculate their center of mass (COM) movements, PE and KE relationships, and energy recovery during a stride. Correlations and linear regressions examined the impact of energy fluctuation phase and amplitude, walking velocity, body mass, self-reported pain, and radiographic severity on recovery. Paired t-tests were run to compare energy recovery between cohorts. RESULTS: Symptomatic knee OA subjects displayed lower energetic recovery during self-selected walking speeds than healthy controls (P = 0.0018). PE and KE phase relationships explained the majority (66%) of variance in recovery. Recovery had a complex relationship with velocity and its change across speeds was significantly influenced by the self-selected walking speed of each subject. Neither radiographic OA scores nor subject self-reported measures demonstrated any relationship with energy recovery. CONCLUSIONS: Knee OA reduces effective exchange of PE and KE, potentially increasing the muscular work required to control movements of the COM. Gait retraining may return subjects to more normal patterns of energy exchange and allow them to reduce fatigue

    Timing of HIV Seroreversion Among HIV-Exposed, Breastfed Infants in Malawi: Type of HIV Rapid Test Matters

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    Introduction Rapid HIV serological tests are a cost-effective, point-of-care test among HIV exposed infants but cannot distinguish between maternal and infant antibodies. The lack of data on the timing of decay of maternal antibodies in young infants hinders the potential use of rapid tests in exposed infants. We aimed to determine the time to seroreversion for two commonly used rapid tests in a prospective cohort of HIV-exposed breastfeeding infants ages 3-18 months of life. Methods We collected data on the performance of two commonly used rapid tests (Determine and Unigold) in Malawi between 2008 and 2012 or at the University of North Carolina between 2014 and 2015. Time to seroreversion was estimated for both rapid tests using the Kaplan-Meier product limit estimator which allows for interval censored data. Results At 3 months of age, 3 % of infants had seroreverted according to Determine and 7 % had seroreverted according to Unigold. About one in four infants had achieved seroreversion by 4 months using Unigold, but only about one in twelve infants by 4 months when using Determine. More than 95 % of all infants had seroverted by 7 months according to Unigold and by 12 months according to the Determine assay. Discussion We show that the time of seroreversion depends greatly on the type of test used. Our results highlight the need for recommendations to specify the timing and type of test used in the context of infant HIV detection in resource-poor settings, and base the interpretation of test result on knowledge of time to seroreversion of the selected test

    Social Work Student Interests in Rural Practice

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    This study of BSW and MSW students (N = 122) in the School of Social Work at New Mexico State University reports student attitudes, concerns and interest in rural social work practice and rural social work practice curriculum. Strong support for rural social work practice and concomitant rural curriculum was evidenced by 93% who believed that social workers should practice in rural areas and 22% who ideally want to practice only in a rural community. Originally conceptualized and conducted to gather background data in support of a rural social work practice curriculum minor, its broader implications for rural social work practice curriculum are reported and discussed. Special attention is paid to implications for social work educational programs in rural states
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