1,126 research outputs found

    An Analysis of Pre-Service Versus Experienced Special-Education Teachers’ Perceptions of Attrition

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    In this quantitative study, I assessed the presence of factors related to attrition in pre-service special educators. I surveyed 23 pre-service special educators regarding various attrition factors identified in the research literature and then compared their responses to the perceptions of 32 seasoned special educators to test for statistical significance. Participants were located at a large, public university in the southeast United States and the largest public-school system in proximity to the university. The results of the study indicated that attrition factors may be evidenced in pre-service educators and therefore detectable prior to entering the teaching field. The study also found that pre-service educators frequently had low expectations for what they would face. For instance, compared to the reality reported by the experienced educators, the pre-service educators expected to do more work and have fewer resources available to them. However, they also expected there to be more collaboration and support, and they expected areas such as paperwork to be more meaningful than the experienced educators reported was the case. The results help to direct future research by noting areas in which the expectations of the pre-service educators differed from those of the experienced educators, such as the expectation of building relationships

    Thermodynamic Analyses of Fuel Production Via Solar-Driven Ceria-Based Nonstoichiometric Redox Cycling: A Case Study of the Isothermal Membrane Reactor System

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    A thermodynamic model of an isothermal ceria-based membrane reactor system is developed for fuel production via solar-driven simultaneous reduction and oxidation reactions. Inert sweep gas is applied on the reduction side of the membrane. The model is based on conservation of mass, species, and energy along with the Gibbs criterion. The maximum thermodynamic solar-to-fuel efficiencies are determined by simultaneous multivariable optimization of operational parameters. The effects of gas heat recovery and reactor flow configurations are investigated. The results show that maximum efficiencies of 1.3% (3.2%) and 0.73% (2.0%) are attainable for water splitting (carbon dioxide splitting) under counter- and parallel-flow configurations, respectively, at an operating temperature of 1900 K and 95% gas heat recovery effectiveness. In addition, insights on potential efficiency improvement for the membrane reactor system are further suggested. The efficiencies reported are found to be much lower than those reported in literature. We demonstrate that the thermodynamic models reported elsewhere can violate the Gibbs criterion and, as a result, lead to unrealistically high efficiencies. The present work offers enhanced understanding of the counter-flow membrane reactor and provides more accurate upper efficiency limits for membrane reactor systems. © 2019 by ASME.Australian Research Council (Wojciech Lipiński, Future Fellowship, Award No. FT140101213, Funder ID. 10.13039/501100000923). China Scholarship Council (Sha Li, Grant No. [2015] 3022, 201506020092, Funder ID. 10.13039/501100004543)

    Sports Nutrition: What the Future may Bring

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    The field of sports nutrition is a dynamic one. Core competencies in exercise physiology, psychology, integrated metabolism and biochemistry are the initial parameters for a successful career in sports nutrition. In addition to the academic fundamentals, it is imperative that the sports nutritionist understand the sport in which our client participates. This sport specific understanding should manifest itself in fuel utilization, mechanics of movement, as well as psychological processes that motivate the participant to perform optimally. Sports nutrition as a field has grown substantially over the past 50 years, from glycogen loading to today's scientifically validated ergogenic aids. The last ten years has seen the largest advancement of sports nutrition, with the following areas driving much of the research: the effects of exercise on protein utilization, meal timing to maximize the anabolic response, the potential for ribose to benefit those engaged in high-energy repetitive sports, and creatine and its uses within athletics and medicine. The future of sports nutrition will dictate that we 1) collectively strive for a higher standard of care and education for counseling athletes and 2) integrate different disciplines. We are in an era of unprecedented growth and the new knowledge is constantly evolving. The International Society of Sports Nutrition (ISSN) will contribute to this exciting field in many ways, and we ask for your contribution by sharing your passion, stories, research, and life experiences with us

    Podofilox-Induced Regression of Shope Papillomas May Be Independent of Host Immunity

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    We tested the hypothesis that infiltrating leukocytes might contribute to papilloma destruction following podofilox treatment. New Zealand White (NZW) rabbits were inoculated with cottontail rabbit papillomavirus (CRPV) onto abraded areas of the dorsal skin. At 21 d after viral inoculation, 5.0% podofilox solution was applied to some papillomas, whereas others were used as controls. Three rabbits were sacrificed at each of three different periods after treatment initiation (1, 4, and 7 d). Four monoclonal antibodies (MoAbs), RG-16 (for B cells), L11/135 (specific for T cells), 2C4 (specific for class II antigen), and Ki67 (specific for proliferating cells), were used in an immunohistochemical study. All positive cells and total cells in the field were counted with an ocular grid. After 1 d of treatment, proliferation of papilloma cells was strongly suppressed in treated papillomas, but leukocytic infiltration was not altered. At 4 d and 7 d of treatment, there were substantial increases (about two to three times) in the numbers of B and T cells and class II – expressing leukocytes. The upper layers of the papillomas were highly necrotic and cell proliferation was absent in an layers. These data support the view that podofilox has a direct toxic effect on papilloma tissue. Leukocyte infiltration is not strongly associated with papilloma tissue and may not contribute to papilloma destruction

    The effects of age on skeletal muscle and the phosphocreatine energy system: can creatine supplementation help older adults

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    Creatine supplementation has been found to significantly increase muscle strength and hypertrophy in young adults (≤ 35 yr) particularly when consumed in conjunction with a resistance training regime. Literature examining the efficacy of creatine supplementation in older adults (55-82 yr) suggests creatine to promote muscle strength and hypertrophy to a greater extent than resistance training alone. The following is a review of literature reporting on the effects of creatine supplementation on intramuscular high energy phosphates, skeletal muscle morphology and quality of life in older adults. Results suggest creatine supplementation to be a safe, inexpensive and effective nutritional intervention, particularly when consumed in conjunction with a resistance training regime, for slowing the rate of muscle wasting that is associated with aging. Physicians should strongly consider advising older adults to supplement with creatine and to begin a resistance training regime in an effort to enhance skeletal muscle strength and hypertrophy, resulting in enhanced quality of life

    Analysis of the efficacy, safety, and regulatory status of novel forms of creatine

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    Creatine has become one of the most popular dietary supplements in the sports nutrition market. The form of creatine that has been most extensively studied and commonly used in dietary supplements is creatine monohydrate (CM). Studies have consistently indicated that CM supplementation increases muscle creatine and phosphocreatine concentrations by approximately 15–40%, enhances anaerobic exercise capacity, and increases training volume leading to greater gains in strength, power, and muscle mass. A number of potential therapeutic benefits have also been suggested in various clinical populations. Studies have indicated that CM is not degraded during normal digestion and that nearly 99% of orally ingested CM is either taken up by muscle or excreted in urine. Further, no medically significant side effects have been reported in literature. Nevertheless, supplement manufacturers have continually introduced newer forms of creatine into the marketplace. These newer forms have been purported to have better physical and chemical properties, bioavailability, efficacy, and/or safety profiles than CM. However, there is little to no evidence that any of the newer forms of creatine are more effective and/or safer than CM whether ingested alone and/or in combination with other nutrients. In addition, whereas the safety, efficacy, and regulatory status of CM is clearly defined in almost all global markets; the safety, efficacy, and regulatory status of other forms of creatine present in today’s marketplace as a dietary or food supplement is less clear

    Image-Guided Raman Spectroscopic Recovery of Canine Cortical Bone Contrast in Situ

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    Raman scattering provides valuable biochemical and molecular markers for studying bone tissue composition with use in predicting fracture risk in osteoporosis. Raman tomography can image through a few centimeters of tissue but is limited by low spatial resolution. X-ray computed tomography (CT) imaging can provide high-resolution image-guidance of the Raman spectroscopic characterization, which enhances the quantitative recovery of the Raman signals, and this technique provides additional information to standard imaging methods. This hypothesis was tested in data measured from Teflon tissue phantoms and from a canine limb. Image-guided Raman spectroscopy (IG-RS) of the canine limb using CT images of the tissue to guide the recovery recovered a contrast of 145:1 between the cortical bone and background. Considerably less contrast was found without the CT image to guide recovery. This study presents the first known IG-RS results from tissue and indicates that intrinsically high contrasts (on the order of a hundred fold) are available

    MODELING THE ROOT-KNOT NEMATODE/NUTSEDGE PEST COMPLEX: PERSPECTIVES FROM WEED SCIENCE, NEMATOLOGY AND STATISTICS

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    Previous research by the authors has established that southern root-knot nematode (SRKN, Meloidogyne incognita (Kofoid & White) Chitwood) and yellow and purple nutsedge (YNS, Cyperus esculentus L. and PNS, C. rotundus L.) form a pest-complex that adversely affects a wide variety of crops in the southern and western U.S. These pests appear to have co-evolved a mutually-beneficial relationship that promotes the survival of both nematodes and weeds to the detriment of crops. Traditional management has usually targeted one pest at a time, but managing this pest complex requires that all members of the complex be managed simultaneously. A series of experiments was performed to determine if this specific pest complex could be managed through crop-rotation using a non-dormant M. incognita-resistant variety of alfalfa (Medicago sativa) which can aggressively compete with, and hence decrease, occurrence of both species of nutsedges (NS), and subsequently decrease SRKN by decreasing the availability of root systems of host plants. A previous journal article discussed predicting counts of SRKN second-stage juveniles (SRKN-J2) as a function of YNS and PNS plant counts from a two-year alfalfa rotation experiment, using the Poisson distribution and a scale parameter to handle problems of overdispersion. In this paper, we examine three generalizations of the Poisson distribution that allow for the count variance being larger than the mean count: the Generalized Poisson, the Zero-Inflated Poisson (ZIP), and the Poisson Hurdle. The ZIP and Hurdle Poisson distributions both account for zero counts as a separate part of the distribution, while the Generalized Poisson incorporates a separate parameter that increases the variance relative to the mean. Different biological scenarios are presented for which each of these three general Poisson distributions might be logically appropriate. In addition, we use the alfalfa rotation data to present comparisons of fitted regression models of the three general Poisson distributions to the results from the previous analysis using the Poisson. For this data, there was no single probability distribution that worked best for all six sampling dates (three in each of the two years). This is not surprising in that over time the alfalfa rotation was, as planned, decreasing both nutsedge and nematode counts, thus presenting a moving target for the modeling process
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