1,892 research outputs found

    Fluorine in animal nutrition

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    Enhancement of Disease and Pathology by Synergy of Trichuris Suis and Campylobacter Jejuni in the Colon of Immunologically Naive Swine

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    Campylobacter jejuni, a leading cause of bacterial gastroenteritis, has different age distribution and disease expression in developing and developed countries, which may be due to the endemnicity of infection and the age of acquisition of immunity. Differences in disease expression are not solely dependent on the C jejuni strain or virulence attributes. Another modulating factor in developing countries may be endemic nematode infections such as Trichuris, which drive type 2 cytokine responses and down-regulate type I immune responses. In this study, three-day-old germfree pigs given dual infections with Trichuris suis and C jejuni had more frequent, more severe diarrhea and severe pathology than pigs given no pathogens, only T. suis, or only C jejuni. These pigs had significant hemorrhage and inflammatory cell infiltrates in the proximal colon where adult worms were found, and abscessed lymphoglandular complexes in the distal colon with intracellular C jejuni. Pigs given only C jejuni had mild clinical signs and pathology, and bacteria in feces or extracellular sites. Pigs given T suis or no pathogens had no disease and minimal pathology. Thus, these agents synergized to produce significant disease and pathology, which was site specific

    Anesthesia and cognitive performance in children: No evidence for a causal relationship

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    * Both authors contributed evenly to the manuscript Recent findings of an association between anesthesia administration in the first three years of life and later learning disabilities have created concerns that anesthesia has neurotoxic effects on synaptogenesis, causing later learning problems. An alternative hypothesis is that those children who are likely to undergo surgery early in life have significant medical problems that are associated with a vulnerability to learning disabilities. These two hypotheses were evaluated in a monozygotic concordant–discordant twin design. Data on anesthesia administration and learning abilities and disabilities were available for 1,143 monozygotic twin pairs (56 % female) from the Netherlands Twin Registry. Parents of the twins reported on anesthesia use before age 3 and again between ages 3 and 12 years. Near age 12, educational achievement and cognitive problems were assessed with standardized tests and teacher ratings. Results showed that twins who were exposed to anesthesia before age 3 had significantly lower educational achievement scores and significantly more cognitive problems than twins not exposed to anesthesia. However, there was one important exception: the unexposed co-twin from discordant pairs did not differ from their exposed cotwin. Thus, there is no evidence for a causal relationship between anesthesia administration and later learning-related outcomes in this sample. Rather, there is evidence for early anesthesia being a marker of an individual’s vulnerability for later learning problems, regardless of their exposure to anesthesia

    Transforming Post-Secondary Education in Mathematics

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    In this manuscript, I introduce and describe the work of mathematicians and mathematics educators in the group Transforming Post-Secondary Education in Mathematics (TPSE Math or TPSE, pronounced "tipsy", for short). TPSE aims to coordinate and drive constructive change in education in the mathematical sciences at two-year colleges, four-year colleges, and universities across the nation. It seeks to build on the successes of the entire mathematical sciences community. This manuscript reviews the events that led to the founding of TPSE Math and articulates its vision and mission. In its first phase with national events, TPSE found broad consensus with the mathematical sciences community on the challenges facing the community. Learning from educational transformations experiences in other scientific fields, and with the support of the Mathematical Advisory Group of 34 mathematical sciences department chairs and leaders, TPSE moves into a second phase focused on action. This is a snapshot in time, and TPSE's ongoing activities will continue to be documented and disseminated. The piece concludes with a reflection of the impact that my involvement in this work has had on my career.Comment: 17 page

    Conformal Ablative Thermal Protection Systems (CA-TPS) for Venus and Saturn Backshells

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    The new conformal ablator C-PICA, which was developed under STMD GCD, is an optimal candidate for use on the backshells for high velocity entry vehicles at both Venus and Saturn. The material has been tested at heat fluxes up to 400 Wcm2 in shear and over 1800 Wcm2 and 1.5 atm in stagnation with good results. C-PICA has similar density to PICA, but shows half the thermal penetration and similar recession at the same conditions, allowing for a lighter weight TPS to be flown. This poster for VEXAG will show the progress made in the development of the material and why it should be considered for use

    Conformal Ablative Thermal Protection Systems (CA-TPS) for Venus and Saturn Backshells

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    This poster provides an overview of the work performed to date on the Conformal Ablative TPS (CA-TPS) element of the TPSM project out of GCDP. Under this element, NASA is developing improved ablative TPS materials based on flexible felt for reinforcement rather than rigid reinforcements. By replacing the reinforcements with felt, the resulting materials have much higher strain-to-failure and are much lower in thermal conductivity than their rigid counterparts. These characteristics should allow for larger tile sizes, direct bonding to aeroshells and even lower weight TPS. The conformal phenolic impregnated carbon felt (C-PICA) is a candidate for backshell TPS for both Venus and Saturn entry vehicles
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