4,998 research outputs found

    Experiences with the Streptococcus mutans in Lakota Sioux (SMILeS) Study: Risk Factors for Caries in American Indian Children 0-3 Years

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    Severe Early Childhood Caries (S-ECC) is a terribly aggressive and devastating disease that is all too common in lower socio-economic children, but none more so that what is encountered in American Indian Tribes. Nationwide, approximately 27% of 2-5 year olds have decay while 62% percent of American Indian/Alaska Native children in the same age group have a history of decay (IHS 2010, NHANES 1999-2002). We have conducted a study of children from birth to 36 months of age on Pine Reservation to gain a better understanding of the variables that come into play in the development of this disease, from transmission and acquisition of Streptococcus mutans genotypes from mother to child to multiple dietary and behavioral components. This article describes how we established a direct partnership with the Tribe and the many opportunities and challenges we faced in performing this 5-year field study

    Transverse frames for Petrov type I spacetimes: a general algebraic procedure

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    We develop an algebraic procedure to rotate a general Newman-Penrose tetrad in a Petrov type I spacetime into a frame with Weyl scalars Ψ1\Psi_{1} and Ψ3\Psi_{3} equal to zero, assuming that initially all the Weyl scalars are non vanishing. The new frame highlights the physical properties of the spacetime. In particular, in a Petrov Type I spacetime, setting Ψ1\Psi_{1} and Ψ3\Psi_{3} to zero makes apparent the superposition of a Coulomb-type effect Ψ2\Psi_{2} with transverse degrees of freedom Ψ0\Psi_{0} and Ψ4\Psi_{4}.Comment: 10 pages, submitted to Classical Quantum Gravit

    Intrinsic Geometry of a Null Hypersurface

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    We apply Cartan's method of equivalence to construct invariants of a given null hypersurface in a Lorentzian space-time. This enables us to fully classify the internal geometry of such surfaces and hence solve the local equivalence problem for null hypersurface structures in 4-dimensional Lorentzian space-times

    Donor-side photoinhibition in photosystem II from Chlamydomonas reinhardtii upon mutation of tyrosine-Z in the D1 polypeptide to phenylalanine

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    AbstractWhen tyrosine-Z of the D1-polypeptide of the photosystem II from Chlamydomonas reinhardtii was changed to phenylalanine, the rapid donor to P680+ was lost, and P680+ accumulated on illumination. The rapid donation from tyrosine-Z was replaced by a slow electron transfer from an endogenous donor. Spectrophotometric measurements showed that carotenoids and chlorophylls were bleached by the P680+ either directly or indirectly upon illumination. The carotenoid bleaching was inhibited in the presence of SOD or catalase, but the reaction did not require molecular oxygen as an electron acceptor. These observations led us to conclude that active oxygen radicals, possibly hydroxyl radicals, take part in the destruction of carotenoids in the Y161F mutant. Possible mechanisms for the destruction are discussed

    Solution generating with perfect fluids

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    We apply a technique, due to Stephani, for generating solutions of the Einstein-perfect fluid equations. This technique is similar to the vacuum solution generating techniques of Ehlers, Harrison, Geroch and others. We start with a ``seed'' solution of the Einstein-perfect fluid equations with a Killing vector. The seed solution must either have (i) a spacelike Killing vector and equation of state P=rho or (ii) a timelike Killing vector and equation of state rho+3P=0. The new solution generated by this technique then has the same Killing vector and the same equation of state. We choose several simple seed solutions with these equations of state and where the Killing vector has no twist. The new solutions are twisting versions of the seed solutions

    Two body decays of the bb-quark: Applications to direct CP violation, searches for electro-weak penguins and new physics

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    A systematic experimental search for two-body hadronic decays of the b-quark of the type b to quark + meson is proposed. These reactions have a well defined experimental signature and they should be theoretically cleaner compared to exclusive decays. Many modes have appreciable branching ratios and partial rate asymmetries may also be quite large (about 8-50%) in several of them. In a few cases electroweak penguins appear to be dominant and may be measurable. CP violating triple correlation asymmetries provide a clean test of the Standard Model.Comment: 12 pages 1 figure 1 tabl

    Aerosol Insulin Induces Regulatory CD8 γδ T Cells That Prevent Murine Insulin-dependent Diabetes

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    Cellular immune hyporesponsiveness can be induced by the presentation of soluble protein antigens to mucosal surfaces. Most studies of mucosa-mediated tolerance have used the oral route of antigen delivery and few have examined autoantigens in natural models of autoimmune disease. Insulin is an autoantigen in humans and nonobese diabetic (NOD) mice with insulindependent diabetes mellitus (IDDM). When we administered insulin aerosol to NOD mice after the onset of subclinical disease, pancreatic islet pathology and diabetes incidence were both significantly reduced. Insulin-treated mice had increased circulating antibodies to insulin, absent splenocyte proliferation to the major epitope, insulin B chain amino acids 9–23, which was associated with increased IL-4 and particularly IL-10 secretion, and reduced proliferation to glutamic acid decarboxylase, another islet autoantigen. The ability of splenocytes from insulin-treated mice to suppress the adoptive transfer of diabetes to nondiabetic mice by T cells of diabetic mice was shown to be caused by small numbers of CD8 γδ T cells. These findings reveal a novel mechanism for suppressing cell-mediated autoimmune disease. Induction of regulatory CD8 γδ T cells by aerosol insulin is a therapeutic strategy with implications for the prevention of human IDDM

    Conceptions of Leadership: Enduring Ideas and Emerging Insights

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    Conceptions of Leadership gathers together the latest work by distinguished leadership scholars in social psychology and related disciplines to explore classic conceptions of leadership, such as interpersonal influence, charisma, personality, and power, as well as recent perspectives on those enduring concerns. It includes contemporary departures from traditional approaches to leadership in considering gender, trust, narratives, and the complex relationships between leaders and followers. Together the chapters provide a wide-ranging and coherent account of how human beings get along and the ways they engage and work together to accomplish their goals.https://scholarship.richmond.edu/bookshelf/1198/thumbnail.jp

    Profile instabilities of the millisecond pulsar PSR J1022+1001

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    We present evidence that the integrated profiles of some millisecond pulsars exhibit severe changes that are inconsistent with the moding phenomenon as known from slowly rotating pulsars. We study these profile instabilities in particular for PSR J1022+1001 and show that they occur smoothly, exhibiting longer time constants than those associated with moding. In addition, the profile changes of this pulsar seem to be associated with a relatively narrow-band variation of the pulse shape. Only parts of the integrated profile participate in this process which suggests that the origin of this phenomenon is intrinsic to the pulsar magnetosphere and unrelated to the interstellar medium. A polarization study rules out profile changes due to geometrical effects produced by any sort of precession. However, changes are observed in the circularly polarized radiation component. In total we identify four recycled pulsars which also exhibit instabilities in the total power or polarization profiles due to an unknown phenomenon (PSRs J1022+1001, J1730-2304, B1821-24, J2145-0750). The consequences for high precision pulsar timing are discussed in view of the standard assumption that the integrated profiles of millisecond pulsars are stable. As a result we present a new method to determine pulse times-of-arrival that involves an adjustment of relative component amplitudes of the template profile. Applying this method to PSR J1022+1001, we obtain an improved timing solution with a proper motion measurement of -17 \pm 2 mas/yr in ecliptic longitude. Assuming a distance to the pulsar as inferred from the dispersion measure this corresponds to an one-dimensional space velocity of 50 km/s.Comment: 29 pages, 12 figures, accepted for publication in Ap

    Successful lung transplantation for talcosis secondary to intravenous abuse of oral drug

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    Talcosis due to intravenous injection of oral drugs can cause severe pulmonary disease with progressive dyspnea even when drug use is discontinued. We describe a 54-year-old woman with severe emphysema who underwent left lung transplantation. The patient had a remote history of intravenous injection of crushed methylphenidate (Ritalin) tablets. Chest computed tomography showed severe emphysematous changes, more prominent in the lower lobes. Microscopic examination of the extracted lung demonstrated multinucleated giant cells with birefringent crystals, compatible with talcosis. At follow-up, daily symptoms were completely alleviated and lung function was good. We recommend that lung transplantation be considered as a viable option in the treatment of talcosis
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