828 research outputs found

    Commentary: Entropy and Skewness in the Allocation of Students to Law Schools

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    I wish to comment on the obligation assumed by law schools, as the primary port of entry into the legal profession, one, to recruit selectively the intellectually best qualified aspirants to law and two, to base admission decisions upon scholastic ability and performance (or compensatory affirmative action) rather than on the basis of ascriptive status characteristics. As I will show, the former process is evincing strong signs of entropy; the latter, of continued skewness

    A prototypical model for tensional wrinkling in thin sheets

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    The buckling and wrinkling of thin films has recently seen a surge of interest among physicists, biologists, mathematicians and engineers. This has been triggered by the growing interest in developing technologies at ever decreasing scales and the resulting necessity to control the mechanics of tiny structures, as well as by the realization that morphogenetic processes, such as the tissue-shaping instabilities occurring in animal epithelia or plant leaves, often emerge from mechanical instabilities of cell sheets. While the most basic buckling instability of uniaxially compressed plates was understood by Euler more than 200 years ago, recent experiments on nanometrically thin (ultrathin) films have shown significant deviations from predictions of standard buckling theory. Motivated by this puzzle, we introduce here a theoretical model that allows for a systematic analysis of wrinkling in sheets far from their instability threshold. We focus on the simplest extension of Euler buckling that exhibits wrinkles of finite length - a sheet under axisymmetric tensile loads. This geometry, whose first study is attributed to Lam´e, allows us to construct\ud a phase diagram that demonstrates the dramatic variation of wrinkling patterns from near-threshold to far-from-threshold conditions. Theoretical arguments and comparison to experiments show that for thin sheets the far-from-threshold regime is expected to emerge under extremely small compressive loads, emphasizing the relevance of our analysis for nanomechanics applications

    Runx3 and T-box proteins cooperate to establish the transcriptional program of effector CTLs

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    Activation of naive CD8+ T cells with antigen induces their differentiation into effector cytolytic T lymphocytes (CTLs). CTLs lyse infected or aberrant target cells by exocytosis of lytic granules containing the pore-forming protein perforin and a family of proteases termed granzymes. We show that effector CTL differentiation occurs in two sequential phases in vitro, characterized by early induction of T-bet and late induction of Eomesodermin (Eomes), T-box transcription factors that regulate the early and late phases of interferon (IFN) γ expression, respectively. In addition, we demonstrate a critical role for the transcription factor Runx3 in CTL differentiation. Runx3 regulates Eomes expression as well as expression of three cardinal markers of the effector CTL program: IFN-γ, perforin, and granzyme B. Our data point to the existence of an elaborate transcriptional network in which Runx3 initially induces and then cooperates with T-box transcription factors to regulate gene transcription in differentiating CTLs

    Variational Two Fermion Wave Equations in QED: Muonium Like Systems

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    We consider a reformulation of QED in which covariant Green functions are used to solve for the electromagnetic field in terms of the fermion fields. The resulting modified Hamiltonian contains the photon propagator directly. A simple Fock-state variational trial function is used to derive relativistic two-fermion equations variationally from the expectation value of the Hamiltonian of the field theory. The interaction kernel of the equation is shown to be, in essence, the invariant M-matrix in lowest order. Solutions of the two-body equations are presented for muonium like system for small coupling strengths. The results compare well with the observed muonium spectrum, as well as that for hydrogen and muonic hydrogen. Anomalous magnetic moment effects are discussed

    Reduced selenium concentrations and glutathione peroxidase activity in preeclamptic pregnancies

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    Preeclampsia is a pregnancy-specific condition affecting 2-7% of women and a leading cause of perinatal and maternal morbidity and mortality. Preeclampsia may also predispose the fetus to increased risks of adult cardiovascular disease. Selenium, acting through the selenoprotein glutathione peroxidases, has critical roles in regulating antioxidant status. Recent reports implicate poor maternal selenium status as a nutritional factor predisposing the mother to preeclampsia but the fetus and placenta have not been studied in tandem. Measurement of selenium concentrations, expression and activity levels of glutathione peroxidase and markers of oxidative stress were performed on maternal and umbilical venous blood samples or the placenta from 27 normal pregnant, 25 preeclamptic and 22 healthy age-matched non-pregnant women. The results of this study revealed highly significant reductions in serum selenium concentrations and plasma glutathione peroxidase activity in pregnancy per se compared to non-pregnant controls. Moreover, these levels were further decreased in the preeclamptic mothers and babies compared to normal pregnancies. Umbilical venous selenium was particularly low (42.1±11.8 and 29.0 ± 9.9 mug/L; mean ±s.d.; P<0.05). Both mother and baby had significantly increased levels of markers for oxidative stress in the preeclamptic group. The placental glutathione peroxidase activity and immunohistochemical staining were also reduced in the preeclampsia placentae. Oxidative stress associated with preeclampsia may be a consequence of reduced antioxidant defence pathways specifically involving glutathione peroxidases, perhaps linked to reduced selenium availability. Reduced glutathione peroxidases could be associated with increased generation of toxic lipid peroxides contributing to the endothelial dysfunction and hypertension of preeclampsia

    EPR correlations and EPW distributions revisited

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    It is shown that Bell's proof of violation of local realism in phase space is incorrect. Using Bell's approach, a violation can be derived also for nonnegative Wigner distributions. The error is found to lie in the use of an unnormalizable Wigner function.Comment: 7 pages, 1 figure, accepted to Phys. Lett.

    Expression of voltage-dependent potassium channels in first trimester human placentae

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    Potassium channel α-subunits encoded by KCNQ1-5 genes form voltage-dependent channels (Kv7), modulated by KCNE1-5 encoded accessory proteins. The aim was to determine KCNQ and KCNE mRNA expression and assess protein expression/localisation of the KCNQ3 and KCNE5 isoforms in first trimester placental tissue. Placentae were obtained from women undergoing elective surgical termination of pregnancy (TOP) at 10 weeks’ (mid TOP) gestations. KCNQ1-5 expression was unchanged during the first trimester. KCNE5 expression increased in mid TOP vs. early TOP samples (P=0.022). This novel study reports mRNA and protein expression of Kv7 channels in first trimester placentae

    Novel expression and regulation of voltage-dependent potassium (KV7) channels in placentae from women with preeclampsia

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    Preeclampsia is associated with structural/functional alterations in placental and maternal vasculature. KV7 (voltage-dependant potassium channels encoded by KCNQ1-5 genes) have been detected in several types of blood vessels where they promote vascular relaxation. KV7 channel function can be modulated by KCNE1-5 encoded accessory proteins. The aim of this study was to determine whether KCNQ and KCNE genes are differentially expressed in placentae from women with preeclampsia compared to normotensive controls and to examine any differences in those who delivered preterm (<37 weeks’) or term. Placental biopsies (from midway between the cord and periphery) were obtained, with consent, from White European control (n=24, term) and preeclamptic (n=22; of whom 8 delivered before 37 weeks’) women. KCNQ/KCNE and GAPDH mRNA expression was determined by qRT-PCR. Protein expression/localisation was assessed using immunohistochemistry. KCNQ3 and KCNE5 mRNA expression was significantly up-regulated in preeclampsia (median [IQR]: 1.942 [0.905, 3.379]) versus controls (0.159 [0.088, 0.288]; p=0.001) and exhibited a strong positive correlation with each other (p<0.001) suggesting a novel heterodimer. Enhanced protein expression of KCNQ3 and KCNE5 in preeclampsia was confirmed with localisation mainly restricted to the syncytiotrophoblast. KCNQ4 and KCNE1 isoforms were suppressed in placenta from term preeclamptic women versus controls (p≤0.05). KCNQ1 mRNA expression was increased and KCNQ5 decreased in the preterm preeclamptic group versus controls (p<0.05). In summary, KV7 channels are expressed and markedly modulated in placenta from preeclamptic women. Differential expression of isoforms may lead to altered cell proliferation. The correlation between KCNQ3 and KCNE5 expression is indicative of a novel channel complex and warrants further investigation

    Washington State&apos;s adoption of a child welfare practice model: An illustration of the Getting To Outcomes implementation framework

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    a b s t r a c t a r t i c l e i n f o Despite a great need for evidence-informed practices in child welfare, very few child welfare systems have implemented evidence-based case management models state-wide. While the literature on implementation from the perspective of model developers and researchers is steadily increasing, there has been little attention to the process of implementation originating from the reverse direction, by community organizations themselves, or with regard to going-to-scale implementation in child welfare. The Getting to Outcomes (GTO) model, which was originally created to help organizations choose and implement prevention programs, is a promising guide for child welfare systems seeking to initiate system-wide implementation of evidence-based practices. The GTO framework provides a step-by-step guide for surveying a system, building motivation, training, and evaluation. This article will illustrate the state-wide implementation of Solution-Based Casework (SBC), an evidence-based model of case management, by Washington State&apos;s Children&apos;s Administration, following the GTO framework. Despite some barriers and obstacles, the GTO model proved to be feasible and to aide in the implementation of SBC. Implications for the GTO model as a framework for empowering community organizations to choose and implement relevant evidence-based practices will be discussed
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