101,761 research outputs found

    Trends in Concurrency, Polygyny, and Multiple Sex Partnerships During a Decade of Declining HIV Prevalence in Eastern Zimbabwe.

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    Background. Observed declines in the prevalence of human immunodeficiency virus (HIV) infection in Zimbabwe have been attributed to population-level reductions in sexual partnership numbers. However, it remains unknown whether certain types of sex partnerships were more important to this decline. Particular debate surrounds the epidemiologic importance of polygyny (the practice of having multiple wives). Methods. We analyze changes in reported multiple partnerships, nonmarital concurrency, and polygyny in eastern Zimbabwe during a period of declining HIV prevalence, from 1998 to 2011. Trends are reported for adult men (age, 17–54 years) and women (age, 15–49 years) from 5 survey rounds of the Manicaland HIV/STD Prevention Project, a general-population open cohort study. Results. At baseline, 34.2% of men reported multiple partnerships, 11.9% reported nonmarital concurrency, and 4.6% reported polygyny. Among women, 4.6% and 1.8% reported multiple partnerships and concurrency, respectively. All 3 partnership indicators declined by similar relative amounts (around 60%–70%) over the period. Polygyny accounted for around 25% of male concurrency. Compared with monogamously married men, polygynous men reported higher levels of subsequent divorce/separation (adjusted relative risk [RR], 2.92; 95% confidence interval [CI], 1.87–4.55) and casual sex partnerships (adjusted RR, 1.63; 95% CI, 1.41–1.88). Conclusions. No indicator clearly dominated declines in partnerships. Polygyny was surprisingly unstable and, in this population, should not be considered a safe form of concurrency

    Weak solutions to problems involving inviscid fluids

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    We consider an abstract functional-differential equation derived from the pressure-less Euler system with variable coefficients that includes several systems of partial differential equations arising in the fluid mechanics. Using the method of convex integration we show the existence of infinitely many weak solutions for prescribed initial data and kinetic energy

    Host Selection of the giant willow aphid (Tuberolachnus salignus)

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    The giant willow aphid [Tuberolachnus salignus (Gmelin)] has recently become noteworthy as a potential pest species due to the increased uptake of willow, its host-plant, for use in growing biomass for energy production. In this paper we describe host selection studies of T. salignus on short rotation coppice (SRC) willow varieties in laboratory bioassays and field experiments. In laboratory olfactometry tests, T. salignus was significantly attracted to certain SRC willow varieties, but not to others. Field trials during 2007 and 2008 showed that T. salignus infestation levels varied significantly on different SRC willow varieties and that levels are highest on the varieties to which they are most strongly attracted in the laboratory bioassays

    Center clusters in the Yang-Mills vacuum

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    Properties of local Polyakov loops for SU(2) and SU(3) lattice gauge theory at finite temperature are analyzed. We show that spatial clusters can be identified where the local Polyakov loops have values close to the same center element. For a suitable definition of these clusters the deconfinement transition can be characterized by the onset of percolation in one of the center sectors. The analysis is repeated for different resolution scales of the lattice and we argue that the center clusters have a continuum limit.Comment: Table added. Final version to appear in JHE

    Spontaneous time reversal symmetry breaking in the pseudogap state of high-Tc superconductors

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    When matter undergoes a phase transition from one state to another, usually a change in symmetry is observed, as some of the symmetries exhibited are said to be spontaneously broken. The superconducting phase transition in the underdoped high-Tc superconductors is rather unusual, in that it is not a mean-field transition as other superconducting transitions are. Instead, it is observed that a pseudo-gap in the electronic excitation spectrum appears at temperatures T* higher than Tc, while phase coherence, and superconductivity, are established at Tc (Refs. 1, 2). One would then wish to understand if T* is just a crossover, controlled by fluctuations in order which will set in at the lower Tc (Refs. 3, 4), or whether some symmetry is spontaneously broken at T* (Refs. 5-10). Here, using angle-resolved photoemission with circularly polarized light, we find that, in the pseudogap state, left-circularly polarized photons give a different photocurrent than right-circularly polarized photons, and therefore the state below T* is rather unusual, in that it breaks time reversal symmetry11. This observation of a phase transition at T* provides the answer to a major mystery of the phase diagram of the cuprates. The appearance of the anomalies below T* must be related to the order parameter that sets in at this characteristic temperature .Comment: 11 pages, 4 figure

    Endothelial Progenitors Exist within the Kidney and Lung Mesenchyme

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    The renal endothelium has been debated as arising from resident hemangioblast precursors that transdifferentiate from the nephrogenic mesenchyme (vasculogenesis) and/or from invading vessels (angiogenesis). While the Foxd1-positive renal cortical stroma has been shown to differentiate into cells that support the vasculature in the kidney (including vascular smooth muscle and pericytes) it has not been considered as a source of endothelial cell progenitors. In addition, it is unclear if Foxd1-positive mesenchymal cells in other organs such as the lung have the potential to form endothelium. This study examines the potential for Foxd1-positive cells of the kidney and lung to give rise to endothelial progenitors. We utilized immunofluorescence (IF) and fluorescence-activated cell sorting (FACS) to co-label Foxd1-expressing cells (including permanently lineage-tagged cells) with endothelial markers in embryonic and postnatal mice. We also cultured FACsorted Foxd1-positive cells, performed in vitro endothelial cell tubulogenesis assays and examined for endocytosis of acetylated low-density lipoprotein (Ac-LDL), a functional assay for endothelial cells. Immunofluorescence and FACS revealed that a subset of Foxd1-positive cells from kidney and lung co-expressed endothelial cell markers throughout embryogenesis. In vitro, cultured embryonic Foxd1-positive cells were able to differentiate into tubular networks that expressed endothelial cell markers and were able to endocytose Ac-LDL. IF and FACS in both the kidney and lung revealed that lineage-tagged Foxd1-positive cells gave rise to a significant portion of the endothelium in postnatal mice. In the kidney, the stromal-derived cells gave rise to a portion of the peritubular capillary endothelium, but not of the glomerular or large vessel endothelium. These findings reveal the heterogeneity of endothelial cell lineages; moreover, Foxd1-positive mesenchymal cells of the developing kidney and lung are a source of endothelial progenitors that are likely critical to patterning the vasculature. © 2013 Sims-Lucas et al

    Vacuum Stability of the wrong sign (−ϕ6)(-\phi^{6}) Scalar Field Theory

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    We apply the effective potential method to study the vacuum stability of the bounded from above (−ϕ6)(-\phi^{6}) (unstable) quantum field potential. The stability (∂E/∂b=0)\partial E/\partial b=0) and the mass renormalization (∂2E/∂b2=M2)\partial^{2} E/\partial b^{2}=M^{2}) conditions force the effective potential of this theory to be bounded from below (stable). Since bounded from below potentials are always associated with localized wave functions, the algorithm we use replaces the boundary condition applied to the wave functions in the complex contour method by two stability conditions on the effective potential obtained. To test the validity of our calculations, we show that our variational predictions can reproduce exactly the results in the literature for the PT\mathcal{PT}-symmetric ϕ4\phi^{4} theory. We then extend the applications of the algorithm to the unstudied stability problem of the bounded from above (−ϕ6)(-\phi^{6}) scalar field theory where classical analysis prohibits the existence of a stable spectrum. Concerning this, we calculated the effective potential up to first order in the couplings in dd space-time dimensions. We find that a Hermitian effective theory is instable while a non-Hermitian but PT\mathcal{PT}-symmetric effective theory characterized by a pure imaginary vacuum condensate is stable (bounded from below) which is against the classical predictions of the instability of the theory. We assert that the work presented here represents the first calculations that advocates the stability of the (−ϕ6)(-\phi^{6}) scalar potential.Comment: 21pages, 12 figures. In this version, we updated the text and added some figure

    Investigation of marmoset hybrids (Cebuella pygmaea x Callithrix jacchus) and related Callitrichinae (Platyrrhini) by cross-species chromosome painting and comparative genomic hybridization

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    We report on the cytogenetics of twin offspring from an interspecies cross in marmosets (Callitrichinae, Platyrrhini), resulting from a pairing between a female Common marmoset (Callithrix jacchus, 2n = 46) and a male Pygmy marmoset (Cebuella pygmaea, 2n = 44). We analyzed their karyotypes by multi-directional chromosome painting employing human, Saguinus oedipus and Lagothrix lagothricha chromosome-specific probes. Both hybrid individuals had a karyotype with a diploid chromosome number of 2n = 45. As a complementary tool, interspecies comparative genomic hybridization (iCGH) was performed in order to screen for genomic imbalances between the hybrids and their parental species, and between Callithrix argentata and S. oedipus, respectively. Copyright (C) 2005 S. Karger AG, Basel

    Effect Of The "spiritual Support" Intervention On Spirituality And The Clinical Parameters Of Women Who Have Undergone Mastectomy: A Pilot Study

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    This study aimed to evaluate the effect of the spiritual support intervention on spirituality and the clinical parameters of women who have undergone mastectomy. This is a pilot study of a randomized clinical trial. The spiritual support intervention was composed of meditation, guided imagery, music, and respiratory relaxation. The outcomes were: spirituality, blood pressure, heart rate, and oxygen saturation. A total of 27 patients were recruited for the study (intervention group, n = 13; control group, n = 14) (Clinical Trials: NCT 01866670/CAE: 00896312.0.0000.5393). The intervention helped patients with breast cancer to increase expression of their spirituality (p = 0.040) and it also decreased heart rate on the first (p = 0.038) and third day (p = 0.017). There was a difference in oxygen saturation on the second day in the control group (p = 0.039). Patients reported that their participation in the research was positive. This intervention had an effect on the sample of women who had undergone mastectomy.

    The computerized medical record as a tool for clinical governance in australian primary care

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    Background: Computerized medical records (CMR) are used in most Australian general practices. Although CMRs have the capacity to amalgamate and provide data to the clinician about their standard of care, there is little research on the way in which they may be used to support clinical governance: the process of ensuring quality and accountability that incorporates the obligation that patients are treated according to best evidence. Objective: The objective of this study was to explore the capability, capacity, and acceptability of CMRs to support clinical governance. Methods: We conducted a realist review of the role of seven CMR systems in implementing clinical governance, developing a four-level maturity model for the CMR. We took Australian primary care as the context, CMR to be the mechanism, and looked at outcomes for individual patients, localities, and for the population in terms of known evidence-based surrogates or true outcome measures. Results: The lack of standardization of CMRs makes national and international benchmarking challenging. The use of the CMR was largely at level two of our maturity model, indicating a relatively simple system in which most of the process takes place outside of the CMR, and which has little capacity to support benchmarking, practice comparisons, and population-level activities. Although national standards for coding and projects for record access are proposed, they are not operationalized. Conclusions: The current CMR systems can support clinical governance activities; however, unless the standardization and data quality issues are addressed, it will not be possible for current systems to work at higher levels
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