4,022 research outputs found

    A Candidate Subspecies Discrimination System Involving a Vomeronasal Receptor Gene with Different Alleles Fixed in \u3ci\u3eM. m. domesticus\u3c/i\u3e and \u3ci\u3eM. m. musculus\u3c/i\u3e

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    Assortative mating, a potentially efficient prezygotic reproductive barrier, may prevent loss of genetic potential by avoiding the production of unfit hybrids (i.e., because of hybrid infertility or hybrid breakdown) that occur at regions of secondary contact between incipient species. In the case of the mouse hybrid zone, where two subspecies of Mus musculus (M. m. domesticus and M. m. musculus) meet and exchange genes to a limited extent, assortative mating requires a means of subspecies recognition. We based the work reported here on the hypothesis that, if there is a pheromone sufficiently diverged between M. m. domesticus and M. m. musculus to mediate subspecies recognition, then that process must also require a specific receptor(s), also sufficiently diverged between the subspecies, to receive the signal and elicit an assortative mating response. We studied the mouse V1R genes, which encode a large family of receptors in the vomeronasal organ (VNO), by screening Perlegen SNP data and identified one, Vmn1r67, with 24 fixed SNP differences most of which (15/24) are nonsynonymous nucleotide substitutions between M. m. domesticus and M. m. musculus. We observed substantial linkage disequilibrium (LD) between Vmn1r67 and Abpa27, a mouse salivary androgen-binding protein gene that encodes a proteinaceous pheromone (ABP) capable of mediating assortative mating, perhaps in conjunction with its bound small lipophilic ligand. The LD we observed is likely a case of association rather than residual physical linkage from a very recent selective sweep, because an intervening gene, Vmn1r71, shows significant intra(sub)specific polymorphism but no inter(sub)specific divergence in its nucleotide sequence. We discuss alternative explanations of these observations, for example that Abpa27 and Vmn1r67 are coevolving as signal and receptor to reinforce subspecies hybridization barriers or that the unusually divergent Vmn1r67 allele was not a product of fast positive selection, but was derived from an introgressed allele, possibly from Mus spretus

    A Gel Probe Equilibrium Sampler for Measuring Arsenic Porewater Profiles and Sorption Gradients in Sediments: I. Laboratory Development

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    A gel probe equilibrium sampler has been developed to study arsenic (As) geochemistry and sorption behavior in sediment porewater. The gels consist of a hydrated polyacrylamide polymer, which has a 92% water content. Two types of gels were used in this study. Undoped (clear) gels were used to measure concentrations of As and other elements in sediment porewater. The polyacrylamide gel was also doped with hydrous ferric oxide (HFO), an amorphous iron (Fe) oxyhydroxide. When deployed in the field, HFO-doped gels introduce a fresh sorbent into the subsurface thus allowing assessment of in situ sorption. In this study, clear and HFO-doped gels were tested under laboratory conditions to constrain the gel behavior prior to field deployment. Both types of gels were allowed to equilibrate with solutions of varying composition and re-equilibrated in acid for analysis. Clear gels accurately measured solution concentrations (±1%), and As was completely recovered from HFO-doped gels (±4%). Arsenic speciation was determined in clear gels through chromatographic separation of the re-equilibrated solution. For comparison to speciation in solution, mixtures of As(III) and As(V) adsorbed on HFO embedded in gel were measured in situ using X-ray absorption spectroscopy (XAS). Sorption densities for As(III) and As(V) on HFO embedded in gel were obtained from sorption isotherms at pH 7.1. When As and phosphate were simultaneously equilibrated (in up to 50-fold excess of As) with HFO-doped gels, phosphate inhibited As sorption by up to 85% and had a stronger inhibitory effect on As(V) than As(III). Natural organic matter (>200 ppm) decreased As adsorption by up to 50%, and had similar effects on As(V) and As(III). The laboratory results provide a basis for interpreting results obtained by deploying the gel probe in the field and elucidating the mechanisms controlling As partitioning between solid and dissolved phases in the environment

    Incorporating consumer cooperatives in Missouri

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    Investment Behavior and the Small Firm Effect

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    Our purpose in this review is to develop one explanation of market behavior which is consistent with the many empirical findings that appear to be inconsistent with the market efficiency hypothesis. To date, researchers have attempted to reconcile their empirical results with market efficiency based on either measurement error or structural inefficiencies. We propose a different approach to market efficiency. We posit that the empirical findings previous researchers report are by their nature ex post, and are a direct result of a market which is best described as efficient. We develop a model and provide a simulation to support this explanation

    Moxifloxacin and bilateral acute iris transillumination

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    Recent publications have alerted clinicians to a syndrome of uveitic transilluminating iris depigmentation associated with systemic fluoroquinolones and other antibiotics. Bilateral acute iris transillumination, which is associated with loss of the iris pigment epithelium and results in iris transillumination, differs from the previously described bilateral acute depigmentation of the iris, which is associated with atrophy of the iris stroma without transillumination. We present a case of fluoroquinolone-associated uveitis with anterior segment optical coherence tomography imaging to highlight some observations about this syndrome. We interpret pharmacokinetic data to help explain why oral, but not topical, moxifloxacin may cause fluoroquinolone-associated uveitis

    Endovascular repair of ruptured abdominal aortic aneurysm: A strategy in need of definitive evidence

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    IntroductionEndovascular strategies have been increasingly used to manage patients with ruptured abdominal aortic aneurysm (AAA) in an attempt to improve patient survival. We analyzed the evidence to support such an approach.MethodsWe performed a systematic literature review of endovascular aneurysm repair (EVAR) of ruptured AAA from 1994 to 2009. The literature analyzed included systematic reviews and population-based studies of ruptured AAA.ResultsSeven systematic reviews were identified, all demonstrating from published data that patients with EVAR of ruptured AAA had significantly reduced mortality compared with controls. Six recently published population-based studies from the United States demonstrated low mortality rates associated with EVAR; however, only a small proportion of ruptured AAAs were treated by EVAR. Systematic reviews and population-based studies both raised concerns about patient selection and publication bias. Two randomized trials are in progress, and one is due to commence 2009.ConclusionsThe outcome of EVAR in a nonselected patient population remains unknown. One or more definitive randomized trials could provide the level I evidence to resolve these issues

    Parent-Focused Childhood Obesity Intervention Improves Family Functioning and Children\u27s Well-Being

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    An Extension-implemented parent-focused childhood obesity intervention designed to improve family functioning around healthful eating and exercise was evaluated. Thirty-six parents and their children, aged 5–13, were randomized to a 12-week intervention condition or control condition. Intervention parents, compared to control group parents, felt more confident in promoting children\u27s healthful eating and exercise, worried less about their children\u27s weight, and engaged in fewer counterproductive parenting behaviors. The children of these parents, as compared to children of control group parents, lost weight and displayed better social-emotional functioning. These results highlight Extension\u27s important role in disseminating evidence-based childhood obesity interventions

    Cultural and Contextual Adaptation of a Childhood Obesity Preventive Intervention Program

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    This article describes the adaptation of a parent-focused evidence-based childhood obesity intervention program for implementation by county-based Extension educators in coordination with school district personnel in rural Pennsylvania. The Lifestyle Positive Parenting Program was designed and evaluated in Australia in clinical settings. Several minor and more serious adaptations, such as featured recipes and content of follow-up telephone calls, were made so that the program would be more appropriate for and appealing to target families. Conceptual issues regarding the adaptation of evidence-based programs are reviewed

    Accountability by Design: Moving Primary Care Reform Ahead in Alberta

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    Health-care reform is perennially popular in Alberta, but reality doesn’t match the rhetoric. Government has invested more than $700 million in Primary Care Networks — with little beyond anecdotal evidence of the value achieved with this investment. As the province redirects primary care to Family Care Clinics, the authors assert that simply tinkering with one part of the system is not the answer: health care must change on a system-wide basis. Drawing on the experiences of frontline staff and a rich body of literature, the authors present their vision for integrated team-based primary care, designed to be accountable to meet the needs of populations. This will require governance that makes primary care the hub of the system, and brings together government and health-services leadership to support the integration of primary and specialty care. There are shared accountabilities for achieving primary care that exhibits the attributes of high performing primary care systems, and these exist at multiple levels, from individuals seeking primary care, up to and including government. The authors make these accountabilities explicit, and outline strategies to secure their achievement that include system redesign, service delivery redesign and payment reform. All of this demands whole-system reform focused on primary care, and it won’t be easy. There are plenty of vested interests at stake, and a truly transformative vision requires buy-in at every level. However, Alberta’s rapidly growing and aging population makes it more urgent than ever to realize such a vision. This paper offers guidelines to spark the fresh thinking required
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