3,302 research outputs found

    Investigating the Morphological and Genetic Divergence of Arctic Char \u3ci\u3e(Salvelinus alpinus)\u3c/i\u3e Populations in Lakes of Arctic Alaska

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    Polymorphism facilitates coexistence of divergent morphs (e.g., phenotypes) of the same species by minimizing intraspecific competition, especially when resources are limiting. Arctic char (Salvelinus sp.) are a Holarctic fish often forming morphologically, and sometimes genetically, divergent morphs. In this study, we assessed the morphological and genetic diversity and divergence of 263 individuals from seven populations of arctic char with varying length-frequency distributions across two distinct groups of lakes in northern Alaska. Despite close geographic proximity, each lake group occurs on landscapes with different glacial ages and surface water connectivity, and thus was likely colonized by fishes at different times. Across lakes, a continuum of physical (e.g., lake area, maximum depth) and biological characteristics (e.g., primary productivity, fish density) exists, likely contributing to characteristics of present-day char populations. Although some lakes exhibit bimodal size distributions, using model-based clustering of morphometric traits corrected for allometry, we did not detect morphological differences within and across char populations. Genomic analyses using 15,934 SNPs obtained from genotyping by sequencing demonstrated differences among lake groups related to historical biogeography, but within lake groups and within individual lakes, genetic differentiation was not related to total body length. We used PERMANOVA to identify environmental and biological factors related to observed char size structure. Significant predictors included water transparency (i.e., a primary productivity proxy), char density (fish·ha-1), and lake group. Larger char occurred in lakes with greater primary production and lower char densities, suggesting less intraspecific competition and resource limitation. Thus, char populations in more productive and connected lakes may prove more stable to environmental changes, relative to food-limited and closed lakes, if lake productivity increases concomitantly. Our findings provide some of the first descriptions of genomic characteristics of char populations in arctic Alaska, and offer important consideration for the persistence of these populations for subsistence and conservation

    Description of an advanced practice nursing consultative model to reduce restrictive siderail use in nursing homes

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    Researchers have demonstrated that the use of physical restraints in nursing homes can be reduced, particularly where advanced practice nurses (APNs) are utilized. We examined the link between APN practice, siderail reduction, and the costs of siderail alternatives in 273 residents in four Philadelphia nursing homes. The majority of participants were cognitively and physically impaired with multiple co-morbidities. APNs recommended a total of 1,275 siderail-alternative interventions aimed at reducing fall risk. The median cost of siderail alternatives to prevent falls per resident was $135. Residents with a fall history experienced a significantly higher cost of recommendation compared to non-fallers. Findings suggest that an APN consultation model can effectively be implemented through comprehensive, individualized assessment without incurring substantial costs to the nursing home. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 131–140, 2007Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56001/1/20185_ftp.pd

    Anti-citrullinated peptide autoantibodies, human leukocyte antigen shared epitope and risk of future rheumatoid arthritis: a nested case–control study

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    Introduction: The aim of this study was to characterize anti-citrullinated peptide antibody (ACPA) serostatus in pre-clinical rheumatoid arthritis (RA) with and without Human Leukocyte Antigen-Shared Epitope (HLA-SE) alleles. Methods: We identified 192 women in the Nurses’ Health Study cohorts with blood samples obtained 4 months to 17 years prior to medical record-confirmed RA diagnosis. Three controls were selected matched on age, cohort, menopausal status and post-menopausal hormone use. Reactivities to 18 ACPAs were measured using a custom BioPlex platform. We used conditional logistic regression to calculate the relative risk (RR) of RA for any ACPA-positive and peptide-specific ACPA-positive and examined RRs by time between blood draw and RA onset. Measures of multiplicative and additive interaction between any ACPA-positive and HLA-SE were calculated. Results: All ACPAs by peptide groups were significantly associated with RA risk, RRs ranged from 4.7 to 11.7. The association between ACPA and RA varied over time with the strongest association in those with blood draw less than 5 years before onset (RR 17.0 [95% CI 5.8 to 53.7]) and no association 10 or more years prior to onset (RR 1.4 [95% CI 0.5 to 4.3]). Individuals with both HLA-SE and any ACPA-positive had the highest risk of RA. HLA-SE-positive RA cases showed reactivity to more ACPA types than HLA-SE negative (χ2 test for trend, P = 0.01). Conclusions: There is increasing ACPA reactivity up to 10 years before RA onset with the strongest association within 5 years of RA onset. The magnitude of the response to ACPAs, in combination with the presence of HLA-SE, is most important for identifying those individuals with the highest risk of RA

    Barriers to colonoscopy in UK colorectal cancer screening programmes: Qualitative interviews with ethnic minority groups

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    OBJECTIVE: People from ethnic minority backgrounds are less likely to attend colonoscopy, following faecal immunochemical test screening, and are more likely to be diagnosed with colorectal cancer at an advanced stage as a result. The aim of this research was to explore the barriers and facilitators to attending colonoscopy, perceived by ethnic minority groups living in the United Kingdom. METHODS: Semi-structured online and telephone interviews were conducted with thirty men and women of Black-African(n=5), Black-Caribbean(n=5), South Asian(n=10) and White British(n=10) descent. Participants were eligible for screening, but had not necessarily been invited for colonoscopy. All interviews were conducted in the participant's first language and were assessed using Framework-analysis, in line with a conceptual framework developed from previous interviews with healthcare professionals. RESULTS: Five thematic groups of barriers and facilitators were developed: 'Locus of control', 'Cultural attitudes and beliefs', 'Individual beliefs, knowledge and personal experiences with colonoscopy and cancer', 'Reliance on family and friends' and 'Health concerns'. Differences were observed, between ethnic groups, for: 'Locus of control', 'Cultural attitudes and beliefs' and 'Reliance on family and friends'. Black and South Asian participants frequently described the decision to attend colonoscopy as lying with 'God' (Muslims, specifically), 'the doctor', or 'family' (Locus of control). Black and South Asian participants also reported relying on friends and family for 'language, transport and emotional support' (Reliance on family and friends). Black-African participants, specifically, described cancer as 'socially taboo' (Cultural attitudes and beliefs). CONCLUSIONS: The results highlight several targets for culturally-tailored interventions to make colonoscopy more equitable. This article is protected by copyright. All rights reserved

    Legionella pneumophila Infection of Drosophila S2 Cells Induces Only Minor Changes in Mitochondrial Dynamics.

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    During infection of cells by Legionella pneumophila, the bacterium secretes a large number of effector proteins into the host cell cytoplasm, allowing it to alter many cellular processes and make the vacuole and the host cell into more hospitable environments for bacterial replication. One major change induced by infection is the recruitment of ER-derived vesicles to the surface of the vacuole, where they fuse with the vacuole membrane and prevent it from becoming an acidified, degradative compartment. However, the recruitment of mitochondria to the region of the vacuole has also been suggested by ultrastructural studies. In order to test this idea in a controlled and quantitative experimental system, and to lay the groundwork for a genome-wide screen for factors involved in mitochondrial recruitment, we examined the behavior of mitochondria during the early stages of Legionella pneumophila infection of Drosophila S2 cells. We found that the density of mitochondria near vacuoles formed by infection with wild typeLegionella was not different from that found in dotA– mutant-infected cells during the first 4 hours after infection. We then examined 4 parameters of mitochondrial motility in infected cells: velocity of movement, duty cycle of movement, directional persistence and net direction. In the 4 hours following infection, most of these measures were indistinguishable between wild type and dotA−.infection. However, wild type Legionella did induce a modest shift in the velocity distribution toward faster movement compared dotA− infection, and a small downward shift in the duty cycle distribution. In addition, wild type infection produced mitochondrial movement that was biased in the direction of the bacterial vacuole relative to dotA-, although not enough to cause a significant accumulation within 10 um of the vacuole. We conclude that in this host cell, mitochondria are not strongly recruited to the vacuole, nor is their motility dramatically affected

    A Leishmania secretion system for the expression of major ampullate spidroin mimics

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    Spider major ampullate silk fibers have been shown to display a unique combination of relatively high fracture strength and toughness compared to other fibers and show potential for tissue engineering scaffolds. While it is not possible to mass produce native spider silks, the potential ability to produce fibers from recombinant spider silk fibers could allow for an increased innovation rate within tissue engineering and regenerative medicine. In this pilot study, we improved upon a prior fabrication route by both changing the expression host and additives to the fiber pulling precursor solution to improve the performance of fibers. The new expression host for producing spidroin protein mimics, protozoan parasite Leishmania tarentolae, has numerous advantages including a relatively low cost of culture, rapid growth rate and a tractable secretion pathway. Tensile testing of hand pulled fibers produced from these spidroin-like proteins demonstrated that additives could significantly modify the fiber’s mechanical and/or antimicrobial properties. Cross-linking the proteins with glutaraldehyde before fiber pulling resulted in a relative increase in tensile strength and decrease in ductility. The addition of ampicillin into the spinning solution resulted in the fibers being able to inhibit bacterial growth

    Developmental Considerations for Substance Use Interventions From Middle School Through College

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    This article summarizes a symposium organized by Dr. Elizabeth D’Amico and presented at the 2004 Annual Meeting of the Research Society on Alcoholism in Vancouver, Canada. The four presentations illustrate the importance of creating substance use interventions that are developmentally appropriate for youth. They represent innovative approaches to working with preteens, teenagers, and young adults. Dr. D’Amico’s paper describes her research on the development of a voluntary brief intervention targeting alcohol use among middle school students. Findings indicated that by using school and community input, she was able to obtain a diverse a sample of youth across grades, sex, ethnicity, and substance use status. Dr. Ellickson’s paper describes her research on Project ALERT, a school-based prevention program for middle school youth. Her findings indicate that Project ALERT worked for students at all levels of risk (low, moderate, and high) and for all students combined. Dr. Wagner’s Teen Intervention Project was a ran-domized clinical trial to test the efficacy of a standardized Student Assistance Program for treating middle and high school students with alcohol and other drug problems. The study provided a unique opportunity to begin to examine how development may impact response to an alcohol or other drug intervention. Dr. Turrisi’s paper examined processes underlying the nature of the effects of a parent intervention on college student drinking tendencies. Findings suggested that the parent intervention seems to have its impact on student drinking by reducing the influence of negative communications and decreasing the susceptibility of influences from closest friends. Dr. Kim Fromme provided concluding remarks

    Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids

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    Citation: Ploetz, E. A., Karunaweera, S., & Smith, P. E. (2015). Experimental triplet and quadruplet fluctuation densities and spatial distribution function integrals for pure liquids. Journal of Chemical Physics, 142(4), 14. doi:10.1063/1.4905562Fluctuation solution theory has provided an alternative view of many liquid mixture properties in terms of particle number fluctuations. The particle number fluctuations can also be related to integrals of the corresponding two body distribution functions between molecular pairs in order to provide a more physical picture of solution behavior and molecule affinities. Here, we extend this type of approach to provide expressions for higher order triplet and quadruplet fluctuations, and thereby integrals over the corresponding distribution functions, all of which can be obtained from available experimental thermodynamic data. The fluctuations and integrals are then determined using the International Association for the Properties of Water and Steam Formulation 1995 (IAPWS-95) equation of state for the liquid phase of pure water. The results indicate small, but significant, deviations from a Gaussian distribution for the molecules in this system. The pressure and temperature dependence of the fluctuations and integrals, as well as the limiting behavior as one approaches both the triple point and the critical point, are also examined. (C) 2015 AIP Publishing LLC

    Parameterization of single-scattering albedo (SSA) and absorption Ångström exponent (AAE) with EC/OC for aerosol emissions from biomass burning

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    Single-scattering albedo (SSA) and absorption Ångström exponent (AAE) are two critical parameters in determining the impact of absorbing aerosol on the Earth\u27s radiative balance. Aerosol emitted by biomass burning represent a significant fraction of absorbing aerosol globally, but it remains difficult to accurately predict SSA and AAE for biomass burning aerosol. Black carbon (BC), brown carbon (BrC), and non-absorbing coatings all make substantial contributions to the absorption coefficient of biomass burning aerosol. SSA and AAE cannot be directly predicted based on fuel type because they depend strongly on burn conditions. It has been suggested that SSA can be effectively parameterized via the modified combustion efficiency (MCE) of a biomass burning event and that this would be useful because emission factors for CO and CO2, from which MCE can be calculated, are available for a large number of fuels. Here we demonstrate, with data from the FLAME-4 experiment, that for a wide variety of globally relevant biomass fuels, over a range of combustion conditions, parameterizations of SSA and AAE based on the elemental carbon (EC) to organic carbon (OC) mass ratio are quantitatively superior to parameterizations based on MCE. We show that the EC/OC ratio and the ratio of EC/(EC + OC) both have significantly better correlations with SSA than MCE. Furthermore, the relationship of EC/(EC + OC) with SSA is linear. These improved parameterizations are significant because, similar to MCE, emission factors for EC (or black carbon) and OC are available for a wide range of biomass fuels. Fitting SSA with MCE yields correlation coefficients (Pearson\u27s r) of ∼0.65 at the visible wavelengths of 405, 532, and 660 nm while fitting SSA with EC/OC or EC/(EC + OC) yields a Pearson\u27s r of 0.94-0.97 at these same wavelengths. The strong correlation coefficient at 405 nm (r = 0.97) suggests that parameterizations based on EC/OC or EC/(EC + OC) have good predictive capabilities even for fuels in which brown carbon absorption is significant. Notably, these parameterizations are effective for emissions from Indonesian peat, which have very little black carbon but significant brown carbon (SSA = 0.990 ± 0.001 at 532 and 660 nm, SSA = 0.937 ± 0.011 at 405 nm). Finally, we demonstrate that our parameterization based on EC/(EC + OC) accurately predicts SSA during the first few hours of plume aging with data from Yokelson et al. (2009) gathered during a biomass burning event in the Yucatán Peninsula of Mexico

    Families in Transition: The Lived Experience of Parenting a Transgender Child

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    This qualitative study explored parent’s experiences of their child undergoing gender transition. Data analysis yielded themes that begin to identify the complex nature and struggles parents face as they encounter the emotional and physical aspects of this transition. The focus is on the context of the family rather than the broader social context of school or community. The central question is: “What is the experience of parenting a transgender child?
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