1,162 research outputs found

    Temporal Analysis of Floodplain Deposition Using Urban Pollution Stratigraphy, Wilson Creek, SW Missouri

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    Alluvial sediments record both hydrologic changes and variations of sediment quality affecting watersheds. This study uses urban pollution signatures as temporal tracers to date alluvial deposits along Wilson Creek located within Wilson’s Creek National Battlefield Park in southwestern Missouri. The creek drains Springfield, the third largest city in the state, which was settled in 1833. This study has three main objectives: (1) review historical documents to develop a pollution history for the watershed; (2) determine if there is a correlation between heavy metal and phosphorus concentrations in sediment cores and the timing of release of those elements into the creek system; and (3) evaluate stratigraphic relationships of pollutant trends to describe the history and rates of floodplain sedimentation. Samples were collected from thirteen core locations across a terrace-floodplain transect and analyzed for geochemistry, organic content, pH, Munsell color, and texture. 137Cesium dating was used to identify the 1954 and 1964 layers and aerial photography was used to determine changes in stream location and morphology since 1936. Results show that (1) post-World War II urban pollution signatures are evident in the top 50 cm of floodplain deposits, with significant changes in concentrations with depth of Pb, Hg, Ag, Cu, Zn, and P; (2) some of these trends can be correlated with changes in land use patterns in Springfield and known industrial developments, toxic chemical releases, and wastewater treatment plant operations; (3) sedimentation rates averaged 0.8 cm/yr from 1861-1954, 2.5 cm/yr from 1954-1964, and 0.4 cm/yr from 1964-2002, with an overall average of 0.8 cm/yr

    Ecological patterns of seed microbiome diversity, transmission, and assembly

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    Seeds are involved in the transmission of microorganisms from one plant generation to another and consequently act as the initial inoculum for the plant microbiota. The purpose of this mini-review is to provide an overview of current knowledge on the diversity, structure and role of the seed microbiota. The relative importance of the mode of transmission (vertical vs horizontal) of the microbial entities composing the seed microbiota as well as the potential connections existing between seed and other plant habitats such as the anthosphere and the spermosphere is discussed. Finally the governing processes (niche vs neutral) involved in the assembly and the dynamics of the seed microbiota are examined

    Incorporating Crystallographic Orientation in the Development of Resonant Ultrasound Spectroscopy

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    Resonant ultrasound spectroscopy (RUS) measures the mechanical resonance frequencies of solids and uses computational algorithm to extract a complete set of elastic constants. One of the advantages of the RUS method is its applicability to small single crystals. In the past two decades, the RUS technique has gained more acceptance as a nondestructive method to measure elastic properties. The goal of this project is to measure elastic properties of micro pillars without free-free boundary conditions and arbitrary crystallographic orientations. To achieve this goal we need a capability to measure elastic constants of single crystals with arbitrary crystal orientation relative to sample geometry. The inherent assumptions in conventional RUS algorithm include free boundary condition on the specimen faces and the faces of the specimens are normal/parallel to the principal crystallographic axes. To meet these requirements, a time consuming sample preparation, involving multiple inspections of x-ray Laue back reflection to check the crystallographic orientation, is followed. Such an intensive method is not suitable for many samples in engineering applications. To estimate the elastic constants of such samples, a new RUS algorithm has been developed that incorporates the sample crystallographic orientation expressed in terms of Euler angles. The power of the modified RUS algorithm is demonstrated by applying it to estimate the elastic constants of cubic and hexagonal crystal structure samples with known orientation. The results are compared with literature values. Potential application of the method include estimation of elastic constants and their use as input parameters in models that predicts the mechanical behavior of materials for engineering applications is discussed

    Treatment Buddies Improve Clinic Attendance among Women but Not Men on Antiretroviral Therapy in the Nyanza Region of Kenya.

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    Background. Kenyan antiretroviral (ART) guidelines encourage treatment buddies (TBy) to maximize treatment adherence. This study examined the effect of TBys on clinic attendance in men and women on ART. Methods. This retrospective cohort study included all adult patients initiating ART from August 2007 to December 2011 at four health facilities in Kenya. Data were abstracted from electronic medical records and analyzed using Poisson regression. Results. Of 2,430 patients, 2,199 (91%) had a TBy. Relationship between TBy and clinic attendance differed in females and males (interaction p = 0.09). After demographic and clinic factor adjustment, females with a TBy were 28% more likely to adhere to all appointments than those without (adjusted aRR = 1.28; 95% CI 1.08-1.53), whereas males were no more likely to adhere (aRR = 1.01; 95% CI 0.76-1.32). Males reported partner/spouse (33%) or brother (11%) as the TBy while females reported sister (17%), partner/spouse (14%), or another family member (12%). Multivariable analysis found no association between clinic attendance and TBy relationship in either gender. Conclusion. Clinic attendance was higher among women with TBys but not men. Results support TBys to help women achieve ART success; alternate strategies to bolster TBy benefits are needed for men

    Integration of HIV Care with Primary Health Care Services: Effect on Patient Satisfaction and Stigma in Rural Kenya.

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    HIV departments within Kenyan health facilities are usually better staffed and equipped than departments offering non-HIV services. Integration of HIV services into primary care may address this issue of skewed resource allocation. Between 2008 and 2010, we piloted a system of integrating HIV services into primary care in rural Kenya. Before integration, we conducted a survey among returning adults ≥18-year old attending the HIV clinic. We then integrated HIV and primary care services. Three and twelve months after integration, we administered the same questionnaires to a sample of returning adults attending the integrated clinic. Changes in patient responses were assessed using truncated linear regression and logistic regression. At 12 months after integration, respondents were more likely to be satisfied with reception services (adjusted odds ratio, aOR 2.71, 95% CI 1.32-5.56), HIV education (aOR 3.28, 95% CI 1.92-6.83), and wait time (aOR 1.97 95% CI 1.03-3.76). Men's comfort with receiving care at an integrated clinic did not change (aOR = 0.46 95% CI 0.06-3.86). Women were more likely to express discomfort after integration (aOR 3.37 95% CI 1.33-8.52). Integration of HIV services into primary care services was associated with significant increases in patient satisfaction in certain domains, with no negative effect on satisfaction

    Integration of family planning services into HIV care clinics: Results one year after a cluster randomized controlled trial in Kenya.

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    OBJECTIVES:To determine if integration of family planning (FP) and HIV services led to increased use of more effective contraception (i.e. hormonal and permanent methods, and intrauterine devices) and decreased pregnancy rates. DESIGN:Cohort analysis following cluster randomized trial, when the Kenya Ministry of Health led integration of the remaining control (delayed integration) sites and oversaw integrated services at the original intervention (early integration) sites. SETTING:Eighteen health facilities in Kenya. SUBJECTS:Women aged 18-45 receiving care: 5682 encounters at baseline, and 11628 encounters during the fourth quarter of year 2. INTERVENTION:"One-stop shop" approach to integrating FP and HIV services. MAIN OUTCOME MEASURES:Use of more effective contraceptive methods and incident pregnancy across two years of follow-up. RESULTS:Following integration of FP and HIV services at the six delayed integration clinics, use of more effective contraception increased from 31.7% to 44.2% of encounters (+12.5%; Prevalence ratio (PR) = 1.39 (1.19-1.63). Among the twelve early integration sites, the proportion of encounters at which women used more effective contraceptive methods was sustained from the end of the first to the second year of follow-up (37.5% vs. 37.0%). Pregnancy incidence including all 18 integrated sites in year two declined in comparison to the control arm in year one (rate ratio: 0.72; 95% CI 0.60-0.87). CONCLUSIONS:Integration of FP services into HIV clinics led to a sustained increase in the use of more effective contraceptives and decrease in pregnancy incidence 24 months following implementation of the integrated service model. TRIAL REGISTRATION:ClinicalTrials.gov NCT01001507

    Practice transformations to optimize the delivery of HIV primary care in community healthcare settings in the United States: A program implementation study.

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    BackgroundThe United States HIV care workforce is shrinking, which could complicate service delivery to people living with HIV (PLWH). In this study, we examined the impact of practice transformations, defined as efficiencies in structures and delivery of care, on demonstration project sites within the Workforce Capacity Building Initiative, a Health Resources and Services Administration (HRSA) Ryan White HIV/AIDS Program Special Projects of National Significance (SPNS).Methods and findingsData were collected at 14 demonstration project sites in 7 states and the District of Columbia. Organizational assessments were completed at sites once before and 4 times after implementation. They captured 3 transformation approaches: maximizing the HIV care workforce (efforts to increase the number of existing healthcare workforce members involved in the care of PLWH), share-the-care (team-based care giving more responsibility to midlevel providers and staff), and enhancing client engagement in primary HIV care to reduce emergency and inpatient care (e.g., care coordination). We also obtained Ryan White HIV/AIDS Program Services Reports (RSRs) from sites for calendar years (CYs) 2014-2016, corresponding to before, during, and after transformation. The RSR include data on client retention in HIV care, prescription of antiretroviral therapy (ART), and viral suppression. We used generalized estimating equation (GEE) models to analyze changes among sites implementing each practice transformation approach. The demonstration projects had a mean of 18.5 prescribing providers (SD = 23.5). They reported data on more than 13,500 clients per year (mean = 969/site, SD = 1,351). Demographic characteristics remained similar over time. In 2014, a majority of clients were male (71% versus 28% female and 0.2% transgender), with a mean age of 47 (interquartile range [IQR] 37-54). Racial/ethnic characteristics (48% African American, 31% Hispanic/Latino, 14% white) and HIV risk varied (31% men who have sex with men; 31% heterosexual men and women; 7% injection drug use). A substantial minority was on Medicaid (41%). Across sites, there was significant uptake in practices consistent with maximizing the HIV care workforce (18% increase, p < 0.001), share-the-care (25% increase, p < 0.001), and facilitating patient engagement in HIV primary care (13% increase, p < 0.001). There were also significant improvements over time in retention in HIV care (adjusted odds ratio [aOR] = 1.03; 95% confidence interval [CI] 1.02-1.04; p < 0.001), ART prescription levels (aOR = 1.01; 95% CI 1.00-1.01; p < 0.001), and viral suppression (aOR = 1.03; 95% CI 1.02-1.04; p < 0.001). All outcomes improved at sites that implemented transformations to maximize the HIV care workforce or improve client engagement. At sites that implemented share-the-care practices, only retention in care and viral suppression outcomes improved. Study limitations included use of demonstration project sites funded by the Ryan White HIV/AIDS Program (RWHAP), which tend to have better HIV outcomes than other US clinics; varying practice transformation designs; lack of a true control condition; and a potential Hawthorne effect because site teams were aware of the evaluation.ConclusionsIn this study, we found that practice transformations are a potential strategy for addressing anticipated workforce challenges among those providing care to PLWH. They hold the promise of optimizing the use of personnel and ensuring the delivery of care to all in need while potentially enhancing HIV care continuum outcomes

    Assembly of seed-associated microbial communities within and across successive plant generations

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    Background and aims Seeds are involved in the transmission of microorganisms from one plant generation to another and consequently may act as the initial inoculum source for the plant microbiota. In this work, we assessed the structure and composition of the seed microbiota of radish (Raphanus sativus) across three successive plant generations. Methods Structure of seed microbial communities were estimated on individual plants through amplification and sequencing of genes that are markers of taxonomic diversity for bacteria (gyrB) and fungi (ITS1). The relative contribution of dispersal and ecological drift in inter-individual fluctuations were estimated with a neutral community model. Results Seed microbial communities of radish display a low heritability across plant generations. Fluctuations in microbial community profiles were related to changes in community membership and composition across plant generations, but also to variation between individual plants. Ecological drift was an important driver of the structure of seed bacterial communities, while dispersal was involved in the assembly of the fungal fraction of the seed microbiota. Conclusions These results provide a first glimpse of the governing processes driving the assembly of the seed microbiota

    Finite Element Modeling of Resonance in Polycrystalline Materials for Resonance Ultrasound Spectroscopy

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    Validation of models that predict the performance of aerospace engine materials depends on the ability to obtain accurate single crystal elastic constants. Resonance Ultrasound Spectroscopy (RUS) is a nondestructive technique in which the natural resonances of a material are utilized to obtain these constants. Traditional RUS utilizes an analytic approach to determine the resonance frequencies of a specimen given an initial guess set of elastic constants. A nonlinear optimization process then fits the elastic constants to experimentally measured data. This approach is limited both in its ability to handle specimens with complex geometry and to handle polycrystalline materials. These more complex scenarios can be approached by utilizing a finite element forward model to obtain sample resonances. A finite element forward model is being developed utilizing COMSOL Multiphysics to compute specimen resonance frequencies. Elastic constants are obtained utilizing a bounded nonlinear optimization routine in MATLAB by way of COMSOL\u27s LiveLink for MATLAB interface. Validation of this forward model has been performed on single crystal specimens, including a nickel superalloy parallelepiped and a fused silica cylinder with a chamfer, ultimately producing lower residual error after optimization than the traditional RUS approach. Model validation is also being performed on a Nickel Aluminide (NiAl) bicrystal. This paper presents the details of this validation process. Also presented is an examination of error sources and the impact they can play in the ability to accurately obtain elastic constants
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