3,178 research outputs found

    Expression of Human Microsomal Epoxide Hydrolase in Saccharomyces cerevisiae Reveals a Functional Role in Aflatoxin B1 Detoxification

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    The metabolism and genotoxicity of the carcinogenic mycotoxin, aflatoxin B1 (AFB), was studied in the lower eukaryotic yeast Saccharomyces cerevisiae. Recombinant strains of yeast were engineered to express human cDNAs for CYP1A1, CYP1A2, and microsomal epoxide hydrolase (mEH). Coexpression of mEH with CYP1A1 or CYP1A2 resulted in significant decreases in measurements of AFB genotoxicity. In cells expressing CYP1A2 and mEH, the level of AFB-DNA adducts was decreased by 50% relative to cells expressing CYP1A2 alone. Mitotic recombination, as assayed by gene conversion at thetrp5locus, was diminished by 50% or greater in cells coexpressing mEH and CYP1A2 compared to CYP1A2 alone. The mutagenicity of AFB in the Ames assay was also decreased by approximately 50% when AFB was incubated with microsomes containing CYP1A1 or CYP1A2 and mEH versus CYP1A1 or CYP1A2 alone. The biotransformation of AFB by CYPs is known to involve the generation of a reactive epoxide intermediate, AFB-8,9-epoxide, but previous direct biochemical and kinetic studies have failed to demonstrate any functional role for mEH in AFB detoxification. By reconstructing a metabolic pathway in intact yeast, we have shown, for the first time, that mEH may play a role in mitigating the carcinogenic effects of AF

    Ionospheric ion temperature climate and upper atmospheric long-term cooling

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    It is now recognized that Earth's upper atmosphere is experiencing a long-term cooling over the past several solar cycles. The potential impact of the cooling on societal activities is significant, but a fundamental scientific question exists regarding the drivers of the cooling. New observations and analyses provide crucial advances in our knowledge of these important processes. We investigate ionospheric ion temperature climatology and long-term trends using up-to-date large and consistent ground-based data sets as measured by multiple incoherent scatter radars (ISRs). The very comprehensive view provided by these unique observations of the upper atmospheric thermal status allows us to address drivers of strong cooling previously observed by ISRs. We use observations from two high-latitude sites at Sondrestrom (invariant latitude 73.2°N) from 1990 to 2015 and Chatanika/Poker Flat (invariant latitude 65.9°N) over the span of 1976–2015 (with a gap from 1983 to 2006). Results are compared to conditions at the midlatitude Millstone Hill site (invariant latitude 52.8°N) from 1968 to 2015. The aggregate radar observations have very comparable and consistent altitude dependence of long-term trends. In particular, the lower F region (<275 km) exhibits dayside cooling trends that are significantly higher (−3 to −1 K/yr at 250 km) than anticipated from model predictions given the anthropogenic increase of greenhouse gases. Above 275 km, cooling trends continue to increase in magnitude but values are strongly dependent on magnetic latitude, suggesting the presence of significant downward influences from nonneutral atmospheric processes.National Science Foundation (U.S.) (Awards AGS-1042569 and AGS-1343056

    On-Campus Occupational Therapy Clinic Enhances Student Professional Development and Understanding

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    Changing healthcare systems impact clinical sites that provide fieldwork for occupational therapy programs and require students to be prepared for the pace and demands of the clinical settings. Occupational therapy programs strive to enhance hands-on experiences in didactic curriculum to better prepare students for Level II fieldwork. An on-campus clinic course was implemented over two semesters with students engaging in the occupational therapy process with adult and pediatric clients from the community under the supervision of faculty. Student surveys and focus group data were analyzed over five years. Survey responses to open-ended question were triangulated with data from focus group results and themes were validated with quantitative survey data. The research explored the design of the on-campus clinic courses, the themes of the data analysis, and implications for learning opportunities with clients in an on-campus experience. The findings support the feasibility of implementing an on-campus clinic with positive student outcomes and enhanced faculty-student relationships that are sustainable over several years

    Evidence Considerations for Mobile Devices in the Occupational Therapy Process

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    Mobile app-based device utilization, including smartphones and handheld tablets, suggests a need to evaluate evidence to guide selection and implementation of these devices in the occupational therapy process. The purpose of the research was to explore the current body of evidence in relation to mobile app-based devices and to identify factors in the use of these devices throughout the occupational therapy process. Following review of available occupational therapy profession guidelines, assistive technology literature, and available mobile device research, practitioners using mobile app-based devices in occupational therapy should consider three areas: client needs, practitioner competence, and device factors. The purpose of this guideline is to identify factors in the selection and use of mobile app-based devices throughout the occupational therapy process based on available evidence. Considerations for mobile device implementation during the occupational therapy process is addressed, including evaluating outcomes needs, matching device with the client, and identifying support needs of the client

    Highly Ionized Potassium Lines in Solar X-ray Spectra and the Abundance of Potassium

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    The abundance of potassium is derived from X-ray lines observed during flares by the RESIK instrument on the solar mission CORONAS-F between 3.53 A and 3.57 A. The lines include those emitted by He-like K and Li-like K dielectronic satellites, which have been synthesized using the CHIANTI atomic code and newly calculated atomic data. There is good agreement of observed and synthesized spectra, and the theoretical behavior of the spectra with varying temperature estimated from the ratio of the two GOES channels is correctly predicted. The observed fluxes of the He-like K resonance line per unit emission measure gives log A(K) = 5.86 (on a scale log A(H) = 12), with a total range of a factor 2.9. This is higher than photospheric abundance estimates by a factor 5.5, a slightly greater enhancement than for other elements with first ionization potential (FIP) less than about 10 eV. There is, then, the possibility that enrichment of low-FIP elements in coronal plasmas depends weakly on the value of the FIP which for K is extremely low (4.34 eV). Our work also suggests that fractionation of elements to form the FIP effect occurs in the low chromosphere rather than higher up, as in some models.Comment: 14 pages, 3 figure

    Lesbian and bisexual women's experiences of sexuality-based discrimination and their appearance concerns

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    Lesbian and bisexual women frequently experience sexuality-based discrimination, which is often based on others' judgements about their appearance. This short article aims to explore whether there is a relationship between lesbian and bisexual women's experiences of sexuality-based discrimination and their satisfaction with the way that they look. Findings from an online survey suggest that discrimination is negatively related to appearance satisfaction for lesbian women, but not for bisexual women. It is argued that this difference exists because lesbian appearance norms are more recognisable and distinctive than bisexual women's appearance norms

    On-Campus Occupational Therapy Clinic: Exploring a Supervision Model for Level I Fieldwork Within Curriculum

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    This study explored how a revised on-campus occupational therapy clinic model impacted occupational therapy graduate student professional development and clinical practice educator confidence in areas related to the on-campus clinic environment, professionalism, student learning, and collaboration. Specifically, clinical practice educator and student confidence were compared through quantitative survey data across multiple cohorts and clinical educators. This data was used to triangulate qualitative findings from focus groups and open-ended survey questions. Analysis across five years of qualitative data revealed themes related to professionalism including time management, planning, feedback, observation, collaboration, and communication. Quantitative data analysis found significant differences between clinical practice educator and student confidence in clinic environment, professionalism, and learning in an on-campus clinic. No significance was found in collaboration. Students were more confident in their familiarity with the on-campus clinic routine than clinical practice educators. Familiarity with the clinic routine was also related to clinical practice educators’ confidence in supporting student learning for growth and change and resolving challenges that impede student learning. Feedback and communication were important in the students\u27 experiences with benefits and suggestions to improve feedback provided by students. Educators and practitioners interested in alternative Level I fieldwork opportunities can consider the implications for a collaborative supervision model in an on-campus clinic environment

    Effective permittivity of random plasmonic composites

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    An effective-medium theory (EMT) is developed to predict the effective permittivity \epsilon_eff of dense random dispersions of high optical-conductivity metals such as Ag, Au and Cu. Dependence of \epsilon_eff on the volume fraction \phi, a microstructure parameter \kappa related to the static structure factor and particle radius a is studied. In the electrostatic limit, the upper and lower bounds of \kappa correspond to Maxwell-Garnett and Bruggeman EMTs respectively. Finite size effects are significant when |\beta^2(ka/n)^3| becomes O(1) where \beta, k, and n denote the nanoparticle polarizability, wavenumber and matrix refractive index respectively. The coupling between the particle and effective medium results in a red-shift in the resonance peak, a non-linear dependence of \epsilon_eff on \phi, and Fano resonance in \epsilon_eff.Comment: Manuscript submitted to J. Opt. Soc. Am. B. 33 page
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