1,820 research outputs found

    Hadronic Decays of Charm

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    Recent hadronic charm decay results from fixed-target experiments are presented. New measurements of the D0 to K-K+K-pi+ branching ratio are shown as are recent results from Dalitz plot fits to D+ to K-K+pi+, pi+pi-pi+, K-pi+pi+, K+pi-pi+ and D_s+ to pi+pi-pi+, K+pi-pi+. These fits include measurements of the masses and widths of several light resonances as well as strong evidence for the existence of two light scalar particles, the pipi resonance sigma and the Kpi resonance kappa.Comment: 8 pages, 9 figures, to appear in the proceedings for the 9th International Symposium on Heavy Flavors, Caltech, Pasadena, 10-13 Sept. 200

    D0D^0--Dˉ0\bar{D}{}^0 hadronic mixing and DCS decays from FOCUS

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    We present an analysis of the decay D0K+πD^0 \to K^+\pi^- from FOCUS. From a sample of 234 events we find a branching ratio of Γ(D0K+π)Γ(D0Kπ+)=(0.4300.061+0.062±0.031)\frac{\Gamma(D^0 \to K^+\pi^-)}{\Gamma(D^0 \to K^-\pi^+)} = (0.430^{+0.062}_{-0.061}\pm 0.031)% under the assumption of no mixing and no CP violation. We also present limits on charm mixing.Comment: Proceedings from talk at 2004 DPF Meeting at University of California, Riversid

    Pentaquark searches at FOCUS

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    We find no evidence for high-energy photoproduction of pentaquarks at 1540 MeV/c2c^2, 1862 MeV/c2c^2, or 3099 MeV/c2c^2 using decay modes pKS0pK_S^0, Ξπ\Xi^-\pi^-, and D()pD^{(*)-}p, respectively.Comment: Proceedings from talk at 2004 DPF Meeting at University of California, Riversid

    Visual effects of wood on thermal perception of interior environments

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    There is a general consensus, supported by preliminary evidence, that exposed wood improves human perception of thermal comfort, though this idea has yet to be supported by meaningful effect sizes. This study sought to quantify human perception of thermal comfort of wood materials in a controlled laboratory setting. Participants experienced one of two wall treatments: exposed wooden wall panels and white-painted walls in a thermal environment set directly between "neutral” and "slightly warm” (81.5°F, 4Q%RH, PMV +Q.5). We hypothesized that participants exposed to the wood walls would gauge their thermal preference to be closer to neutral than that of participants who experienced the same thermal environment but with the white wall treatment. Wood was found to have a significant and moderate effect on thermal comfort, with the mean response of the participants who received the wood wall treatment being thermally preferable over that of the white wall (wood wall: M = Q.46, SD = Q.56; white wall: M = Q.68, SD = Q.51; p<Q.Q1)

    Evaluating Volatile Organic Compound Emissions from Cross-Laminated Timber Bonded with a Soy-Based Adhesive

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    Volatile organic compound (VOC) emissions from indoor sources are large determinants of the indoor air quality (IAQ) and occupant health. Cross-laminated timber (CLT) is a panelized engineered wood product often left exposed as an interior surface finish. As a certified structural building product, CLT is currently exempt from meeting VOC emission limits for composite wood products and confirming emissions through California Department of Public Health (CDPH) Standard Method testing. In this study, small chamber testing was conducted to evaluate VOC emissions from three laboratory-produced CLT samples: One bonded with a new soy-based cold-set adhesive; a second bonded with a commercially available polyurethane (PUR) adhesive; and the third assembled without adhesive using dowels. A fourth commercially-produced eight-month-old sample bonded with melamine formaldehyde (MF) adhesive was also tested. All four samples were produced with Douglas-fir. The test results for the three laboratory-produced samples demonstrated VOC emissions compliance with the reference standard. The commercially-produced and aged CLT sample bonded with MF adhesive did not meet the acceptance criterion for formaldehyde of ≤9.0 µg/m3. The estimated indoor air concentration of formaldehyde in an office with the MF sample was 54.4 µg/m3; the results for the soy, PUR, and dowel samples were all at or below 2.5 µg/m3

    Implementing a Volunteer-Match Service: Fostering Relationships between Al Akhawayn University and Local Non Governmental Organizations

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    At Al Akhawayn University in Ifrane (AUI), students are required to do community service, but AUI has no centralized way for students to find service projects in the community that stimulate their interests. The goal of this project is to improve the nature of volunteering at the university by building relationships between AUI and non-governmental organizations using a volunteer-match website as a tool. These relationships serve to expand the volunteer program at AUI and broaden the impact of volunteer work on the community. Using information from student focus groups and NGO interviews, we established a plan of implementation for this new volunteer-match service as well as recommendations to our sponsor

    A Novel VOC Breath Tracer Method to Evaluate Indoor Respiratory Exposures in the Near- and far-fields; implications for the spread of respiratory viruses

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    Background Several studies suggest that far-field transmission (\u3e6 ft) explains a significant number of COVID-19 superspreading outbreaks. Objective Therefore, quantifying the ratio of near- and far-field exposure to emissions from a source is key to better understanding human-to-human airborne infectious disease transmission and associated risks. Methods In this study, we used an environmentally-controlled chamber to measure volatile organic compounds (VOCs) released from a healthy participant who consumed breath mints, which contained unique tracer compounds. Tracer measurements were made at 0.76 m (2.5 ft), 1.52 m (5 ft), 2.28 m (7.5 ft) from the participant, as well as in the exhaust plenum of the chamber. Results We observed that 0.76 m (2.5 ft) trials had ~36–44% higher concentrations than other distances during the first 20 minutes of experiments, highlighting the importance of the near-field exposure relative to the far-field before virus-laden respiratory aerosol plumes are continuously mixed into the far-field. However, for the conditions studied, the concentrations of human-sourced tracers after 20 minutes and approaching the end of the 60-minute trials at 0.76 m, 1.52 m, and 2.28 m were only ~18%, ~11%, and ~7.5% higher than volume-averaged concentrations, respectively. Significance This study suggests that for rooms with similar airflow parameters disease transmission risk is dominated by near-field exposures for shorter event durations (e.g., initial 20–25-minutes of event) whereas far-field exposures are critical throughout the entire event and are increasingly more important for longer event durations

    Evaluating Volatile Organic Compound Emissions from Cross-Laminated Timber Bonded with a Soy-Based Adhesive

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    11 pagesVolatile organic compound (VOC) emissions from indoor sources are large determinants of the indoor air quality (IAQ) and occupant health. Cross-laminated timber (CLT) is a panelized engineered wood product often left exposed as an interior surface finish. As a certified structural building product, CLT is currently exempt from meeting VOC emission limits for composite wood products and confirming emissions through California Department of Public Health (CDPH) Standard Method testing. In this study, small chamber testing was conducted to evaluate VOC emissions from three laboratory-produced CLT samples: One bonded with a new soy-based cold-set adhesive; a second bonded with a commercially available polyurethane (PUR) adhesive; and the third assembled without adhesive using dowels. A fourth commercially-produced eight-month-old sample bonded with melamine formaldehyde (MF) adhesive was also tested. All four samples were produced with Douglas-fir. The test results for the three laboratory-produced samples demonstrated VOC emissions compliance with the reference standard. The commercially-produced and aged CLT sample bonded with MF adhesive did not meet the acceptance criterion for formaldehyde of ≤9.0 μg/m3. The estimated indoor air concentration of formaldehyde in an office with the MF sample was 54.4 μg/m3; the results for the soy, PUR, and dowel samples were all at or below 2.5 μg/m3.This research was funded by the U.S. Department of Agriculture’s Agricultural Research Service [USDA ARS Agreement 58-0204-6-002]
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