1,144 research outputs found

    Nighttime chemistry at a high altitude site above Hong Kong

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    Nighttime reactions of nitrogen oxides influence ozone, volatile organic compounds, and aerosol and are thus important to the understanding of regional air quality. Despite large emissions and rapid recent growth of nitrogen oxide concentrations, there are few studies of nighttime chemistry in China. Here we present measurements of nighttime nitrogen oxides, NO3 and N2O5, from a coastal mountaintop site in Hong Kong adjacent to the megacities of the Pearl River Delta region. This is the first study of nighttime chemistry from a site within the residual layer in China. Key findings include the following. First, highly concentrated urban NOx outflow from the Pearl River Delta region was sampled infrequently at night, with N2O5 mixing ratios up to 8 ppbv (1 min average) or 12 ppbv (1 s average) in nighttime aged air masses. Second, the average N2O5 uptake coefficient was determined from a best fit to the available steady state lifetime data as γ(N2O5) = 0.014 ± 0.007. Although this determination is uncertain due to the difficulty of separating N2O5 losses from those of NO3, this value is in the range of previous residual layer determinations of N2O5 uptake coefficients in polluted air in North America. Third, there was a significant contribution of biogenic hydrocarbons to NO3 loss inferred from canister samples taken during daytime. Finally, daytime N2O5 mixing ratios were in accord with their predicted photochemical steady state. Heterogeneous uptake of N2O5 in fog is determined to be an important production mechanism for soluble nitrate, even during daytime. Key Points Large (up to 12 ppbv N2O5) but infrequent nocturnal NOx outflow from the Pearl River Delta Average N2O5 uptake coefficients 0.014 ± 0.007, in line with residual layer measurements in the U.S. Daytime N2O5 follows predicted steady state but rapidly produces soluble nitrate in fog.Department of Civil and Environmental Engineerin

    Dejian Mind-Body Intervention on Depressive Mood of Community-Dwelling Adults: A Randomized Controlled Trial

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    The present study evaluated the effectiveness of a short-term mind-body intervention program on improving the depressive mood of an adult community sample. Forty adult volunteers with various degrees of depressive mood were randomly assigned to the experimental group (Dejian Mind-Body Intervention, DMBI) and control group (Cognitive-Behavioral Therapy, CBT). For each group, a total of four 90-min weekly sessions were conducted. Treatment-related changes were measured using the Beck Depression Inventory (BDI-II), an electroencephalographic indicator of positive affect (i.e., prefrontal activation asymmetry), and self-report ratings on physical health. Results indicated that both the DMBI and the CBT group demonstrated significant reduction in depressive mood. However, among individuals with moderate to severe depressive mood at baseline, only those in the DMBI but not the CBT group showed significant reduction in depressive mood. Besides, only the DMBI group demonstrated a significant increase in prefrontal activation asymmetry, suggesting increase in positive affect. While most psychological therapies for depressive mood normally take several months to show treatment effect, the present findings provided initial data suggesting that the DMBI was effective in improving depressive mood of community adults after 1 month of training

    Observations of nitryl chloride and modeling its source and effect on ozone in the planetary boundary layer of southern China

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    Nitryl chloride (ClNO2) plays potentially important roles in atmospheric chemistry, but its abundance and effect are not fully understood due to the small number of ambient observations of ClNO2 to date. In late autumn 2013, ClNO2 was measured with a chemical ionization mass spectrometer (CIMS) at a mountain top (957 m above sea level) in Hong Kong. During 12 nights with continuous CIMS data, elevated mixing ratios of ClNO2 (>400 parts per trillion by volume) or its precursor N2O5 (>1000 pptv) were observed on six nights, with the highest ever reported ClNO2 (4.7 ppbv, 1 min average) and N2O5 (7.7 ppbv, 1 min average) in one case. Backward particle dispersion calculations driven by winds simulated with a mesoscale meteorological model show that the ClNO2/N2O5-laden air at the high-elevation site was due to transport of urban/industrial pollution north of the site. The highest ClNO2/N2O5 case was observed in a later period of the night and was characterized with extensively processed air and with the presence of nonoceanic chloride. A chemical box model with detailed chlorine chemistry was used to assess the possible impact of the ClNO2 in the well-processed regional plume on next day ozone, as the air mass continued to downwind locations. The results show that the ClNO2 could enhance ozone by 5-16% at the ozone peak or 11-41% daytime ozone production in the following day. This study highlights varying importance of the ClNO2 chemistry in polluted environments and the need to consider this process in photochemical models for prediction of ground-level ozone and haze. Key Points First observation of ClNO2 in the planetary boundary layer of China Combined high-resolution meteorological and measurement-constrained chemical models in data analysis ClNO2 enhances daytime ozone peak by 5-16% in well-processed PRD air.Department of Civil and Environmental Engineerin

    Perceived Quality of Care and Lifestyle Counseling Among Patients With Heart Disease

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    Background: To examine patients' perceived quality of care and reported receipt of information on diet and exercise related to cardiovascular disease prevention. Methods: Patients admitted with acute coronary syndromes or elective cardiac catheterization were eligible for enrollment. Baseline medical information was collected through medical-record review. Patients completed surveys at the time of hospitalization that included items on perceived quality of care and whether they had received information from a healthcare provider on diet and exercise as related to their heart. Perceived quality of care was grouped into 3 categories: (1) poor to fair, (2) good, and (3) very good to excellent. Results: Among the 182 cardiac patients who completed the survey, those who reported poor to fair quality of care were more likely to report that they had received no advice regarding diet as compared with those who perceived their quality of care as good or very good to excellent (61%, 59%, and 26%, respectively, P < 0.0001). A similar pattern was observed for exercise (71%, 74%, and 36%, respectively, P < 0.0001). Conclusions: Patients with low perceived quality of care were less likely to have discussed diet and exercise habits with healthcare providers. Improving receipt of lifestyle counseling is warranted given the central role that diet and exercise play in secondary prevention. Copyright © 2010 Wiley Periodicals, Inc. Dr. Jackson receives support from the National Heart, Lung, and Blood Institute of the National Institutes of Health (K23 HL073310-01). The authors have no other funding, financial relationships, or conflicts of interest to disclose.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78479/1/20839_ftp.pd

    An Introduction to Quantum Order, String-net Condensation, and Emergence of Light and Fermions

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    We review some recent work on new states of matter. Those states cannot be described symmetry breaking and hence contain a new kind of order -- quantum order. Some quantum orders are shown to be closely related to string-net condensations. Those quantum orders lead to an emergence of gauge bosons and fermions from pure bosonic models.Comment: 16 pages. Homepage http://dao.mit.edu/~we

    Rational sequences for the conductance in quantum wires from affine Toda field theories

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    We analyse the expression for the conductance of a quantum wire which is decribed by an integrable quantum field theory. In the high temperature regime we derive a simple formula for the filling fraction. This expression involves only the inverse of a matrix which contains the information of the asymptotic phases of the scattering matrix and the solutions of the constant thermodynamic Bethe ansatz equations. Evaluating these expressions for minimal affine Toda field theory we recover several sequences of rational numbers, which are multiples of the famous Jain sequence for the filling fraction occurring in the context of the fractional quantum Hall effect. For instance we obtain ν=4m/(2m+1)\nu= 4 m/(2m +1) for A4m1A_{4m-1}-minimal affine Toda field theory. The matrices involved have in general non-rational entries and are not part of previous classification schemes based on integral lattices.Comment: 9 pages Latex, version to appear in Journal of Physics

    Patient-Related Diet and Exercise Counseling: Do Providers’ Own Lifestyle Habits Matter?

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    The goal of this research was to evaluate the personal health behaviors of physicians in training and attending physicians in association with patient-related lifestyle counseling. Physicians at a major teaching hospital were surveyed regarding their personal lifestyle behavior, perceived confidence, and frequency of counseling patients regarding lifestyle behaviors. One hundred eighty-three total responses were received. Trainees were more likely to consume fast food and less likely to consume fruits and vegetables than attendings. Attending physicians were more likely to exercise 4 or more days per week and more than 150 minutes per week. Attending physicians were more likely to counsel their patients regarding a healthy diet (70.7% vs 36.3%, P150 minutes per week, being overweight, and reported adequate training in counseling. Only adequate training in counseling was a predictor of strong self-efficacy for counseling in diet. Many physicians lack confidence in their ability to counsel patients regarding lifestyle. Personal behaviors including regular exercise and better training in counseling techniques may improve patient counseling. Prev Cardiol. 2010;13:180–185. © 2010 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79167/1/j.1751-7141.2010.00079.x.pd
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