Production of Secondary Organic Aerosol During Aging of Biomass Burning Smoke From Fresh Fuels and Its Relationship to VOC Precursors

After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog-chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high-resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low-volatility POA as a reference standard (akin to a naturally occurring internal standard). These smoke aging experiments revealed variable organic aerosol (OA) enhancements, even for smoke from similar fuels and aging mechanisms. This variable OA enhancement correlated well with measured differences in the amounts of emitted volatile organic compounds (VOCs) that could subsequently be oxidized to form SOA. For some aging experiments, we were able to predict the SOA production to within a factor of 2 using a fuel-specific VOC emission inventory that was scaled by burn-specific toluene measurements. For fires of coniferous fuels that were dominated by needle burning, volatile biogenic compounds were the dominant precursor class. For wiregrass fires, furans were the dominant SOA precursors. We used a POA tracer ion to calculate the amount of mass lost due to gas-phase oxidation and subsequent volatilization of semivolatile POA. Less than 5% of the POA mass was lost via multiphase oxidation-driven evaporation during up to 2 hr of equivalent atmospheric oxidation

Fluorescent Excitation of Spectral Lines in Planetary Nebulae

Fluorescent excitation of spectral lines is demonstrated as a function of temperature-luminosity and the distance of the emitting region from the central stars of planetary nebulae. The electron densities and temperatures are determined, and the method is exemplified through a detailed analysis of spectral observations of a high excitation PN, NGC 6741, observed by Hyung and Aller(1997). Fluorescence should also be important in the determination of element abundances. It is suggested that the method could be generally applied to determine or constrain the luminosity and the region of spectral emission in other intensively radiative sources such as novae, supernovae, and active galactic nuclei.Comment: 5 pages, 4 figures (fig.4 in color), ApJ (in press

Visualization at Supercomputing Centers: The Tale of Little Big Iron and the Three Skinny Guys

Supercomputing Centers (SC's) are unique resources that aim to enable scientific knowledge discovery through the use of large computational resources, the Big Iron. Design, acquisition, installation, and management of the Big Iron are activities that are carefully planned and monitored. Since these Big Iron systems produce a tsunami of data, it is natural to co-locate visualization and analysis infrastructure as part of the same facility. This infrastructure consists of hardware (Little Iron) and staff (Skinny Guys). Our collective experience suggests that design, acquisition, installation, and management of the Little Iron and Skinny Guys does not receive the same level of treatment as that of the Big Iron. The main focus of this article is to explore different aspects of planning, designing, fielding, and maintaining the visualization and analysis infrastructure at supercomputing centers. Some of the questions we explore in this article include:"How should the Little Iron be sized to adequately support visualization and analysis of data coming off the Big Iron?" What sort of capabilities does it need to have?" Related questions concern the size of visualization support staff:"How big should a visualization program be (number of persons) and what should the staff do?" and"How much of the visualization should be provided as a support service, and how much should applications scientists be expected to do on their own?&quot

Study protocol: the effects of work-site exercise on the physical fitness and work-ability of older workers

BACKGROUND: Older workers have a higher rate and cost of injury than younger workers and with a rapidly ageing work force there is a need to identify strategies to address this problem. Older workers are less physically active and fit than younger workers and so have reduced work ability. The reduced work ability means they are more likely to be fatigued at work and so at greater risk of injury. Exercise could potentially assist this problem. Exercise training has been previously shown to improve fitness in older people however there has been no evaluation of workplace exercise program for older workers. We do not know if the programs are feasible and can improve the fitness and work ability of older workers. We have designed a randomised controlled trial to evaluate whether exercise improves fitness and perceived work-ability of older workers. METHODS/DESIGN: This paper describes the protocol for a trial examining the effects of a 12-week physical training program in workers over the age of 45. Participants will be randomized to an exercise or no-intervention control group. The primary outcomes are cardiorespiratory endurance, lifting capacity, upper and lower limb strength and perceived work-ability. DISCUSSION: This trial will test the feasibility of implementing a worksite-based exercise program as a means of improving the physical fitness and work-ability of older workers performing physically demanding work. If we demonstrate the feasibility of the program we will conduct a larger trial that additionally measures injury outcomes

Barriers encountered during enrollment in an internet-mediated randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Online technology is a promising resource for conducting clinical research. While the internet may improve a study's reach, as well as the efficiency of data collection, it may also introduce a number of challenges for participants and investigators. The objective of this research was to determine the challenges that potential participants faced during the enrollment phase of a randomized controlled intervention trial of Stepping Up to Health, an internet-mediated walking program that utilized a multi-step online enrollment process.</p> <p>Methods</p> <p>We conducted a quantitative content analysis of 623 help tickets logged in a participant management database during the enrollment phase of a clinical trial investigating the effect of an automated internet-mediated walking intervention. Qualitative coding was performed by two trained coders, and 10% of the sample was coded by both coders to determine inter-coder reliability. Quantitative analyses included standard descriptive statistics on ticket characteristics and theme frequency, and a Poisson regression analysis identified characteristics of potential participants who reported more frequent problems during enrollment.</p> <p>Results</p> <p>In total, 880 potential participants visited the study website and 80% completed the enrollment screening. Of the potential participants who visited the study website, 38% had help tickets logged in the participant management database. The total number of help tickets associated with individual potential participants ranged from 0 to 7 (M = .71). Overall, 46% of help tickets were initiated by email and 54% were initiated by phone. The most common help ticket theme was issues related to the study process (48%). The next most prominent theme was discussion related to obtaining medical clearance (34%), followed by issues related to pedometers and uploading (31%). Older individuals, women, and those with lower self-rated internet ability were more likely to report problems during the enrollment process.</p> <p>Conclusion</p> <p>Prospective participants in an online clinical trial encountered a number of barriers to enrollment that led them to request help from study staff. Questions about the complex enrollment process itself were common. In a complex multi-step enrollment process, providing personalized feedback to potential participants indicating their status within the enrollment process may be beneficial.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NCT00729040</p

Large Extra Dimensions and Decaying KK Recurrences

We suggest the possibility that in ADD type brane-world scenarios, the higher KK excitations of the graviton may decay to lower ones owing to a breakdown of the conservation of extra dimensional ``momenta'' and study its implications for astrophysics and cosmology. We give an explicit realization of this idea with a bulk scalar field $\Phi$, whose nonzero KK modes acquire vacuum expectation values. This scenario helps to avoid constraints on large extra dimensions that come from gamma ray flux bounds in the direction of nearby supernovae as well as those coming from diffuse cosmological gamma ray background. It also relaxes the very stringent limits on reheat temperature of the universe in ADD models.Comment: 16 pages, late

Television Watching and Mental Health in the General Population of New York City After September 11

The September 11, 2001 terrorist attacks were watched on television by millions. Using data from a telephone survey of New York City residents in January 2002 (N = 2001), we examined the relations between television watching and probable posttraumatic stress disorder (PTSD) after the attacks. Among those who were directly affected by the attacks or had prior traumatic experiences, watching television was associated with probable PTSD. Experiencing a peri-event panic reaction accounted for some of the association between television watching and probable PTSD. Future research directions are suggested for better understanding the mechanisms behind observed associations between television watching and PTSD.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40284/2/Ahern_Television Watching and Mental Health in_2005.pd

Production of Secondary Organic Aerosol During Aging of Biomass Burning Smoke From Fresh Fuels and Its Relationship to VOC Precursors

After smoke from burning biomass is emitted into the atmosphere, chemical and physical processes change the composition and amount of organic aerosol present in the aged, diluted plume. During the fourth Fire Lab at Missoula Experiment, we performed smog-chamber experiments to investigate formation of secondary organic aerosol (SOA) and multiphase oxidation of primary organic aerosol (POA). We simulated atmospheric aging of diluted smoke from a variety of biomass fuels while measuring particle composition using high-resolution aerosol mass spectrometry. We quantified SOA formation using a tracer ion for low-volatility POA as a reference standard (akin to a naturally occurring internal standard). These smoke aging experiments revealed variable organic aerosol (OA) enhancements, even for smoke from similar fuels and aging mechanisms. This variable OA enhancement correlated well with measured differences in the amounts of emitted volatile organic compounds (VOCs) that could subsequently be oxidized to form SOA. For some aging experiments, we were able to predict the SOA production to within a factor of 2 using a fuel-specific VOC emission inventory that was scaled by burn-specific toluene measurements. For fires of coniferous fuels that were dominated by needle burning, volatile biogenic compounds were the dominant precursor class. For wiregrass fires, furans were the dominant SOA precursors. We used a POA tracer ion to calculate the amount of mass lost due to gas-phase oxidation and subsequent volatilization of semivolatile POA. Less than 5% of the POA mass was lost via multiphase oxidation-driven evaporation during up to 2 hr of equivalent atmospheric oxidation

Modeling Combination Interventions to Prevent Human Immunodeficiency Virus in Adolescent Girls and Young Women in South Africa (HIV Prevention Trials Network 068)

Background: Combination interventions may be an effective way to prevent human immunodeficiency virus (HIV) in adolescent girls and young women. However, current studies are not designed to understand which specific interventions and combinations will be most effective. We estimate the possible impacts of interventions on a combination of factors associated with HIV. Methods: We used the g-formula to model interventions on combinations of HIV risk factors to identify those that would prevent the most incident HIV infections, including low school attendance, intimate partner violence, depression, transactional sex, and age-disparate partnerships. We used data from the HIV Prevention Trials Network (HPTN) 068 study in rural South Africa from 2011 to 2017. We estimated HIV incidence under a potential intervention that reduced each risk factor and compared this to HIV incidence under the current distribution of these risk factors. Results: Although many factors had strong associations with HIV, potential intervention estimates did not always suggest large reductions in HIV incidence because the prevalence of risk factors was low. When modeling combination effects, an intervention to increase schooling, decrease depression, and decease transactional sex showed the largest reduction in incident infection (risk difference,-1.4%; 95% confidence interval [CI],-2.7% to-.2%), but an intervention on only transactional sex and depression still reduced HIV incidence by-1.3% (95% CI,-2.6% to-.2%). Conclusions: To achieve the largest reductions in HIV, both prevalence of the risk factor and strength of association with HIV must be considered. Additionally, intervening on more risk factors may not necessarily result in larger reductions in HIV incidence