Computing wildfire behaviour metrics from CFD simulation data

In this article, we demonstrate a new post-processing methodology which can be used to analyse CFD wildfire simulation outputs in a model-independent manner. CFD models produce a great deal of quantitative output but require additional post-processing to calculate commonly used wildfire behaviour metrics. Such post-processing has so far been model specific. Our method takes advantage of the 3D renderings that are a common output from such models and provides a means of calculating important fire metrics such as rate of spread and flame height using image processing techniques. This approach can be applied similarly to different models and to real world fire behaviour datasets, thus providing a new framework for model validation. Furthermore, obtained information is not limited to average values over the complete domain but spatially and temporally explicit metric distributions are provided. This feature supports posterior statistical analyses, ultimately contributing to more detailed and rigorous fire behaviour studies.Peer ReviewedPostprint (published version

Collaborative Metaphor Analysis Research Methodology: A Retrospective Self-Study

The purpose of this manuscript is to explicate the metaphor analysis process we employed in a recent study to make this methodology more accessible to future researchers. To explain and demystify metaphor analysis as a method, we describe in detail the three rounds of data analysis leading to findings. We seek to make transparent the messiness and thoughtfulness of the refining process as well as the methodological rigor and trustworthiness. In the discussion that follows, researchers share experiences with and resulting insights into the methodology in hopes of providing future researchers with support for their own metaphor analysis work

How different are men who do not know their HIV status from those who do? Results from an U.S. online study of gay and bisexual men

We compared self-described HIV-positive (31.6%, n=445), HIV-negative (56.8%, n=801), and HIV-unknown (11.6%, n=164) gay and bisexual men (GBM) on sociodemographic and behavioral characteristics. Participants from across the U.S. were enrolled via a popular sexual networking website to complete an online survey. In total, 44.8% of HIV-negative and HIV-unknown men said they had not been tested for HIV in the CDC-recommended last 6 months. HIV-unknown men significantly differed from HIV-negative and HIV-positive men in sexual behavior and HIV status disclosure patterns. HIV-unknown men were more willing than HIV-negative men to take PrEP; however, HIV-unknown men were significantly less likely than others to have health insurance or a primary care provider. Given the observed differences, researchers should consider analyzing men who are HIV-unknown distinctly from HIV-negative and HIV-positive men

Fast Risetime Reverse Bias Pulse Failures in SiC PN Junction Diodes

SiC-based high temperature power devices are being developed for aerospace systems which will require high reliability. One behavior crucial to power device reliability. To date, it has necessarily been assumed to date is that the breakdown behavior of SiC pn junctions will be similar to highly reliable silicon-based pn junctions. Challenging this assumption, we report the observation of anomalous unreliable reverse breakdown behavior in moderately doped (2-3 x 10(exp 17) cm(exp -3)) small-area 4H- and 6H-SiC pn junction diodes at temperatures ranging from 298 K (25 C) to 873 K (600 C). We propose a mechanism in which carrier emission from un-ionized dopants and deep level defects leads to this unstable behavior. The fundamental instability mechanism is applicable to all wide bandgap semiconductors whose dopants are significantly un-ionized at typical device operating temperatures

Familiarity with and preferences for oral and long-acting injectable HIV pre-exposure prophylaxis (PrEP) in a national sample of gay and bisexual men in the U.S.

Objectives: We sought to determine preferences for oral versus long-acting injectable (LAI) PrEP among gay and bisexual men (GBM). Methods: We surveyed a national U.S. sample of 1,071 GBM about forms of PrEP. Results: Overall, 46.0% preferred LAI, 14.3% oral, 21.7% whichever was most effective, 10.1% had no preference, and 7.8% would not take PrEP. There were no differences in PrEP preferences by race/ethnicity, income, region of residence, or relationship status. Those unwilling to take PrEP were significantly older than those who preferred LAI PrEP and those who would take either. Those who preferred the most effective form were younger, had less education, and reported more recent club drug use. Those who reported condomless anal sex and those who thought they were good PrEP candidates were more willing to take PrEP. Long-term health and side effects were of the greatest concern for both LAI and oral PrEP. Conclusions: The availability of LAI PrEP has the potential to increase uptake among GBM. The results of ongoing clinical trials of LAI PrEP will need to demonstrate similar or greater efficacy as daily Truvada for uptake to be maximized

Social Media Use and HIV Transmission Risk Behavior Among Ethnically Diverse HIV-Positive Gay Men: Results of an Online Study in Three U.S. States

Though Black and Hispanic men who have sex with men (MSM) are at an increased risk for HIV, few HIV risk reduction interventions that target HIV-positive MSM, and even fewer that use technology, have been designed to target these groups. Despite similar rates of social media and technology use across racial/ethnic groups, online engagement of minority MSM for HIV prevention efforts is low. Since minority MSM tend to have less representation in online HIV prevention studies, the goals of this online anonymous study of HIV-positive gay-identified men were to test the feasibility of conducting targeted recruitment by race/ethnicity and sexual orientation, to assess technology and social media use,and to assess global HIV transmission risk. In 2011,an anonymous online survey was conducted among 463 members of an HIV-positive personals website. Emails were sent to a subset of HIV-positive male members who self- identified as gay. While 57% were White, substantial proportions of participants were Black (20%) or Hispanic (18 %). Median age was 46 (range 18–79). Men who reported using 3 or more websites or apps to meet sex partners were significantly more likely to report anal intercourse (AOR 4.43, p\.001) and condomless anal sex (CAS) (AOR 2.70, p\.05) in the past 3 months. The only predictor of CAS with HIV-negative or unknown status partners was being under age 30 (AOR3.38, p\ .01). This study helped to inform online targeted recruitment techniques, access to technology and social media use, and sexual risk among a diverse sample of HIV-positive gay men. Efficacy trials of technology-based HIV prevention interventions targeting high-risk minority HIV-positive MSM are warranted

Sexual behavior varies between same-race and different-race partnerships: A daily diary study of highly sexually active Black, Latino, and White gay and bisexual men

Background. Gay and bisexual men (GBM) are at elevated risk for gonorrhea and chlamydia trachomatis (GC/CT). Rectal GC/CT symptoms may be less obvious than urethral, increasing opportunities for undiagnosed rectal GC/CT. Method. A U.S. national sample of 1,071 GBM completed urethral and rectal GC/CT testing and an online survey. Results. In total, 6.2% were GC/CT positive (5.3% rectal, 1.7% urethral). We calculated adjusted (for education, race, age, relationship status, having health insurance, and income) odds ratios for factors associated with rectal and urethral GC/CT diagnoses. Age was inversely associated with urethral and rectal GC/CT. Compared to White men, Latinos had significantly greater odds of rectal GC/CT. Among men who reported anal sex, those reporting only insertive sex had lower odds of rectal GC/CT than men who reported both insertive and receptive. There was a positive association between rectal GC/CT and number of male partners (\u3c12 \u3emonths), the number of anal receptive acts, receptive condomless anal sex (CAS) acts, and insertive CAS acts. Compared to those who had engaged in both insertive and receptive anal sex, those who engaged in only receptive anal sex had lower odds of urethral GC/CT. The number of male partners (\u3c12 \u3emonths) was associated with increased odds of urethral GC/CT. Conclusion. Rectal GC/CT was more common than urethral and associated with some demographic and behavioral characteristics. Our finding that insertive CAS acts was associated with rectal GC/CT highlights that providers should screen patients for GC/CT via a full range of transmission routes, lest GC/CT go undiagnosed