Type Ia Supernova Explosion Models

Because calibrated light curves of Type Ia supernovae have become a major tool to determine the local expansion rate of the Universe and also its geometrical structure, considerable attention has been given to models of these events over the past couple of years. There are good reasons to believe that perhaps most Type Ia supernovae are the explosions of white dwarfs that have approached the Chandrasekhar mass, M_ch ~ 1.39 M_sun, and are disrupted by thermonuclear fusion of carbon and oxygen. However, the mechanism whereby such accreting carbon-oxygen white dwarfs explode continues to be uncertain. Recent progress in modeling Type Ia supernovae as well as several of the still open questions are addressed in this review. Although the main emphasis will be on studies of the explosion mechanism itself and on the related physical processes, including the physics of turbulent nuclear combustion in degenerate stars, we also discuss observational constraints.Comment: 38 pages, 4 figures, Annual Review of Astronomy and Astrophysics, in pres

Medical Pluralism Predicts Non-ART Use among Parents in Need of ART: A Community Survey in KwaZulu-Natal, South Africa

Despite documented common use of traditional healers and efforts to scale up antiretroviral treatment (ART) in sub-Saharan Africa, evidence on whether medical pluralism predicts ART use is inconclusive and restricted to clinic settings. This study quantitatively assesses whether medical pluralism predicts ART use among parents in need of ART in South Africa. 2,477 parents or primary caregivers of children were interviewed in HIV-endemic communities of KwaZulu-Natal. Analysis used multiple logistic regression on a subsample of 435 respondents in need of ART, who reported either medical pluralism (24.6 %) or exclusive public healthcare use (75.4 %). Of 435 parents needing ART, 60.7 % reported ART use. Medical pluralism emerged as a persistent negative predictor of ART utilization among those needing it (AOR [95 % CI] = .556 [.344 - .899], p = .017). Use of traditional healthcare services by those who need ART may act as a barrier to treatment access. Effective intersectoral collaboration at community level is urgently needed

Lifestyle Modifications and Policy Implications for Primary and Secondary Cancer Prevention: Diet, Exercise, Sun Safety, and Alcohol Reduction

Improved cancer treatments and cancer detection methods are not likely to completely eradicate the burden of cancer. Primary prevention of cancer is a logical strategy to use to control cancer while also seeking novel treatments and earlier detection. Lifestyle modification strategies to improve primary prevention and risk reduction for the development of cancer include choosing a healthy diet with an emphasis on plant sources, maintaining a healthy weight throughout life, being physically active, regularly using sunscreen and wearing protective clothing, limiting sun exposure during the hours of 10 AM to 2 PM, avoiding indoor tanning, and reducing or eliminating alcohol use. In addition to continued use of ongoing education of the public, health care providers, and cancer support communities, other policy and public health efforts should be pursued as well. Examples of supported and successful policy approaches are included in this article, including efforts to limit indoor tanning and improve community-wide interventions to reduce ultraviolet radiation exposure as well as to formally support various alcohol policy strategies including increasing alcohol taxes, reducing alcohol outlet density, improving clinical screening for alcohol use disorders, and limiting youth exposure to alcohol marketing and advertising. These prevention strategies are expected to have the largest impact on the development of melanoma as well as breast, colorectal, head and neck, liver, and esophageal cancers. The impact of these strategies as secondary prevention is less well understood. Areas of additional needed research and implementation are also highlighted. Future areas of needed research are the effects of these modifications after the diagnosis of cancer (as secondary prevention)