48 research outputs found
Measurement of e+e- -> pi+pi- cross section with CMD-2 around rho-meson
The cross section of the process e+e- -> pi+pi- has been measured using about
114000 events collected by the CMD-2 detector at the VEPP-2M e+e- collider in
the center-of-mass energy range from 0.61 to 0.96 GeV. Results of the pion form
factor determination with a 0.6% systematic uncertainty are presented.
Implications for the hadronic contribution to the muon anomalous magnetic
moment are discussed.Comment: 17 pages, 4 figures, submitted to PL
The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance
INTRODUCTION
Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic.
RATIONALE
We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs).
RESULTS
Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants.
CONCLUSION
Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century
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Exploring the relationships among food insecurity, alcohol use, and sexual risk taking among men and women living in South African townships
South African townships have among the highest rates of HIV infection in the world. Considerable research on understanding the high rates of HIV transmission in this country has identified alcohol use as a critical factor in driving the HIV epidemic. Although the relationship between alcohol use and sexual risk-taking is well documented, less is known about how other factors, such as food insecurity, might be important in understanding alcohol's role in sexual risk-taking. Furthermore, prior research has highlighted
how patterns of alcohol use and sexual risk-taking tend to vary by gender. We examined how food insecurity is related to both alcohol use and sexual risk-taking. We administered anonymous community surveys to men (n = 1,137) and women (n = 458)
residing within four contiguous Black African townships outside of Cape Town, South Africa. In multivariate linear regression, we found that food insecurity was related to having higher numbers of male sex partners and condom-protected sex acts among
women only. These relationships, however, were fully mediated by women's alcohol use. Among men, we found that food insecurity was negatively related to unprotected sex; that is, men with greater food security reported more unprotected sex acts. Unlike the results found among women, this relationship was not mediated by alcohol use. Food insecurity appears to be an important factor in understanding patterns of sexual risk-taking in regards to gender and alcohol use, and may serve as an important point of intervention for reducing HIV transmission rates.
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Condom negotiation, HIV testing, and HIV risks among women from alcohol serving venues in Cape Town, South Africa
Background: Women in South Africa are at particularly high-risk for HIV infection and are dependent on their male partners'
use of condoms for sexual risk reduction. However, many women are afraid to discuss condoms with male partners, placing
them at higher risk of HIV infection.
Purpose: To examine the association between fear of condom negotiation with HIV testing and transmission risk behaviors,
including alcohol use and sexual risks among South African women.
Method: Women (N = 1333) residing in a primarily Xhosa-speaking African township in Cape Town and attending informal
alcohol-serving venues (shebeens) completed anonymous surveys. Logistic regression was used to test the hypothesis that
fear of condom negotiation would be associated with increased risk for HIV.
Results: Compared to women who did not fear condom negotiation, those who did were significantly less likely to have
been tested for HIV, were more likely to have experienced relationship abuse, and to report more alcohol use and more
unprotected sex.
Conclusions: For women in South Africa, fear of condom negotiation is related to higher risk of HIV. HIV prevention efforts,
including targeted HIV counseling and testing, must directly address gender issues.
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Collective efficacy and HIV prevention in South African townships
South African townships have high HIV prevalence and a strong need for collective action to change normative sexual risk behaviors. This study investigated the relationship between perceptions of individuals about collective efficacy in the community's ability to prevent HIV and their personal HIV risk behaviors. Men (n = 1,581) and women (n = 718) completed anonymous surveys within four Black African Townships in Cape Town, South Africa from June 2008 to December 2010. Measures included demographics, alcohol use, attitudinal and behavioral norms, sexual health communications, and sexual risk behaviors. In multivariate logistic regressions, men were more likely to endorse collective efficacy if they were married, drank less often in alcohol serving establishments, believed that fewer men approve of HIV risk behaviors, talk more with others about HIV/AIDS, and had more sex partners in the past month. Women were more likely to endorse collective efficacy if they drank alcohol less often, talked more with others about HIV/AIDS, had more sex partners in the past month, but reported fewer unprotected sex acts in the past month. Community level interventions that strengthen collective efficacy beliefs will have to consider both protective and risk behaviors associated with believing that the community is ready and capable of preventing HIV.
Stereoelectronic Effects: A Powerful Concept in Explaining Kinetic and Thermodynamic Aspects of Retro Cheletropic Reactions
Learning words: children disregard some pragmatic information that conflicts with mutual exclusivity
Recent insight into the mechanism of proton-induced composite particle emission in inclusive reactions
Low carbohydrate diets and performance
Athletes are continually searching for means to optimize their performance. Within the past 20 years, athletes and scientists have reported and/or observed that consuming a carbohydrate restricted diet may improve performance. The original theories explaining the purported benefits centered on the fact that fat oxidation increases, thereby "sparing" muscle glycogen. More recent concepts that explain the plausibility of the ergogenicity of low carbohydrate, or high fat, diets on exercise performance pertain to an effect similar to altitude training. We and others have observed that, while fat oxidation may be increased, the ability to maintain high intensity exercise (e.g., above the lactate threshold) seems to be compromised or at least indifferent compared to when more carbohydrate was consumed. That said, clinical studies clearly demonstrate that ad-libitum low carbohydrate diets elicit greater decreases in body weight and fat than energy equivalent low fat diets,
especially over a short duration. Thus, while low carbohydrate and high fat diets appear detrimental or indifferent relative to performance, they may be a faster means to achieve a more competitive body composition