Effect of hydrogen adsorption on the quasiparticle spectra of graphene

We use the non-interacting tight-binding model to study the effect of isolated hydrogen adsorbates on the quasiparticle spectra of single-layer graphene. Using the Green's function approach, we obtain analytic expressions for the local density of states and the spectral function of hydrogen-doped graphene, which are also numerically evaluated and plotted. Our results are relevant for the interpretation of scanning tunneling microscopy and angle-resolved photoemission spectroscopy data of functionalized graphene.Comment: 4 pages, 3 figures, minor corrections to tex

Surgical treatment versus medical treatment in hypertrophic obstructive cardiomyopathy

Sixty-three patients operated upon for HOCM and 49 patients selected for non-surgical treatment have been followed-up for 15 years. Pre-operatively, surgical patients had a higher left ventricular outflow tract gradient at rest and, on the average, more severe symptoms than non-surgical patients. Septal myectomy relieved the pressure gradient and symptoms more consistently than long-term treatment with β-blockers or verapamil. Within an average observation time of 7½ years, there was late deterioration or death in almost half of the non-surgical patients but in less than one-quarter in the operated patients. The 10 year mortality rate was 80% in the surgical series and 71% in the non-surgical series. In operated patients, pre-operative symptomatic status was significantly related to early and late mortality. In medically treated patients, mortality was unrelated to symptoms; however, it was significantly lower in patients receiving long term treatment with β-blockers or verapamil. In conclusion, a high basal pressure gradient associated to limiting symptoms is a clear-cut indication for surgery. Other indications are more debatable. In medically treated patients, long-term administration of β-blockers or verapamil is beneficial even without symptoms as it appears to improve prognosi

Interventions addressing the adolescent HIV continuum of care in South Africa: a systematic review and modified Delphi analysis

INTRODUCTION: Compared with adults, adolescents in South Africa have larger gaps at each step of the HIV continuum of care resulting in low levels of viral suppression. METHODS: We conducted a systematic review and modified Delphi analysis of interventions addressing the HIV continuum of care for adolescents in South Africa. We searched PubMed, Science Direct, and Google Scholar and online conference proceedings from the International AIDS Society, the International AIDS Conference, and the Conference on Retrovirology and Opportunistic Infections from 1 January 2010 to 30 September 2020. We then conducted a modified Delphi analysis with 29 researchers involved in the National Institutes of Health's Fogarty International-supported Adolescent HIV Implementation Science Alliance-South Africa to evaluate interventions for efficacy, feasibility and potential for scale-up. RESULTS: We identified nine initial published articles containing interventions addressing the adolescent HIV continuum of care in South Africa, including five interventions focused on HIV diagnosis, two on antiretroviral therapy adherence and two on retention in care. No studies addressed linkage to care or transition from paediatric to adult care. Two studies discussed intervention costs. In-home and HIV self-testing, community-based adherence support, and provision of adolescent-friendly services were the most impactful and scalable interventions addressing the adolescent HIV continuum of care. CONCLUSION: Future interventions should work comprehensively across the adolescent HIV continuum of care and be tailored to the specific needs of adolescents

Stillbirth rate by maternal HIV serostatus and antiretroviral use in pregnancy in South Africa: An audit

No abstract

Sequential group trial to determine gastrointestinal site of absorption and systemic exposure of azathioprine

Azathioprine (AZA) is used in the treatment of patients with refractory inflammatory bowel disease; however, its use is limited because of systemic toxicity associated with long-term use. Ileocecal delivery of AZA might be advantageous if local intestinal therapeutic effects could be provided with decreased systemic side effects. Decreased cecal systemic absorption would allow higher dosages of AZA to be administered. A two-phase study was performed to compare the systemic exposure of AZA and 6-mercaptopurine (6-MP) following administration of AZA into the stomach, jejunum, and cecum and to compare the systemic exposure to AZA and 6-MP following administration of three different dosages of AZA into the cecum. In phase I, six healthy male volunteers received three 50 mg sequential doses of AZA via an oral tube directly placed into the stomach, jejunum, and cecum, respectively. In phase II, six healthy male volunteers received three different dosages (50, 300, 600 mg of AZA) into the cecum. Plasma concentrations of AZA and 6-MP at various times were quantified and area under the plasma concentration-time curve (AUC) and mean residence time (MRT) were determined. No significant differences in the AUC of AZA were seen at the different sites. The AUC of 6-MP following administration of AZA into the jejunum (67.0 ± 30.1 ng × hr/ml) was higher compared to the stomach (39.9 ± 38.1 ng/hr/ml) and cecum (29.2 ± 10.9 ng × hr/ml). Jejunal absorption was 68% higher than absorption from the stomach and 129% higher than that of the cecum. Gastric absorption was 27% higher than that of the cecum. Increased dosages given into the cecum resulted in increased AUCs of AZA and 6-MP. The AUCs of AZA following 50, 300, and 600 mg dosages were 16.9 ± 7.4, 52.3 ± 67.2, and 132 ± 151 ng × hr/ml, respectively, and the AUCs of 6-MP were 22.2 ± 14.9, 63.4 ± 50.6, and 104 ± 115 ng × hr/ml, respectively. Systemic exposure to 6-MP is reduced following administration of AZA into the cecum, most likely secondary to reduced absorption of 6-MP from the colon. Higher dosages of AZA presented to the cecum do result in increased systemic absorption, but may still allow more drug to be administered with less toxicity than the same dose received orally

Who will use pre-exposure prophylaxis (PrEP) and why?: Understanding PrEP awareness and acceptability amongst men who have sex with men in the UK – a mixed methods study

Background: Recent clinical trials suggest that pre-exposure prophylaxis (PrEP) may reduce HIV transmission by up to 86% for men who have sex with men (MSM), whilst relatively high levels of PrEP acceptability have been reported to date. This study examines PrEP awareness amongst sub-groups of MSM communities and acceptability amongst MSM in a low prevalence region (Scotland, UK), using a mixed methods design. Methods: Quantitative surveys of n = 690 MSM recruited online via social and sociosexual media were analysed using descriptive statistics and multivariate logistic regression. In addition, n = 10 in-depth qualitative interviews with MSM were analysed thematically. Results: Under one third (29.7%) of MSM had heard of PrEP, with awareness related to living in large cities, degree level education, commercial gay scene use and reporting an HIV test in the last year. Just under half of participants (47.8%) were likely to use PrEP if it were available but there was no relationship between PrEP acceptability and previous PrEP awareness. Younger men (18–25 years) and those who report higher risk UAI were significantly more likely to say they would use PrEP. Qualitative data described specific PrEP scenarios, illustrating how risk, patterns of sexual practice and social relationships could affect motivation for and nature of PrEP use. Conclusion: These findings suggest substantial interest PrEP amongst MSM reporting HIV risk behaviours in Scotland. Given the Proud results, there is a strong case to investigate PrEP implementation within the UK. However, it appears that disparities in awareness have already emerged along traditional indicators of inequality. Our research identifies the need for comprehensive support when PrEP is introduced, including a key online component, to ensure equity of awareness across diverse MSM communities (e.g. by geography, education, gay scene use and HIV proximity), as well as to responding to the diverse informational and sexual health needs of all MSM communities

Enhanced ozone strongly reduces carbon sink strength of adult beech (Fagus sylvatica) – Resume from the free-air fumigation study at Kranzberg Forest

Ground-level ozone (O3) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O3-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O3 exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O3 levels. Elevated O3 significantly weakened the C sink strength of the tree–soil system as evidenced by lowered photosynthesis and 44% reduction in whole-stem growth, but increased soil respiration. Associated effects in leaves and roots at the gene, cell and organ level varied from year to year, with drought being a crucial determinant of O3 responsiveness. Regarding adult individuals of a late-successional tree species, empirical proof is provided first time in relation to recent modelling predictions that enhanced ground-level O3 can substantially mitigate the C sequestration of forests in view of climate change