Quasi-freestanding and single-atom thick layer of hexagonal boron nitride as a substrate for graphene synthesis

We demonstrate that freeing a single-atom thick layer of hexagonal boron nitride (hbn) from tight chemical bonding to a Ni(111) thin film grown on a W(110) substrate can be achieved by intercalation of Au atoms into the interface. This process has been systematically investigated using angle-resolved photoemission spectroscopy, X-ray photoemission and absorption techniques. It has been demonstrated that the transition of the hbn layer from the "rigid" into the "quasi-freestanding" state is accompanied by a change of its lattice constant. Using chemical vapor deposition, graphene has been successfully synthesized on the insulating, quasi-freestanding hbn monolayer. We anticipate that the in situ synthesized weakly interacting graphene/hbn double layered system could be further developed for technological applications and may provide perspectives for further inquiry into the unusual electronic properties of graphene.Comment: in print in Phys. Rev.

Helium-3 and Helium-4 acceleration by high power laser pulses for hadron therapy

The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (Magnetic Vortex Acceleration and hole-boring Radiation Pressure Acceleration) of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He3 ions, having almost the same penetration depth as He4 with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.Comment: 8 pages, 3 figures, 1 tabl

Lay Perceptions about Tuberculosis among Non-UK-Born African in the United Kingdom

Background: Tuberculosis among non-UK-born Black Africans has been gradually recognized as a public health problem in the UK despite the various interventions implemented. Objectives: To explore the perceptions of non-UK-born Black Africans about TB health risk; to explore the health seeking behavior of the non-UK-born Black Africans in relation to TB and to explore lay views on TB health education and screening as opportunities for health promotion. Methodology and Study Design: A qualitative methodology was used on a purposively selected sample of 12 non-UK-born Black Africans living in Leeds. Face-to-face interviews were conducted to explore the lay perceptions about TB. Thematic analysis was used to derive important themes in accordance to the study objectives. Ethical approval was provided by Leeds Metropolitan University. Setting: Community setting of non-UK-born Black Africans in Leeds, UK. Results: This population holds mixed views and perceptions about tuberculosis, few facilitators and many barriers existed to current TB prevention efforts. The barriers included: language barriers, barriers related to services and systems, immigration status and stigma despite the benefits involved. The potential for black African communities to readily increase the likelihood of behavior change was found as an important finding for this study. Conclusions: Tuberculosis is a preventable public health problem. Involvement of the non-UK-born black Africans communities in the TB prevention may be beneficial for reducing and tackling TB rates in this population. Such an approach is potentially inexpensive and more readily implementable than other suggested strategies such as changes to immigration policies

High Acceptability for Cell Phone Text Messages to Improve Communication of Laboratory Results with HIV-infected Patients in Rural Uganda: A Cross-sectional Survey Study

Background: Patient-provider communication is a major challenge in resource-limited settings with large catchment areas. Though mobile phone usership increased 20-fold in Africa over the past decade, little is known about acceptability of, perceptions about disclosure and confidentiality, and preferences for cell phone communication of health information in the region. Methods: We performed structured interviews of fifty patients at the Immune Suppression Syndrome clinic in Mbarara, Uganda to assess four domains of health-related communication: a) cell phone use practices and literacy, b) preferences for laboratory results communication, c) privacy and confidentiality, and d) acceptability of and preferences for text messaging to notify patients of abnormal test results. Results: Participants had a median of 38 years, were 56% female, and were residents of a large catchment area throughout southwestern Uganda. All participants expressed interest in a service to receive information about laboratory results by cell phone text message, stating benefits of increased awareness of their health and decreased transportation costs. Ninety percent reported that they would not be concerned for unintended disclosure. A minority additionally expressed concerns about difficulty interpreting messages, discouragement upon learning bad news, and technical issues. Though all respondents expressed interest in password protection of messages, there was also a strong desire for direct messages to limit misinterpretation of information. Conclusions: Cell phone text messaging for communication of abnormal laboratory results is highly acceptable in this cohort of HIV-infected patients in rural Uganda. The feasibility of text messaging, including an optimal balance between privacy and comprehension, should be further studied. A supplemental file containing the cell phone survey used in this research is attached below. Note: At the time of writing, David Bangsberg was affiliated with Massachusetts General Hospital, Harvard Medical School, Mbarara University of Science and Technology, and Ragon Institute

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

No abstract

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