Comparative analysis of the effects of tantalum doping and annealing on atomic layer deposited (Ta2O5)(x)(Al2O3)(1-x) as potential gate dielectrics for GaN/AlxGa1-xN/GaN high electron mobility transistors

This paper describes a method to optimally combine wide band gap Al2O3 with high dielectric constant (high-κ) Ta2O5 for gate dielectric applications. (Ta2O5)x(Al2O3)1−x thin films deposited by thermal atomic layer deposition (ALD) on GaN-capped AlxGa1−xN/GaN high electron mobility transistor (HEMT) structures have been studied as a function of the Ta2O5 molar fraction. X-ray photoelectron spectroscopy shows that the bandgap of the oxide films linearly decreases from 6.5 eV for pure Al2O3 to 4.6 eV for pure Ta2O5. The dielectric constant calculated from capacitance-voltage measurements also increases linearly from 7.8 for Al2O3 up to 25.6 for Ta2O5. The effect of post-deposition annealing in N2 at 600 °C on the interfacial properties of undoped Al2O3 and Ta-doped (Ta2O5)0.12(Al2O3)0.88 films grown on GaN-HEMTs has been investigated. These conditions are analogous to the conditions used for source/drain contact formation in gate-first HEMT technology. A reduction of the Ga-O to Ga-N bond ratios at the oxide/HEMT interfaces is observed after annealing, which is attributed to a reduction of interstitial oxygen-related defects. As a result, the conduction band offsets (CBOs) of the Al2O3/GaN-HEMT and (Ta2O5)0.16(Al2O3)0.84/GaN-HEMT samples increased by ∼1.1 eV to 2.8 eV and 2.6 eV, respectively, which is advantageous for n-type HEMTs. The results demonstrate that ALD of Ta-doped Al2O3 can be used to control the properties of the gate dielectric, allowing the κ-value to be increased, while still maintaining a sufficient CBO to the GaN-HEMT structure for low leakage currents. VC 2016 AIP Publishing LL

Predicting resistance as indicator for need to switch from first-line antiretroviral therapy among patients with elevated viral loads: Development of a risk score algorithm

Background: In resource-limited settings, where resistance testing is unavailable, confirmatory testing for patients with high viral loads (VL) delays antiretroviral therapy (ART) switches for persons with resistance. We developed a risk score algorithm to predict need for ART change by identifying resistance among persons with persistently elevated VL. Methods: We analyzed data from a Phase IV open-label trial. Using logistic regression, we identified demographic and clinical characteristics predictive of need for ART change among participants with VLs ≥1000 copies/ml, and assigned model-derived scores to predictors. We designed three models, including only variables accessible in resource-limited settings. Results: Among 290 participants with at least one VL ≥1000 copies/ml, 51 % (148/290) resuppressed and did not have resistance testing; among those who did not resuppress and had resistance testing, 47 % (67/142) did not have resistance and 53 % (75/142) had resistance (ART change needed for 25.9 % (75/290)). Need for ART change was directly associated with higher baseline VL and higher VL at time of elevated measure, and inversely associated with treatment duration. Other predictors included body mass index and adherence. Area under receiver operating characteristic curves ranged from 0.794 to 0.817. At a risk score ≥9, sensitivity was 14.7-28.0 % and specificity was 96.7-98.6 %. Conclusions: Our model performed reasonably well and may be a tool to quickly transition persons in need of ART change to more effective regimens when resistance testing is unavailable. Use of this algorithm may result in public health benefits and health system savings through reduced transmissions of resistant virus and costs on laboratory investigations

Comparison of atomic layer deposited Al2O3 and (Ta2O5)0.12(Al2O3)0.88 gate dielectrics on the characteristics of GaN-capped AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors

The current research investigates the potential advantages of replacing Al2O3 with (Ta2O5)0.12(Al2O3)0.88 as a higher dielectric constant (κ) gate dielectric for GaN-based metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs). The electrical characteristics of GaN-capped AlGaN/GaN MOS-HEMT devices with (Ta2O5)0.12(Al2O3)0.88 as the gate dielectric are compared to devices with Al2O3 gate dielectric and devices without any gate dielectric (Schottky HEMTs). Compared to the Al2O3 MOS-HEMT, the (Ta2O5)0.12(Al2O3)0.88 MOS-HEMT achieves a larger capacitance and a smaller absolute threshold voltage, together with a higher two-dimensional electron gas carrier concentration. This results in a superior improvement of the output characteristics with respect to the Schottky HEMT, with higher maximum and saturation drain current values observed from DC current-voltage measurements. Gate transfer measurements also show a higher transconductance for the (Ta2O5)0.12(Al2O3)0.88 MOS-HEMT. Furthermore, from OFF-state measurements, the (Ta2O5)0.12(Al2O3)0.88 MOS-HEMT shows a larger reduction of the gate leakage current in comparison to the Al2O3 MOS-HEMT. These results demonstrate that the increase in κ of (Ta2O5)0.12(Al2O3)0.88 compared with Al2O3 leads to enhanced device performance when the ternary phase is used as a gate dielectric in the GaN-based MOS-HEMT

Non-Perturbative Superpotentials in F-theory and String Duality

We use open-closed string duality between F-theory on K3xK3 and type II strings on CY manifolds without branes to study non-perturbative superpotentials in generalized flux compactifications. On the F-theory side we obtain the full flux potential including D3-instanton contributions and show that it leads to an explicit and simple realization of the three ingredients of the KKLT model for stringy dS vacua. The D3-instanton contribution is highly non-trivial, can be systematically computed including the determinant factors and demonstrates that a particular flux lifts very effectively zero modes on the instanton. On the closed string side, we propose a generalization of the Gukov-Vafa-Witten superpotential for type II strings on generalized CY manifolds, depending on all moduli multiplets.Comment: 49 pages, harvmac, 1 figure; references & figures adde

Catastrophic health expenditure among industrial workers in a large-scale industry in Nepal, 2017: a cross-sectional study

Objectives The study aimed at estimating out-of-pocket (OOP) expenditure, catastrophic health expenditure (CHE) and distress financing due to hospitalisation and outpatient care among industrial workers in Eastern Nepal. Methods We conducted a cross-sectional study involving industrial workers employed in a large-scale industry in Eastern Nepal. Those who were hospitalised in the last 1 year or availed outpatient care within the last 30 days were administered a structured questionnaire to estimate the cost of illness. CHE was defined as expenditure more than 20% of annual household income. Distress financing was defined as borrowing money/loan or selling assets to cope with OOP expenditure on health. Results Of 1824 workers eligible for the study, 1405 (77%) were screened, of which 85 (6%) were hospitalised last year; 223 (16%) attended outpatient department last month. The median (IQR) OOP expenditure from hospitalisation and outpatient care was US$124 (71–282) and US$36 (19–61), respectively. Among those hospitalised, the prevalence of CHE and distress financing was found to be 13% and 42%, respectively, and due to outpatient care was 0.4% and 42%, respectively. Drugs and diagnostics account for a large share of direct costs in both public and private sectors. More than 80% sought hospitalisation and outpatient care in a private sector. Conclusion Industrial workers face significant financial risks due to ill health compared with the general population. Poor utilisation and higher cost of care in public health facilities warrant strengthening of public sector through increased government spending. The labour act 2014 of Nepal should be strictly adhered

How is Perceived Community Cohesion and Membership in Community Groups Associated with Children’s Dietary Adequacy in Disadvantaged Communities? A Case of the Indian Sundarbans

Background: Membership in community groups and a sense of community cohesion may facilitate collective action in mobilizing resources towards better health outcomes. This paper explores the relationship of these factors, along with individual level socio-economic variables, to dietary adequacy among children below 6 years of age, a proximate determinant of child malnutrition. Methods: We conducted a cross-sectional survey in Patharpratima block of the Sundarbans in West Bengal, India, using a two-stage, 30 cluster random sampling design. In 1200 sampled households, we used a structured questionnaire to interview mothers of children below 6 years of age on their child’s nutritional intake. We also interviewed household heads to assess perceived community cohesion using a nine item scale, membership in any community self-help organization, and other socio-economic determinants. We used a logistic regression model to assess their association with a minimum acceptable diet among children between 6 months to 6 years. Results: Only 9.33 % children between 6 and 71 months of age received a minimum acceptable diet. With each increase in the perceived community cohesion score (scale 0-9), a child is 1.31 times more likely to have minimum acceptable diet (95 % CI 1.14, 1.50). The odds of minimum acceptable diet were also higher among children whose mothers had primary education (2.09, 95 % CI 1.03, 2.94) as compared to illiterate mothers and in households with surplus food resources (2.72, 95 % CI 1.32, 5.58) as compared to those without surplus or deficit. In contrast, registering at an Anganwadi (government early child development) centre (odds ratio 1.34 95 % CI 0.69, 2.60) and community membership (odds ratio 0.93, 95 % CI 0.59, 1.46) were not associated with minimum acceptable diet. Conclusion: The results are consistent with what is known about the importance of maternal education and access to food resources in ensuring that children have a minimum acceptable diet. Perceived community cohesion seems to play a positive role in children’s diets. Further research needs to clarify which community characteristics and services are the most relevant, how they can better support children’s diets, and how interventions can strengthen these community characteristics and services

Unlocking community capabilities for improving maternal and newborn health: participatory action research to improve birth preparedness, health facility access, and newborn care in rural Uganda

Background: Community capacities and resources must be harnessed to complement supply side initiatives addressing high maternal and neonatal mortality rates in Uganda. This paper reflects on gains, challenges and lessons learnt from working with communities to improve maternal and newborn health in rural Uganda. Methods: A participatory action research project was supported from 2012 to 2015 in three eastern districts. This project involved working with households, saving groups, sub county and district leaders, transporters and village health teams in diagnosing causes of maternal and neonatal mortality and morbidity, developing action plans to address these issues, taking action and learning from action in a cyclical manner. This paper draws from project experience and documentation, as well as thematic analysis of 20 interviews with community and district stakeholders and 12 focus group discussions with women who had recently delivered and men whose wives had recently delivered. Results: Women and men reported increased awareness about birth preparedness, improved newborn care practices and more male involvement in maternal and newborn health. However, additional direct communication strategies were required to reach more men beyond the minority who attended community dialogues and home visits. Saving groups and other saving modalities were strengthened, with money saved used to meet transport costs, purchase other items needed for birth and other routine household needs. However saving groups required significant support to improve income generation, management and trust among members. Linkages between savings groups and transport providers improved women’s access to health facilities at reduced cost. Although village health teams were a key resource for providing information, their efforts were constrained by low levels of education, inadequate financial compensation and transportation challenges. Ensuring that the village health teams and savings groups functioned required regular supervision, review meetings and payment for supervisors to visit. Conclusions: This participatory program, which focused on building the capacity of community stakeholders, was able to improve local awareness of maternal and newborn health practices and instigate local action to improve access to healthcare. Collaborative problem solving among diverse stakeholders, continuous support and a participatory approach that allowed flexibility were essential project characteristics that enabled overcoming of challenges faced

Explaining the impact of a women's group led community mobilisation intervention on maternal and newborn health outcomes: the Ekjut trial process evaluation

Background: Few large and rigorous evaluations of participatory interventions systematically describe their context and implementation, or attempt to explain the mechanisms behind their impact. This study reports process evaluation data from the Ekjut cluster-randomised controlled trial of a participatory learning and action cycle with women's groups to improve maternal and newborn health outcomes in Jharkhand and Orissa, eastern India (20052008). The study demonstrated a 45% reduction in neonatal mortality in the last two years of the intervention, largely driven by improvements in safe practices for home deliveries.Methods: A participatory learning and action cycle with 244 women's groups was implemented in 18 intervention clusters covering an estimated population of 114 141. We describe the context, content, and implementation of this intervention, identify potential mechanisms behind its impact, and report challenges experienced in the field. Methods included a review of intervention documents, qualitative structured discussions with group members and non-group members, meeting observations, as well as descriptive statistical analysis of data on meeting attendance, activities, and characteristics of group attendees.Results: Six broad, interrelated factors influenced the intervention's impact: (1) acceptability; (2) a participatory approach to the development of knowledge, skills and 'critical consciousness'; (3) community involvement beyond the groups; (4) a focus on marginalized communities; (5) the active recruitment of newly pregnant women into groups; (6) high population coverage. We hypothesize that these factors were responsible for the increase in safe delivery and care practices that led to the reduction in neonatal mortality demonstrated in the Ekjut trial.Conclusions: Participatory interventions with community groups can influence maternal and child health outcomes if key intervention characteristics are preserved and tailored to local contexts. Scaling-up such interventions requires (1) a detailed understanding of the way in which context affects the acceptability and delivery of the intervention; (2) planned but flexible replication of key content and implementation features; (3) strong support for participatory methods from implementing agencies

Phellinus linteus suppresses growth, angiogenesis and invasive behaviour of breast cancer cells through the inhibition of AKT signalling

The antitumour activity of a medicinal mushroom Phellinus linteus (PL), through the stimulation of immune system or the induction of apoptosis, has been recently described. However, the molecular mechanisms responsible for the inhibition of invasive behaviour of cancer cells remain to be addressed. In the present study, we demonstrate that PL inhibits proliferation (anchorage-dependent growth) as well as colony formation (anchorage-independent growth) of highly invasive human breast cancer cells. The growth inhibition of MDA-MB-231 cells is mediated by the cell cycle arrest at S phase through the upregulation of p27Kip1 expression. Phellinus linteus also suppressed invasive behaviour of MDA-MB-231 cells by the inhibition of cell adhesion, cell migration and cell invasion through the suppression of secretion of urokinase-plasminogen activator from breast cancer cells. In addition, PL markedly inhibited the early event in angiogenesis, capillary morphogenesis of the human aortic endothelial cells, through the downregulation of secretion of vascular endothelial growth factor from MDA-MB-231 cells. These effects are mediated by the inhibition of serine-threonine kinase AKT signalling, because PL suppressed phosphorylation of AKT at Thr308 and Ser473 in breast cancer cells. Taken together, our study suggests potential therapeutic effect of PL against invasive breast cancer

A cluster randomised controlled trial of the community effectiveness of two interventions in rural Malawi to improve health care and to reduce maternal, newborn and infant mortality

<p>Abstract</p> <p>Background</p> <p>The UN Millennium Development Goals call for substantial reductions in maternal and child mortality, to be achieved through reductions in morbidity and mortality during pregnancy, delivery, postpartum and early childhood. The MaiMwana Project aims to test community-based interventions that tackle maternal and child health problems through increasing awareness and local action.</p> <p>Methods/Design</p> <p>This study uses a two-by-two factorial cluster-randomised controlled trial design to test the impact of two interventions. The impact of a community mobilisation intervention run through women's groups, on home care, health care-seeking behaviours and maternal and infant mortality, will be tested. The impact of a volunteer-led infant feeding and care support intervention, on rates of exclusive breastfeeding, uptake of HIV-prevention services and infant mortality, will also be tested. The women's group intervention will employ local female facilitators to guide women's groups through a four-phase cycle of problem identification and prioritisation, strategy identification, implementation and evaluation. Meetings will be held monthly at village level. The infant feeding intervention will select local volunteers to provide advice and support for breastfeeding, birth preparedness, newborn care and immunisation. They will visit pregnant and new mothers in their homes five times during and after pregnancy.</p> <p>The unit of intervention allocation will be clusters of rural villages of 2500-4000 population. 48 clusters have been defined and randomly allocated to either women's groups only, infant feeding support only, both interventions, or no intervention. Study villages are surrounded by 'buffer areas' of non-study villages to reduce contamination between intervention and control areas. Outcome indicators will be measured through a demographic surveillance system. Primary outcomes will be maternal, infant, neonatal and perinatal mortality for the women's group intervention, and exclusive breastfeeding rates and infant mortality for the infant feeding intervention.</p> <p>Structured interviews will be conducted with mothers one-month and six-months after birth to collect detailed quantitative data on care practices and health-care-seeking. Further qualitative, quantitative and economic data will be collected for process and economic evaluations.</p> <p>Trial registration</p> <p>ISRCTN06477126</p