Huge excitonic effects in layered hexagonal boron nitride

The calculated quasiparticle band structure of bulk hexagonal boron nitride using the all-electron GW approximation shows that this compound is an indirect-band-gap semiconductor. The solution of the Bethe-Salpeter equation for the electron-hole two-particle Green function has been used to compute its optical spectra and the results are found in excellent agreement with available experimental data. A detailed analysis is made for the excitonic structures within the band gap and found that the excitons belong to the Frenkel class and are tightly confined within the layers. The calculated exciton binding energy is much larger than that obtained by Watanabe {\it et al} using a Wannier model to interpret their experimental results and assuming that h-BN is a direct-band-gap semiconductor.Comment: 4 pages, 3 figure

Assessment of Knowledge and Consumption Patterns of Soybean, Moringa Oleifera, Aloe Vera and Other Agro-Resources: The Case of the Elderly and Pregnant/Nursing Women in Lome, Togo

Purpose: To assess how soybean products and other agro-resources are known and consumed by some vulnerable populations in Lome (Togo). Methods: A cross sectional study was conducted from March to April 2015 among people aged 50 years and over attending two Pension Fund departments and pregnant and nursing women attending Bè Hospital in Lome. Data were collected using a pre-tested face-to-face questionnaire. Participants were surveyed about their knowledge and consumption habits of soybean, Moringa oleifera, Aloe vera products and other agro-resources. Results: A total of 847 respondents were included in the study with 426 pregnant/nursing women and 421 people aged 50 years and over. The majority of respondents were married (39.5%) and 45.3% of the elderly people were widowed. At least nine over ten respondents (96%) knew soybean products and 76.8% of them reported a lifetime consumption of soybean products. The available and most consumed agro-resources included tofu (82.7%), moringa leaves (87.2%) and soy flour (29.7%). The least consumed products were soymilk, soy yogurt and moringa juice. Respondents also reported using moringa tea and soap, as well as Aloe vera juice and toothpaste. Conclusion: Soybean products and other agricultural resources are well known and consumed by people living in Lome. Data on actual food intake is useful to public health professionals and food safety risk assessors. It is important to inform the public at large of the recognized benefits of some foods that will provide solutions to their health problems

Epidemio-clinical study of the first iterative cesarean in the gynecology-obstetric service at the teaching hospital of Cocody

Background: The iterative caesarean section, is a caesarean section that is performed on a uterus already healed, therefore for fear of maternal and perinatal risks, is recognized as one of the main causes of the inflation of caesarean section in the world. One in three caesarean sections is performed because of a scar uterus. Objective of this study was to analyse the epidemiological and clinical factors of iterative caesarean sections in the gynecology-obstetrics department at the Teaching Hospital of Cocody (Abidjan).Methods: This was a retrospective and descriptive study conducted from June 1st, 2018 to May 31st, 2019, including 349 iterative caesarean section cases.Results: The first iterative C-section accounted for 16.1% of the C-section indications during the study period. The average age of the patients was 30 years. Nearly half of the patients practiced in the informal sector 47.9%, were uneducated in 38.1% of cases and lived with a partner in 73.1% of cases. The majority of patients in this series 75.1% performed at least 4 ANCs. Patients were followed by prenatal visits in 61% of cases by midwives and in 8.6% of cases had an inter-reproductive space of less than 18 months. This study patients were evacuated in 46.4% of cases. Acute fetal distress was the first indication of first iterative caesarean section with 20.3% of cases. Emergency caesarean sections accounted for 84.4% of the cases in this series. Authors found maternal death 0.3% and 6.7% perinatal mortality.Conclusions: The iterative caesarean section is a caesarean section likely to cause difficulties and complications per- operative. Although in constant improvement the prognosis of the mother-child couple still remains a problem in this context, prenatal monitoring should be the prerogative of obstetrician gynecologists

Investigating avian influenza infection hotspots in old-world shorebirds

Heterogeneity in the transmission rates of pathogens across hosts or environments may produce disease hotspots, which are defined as specific sites, times or species associations in which the infection rate is consistently elevated. Hotspots for avian influenza virus (AIV) in wild birds are largely unstudied and poorly understood. A striking feature is the existence of a unique but consistent AIV hotspot in shorebirds (Charadriiformes) associated with a single species at a specific location and time (ruddy turnstone Arenaria interpres at Delaware Bay, USA, in May). This unique case, though a valuable reference, limits our capacity to explore and understand the general properties of AIV hotspots in shorebirds. Unfortunately, relatively few shorebirds have been sampled outside Delaware Bay and they belong to only a few shorebird families; there also has been a lack of consistent oropharyngeal sampling as a complement to cloacal sampling. In this study we looked for AIV hotspots associated with other shorebird species and/or with some of the larger congregation sites of shorebirds in the old world. We assembled and analysed a regionally extensive dataset of AIV prevalence from 69 shorebird species sampled in 25 countries across Africa and Western Eurasia. Despite this diverse and extensive coverage we did not detect any new shorebird AIV hotspots. Neither large shorebird congregation sites nor the ruddy turnstone were consistently associated with AIV hotspots. We did, however, find a low but widespread circulation of AIV in shorebirds that contrast with the absence of AIV previously reported in shorebirds in Europe. A very high AIV antibody prevalence coupled to a low infection rate was found in both first-year and adult birds of two migratory sandpiper species, suggesting the potential existence of an AIV hotspot along their migratory flyway that is yet to be discovered

Culex pipiens, an Experimental Efficient Vector of West Nile and Rift Valley Fever Viruses in the Maghreb Region

West Nile fever (WNF) and Rift Valley fever (RVF) are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV) circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV) re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 107.8 and 108.5 plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14–21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology

Madagascar’s extraordinary biodiversity: Evolution, distribution, and use

Madagascar's biota is hyperdiverse and includes exceptional levels of endemicity. We review the current state of knowledge on Madagascar's past and current terrestrial and freshwater biodiversity by compiling and presenting comprehensive data on species diversity, endemism, and rates of species description and human uses, in addition to presenting an updated and simplified map of vegetation types. We report a substantial increase of records and species new to science in recent years; however, the diversity and evolution of many groups remain practically unknown (e.g., fungi and most invertebrates). Digitization efforts are increasing the resolution of species richness patterns and we highlight the crucial role of field- and collections-based research for advancing biodiversity knowledge and identifying gaps in our understanding, particularly as species richness corresponds closely to collection effort. Phylogenetic diversity patterns mirror that of species richness and endemism in most of the analyzed groups. We highlight humid forests as centers of diversity and endemism because of their role as refugia and centers of recent and rapid radiations. However, the distinct endemism of other areas, such as the grassland-woodland mosaic of the Central Highlands and the spiny forest of the southwest, is also biologically important despite lower species richness. The documented uses of Malagasy biodiversity are manifold, with much potential for the uncovering of new useful traits for food, medicine, and climate mitigation. The data presented here showcase Madagascar as a unique living laboratory for our understanding of evolution and the complex interactions between people and nature. The gathering and analysis of biodiversity data must continue and accelerate if we are to fully understand and safeguard this unique subset of Earth's biodiversity

Madagascar’s extraordinary biodiversity: Threats and opportunities

Madagascar's unique biota is heavily affected by human activity and is under intense threat. Here, we review the current state of knowledge on the conservation status of Madagascar's terrestrial and freshwater biodiversity by presenting data and analyses on documented and predicted species-level conservation statuses, the most prevalent and relevant threats, ex situ collections and programs, and the coverage and comprehensiveness of protected areas. The existing terrestrial protected area network in Madagascar covers 10.4% of its land area and includes at least part of the range of the majority of described native species of vertebrates with known distributions (97.1% of freshwater fishes, amphibians, reptiles, birds, and mammals combined) and plants (67.7%). The overall figures are higher for threatened species (97.7% of threatened vertebrates and 79.6% of threatened plants occurring within at least one protected area). International Union for Conservation of Nature (IUCN) Red List assessments and Bayesian neural network analyses for plants identify overexploitation of biological resources and unsustainable agriculture as themost prominent threats to biodiversity. We highlight five opportunities for action at multiple levels to ensure that conservation and ecological restoration objectives, programs, and activities take account of complex underlying and interacting factors and produce tangible benefits for the biodiversity and people of Madagascar