Explore the vast range of titles available.

The production of particle–antiparticle pairs in a vacuum — the Schwinger effect — requires extreme conditions that are out of reach of tabletop experiments. A mesoscopic simulation of this phenomenon has now been carried out in graphene devices.

Graphene-based moiré superlattices have recently emerged as a unique class of tuneable solid-state systems that exhibit significant optoelectronic activity. Local probing at length scales of the superlattice should provide deeper insight into the microscopic mechanisms of photoresponse and the exact role of the moiré lattice. Here, we employ a nanoscale probe to study photoresponse within a single moiré unit cell of minimally twisted bilayer graphene. Our measurements reveal a spatially rich photoresponse, whose sign and magnitude are governed by the fine structure of the moiré lattice and its orientation with respect to measurement contacts. This results in a strong directional effect and a striking spatial dependence of the gate-voltage response within the moiré domains. The spatial profile and carrier-density dependence of the measured photocurrent point towards a photo-thermoelectric induced response that is further corroborated by good agreement with numerical simulations. Our work shows sub-diffraction photocurrent spectroscopy is an exceptional tool for uncovering the optoelectronic properties of moiré superlattices. Here, the authors use a nanoscale probe to study the photoresponse within a single moiré unit cell of minimally twisted bilayer graphene, and observe an intricate photo-thermoelectric response attributed to the Seebeck coefficient variation at AB-BA domain boundaries.

The photoexcitation life cycle from incident photon (and creation of photoexcited electron–hole pair) to ultimate extraction of electrical current is a complex multiphysics process spanning across a range of spatiotemporal scales of quantum materials. Photocurrent is sensitive to a myriad of physical processes across these spatiotemporal scales, and over the past decade it has emerged as a versatile probe of electronic states, Bloch band quantum geometry, quantum kinetic processes and device characteristics of quantum materials. This Technical Review outlines the key multiphysics principles of photocurrent diagnostics, for resolving band structure and characterizing topological materials, for disentangling distinct types of carrier scattering that can range from femtosecond to nanosecond timescales and for enabling new types of remote-sensing protocols and photocurrent nanoscopy. These distinctive capabilities underscore photocurrent diagnostics as a novel multiphysics probe for a growing class of quantum materials with properties governed by physics spanning multiple spatiotemporal scales.Photocurrent can be used to reveal the out-of-equilibrium properties of quantum materials over a range of spatiotemporal scales. This Technical Review outlines the principles of photocurrent diagnostics and how it can be used to probe electronic states, quantum geometry and quantum kinetics of materials.

In quantizing magnetic fields, graphene superlattices exhibit a complex fractal spectrum often referred to as the Hofstadter butterfly. It can be viewed as a collection of Landau levels that arise from quantization of Brown-Zak minibands recurring at rational ( p / q ) fractions of the magnetic flux quantum per superlattice unit cell. Here we show that, in graphene-on-boron-nitride superlattices, Brown-Zak fermions can exhibit mobilities above 10 6  cm 2  V −1  s −1 and the mean free path exceeding several micrometers. The exceptional quality of our devices allows us to show that Brown-Zak minibands are 4 q times degenerate and all the degeneracies (spin, valley and mini-valley) can be lifted by exchange interactions below 1 K. We also found negative bend resistance at 1/ q fractions for electrical probes placed as far as several micrometers apart. The latter observation highlights the fact that Brown-Zak fermions are Bloch quasiparticles propagating in high fields along straight trajectories, just like electrons in zero field. Here, the authors show that Brown-Zak fermions in graphene-on-boron-nitride superlattices exhibit mobilities above 10 6  cm 2 /V s and micrometer scale ballistic transport.

Nepal has achieved a significant reduction of TB incidence over the past decades. Nevertheless, TB patients continue to experience barriers in access, diagnosis and completion of the treatment. The main objective of this study was to explore the factors affecting the access to the health services, diagnosis and the treatment completion for TB patients in central and western Nepal. Data were collected using in-depth interviews (IDI) with the TB patients (n = 4); Focus Group Discussions (FGDs) with TB suspected patients (n = 16); Semi Strucutred Interviews (SSIs) with health workers (n = 24) and traditional healers (n = 2); and FGDs with community members (n = 8). All data were audio recorded, transcribed and translated to English. All transcriptions underwent thematic analysis using qualitative data analysis software: Atlas.ti. Barriers to access to the health centre were the long distance, poor road conditions, and costs associated with travelling. In addition, lack of awareness of TB and its consequences, and the belief, prompted many respondents to visit traditional healers. Early diagnosis of TB was hindered by lack of trained health personnel to use the equipment, lack of equipment and irregular presence of health workers. Additional barriers that impeded the adherence and treatment completion were the need to visit health centre daily for DOTS treatment and associated constraints, complex treatment regimen, and the stigma. Barriers embedded in health services and care seekers' characteristics can be dealt by strengthening the peripheral health services. A continuous availability of (trained) human resources and equipment for diagnosis is critical. As well as increasing the awareness and collaborating with the traditional healers, health services utilization can be enhanced by compensating the costs associated with it, including the modification in current DOTS strategy by providing medicine for a longer term under the supervision of a family member, peer or a community volunteer.

Pluripotent stem cells (PSCs) are capable of dynamic interconversion between distinct substates; however, the regulatory circuits specifying these states and enabling transitions between them are not well understood. Here we set out to characterize transcriptional heterogeneity in mouse PSCs by single-cell expression profiling under different chemical and genetic perturbations. Signalling factors and developmental regulators show highly variable expression, with expression states for some variable genes heritable through multiple cell divisions. Expression variability and population heterogeneity can be influenced by perturbation of signalling pathways and chromatin regulators. Notably, either removal of mature microRNAs or pharmacological blockage of signalling pathways drives PSCs into a low-noise ground state characterized by a reconfigured pluripotency network, enhanced self-renewal and a distinct chromatin state, an effect mediated by opposing microRNA families acting on the Myc / Lin28 /let-7 axis. These data provide insight into the nature of transcriptional heterogeneity in PSCs. This study uses single-cell expression profiling of pluripotent stem cells after various perturbations, and uncovers a high degree of variability that can be inherited through cell divisions—modulating microRNA or external signalling pathways induces a ground state with reduced gene expression heterogeneity and a distinct chromatin profile. Gene expression variation in pluripotency Although it is recognized that pluripotent stem cells switch dynamically between distinct substates, the gene regulatory networks specifying the states and governing transitions between them are not well defined. Using single-cell expression profiling of mouse pluripotent stem cells subjected to chemical and genetic perturbations, George Daley and colleagues establish how transcriptional networks are dynamically reconfigured to drive distinct states of pluripotency. They observe a high degree of variability that can be inherited through cell divisions and find that modulating microRNA or external signalling pathways lowers the heterogeneity in gene expression and induces a distinct epigenetic state.

Since their discovery as key regulators of early animal development, microRNAs now are recognized as widespread regulators of gene expression. Despite their abundance, little is known regarding the regulation of microRNA biogenesis. We show that three highly conserved muscle-specific microRNAs, miR-1, miR-133 and miR-206, are robustly induced during the myoblast-myotube transition, both in primary human myoblasts and in the mouse mesenchymal$C_{2}C_{12}$stem cell line. These microRNAs were not induced during osteogenic conversion of$C_{2}C_{12}$cells. Moreover, both loci encoding miR-1, miR-l-1, and miR-1-2, and two of the three encoding miR-133, miR-133a-1 and miR-133a-2, are strongly induced during myogenesis. Some of the induced microRNAs are in intergenic regions, whereas two are transcribed in the opposite direction to the nonmuscle-specific gene in which they are embedded. By using CHIP analysis, we demonstrate that the myogenic factors Myogenin and MyoD bind to regions upstream of these microRNAs and, therefore, are likely to regulate their expression. Because miR-1 and miR-206 are predicted to repress similar mRNA targets, our work suggests that induction of these microRNAs is important in regulating the expression of muscle-specific proteins.

In 2020, 149 million children under the age of five were estimated to be stunted globally. Around half of deaths among children under 5 years of age are related to under-nutrition. Objective of this study is to determine the association between safely managed sanitation and childhood stunting among under-five years old children in Myanmar. This cross-sectional analytical study was conducted in 16 townships across three regions and five states in Myanmar. Multiple logistic regressions analysis was performed to determine the associations. This study found that 327 (27.09%) under-five children were stunted among a total of 1207 children in Myanmar. Children with unsafely managed sanitation were 2.88 times more likely to be stunting compared with children who access to safely managed sanitation services (AOR = 2.88, 95% CI: 2.16 to 3.85; p-value <0.01). Other associated factors for childhood stunting were needs 1–15 minutes for water collection (AOR = 2.07, 95% CI: 1.46 to 2.94; p-value <0.01), 15–60 minutes for water collection times (AOR = 1.55, 95% CI: 1.08 to 2.23; p-value 0.02), improper waste water disposal (AOR = 1.99, 95% CI: 1.47 to 2.70; p-value <0.01), boys children (AOR = 4.49, 95% CI: 3.30 to 6.12; p-value <0.01), did not take vitamin A supplements(AOR = 1.64, 95% CI: 1.22 to 2.20; p-value <0.01), mothers height shorter than 153.4cm (AOR = 1.94, 95% CI: 1.45 to 2.58; p-value <0.01), and the lower minimal diet diversity (AOR = 1.47, 95% CI: 1.08 to 2.01; p-value 0.02). More access to safely managed sanitation facilities, technical sharing for proper waste water disposal, promoting household water supply system, health promotion for children’s diet eating pattern, and regular support for Vitamin A supplementation are critical to reduce childhood stunting among children under the age of five in Myanmar.

Road traffic accidents (RTAs) continue to pose a significant menace to global public health in the form of a high incidence of mortality, disability and economic expense. Their space-time trends are of importance for policy decision-making. This particular study employed spatial analysis to identify high-risk zones and found significant clustering of accidents in urban centers as well as increasing semi-urban and rural vulnerabilities, supporting the need for safety interventions and road infrastructure improvements in Nepal. This paper aims to determine and analyze the incidence of RTAs in Nepal from 2019 to 2022, primarily focusing on vehicle-types and spatial distribution. Data from all seven provinces and Kathmandu Valley Traffic Police Office were analyzed to examine RTAs patterns across 77 districts of Nepal. The data were processed and visualized using Quantum GIS (QGIS), and spatial analysis performed using Global and Local Moran's I statistics, along with Local Indicators of Spatial Association (LISA), to identify spatial clusters of accidents. This study identified statistically significant spatial clustering of vehicle types involved in RTAs. High-High (HH) clusters, indicating areas with elevated accident rates surrounded by similarly high-risk zones were concentrated in urban centers particularly Kathmandu, Lalitpur, and Bhaktapur. Conversely, Low-Low (LL) clusters, reflecting lower accident rates in sparsely populated regions, were observed in rural areas. Temporal analysis revealed a steady rise in RTAs incidence, with rates increasing from 63.35 per 100,000 population in 2019-2020 (Moran's I = 0.741) to 94.46 in 2020-2021 (Moran's I = 0.595) and 123.05 in 2021-2022 (Moran's I = 0.556). This present study observed the growing incidence of RTAs in Nepal. The results highlight the critical need for geographically tailored road safety interventions with priority given to urban and semi-urban zones. Effective strategies should emphasize enhanced road traffic law enforcement, strict regulation of commercial and two-wheeled vehicles as well as targeted infrastructure upgrades in an effective manner.

Gallbladder cancer (GBC) is a rare, highly fatal disease with diagnosis in advanced stage and low survival rate. Nepal ranked 4th position with highest rates of GBC for 10 countries in 2020. To find the association between socio-demographic, behavioral and environmental factors associated with the development of GBC. A case-control study was conducted in 2021/22 with newly diagnosed gallbladder cancer cases from three cancer-specialized hospitals and one tertiary (superspeciality) hospital. Controls were selected from the same tertiary hospital and one additional hospital providing services to gallbladder pathologies for a huge population, making a total of five hospitals involved in the study. The ratio of cases to control was 1:1. The data collection was done through telephonic interviews using structured questionnaires. The risk factors for GBC were assessed by using unconditional logistic regression to find odds ratios and 95% confidence level for bivariate and multivariate analysis. The statistical analysis was carried out in STATA 18. A total of 240 respondents were enrolled in the study, among them half were GBC patients (cases) and half were gallbladder patients (controls). The average age of the respondents was 54.82±12.3 years, with female preponderance among both groups. On multivariate analysis, the risk factors studied were; parity ≥3 (AOR = 2.80, 95% CI: 1.17-6.66, P value 0.020), being ethnic group of Terai/Madhesi (AOR = 7.88, 95% CI: 3.16-19.66, P value <0.001), being Janajati (AOR = 3.36, 95% CI: 1.17-6.61, P value <0.001), having gallbladder related disease (AOR = 2.00, 95% CI:1.00-4.02, P value 0.049), consuming alcohol ≥100ml/day (AOR = 3.44, 95% CI:1.11-10.63, P value 0.032), exposed with pesticides ≥2 times in a year (AOR = 4.04, 95% CI: 1.27-12.89, P value 0.018) and consuming less vegetables and fruits (<1 times per day in a week) (AOR = 2.69, 95% CI:1.34-5.40, P value 0.005). The study reveals key GBC risk factors, offering vital insights for targeted screening, resource allocation, and public health measures to mitigate risks in Nepal.