1,223 research outputs found
Translation termination depends on the sequential ribosomal entry of eRF1 and eRF3.
Translation termination requires eRF1 and eRF3 for polypeptide-and tRNA-release on stop codons. Additionally, Dbp5/DDX19 and Rli1/ABCE1 are required; however, their function in this process is currently unknown. Using a combination of in vivo and in vitro experiments, we show that they regulate a stepwise assembly of the termination complex. Rli1 and eRF3-GDP associate with the ribosome first. Subsequently, Dbp5-ATP delivers eRF1 to the stop codon and in this way prevents a premature access of eRF3. Dbp5 dissociates upon placing eRF1 through ATP-hydrolysis. This in turn enables eRF1 to contact eRF3, as the binding of Dbp5 and eRF3 to eRF1 is mutually exclusive. Defects in the Dbp5-guided eRF1 delivery lead to premature contact and premature dissociation of eRF1 and eRF3 from the ribosome and to subsequent stop codon readthrough. Thus, the stepwise Dbp5-controlled termination complex assembly is essential for regular translation termination events. Our data furthermore suggest a possible role of Dbp5/DDX19 in alternative translation termination events, such as during stress response or in developmental processes, which classifies the helicase as a potential drug target for nonsense suppression therapy to treat cancer and neurodegenerative diseases
Phytochemical and Antimicrobial Screening of Native Plant Swertia Chirayita (Roxb. Ex Fleming) Karst From Rasuwa District of Nepal
Swertia chirayita is one of the highly traded medicinal plants of Nepal. This plant was chosen for investigation as folk medicines and then collected from the diverse habitats of Rasuwa district of Nepal and specimens have been checked and identified at National Herbarium and Plant Laboratories (NHPL), Godavari, Lalitpur. The identified plant was subjected to study physiochemical and biological activity. The stem, root and leaves of the plant were dried, made powder and mixed at the ratio of 1 : 1 : 1 and then extracted using methanol solvent by cold and warm method. The percentage yield from the plant was highest in warm methanol with 3.73%, followed by cold methanol with 2.28%. Plant extract showed the presence of phytochemicals like basic alka-loids, coumarin, glycosides, steroids, quinones, flavonoid and terpenoids. The antibacterial activity of the ex-tract showed significant bioactive by inhibiting the growth of selected pathogenic microbial species for the test. The zone of inhibition (ZOI) shown by the extracts was comparable to the standard antibiotics. Similar-ly, proximate composition was also carried out. The antioxidant activity of the sample was found to be 62.54% at 500 µg/mL and 15.32% at 100 µg/mL by radical scavenging method and showed significant antioxi-dants potential
Bandgap Profiling in CIGS Solar Cells Via Valence Electron Energy-Loss Spectroscopy
A robust, reproducible method for the extraction of relative bandgap trends from scanning transmission electron microscopy (STEM) based electron energy-loss spectroscopy (EELS) is described. The effectiveness of the approach is demonstrated by profiling the bandgap through a CuIn1-xGaxSe2 solar cell that possesses intentional Ga/(In + Ga) composition variation. The EELS-determined bandgap profile is compared to the nominal profile calculated from compositional data collected via STEM-based energy dispersive X-ray spectroscopy. The EELS based profile is found to closely track the calculated bandgap trends, with only a small, fixed offset difference. This method, which is particularly advantageous for relatively narrow bandgap materials and/or STEM systems with modest resolution capabilities (i.e., 100 meV), compromises absolute accuracy to provide a straightforward route for the correlation of local electronic structure trends with nanoscale chemical and physical structure/microstructure within semiconductor materials and devices. Published by AIP Publishing
Knowledge, attitudes, and practices associated with vitamin D supplementation: A cross-sectional online community survey of adults in the UK
OBJECTIVE: Assess knowledge, attitudes, and practices (KAPs) of a diverse population. Identify barriers and facilitators that inform routine vitamin D supplementation and self-care in the community setting. DESIGN: Cross-sectional online voluntary survey. Electronic survey link published on college Qualtrics platform and advertised widely. Study information provided with Participant Information Sheet. SETTING AND PARTICIPANTS: 556 community dwelling adults across the UK. METHODS: The overarching study included two phases, incorporating quantitative and qualitative methodologies. This paper reports findings from the first phase of the FABCOM-D (Facilitators and Barriers to Community (Healthy) Vitamin D status) study. Online survey questions were iteratively developed after background literature searches and piloted to ensure clarity and ease of understanding. Survey responses summarised using frequencies and percentages, and univariable and multivariable logistic regression models explored for any association. A p-value less than 0.05 was considered statistically significant. The Checklist for Reporting Results of Internet E-Surveys guided reporting. Statistical analysis performed using IBM SPSS software. MAIN OUTCOME MEASURES: Awareness of vitamin D information sources, health benefits and testing. Attitudes to supplementation, sun exposure and fortification. RESULTS: Three quarters of the community had some awareness of vitamin D and around half were taking supplements. The two most trusted sources of information included health professionals and the NHS website. Participants were willing to pay for supplements, supporting a self-care agenda. With increasing age, there was significant reduced intake of vitamin D supplements. This aspect needs to be explored further as this could be a concern in deficiency status in the elderly. There was acceptance of food fortification but uncertainty on how to balance food intake with supplementation. CONCLUSION: We were successful in eliciting views on KAPs around vitamin D from a community population including a large proportion of Black and Minority Ethnic individuals. The community wanted information and guidance to help manage individual vitamin D status, especially for high-risk groups, and on balancing supplementation, food fortification and sun exposure
First Principles Calculation of Elastic Properties of Solid Argon at High Pressures
The density and the elastic stiffness coefficients of fcc solid argon at high
pressures from 1 GPa up to 80 GPa are computed by first-principles
pseudopotential method with plane-wave basis set and the generalized gradient
approximation (GGA). The result is in good agreement with the experimental
result recently obtained with the Brillouin spectroscopy by Shimizu et al.
[Phys. Rev. Lett. 86, 4568 (2001)]. The Cauchy condition was found to be
strongly violated as in the experimental result, indicating large contribution
from non-central many-body force. The present result has made it clear that the
standard density functional method with periodic boundary conditions can be
successfully applied for calculating elastic properties of rare gas solids at
high pressures in contrast to those at low pressures where dispersion forces
are important.Comment: 4 pages, 5 figures, submitted to PR
All-dielectric magnetic metasurface for advanced light control in dual polarizations combined with high-Q resonances
Nanostructured magnetic materials provide an efficient tool for light manipulation on sub-nanosecond and sub-micron scales, and allow for the observation of the novel effects which are fundamentally impossible in smooth films. For many cases of practical importance, it is vital to observe the magneto-optical intensity modulation in a dual-polarization regime. However, the nanostructures reported on up to date usually utilize a transverse Kerr effect and thus provide light modulation only for p-polarized light. We present a concept of a transparent magnetic metasurface to solve this problem, and demonstrate a novel mechanism for magneto-optical modulation. A 2D array of bismuth-substituted iron-garnet nanopillars on an ultrathin iron-garnet slab forms a metasurface supporting quasi-waveguide mode excitation. In contrast to plasmonic structures, the all-dielectric magnetic metasurface is shown to exhibit much higher transparency and superior quality-factor resonances, followed by a multifold increase in light intensity modulation. The existence of a wide variety of excited mode types allows for advanced light control: transmittance of both p- and s-polarized illumination becomes sensitive to the medium magnetization, something that is fundamentally impossible in smooth magnetic films. The proposed metasurface is very promising for sensing, magnetometry and light modulation applications
Physical properties of Ba2Mn2Sb2O single crystals
We report both experimental and theoretical investigations of the physical properties of Ba2Mn2Sb2O single crystals. This material exhibits a hexagonal structure with lattice constants a=4.7029(15) and c=19.9401(27) , as obtained from powder x-ray diffraction measurements, and in agreement with structural optimization through density functional theory (DFT) calculations. The magnetic susceptibility and specific heat show anomalies at TN=60 K, consistent with antiferromagnetic ordering. However, the magnitude of TN is significantly smaller than the Curie-Weiss temperature (ΘCW 560 K), suggesting a magnetic system of reduced dimensionality. The temperature dependence of both the in-plane and out-of-plane resistivity changes from activated at TTx∼200 K to logarithmic at
Investigating self-reported efficacy of lifestyle medicine approaches to tackle erectile dysfunction: a cross-sectional eSurvey based study
Background: Erectile dysfunction (ED) is the most common sexual dysfunction in men. Some types of ED are amenable to treatment using lifestyle medicine approaches with or without pharmacotherapy. Aim: Investigate self-reported efficacy of lifestyle medicine approaches to tackle ED. Methods: A cross-sectional online survey of 1177 community dwelling adults explored the prevalence and methods used to tackle ED in the community setting. We examined differences between participants with and without ED. Variables associated with ED in univariable analyses were included in a multivariable logistic regression to identify variables independently associated with the condition. Outcomes: Self-reported measure: perceived effectiveness of lifestyle medicine interventions to tackle ED. Results: Most respondents (76.5%) had experienced ED, and this was associated with having a long-term condition, taking anti-hypertensive medication, hypercholesterolaemia and obesity. Medication was the most common management strategy overall (65.9%), followed by stress management (43.5%) and weight loss (40.4%). Over half (53.9%) did not use any lifestyle modification strategies to tackle ED. Only 7.0% of ED sufferers received a mental health assessment and 29.2% received other tests (e.g., blood test, medical imaging) by GPs. Cardiovascular training was identified as the best rated strategy by its users (37.8%). Supplements (35.1%) and weight training/physical activity (32.6%) were also positively rated. Clinical implications Structured education to general practitioners and community dwelling adults about the impact of lifestyle behaviour modification and how this could influence the appearance or trajectory of ED could help improve personal choice when tackling ED. Strengths and limitations: To our knowledge, this is the first study to collect eSurvey responses from community dwelling adults to gauge their reliance and perceived effectiveness of lifestyle medicine approaches to tackle ED. The principal limitation was the lack of follow-up, and not recording other information including lifestyle factors such as nutrition, smoking, and the use of alcohol and recreational drugs, which may have enabled a fuller exploration of the factors that could influence the primary outcome measures examined. Conclusion: Despite the high prevalence of ED, there is not enough awareness in the community setting about effective and low-cost lifestyle medicine strategies, including cardiovascular training and the use of supplements and weight training, to help tackle this common condition
Triage and diagnostic accuracy of Online Symptom Checkers: a systematic review
Background: In the context of a deepening global shortage of health workers, and particularly the COVID-19 pandemic, there is growing international interest in and use of online symptom checkers (OSCs). However, the evidence surrounding the safety and accuracy of OSCs remains inconclusive so far. The triage and diagnostic accuracy of these tools is an essential aspect that needs to be addressed before pushing any further implementation. Objective: This systematic review aimed to summarize the existing peer-reviewed literature evaluating the triage accuracy (directing users to appropriate services based on their presenting symptoms) and diagnostic accuracy of OSCs aimed at lay users for general health concerns. Methods: Searches were conducted in Medline, Embase, CINAHL, HMIC and Web of Science. We included peer-reviewed studies published in English between 1 January 2010 and 17 February 2022 with a quantitative assessment of triage and/or diagnostic accuracy of OSCs directed at lay users. We excluded tools supporting health professionals, and disease- or speciality-specific OSCs. Screening and data extraction were carried out independently by two reviewers for each study. We performed a descriptive narrative synthesis. Results: 21,284 studies were screened and 15 were included. Six studies reported on both triage and diagnostic accuracy, eight focused on triage accuracy, and one on diagnostic accuracy. Diagnostic and triage accuracy varied between studies and OSCs; most studies showed suboptimal diagnostic and triage accuracy. Frequency and urgency of the condition were the main variables that affected the levels of diagnostic and triage accuracy, along with specific features of the OSCs. The impact of each variable differed across tools and studies, making it difficult to draw any solid conclusions. Included studies had either a moderate or high risk of bias according to the revised tool for the Quality Assessment of Diagnostic Accuracy Studies 2. Conclusions: While OSCs have significant potential to provide accessible and accurate health advice and triage recommendations to users, more research is needed to validate their triage and diagnostic accuracy prior to wide scale adoption in community and healthcare settings. Future studies should aim to use a common methodology and/or agreed standard for evaluation to facilitate objective benchmarking and validation
Large anomalous Hall effect in single crystals of the kagome Weyl ferromagnet FeSn
The material class of kagome metals has rapidly grown and has been
established as a field to explore the interplay between electronic topology and
magnetism. In this work, we report a combined theoretical and experimental
study of the anomalous Hall effect of the ferromagnetic kagome metal FeSn.
The compound orders magnetically at 725 K and presents an easy-plane
anisotropy. Hall measurements in single crystals below room temperature yield
an anomalous Hall conductivity ,
which is found to depend weakly on temperature. This value is in good agreement
with the band-intrinsic contribution obtained by density-functional
calculations. Our calculations also yield the correct magnetic anisotropy
energy and predict the existence of Weyl nodes near the Fermi energy.Comment: 9 pages and 9 figures including supplemen
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