Retired A Stars: The Effect of Stellar Evolution on the Mass Estimates of Subgiants

Doppler surveys have shown that the occurrence rate of Jupiter-mass planets appears to increase as a function of stellar mass. However, this result depends on the ability to accurately measure the masses of evolved stars. Recently, Lloyd (2011) called into question the masses of subgiant stars targeted by Doppler surveys. Lloyd argues that very few observable subgiants have masses greater than 1.5 Msun, and that most of them have masses in the range 1.0-1.2 Msun. To investigate this claim, we use Galactic stellar population models to generate an all-sky distribution of stars. We incorporate the effects that make massive subgiants less numerous, such as the initial mass function and differences in stellar evolution timescales. We find that these effects lead to negligibly small systematic errors in stellar mass estimates, in contrast to the roughly 50% errors predicted by Lloyd. Additionally, our simulated target sample does in fact include a significant fraction of stars with masses greater than 1.5 Msun, primarily because the inclusion of an apparent magnitude limit results in a Malmquist-like bias toward more massive stars, in contrast to the volume-limited simulations of Lloyd. The magnitude limit shifts the mean of our simulated distribution toward higher masses and results in a relatively smaller number of evolved stars with masses in the range 1.0-1.2 Msun. We conclude that, within the context of our present-day understanding of stellar structure and evolution, many of the subgiants observed in Doppler surveys are indeed as massive as main-sequence A stars.Comment: Accepted to ApJ, 5 pages, 3 figures; changed title, reworded introduction and conclusion

Non-CG methylation patterns shape the epigenetic landscape in Arabidopsis.

DNA methylation occurs in CG and non-CG sequence contexts. Non-CG methylation is abundant in plants and is mediated by CHROMOMETHYLASE (CMT) and DOMAINS REARRANGED METHYLTRANSFERASE (DRM) proteins; however, its roles remain poorly understood. Here we characterize the roles of non-CG methylation in Arabidopsis thaliana. We show that a poorly characterized methyltransferase, CMT2, is a functional methyltransferase in vitro and in vivo. CMT2 preferentially binds histone H3 Lys9 (H3K9) dimethylation and methylates non-CG cytosines that are regulated by H3K9 methylation. We revealed the contributions and redundancies between each non-CG methyltransferase in DNA methylation patterning and in regulating transcription. We also demonstrate extensive dependencies of small-RNA accumulation and H3K9 methylation patterning on non-CG methylation, suggesting self-reinforcing mechanisms between these epigenetic factors. The results suggest that non-CG methylation patterns are critical in shaping the landscapes of histone modification and small noncoding RNA

Measurement of Thermal Stress in Railroad Rails Using Ultrasonic SH Waves

The use of welded joints in railroad tracks has led to problems of rail buckling brought about by the development of large compressive stresses during hot days. On cold days, tensile stresses can actually fracture the rail. In order to prevent this source of derailments, it is desirable to develop an easily used instrument to measure the level of stress in an arbitrary section of track in the field. Ultrasonic birefringence, acoustic emission and certain magnetic phenomena have all been used to attack this problem but they all suffer from the necessity for calibrating the sensor under stress-free conditions in order to correct for metallurgical structure variations. A new ultrasonic technique based on using surface skimming shear horizontal ultrasonic waves generated and detected by EMATs was investigated here because it rigorously eliminates the effects of metallurgical texture as well as unreliable coupling of the transducer to the part. Tests on sections of rail mounted in a 200,000 pound testing machine at the University of New Mexico demonstrated that the theory for the basic phenomenon is correct and that the stress level can be measured in spite of the presence of considerable texture in the rail microstructure

Provider Use of Risk Stratification Tools for PE and CTA Ordering Practices

Aims for Improvement Quantify utilization of clinical decision tools, D-dimer and CTA-PE at TJUH and compare to benchmark and implement the logic seen in the adjacent QR code to an EPIC pop-u

The Interaction of the Chaperonin Tailless Complex Polypeptide 1 (Tcp1) Ring Complex (Tric) with Ribosome-Bound Nascent Chains Examined Using Photo-Cross-Linking

The eukaryotic chaperonin tailless complex polypeptide 1 (TCP1) ring complex (TRiC) (also called chaperonin containing TCP1 [CCT]) is a hetero-oligomeric complex that facilitates the proper folding of many cellular proteins. To better understand the manner in which TRiC interacts with newly translated polypeptides, we examined its association with nascent chains using a photo-cross-linking approach. To this end, a series of ribosome-bound nascent chains of defined lengths was prepared using truncated mRNAs. Photoactivatable probes were incorporated into these 35S- labeled nascent chains during translation. Upon photolysis, TRiC was cross-linked to ribosome-bound polypeptides exposing at least 50–90 amino acids outside the ribosomal exit channel, indicating that the chaperonin associates with much shorter nascent chains than indicated by previous studies. Cross-links were observed for nascent chains of the cytosolic proteins actin, luciferase, and enolase, but not to ribosome-bound preprolactin. The pattern of cross-links became more complex as the nascent chain increased in length. These results suggest a chain length–dependent increase in the number of TRiC subunits involved in the interaction that is consistent with the idea that the substrate participates in subunit-specific contacts with the chaperonin. Both ribosome isolation by centrifugation through sucrose cushions and immunoprecipitation with anti-puromycin antibodies demonstrated that the photoadducts form on ribosome-bound polypeptides. Our results indicate that TRiC/CCT associates with the translating polypeptide shortly after it emerges from the ribosome and suggest a close association between the chaperonin and the translational apparatus

Acute effects of mango leaf extract on cognitive function in healthy adults: a randomised, double-blind, placebo-controlled crossover study

Copyright \ua9 2024 Dodd, Kennedy, Johnson, Haworth, Greener and Jackson.Introduction: Extracts made from the leaves of the edible mango plant (Mangifera indica L., Anacardiaceae) have a long history of medicinal usage, most likely due to the presence of high levels of mangiferin, a polyphenol compound. Previous research has demonstrated that mango leaf extract (MLE) can beneficially modulate cognitive function in both animals and humans. This study aimed to assess the effects of an acute dose of 300 mg MLE (standardised to contain ≥60% mangiferin) on cognitive performance and mood in healthy adults. Methods: In this double-blind, placebo-controlled, crossover study, 114 healthy men and women (18–43 years) received either MLE or a matched placebo at each testing visit (separated by at least 7 days). Cognitive performance (including the cognitive demand battery) and mood were measured at 30, 180, and 300 min post-dose. Results: The results showed that, compared to placebo, the group taking MLE displayed a significant increase in serial 3 s and serial 7 s subtraction errors overall. There were no other significant effects on cognitive performance. Discussion: The results of the current study suggest that the consumption of 300 mg MLE in the absence of an observed multitasking psychological stressor does not improve cognitive performance or mood at up to 300 min post-dose. Due to the very limited nature of the effects and since they were observed among many analyses, these findings should be treated with caution. Clinical trial registration: http://ClinicalTrials.gov, identifier [NCT05182450]

A COVID-19-Based Modified Epidemiological Model and Technological Approaches to Help Vulnerable Individuals Emerge from the Lockdown in the UK

COVID-19 has shown a relatively low case fatality rate in young healthy individuals, with the majority of this group being asymptomatic or having mild symptoms. However, the severity of the disease among the elderly as well as in individuals with underlying health conditions has caused significant mortality rates worldwide. Understanding this variance amongst different sectors of society and modelling this will enable the different levels of risk to be determined to enable strategies to be applied to different groups. Long-established compartmental epidemiological models like SIR and SEIR do not account for the variability encountered in the severity of the SARS-CoV-2 disease across different population groups. The objective of this study is to investigate how a reduction in the exposure of vulnerable individuals to COVID-19 can minimise the number of deaths caused by the disease, using the UK as a case study. To overcome the limitation of long-established compartmental epidemiological models, it is proposed that a modified model, namely SEIR-v, through which the population is separated into two groups regarding their vulnerability to SARS-CoV-2 is applied. This enables the analysis of the spread of the epidemic when different contention measures are applied to different groups in society regarding their vulnerability to the disease. A Monte Carlo simulation (100,000 runs) along the proposed SEIR-v model is used to study the number of deaths which could be avoided as a function of the decrease in the exposure of vulnerable individuals to the disease. The results indicate a large number of deaths could be avoided by a slight realistic decrease in the exposure of vulnerable groups to the disease. The mean values across the simulations indicate 3681 and 7460 lives could be saved when such exposure is reduced by 10% and 20% respectively. From the encouraging results of the modelling a number of mechanisms are proposed to limit the exposure of vulnerable individuals to the disease. One option could be the provision of a wristband to vulnerable people and those without a smartphone and contact-tracing app, filling the gap created by systems relying on smartphone apps only. By combining very dense contact tracing data from smartphone apps and wristband signals with information about infection status and symptoms, vulnerable people can be protected and kept safer