It has been suggested that an intermediate-massive black hole (IMBH) with mass 10 super(3-5) M sub(middot in circle) could fall into the galactic center (GC) and form a massive black hole binary ...(MBHB) with the central supermassive black hole, but current observations are not sensitive to constrain all mass and distance ranges. Motivated by the recent discovery that MBHBs could enhance the rate of tidal-disruption events (TDEs) of stellar objects, we investigate the prospect of using stellar-disruption rate to probe IMBHs in the GC. We incorporated the perturbation by an IMBH into the loss-cone theory and calculated the stellar-disruption rates in the GC. We found that an IMBH heavier than 2000 M sub(middot in circle) could distinguishably enhance the stellar-disruption rate. By comparing observations of Sgr A* with the fall-back model for stellar debris, we suggested that the TDE rate in our Galaxy should not significantly exceed 0.002 yr super(-1), therefore a fraction of the parameter space for the IMBH, concentrating at the high-mass end, can already be excluded. To derive constraint in the remaining parameter space, it is crucial to observationally confirm or reject the stellar-disruption rate between 10 super(-4) and 10 super(-2) yr super(-1), and we discussed possible strategies to make such measurements.
Rural-to-urban migrant workers are a large marginalised population in urban China. Prevalence estimates of common mental health problems (CMHPs) in previous studies varied widely and very few studies ...have investigated migration-related factors of CMHPs in migrant workers. The objective of this study was to determine the prevalence and risk factors of CMHPs among Chinese migrant workers.
A random sample of 3031 migrant workers of ten manufacturing factories in Shenzhen, China, completed a standardised questionnaire containing socio-demographic and migration-related variables and the Chinese 12-item General Health Questionnaire (GHQ-12). A GHQ-12 score of three or higher was used to denote the presence of CMHPs.
The prevalence of CMHPs was 34.4% in Chinese migrant workers. In multiple logistic regression, risk factors for CMHPs included being 16-25 years old (odd ratio OR 1.65, 95% confidence interval CI 1.28, 2.12), being 26-35 years old (OR 1.36, 95% CI: 1.05, 1.75), low monthly income (OR 1.42, 95% CI 1.04, 1.92), poor living condition (OR: 1.76, 95% CI: 1.22, 2.54), physical illness in the past 2 weeks (OR 1.72, 95% CI 1.43, 2.05), having worked in many cities (OR 1.34, 95% CI 1.03, 1.74), infrequently visiting hometown (OR 1.56, 95% CI 1.22, 1.99), poor Mandarin proficiency (OR 1.51, 95%CI 1.13, 2.01), a low level of perceived benefits of migration (OR 1.33, 95% CI 1.14, 1.55) and working more than 8 h/day (OR 1.39, 95% CI 1.14, 1.70).
CMHPs are very prevalent among Chinese migrant workers. Given the large number of Chinese migrant workers, there is an urgent need to address the mental health burden of China's migrant worker population.
Context. The progenitors of many core-collapse supernovae (CCSNe) are expected to be in binary systems. After the SN explosion in a binary, the companion star may suffer from mass stripping and be ...shock heated as a result of the impact of the SN ejecta. If the binary system is disrupted by the SN explosion, the companion star is ejected as a runaway star, and in some cases as a hypervelocity star. Aims. By performing a series of three-dimensional (3D) hydrodynamical simulations of the collision of SN ejecta with the companion star, we investigate how CCSN explosions affect their binary companion. Methods. We use the BEC stellar evolution code to construct the detailed companion structure at the moment of SN explosion. The impact of the SN blast wave on the companion star is followed by means of 3D smoothed particle hydrodynamics (SPH) simulations using the Stellar GADGET code. Results. For main-sequence (MS) companion stars, we find that the amount of removed stellar mass, the resulting impact velocity, and the chemical contamination of the companion that results from the impact of the SN ejecta strongly increases with decreasing binary separation and increasing explosion energy. Their relationship can be approximately fitted by power laws, which is consistent with the results obtained from impact simulations of Type Ia SNe. However, we find that the impact velocity is sensitive to the momentum profile of the outer SN ejecta and, in fact, may decrease with increasing ejecta mass, depending on the modeling of the ejecta. Because most companion stars to Type Ib/c CCSNe are in their MS phase at the moment of the explosion, combined with the strongly decaying impact effects with increasing binary separation, we argue that the majority of these SNe lead to inefficient mass stripping and shock heating of the companion star following the impact of the ejecta. Conclusions. Our simulations show that the impact effects of Type Ib/c SN ejecta on the structure of MS companion stars, and thus their long-term post-explosion evolution, is in general not dramatic. We find that at most 10% of their mass is lost and their resulting impact velocities are less than 100 km s-1.
ABSTRACT
The project MOMO (Multiwavelength Observations and Modelling of OJ 287) was set up to test predictions of binary supermassive black hole (SMBH) scenarios and to understand disc–jet physics ...of the blazar OJ 287. After a correction, the precessing binary (PB) SMBH model predicted the next main outburst of OJ 287 in 2022 October, making the outburst well observable and the model testable. We have densely covered this period in our ongoing multifrequency radio, optical, ultraviolet (UV), and X-ray monitoring. The predicted outburst was not detected. Instead, OJ 287 was at low optical–UV emission levels, declining further into November. The predicted thermal bremsstrahlung spectrum was not observed either, at any epoch. Further, applying scaling relations, we estimate an SMBH mass of OJ 287 of 108 M⊙. The latest in a sequence of deep low states that recur every 1–2 yr is used to determine an upper limit on the Eddington ratio and on the accretion-disc luminosity. This limit is at least a factor of 10 lower than required by the PB model with its massive primary SMBH of >1010 M⊙. All these results favour alternative binary SMBH models of OJ 287 that require neither strong orbital precession nor a very large mass of the primary SMBH.
Neonatal sepsis is a major cause of neonatal deaths in Asia but data remain scarce. We aimed to investigate the causative organisms and antibiotic resistance in neonatal care units in China, ...Malaysia, Hong Kong and Thailand.
Prospective cohort study of neonatal sepsis defined as positive culture of a single potentially pathogenic organism from blood or cerebrospinal fluid differentiated into early-onset sepsis (EOS) occurring <3 days of birth and late-onset sepsis (LOS) ≥3 days after birth.
During the study period, there were 963 episodes of neonatal sepsis. The incidence of EOS was 0.62 (95% CI 0.45 to 0.82) per 1000 live births or 4.91 (95% CI 4.22 to 5.68) per 1000 admissions while the incidence of LOS was 5.00 (95% CI 4.51 to 5.53) per 1000 live births or 21.22 (95% CI 19.79 to 22.77) per 1000 admissions. The incidence of Group B Streptococcus (GBS) sepsis was low but remained the most common single pathogen for EOS among inborn babies. Klebsiella spp. was the most common Gram-negative organism causing most deaths. The case-fatality was 7.0% (95% CI 3.9% to 12.0%) for EOS and 16.0% (95% CI 13.7% to 19.0%) for LOS, and was significantly different between participating units after adjusting for potential confounders. Of all Gram-negative organisms, 47%, 37% and 32% were resistant to third-generation cephalosporins, gentamicin or both, respectively.
The pattern of EOS in Asian settings is similar to that in industrialised countries with low incidence of GBS sepsis. The important features of neonatal sepsis in Asia are the burden of Klebsiella spp. and high level of antibiotic resistance. These should be addressed while developing measures to reduce neonatal mortality due to infection.
The black tiger shrimp (Penaeus monodon) is an ecologically and economically important penaeid species and is widely distributed in the Indo-Pacific region. Here we investigated the genetic diversity ...of P. monodon (n = 355) from eight geographical regions by genotyping at 10 microsatellite loci. The average observed heterozygosity at various loci ranged from 0.638 to 0.743, indicating a high level of genetic variability in this region. Significant departures from Hardy-Weinberg equilibrium caused by heterozygote deficiency were recorded for most loci and populations. Pairwise FST and RST values revealed genetic differentiation among the populations. Evidence from the assignment test showed that the populations in the West Indian Ocean were unique, whereas other populations examined were partially admixed. In addition, the non-metric multidimensional scaling analysis indicated the presence of three geographic groups in the Indo-Pacific region, i.e. the African populations, a population from western Thailand and the remaining populations as a whole. We also sequenced and analysed the mitochondrial control region (mtCR) in these shrimp stocks to determine whether the nuclear and mitochondrial genomes show a similar pattern of genetic differentiation. A total of 262 haplotypes were identified, and nucleotide divergence among haplotypes ranged from 0.2% to 16.3%. Haplotype diversity was high in all populations, with a range from 0.969 to 1. Phylogenetic analysis using the mtCR data revealed that the West Indian Ocean populations were genetically differentiated from the West Pacific populations, consistent with the microsatellite data. These results should have implications for aquaculture management and conservation of aquatic diversity.
Objectives
The interactions between nutritional supplementation and physical activity on changes in physical function among older adults remain unclear. The primary objective of this study was to ...examine the impact of nutritional supplementation plus structured physical activity on 400M walk capacity in mobility-limited older adults across two sites (Boston, USA and Stockholm, Sweden).
Design
All subjects participated in a physical activity program (3x/week for 24 weeks), involving walking, strength, balance, and flexibility exercises. Subjects were randomized to a daily nutritional supplement (150kcal, 20g whey protein, 800 IU vitamin D) or placebo (30kcal, non-nutritive).
Setting
Participants were recruited from urban communities at 2 field centers in Boston MA USA and Stockholm SWE.
Participants
Mobility-limited (Short Physical Performance Battery (SPPB) ≤9) and vitamin D insufficient (serum 25(OH) D 9 - 24 ng/ml) older adults were recruited for this study.
Measurements
Primary outcome was gait speed assessed by the 400M walk. Results: 149 subjects were randomized into the study (mean age=77.5±5.4; female=46.3%; mean SPPB= 7.9±1.2; mean 25(OH)D=18.7±6.4 ng/ml). Adherence across supplement and placebo groups was similar (86% and 88%, respectively), and was also similar across groups for the physical activity intervention (75% and 72%, respectively). Both groups demonstrated an improvement in gait speed with no significant difference between those who received the nutritional supplement compared to the placebo (0.071 and 0.108 m/s, respectively (p=0.06)). Similar effects in physical function were observed using the SPPB. Serum 25(OH)D increased in supplemented group compared to placebo 7.4 ng/ml versus 1.3 ng/ml respectively.
Conclusion
Results suggest improved gait speed following physical activity program with no further improvement with added nutritional supplementation.
Abstract
Based on our dedicated Swift monitoring program, MOMO, OJ 287 is one of the best-monitored blazars in the X-ray–UV–optical regime. Here, we report results from our accompanying, dense, ...multifrequency (1.4–44 GHz) radio monitoring of OJ 287 between 2015 and 2022 covering a broad range of activity states. Fermi
γ
-ray observations were added. We characterize the radio flux and spectral variability in detail, including discrete correlation function and other variability analyses, and discuss its connection with the multiwavelength emission. Deep fades of the radio and optical–UV fluxes are found to occur every 1–2 yr. Further, it is shown that a precursor flare of thermal bremsstrahlung predicted by one of the binary supermassive black hole (SMBH) models of OJ 287 was absent. We then focus on the nature of the extraordinary, nonthermal, 2016/2017 outburst that we initially discovered with Swift. We interpret it as the latest of the famous optical double-peaked outbursts of OJ 287, favoring binary scenarios that do not require a highly precessing secondary SMBH.
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