Modeling the Optical-X-ray Accretion Lag in LMC X-3: Insights Into Black-Hole Accretion Physics

The X-ray persistence and characteristically soft spectrum of the black hole X-ray binary LMC X-3 make this source a touchstone for penetrating studies of accretion physics. We analyze a rich, 10-year collection of optical/infrared (OIR) time-series data in conjunction with all available contemporaneous X-ray data collected by the ASM and PCA detectors aboard the Rossi X-ray Timing Explorer. A cross-correlation analysis reveals an X-ray lag of ~2 weeks. Motivated by this result, we develop a model that reproduces the complex OIR light curves of LMC X-3. The model is comprised of three components of emission: stellar light; accretion luminosity from the outer disk inferred from the time-lagged X-ray emission; and light from the X-ray-heated star and outer disk. Using the model, we filter a strong noise component out of the ellipsoidal light curves and derive an improved orbital period for the system. Concerning accretion physics, we find that the local viscous timescale in the disk increases with the local mass accretion rate; this in turn implies that the viscosity parameter alpha decreases with increasing luminosity. Finally, we find that X-ray heating is a strong function of X-ray luminosity below ~50% of the Eddington limit, while above this limit X-ray heating is heavily suppressed. We ascribe this behavior to the strong dependence of the flaring in the disk upon X-ray luminosity, concluding that for luminosities above ~50% of Eddington, the star lies fully in the shadow of the disk.Comment: Accepted in ApJ (12 pages long in emulateapj format

Hygiene along the continuum of care in the early post-natal period: an observational study in Nigeria.

BACKGROUND: Newborns delivered in healthcare facilities in low- and middle-income countries are at an increased risk of healthcare associated infections. Facility-based studies have focused primarily on healthcare worker behaviour during labour & delivery with limited attention to hygiene practices in post-natal care areas and largely ignore the wide variety of actors involved in maternal and neonatal care. METHODS: This exploratory mixed-methods study took place in six healthcare facilities in Nigeria where 31 structured observations were completed during post-natal care, discharge, and the first 6 hours after return to the home. Frequency of hand hygiene opportunities and hand hygiene actions were assessed for types of patient care (maternal and newborn care) and the role individuals played in caregiving (healthcare workers, cleaners, non-maternal caregivers). Qualitative interviews with mothers were completed approximately 1 week after facility discharge. RESULTS: Maternal and newborn care were performed by a range of actors including healthcare workers, mothers, cleaners and non-maternal caregivers. Of 291 hand hygiene opportunities observed at health facilities, and 459 observed in home environments, adequate hand hygiene actions were observed during only 1% of all hand hygiene opportunities. Adequate hand hygiene prior to cord contact was observed in only 6% (1/17) of cord contact related hand hygiene opportunities at healthcare facilities and 7% (2/29) in households. Discharge advice was infrequent and not standardised and could not be remembered by the mother after a week. Mothers reported discomfort around telling non-maternal caregivers to practice adequate hand hygiene for their newborn. CONCLUSIONS: In this setting, hand hygiene practices during post-natal care and the first 6 hours in the home environment were consistently inadequate. Effective strategies are needed to promote safe hand hygiene practices within the post-natal care ward and home in low resource, high-burden settings. Such strategies need to target not just mothers and healthcare workers but also other caregivers

Magnetic Field Amplification and Flat Spectrum Radio Quasars

We perform time-dependent, spatially-resolved simulations of blazar emission to evaluate several flaring scenarios related to magnetic-field amplification and enhanced particle acceleration. The code explicitly accounts for light-travel-time effects and is applied to flares observed in the flat spectrum radio quasar (FSRQ) PKS 0208-512, which show optical/{\gamma}-ray correlation at some times, but orphan optical flares at other times. Changes in both the magnetic field and the particle acceleration efficiency are explored as causes of flares. Generally, external Compton emission appears to describe the available data better than a synchrotron self-Compton scenario, and in particular orphan optical flares are difficult to produce in the SSC framework. X-ray soft-excesses, {\gamma}-ray spectral hardening, and the detections at very high energies of certain FSRQs during flares find natural explanations in the EC scenario with particle acceleration change. Likewise, optical flares with/without {\gamma}-ray counterparts can be explained by different allocations of energy between the magnetization and particle acceleration, which may be related to the orientation of the magnetic field relative to the jet flow. We also calculate the degree of linear polarization and polarization angle as a function of time for a jet with helical magnetic field. Tightening of the magnetic helix immediately downstream of the jet perturbations, where flares occur, can be sufficient to explain the increases in the degree of polarization and a rotation by >= 180 degree of the observed polarization angle, if light-travel-time effects are properly considered.Comment: 12 pages, 9 figures. Accepted for publication in MNRA

The effects of a workplace intervention on employees’ cortisol awakening response

Work-related stressors are known to adversely affect employees’ stress physiology, including the cortisol awakening response (CAR)–or the spike in cortisol levels shortly after people wake up that aids in mobilizing energy. A flat or blunted CAR has been linked to chronic stress and burnout. This daily diary study tested the effects of a workplace intervention on employed parents’ CAR. Specifically, we tested whether the effects of the intervention on CAR were moderated by the type of days (workday versus non-work day). Data came from 94 employed parents from an information technology firm who participated in the baseline and 12-month diurnal cortisol components of the Work, Family, and Health Study, a group-randomized field experiment. The workplace intervention was designed to reduce work-family conflict (WFC) and implemented after the baseline data collection. Diurnal salivary cortisol was collected on 4 days at both baseline and 12 months. Multilevel modeling revealed that the intervention significantly increased employees’ CAR at 12 months on non-workdays, but this was not evident on workdays or for employees in the usual practice condition. The results provide evidence that the intervention was effective in enhancing employees’ biological stress physiology particularly during opportunities for recovery that are more likely to occur on non-work days.National Institute on Aging (U01AG027669)Work, Family & Health Network (U01HD051217)Work, Family & Health Network (U01HD051218)Work, Family & Health Network (U01HD051256)Work, Family & Health Network (U01HD051276)U.S. Army Research Institute for the Behavioral and Social SciencesNational Institute for Occupational Safety and Health (U010H008788)Alfred P. Sloan Foundation (2004-12-4)William T. Grant Foundation (9844)National Institutes of Health (U.S.) (Penn State General Clinical Research Center. Grant M01-RR-10732

SMARTS OPTICAL AND INFRARED MONITORING OF 12 GAMMA-RAY BRIGHT BLAZARS

We present multiwavelength data for 12 blazars observed from 2008 to 2010 as part of an ongoing optical–infrared photometric monitoring project. Sources were selected to be bright, southern (δ < 20◦) blazars observed by the Fermi Gamma-Ray Space Telescope. Light curves are presented for the 12 blazars in BVRJK at near-daily cadence. We find that optical and infrared fluxes are well correlated in all sources. Gamma-ray bright flat spectrum radio quasars (FSRQs) in our sample have optical/infrared emission correlated with gamma-rays consistent with inverse Compton-scattering models. In FSRQs, variability amplitude increases toward IR wavelengths, consistent with the presence of a thermal accretion disk varying on significantly longer timescales than the jet. In BL Lac objects, variability is mainly constant, or increases toward shorter wavelength. FSRQs have redder optical–infrared colors when they are brighter,whileBLLac objects showno such trend. Several objects showcomplicated color–magnitude behavior: AO 0235+164 appears in two different states depending on its gamma-ray intensity. OJ 287 and 3C 279 show some hysteresis tracks in their color–magnitude diagrams. Individual flares may be achromatic or otherwise depart from the trend, suggesting different jet components becoming important at different times. We present a time-dependent spectral energy distribution of the bright FSRQ 3C 454.3 during its 2009 December flare, which is well fit by an external Compton model in the bright state, although day-to-day changes pose challenges to a simple one-zone model. All data from the SMARTS monitoring program are publicly available on our Web site

An Integrative, Multilevel, and Transdisciplinary Research Approach to Challenges of Work, Family, and Health

Recognizing a need for rigorous, experimental research to support the efforts of workplaces and policymakers in improving the health and wellbeing of employees and their families, the National Institutes of Health and the Centers for Disease Control and Prevention formed the Work, Family & Health Network (WFHN). The WFHN is implementing an innovative multisite study with a rigorous experimental design (adaptive randomization, control groups), comprehensive multilevel measures, a novel and theoretically based intervention targeting the psychosocial work environment, and translational activities. This paper describes challenges and benefits of designing a multilevel and transdisciplinary research network that includes an effectiveness study to assess intervention effects on employees, families, and managers; a daily diary study to examine effects on family functioning and daily stress; a process study to understand intervention implementation; and translational research to understand and inform diffusion of innovation. Challenges were both conceptual and logistical, spanning all aspects of study design and implementation. In dealing with these challenges, however, the WFHN developed innovative, transdisciplinary, multi-method approaches to conducting workplace research that will benefit both the research and business communities

Can a Flexibility/Support Initiative Reduce Turnover Intentions and Exits? Results from the Work, Family, and Health Network

We draw on panel data from a randomized field experiment to assess the effects of a flexibility/supervisor support initiative called STAR on turnover intentions and voluntary turnover among professional technical workers in a large firm. An unanticipated exogenous shock-the announcement of an impending merger-occurred in the middle of data collection. Both organizational changes reflect an emerging employment contract characterized by increasing employee temporal flexibility even as employers wield greater flexibility in reorganizing their workforces. We theorized STAR would reduce turnover intentions and actual turnover by making it more attractive to stay with the current employer. We found being in a STAR team (versus a usual practice team) lowered turnover intentions 12 months later and reduced the risk of voluntary turnover over almost three years. We also examined potential mechanisms accounting for the effects of these two organizational changes; STAR effects on reducing turnover intentions are partially mediated by reducing work-to-family conflict, family-to-work conflict, burnout, psychological distress, perceived stress, and increasing job satisfaction. The effect of learning about the merger on increasing turnover intentions is fully mediated by increased job insecurity. STAR also moderates the negative effects of learning about the merger on turnover intentions for different subgroups. Findings provide insights into the effectiveness of an organizational intervention, the dynamics of organizations, and how competing logics of two organizational changes affect employees' labor market expectations and behavior

Work/ family demands and cardiometabolic risk and sleep duration in extended care employees: multilevel findings from the Work, family and Health Network

The study investigates the associations of work-family conflict and other work and family conditions with objectively-measured outcomes cardiometabolic risk and sleep duration in a study of employees in nursing homes. Multilevel analyses are used to assess cross-sectional associations between employee and job characteristics and health in analyses of 1,524 employees in 30 extended care facilities in a single company. We examine work and family conditions in relation to two major study health outcomes: 1) a validated, Framingham cardiometabolic risk score based on measured blood pressure, cholesterol, glycosylated hemoglobin (HbA1c), body mass index (BMI), and self-reported tobacco consumption, and 2) wrist actigraphy-based measures of sleep duration. In fully-adjusted multi-level models, Work-To-Family conflict, but not Family-to-Work conflict was positively associated with cardiometabolic risk. Having a lower-level occupation (nursing assistants vs. nurses) was also associated with increased cardiometabolic risk, while being married and having younger children at home was protective. A significant age by Work-To-Family conflict interaction revealed that higher Work-To-Family conflict was more strongly associated with increased cardiometabolic risk in younger employees. With regard to sleep duration, high Family-To-Work Conflict was significantly associated with shorter sleep duration. In addition, working long hours and having younger children at home were both independently associated with shorter sleep duration. High Work-To-Family Conflict was associated with longer sleep duration. These results indicate that different dimensions of work-family conflict (i.e., Work-To-Family Conflict and Family-To-Work Conflict) may both pose threats to cardiometabolic risk and sleep duration for employees. This study contributes to the research on work- family conflict suggesting that Work-To-Family and Family-To-Work conflict are associated with specific outcomes. Translating theory and our findings to preventive interventions entails recognition of the dimensionality of work and family dynamics and the need to target specific work and family conditions

Hygiene During Childbirth: An Observational Study to Understand Infection Risk in Healthcare Facilities in Kogi and Ebonyi States, Nigeria.

Background: Infections acquired during labour and delivery are a significant cause of maternal and child morbidity and mortality. Adherence to hand hygiene protocols is a critical component of infection prevention strategies, but few studies have closely examined the hand hygiene of health care providers with sufficient detail to understand infection risks and prioritize prevention strategies. Methods: This observational study was conducted in six healthcare facilities in Nigeria. In each, five women were observed from the onset of labour through to delivery of the placenta. Hand hygiene infection risk was estimated for all procedures requiring aseptic technique compared against adherence to proper hand hygiene protocol and potential recontamination events. Results: Hands were washed with soap and sterile gloves applied with no observed recontamination before only 3% of all observed procedures requiring aseptic technique. There was no significant difference in hygiene compliance between midwives and doctors nor facilities or states. Adherence to proper hygiene protocol was observed more in morning compared to afternoon and night shifts. Conclusions: This study highlights that hand hygiene remains a barrier to delivering high-quality and safe care in health facilities. Improving hygiene practices during labour and delivery will require strategies that extend beyond infrastructure provision