Binary-black-hole initial data with nearly-extremal spins

There is a significant possibility that astrophysical black holes with nearly-extremal spins exist. Numerical simulations of such systems require suitable initial data. In this paper, we examine three methods of constructing binary-black-hole initial data, focusing on their ability to generate black holes with nearly-extremal spins: (i) Bowen-York initial data, including standard puncture data (based on conformal flatness and Bowen-York extrinsic curvature), (ii) standard quasi-equilibrium initial data (based on the extended-conformal-thin-sandwich equations, conformal flatness, and maximal slicing), and (iii) quasi-equilibrium data based on the superposition of Kerr-Schild metrics. We find that the two conformally-flat methods (i) and (ii) perform similarly, with spins up to about 0.99 obtainable at the initial time. However, in an evolution, we expect the spin to quickly relax to a significantly smaller value around 0.93 as the initial geometry relaxes. For quasi-equilibrium superposed Kerr-Schild (SKS) data [method (iii)], we construct initial data with \emph{initial} spins as large as 0.9997. We evolve SKS data sets with spins of 0.93 and 0.97 and find that the spin drops by only a few parts in 10^4 during the initial relaxation; therefore, we expect that SKS initial data will allow evolutions of binary black holes with relaxed spins above 0.99. [Abstract abbreviated; full abstract also mentions several secondary results.

Aging and Health: An Examination of Differences between Older Aboriginal and non-Aboriginal People

The Aboriginal population in Canada, much younger than the general population, has experienced a trend towards aging over the past decade. Using data from the 2001 Aboriginal Peoples Survey (APS) and the 2000/2001 Canadian Community Health Survey (CCHS), this article examines differences in health status and the determinants of health and health care use between the 55-and-older Aboriginal population and non-Aboriginal population. The results show that the older Aboriginal population is unhealthier than the non-Aboriginal population across all age groups; differences in health status, however, appear to converge as age increases. Among those aged 55 to 64, 7 per cent of the Aboriginal population report three or more chronic conditions compared with 2 per cent of the non-Aboriginal population. Yet, among those aged 75 and older, 51 per cent of the Aboriginal population report three or more chronic conditions in comparison with 23 per cent of the non-Aboriginal population.Aboriginal people, health status, health care use

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes II. Stationary Black Holes

When one splits spacetime into space plus time, the Weyl curvature tensor (which equals the Riemann tensor in vacuum) splits into two spatial, symmetric, traceless tensors: the tidal field $E$, which produces tidal forces, and the frame-drag field $B$, which produces differential frame dragging. In recent papers, we and colleagues have introduced ways to visualize these two fields: tidal tendex lines (integral curves of the three eigenvector fields of $E$) and their tendicities (eigenvalues of these eigenvector fields); and the corresponding entities for the frame-drag field: frame-drag vortex lines and their vorticities. These entities fully characterize the vacuum Riemann tensor. In this paper, we compute and depict the tendex and vortex lines, and their tendicities and vorticities, outside the horizons of stationary (Schwarzschild and Kerr) black holes; and we introduce and depict the black holes' horizon tendicity and vorticity (the normal-normal components of $E$ and $B$ on the horizon). For Schwarzschild and Kerr black holes, the horizon tendicity is proportional to the horizon's intrinsic scalar curvature, and the horizon vorticity is proportional to an extrinsic scalar curvature. We show that, for horizon-penetrating time slices, all these entities ($E$, $B$, the tendex lines and vortex lines, the lines' tendicities and vorticities, and the horizon tendicities and vorticities) are affected only weakly by changes of slicing and changes of spatial coordinates, within those slicing and coordinate choices that are commonly used for black holes. [Abstract is abbreviated.]Comment: 19 pages, 7 figures, v2: Changed to reflect published version (changes made to color scales in Figs 5, 6, and 7 for consistent conventions). v3: Fixed Ref

Using Expert Panels to Elicit Potential Indicators and Predictors of EBPH in Local Health Departments

Research Objective: To identify appropriate indicators of local health department (LHD) use of EBPH strategies and factors that influence their use. Data Sets and Sources: Transcripts of interviews with 12 members of an expert panel representing researchers and practitioners working in PHSSR and Evidence-Based Public Health. Study Design: Participants responded to a series of questions regarding: their definition of EBPH; ways to identify and assess the use of EBPH strategies; and perceived barriers/enablers to the use of these strategies at the state and local levels. Analysis: Content analysis performed using QSR NVivo V. 9. Data matrices were created highlighting each participant\u27s comments related to EBPH strategies and factors influencing the use of EBPH strategies (including state level, local health department level and community level factors). Strategies were categorized based on definitions of EBPH used by participants. Principal Findings: Two basic definitions of EBPH emerged, with one reflecting the use of data in decision-making processes, and the other reflecting the adoption of scientifically tested interventions. Factors at the state, local health department and community levels that influenced EBPH depended, in part, on the definition of EBPH used by participants. Conclusion: LHD use of EBPH was influenced by health officer training and leadership, characteristics of the workforce, and training and technical assistance provided at the state and local levels. Familiarity with resources on tested interventions was key for one definition of EBPH. Community partnerships and competency in using data were key for others. Implications for the Field of PHSSR: PHSSR and practice related to EBPH need to include precise definitions of terms to have meaningful discussions regarding how to encourage the use of EBPH strategies

Predictors of Evidence-Based Decision Making and Population Health Practice in LHDs

Research Objective: To identify the frequency with which LHDs carry out Evidence-Based Decision Making (EBDM) and population health strategies in LHDs and state-, LHD-, and community-levels predictors of LHDs\u27 use of these strategies. Data Sets and Sources: Harmonized PHSSR dataset consisting of 2010 NACCHO Profile of Local Health Departments Survey, Module 2 respondents, 2010 ASTHO Profile of State Health Departments, US Census data, and Area Resource File data. Study Design: The study used multivariate analysis to identify predictors of EBDM and population health. We identified items in the 2010 NACCHO Profile Survey representing EBDM and population health strategies and constructed two composite dependent variables. Based on the PHSSR literature, we identified potential predictors at the state-, LHD-, and community levels. Analysis: Using descriptive analyses, we determined the frequency with which LHDs carry out EBDM strategies and population health strategies. Hierarchical linear modeling (HLM) was used to identify factors that best predict LHDs\u27 use of EBDM and population health strategies. Principal Findings: Fourteen percent of LHDs engaged in six or seven (out of seven) EBDM strategies; and 15% used six or more (out of 10) population health strategies. Hierarchical linear modeling results will identify modifiable state health department, LHD, and community context predictors of LHDs\u27 use of these strategies. Conclusion: Based on data from the NACCHO Profile Survey, LHDs vary greatly in the extent to which they focus on EBDM and population health practice. The paths that lead LHDs to focus on EBDM and population health practice are complex and diverse. Implications For The Field Of PHSSR: For PHSSR research, more precise data definitions and questions are needed in national surveys such as the NACCHO and ASTHO surveys. More research is needed to understand how LHDs use EBDM strategies (and which ones they use) as well as how they make decisions about focusing on population health practice

LHDs Increase Their Use of EBDM Practices From 2010 to 2013

Background: An evidence-based approach is needed to effectively address the gap between population health goals in the United States and current morbidity and mortality rates. Recently, the authors developed an index to allow researchers to assess the frequency of evidence-based decision making (EBDM) practice in LHDs. The first descriptive analysis was conducted with data from the NACCHO 2010 Profile Study of Local Health Departments (LHDs). The current research was designed to assess changes in the percentage of LHDs using EBDM practices from 2010 to 2013. Research Objective: To identify changes in the frequency with which LHDs carried out EBDM practices from 2010 to 2013. Data sets and sources: 2010 NACCHO Profile of LHDs Survey, 2013 NACCHO Profile of LHDs Survey. The NACCHO Profile Surveys are conducted every 2-3 years. All LHDs in the country are invited to respond. Study Design: Cross-sectional survey Analysis: The research reported here used an index of EBDM practices previously developed by the authors. Descriptive analysis was used to identify the frequency with which LHDs used each EBDM practice comprising the index and the frequency of the total number of practices they used in both 2010 and 2013. Principal Findings: Overall, the percentage of LHDs using EBDM practices increased from 2010 to 2013. Specifically, in 2010, forty-five percent of LHDs used three EBDM practices or fewer; 41.5% used four or five EBDM practices; and 13.5% used six or seven practices. In 2013, thirty-seven percent of LHDs used three EBDM practices or fewer; 39% used four or five practices; and 23.7% used six or seven practices. The overall increase in numbers of EBDM practices used by LHDs was largely driven by increases in percentages of LHDs that use the County Health Rankings (37.8% to 66.5%) and that use The Guide to Community Preventive Services (26% to 41.2%)(Table 1). Implications for PH Policy and Practice: The results reveal that there is an increase in the use of EBDM practices in LHDs from 2010 to 2013. More research is needed to understand details of how LHDs implement EBDM strategies and use them to innovate the practice of public health

Frame-Dragging Vortexes and Tidal Tendexes Attached to Colliding Black Holes: Visualizing the Curvature of Spacetime

When one splits spacetime into space plus time, the spacetime curvature (Weyl tensor) gets split into an "electric" part E_{jk} that describes tidal gravity and a "magnetic" part B_{jk} that describes differential dragging of inertial frames. We introduce tools for visualizing B_{jk} (frame-drag vortex lines, their vorticity, and vortexes) and E_{jk} (tidal tendex lines, their tendicity, and tendexes), and also visualizations of a black-hole horizon's (scalar) vorticity and tendicity. We use these tools to elucidate the nonlinear dynamics of curved spacetime in merging black-hole binaries.Comment: 4 pages, 5 figure

Visualizing Spacetime Curvature via Frame-Drag Vortexes and Tidal Tendexes III. Quasinormal Pulsations of Schwarzschild and Kerr Black Holes

In recent papers, we and colleagues have introduced a way to visualize the full vacuum Riemann curvature tensor using frame-drag vortex lines and their vorticities, and tidal tendex lines and their tendicities. We have also introduced the concepts of horizon vortexes and tendexes and 3-D vortexes and tendexes (regions where vorticities or tendicities are large). Using these concepts, we discover a number of previously unknown features of quasinormal modes of Schwarzschild and Kerr black holes. These modes can be classified by mode indexes (n,l,m), and parity, which can be electric [(-1)^l] or magnetic [(-1)^(l+1)]. Among our discoveries are these: (i) There is a near duality between modes of the same (n,l,m): a duality in which the tendex and vortex structures of electric-parity modes are interchanged with the vortex and tendex structures (respectively) of magnetic-parity modes. (ii) This near duality is perfect for the modes' complex eigenfrequencies (which are well known to be identical) and perfect on the horizon; it is slightly broken in the equatorial plane of a non-spinning hole, and the breaking becomes greater out of the equatorial plane, and greater as the hole is spun up; but even out of the plane for fast-spinning holes, the duality is surprisingly good. (iii) Electric-parity modes can be regarded as generated by 3-D tendexes that stick radially out of the horizon. As these "longitudinal," near-zone tendexes rotate or oscillate, they generate longitudinal-transverse near-zone vortexes and tendexes, and outgoing and ingoing gravitational waves. The ingoing waves act back on the longitudinal tendexes, driving them to slide off the horizon, which results in decay of the mode's strength. (iv) By duality, magnetic-parity modes are driven in this same manner by longitudinal, near-zone vortexes that stick out of the horizon. [Abstract abridged.]Comment: 53 pages with an overview of major results in the first 11 pages, 26 figures. v2: Very minor changes to reflect published version. v3: Fixed Ref

Framing Photovoice Using a Social---Ecological Logic Model as a Guide.

Photovoice is a community-based participatory action research method designed to uncover the root causes of community problems and to collectively address them. Individual change and empowerment are desired outcomes of the photovoice process, but more importantly, the process seeks to engage groups and whole communities to foster positive systems change. This article presents a logic model informed by the social-ecological model of health to guide photovoice planners and participants in planning activities that produce individual-and community-level change. The model presented here should help planners and participants plan, implement, and evaluate other photovoice efforts and provide them a visual guide to ensure that all parties are on the same conceptual page and increase the intentionality of their efforts