Measuring the mass of the central black hole in the bulgeless galaxy ngc 4395 from gas dynamical modeling

NGC 4395 is a bulgeless spiral galaxy, harboring one of the nearest known type 1 Seyfert nuclei. Although there is no consensus on the mass of its central engine, several estimates suggest it is one of the lightest massive black holes (MBHs) known. We present the first direct dynamical measurement of the mass of this MBH from a combination of two-dimensional gas kinematic data, obtained with the adaptive optics assisted near-infrared integral field spectrograph Gemini/NIFS and high-resolution multiband photometric data from Hubble Space Telescope's Wide Field Camera 3. We use the photometric data to model the shape and stellar mass-to-light ratio of the nuclear star cluster (NSC). From the Gemini/NIFS observations, we derive the kinematics of warm molecular hydrogen gas as traced by emission through the H2 1–0 S(1) transition. These kinematics show a clear rotational signal, with a position angle orthogonal to NGC 4395's radio jet. Our best-fitting tilted ring models of the kinematics of the molecular hydrogen gas contain a black hole with mass M={4}-3+8× {10}5 M⊙ (3σ uncertainties) embedded in an NSC of mass M=2× {10}6 M⊙. Our black hole mass measurement is in excellent agreement with the reverberation mapping mass estimate of Peterson et al. but shows some tension with other mass measurement methods based on accretion signals

A mathematical framework for critical transitions: normal forms, variance and applications

Critical transitions occur in a wide variety of applications including mathematical biology, climate change, human physiology and economics. Therefore it is highly desirable to find early-warning signs. We show that it is possible to classify critical transitions by using bifurcation theory and normal forms in the singular limit. Based on this elementary classification, we analyze stochastic fluctuations and calculate scaling laws of the variance of stochastic sample paths near critical transitions for fast subsystem bifurcations up to codimension two. The theory is applied to several models: the Stommel-Cessi box model for the thermohaline circulation from geoscience, an epidemic-spreading model on an adaptive network, an activator-inhibitor switch from systems biology, a predator-prey system from ecology and to the Euler buckling problem from classical mechanics. For the Stommel-Cessi model we compare different detrending techniques to calculate early-warning signs. In the epidemics model we show that link densities could be better variables for prediction than population densities. The activator-inhibitor switch demonstrates effects in three time-scale systems and points out that excitable cells and molecular units have information for subthreshold prediction. In the predator-prey model explosive population growth near a codimension two bifurcation is investigated and we show that early-warnings from normal forms can be misleading in this context. In the biomechanical model we demonstrate that early-warning signs for buckling depend crucially on the control strategy near the instability which illustrates the effect of multiplicative noise.Comment: minor corrections to previous versio

Mr. Wicksell and the Global Economy: What Drives Real Interest Rates?

We use a Bayesian dynamic latent factor model to extract world, regional and country factors of real interest rate series for 22 OECD economies. We find that the world factor plays a privileged role in explaining the variance of real rates for most countries in the sample, and accounts for the steady decrease in interest rates in the last decades. Moreover, the relative contribution of the world factor is rising over time. We also find relevant differences between the group of countries that follow fixed exchange rate strategies and those with flexible regimes

Barriers to the acceptance of electronic medical records by physicians from systematic review to taxonomy and interventions

<p>Abstract</p> <p>Background</p> <p>The main objective of this research is to identify, categorize, and analyze barriers perceived by physicians to the adoption of Electronic Medical Records (EMRs) in order to provide implementers with beneficial intervention options.</p> <p>Methods</p> <p>A systematic literature review, based on research papers from 1998 to 2009, concerning barriers to the acceptance of EMRs by physicians was conducted. Four databases, "Science", "EBSCO", "PubMed" and "The Cochrane Library", were used in the literature search. Studies were included in the analysis if they reported on physicians' perceived barriers to implementing and using electronic medical records. Electronic medical records are defined as computerized medical information systems that collect, store and display patient information.</p> <p>Results</p> <p>The study includes twenty-two articles that have considered barriers to EMR as perceived by physicians. Eight main categories of barriers, including a total of 31 sub-categories, were identified. These eight categories are: A) Financial, B) Technical, C) Time, D) Psychological, E) Social, F) Legal, G) Organizational, and H) Change Process. All these categories are interrelated with each other. In particular, Categories G (Organizational) and H (Change Process) seem to be mediating factors on other barriers. By adopting a change management perspective, we develop some barrier-related interventions that could overcome the identified barriers.</p> <p>Conclusions</p> <p>Despite the positive effects of EMR usage in medical practices, the adoption rate of such systems is still low and meets resistance from physicians. This systematic review reveals that physicians may face a range of barriers when they approach EMR implementation. We conclude that the process of EMR implementation should be treated as a change project, and led by implementers or change managers, in medical practices. The quality of change management plays an important role in the success of EMR implementation. The barriers and suggested interventions highlighted in this study are intended to act as a reference for implementers of Electronic Medical Records. A careful diagnosis of the specific situation is required before relevant interventions can be determined.</p

One year outcomes of a mentoring scheme for female academics: a pilot study at the Institute of Psychiatry, King's College London

<p>Abstract</p> <p>Background</p> <p>The professional development of under-represented faculty may be enhanced by mentorship, but we understand very little about the mechanisms by which mentoring brings about change. Our study posed the research question, what are the mechanisms by which mentoring may support professional development in under-represented groups?</p> <p>The study aims to: (i) to pilot a mentoring scheme for female academics; (ii) to compare various health-related and attitudinal measures in mentees at baseline, 6 months, and 1 year into the mentoring relationship and, (iii) to compare pre-mentoring expectations to outcomes at 6 months and 1 year follow-up for mentees and mentors.</p> <p>Methods</p> <p>Female academic mentees were matched 1:1 or 2:1 with more senior academic mentors. Online surveys were conducted to compare health-related and attitudinal measures and expectations of mentoring at baseline with outcomes at 6 months and 1 year using paired t-tests and McNemar's test for matched cohort data.</p> <p>Results</p> <p>N = 46 mentoring pairs, 44 (96%) mentees completed the pre-mentoring survey, 37 (80%) at 6 months and 30 (65%) at 1 year. Job-related well-being (anxiety-contentment), self-esteem and self-efficacy all improved significantly and work-family conflict diminished at 1 year. Highest expectations were career progression (39; 89%), increased confidence (38; 87%), development of networking skills (33; 75%), better time-management (29; 66%) and better work-life balance (28; 64%). For mentees, expectations at baseline were higher than perceived achievements at 6 months or 1 year follow-up.</p> <p>For mentors (N = 39), 36 (92%) completed the pre-mentoring survey, 32 (82%) at 6 months and 28 (72%) at 1 year. Mentors' highest expectations were of satisfaction in seeing people progress (26; 69%), seeing junior staff develop and grow (19; 53%), helping solve problems (18; 50%), helping women advance their careers (18; 50%) and helping remove career obstacles (13; 36%). Overall, gains at 6 months and 1 year exceeded pre-mentoring expectations.</p> <p>Conclusions</p> <p>This uncontrolled pilot study suggests that mentoring can improve aspects of job-related well-being, self-esteem and self-efficacy over 6 months, with further improvements seen after 1 year for female academics. Work-family conflict can also diminish. Despite these gains, mentees' prior expectations were shown to be unrealistically high, but mentors' expectations were exceeded.</p

An X-Ray-Selected Sample of Candidate Black Holes in Dwarf Galaxies

We present a sample of hard X-ray-selected candidate black holes (BHs) in 19 dwarf galaxies. BH candidates are identified by cross-matching a parent sample of ~44,000 local dwarf galaxies (M* = 3 × 10 9 M☉, z < 0.055) with the Chandra Source Catalog and subsequently analyzing the original X-ray data products for matched sources. Of the 19 dwarf galaxies in our sample, eight have X-ray detections reported here for the first time. We find a total of 43 point-like hard X-ray sources with individual luminosities L2-10 keV ~ 10 37 - 10 40 erg s-1. Hard X-ray luminosities in this range can be attained by stellar-mass X-ray binaries (XRBs) and by massive BHs accreting at low Eddington ratio. We place an upper limit of 53% (10/19) on the fraction of galaxies in our sample hosting a detectable hard X-ray source consistent with the optical nucleus, although the galaxy center is poorly defined in many of our objects. We also find that 42% (8/19) of the galaxies in our sample exhibit statistically significant enhanced hard X-ray emission relative to the expected galaxy-wide contribution from low-mass and high-mass XRBs, based on the [data] star formation rate relation defined by more massive and luminous systems. For the majority of these X-ray-enhanced dwarf galaxies, the excess emission is consistent with (but not necessarily due to) a nuclear X-ray source. Follow-up observations are necessary to distinguish between stellar-mass XRBs and active galactic nuclei powered by more massive BHs. In any case, our results support the notion that X-ray-emitting BHs in low-mass dwarf galaxies may have had an appreciable impact on reionization in the early universe

Exploring dietitians' salient beliefs about shared decision-making behaviors

<p>Abstract</p> <p>Background</p> <p>Shared decision making (SDM), a process by which health professionals and patients go through the decision-making process together to agree on treatment, is a promising strategy for promoting diet-related decisions that are informed and value based and to which patients adhere well. The objective of the present study was to identify dietitians' salient beliefs regarding their exercise of two behaviors during the clinical encounter, both of which have been deemed essential for SDM to take place: (1) presenting patients with all dietary treatment options for a given health condition and (2) helping patients clarify their values and preferences regarding the options.</p> <p>Methods</p> <p>Twenty-one dietitians were allocated to four focus groups. Facilitators conducted the focus groups using a semistructured interview guide based on the Theory of Planned Behavior. Discussions were audiotaped, transcribed verbatim, coded, and analyzed with NVivo8 (QSR International, Cambridge, MA) software.</p> <p>Results</p> <p>Most participants stated that better patient adherence to treatment was an advantage of adopting the two SDM behaviors. Dietitians identified patients, physicians, and the multidisciplinary team as normative referents who would approve or disapprove of their adoption of the SDM behaviors. The most often reported barriers and facilitators for the behaviors concerned patients' characteristics, patients' clinical situation, and time.</p> <p>Conclusions</p> <p>The implementation of SDM in nutrition clinical practice can be guided by addressing dietitians' salient beliefs. Identifying these beliefs also provides the theoretical framework needed for developing a quantitative survey questionnaire to further study the determinants of dietitians' adoption of SDM behaviors.</p

The X-ray properties of million solar mass black holes

We present new Chandra X-ray observations of seven low-mass black holes (~1e6 Msun) accreting at low Eddington ratios between -2.0<log L/Ledd<-1.5. We compare the X-ray properties of these seven low-mass active galactic nuclei (AGN) to a total of 73 other low-mass AGN in the literature with published Chandra observations (with Eddington ratios extending from -2.0<log L/Ledd<-0.1). We do not find any statistical differences between low- and high-Eddington ratio low-mass AGN in the distributions of their X-ray to ultraviolet luminosity ratios (aox), or in their X-ray spectral shapes. Furthermore, the aox distribution of low-L/Ledd AGN displays an X-ray weak tail that is also observed within high-L/Ledd objects. Our results indicate that between -2<log L/Ledd<-0.1, there is no systematic change in the structure of the accretion flow for active galaxies hosting 1e6 Msun black holes. We examine the accuracy of current bolometric luminosity estimates for our low-L/Ledd objects with new Chandra observations, and it is plausible that their Eddington ratios could be underestimated by up to an order of magnitude. If so, then in analogy with weak emission line quasars, we suggest that accretion from a geometrically thick, radiatively inefficient `slim disk' could explain their diverse properties in aox. Alternatively, if current Eddington ratios are in fact correct (or overestimated), then the X-ray weak tail would imply that there is diversity in disk/corona couplings among individual low-mass objects. Finally, we conclude by noting that the aox distribution for low-mass black holes may have favorable consequences for the epoch of cosmic reionization being driven by AGN.Comment: 14 pages, 6 figures, 6 tables. Accepted for publication in Ap