How Useful Are Estimated DSGE Model Forecasts for Central Bankers?

bank, banker, DSGE, forecast, macroeconomic

The role of spin-orbit coupling in topologically protected interface states in Dirac materials

We highlight the fact that two-dimensional materials with Dirac-like low energy band structures and spin-orbit coupling will produce linearly dispersing topologically protected Jackiw-Rebbi modes at interfaces where the Dirac mass changes sign. These modes may support persistent spin or valley currents parallel to the interface, and the exact arrangement of such topologically protected currents depends crucially on the details of the spin-orbit coupling in the material. As examples, we discuss buckled two-dimensional hexagonal lattices such as silicene or germanene, and transition metal dichalcogenides such as MoS$_2$.Comment: 8 pages, 2 figure

“Being in Balance”: Self-Management Experiences Among Young Women with Type 1 Diabetes

Women possess characteristics and experiences unique and different from men. Biological processes such as puberty, menstruation, motherhood and menopause may present challenges to self-management for individuals living with type 1 (T1) diabetes mellitus. In this study, descriptive phenomenology was used to uncover the self-management experiences of nine women aged 22- 30 years living with T1 diabetes. Data collection and analysis occurred simultaneously and followed the methodical structure of van Manen (1997). Study findings revealed five themes: 1) elusiveness of control; 2) dualism of technology; 3) forecasting and maintaining routines; 4) dealing with the “ups and downs”; and, 5) interfacing with the health care team. The essence of the experience for participants revolved around trying to achieve a state of “being in balance.” For these young women, self-management encompassed a desire and need to be in balance with their life and blood sugar levels

Group-cluster merging and the formation of starburst galaxies

A significant fraction of clusters of galaxies are observed to have substructure, which implies that merging between clusters and subclusters is a rather common physical process of cluster formation. It still remains unclear how cluster merging affects the evolution of cluster member galaxies. We report the results of numerical simulations, which show the dynamical evolution of a gas-rich late-type spiral in a merger between a small group of galaxies and a cluster. The simulations demonstrate that time-dependent tidal gravitational field of the merging excites non-axisymmetric structure of the galaxy, subsequently drives efficient transfer of gas to the central region, and finally triggers a secondary starburst. This result provides not only a new mechanism of starbursts but also a close physical relationship between the emergence of starburst galaxies and the formation of substructure in clusters. We accordingly interpret post-starburst galaxies located near substructure of the Coma cluster as one observational example indicating the global tidal effects of group-cluster merging. Our numerical results furthermore suggest a causal link between the observed excess of blue galaxies in distant clusters and cluster virialization process through hierarchical merging of subclusters.Comment: 5 pages 3 color figures, ApJL in pres

The First Detailed X-ray Observations of High-Redshift, Optically-Selected Clusters: XMM-Newton Results for Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90

We present the first detailed X-ray observations of optically-selected clusters at high redshift. Two clusters, Cl 1324+3011 at z = 0.76 and Cl 1604+4304 at z = 0.90, were observed with XMM-Newton. The optical center of each cluster is coincident with an extended X-ray source whose emission is detected out to a radius of 0.5 Mpc. The emission from each cluster appears reasonably circular, with some indication of asymmetries and more complex morphologies. Similarly to other optically-selected clusters at redshifts of z > 0.4, both clusters are modest X-ray emitters with bolometric luminosities of only Lx = 1.4 - 2.0 x 10^(44) erg/s. We measure gas temperatures of T = 2.88 (+0.71/-0.49) keV for Cl 1324+3011 and 2.51 (+1.05/-0.69) keV for Cl 1604+4304. The X-ray properties of both clusters are consistent with the high-redshift Lx-T relation measured from X-ray-selected samples at z > 0.5. However, based on the local relations, their X-ray luminosities and temperatures are low for their measured velocity dispersions (sigma). The clusters are cooler by a factor of 2 - 9 compared to the local sigma-T relation. We briefly discuss the possible explanations for these results.Comment: 14 pages, 4 figures; accepted for publication in Astrophysical Journal Letters; version with full resolution figures available at http://bubba.ucdavis.edu/~lubin/xmm.pd

Detection of Bulk Motions in the ICM of the Centaurus Cluster

Several recent numerical simulations of off-center cluster mergers predict that significant angular momentum with associated velocities of a few x 10^{3} km/s can be imparted to the resulting cluster. Such gas bulk velocities can be detected by the Doppler shift of X-ray spectral lines with ASCA spectrometers. Using two ASCA observations of the Centaurus cluster, we produced a velocity map for the gas in the cluster's central regions. We also detected radial and azimuthal gradients in temperature and metal abundance distributions, which seem to be associated with the infalling sub-group centered at NGC 4709 (Cen 45). More importantly, we found a significant (>99.8% confidence level) velocity gradient along a line near-perpendicular to the direction of the incoming sub-group and with a maximum velocity difference of ~3.4+-1.1 x 10^{3} km/s. It is unlikely (P < 0.002) that the observed velocity gradient is generated by gain fluctuations across the detectors. While the observed azimuthal temperature and abundance variations can be attributed to the interaction with Cen 45, we argue that the intracluster gas velocity gradient is more likely due to a previous off-center merging event in the main body of the Centaurus cluster.Comment: 13 pages in emulateapj5 style, 8 postscript figures; Accepted by ApJ; Revised version with minor change

A Very Hot, High Redshift Cluster of Galaxies: More Trouble for Omega_0 = 1

We have observed the most distant (z=0.829) cluster of galaxies in the Einstein Extended Medium Sensitivity Survey, with the ASCA and ROSAT satellites. We find an X-ray temperature of 12.3 +3.1/-2.2 keV for this cluster, and the ROSAT map reveals significant substructure. The high temperature of MS1054-0321 is consistent with both its approximate velocity dispersion, based on the redshifts of 12 cluster members we have obtained at the Keck and the Canada-France-Hawaii telescopes, and with its weak lensing signature. The X-ray temperature of this cluster implies a virial mass ~ 7.4 x 10^14 h^-1 solar masses, if the mean matter density in the universe equals the critical value, or larger if Omega_0 < 1. Finding such a hot, massive cluster in the EMSS is extremely improbable if clusters grew from Gaussian perturbations in an Omega_0 = 1 universe. Combining the assumptions that Omega_0 = 1 and that the intial perturbations were Gaussian with the observed X-ray temperature function at low redshift, we show that the probability of this cluster occurring in the volume sampled by the EMSS is less than a few times 10^{-5}. Nor is MS1054-0321 the only hot cluster at high redshift; the only two other $z > 0.5$ EMSS clusters already observed with ASCA also have temperatures exceeding 8 keV. Assuming again that the initial perturbations were Gaussian and Omega_0 = 1, we find that each one is improbable at the < 10^{-2} level. These observations, along with the fact that these luminosities and temperatures of the high-$z$ clusters all agree with the low-z L_X-T_X relation, argue strongly that Omega_0 < 1. Otherwise, the initial perturbations must be non-Gaussian, if these clusters' temperatures do indeed reflect their gravitational potentials.Comment: 20 pages, 4 figures, To appear in 1 Aug 1998 ApJ (heavily revised version of original preprint

Empirical Impact Evaluation of the WHO Global Code of Practice on the International Recruitment of Health Personnel in Australia, Canada, UK and USA

Background: The active recruitment of health workers from developing countries to developed countries has become a major threat to global health. In an effort to manage this migration, the 63rd World Health Assembly adopted the World Health Organization (WHO) Global Code of Practice on the International Recruitment of Health Personnel in May 2010. While the Code has been lauded as the first globally-applicable regulatory framework for health worker recruitment, its impact has yet to be evaluated. We offer the first empirical evaluation of the Code’s impact on national and sub-national actors in Australia, Canada, United Kingdom and United States of America, which are the English-speaking developed countries with the greatest number of migrant health workers. Methods: 42 key informants from across government, civil society and private sectors were surveyed to measure their awareness of the Code, knowledge of specific changes resulting from it, overall opinion on the effectiveness of non-binding codes, and suggestions to improve this Code’s implementation. Results: 60% of respondents believed their colleagues were not aware of the Code, and 93% reported that no specific changes had been observed in their work as a result of the Code. 86% reported that the Code has not had any meaningful impact on policies, practices or regulations in their countries. Conclusions: This suggests a gap between awareness of the Code among stakeholders at global forums and the awareness and behaviour of national and sub-national actors. Advocacy and technical guidance for implementing the Code are needed to improve its impact on national decision-makers

The X-ray Luminosity Function of Bright Clusters in the Local Universe

We present the X-ray luminosity function (XLF) for clusters of galaxies derived from the RASS1 Bright Sample. The sample, selected from the ROSAT All-Sky Survey in a region of 2.5 sr within the southern Galactic cap, contains 130 clusters with flux limits in the range ~ 3-4 x 10^-12 ergs/cm^2/s in the 0.5-2.0 keV band. A maximum-likelihood fit with a Schechter function of the XLF over the entire range of luminosities (0.045 - 28. x 10^44 ergs/s), gives alpha = 1.52 +/- 0.11, L_* = 3.80 +0.70 -0.55 x 10^44 ergs/s, and A = 5.07 +/- 0.45 x 10^-7 Mpc^-3 (10^44 ergs/s)^(\alpha-1). We investigate possible evolutionary effects within the sample, out to our redshift limit (z ~ 0.3), finding no evidence for evolution. Our results are in good agreement with other local estimates of the XLF, implying that this statistic for the local universe is now well determined. Comparison with XLFs for distant clusters (0.3 < z < 0.6), shows that no evolution is present for L_X < 10^{44} ergs/s. However, we detect differences at the 3 sigma level, between our local XLF and the distant one estimated by Henry et al. for the EMSS sample. This difference is still present when considering the EMSS sample revised by Nichol et al.Comment: 13 pages with 3 figures included, LaTex, aaspp4.sty and epsf.sty, accepted for publication in ApJ Letters, only minor changes, added reference