Strain-induced interface reconstruction in epitaxial heterostructures

We investigate in the framework of Landau theory the distortion of the strain fields at the interface of two dissimilar ferroelastic oxides that undergo a structural cubic-to-tetragonal phase transition. Simple analytical solutions are derived for the dilatational and the order parameter strains that are globally valid over the whole of the heterostructure. The solutions reveal that the dilatational strain exhibits compression close to the interface which may in turn affect the electronic properties in that region.Comment: 7 pages, 5 figures, to be published in Physical Review

Nonlinear magnetoinductive transmission lines

Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent capacitance. Extended numerical simulations reveal that power transmission along the array is also possible in other than the linear frequency bands, which are located close to the nonlinear resonances of a single nonlinear RLC circuit. Moreover, the effectiveness of power transmission for driving frequencies in the nonlinear bands is comparable to that in the linear band. Power transmission in the nonlinear bands occurs through the linear modes of the system, and it is closely related to the instability of a mode that is localized at the driven site.Comment: 11 pages, 11 figures, submitted to International Journal of Bifurcation and Chao

Detailed abundances of a large sample of giant stars in M 54 and in the Sagittarius nucleus

Homogeneous abundances of light elements, alpha and Fe-group elements from high-resolution FLAMES spectra are presented for 76 red giant stars in M54, a massive globular cluster (GC) lying in the nucleus of the Sagittarius dwarf galaxy. We also derived detailed abundances for 27 red giants belonging to the Sgr nucleus. Our abundances assess the intrinsic metallicity dispersion (~0.19 dex, rms scatter) of M54, with the bulk of stars peaking at [Fe/H]~-1.6 and a long tail extending to higher metallicities, similar to omega Cen. The spread in these probable nuclear star clusters exceeds those of most GCs: these massive clusters are located in a region intermediate between normal GCs and dwarf galaxies. M54 shows the Na-O anticorrelation, typical signature of GCs, which is instead absent in the Sgr nucleus. The light elements (Mg, Al, Si) participating to the high temperature Mg-Al cycle show that the pattern of (anti)correlations produced by proton-capture reactions in H-burning is clearly different between the most metal-rich and most metal-poor components in the two most massive GCs in the Galaxy, confirming early result based on the Na-O anticorrelation. As in omega Cen, stars affected by most extreme processing, i.e. showing the signature of more massive polluters, are those of the metal-rich component. This can be understood if the burst of star formation giving birth to the metal-rich component was delayed by as much as 10-30 Myr with respect to the metal-poor one. The evolution of these massive GCs can be reconciled in the general scenario for the formation of GCs sketched in Carretta et al.(2010a) taking into account that omega Cen could have already incorporated the surrounding nucleus of its progenitor and lost the rest of the hosting galaxy while the two are still observable as distinct components in M54 and the surrounding field.Comment: 22 pages (3 pages of appendix), 25 figures. Tables 2, 3, 5, 6, and 7 are only available in electronic form at the CDS Accepted for publication on Astronomy and Astrophysic

Improved Color-Temperature Relations and Bolometric Corrections for Cool Stars

We present new grids of colors and bolometric corrections for F-K stars having 4000 K < Teff < 6500 K, 0.0 < log g < 4.5 and -3.0 < [Fe/H] < 0.0. A companion paper extends these calculations into the M giant regime. Colors are tabulated for Johnson U-V and B-V; Cousins V-R and V-I; Johnson-Glass V-K, J-K and H-K; and CIT/CTIO V-K, J-K, H-K and CO. We have developed these color-temperature (CT) relations by convolving synthetic spectra with photometric filter-transmission-profiles. The synthetic spectra have been computed with the SSG spectral synthesis code using MARCS stellar atmosphere models as input. Both of these codes have been improved substantially, especially at low temperatures, through the incorporation of new opacity data. The resulting synthetic colors have been put onto the observational systems by applying color calibrations derived from models and photometry of field stars which have Teffs determined by the infrared-flux method. The color calibrations have zero points and slopes which change most of the original synthetic colors by less than 0.02 mag and 5%, respectively. The adopted Teff scale (Bell & Gustafsson 1989) is confirmed by the extraordinary agreement between the predicted and observed angular diameters of the field stars. We have also derived empirical CT relations from the field-star photometry. Except for the coolest dwarfs (Teff < 5000 K), our calibrated, solar-metallicity model colors are found to match these and other empirical relations quite well. Our calibrated, 4 Gyr, solar-metallicity isochrone also provides a good match to color-magnitude diagrams of M67. We regard this as evidence that our calibrated colors can be applied to many astrophysical problems, including modelling the integrated light of galaxies. (abridged)Comment: To appear in the March 2000 issue of the Astronomical Journal. 72 pages including 16 embedded postscript figures (one page each) and 6 embedded postscript tables (18 pages total

Novel Androgen Receptor Coregulator GRHL2 Exerts Both Oncogenic and Antimetastatic Functions in Prostate Cancer.

Alteration to the expression and activity of androgen receptor (AR) coregulators in prostate cancer is an important mechanism driving disease progression and therapy resistance. Using a novel proteomic technique, we identified a new AR coregulator, the transcription factor Grainyhead-like 2 (GRHL2), and demonstrated its essential role in the oncogenic AR signaling axis. GRHL2 colocalized with AR in prostate tumors and was frequently amplified and upregulated in prostate cancer. Importantly, GRHL2 maintained AR expression in multiple prostate cancer model systems, was required for cell proliferation, enhanced AR's transcriptional activity, and colocated with AR at specific sites on chromatin to regulate genes relevant to disease progression. GRHL2 is itself an AR-regulated gene, creating a positive feedback loop between the two factors. The link between GRHL2 and AR also applied to constitutively active truncated AR variants (ARV), as GRHL2 interacted with and regulated ARVs and vice versa. These oncogenic functions of GRHL2 were counterbalanced by its ability to suppress epithelial-mesenchymal transition and cell invasion. Mechanistic evidence suggested that AR assisted GRHL2 in maintaining the epithelial phenotype. In summary, this study has identified a new AR coregulator with a multifaceted role in prostate cancer, functioning as an enhancer of the oncogenic AR signaling pathway but also as a suppressor of metastasis-related phenotypes. Cancer Res; 77(13); 3417-30. ©2017 AACR

Dwarf Elliptical Galaxies

Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than $M_B = -16$, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how well currently available data can constrain 1) models for the formation of dE's, 2) the physical and evolutionary connections between different types of galaxies (nucleated and nonnucleated dE's, compact E's, irregulars, and blue compact dwarfs) that overlap in the same portion of the mass-spectrum of galaxies, 3) the contribution of dE's to the galaxy luminosity functions in clusters and the field, 4) the star-forming histories of dE's and their possible contribution to faint galaxy counts, and 5) the clustering properties of dE's. In addressing these issues, we highlight the extent to which selection effects temper these constraints, and outline areas where new data would be particularly valuable.Comment: 63p, uuencoded compressed postscript, 2/8 figs included, A&A Review in press, request paper copies from [email protected], STScI 86

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Current phase relation from graphs and diagrams and application to thick ferromagnetic Josephson junctions

In this work we present a method of representing terms in the current-phase-relation of a ballistic Josephson junction by combinations of diagrams, used in previous work to represent an equivalent of the matching condition determinant of the junction. This is accomplished by the expansion of the logarithm of this determinant in Taylor series and keeping track of surviving terms, i.e. terms that do not annihilate each other. The types of the surviving terms are represented by connected graphs, whose points represent diagrammatic terms of the determinant expansion. Then the theory is applied to obtain approximations of the current-phase relation of relatively thick ballistic ferromagnetic Josephson junctions with non-collinear magnetizations. This demonstrates the versatility of the method in developing approximations schemes and providing physical insight into the nature of contributions to the supercurrent from the available particle excitations in the junction. We also discuss the strong second harmonic contribution to the supercurrent in junctions with three mutually orthogonal magnetization vectors and a weak intermediate ferromagnet. © 2018 IOP Publishing Ltd

Resonant effects in ballistic Josephson junctions

74.50.+r Tunneling phenomena; point contacts, weak links, Josephson effects, 73.23.-b Electronic transport in mesoscopic systems,