The Proper Motion of PSR J0205+6449 in 3C 58

We report on sensitive phase-referenced and gated 1.4-GHz VLBI radio observations of the pulsar PSR J0205+6449 in the young pulsar-wind nebula 3C 58, made in 2007 and 2010. We employed a novel technique where the ~105-m Green Bank telescope is used simultaneously to obtain single-dish data used to determine the pulsar's period as well as to obtain the VLBI data, allowing the VLBI correlation to be gated synchronously with the pulse to increase the signal-to-noise. The high timing noise of this young pulsar precludes the determination of the proper motion from the pulsar timing. We derive the position of the pulsar accurate at the milliarcsecond level, which is consistent with a re-determined position from the Chandra X-ray observations. We reject the original tentative optical identification of the pulsar by Shearer and Neustroev (2008), but rather identify a different optical counterpart on their images, with R-band magnitude ~24. We also determine an accurate proper motion for PSR J0205+6449 of (2.3 +- 0.3) mas/yr, corresponding to a projected velocity of only (35 +- 6) km/s for a distance of 3.2 kpc, at p.a. -38 deg. This projected velocity is quite low compared to the velocity dispersion of known pulsars of ~200 km/s. Our measured proper motion does not suggest any particular kinematic age for the pulsar.Comment: 10 pages, 7 figures; accepted for publication in MNRA

Spin reorientation in Na-doped BaFe2_2As2_2 studied by neutron diffraction

We have studied the magnetic ordering in Na doped BaFe$_2$As$_2$ by unpolarized and polarized neutron diffraction using single crystals. Unlike previously studied FeAs-based compounds that magnetically order, Ba$_{1-x}$Na$_x$Fe$_2$As$_2$ exhibits two successive magnetic transitions: For x=0.35 upon cooling magnetic order occurs at $\sim$70\ K with in-plane magnetic moments being arranged as in pure or Ni, Co and K-doped BaFe$_2$As$_2$ samples. At a temperature of $\sim$46\ K a second phase transition occurs, which the single-crystal neutron diffraction experiments can unambiguously identify as a spin reorientation. At low temperatures, the ordered magnetic moments in Ba$_{0.65}$Na$_{0.35}$Fe$_2$As$_2$ point along the $c$ direction. Magnetic correlations in these materials cannot be considered as Ising like, and spin-orbit coupling must be included in a quantitative theory.Comment: 5 pages, 4 figure

High contrast Mach-Zehnder lithium atom interferometer in the Bragg regime

We have constructed an atom interferometer of the Mach-Zehnder type, operating with a supersonic beam of lithium. Atom diffraction uses Bragg diffraction on laser standing waves. With first order diffraction, our apparatus has given a large signal and a very good fringe contrast (74%), which we believe to be the highest ever observed with atom interferometers. This apparatus will be applied to high sensitivity measurementsComment: 6 pages, 3 figures, accepted by Appl. Phys.

Poly[[tetra­kis­(μ2-pyrazine N,N′-dioxide-κ2 O:O′)holmium(III)] tris­(perchlorate)]

The title three-dimensional coordination network, {[Ho(C4H4N2O2)4](ClO4)3}n, is isostructural to that of other lanthanides. The Ho+3 cation lies on a fourfold roto-inversion axis. It is coordinated in a distorted square anti-prismatic fashion by eight O atoms from bridging pyrazine N,N′-dioxide ligands. There are two unique pyrazine N,N′-dioxide ligands. One ring is located around an inversion center, and there is a a twofold rotation axis at the center of the other ring. There are also two unique perchlorate anions. One is centered on a twofold rotation axis and the other on a fourfold roto-inversion axis. The perchlorate anions are located in channels that run perpendicular to (001) (110) and inter­act with the coordination network through C—H⋯O hydrogen bonds

X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue

AGN are known to have complex X-ray spectra that depend on both the properties of the accreting SMBH (e.g. mass, accretion rate) and the distribution of obscuring material in its vicinity ("torus"). Often however, simple and even unphysical models are adopted to represent the X-ray spectra of AGN. In the case of blank field surveys in particular, this should have an impact on e.g. the determination of the AGN luminosity function, the inferred accretion history of the Universe and also on our understanding of the relation between AGN and their host galaxies. We develop a Bayesian framework for model comparison and parameter estimation of X-ray spectra. We take into account uncertainties associated with X-ray data and photometric redshifts. We also demonstrate how Bayesian model comparison can be used to select among ten different physically motivated X-ray spectral models the one that provides a better representation of the observations. Despite the use of low-count spectra, our methodology is able to draw strong inferences on the geometry of the torus. For a sample of 350 AGN in the 4 Ms Chandra Deep Field South field, our analysis identifies four components needed to represent the diversity of the observed X-ray spectra: (abridged). Simpler models are ruled out with decisive evidence in favour of a geometrically extended structure with significant Compton scattering. Regarding the geometry of the obscurer, there is strong evidence against both a completely closed or entirely open toroidal geometry, in favour of an intermediate case. The additional Compton reflection required by data over that predicted by toroidal geometry models, may be a sign of a density gradient in the torus or reflection off the accretion disk. Finally, we release a catalogue with estimated parameters such as the accretion luminosity in the 2-10 keV band and the column density, $N_{H}$, of the obscurer.Comment: 28 pages, 18 figures, catalogue available from https://www.mpe.mpg.de/~jbuchner/agn_torus/analysis/cdfs4Ms_cat/, software available from https://github.com/JohannesBuchner/BX

Finding counterparts for All-sky X-ray surveys with Nway: a Bayesian algorithm for cross-matching multiple catalogues

We release the AllWISE counterparts and Gaia matches to 106,573 and 17,665 X-ray sources detected in the ROSAT 2RXS and XMMSL2 surveys with |b|>15. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding task with uncertain results. New all-sky multi-wavelength surveys of sufficient depth, like AllWISE and Gaia, and a new Bayesian statistics based algorithm, NWAY, allow us, for the first time, to provide reliable counterpart associations. NWAY extends previous distance and sky density based association methods and, using one or more priors (e.g., colors, magnitudes), weights the probability that sources from two or more catalogues are simultaneously associated on the basis of their observable characteristics. Here, counterparts have been determined using a WISE color-magnitude prior. A reference sample of 4524 XMM/Chandra and Swift X-ray sources demonstrates a reliability of ~ 94.7% (2RXS) and 97.4% (XMMSL2). Combining our results with Chandra-COSMOS data, we propose a new separation between stars and AGN in the X-ray/WISE flux-magnitude plane, valid over six orders of magnitude. We also release the NWAY code and its user manual. NWAY was extensively tested with XMM-COSMOS data. Using two different sets of priors, we find an agreement of 96% and 99% with published Likelihood Ratio methods. Our results were achieved faster and without any follow-up visual inspection. With the advent of deep and wide area surveys in X-rays (e.g. SRG/eROSITA, Athena/WFI) and radio (ASKAP/EMU, LOFAR, APERTIF, etc.) NWAY will provide a powerful and reliable counterpart identification tool.Comment: MNRAS, Paper accepted for publication. Updated catalogs are available at www.mpe.mpg.de/XraySurveys/2RXS_XMMSL2 . NWAY available at https://github.com/JohannesBuchner/nwa

Interaction of the ionic liquid [BMP][TFSA] with rutile TiO2(110) and coadsorbed lithium

Aiming at a fundamental understanding of the processes at the electrode|ionic liquid interface in Li ion batteries, we investigated the interaction of the ionic liquid n-butyl-n-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide [BMP][TFSA] and of Li with a reduced rutile TiO2(110) (1 × 1) surface as well as the interaction between [BMP][TFSA] and Li on the TiO2(110) surface under ultrahigh vacuum (UHV) conditions by X-ray photoelectron spectroscopy and scanning tunnelling microscopy. Between 80 K and 340 K [BMP][TFSA] adsorbs molecularly on the surface and at higher temperatures decomposition is observed, resulting in products such as Sad, Fad and TiNx. The decomposition pattern is compared to proposals based on theory. Small amounts of Li intercalate even at 80 K into TiO2(110), forming Li+ and Ti3+ species. The stoichiometry in the near surface region corresponds to Li7Ti5O12. For higher coverages in the range of several monolayers part of the Li remains on the surface, forming a Li2O cover layer. At 300 K, Ti3+ species become sufficiently mobile to diffuse into the bulk. Li post-deposition on a [BMP][TFSA] covered TiO2(110) surface at 80 K results in two competing reactions, Li intercalation and reaction with the IL, resulting in the decomposition of the IL. Upon warming up, the Ti3+ formed at low T is consumed by reaction with the IL adlayer and intermediate decomposition products. Post-deposition of [BMP][TFSA] (300 K) on a surface pre-covered with a Li2O/Li7Ti5O12 layer results in the partial reaction of [BMP][TFSA] with the Li+ and Ti3+ species, which gets completed at higher temperatures

New Approaches to Data-Driven Civilian Oversight of Law Enforcement: An Introduction to the Second NACOLE/CJPR Special Issue

In April of 2016, National Association for Civilian Oversight of Law Enforcement (NACOLE) and John Jay College partnered to sponsor the Academic Symposium “Building Public Trust: Generating Evidence to Enhance Police Accountability and Legitimacy.” This essay introduces the Criminal Justice Policy Review Special Issue featuring peer-reviewed, empirical research papers first presented at the Symposium. We provide context for the Symposium in relation to contemporary national discourse on police accountability and legitimacy. In addition, we review each of the papers presented at the Symposium, and provide in-depth reviews of each of the manuscripts included in the Special Issue

Psychostimulant Drug Abuse and Personality Factors in Medical Students

Purpose: This study was designed to examine the prevalence of psychostimulant drug abuse among medical students and to test the hypothesis that medical students who use psychostimulant drugs for non-medical reasons are characterized by a sensation seeking and aggressive-hostility personality and exhibit lower empathy