The guide star catalog

Part 1 of the catalog presents an astronomical overview of the Guide Star Catalog, together with its history, the properties of its current implementation, and the prospects for enhancement. Part 2 presents the algorithms used in photometric and astrometric calibration of the catalog, as well as the analyses of the related errors. Part 3 presents the current structure and content, as well as future enhancements in this area. An overview of the forthcoming publications is given, both with regard to scientific papers and electronic media

Kids these days

" Kids these days presents video, photography, and graphic works that draw from the fields of anthropology, psychology and sociology, to examine youth and youth cultures in the Canadian context. The artists document young people—their bodies, expressions, and movements—while investigating their tastes, thoughts, clothing styles, methods of communication, and leisure activities. The resulting artworks suggest an underlying desire on the part of the artists to capture the “essence” of youth or at least to affiliate themselves with the coveted values typically associated with this group: freedom, escape, authenticity, expressivity, creativity, and idealism. " -- Publisher's website

Catalog Matching with Astrometric Correction and its Application to the Hubble Legacy Archive

Object cross-identification in multiple observations is often complicated by the uncertainties in their astrometric calibration. Due to the lack of standard reference objects, an image with a small field of view can have significantly larger errors in its absolute positioning than the relative precision of the detected sources within. We present a new general solution for the relative astrometry that quickly refines the World Coordinate System of overlapping fields. The efficiency is obtained through the use of infinitesimal 3-D rotations on the celestial sphere, which do not involve trigonometric functions. They also enable an analytic solution to an important step in making the astrometric corrections. In cases with many overlapping images, the correct identification of detections that match together across different images is difficult to determine. We describe a new greedy Bayesian approach for selecting the best object matches across a large number of overlapping images. The methods are developed and demonstrated on the Hubble Legacy Archive, one of the most challenging data sets today. We describe a novel catalog compiled from many Hubble Space Telescope observations, where the detections are combined into a searchable collection of matches that link the individual detections. The matches provide descriptions of astronomical objects involving multiple wavelengths and epochs. High relative positional accuracy of objects is achieved across the Hubble images, often sub-pixel precision in the order of just a few milli-arcseconds. The result is a reliable set of high-quality associations that are publicly available online.Comment: 9 pages, 9 figures, accepted for publication in the Astrophysical Journa

Pictor A (PKS 0518-45) - From Nucleus to Lobes

We present radio and optical imaging and kinematic data for the radio galaxy Pictor A, including HST continuum and [OIII], emission-line images (at a resolution of 25 - 100 mas) and ground-based imaging and spectroscopy (at a resolution of ~ 1.5". The radio data include 3 cm Australia Telescope images of the core, at a resolution comparable to that of the optical, ground-based images, and a VLBI image of a jet in the compact core (at a resolution of 2 - 25 mas), which seems to align with a continuum ``jet'' found in the HST images. The core radio jet, the HST optical continuum ``jet'', and the NW H-alpha filaments all appear to point toward the optical-synchrotron hot-spot in the NW lobe of this object and are associated with a disrupted velocity field in the extended ionized gas. The ground-based spectra which cover this trajectory also yield line ratios for the ionized gas which have anomalously low [NII] (6564), suggesting either a complex, clumpy structure in the gas with a higher cloud-covering factor at larger radii and with denser clouds than is found in the nuclear regions of most NLRG and Seyfert 2 galaxies, or some other, unmodeled, mechanism for the emergent spectrum from this region. The H-alpha emission-line filaments to the N appear to be associated with a 3 cm radio continuum knot which lies in a gap in the filaments ~ 4" from the nucleus. Altogether, the data in this paper provide good circumstantial evidence for non-disruptive redirection of a radio jet by interstellar gas clouds in the host galaxy.Comment: 19 pages, 6 ps.gz fig pages, to appear in the Ap.J. Supp

ESCAlate – Adaptive treatment approach for adolescents and adults with ADHD: study protocol for a randomized controlled trial

Background: Over the last decade, a wide range of attention-deficit/hyperactivity disorder (ADHD) treatment approaches for adults, including both pharmacological interventions and psychosocial treatments, have been proposed and observed to be efficient. In practice, individual treatment concepts are based on results of clinical studies as well as international guidelines (NICE Guidelines) that recommend a step-by-step treatment approach. Since the evidence supporting this approach is limited, the aim of the present study is to determine an optimal intervention regarding severity levels of ADHD symptomatology conducting a randomized controlled trial. Method: We aim to include 279 ADHD subjects aged between 16 and 45 years. First, participants are randomized to either a face-to-face psychoeducation, telephone assisted self-help (TASH), or a waiting control group (Step 1). All participants assigned to the control group are treated using TASH after a 3-month waiting period. Participants are then allocated to one of three groups, based on their remaining severity level of ADHD symptoms, as (1) full responder, (2) partial responder, or (3) non-responder (Step 2). Full responders receive counseling, partial responders receive either counseling only or counseling and neurofeedback (NF), and non-responders receive either pharmacological treatment only or pharmacological treatment and NF, followed by a 3 month period without intervention. Discussion: The naturalistic sample is one of the study’s advantages, avoiding highly selective inclusion or exclusion criteria. The efficacy of an evidence-based stepped care intervention is explored by primary (reduction of severity of ADHD symptoms) and secondary outcomes (functional outcomes, e.g., quality of life, anger management, enhancement of psychosocial well-being). Predictors of therapeutic response and non-response are being investigated at each step of intervention. Further, sex differences are also being explored. Trial registration: This study is registered by the German Trial Register (reference number: DRKS00008975 ), 23 October 2015

Enhancing Dental Pulp Stem Cell Viability for Treatment of Spinal Cord Injury via Immune Cell Preconditioning

This item is only available electronically.Thesis (BHlthMSc(Hons)) -- University of Adelaide, Adelaide Medical School, YEA

Extracellular electrical signals in a neuron-surface junction: model of heterogeneous membrane conductivity

Signals recorded from neurons with extracellular planar sensors have a wide range of waveforms and amplitudes. This variety is a result of different physical conditions affecting the ion currents through a cellular membrane. The transmembrane currents are often considered by macroscopic membrane models as essentially a homogeneous process. However, this assumption is doubtful, since ions move through ion channels, which are scattered within the membrane. Accounting for this fact, the present work proposes a theoretical model of heterogeneous membrane conductivity. The model is based on the hypothesis that both potential and charge are distributed inhomogeneously on the membrane surface, concentrated near channel pores, as the direct consequence of the inhomogeneous transmembrane current. A system of continuity equations having non-stationary and quasi-stationary forms expresses this fact mathematically. The present work performs mathematical analysis of the proposed equations, following by the synthesis of the equivalent electric element of a heterogeneous membrane current. This element is further used to construct a model of the cell-surface electric junction in a form of the equivalent electrical circuit. After that a study of how the heterogeneous membrane conductivity affects parameters of the extracellular electrical signal is performed. As the result it was found that variation of the passive characteristics of the cell-surface junction, conductivity of the cleft and the cleft height, could lead to different shapes of the extracellular signals

Abundance analysis of prime B-type targets for asteroseismology II. B6--B9.5 stars in the field of view of the CoRoT

The CoRoT satellite is collecting precise time-resolved photometry for tens of asteroseismology targets. To ensure a correct interpretation of the CoRoT data, the atmospheric parameters, chemical compositions, and rotational velocities of the stars must be determined. The main goal of the ground-based seismology support program for the CoRoT mission was to obtain photometric and spectroscopic data for stars in the fields monitored by the satellite. These ground-based observations were collected in the GAUDI archive. High-resolution spectra of more than 200 B-type stars are available in this database, and about 45% of them is analysed here. To derive the effective temperature of the stars, we used photometric indices. Surface gravities were obtained by comparing observed and theoretical Balmer line profiles. To determine the chemical abundances and rotational velocities, we used a spectrum synthesis method, which consisted of comparing the observed spectrum with theoretical ones based on the assumption of LTE. Atmospheric parameters, chemical abundances, and rotational velocities were determined for 89 late-B stars. The dominant species in their spectra are iron-peak elements. The average Fe abundance is 7.24+/-0.45 dex. The average rotational velocity is 126 km/sec, but there are 13 and 20 stars with low and moderate Vsin i values, respectively. The analysis of this sample of 89 late B-type stars reveals many chemically peculiar (CP) stars. Some of them were previously known, but at least 9 new CP candidates, among which at least two HgMn stars, are identified in our study. These CP stars as a group exhibit Vsin i values lower than the stars with normal surface chemical composition.Comment: 21 pages, 13 figures, accepted to Astronomy and Astrophysic

Galactic structure studies with BATC star counts

We report the first results of star counts carried out with the National Astronomical Observatories (NAOC) 60/90 cm Schmidt Telescope in 15 intermediate-band filters from 3000 to 10000 {\AA} in the BATC survey. We analyze a sample of over 1400 main sequence stars ($14\le$V$\le21$), which lie in the field with central coordinates R.A.=$09^h53^m13^s.30$ and DEC=47$^\circ49^{\prime}00^{\prime\prime}.0$ (J2000). The field of view is 0.95 deg$^{2}$, and the spatial scale was 1\arcsec.67. In our model, the distribution of stars perpendicular to the plane of the Galaxy is given by two exponential disks (thin disk plus thick disk) and a de Vaucouleurs halo. Based on star counts, we derive the scale heights of the thin disk to be $320^{+14}_{-15}$ pc and of the thick disk to be $640^{+30}_{-32}$ pc, respectively, with a local density of $7.0\pm1$ of the thin disk. We find that the observed counts support an axial ratio of $c/a\le0.6$ for a de Vaucouleurs $r^{1/4}$ law, implying a more flattened halo. We also derive the stellar luminosity function (SLF) for the thin disk, and it partly agrees with the Hipparcos luminosity function.Comment: 17pages,9 figure