bluuebunny/crossref_metadata_2025 huggingface dataset:
GRAVITY: microarcsecond astrometry and deep interferometric imaging with the VLTI
Authors: Eisenhauer F. , Perrin G. , Straubmeier C. , Brandner W. , Boehm A. , Cassaing F. , Clenet Y. , Dodds-Eden K. , Eckart A. , Fedou P. , Gendron E. , Genzel R. , Gillessen S. , Graeter A. , Gueriau C. , Hamaus N. , Haubois X. , Haug M. , Henning T. , Hippler S. , Hofmann R. , Hormuth F. , Houairi K. , Kellner S. , Kervella P. , Klein R. , Kolmeder J. , Laun W. , Lena P. , Lenzen R. , Marteaud M. , Meschke D. , Naranjo V. , Neumann U. , Paumard T. , Perger M. , Perret D. , Rabien S. , Ramos J. R. , Reess J. M. , Rohloff R. R. , Rouan D. , Rousset G. , Ruyet B. , Schropp M. , Talureau B. , Thiel M. , Ziegleder J. , Ziegler D.
Published: July 2008

We present the adaptive optics assisted, near-infrared VLTI instrument GRAVITY for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. With its two fibers per telescope beam, its internal wavefront sensors and fringe tracker, and a novel metrology concept, GRAVITY will not only push the sensitivity far beyond what is offered today, but will also advance the astrometric accuracy for UTs to 10 μas. GRAVITY is designed to work with four telescopes, thus providing phase referenced imaging and astrometry for 6 baselines simultaneously. Its unique capabilities and sensitivity will open a new window for the observation of a wide range of objects, and — amongst others — will allow the study of motion within a few times the event horizon size of the Galactic Center black hole.
Occultation by (22) Kalliope and its satellite Linus
Authors: Sôma M. , Hayamizu T. , Miyashita K. , Setoguchi T. , Hirose T.
Published: July 2008

The occultation of a 9.1 magnitude star by asteroid (22) Kalliope and its satellite Linus was successfully observed in Japan in 2006 November 7.826 UT. This was the first definite observation of an occultation of a satellite of an asteroid that was discovered previously by other means. As a result the position of the satellite relative to Kalliope was obtained to be d = 0.246 ± 0.011 (arcsec), and P = 313.8 ± 2.7 (deg), where d is the angular distance and P is the position angle. The derived size for Kalliope is (209 ± 40)km × (136 ± 26)km (with the major axis in position angle of (8 ± 17) deg), and that for Linus is (33 ± 3) km. From the observations, the occulted star is also found to be a close double star whose separation is about 0.7 mas in position angle of about 300 deg, and the magnitudes of the components are found to be almost the same (~9.9 mag).
Astrometric observations of neutron stars
Authors: Chatterjee S.
Published: July 2008

Precision astrometry can yield model-independent distances and velocities for neutron stars. Such measurements can be exploited, for example, to locate neutron star birth sites, establish reference frame ties, model the Galactic electron density distribution, and constrain the astrophysics of supernova explosions. As a case study, I discuss recent some parallax and proper motion measurements, and their scientific implications for supernova core collapse and the velocities of ordinary pulsars versus magnetars. I also outline the calibration techniques that are enabling sub-milliarcsecond astrometry of neutron stars with VLBI. In the short term, systematic surveys and high sensitivity on very long baselines will produce ongoing science dividends from precision astrometry at radio wavelengths. In the longer term, new technology such as focal plane arrays, new telescopes such as the Square Kilometre Array, and synergy with new instruments such as Gaia, LSST, and GLAST, all hold great promise in an upcoming era of microarcsecond astrometry.
VLBA determinations of the distances to nearby star-forming regions
Authors: Loinard L. , Torres R. M. , Mioduszewski A. J. , Rodríguez L. F.
Published: July 2008

Using phase-referenced multi-epoch Very Long Baseline Array observations, we have measured the trigonometric parallax of several young stars in the Taurus and Ophiuchus star-forming regions with unprecedented accuracy. The mean distance to the Taurus complex was found to be about 140 pc, and its depth around 20 pc, comparable to the linear extent of Taurus on the sky. In Ophiuchus, 4 sources have been observed so far. Two of them were found to be at about 160 pc (the distance traditionally attributed to Ophiuchus), while the other 2 are at about 120 pc. Since the entire Ophiuchus complex is only a few parsecs across, this difference is unlikely to reflect the depth of the region. Instead, we argue that two physically unrelated sites of star-formation are located along the line of sight toward Ophiuchus.
VERA observation of the massive star forming region G34.4+0.23
Authors: Kurayama T.
Published: July 2008

We observed with VERA the massive star forming region G34.4+0.23, to obtain parallaxes and proper motions. Four infrared dark clouds were observed and water maser were found in two dark clouds, MM1 and MM4. In MM1, the distribution of maser spots shows a “V-shaped” structure and most features co-moving with this structure. Phase-referenced images have peaks and their motion is much larger than the expected parallax. Further analysis is needed to correctly interpret our measurement of parallax.
Milli-arcsecond binaries
Authors: Torres R. M. , Loinard L. , Mioduszewski A. J. , Rodríguez L. F.
Published: July 2008

As part of an astrometric program (see Loinard et al. in this volume), we have obtained an unprecedented sample of high-resolution (~ 1 mas) VLBA images of several nearby young stellar systems. As was to be expected, these images revealed interesting new characteristics of these objects. Perhaps the most interesting of these characteristics is the detection of a high rate of very tight binary stars (separations of a few mas) in our sample: of the 9 objects observed to date, 5 are binaries of this type.
The Gaia mission: science, organization and present status
Authors: Lindegren L. , Babusiaux C. , Bailer-Jones C. , Bastian U. , Brown A. G. A. , Cropper M. , Høg E. , Jordi C. , Katz D. , van Leeuwen F. , Luri X. , Mignard F. , de Bruijne J. H. J. , Prusti T.
Published: July 2008

The ESA space astrometry mission Gaia will measure the positions, parallaxes and proper motions of the 1 billion brightest stars on the sky. Expected accuracies are in the 7–25 μas range down to 15 mag and sub-mas accuracies at the faint limit (20 mag). The astrometric data are complemented by low-resolution spectrophotometric data in the 330–1000 nm wavelength range and, for the brighter stars, radial velocity measurements. The scientific case covers an extremely wide range of topics in galactic and stellar astrophysics, solar system and exoplanet science, as well as the establishment of a very accurate, dense and faint optical reference frame. With a planned launch around 2012 and an (extended) operational lifetime of 6 years, final results are expected around 2021. We give a brief overview of the science goals of Gaia, the overall project organisation, expected performance, and some key technical features and challenges.
Testing planet formation models with Gaia μas astrometry
Authors: Sozzetti A. , Casertano S. , Lattanzi M. G. , Spagna A. , Morbidelli R. , Pannunzio R. , Pourbaix D. , Queloz D.
Published: July 2008

In this paper, we first summarize the results of a large-scale double-blind tests campaign carried out for the realistic estimation of the Gaia potential in detecting and measuring planetary systems. Then, we put the identified capabilities in context by highlighting the unique contribution that the Gaia exoplanet discoveries will be able to bring to the science of extrasolar planets during the next decade.
Gaia: how to map a billion stars with a billion pixels
Authors: de Bruijne J. H. J.
Published: July 2008

Gaia, ESA's ambitious star-mapper mission due for launch late-2011, will provide multi-epoch micro-arcsecond astrometric and milli-magnitude photometric data for the brightest one billion objects in the sky, down to at least magnitude 20. Spectroscopic data will simultaneously be collected for the subset of the brightest 100 million stars, down to about magnitude 17. This massive data volume will allow astronomers to reconstruct the structure, evolution and formation history of the Milky Way. It will also revolutionize studies of the solar system and stellar physics and will contribute to diverse research areas, ranging from extra-solar planets to general relativity.

Underlying Gaia's scientific harvest will lie in a Catalogue, built on the fundamental space-based measurements. During the 5-year nominal operational lifetime, Gaia's payload, with its CCD mosaic containing 1 billion pixels, will autonomously detect all objects of interest and observe them throughout their passage of the focal plane. This paper discusses the workings of the Gaia instrument, details its payload, and discusses in depth how the scientific measurements will be collected. It addresses issues like maintenance of the scanning law, on-board data processing, the detection and confirmation of objects (single and multiple stars), the detection and rejection of cosmic rays and solar protons, the fundamental science measurements themselves composed of windows of CCD samples (pixels), and special strategies employed to maximize the science return for moving (i.e., solar-system) objects. The paper also explains how an on-board priority scheme will ensure catalogue completeness down to the faintest magnitudes possible, despite the limited ground-station availability and the enormous data volume that will be sent to the ground.
Gaia and the Astrometric Global Iterative Solution
Authors: Hobbs D. , Lindegren L. , Holl B. , Lammers U. , O'Mullane W.
Published: July 2008

Gaia is an ESA space astrometry mission due for launch in 2011–12. We describe part of the work carried out in the Gaia Data Processing and Analysis Consortium, namely the Astrometric Global Iterative Solution (AGIS) currently being implemented at the European Space Astronomy Center (ESAC) in Spain and largely based on algorithms developed at Lund Observatory. Some provisional results based on simulated observations of one million stars are presented, demonstrating convergence at microarcsec level independent of initial conditions.
Design of a compact astrometric instrument for the GAME mission
Authors: Loreggia D. , Gai M. , Vecchiato A. , Gardiol D. , Ligori S. , Lattanzi M. G.
Published: July 2008

We present the design of a Fizeau interferometer to be implemented for the GAME mission. The aim is to measure the PPN γ parameter with the same technique used for the first time by Dyson, Eddington et al., but at a 10−6 accuracy level. GAME will observe about 106 sufficiently bright stars at about 2° from the Sun. A dedicated space mission has the advantage of observing the light bending without waiting for an eclipse.
Astrometry by small ground-based telescopes
Authors: Thuillot W. , Stavinschi M. , Assafin M. ,   the IAU Working Group ASGBT
Published: July 2008

Many small ground-based telescopes (with diameter less than 2m) allow us to perform programs of observations well adapted to astrometric measurements. The improvement of limiting magnitudes thanks to the use of CCD detector and their availability make them very useful for follow-up programs or observations on alert. This communication gives several examples of research carried out by members of the IAU working group “Astrometry by small ground-based telescopes”. We also propose setting up of a network of observers for the Gaia follow-up observations.
Quasar astrophysics with the Space Interferometry Mission
Authors: Unwin S. C. , Wehrle A. E. , Meier D. L. , Jones D. L. , Piner B. G.
Published: July 2008

Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V=19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.
Gamma Astrometric Measurement Experiment: testing General Relativity with a small mission
Authors: Vecchiato A. , Lattanzi M. G. , Gai M. , Morbidelli R.
Published: July 2008

GAME (Gamma Astrometric Measurement Experiment) is a concept for an experiment whose goal is to measure from space the γ parameter of the Parameterized Post-Newtonian formalism, by means of a satellite orbiting at 1 AU from the Sun and looking as close as possible to its limb. This technique resembles the one used during the solar eclipse of 1919, when Dyson, Eddington and collaborators measured for the first time the gravitational bending of light. Simple estimations suggest that, possibly within the budget of a small mission, one could reach the 10−6level of accuracy with ~106observations of relatively bright stars at about 2° apart from the Sun. Further simulations show that this result could be reached with only 20 days of measurements on stars ofV≤ 17 uniformly distributed. A quick look at real star densities suggests that this result could be greatly improved by observing particularly crowded regions near the galactic center.
Dense optical reference frames: UCAC and URAT
Authors: Zacharias N.
Published: July 2008

A series of ground-based, dedicated astrometric, observational programs have been performed or are in preparation which provide a dense and accurate optical reference frame. Integral to all these programs are new observations to link the Hipparcos Celestial Reference Frame (HCRF) to the International Celestial Reference Frame (ICRF), based on compact, extragalactic radio sources.

The U.S. Naval Observatory CCD Astrograph Catalog (UCAC) 3rd release is in preparation. A pixel re-reduction is in progress to improve astrometric and photometric accuracy as well as completeness of this all-sky reference catalog to 16th magnitude. Optical counterparts of ICRF radio sources have been observed with 0.9-meter telescopes contemporaneously. Scanning of over 5000 early-epoch astrograph plates on StarScan has been completed. These data will improve the proper motions of stars in the 10 to 14 mag range for the UCAC3 release.

A 111 million-pixel CCD was successfully fabricated in 2006 and test observations at the USNO astrograph are underway. Four of such detectors will be used for the USNO Robotic Astrometric Telescope (URAT) focal plane assembly. Phase I of URAT will use the astrograph to reach 18th magnitude, while the new 0.85-meter telescope with a 4.5 deg diameter field of view will reach 21st magnitude. The URAT primary mirror has been fabricated.
Deep Astrometric Standards
Authors: Platais I. , Fey A. L. , Frey S. , Djorgovski S. G. , Ducourant C. , Ivezić Ž. , Rest A. , Veillet C. , Wyse R. F. G. , Zacharias N.
Published: July 2008

The advent of next-generation telescopes with very wide fields-of-view creates a need for deep and precise reference frames for astrometric calibrations. The Deep Astrometric Standards (DAS) program is designed to establish such a frame, by providing absolute astrometry at the 5–10 mas level in four 10 deg2 Galactic fields, to a depth of V=25. The source of our basic reference frame is the UCAC2 catalog, significantly improved by additional observations, and new VLBI positions of radio-loud and optically visible QSOs. We describe all the major steps in the construction of the DAS fields and provide the current status of this project.
VLBI observations of weak extragalactic radio sources for the alignment of the future Gaia frame with the ICRF
Authors: Bourda G. , Charlot P. , Porcas R. , Garrington S.
Published: July 2008

The space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between the optical and radio positions, it will be important to align the Gaia frame and the International Celestial Reference Frame (ICRF) with the highest accuracy. Currently, it is found that only 10% of the ICRF sources are suitable to establish this link, either because they are not bright enough at optical wavelengths or because they have significant extended radio emission which precludes reaching the highest astrometric accuracy. In order to improve the situation, we have initiated a VLBI survey dedicated to finding additional high-quality radio sources for aligning the two frames. The sample consists of about 450 sources, typically 20 times weaker than the current ICRF sources, which have been selected by cross-correlating optical and radio catalogues. This paper presents the observing strategy and includes preliminary results of observation of 224 of these sources with the European VLBI Network in June 2007.
Selection of stable sources from VLBI observations from 1984 to 2006
Authors: Qiao S. B. , Li J. L. , Zhang B. , Tian F.
Published: July 2008

Based on the Calc/Solve system and aiming at the selection of stable sources, we have obtained a series of global solutions to astrometric/geodetic VLBI observations from 1984 to 2006 by changing the settings of the control parameters. After comparing the solutions and performing statistical analysis we proposed a list of 173 candidate stable sources. We also compared the list with those recommended by others authors.
Re-calibration of GSC2.3 with UCAC2
Authors: Tang Z. H. , Qi Z. X. , Yu Y. , Smart R. L. , Bucciarelli B. , Lattanzi M. G. , Spagna A.
Published: July 2008

To make GSC-II more accurate and useful, it is necessary to re-calibrate GSC-II when a better reference catalogue (UCAC2) is available. With UCAC2 as the reference, preliminary re-calibration of some sample plates from GSC2.3 were carried out with different methods, such as Global, Mask and Filter. The results indicate that a 7th-order polynomial is sufficient to account for the influence of Schmidt plate deformation on the measured coordinates of stars. The magnitude equation can be eliminated after correcting for a common magnitude equation. The RMS of the re-calibrated data is around ±0.2~0.3 arcsec.
The second realization of the ICRF with VLBI
Authors: Ma C.
Published: July 2008

The ICRF derived from VLBI observations of extragalactic radio sources up to 1995.6 and effective since 1998.0 was a radical change from the FK5 stellar/equinox celestial system. Since then the number of geodetic/astrometric VLBI observations has tripled and the number of radio sources with astrometrically useful data has quadrupled. These data along with advances in modeling and estimation will be used to generate the next ICRF realization in the microwave band. Analysis of source position time series and source structure evolution will be used to select better “defining” sources. Working groups have been established by the IAU, IERS and IVS with the goal of presenting the second realization of the ICRF at the IAU General Assembly in 2009.
Opacity in compact extragalactic radio sources and its effect on radio-optical reference frame alignment
Authors: Kovalev Y. Y. , Lobanov A. P. , Pushkarev A. B. , Zensus J. A.
Published: July 2008

Accurate alignment of the radio and optical celestial reference frames requires detailed understanding of physical factors that may cause offsets between the positions of the same object measured in different spectral bands. Opacity in compact extragalactic jets (due to synchrotron self-absorption and external free-free absorption) is one of the key physical phenomena producing such an offset, and this effect is well-known in radio astronomy (“core shift”). We have measured the core shifts in a sample of 29 bright compact extragalactic radio sources observed by Very Long Baseline Interferometry (VLBI) at 2.3 and 8.6 GHz. We report the results of these measurements and estimate that the average shift between radio and optical positions of distant quasars could be of the order of 0.1--0.2 mas. This shift exceeds the expected positional accuracy of Gaia and SIM. We suggest two possible approaches to carefully investigate and correct for this effect in order to align accurately the radio and optical positions. Both approaches involve determining a Primary Reference Sample of objects to be used for tying the radio and optical reference frames together.
Asteroid mass determination with the Gaia mission
Authors: Mouret S. , Hestroffer D. , Mignard F.
Published: July 2008

The ESA astrometric mission Gaia, due for launch in late 2011, will observe a very large number of asteroids (~ 350,000 down to the magnitude 20), most from the main belt, with an unprecedented positional precision (at the sub-milliarcsecond level). Such high-precision astrometry will enable to considerably improve the orbits of a large number of objects, and also to determine the masses of the largest asteroids by analyzing their gravitational pull during close encounters with smaller ones. A global solution involving simultaneously all the perturbers and the smaller targets should yield about hundred masses with a precision better than 30 percent. The knowledge of these masses will be a rich source of information on the physics of main-belt asteroids and will increase the accuracy of modern solar system ephemerides. We outline the principle of the mathematical method based on variational equations developed to solve for the orbital parameters and the masses of the largest bodies. Calculations have been performed by taking into account realistic simulation of the Gaia observations such as geometry, time sequence, magnitude and by considering possible close approaches among 350,000 asteroids. We give a list of asteroids whose mass can be estimated along with its formal precision.
The RAMOD astrometric observable and the relativistic astrometric catalogs
Authors: Crosta M. T. , Bucciarelli B. , de Felice F. , Lattanzi M. G. , Vecchiato A.
Published: July 2008

We describe a way to compare current relativistic astrometric models accurate to the micro-arcsecond level. The observed stellar direction can be written as a function of several parts, linking the astrometric observables to the relativistic effects associated to the stellar kinematical properties and distances as seen inside the gravitational field of our Solar System, i.e. the so called relativistic astrometric parameters, providing a tool for comparing the RAMOD framework to the pM/pN approaches.
Stars in the age of micro-arc-second astrometry
Authors: Lebreton Y.
Published: July 2008

The understanding and modelling of the structure and evolution of stars is based on statistical physics as well as on hydrodynamics. Today, a precise identification and proper description of the physical processes at work in stellar interiors are still lacking (one key point being that of transport processes) while comparison of real stars to model predictions, which implies conversions from the theoretical space to the observational one, suffers from uncertainties in model atmospheres. This results in uncertainties on the prediction of stellar properties needed for galactic studies or cosmology (as stellar ages and masses). In the next decade, progress is expected from the theoretical, experimental and observational sides. I illustrate some of the problems we are facing when modelling stars and possible ways toward their solutions. I discuss how future observational ground-based or spatial programs (in particular those dedicated to micro-arc-second astrometry, asteroseismology and interferometry) will provide precise determinations of the stellar parameters and contribute to a better knowledge of stellar interiors and atmospheres in a wide range of stellar masses, chemical composition and evolution stages.
The ESPRI project: narrow-angle astrometry with VLTI-PRIMA
Authors: Launhardt R. , Henning T. , Queloz D. , Quirrenbach A. , Delplancke F. , Elias N. M. , Pepe F. , Reffert S. , Ségransan D. , Setiawan J. , Tubbs R. ,   the ESPRI consortium
Published: July 2008

We describe the ongoing hardware and software developments that shall enable the ESO VLTI to perform narrow-angle differential delay astrometry in K-band with an accuracy of up to 10 μarcsec. The ultimate goal of these efforts is to perform an astrometric search for extrasolar planets around nearby stars.
Spying on your neighbors with ultra-high precision
Authors: Jao W. C. , Henry T. J. , Subasavage J. P. , Ianna P. A. , Costa E. , Méndez R. A. ,   the RECONS Team
Published: July 2008

We are entering the era of microarcsecond astrometric accuracy. Breaking the milliarcsecond barrier will lead to consequent leaps in astronomical understanding of diverse topics. Here we review some current ground-based trigonometric parallax efforts and their recent scientific results. We highlight the current status of nearby star research, including the RECONS census of stars within a 10 pc horizon, white dwarfs and cool subdwarfs, and the push to detect substellar objects via astrometry. We also provide details about recent improvements in the methodology that have permitted the determination of parallaxes with ~1 milliarcsecond accuracy, and what might be done to push routinely into the sub-millarcsecond regime.
L and T dwarfs in Gaia/SIM
Authors: Smart R. L. , Bucciarelli B. , Lattanzi M. G. , Jones H. R. A.
Published: July 2008

We discuss the role of distances for understanding brown dwarfs and estimate the contribution expected by Gaia. We show that Gaia will only observe 25% of L and T dwarfs within 50pc which, at a conservative estimate, amounts to less than 400 objects. We discuss how Gaia results will nevertheless aid the ground-based programs providing reliable, bias free constraints for the calculation of parallaxes in an absolute system. We list the current ground-based programs underway and the possibilities for future all sky survey programs.
Modelling the Galaxy from survey data
Authors: Robin A. C. , Reylé C. , Marshall D.
Published: July 2008

Recent optical and near-infrared surveys have considerably improved our knowledge of galactic structure and galactic evolution. Two ways can be used to infer this knowledge from datasets: either inversing the data to get parameters describing the Galaxy, or using a synthetic approaches to test scenarios of formation and theoretical models for star and galaxy formation and evolution, both approaches being complementary. Using the synthetic approach the Besancon Galaxy model allows to test scenarios for the structure and evolution of the Galaxy by comparing simulations with the survey data. Examples are given using the 2MASS survey. Future uses of astrometric survey data are shown to be able to efficiently constrain the kinematics and dynamics of the Galaxy.
Microarcsecond astrometry in the Local Group
Authors: Brunthaler A. , Reid M. J. , Falcke H. , Henkel C. , Menten K. M.
Published: July 2008

Measuring the proper motions and geometric distances of galaxies within the Local Group is very important for our understanding of its history, present state and future. Currently, proper motion measurements using optical methods are limited only to the closest companions of the Milky Way. However, given that VLBI provides the best angular resolution in astronomy and phase-referencing techniques yield astrometric accuracies of ≈ 10 micro-arcseconds, measurements of proper motions and angular rotation rates of galaxies out to a distance of ~ 1 Mpc are feasible. This paper presents results of VLBI observations in regions of H2O maser activity of the Local Group galaxies M33 and IC 10. Two masing regions in M33 are on opposite sides of the galaxy. This allows a comparison of the angular rotation rate (as measured by the VLBI observations) with the known inclination and rotation speed of the Hi gas disk leading to a determination of a geometric distance of 730 ± 100 ± 135 kpc. The first error indicates the statistical error of the proper-motion measurements, while the second error is the systematic error of the rotation model. Within the errors, this distance is consistent with the most recent Cepheid distance to M33. Since all position measurements were made relative to an extragalactic background source, the proper motion of M33 has also been measured. This provides a three dimensional velocity vector of M33, showing that this galaxy is moving with a velocity of 190 ± 59 km s−1 relative to the Milky Way. For IC 10, we obtain a motion of 215 ± 42 km s−1 relative to the Milky Way. These measurements promise a new handle on dynamical models for the Local Group and the mass and dark matter halo of Andromeda and the Milky Way.
Calibration of stellar parameters using high-precision parallaxes
Authors: Butkevich A. G. , Berdyugin A. V. , Teerikorpi P.
Published: July 2008

Utilization of sub-milliarcsecond trigonometric parallaxes shifts the classical problem of calibration of stellar parameters to a new level of complexity. Derivation of stellar luminosity from the parallaxes is not a straightforward task with a number of statistical effects, such as Malmquist bias, to be taken into account. Different methods are to be used in order to derive parameters of luminosity function depending on the nature of underlying stellar sample. It is emphasized that any combination of astrometric parameters (i.e. parallaxes) and astrophysical ones must be handled carefully to avoid or reduce statistical effects, which otherwise may seriously affect the astrophysical applications.
Simultaneous Bayesian estimation of distances and ages from isochrones: SDSS and solar neighborhood FGK stars
Authors: Franchini M. , Morossi C. , Di Marcantonio P. , Malagnini M. L.
Published: July 2008

By using a procedure based on the Bayesian probability theory we computed reliable and self–consistent estimates of absolute magnitude and age for about 2000 FKG spectral-type stars from SDSS–DR5, ELODIE, and INDO–US surveys, with effective temperature, surface gravity, and metallicity values homogeneously derived.
A spectroscopic survey of late-type giants in the Milky Way disk and local halo substructure
Authors: Sheffield A. A. , Majewski S. R. , Cheung A. M. , Hampton C. M. , Crane J. D. , Patterson R. J.
Published: July 2008

We report the results of a survey of late-type giants aimed at understanding the nature of the disk and nearby halo Galactic stellar populations. We have obtained medium resolution (2–4 Å) spectra for 749 late K and early M giants at mid-latitudes selected from the 2MASS catalog with the FOBOS system at Fan Mountain Observatory. These spectra provide radial velocities (RVs) at the 5 km s−1 level, spectroscopic [Fe/H] good to σ[Fe/H] = 0.25 dex, and information on the relative abundances of Mg/Fe and Na/Fe in these stars. Proper motions from UCAC2 are used to search for local substructures, in particular the leading arm of the Sagittarius tidal streamer passing through the solar neighborhood. The combined proper motions and RVs yield full 6D stellar space motions. We have, by way of kinematics, relatively cleanly isolated the thick disk from the typically high velocity substructures that compose the nearby halo.

We find evidence for substructure in the kinematics and metallicities of local halo stars.
Development of a near-infrared high-resolution spectrograph (WINERED) for a survey of bulge stars
Authors: Tsujimoto T. , Kobayashi N. , Yasui C. , Kondo S. , Minami A. , Motohara K. , Ikeda Y. , Gouda N.
Published: July 2008

We are developing a new near-infrared high-resolution (R[max] = 100,000) and high-sensitive spectrograph WINERED, which is specifically customized for short NIR bands at 0.9–1.35 μm. WINERED employs an innovative optical system; a portable design and a warm optics without any cold stops. The planned astrometric space mission JASMINE will provide precise positions, distances, and proper motions of the bulge stars. The missing components, the radial velocity and chemical composition will be measured by WINERED. These combined data brought by JASMINE and WINERED will certainly reveal the nature of the Galactic bulge. We plan to complete this instrument for observations of single objects by the end of 2008 and to attach it to various 4–10m telescopes as a PI-type instrument. We hope to upgrade WINERED with a multi-object feed in the future for efficient survey of the JASMINE bulge stars.
Astrometric education in Saint-Petersburg State University, Russia
Authors: Kumkova I. I. , Vityazev V. V.
Published: July 2008

The present system of astrometric education in the Saint-Petersburg State University is presented. The general courses, specific programs, seminars and observations that a student takes during a 5-year educational program are described.
Acoustic astrometry with a VLBI-like interferometer
Authors: Martí-Vidal I. , Marcaide J. M.
Published: July 2008

We show how loud-speakers, home digital recorders, and a common personal computer can be used to emulate VLBI observations on a small scale. These audio-VLBI observations allow for single-field astrometry (sources within the same interferometric field), differential group-delay astrometry, etc. These experiments can be set up very easily and in many possible configurations. Students may find these experiments very useful to learn about the innermost details of the interferometric technique.
Astronomical databases of Nikolaev Observatory
Authors: Protsyuk Y. , Mazhaev A.
Published: July 2008

Several astronomical databases were created at Nikolaev Observatory during the last years. The databases are built by using MySQL search engine and PHP scripts. They are available on NAO web-site http://www.mao.nikolaev.ua.
Validität und Reliabilität des FPI-R beim Einsatz im Strafvollzug
Authors: Hosser Daniela , Lauterbach Oliver , Camehn Kerstin
Published: July 2008

Zusammenfassung. Das Freiburger Persönlichkeitsinventar (FPI-R), ein häufig im Strafvollzug verwendeter Test, wird anhand einer Inhaftiertenstichprobe bezüglich seiner psychometrischen Eigenschaften (Validität und Reliabilität) untersucht. Grundlage sind die Testdaten von 775 männlichen deutschen Inhaftierten aus dem Jugendstrafvollzug, die den Test im Rahmen der vollzuglichen Eingangsdiagnostik bearbeiteten. Konfirmatorische Faktoranalysen zeigen, dass sich die Faktorenstruktur des FPI-R nur teilweise replizieren lässt. Die psychometrischen Kennwerte der FPI-R-Skalen fallen deutlich schlechter aus als in der Normstichprobe und sind insbesondere für die Skalen Lebenszufriedenheit und Leistungsorientierung nicht zufriedenstellend. Die Testwerte der Inhaftierten weichen bezüglich der Skalen Aggressivität, Gehemmtheit und Soziale Orientierung in erwartungswidriger Richtung von den altersspezifischen Normwerten ab. Die Befunde werden im Hinblick auf den Einsatz des FPI-R im Strafvollzug diskutiert.
Gegenseitige Wertschätzung
Authors: Becker-Glauch Wulf
Published: July 2008

Zusammenfassung. Für die Evaluation der Künste (auch der künstlerischen Therapien) gegenseitig gibt es große Beispiele. Hier geht es um ein Bild und ein Gedicht, denen die gegenseitige Wertschätzung der Personen und ihrer Kunst zu Grunde liegt: das Rilke-Porträt von Modersohn-Becker und das ,Selbstbildnis aus dem Jahre 1906’ von Rilke als Entgegnung. Die Künstlerin malte Rilke in Voraussicht seiner Entwicklung als Orpheus und sich selber bald darauf im gleichen mythologisch-archetypischen Bezug. In solchem Zusammenhang beschäftigt sich die essayistische Darstellung mit der Leben und Tod umschließenden Orphik (ca. 500 v.–500 n. Chr.) und ihrem Lied als Daseinsform, die noch Goethe in ,Urworte. Orphisch’ gestaltet und weitergegeben hat. In dieser Tradition steht auch das Lied in der Musik- und Tanztherapie von Karl Hörmann.
Suicide and Undetermined Deaths Among Youths and Young Adults in Latin America
Authors: Pritchard Colin , Hean Sarah
Published: July 2008

In Latin American (LA) and the major developed countries (MDC) suicide and undetermined deaths are analyzed as methods of suicide and the number of undetermined deaths are similar, possibly containing hidden suicides. The goal was to test the likelihood that LA cultural attitudes lead to higher undetermined rates and more hidden suicides. We used 3-year WHO average mortality data to compare LA and MDC mortality by age and gender, and χ² tests to examine any differences. In 13 LA countries younger-aged (15–34) men and womens suicides were higher than all-age rates, and undetermined deaths exceeded the suicide rates. Nine LA countries had significantly more undetermined younger-aged male deaths than females. Sixteen of 18 LA countries had significantly higher undetermined death rates than the MDC. LA younger-aged malefs24 146s differential suicide: Undetermined rates indicated they may contain substantial numbers of hidden suicides. Inadvertently, cultural attitudes to suicide may hinder prevention.
Pattern of Deliberate Self-Harm in Young People in Karachi, Pakistan
Authors: Syed Ehsan Ullah , Khan Murad M.
Published: July 2008

Globally, suicide remains one of the leading causes of death among individuals aged 10 to 64 years and it ranks between second and fourth among those age 10 to 45 years. Data on suicidal behavior from Pakistan is sparse, especially for children and adolescents. A retrospective descriptive case note study was carried out of all patients under the age of 18 years (n = 69) admitted with deliberate self-harm (DSH) to a university hospital in Karachi, Pakistan. Females (63.8%) outnumbered males by 1.7:1. The mean age of the group was 16 years (± 2.2). The most frequent method used was benzodiazepine overdose (30.4%). Family conflicts was the main stressor reported by 66.7%. The most frequent diagnosis made was major depressive disorder in 18%. Despite the fact that 98% of our sample was Muslims and suicide is strictly forbidden in Islam, 76.8% expressed their intent to die. Multivariate logistic regression found current stressor to be significantly associated with an intention to die. Patients with nonfatal suicidal behavior form a pool for future suicides. Preventive efforts should be directed at this group. School based programs would be an effective way of addressing this.
The Most Common Method of Suicide in Tehran 2000–2004
Authors: Razaeian Mohsen , Mohammadi Maryam , Akbari Malihe , Maleki Maryam
Published: July 2008

The likelihood of completing suicide depends to some extent on knowledge of effective means and also on the availability and/or acceptability of such methods. Since studying suicide methods may have an implication for prevention, the focus of this study was on the most favored method of suicide in Tehran, Iran. The study uses confirmed suicide data provided by the Beheshet Zahra Organization (BZO), which gathers all mortality data within Tehran and enters them into a computerized database, from which the relevant information for all the recorded suicide cases during the year 2000 to 2004 were obtained and analyzed. There were 703 cases of suicide (632 males and 71 females) in the BZO database, with a sex ratio of 8.9. The mean (standard deviation) of age at suicide for those who chose hanging and for those who have chosen other methods of suicide were 33.93 (14.2) and 34.60 (13.4) years, respectively. Hanging was the method favored by 572 (85.9%) of cases. Use of hanging was higher in females (61, 85.9%) than in males (511, 80.9%), and higher among the married (304, 53.6%) than among singles (268, 46.4%). The high proportion of persons using hanging as a method of suicide in Tehran may reflect the fact that this method is more acceptable and/or easily available and/or less likely to be misclassified as accidental or undetermined death. The prevention of such suicides is extremely difficult in the general population. Therefore, it is suggested that, to prevent suicide by hangings, the authorities should focus on the causal factors of suicide rather than on the acceptability and/or the availability of this method.
Phosphorylation of hepatitis B virus core C-terminally truncated protein (Cp149) by PKC increases capsid assembly and stability
Authors: Kang Hang , Yu Jaehoon , Jung Guhung
Published: July 2008

The HBV (hepatitis B virus) core is a phosphoprotein whose assembly, replication, encapsidation and localization are regulated by phosphorylation. It is known that PKC (protein kinase C) regulates pgRNA (pregenomic RNA) encapsidation by phosphorylation of the C-terminus of core, which is a component packaged into capsid. Neither the N-terminal residue phosphorylated by PKC nor the role of the C-terminal phosphorylation have been cleary defined. In the present study we found that HBV Cp149 (core protein C-terminally truncated at amino acid 149) expressed in Escherichia coli was phosphorylated by PKC at Ser106. PKC-mediated phosphorylation increased core affinity, as well as assembly and capsid stability. In vitro phosphorylation with core mutants (S26A, T70A, S106A and T114A) revealed that the Ser106 mutation inhibited phosphorylation of core by PKC. CD analysis also revealed that PKC-mediated phosphorylation stabilized the secondary structure of capsid. When either pCMV/FLAG-Cp149[WT (wild-type)] or pCMV/FLAG-S106A Cp149 was transfected into Huh7 human hepatoma cells, mutant capsid level was decreased by 2.06-fold with the S106A mutant when compared with WT, although the same level of total protein was expressed in both cases. In addition, when pUC1.2x and pUC1.2x/S106A were transfected, mutant virus titre was decreased 2.31-fold compared with WT virus titre. In conclusion, PKC-mediated phosphorylation increased capsid assembly, stability and structural stability.
Veterinary Generics: An Enigma among Niche Markets
Authors: Hoffman Jean , Perkins Christina
Published: July 2008

This paper examines the opportunities and challenges pharmaceutical companies encounter when considering entry into the niche US veterinary generics market. The key points compare the growth of the companion animal market as an attractive lure for potential entrants, to the regulatory hurdles of drug approval, drug distribution and veterinarian relationships and education that could dissuade companies from testing the waters of veterinary generics.
Liquid-crystal NMR structure of HIV TAR RNA bound to its SELEX RNA aptamer reveals the origins of the high stability of the complex
Authors: Van Melckebeke Hélène , Devany Matthew , Di Primo Carmelo , Beaurain François , Toulmé Jean-Jacques , Bryce David L. , Boisbouvier Jérôme
Published: July 2008

Transactivation-response element (TAR) is a stable stem–loop structure of HIV RNA, which plays a crucial role during the life cycle of the virus. The apical loop of TAR acts as a binding site for essential cellular cofactors required for the replication of HIV. High-affinity aptamers directed against the apical loop of TAR have been identified by the SELEX approach. The RNA aptamers with the highest affinity for TAR fold as hairpins and form kissing complexes with the targeted RNA through loop–loop interactions. The aptamers with the strongest binding properties all possess a GA base pair combination at the loop-closing position. Using liquid-crystal NMR methodology, we have obtained a structural model in solution of a TAR–aptamer kissing complex with an unprecedented accuracy. This high-resolution structure reveals that the GA base pair is unilaterally shifted toward the 5′ strand and is stabilized by a network of intersugar hydrogen bonds. This specific conformation of the GA base pair allows for the formation of two supplementary stable base-pair interactions. By systematic permutations of the loop-closing base pair, we establish that the identified atomic interactions, which form the basis for the high stability of the complex, are maintained in several other kissing complexes. This study rationalizes the stabilizing role of the loop-closing GA base pairs in kissing complexes and may help the development or improvement of drugs against RNA loops of viruses or pathogens as well as the conception of biochemical tools targeting RNA hairpins involved in important biological functions.
Crystal structure of the yeast eIF4A-eIF4G complex: An RNA-helicase controlled by protein–protein interactions
Authors: Schütz Patrick , Bumann Mario , Oberholzer Anselm Erich , Bieniossek Christoph , Trachsel Hans , Altmann Michael , Baumann Ulrich
Published: July 2008

Translation initiation factors eIF4A and eIF4G form, together with the cap-binding factor eIF4E, the eIF4F complex, which is crucial for recruiting the small ribosomal subunit to the mRNA 5′ end and for subsequent scanning and searching for the start codon. eIF4A is an ATP-dependent RNA helicase whose activity is stimulated by binding to eIF4G. We report here the structure of the complex formed by yeast eIF4G's middle domain and full-length eIF4A at 2.6-Å resolution. eIF4A shows an extended conformation where eIF4G holds its crucial DEAD-box sequence motifs in a productive conformation, thus explaining the stimulation of eIF4A's activity. A hitherto undescribed interaction involves the amino acid Trp-579 of eIF4G. Mutation to alanine results in decreased binding to eIF4A and a temperature-sensitive phenotype of yeast cells that carry a Trp579Ala mutation as its sole source for eIF4G. Conformational changes between eIF4A's closed and open state provide a model for its RNA-helicase activity.
Defining diversity, specialization, and gene specificity in transcriptomes through information theory
Authors: Martínez Octavio , Reyes-Valdés M. Humberto
Published: July 2008

The transcriptome is a set of genes transcribed in a given tissue under specific conditions and can be characterized by a list of genes with their corresponding frequencies of transcription. Transcriptome changes can be measured by counting gene tags from mRNA libraries or by measuring light signals in DNA microarrays. In any case, it is difficult to completely comprehend the global changes that occur in the transcriptome, given that thousands of gene expression measurements are involved. We propose an approach to define and estimate the diversity and specialization of transcriptomes and gene specificity. We define transcriptome diversity as the Shannon entropy of its frequency distribution. Gene specificity is defined as the mutual information between the tissues and the corresponding transcript, allowing detection of either housekeeping or highly specific genes and clarifying the meaning of these concepts in the literature. Tissue specialization is measured by average gene specificity. We introduce the formulae using a simple example and show their application in two datasets of gene expression in human tissues. Visualization of the positions of transcriptomes in a system of diversity and specialization coordinates makes it possible to understand at a glance their interrelations, summarizing in a powerful way which transcriptomes are richer in diversity of expressed genes, or which are relatively more specialized. The framework presented enlightens the relation among transcriptomes, allowing a better understanding of their changes through the development of the organism or in response to environmental stimuli.