556 research outputs found
Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18
Combining the precise parallaxes and optical photometry delivered by Gaia's
second data release (Gaia DR2) with the photometric catalogues of PanSTARRS-1,
2MASS, and AllWISE, we derive Bayesian stellar parameters, distances, and
extinctions for 265 million stars brighter than G=18. Because of the wide
wavelength range used, our results substantially improve the accuracy and
precision of previous extinction and effective temperature estimates. After
cleaning our results for both unreliable input and output data, we retain 137
million stars, for which we achieve a median precision of 5% in distance, 0.20
mag in V-band extinction, and 245 K in effective temperature for G<14,
degrading towards fainter magnitudes (12%, 0.20 mag, and 245 K at G=16; 16%,
0.23 mag, and 260 K at G=17, respectively). We find a very good agreement with
the asteroseismic surface gravities and distances of 7000 stars in the Kepler,
the K2-C3, and the K2-C6 fields, with stellar parameters from the APOGEE
survey, as well as with distances to star clusters. Our results are available
through the ADQL query interface of the Gaia mirror at the Leibniz-Institut
f\"{u}r Astrophysik Potsdam (gaia.aip.de) and as binary tables at data.aip.de.
As a first application, in this paper we provide distance- and
extinction-corrected colour-magnitude diagrams, extinction maps as a function
of distance, and extensive density maps, demonstrating the potential of our
value-added dataset for mapping the three-dimensional structure of our Galaxy.
In particular, we see a clear manifestation of the Galactic bar in the stellar
density distributions, an observation that can almost be considered a direct
imaging of the Galactic bar.Comment: 25 pages, 23 figures + appendix, accepted for publication in A&A.
Data (doi:10.17876/gaia/dr.2/51) are available through ADQL queries at
gaia.aip.d
Pathway to the Square Kilometre Array - The German White Paper -
The Square Kilometre Array (SKA) is the most ambitious radio telescope ever
planned. With a collecting area of about a square kilometre, the SKA will be
far superior in sensitivity and observing speed to all current radio
facilities. The scientific capability promised by the SKA and its technological
challenges provide an ideal base for interdisciplinary research, technology
transfer, and collaboration between universities, research centres and
industry. The SKA in the radio regime and the European Extreme Large Telescope
(E-ELT) in the optical band are on the roadmap of the European Strategy Forum
for Research Infrastructures (ESFRI) and have been recognised as the essential
facilities for European research in astronomy.
This "White Paper" outlines the German science and R&D interests in the SKA
project and will provide the basis for future funding applications to secure
German involvement in the Square Kilometre Array.Comment: Editors: H. R. Kl\"ockner, M. Kramer, H. Falcke, D.J. Schwarz, A.
Eckart, G. Kauffmann, A. Zensus; 150 pages (low resolution- and colour-scale
images), published in July 2012, language English (including a foreword and
an executive summary in German), the original file is available via the MPIfR
homepag
Neurotrophin gene augmentation by electrotransfer to improve cochlear implant hearing outcomes
This Review outlines the development of DNA-based therapeutics for treatment of hearing loss, and in particular, considers the potential to utilize the properties of recombinant neurotrophins to improve cochlear auditory (spiral ganglion) neuron survival and repair. This potential to reduce spiral ganglion neuron death and indeed re-grow the auditory nerve fibres has been the subject of considerable pre-clinical evaluation over decades with the view of improving the neural interface with cochlear implants. This provides the context for discussion about the development of a novel means of using cochlear implant electrode arrays for gene electrotransfer. Mesenchymal cells which line the cochlear perilymphatic compartment can be selectively transfected with (naked) plasmid DNA using array - based gene electrotransfer, termed âclose-field electroporationâ. This technology is able to drive expression of brain derived neurotrophic factor (BDNF) in the deafened guinea pig model, causing re-growth of the spiral ganglion peripheral neurites towards the mesenchymla cells, and hence into close proximity with cochlear implant electrodes within scala tympani. This was associated with functional enhancement of the cochlear implant neural interface (lower neural recruitment thresholds and expanded dynamic range, measured using electrically - evoked auditory brainstem responses). The basis for the efficiency of close-field electroporation arises from the compression of the electric field in proximity to the ganged cochlear implant electrodes. The regions close to the array with highest field strength corresponded closely to the distribution of bioreporter cells (adherent human embryonic kidney (HEK293)) expressing green fluorescent reporter protein (GFP) following gene electrotransfer. The optimization of the gene electrotransfer parameters using this cell-based model correlated closely with in vitro and in vivo cochlear gene delivery outcomes. The migration of the cochlear implant electrode array-based gene electrotransfer platform towards a clinical trial for neurotrophin-based enhancement of cochlear implants is supported by availability of a novel regulatory compliant mini-plasmid DNA backbone (pFAR4; plasmid Free of Antibiotic Resistance v.4) which could be used to package a âhumanizedâ neurotrophin expression cassette. A reporter cassette packaged into pFAR4 produced prominent GFP expression in the guinea pig basal turn perilymphatic scalae. More broadly, close-field gene electrotransfer may lend itself to a spectrum of potential DNA therapeutics applications benefitting from titratable, localised, delivery of naked DNA, for gene augmentation, targeted gene regulation, or gene substitution strategies
Spallation Neutron Production by 0.8, 1.2 and 1.6 GeV Protons on various Targets
Spallation neutron production in proton induced reactions on Al, Fe, Zr, W,
Pb and Th targets at 1.2 GeV and on Fe and Pb at 0.8, and 1.6 GeV measured at
the SATURNE accelerator in Saclay is reported. The experimental
double-differential cross-sections are compared with calculations performed
with different intra-nuclear cascade models implemented in high energy
transport codes. The broad angular coverage also allowed the determination of
average neutron multiplicities above 2 MeV. Deficiencies in some of the models
commonly used for applications are pointed out.Comment: 20 pages, 32 figures, revised version, accepted fpr publication in
Phys. Rev.
<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties
Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7.
Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release.
Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue.
Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues â a realisation of the Tycho-Gaia Astrometric Solution (TGAS) â and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of âŒ3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yrâ1 for the proper motions. A systematic component of âŒ0.3 mas should be added to the parallax uncertainties. For the subset of âŒ94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yrâ1. For the secondary astrometric data set, the typical uncertainty of the positions is âŒ10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to âŒ0.03 mag over the magnitude range 5 to 20.7.
Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data
Challenging cisgenderism through trans people's narratives of domestic violence and abuse
By drawing on empirical research that explored trans peopleâs experiences of domestic violence and abuse (DVA), this paper problematises the âgender asymmetry debate' in DVA discourse. It does so by highlighting cisgenderism and a heteronormative bias which have led to the invisibility of a trans perspective. Qualitative data was collected via narrative interviews and this was examined using a voice-centred relational technique. A total of twenty four interviews were undertaken with trans people (n = 15) and domestic abuse practitioners (n = 9). In relation to the presentation and impact of DVA, and in the context of trans and cisgender people's abuse experiences, the research findings report both similarities and differences. Four narratives are presented here to illuminate both. This paper adds new insight and challenges normative and dominant discourses by promoting the need for further theorising about the gendered nature of domestic violence and abuse
4MOST Scientific Operations
The 4MOST instrument is a multi-object spectrograph that will address
Galactic and extragalactic science cases simultaneously by observing targets
from a large number of different surveys within each science exposure. This
parallel mode of operation and the survey nature of 4MOST require some distinct
4MOST-specific operational features within the overall operations model of ESO.
The main feature is that the 4MOST Consortium will deliver, not only the
instrument, but also contractual services to the user community, which is why
4MOST is also described as a facility. This white paper concentrates on
information particularly useful to answering the forthcoming Call for Letters
of Intent.Comment: Part of the 4MOST issue of The Messenger, published in preparation of
4MOST Community Workshop, see http://www.eso.org/sci/meetings/2019/4MOST.htm
The sixth data release of the Radial Velocity Experiment (RAVE) -- II:stellar atmospheric parameters, chemical abundances and distances
We present part 2 of the 6th and final Data Release (DR6 or FDR) of the
Radial Velocity Experiment (RAVE), a magnitude-limited (9<I<12) spectroscopic
survey of Galactic stars randomly selected in the southern hemisphere. The RAVE
medium-resolution spectra (R~7500) cover the Ca-triplet region (8410-8795A) and
span the complete time frame from the start of RAVE observations on 12 April
2003 to their completion on 4 April 2013. In the second of two publications, we
present the data products derived from 518387 observations of 451783 unique
stars using a suite of advanced reduction pipelines focussing on stellar
atmospheric parameters, in particular purely spectroscopically derived stellar
atmospheric parameters (Teff, log(g), and the overall metallicity), enhanced
stellar atmospheric parameters inferred via a Bayesian pipeline using Gaia DR2
astrometric priors, and asteroseismically calibrated stellar atmospheric
parameters for giant stars based on asteroseismic observations for 699 K2
stars. In addition, we provide abundances of the elements Fe, Al, and Ni, as
well as an overall [alpha/Fe] ratio obtained using a new pipeline based on the
GAUGUIN optimization method that is able to deal with variable signal-to-noise
ratios. The RAVE DR6 catalogs are cross matched with relevant astrometric and
photometric catalogs, and are complemented by orbital parameters and effective
temperatures based on the infrared flux method. The data can be accessed via
the RAVE Web site (http://rave-survey.org) or the Vizier database.Comment: 65 pages, 33 figures, accepted for publication to A
The Sixth Data Release of the Radial Velocity Experiment (R ave). II. Stellar Atmospheric Parameters, Chemical Abundances, and Distances
We present part 2 of the sixth and final Data Release (DR6) of the Radial Velocity Experiment (Rave), a magnitude-limited spectroscopic survey of Galactic stars randomly selected in Earth's southern hemisphere. The Rave medium-resolution spectra (R ⌠7500) cover the Ca triplet region (8410-8795 Ă
) and span the complete time frame from the start of Rave observations on 2003 April 12 to their completion on 2013 April 4. In the second of two publications, we present the data products derived from 518,387 observations of 451,783 unique stars using a suite of advanced reduction pipelines focusing on stellar atmospheric parameters, in particular purely spectroscopically derived stellar atmospheric parameters, and the overall metallicity), enhanced stellar atmospheric parameters inferred via a Bayesian pipeline using Gaia DR2 astrometric priors, and asteroseismically calibrated stellar atmospheric parameters for giant stars based on asteroseismic observations for 699 K2 stars. In addition, we provide abundances of the elements Fe, Al, and Ni, as well as an overall [α/Fe] ratio obtained using a new pipeline based on the GAUGUIN optimization method that is able to deal with variable signal-to-noise ratios. The Rave DR6 catalogs are cross-matched with relevant astrometric and photometric catalogs, and are complemented by orbital parameters and effective temperatures based on the infrared flux method. The data can be accessed via the Rave website (http://rave-survey.org) or the Vizier database
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