41,627 research outputs found
R-Band Imaging of Fields Around 1<z<2 Radiogalaxies
We have taken deep -band images of fields around five radiogalaxies:
0956+47, 1217+36, 3C256, 3C324 and 3C294 with . 0956+47 is found to
show a double nucleus. Our data on 1217+36 suggest the revision of its
classification as a radiogalaxy. We found a statistically significant excess of
bright () galaxies on scales of 2 arcmin around the radiogalaxies
(which have ) in our sample. The excess has been determined
empirically to be at level. It is remarkable that this excess
is not present for galaxies within the same area, suggesting that
the excess is not physically associated to the galaxies but due to intervening
groups and then related to gravitational lensing.Comment: 20 pages, uuencoded compressed PostScript including tables. Figures
available upon request. To appear in the March 1995 issue of The Astronomical
Journa
Global analysis of the negative parity non-strange baryons in the 1/Nc expansion
A global study of the negative parity non-strange baryon observables is
performed in the frame- work of the 1/Nc expansion. Masses, partial decay
widths and photo-couplings are simultaneously analyzed. A main objective is to
determine the composition of the spin 1/2 and 3/2 nucleon states, which come in
pairs and involve two mixing angles which can be determined and tested for
consistency by the mentioned observables. The issue of the assignment of those
nucleon states to the broken SU(4) x O(3) mixed-symmetry multiplet is studied
in detail, with the conclusion that the assignment made in the old studies
based on the non-relativistic quark model is the preferred one. In addition,
the analysis involves an update of the input data with respect to previous
works.Comment: 30 pages, 3 figure
Quasar-galaxy associations revisited
Gravitational lensing predicts an enhancement of the density of bright,
distant QSOs around foreground galaxies. We measure this QSO-galaxy correlation
w_qg for two complete samples of radio-loud quasars, the southern 1Jy and
Half-Jansky samples. The existence of a positive correlation between z~1
quasars and z~0.15 galaxies is confirmed at a p=99.0% significance level
(>99.9%) if previous measurements on the northern hemisphere are included). A
comparison with the results obtained for incomplete quasar catalogs (e.g. the
Veron-Cetty and Veron compilation) suggests the existence of an `identification
bias', which spuriously increases the estimated amplitude of the quasar-galaxy
correlation for incomplete samples. This effect may explain many of the
surprisingly strong quasar-galaxy associations found in the literature.
Nevertheless, the value of w_qg that we measure in our complete catalogs is
still considerably higher than the predictions from weak lensing. We consider
two effects which could help to explain this discrepancy: galactic dust
extinction and strong lensing.Comment: 9 pages, 6 figures, MNRAS accepte
Two and three electrons in a quantum dot: 1/|J| - expansion
We consider systems of two and three electrons in a two-dimensional parabolic
quantum dot. A magnetic field is applied perpendicularly to the electron plane
of motion. We show that the energy levels corresponding to states with high
angular momentum, J, and a low number of vibrational quanta may be
systematically computed as power series in 1/|J|. These states are relevant in
the high-B limit.Comment: LaTeX, 15 pages,6 postscript figure
Diagnostic accuracy of a brief screening tool forAttention Deficit/Hyperactivity Disorder in UK prison inmates
BackgroundAttention deficit hyperactivity disorder (ADHD) is overrepresented in prison, making it imperative to identify a screening tool that can be quickly applied to efficiently detect the disorder. We explored the discrimination ability of a widely used ADHD screen, the Barkley Adult ADHD Rating Scale (BAARS-IV), against a clinical diagnostic interview. A brief version of the screen was then developed in order to simplify its use in the prison context, and maximize its diagnostic properties.MethodA cross-sectional study of 390 male prison inmates was performed in the UK, all participants were screened and interviewed via the Diagnostic Interview for ADHD in Adults 2.0 (DIVA-2).ResultsA total of 47 (12.1%) inmates screened positive for ADHD using the full BAARS-IV, and 96 (24.6%) were clinically diagnosed, for a sensitivity of 37.9 and a specificity of 96.3. Our models identified the six items that most predicted ADHD diagnosis, with adjusted odds ratios ranging from 2.66 to 4.58. Sensitivity, specificity and accuracy were 0.82, 0.84 and 0.84, respectively, for the developed brief scale, and 0.71, 0.85 and 0.81 for its validation. Weighted probability scores produced an area under the curve of 0.89 for development, and 0.82 for validation of the brief scale.ConclusionsThe original BAARS-IV performed poorly at identifying prison inmates with ADHD. Our developed brief scale substantially improved diagnostic accuracy. The brief screening instrument has great potential to be used as an accurate and resource-effective tool to screen young people and adults for likely ADHD in the criminal justice system.</jats:sec
Kinematics of Current Region Fragmentation in Semi-Inclusive Deeply Inelastic Scattering
Different kinematical regimes of semi-inclusive deeply inelastic scattering
(SIDIS) processes correspond to different underlying partonic pictures, and it
is important to understand the transition between them. This is particularly
the case when there is sensitivity to intrinsic transverse momentum, in which
case kinematical details can become especially important. We address the
question of how to identify the current fragmentation region --- the
kinematical regime where a factorization picture with fragmentation functions
is appropriate. We distinguish this from soft and target fragmentation regimes.
Our criteria are based on the kinematic regions used in derivations of
factorization theorems. We argue that, when hard scales are of order a few
GeVs, there is likely significant overlap between different rapidity regions
that are normally understood to be distinct. We thus comment on the need to
take this into account with more unified descriptions of SIDIS, which should
span all rapidities for the produced hadron. Finally, we propose general
criteria for estimating the proximity to the current region at large Q.Comment: 9 Pages, 5 figures; minor clarifications and corrections, version
appearing in Physics Letters
3D molecular line formation in dwarf carbon-enhanced metal-poor stars
We present a detailed analysis of the carbon and nitrogen abundances of two
dwarf carbon-enhanced metal-poor (CEMP) stars: SDSS J1349-0229 and SDSS
J0912+0216. We also report the oxygen abundance of SDSS J1349-0229. These stars
are metal-poor, with [Fe/H] < -2.5, and were selected from our ongoing survey
of extremely metal-poor dwarf candidates from the Sloan Digital SkySurvey
(SDSS). The carbon, nitrogen and oxygen abundances rely on molecular lines
which form in the outer layers of the stellar atmosphere. It is known that
convection in metal-poor stars induces very low temperatures which are not
predicted by `classical' 1D stellar atmospheres. To obtain the correct
temperature structure, one needs full 3D hydrodynamical models. Using CO5BOLD
3D hydrodynamical model atmospheres and the Linfor3D line formation code,
molecular lines of CH, NH, OH and C2 were computed, and 3D carbon, nitrogen and
oxygen abundances were determined. The resulting carbon abundances were
compared to abundances derived using atomic CI lines in 1D LTE and NLTE. There
is not a good agreement between the carbon abundances determined from C2 bands
and from the CH band, and molecular lines do not agree with the atomic CI
lines. Although this may be partly due to uncertainties in the transition
probabilities of the molecular bands it certainly has to do with the
temperature structure of the outer layers of the adopted model atmosphere. We
explore the influence of the 3D model properties on the molecular abundance
determination. In particular, the choice of the number of opacity bins used in
the model calculations and its subsequent effects on the temperature structure
and molecular line formation is discussed. (Abridged)Comment: Poster presented at IAU JD 10, Rio de Janeiro, 10-11 August 2009,
published in Memorie della Societa' Astronomica Italiana, Vol. 80 n.3 P.735.
One reference corrected, matches the published versio
Anveshak - A Groundtruth Generation Tool for Foreground Regions of Document Images
We propose a graphical user interface based groundtruth generation tool in
this paper. Here, annotation of an input document image is done based on the
foreground pixels. Foreground pixels are grouped together with user interaction
to form labeling units. These units are then labeled by the user with the user
defined labels. The output produced by the tool is an image with an XML file
containing its metadata information. This annotated data can be further used in
different applications of document image analysis.Comment: Accepted in DAR 201
Ultrasound attenuation and a P-B-T phase diagram of superfluid 3He in 98% aerogel
Longitudinal sound attenuation measurements in superfluid 3He in 98% aerogel
were conducted at pressures between 14 and 33 bar and in magnetic fields up to
4.44 kG. The temperature dependence of the ultrasound attenuation in the A-like
phase was determined for the entire superfluid region exploiting the field
induced meta-stable A-like phase at the highest field. In the lower field, the
A-B transition in aerogel was identified by a smooth jump in attenuation on
both cooling and warming. Based on the transitions observed on warming, a phase
diagram as a function of pressure (P), temperature (T) and magnetic field (B)
is constructed. We find that the A-B phase boundary in aerogel recedes in a
drastically different manner than in bulk in response to an increasing magnetic
field. The implications of the observed phase diagram are discussed.Comment: 9 pages, 13 figures, accepted to PR
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