6,924 research outputs found
Are optically-selected QSO catalogs biased ?
A thorough study of QSO-galaxy correlations has been done on a region close
to the North Galactic Pole using a complete subsample of the optically selected
CFHT/MMT QSO survey and the galaxy catalog of Odewahn and Aldering (1995).
Although a positive correlation between bright QSOs and galaxies is expected
because of the magnification bias effect, none is detected. On the contrary,
there is a significant (>99.6%) anticorrelation between z<1.6 QSOs and red
galaxies on rather large angular distances. This anticorrelation is much less
pronounced for high redshift z>1.6 QSOs, which seems to exclude dust as a cause
of the QSO underdensity. This result suggests that the selection process
employed in the CFHT/MMT QSO survey is losing up to 50% of low redshift z<1.6
QSOs in regions of high galaxy density. The incompleteness in the whole z<1.6
QSO sample may reach 10% and have important consequences in the estimation of
QSO evolution and the QSO autocorrelation function.Comment: 17 pages LaTeX (aasms4), plus 6 EPS figures. To be published in the
Astronomical Journa
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
Expression and cellular localization of the transcription factor NeuroD1 in the developing and adult rat pineal gland
Circadian rhythms govern many aspects of mammalian physiology. The daily pattern of melatonin synthesis and secretion is one of the classic examples of circadian oscillations. It is mediated by a class of neuroendocrine cells known as pinealocytes which are not yet fully defined. An established method to evaluate functional and cytological characters is through the expression of lineageâspecific transcriptional regulators. NeuroD1 is a basic helixâloopâhelix transcription factor involved in the specification and maintenance of both endocrine and neuronal phenotypes. We have previously described developmental and adult regulation of NeuroD1 mRNA in the rodent pineal gland. However, the transcript levels were not influenced by the elimination of sympathetic input, suggesting that any rhythmicity of NeuroD1 might be found downstream of transcription. Here, we describe NeuroD1 protein expression and cellular localization in the rat pineal gland during development and the daily cycle. In embryonic and perinatal stages, protein expression follows the mRNA pattern and is predominantly nuclear. Thereafter, NeuroD1 is mostly found in pinealocyte nuclei in the early part of the night and in cytoplasm during the day, a rhythm maintained into adulthood. Additionally, nocturnal nuclear NeuroD1 levels are reduced after sympathetic disruption, an effect mimicked by the in vivo administration of αâ and ÎČâadrenoceptor blockers. NeuroD1 phosphorylation at two sites, Ser274 and Ser336, associates with nuclear localization in pinealocytes. These data suggest that NeuroD1 influences pineal phenotype both during development and adulthood, in an autonomic and phosphorylationâdependent manner.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111177/1/jpi12228.pd
The Effects of Patient-Centered Depression Care on Patient Satisfaction and Depression Remission
Background: While health systems are striving for patient-centered care, they have little evidence to guide them on how to engage patients in their care, or how this may affect patient experiences and outcomes. Objective: To explore which specific patient-centered aspects of care were best associated with depression improvement and care satisfaction. Methods: Design - observational. Setting - 83 primary care clinics across Minnesota. Subjects - Primary care patients with new prescriptions for antidepressants for depression were recruited from 2007 to 2009. Outcome measures - Patients completed phone surveys regarding demographics and self-rated health status and depression severity at baseline and 6 months. Patient centeredness was assessed via a modified version of the Patient Assessment of Chronic Illness Care. Differences in rates of remission and satisfaction between positive and negative responses for each care process were evaluated using chi-square tests. Results: At 6 months, 37% of 792 patients ages 18â88 achieved depression remission, and 79% rated their care as good-to-excellent. Soliciting patient preferences for care and questions or concerns, providing treatment plans, utilizing depression scales and asking about suicide risk were patient centered measures that were positively associated with depression remission in the unadjusted model; these associations were mildly weakened after adjustment for depression severity and health status. Nearly all measures of patient centeredness were positively associated with care ratings. Conclusion: The patient centeredness of care influences how patients experience and rate their care. This study identified specific actions providers can take to improve patient satisfaction and depression outcomes
Biogenic Nitrogen Gas Production at the OxicâAnoxic Interface in the Cariaco Basin, Venezuela
Excess nitrogen gas (N2xs) was measured in samples collected at six locations in the eastern and western sub-basins of the Cariaco Basin, Venezuela, in September 2008 (non-upwelling conditions) and March 2009 (upwelling conditions). During both sampling periods, N2xs concentrations were below detection in surface waters, increasing to ~ 22 ÎŒmol N kgâ1 at the oxicâanoxic interface ([O2] \u3c ~ 4 ÎŒmol kgâ1, ~ 250 m). Below the oxicâanoxic interface (300â400 m), the average concentration of N2xs was 24.7 ± 1.9 ÎŒmol N kgâ1 in September 2008 and 27.5 ± 2.0 ÎŒmol N kgâ1 in March 2009, i.e., N2xs concentrations within this depth interval were ~ 3 ÎŒmol N kgâ1 higher (p \u3c 0.001) during the upwelling season compared to the non-upwelling period. These results suggest that N-loss in the Cariaco Basin may vary seasonally in response to changes in the flux of sinking particulate organic matter. We attribute the increase in N2xs concentrations, or N-loss, observed during upwelling to: (1) higher availability of fixed nitrogen derived from suspended and sinking particles at the oxicâanoxic interface and/or (2) enhanced ventilation at the oxicâanoxic interface during upwelling
Deep Imaging of AXJ2019+112: The Luminosity of a ``Dark Cluster''
We detect a distant cluster of galaxies centered on the QSO lens and luminous
X-ray source AXJ2019+112, a.k.a. ``The Dark Cluster'' (Hattori et al 1997).
Using deep V,I Keck images and wide-field K_s imaging from the NTT, a tight red
sequence of galaxies is identified within a radius of 0.2 h^{-1} Mpc of the
known z=1.01 elliptical lensing galaxy. The sequence, which includes the
central elliptical galaxy, has a slope in good agreement with the model
predictions of Kodama et al (1998) for z~1. We estimate the integrated
rest-frame luminosity of the cluster to be L_V > 3.2 x 10^{11}h^{-2}L_{\sun}
(after accounting for significant extinction at the low latitude of this
field), more than an order of magnitude higher than previous estimates. The
central region of the cluster is deconvolved using the technique of Magain,
Courbin & Sohy (1998), revealing a thick central arc coincident with an
extended radio source. All the observed lensing features are readily explained
by differential magnification of a radio loud AGN by a shallow elliptical
potential. The QSO must lie just outside the diamond caustic, producing two
images, and the arc is a highly magnified image formed from a region close to
the center of the host galaxy, projecting inside the caustic. The
mass--to--light ratio within an aperture of 0.4 h ^{-1} Mpc is M_x/L_V=
224^{+112}_{-78}h(M/L_V)_{\sun}, using the X-ray temperature. The strong lens
model yields a compatible value, M/L_V= 372^{+94}_{-94}h(M/L_V)_{\sun}, whereas
an independent weak lensing analysis sets an upper limit of M/L_V <520
h(M/L_V)_{\sun}, typical of massive clusters.Comment: AAS Latex format, 24 pages, 9 figures. Fig 1a,b available at
http://astro.berkeley.edu/~benitezn/cluster.html . Submitted to ApJ on August
15t
The AMS-02 RICH Imager Prototype - In-Beam Tests with 20 GeV/c per Nucleon Ions -
A prototype of the AMS Cherenkov imager (RICH) has been tested at CERN by
means of a low intensity 20 GeV/c per nucleon ion beam obtained by
fragmentation of a primary beam of Pb ions. Data have been collected with a
single beam setting, over the range of nuclear charges 2<Z<~45 in various beam
conditions and using different radiators. The charge Z and velocity beta
resolutions have been measured.Comment: 4 pages, contribution to the ICRC 200
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