355 research outputs found
Imaging and spectroscopy of galaxies associated with two z~0.7 damped Lyman-alpha absorption systems
We have identified galaxies near two quasars which are at the redshift of
damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both
galaxies are actively forming stars. One galaxy has a luminosity close to the
break in the local galaxy luminosity function, L*, the other is significantly
fainter than L* and appears to be interacting with a nearby companion. Despite
the strong selection effects favoring spectroscopic identification of the most
luminous DLA galaxies, many of the spectroscopically-identified DLA galaxies in
the literature are sub-L*, suggesting that the majority of the DLA population
is probably sub-L*, in contrast to MgII absorbers at similar redshifts whose
mean luminosity is close to L*.Comment: 9 pages, to appear in AJ, November 2003 issu
The Reddest Quasars
In a survey of quasar candidates selected by matching the FIRST and 2MASS
catalogs, we have found two extraordinarily red quasars. FIRST J013435.7-093102
is a 1 Jy source at z=2.216 and has B-K > 10, while FIRST J073820.1+275045 is a
2.5 mJy source at z=1.985 with B-K = 8.4. FIRST J073820.1+275045 has strong
absorption lines of MgII and CIV in the rest frame of the quasar and is highly
polarized in the rest frame ultraviolet, strongly favoring the interpretation
that its red spectral energy distribution is caused by dust reddening local to
the quasar. FIRST J073820.1+275045 is thus one of the few low radio-luminosity,
highly dust-reddened quasars known. The available observational evidence for
FIRST J013435.7-093102 leads us to conclude that it too is reddened by dust. We
show that FIRST J013435.7-093102 is gravitationally lensed, increasing the
number of known lensed, extremely dust-reddened quasars to at least three,
including MG0414-0534 and PKS1830-211. We discuss the implications of whether
these objects are reddened by dust in the host or lensing galaxies. If reddened
by their local environment, then we estimate that between 10 and 20% of the
radio-loud quasar population is reddened by dust in the host galaxy. The
discovery of FIRST J073820.1+275045 and objects now emerging from X-ray surveys
suggests the existence of an analogous radio-quiet red quasar population. Such
objects will be entirely missed by standard radio or optical quasar surveys. If
dust in the lensing galaxies is primarily responsible for the extreme redness
of the lensed quasars, then an untold number of gravitationally lensed quasars
are being overlooked.Comment: AASTEX 24 pp., 7 figs; accepted by ApJ. See also the preprint
astro-ph/0107435 by Winn et al., who independently discovered that
J013435.7-093102 is gravitationally lense
Social Genomics of Healthy and Disordered Internet Gaming
Objectives: To combine social genomics with cultural approaches to expand understandings of the somatic health dynamics of online gaming, including in the controversial nosological construct of internet gaming disorder (IGD).
Methods: In blood samples from 56 U.S. gamers, we examined expression of the conserved transcriptional response to adversity (CTRA), a leukocyte gene expression profile activated by chronic stress. We compared positively engaged and problem gamers, as identified by an ethnographically developed measure, the Positive and Negative Gaming Experiences Scale (PNGE-42), and also by a clinically derived IGD scale (IGDS-SF9).
Results: CTRA profiles showed a clear relationship with PNGE-42, with a substantial linkage to offline social support, but were not meaningfully associated with disordered play as measured by IGDS-SF9.
Conclusions: Our study advances understanding of the psychobiology of play, demonstrating via novel transcriptomic methods the association of negatively experienced internet play with biological measures of chronic threat, uncertainty, and distress. Our findings are consistent with the view that problematic patterns of online gaming are a proxy for broader patterns of biopsychosocial stress and distress such as loneliness, rather than a psychiatric disorder sui generis, which might exist apart from gamers ’ other life problems. By confirming the biological correlates of certain patterns of internet gaming, culturally-sensitive genomics approaches such as this can inform both evolutionary theorizing regarding the nature of play, as well as current psychiatric debates about the appropriateness of modeling distressful gaming on substance addiction and problem gambling
XMM-Newton Detection of the Rare FR II BAL Quasar FIRST J101614.3+520916
We have detected FIRST J101614.3+520916 with the XMM-Newton X-ray
Observatory. FIRST J101614.3+520916, one of the most extreme radio-loud, broad
absorption line (BAL) quasars so far discovered, is also a Fanaroff-Riley type
II (FR II) radio source. We find that, compared to its estimated intrinsic
X-ray flux, the observed X-rays are likely suppressed, and that the observed
hardness ratio indicates significant soft X-ray photons. This is inconsistent
with the simplest model, a normal quasar spectrum absorbed by a large neutral
HI column density, which would primarily absorb the softer photons. More
complex models, involving partial covering, an ionized absorber, ionized mirror
reflection, or jet contributions need to be invoked to explain this source. The
suppressed but soft X-ray emission in this radio-loud BAL quasar is consistent
with the behavior displayed by other BAL quasars, both radio-loud and
radio-quiet.Comment: 5 pages, 2 figures. Accepted in AJ. (Typos corrected.
Reverberation Mapping of the Kepler-Field AGN KA1858+4850
KA1858+4850 is a narrow-line Seyfert 1 galaxy at redshift 0.078 and is among
the brightest active galaxies monitored by the Kepler mission. We have carried
out a reverberation mapping campaign designed to measure the broad-line region
size and estimate the mass of the black hole in this galaxy. We obtained 74
epochs of spectroscopic data using the Kast Spectrograph at the Lick 3-m
telescope from February to November of 2012, and obtained complementary V-band
images from five other ground-based telescopes. We measured the H-beta light
curve lag with respect to the V-band continuum light curve using both
cross-correlation techniques (CCF) and continuum light curve variability
modeling with the JAVELIN method, and found rest-frame lags of lag_CCF = 13.53
(+2.03, -2.32) days and lag_JAVELIN = 13.15 (+1.08, -1.00) days. The H-beta
root-mean-square line profile has a width of sigma_line = 770 +/- 49 km/s.
Combining these two results and assuming a virial scale factor of f = 5.13, we
obtained a virial estimate of M_BH = 8.06 (+1.59, -1.72) x 10^6 M_sun for the
mass of the central black hole and an Eddington ratio of L/L_Edd ~ 0.2. We also
obtained consistent but slightly shorter emission-line lags with respect to the
Kepler light curve. Thanks to the Kepler mission, the light curve of
KA1858+4850 has among the highest cadences and signal-to-noise ratios ever
measured for an active galactic nucleus; thus, our black hole mass measurement
will serve as a reference point for relations between black hole mass and
continuum variability characteristics in active galactic nuclei
Regulated Expression of Chromobox Homolog 5 Revealed in Tumors of ApcMin/+ ROSA11 Gene Trap Mice
The gene-trap lacZ reporter insertion, ROSA11, in the Cbx5 mouse gene illuminates the regulatory complexity of this locus in ApcMin/+ mice. The insertion site of the β-Geo gene-trap element lies in the 24-kb intron proximal to the coding region of Cbx5. Transcript analysis indicates that two promoters for Cbx5 flank this insertion site. Heterozygotes for the insertion express lacZ widely in fetal tissues but show limited expression in adult tissues. In the intestine, strong expression is limited to proliferative zones of crypts and tumors. Homozygotes for ROSA11, found at a lower than Mendelian frequency, express reduced levels of the coding region transcript in normal tissues, using a downstream promoter. Analysis via real-time polymerase chain reaction indicates that the upstream promoter is the dominant promoter in normal epithelium and tumors. Bioinformatic analysis of the Cbx5 locus indicates that WNT and its target transcription factor MYC can establish a feedback loop that may play a role in regulating the self-renewal of the normal intestinal epithelium and its tumors
Star formation suppression in compact group galaxies: A new path to quenching?
We present CO(1-0) maps of 12 warm H2-selected Hickson Compact Groups (HCGs), covering 14 individually imaged warm H2 bright galaxies, with the Combined Array for Research in Millimeter Astronomy. We found a variety of molecular gas distributions within the HCGs, including regularly rotating disks, bars, rings, tidal tails, and possibly nuclear outflows, though the molecular gas morphologies are more consistent with spirals and early-type galaxies than mergers and interacting systems. Our CO-imaged HCG galaxies, when plotted on the Kennicutt-Schmidt relation, shows star formation (SF) suppression of distributed bimodally, with five objects exhibiting suppressions of 10 and depletion timescales 10 Gyr. This SF inefficiency is also seen in the efficiency per freefall time of Krumholz et al. We investigate the gas-to-dust ratios of these galaxies to determine if an incorrect LCO-M(H2) conversion caused the apparent suppression and find that HCGs have normal gas-to-dust ratios. It is likely that the cause of the apparent suppression in these objects is associated with shocks injecting turbulence into the molecular gas, supported by the fact that the required turbulent injection luminosity is consistent with the bright H2 luminosity reported by Cluver et al. Galaxies with high SF suppression ( 10) also appear to be those in the most advanced stages of transition across both optical and infrared color space. This supports the idea that at least some galaxies in HCGs are transitioning objects, where a disruption of the existing molecular gas in the system suppresses SF by inhibiting the molecular gas from collapsing and forming stars efficiently. These observations, combined with recent work on poststarburst galaxies with molecular reservoirs, indicates that galaxies do not need to expel their molecular reservoirs prior to quenching SF and transitioning from blue spirals to red early-type galaxies. This may imply that SF quenching can occur without the need to starve a galaxy of cold gas first
Persistence of apoptotic cells without autoimmune disease or inflammation in CD14−/− mice
Interaction of macrophages with apoptotic cells involves multiple steps including recognition, tethering, phagocytosis, and anti-inflammatory macrophage responses. Defective apoptotic cell clearance is associated with pathogenesis of autoimmune disease. CD14 is a surface receptor that functions in vitro in the removal of apoptotic cells by human and murine macrophages, but its mechanism of action has not been defined. Here, we demonstrate that CD14 functions as a macrophage tethering receptor for apoptotic cells. Significantly, CD14−/− macrophages in vivo are defective in clearing apoptotic cells in multiple tissues, suggesting a broad role for CD14 in the clearance process. However, the resultant persistence of apoptotic cells does not lead to inflammation or increased autoantibody production, most likely because, as we show, CD14−/− macrophages retain the ability to generate anti-inflammatory signals in response to apoptotic cells. We conclude that CD14 plays a broad tethering role in apoptotic cell clearance in vivo and that apoptotic cells can persist in the absence of proinflammatory consequences
Characterizing Nature and Participant Experience in Studies of Nature Exposure for Positive Mental Health: An Integrative Review
A growing number of studies demonstrate significant associations between nature experiences and positive mental health outcomes (e.g., improved mood, decreased stress). However, implementation of this research by practitioners in fields such as urban design or public health has been limited. One reason for this is that it remains unclear what elements of nature and types of participant experience are consistently associated with mental health benefits. As a result, decision-makers who aim to enhance mental health in cities have little guidance about which elements of nature and types of experiences in natural areas may lead to positive mental health outcomes. We reviewed 30 studies with 41 distinct exposures in nature that elicited positive mental health benefits and characterized the elements of nature found at these sites, as well as aspects of participants’ experience. Elements of natural areas considered include: forest, managed grass, and water as dominant land cover types, specific water features (e.g., small ponds, fountains) and built features (e.g., trails, paths). The majority of the studies we reviewed assessed the experiences of individuals (vs. in groups) participating in walks during warmer seasons. Most studies did not describe the “nature of the nature” associated with positive mental health outcomes. We contacted authors and used Google Earth imagery to reconstruct the specific natural elements, landscape typology, and site adjacencies present in past studies. We recommend specific ways researchers could better and more transparently document important elements of nature and participant experience in study design and reporting that will enhance the planning and design relevance of their work
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