2,387 research outputs found
Possible Local Spiral Counterparts to Compact Blue Galaxies at Intermediate Redshift
We identify nearby disk galaxies with optical structural parameters similar
to those of intermediate-redshift compact blue galaxies. By comparing HI and
optical emission-line widths, we show that the optical widths substantially
underestimate the true kinematic widths of the local galaxies. By analogy,
optical emission-line widths may underrepresent the masses of intermediate-z
compact objects. For the nearby galaxies, the compact blue morphology is the
result of tidally-triggered central star formation: we argue that interactions
and minor mergers may cause apparently compact morphology at higher redshift.Comment: 5 pages, uses emulateapj5 and psfig. To appear in ApJ
Forming Young Bulges within Existing Disks: Statistical Evidence for External Drivers
Contrary to traditional models of galaxy formation, recent observations
suggest that some bulges form within preexisting disk galaxies. Such late-epoch
bulge formation within disks seems to be linked to disk gas inflow and central
star formation, caused by either internal secular processes or galaxy mergers
and interactions. We identify a population of galaxies likely to be
experiencing active bulge growth within disks, using the criterion that the
color within the half-light radius is bluer than the outer disk color. Such
blue-centered galaxies make up >10% of star-forming disk galaxies within the
Nearby Field Galaxy Survey, a broad survey designed to represent the natural
diversity of the low-z galaxy population over a wide range of luminosities and
environments. Blue-centered galaxies correlate at 99% confidence with
morphological peculiarities suggestive of minor mergers and interactions. From
this and other evidence, we argue that external drivers rather than internal
secular processes probably account for the majority of blue-centered galaxies.
We go on to discuss quantitative plausibility arguments indicating that
blue-centered evolutionary phases may represent an important mode of bulge
growth for most disk galaxies, leading to significant changes in bulge-to-disk
ratio without destroying disks. If this view is correct, bulge growth within
disks may be a natural consequence of the repeated galaxy mergers and
interactions inherent in hierarchical galaxy formation.Comment: 18 pages including 12 figures, AJ, accepte
The Tully-Fisher Relation as a Measure of Luminosity Evolution: A Low Redshift Baseline for Evolving Galaxies
We use optical rotation curves to investigate the R-band Tully-Fisher
properties of a sample of 90 spiral galaxies in close pairs. The galaxies
follow the Tully-Fisher relation remarkably well, with the exception of eight
distinct 3-sigma outliers. Although most of the outliers show signs of recent
star formation, gasdynamical effects are probably the dominant cause of their
anomalous Tully-Fisher properties. Four outliers with small emission line
widths have very centrally concentrated line emission and truncated rotation
curves; the central emission indicates recent gas infall after a close
galaxy-galaxy pass. These four galaxies may be local counterparts to compact,
blue galaxies at intermediate redshift. The remaining galaxies have a
negligible offset from the reference Tully-Fisher relation, but a shallower
slope (2.6-sigma significance) and a 25% larger scatter. We characterize the
non-outlier sample with measures of distortion and star formation to search for
third parameter dependence in the residuals of the TF relation. Severe
kinematic distortion is the only significant predictor of TF residuals; this
distortion is not, however, responsible for the slope difference from the
reference distribution.
Because the outliers are easily removed by sigma clipping, we conclude that
even in the presence of some tidal distortion, detection of moderate luminosity
evolution should be possible with high-redshift samples the size of this
90-galaxy study. (Abridged.)Comment: LaTeX document, 55 pages including 18 figures, to appear in A
Close Galaxy Counts as a Probe of Hierarchical Structure Formation
Standard LCDM predicts that the major merger rate of galaxy-size dark matter
halos rises rapidly with redshift. The average number of close companions per
galaxy, Nc, is often used to infer the galaxy merger rate, however, recent
observational studies suggest that Nc evolves very little with redshift. Here
we use a "hybrid" N- body simulation plus analytic substructure model to
predict Nc directly. We identify dark matter subhalos with galaxies and show
that the observed lack of close pair count evolution arises because the high
merger rate per halo at early times is counteracted by a decrease in the number
of halos massive enough to host a galaxy pair. We compare our results to data
compiled from the DEEP2, SSRS2, and the UZC redshift surveys. Observed pair
counts match our predictions if we assume a monotonic mapping between galaxy
luminosity and the maximum circular velocity that each subhalo had when it was
first accreted onto its host halo. This suggests that satellite galaxies are
significantly more resilient to destruction than are dissipationless dark
matter subhalos. We argue that while Nc does not provide a direct measure of
the halo merger rate, it offers a powerful means to constrain the Halo
Occupation Distribution and the spatial distribution of galaxies within halos.
Interpreted in this way, close pair counts provide a useful test of galaxy
formation processes on < 100 kpc scales.Comment: 16 pages, 16 figures, minor change to figure 10, figure captions
updated, typos corrected, Figure 4 corrected, version accepted for
publication by Ap
First Trimester Prediction of Uteroplacental Disease- Results of the Prospective Handle Study
To assess the ability of non-invasive cardiac output monitoring (NICOM), a novel method of non-invasive maternal hemodynamic assessment using bioreactance, in combination with first trimester biomarkers to predict the evolution of gestational hypertension (GH), pre-eclampsia (PE) and normotensive fetal growth restriction (FGR)
Pre-surgical depression and anxiety and recovery following coronary artery bypass graft surgery
We aimed to explore the combined contribution of pre-surgical depression and anxiety symptoms for recovery following coronary artery bypass graft (CABG) using data from 251 participants. Participants were assessed prior to surgery for depression and anxiety symptoms and followed up at 12 months to assess pain and physical symptoms, while hospital emergency admissions and death/major adverse cardiac events (MACE) were monitored on average 2.68 years after CABG. After controlling for covariates, baseline anxiety symptoms, but not depression, were associated with greater pain (ÎČ = 0.231, p = 0.014) and greater physical symptoms (ÎČ = 0.194, p = 0.034) 12 months after surgery. On the other hand, after controlling for covariates, baseline depression symptoms, but not anxiety, were associated with greater odds of having an emergency admission (OR 1.088, CI 1.010â1.171, p = 0.027) and greater hazard of death/MACE (HR 1.137, CI 1.042â1.240, p = 0.004). These findings point to different pathways linking mood symptoms with recovery after CABG surgery
Cardiovascular Health in Anxiety or Mood Problems Study (CHAMPS): study protocol for a randomized controlled trial
Background: Previous psychological and pharmacological interventions have primarily focused on depression disorders in populations with cardiovascular diseases (CVDs) and the efficacy of anxiety disorder interventions is only more recently being explored. Transdiagnostic interventions address common emotional processes and the full range of anxiety and depression disorders often observed in populations with CVDs. The aim of CHAMPS is to evaluate the feasibility of a unified protocol (UP) for the transdiagnostic treatment of emotional disorders intervention in patients recently hospitalized for CVDs. The current study reports the protocol of a feasibility randomized controlled trial to inform a future trial. Methods/Design: This is a feasibility randomized, controlled trial with a single-center design. A total of 50 participants will be block-randomized to either a UP intervention or enhanced usual care. Both groups will receive standard CVD care. The UP intervention consists of 1) enhancing motivation, readiness for change, and treatment engagement; (2) psychoeducation about emotions; (3) increasing present focused emotion awareness; (4) increasing cognitive flexibility; (5) identifying and preventing patterns of emotion avoidance and maladaptive emotion-driven behaviors (EDBs, including tobacco smoking, and alcohol use); (6) increasing tolerance of emotion-related physical sensations; (7) interoceptive and situation-based emotion-focused exposure; and (8) relapse prevention strategies. Treatment duration is 12 to 18Â weeks. Relevant outcomes include the standard deviation of self-rated anxiety, depression and quality of life symptoms. Other outcomes include intervention acceptability, satisfaction with care, rates of EDBs, patient adherence, physical activity, cardiac and psychiatric readmissions. Parallel to the main trial, a nonrandomized comparator cohort will be recruited comprising 150 persons scoring below the predetermined depression and anxiety severity thresholds. Discussion: CHAMPS is designed to evaluate the UP for the transdiagnostic treatment of emotional disorders targeting emotional disorder processes in a CVD population. The design will provide preliminary evidence of feasibility, attrition, and satisfaction with treatment to design a definitive trial. If the trial is feasible, it opens up the possibility for interventions to target broader emotional processes in the precarious population with CVD and emotional distress.Phillip J. Tully, Deborah A. Turnbull, John D. Horowitz, John F. Beltrame, Terina Selkow, Bernhard T. Baune, Elizabeth Markwick, Shannon Sauer-Zavala, Harald Baumeister, Suzanne Cosh and Gary A. Witter
Pregnancy-specific stress, fetoplacental haemodynamics, and neonatal outcomes in women with small for gestational age pregnancies: a secondary analysis of the multicentre Prospective Observational Trial to Optimise Paediatric Health in Intrauterine Growth Restriction
Objectives: To examine associations between maternal pregnancy-specific stress and umbilical (UA PI) and middle cerebral artery pulsatility indices (MCA PI), cerebroplacental ratio, absent end diastolic flow (AEDF), birthweight, prematurity, neonatal intensive care unit admission and adverse obstetric outcomes in women with small for gestational age pregnancies. It was hypothesised that maternal pregnancy-specific stress would be associated with fetoplacental haemodynamics and neonatal outcomes. Design: This is a secondary analysis of data collected for a large-scale prospective observational study. Setting: This study was conducted in the seven major obstetric hospitals in Ireland and Northern Ireland. Participants: Participants included 331 women who participated in the Prospective Observational Trial to Optimise Paediatric Health in Intrauterine Growth Restriction. Women with singleton pregnancies between 24 and 36 weeks gestation, estimated fetal weight <10th percentile and no major structural or chromosomal abnormalities were included. Primary and secondary outcome measures Serial Doppler ultrasound examinations of the umbilical and middle cerebral arteries between 20 and 42 weeks gestation, Pregnancy Distress Questionnaire (PDQ) scores between 23 and 40 weeks gestation and neonatal outcomes. Results: Concerns about physical symptoms and body image at 35â40 weeks were associated with lower odds of abnormal UAPI (OR 0.826, 95% CI 0.696 to 0.979, p=0.028). PDQ score (OR 1.073, 95% CI 1.012 to 1.137, p=0.017), concerns about birth and the baby (OR 1.143, 95% CI 1.037 to 1.260, p=0.007) and concerns about physical symptoms and body image (OR 1.283, 95% CI 1.070 to 1.538, p=0.007) at 29â34 weeks were associated with higher odds of abnormal MCA PI. Concerns about birth and the baby at 29â34 weeks (OR 1.202, 95% CI 1.018 to 1.421, p=0.030) were associated with higher odds of AEDF. Concerns about physical symptoms and body image at 35â40 weeks were associated with decreased odds of neonatal intensive care unit admission (OR 0.635, 95% CI 0.435 to 0.927, p=0.019). Conclusions: These findings suggest that fetoplacental haemodynamics may be a mechanistic link between maternal prenatal stress and fetal and neonatal well-being, but additional research is required
\u27Struggling with Language\u27 : Indigenous movements for Linguistic Security and the Politics of Local Community
In this article, I explore the relationship between linguistic diversity and political power. Specifically, I outline some of the ways that linguistic diversity has served as a barrier to the centralization of power, thus constraining, for example, the political practice of empire-formation. A brief historical example of this dynamic is presented in the case of Spanish colonialism of the 16th-century. The article proceeds then to demonstrate how linguistic diversity remains tied to struggles against forms of domination. I argue that in contemporary indigenous movements for linguistic security, the languages themselves are not merely conceived of as the object of the political struggle, but also as the means to preserve a space for local action and deliberation â a âpolitics of local communityâ. I show that linguistic diversity and the devolution of political power to the local level are in a mutually reinforcing relationship. Finally, I consider the implications of this thesis for liberal theorizing on language rights, arguing that such theory cannot fully come to terms with this political-strategic dimension of language struggles
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