72 research outputs found
PRIMUS: The Effect of Physical Scale on the Luminosity-Dependence of Galaxy Clustering via Cross-Correlations
We report small-scale clustering measurements from the PRIMUS spectroscopic
redshift survey as a function of color and luminosity. We measure the
real-space cross-correlations between 62,106 primary galaxies with PRIMUS
redshifts and a tracer population of 545,000 photometric galaxies over
redshifts from z=0.2 to z=1. We separately fit a power-law model in redshift
and luminosity to each of three independent color-selected samples of galaxies.
We report clustering amplitudes at fiducial values of z=0.5 and L=1.5 L*. The
clustering of the red galaxies is ~3 times as strong as that of the blue
galaxies and ~1.5 as strong as that of the green galaxies. We also find that
the luminosity dependence of the clustering is strongly dependent on physical
scale, with greater luminosity dependence being found between r=0.0625 Mpc/h
and r=0.25 Mpc/h, compared to the r=0.5 Mpc/h to r=2 Mpc/h range. Moreover,
over a range of two orders of magnitude in luminosity, a single power-law fit
to the luminosity dependence is not sufficient to explain the increase in
clustering at both the bright and faint ends at the smaller scales. We argue
that luminosity-dependent clustering at small scales is a necessary component
of galaxy-halo occupation models for blue, star-forming galaxies as well as for
red, quenched galaxies.Comment: 13 pages, 6 figures, 5 tables; published in ApJ (revised to match
published version
Modeling Galactic Conformity with the Color-Halo Age Relation in the Illustris Simulation
Comparisons between observational surveys and galaxy formation models find
that the mass of dark matter haloes can largely explain galaxies' stellar mass.
However, it remains uncertain whether additional environmental variables,
generally referred to as assembly bias, are necessary to explain other galaxy
properties. We use the Illustris Simulation to investigate the role of assembly
bias in producing galactic conformity by considering 18,000 galaxies with
> . We find a significant signal of
galactic conformity: out to distances of about 10 Mpc, the mean red fraction of
galaxies around redder galaxies is higher than around bluer galaxies at fixed
stellar mass. Dark matter haloes exhibit an analogous conformity signal, in
which the fraction of haloes formed at earlier times (old haloes) is higher
around old haloes than around younger ones at fixed halo mass. A plausible
interpretation of galactic conformity can be given as a combination of the halo
conformity signal with the galaxy color-halo age relation: at fixed stellar
mass, particularly toward the low-mass end, Illustris' galaxy colors correlate
with halo age, with the reddest galaxies (often satellites) being
preferentially found in the oldest haloes. In fact, we can explain the galactic
conformity effect with a simple semi-empirical model, by assigning stellar mass
based on halo mass (abundance matching) and by assigning galaxy color based on
halo age (age matching). We investigate other interpretations for the galactic
conformity, particularly its dependence on the isolation criterion and on the
central-satellite information. Regarding comparison to observations, we
conclude that the adopted selection/isolation criteria, projection effects, and
stacking techniques can have a significant impact on the measured amplitude of
the conformity signal.Comment: 15 pages, 8 figures; accepted for publication in MNRAS (minor
revisions to match accepted version
Dark Matter Halo Models of Stellar Mass-Dependent Galaxy Clustering in PRIMUS+DEEP2 at 0.2<z<1.2
We utilize CDM halo occupation models of galaxy clustering to
investigate the evolving stellar mass dependent clustering of galaxies in the
PRIsm MUlti-object Survey (PRIMUS) and DEEP2 Redshift Survey over the past
eight billion years of cosmic time, between . These clustering
measurements provide new constraints on the connections between dark matter
halo properties and galaxy properties in the context of the evolving
large-scale structure of the universe. Using both an analytic model and a set
of mock galaxy catalogs, we find a strong correlation between central galaxy
stellar mass and dark matter halo mass over the range
-, approximately consistent
with previous observations and theoretical predictions. However, the
stellar-to-halo mass relation (SHMR) and the mass scale where star formation
efficiency reaches a maximum appear to evolve more strongly than predicted by
other models, including models based primarily on abundance-matching
constraints. We find that the fraction of satellite galaxies in haloes of a
given mass decreases significantly from to , partly due to
the fact that haloes at fixed mass are rarer at higher redshift and have lower
abundances. We also find that the ratio, a model parameter
that quantifies the critical mass above which haloes host at least one
satellite, decreases from at to at .
Considering the evolution of the subhalo mass function vis-\`{a}-vis satellite
abundances, this trend has implications for relations between satellite
galaxies and halo substructures and for intracluster mass, which we argue has
grown due to stripped and disrupted satellites between and
.Comment: 17 pages, 9 figures and 4 tables; Astrophysical Journal, publishe
Revisiting histories of anti-racist thought and activism
This piece reconsiders histories of anti-racist thought and practice, including the linkages between anti-racisms and other traditions of liberatory thought. We argue that anti-racism should be understood as a strand in radical thought linking internationalism, institutional critique and street activism, in the process interfeeding with other social movements. The traditions of anti-racist thought discussed in this special issue exemplify these cross-cutting influences
Developing a core outcome set for the health outcomes for children and adults with congenital oesophageal atresia and/or tracheo-oesophageal fistula: OCELOT task group study protocol
Introduction: Heterogeneity in reported outcomes of infants with oesophageal atresia (OA) with or without tracheo-oesophageal fistula (TOF) prevents effective data pooling. Core outcome sets (COS) have been developed for many conditions to standardise outcome reporting, facilitate meta-analysis and improve the relevance of research for patients and families. Our aim is to develop an internationally-agreed, comprehensive COS for OA-TOF, relevant from birth through to transition and adulthood. Methods and analysis: A long list of outcomes will be generated using (1) a systematic review of existing studies on OA-TOF and (2) qualitative research with children (patients), adults (patients) and families involving focus groups, semistructured interviews and self-reported outcome activity packs. A two-phase Delphi survey will then be completed by four key stakeholder groups: (1) patients (paediatric and adult); (2) families; (3) healthcare professionals; and (4) researchers. Phase I will include stakeholders individually rating the importance and relevance of each long-listed outcome using a 9-point Likert scale, with the option to suggest additional outcomes not already included. During phase II, stakeholders will review summarised results from phase I relative to their own initial score and then will be asked to rescore the outcome based on this information. Responses from phase II will be summarised using descriptive statistics and a predefined definition of consensus for inclusion or exclusion of outcomes. Following the Delphi process, stakeholder experts will be invited to review data at a consensus meeting and agree on a COS for OA-TOF. Ethics and dissemination: Ethical approval was sought through the Health Research Authority via the Integrated Research Application System, registration no. 297026. However, approval was deemed not to be required, so study sponsorship and oversight were provided by Alder Hey Children’s NHS Foundation Trust. The study has been prospectively registered with the COMET Initiative. The study will be published in an open access forum
Systemic treatment with pulsed electromagnetic fields do not affect bone microarchitecture in osteoporotic rats
Purpose: Pulsed electromagnetic fields (PEMF) are currently used in the treatment of spinal fusions and non-unions. There are indications that PEMF might also be effective in the treatment of osteoporosis. In this study we examined whether whole-body PEMF treatment affects the bone microarchitecture in an osteoporotic rat model. Methods: Twenty-week-old female rats were ovariectomised (n020). Four different PEMF treatment protocols based on previous experimental studies and based on clinically used PEMF signals were examined (2 h/day, 5 days/week). A control group did not receive PEMF. At zero, three and six weeks cancellous and cortical bone architectural changes at the proximal tibia were evaluated using in vivo microCT scanning. Results: PEMF treatment did not induce any changes in cancellous or cortical bone compared to untreated controls. Conclusions: Although previous studies have shown strong effects of PEMF in osteoporosis we were unable to demonstrate this in any of the treatment protocols. Using in vivo microCT scanning we were able to identify small bone changes in time. Subtle differences in the experimental setup might explain the differences in study outcomes in the literature. Since PEMF treatment is safe, future experimental studies on the effect of PEMF on bone can better be performed directly on humans, eliminating the potential translation issues between animals and humans. In this study we found no support for the use of PEMF in the treatment of osteoporosis
Full-length transcript sequencing of human and mouse cerebral cortex identifies widespread isoform diversity and alternative splicing.
Alternative splicing is a post-transcriptional regulatory mechanism producing distinct mRNA molecules from a single pre-mRNA with a prominent role in the development and function of the central nervous system. We used long-read isoform sequencing to generate full-length transcript sequences in the human and mouse cortex. We identify novel transcripts not present in existing genome annotations, including transcripts mapping to putative novel (unannotated) genes and fusion transcripts incorporating exons from multiple genes. Global patterns of transcript diversity are similar between human and mouse cortex, although certain genes are characterized by striking differences between species. We also identify developmental changes in alternative splicing, with differential transcript usage between human fetal and adult cortex. Our data confirm the importance of alternative splicing in the cortex, dramatically increasing transcriptional diversity and representing an important mechanism underpinning gene regulation in the brain. We provide transcript-level data for human and mouse cortex as a resource to the scientific community
Adult Type 3 Adenylyl Cyclase–Deficient Mice Are Obese
Background: A recent study of obesity in Swedish men found that polymorphisms in the type 3 adenylyl cyclase (AC3) are associated with obesity, suggesting the interesting possibility that AC3 may play a role in weight control. Therefore, we examined the weight of AC3 mice over an extended period of time. Methodology/Principal Findings: We discovered that AC3 2/2 mice become obese as they age. Adult male AC3 2/2 mice are about 40 % heavier than wild type male mice while female AC3 2/2 are 70 % heavier. The additional weight of AC3 2/2 mice is due to increased fat mass and larger adipocytes. Before the onset of obesity, young AC3 2/2 mice exhibit reduced physical activity, increased food consumption, and leptin insensitivity. Surprisingly, the obesity of AC3 2/2 mice is not due to a loss of AC3 from white adipose and a decrease in lipolysis. Conclusions/Significance: We conclude that mice lacking AC3 exhibit obesity that is apparently caused by low locomotor activity, hyperphagia, and leptin insensitivity. The presence of AC3 in primary cilia of neurons of the hypothalamus suggests that cAMP signals generated by AC3 in the hypothalamus may play a critical role in regulation of body weight
Monitoring activities of teenagers to comprehend their habits: study protocol for a mixed-methods cohort study
Abstract: Background: Efforts to increase physical activity in youth need to consider which activities are most likely to be sustained over time in order to promote lifelong participation in physical activity. The Monitoring Activities of Teenagers to Comprehend their Habits (MATCH) study is a prospective cohort study that uses quantitative and qualitative methods to develop new knowledge on the sustainability of specific physical activities. Methods/design: Eight hundred and forty-three grade 5 and 6 students recruited from 17 elementary schools in New Brunswick, Canada, are followed-up three times per year. At each survey cycle, participants complete self-report questionnaires in their classroom under the supervision of trained data collectors. A sub-sample of 24 physically active students is interviewed annually using a semi-structured interview protocol. Parents (or guardians) complete telephone administered questionnaires every two years, and a health and wellness school audit is completed for each school. Discussion: MATCH will provide a description of the patterns of participation in specific physical activities in youth, and enable identification of the determinants of maintenance, decline, and uptake of participation in each activity. These data will inform the development of interventions that take into account which activities are the most likely to be maintained and why activities are maintained or dropped
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