Clues to the Origin of the Mass-Metallicity Relation: Dependence on Star Formation Rate and Galaxy Size

We use a sample of 43,690 galaxies selected from the Sloan Digital Sky Survey Data Release 4 to study the systematic effects of specific star formation rate (SSFR) and galaxy size (as measured by the half light radius, r_h) on the mass-metallicity relation. We find that galaxies with high SSFR or large r_h for their stellar mass have systematically lower gas phase-metallicities (by up to 0.2 dex) than galaxies with low SSFR or small r_h. We discuss possible origins for these dependencies, including galactic winds/outflows, abundance gradients, environment and star formation rate efficiencies.Comment: Accepted by ApJ Letter

A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed

The question of whether galaxy mergers are linked to the triggering of active galactic nuclei (AGN) continues to be a topic of considerable debate. The issue can be broken down into two distinct questions: 1) Can galaxy mergers trigger AGN? 2) Are galaxy mergers the dominant AGN triggering mechanism? A complete picture of the AGN-merger connection requires that both of these questions are addressed with the same dataset. In previous work, we have shown that galaxy mergers selected from the Sloan Digital Sky Survey (SDSS) show an excess of both optically-selected, and mid-IR colour-selected AGN, demonstrating that the answer to the first of the above questions is affirmative. Here, we use the same optical and mid-IR AGN selection to address the second question, by quantifying the frequency of morphological disturbances in low surface brightness r-band images from the Canada France Imaging Survey (CFIS). Only ~30 per cent of optical AGN host galaxies are morphologically disturbed, indicating that recent interactions are not the dominant trigger. However, almost 60 per cent of mid-IR AGN hosts show signs of visual disturbance, indicating that interactions play a more significant role in nuclear feeding. Both mid-IR and optically selected AGN have interacting fractions that are a factor of two greater than a mass and redshift matched non-AGN control sample, an excess that increases with both AGN luminosity and host galaxy stellar mass.Comment: Accepted for publication in MNRA

Dual and opposing roles of primary cilia in medulloblastoma development.

Recent work has shown that primary cilia are essential for Hedgehog (Hh) signaling during mammalian development. It is also known that aberrant Hh signaling can lead to cancer, but the role of primary cilia in oncogenesis is not known. Cerebellar granule neuron precursors (GNPs) can give rise to medulloblastomas, the most common malignant brain tumor in children. The primary cilium and Hh signaling are required for GNP proliferation. We asked whether primary cilia in GNPs have a role in medulloblastoma growth in mice. Genetic ablation of primary cilia blocked medulloblastoma formation when this tumor was driven by a constitutively active Smoothened protein (Smo), an upstream activator of Hh signaling. In contrast, removal of cilia was required for medulloblastoma growth by a constitutively active glioma-associated oncogene family zinc finger-2 (GLI2), a downstream transcription factor. Thus, primary cilia are either required for or inhibit medulloblastoma formation, depending on the initiating oncogenic event. Remarkably, the presence or absence of cilia was associated with specific variants of human medulloblastomas; primary cilia were found in medulloblastomas with activation in HH or WNT signaling but not in most medulloblastomas in other distinct molecular subgroups. Primary cilia could serve as a diagnostic tool and provide new insights into the mechanism of tumorigenesis

Prognostic value and functional consequences of cell cycle inhibitor p27Kip1 loss in medulloblastoma

BACKGROUND: The cyclin-dependent kinase inhibitor p27(Kip1) functions during normal cerebellar development and has demonstrated tumor suppressor functions in mouse models of medulloblastoma. Because P27 loss is associated with increased proliferation, we assessed whether P27 absence in surgical medulloblastoma specimens correlated with response to therapy in pediatric patients enrolled in two large studies. Additionally, we examined the functional consequence of p27(Kip1) loss in the SmoA1 medulloblastoma model to distinguish whether p27(Kip1) reduces tumor initiation or slows tumor progression. FINDINGS: Analysis of 87 well-characterized patient samples identified a threshold of P27 staining at which significant P27 loss correlated with poor patient outcome. The same criteria, applied to a second test set of tissues from 141 patients showed no difference in survival between patients with minimal P27 staining and others, suggesting that P27 levels alone are not a sufficient prognostic indicator for identifying standard-risk patients that may fail standard therapy. These findings were in contrast to prior experiments completed using a mouse medulloblastoma model. Analysis of cerebellar tumor incidence in compound mutant mice carrying the activated Smoothened (SmoA1) allele that were heterozygous or nullizygous for p27(Kip1) revealed that p27(Kip1) loss did not alter the frequency of tumor initiation. Tumors haploinsufficient or nullizygous for p27(Kip1) were, however, more invasive and displayed a higher proliferative index, suggesting p27(Kip1) loss may contribute to SmoA1 medulloblastoma progression. CONCLUSIONS: These studies revealed P27 loss affects medulloblastoma progression rather than initiation and that this putative biomarker should not be used for stratifying children with medulloblastoma to risk-based therapeutic regimens

Maximum likelihood estimation of reviewers' acumen in central review setting: categorical data

Successfully evaluating pathologists' acumen could be very useful in improving the concordance of their calls on histopathologic variables. We are proposing a new method to estimate the reviewers' acumen based on their histopathologic calls. The previously proposed method includes redundant parameters that are not identifiable and results are incorrect. The new method is more parsimonious and through extensive simulation studies, we show that the new method relies less on the initial values and converges to the true parameters. The result of the anesthetist data set by the new method is more convincing

An Arabic Version of the Spiritual Well-Being Scale

This article reports on two studies to develop and validate an Arabic language version of the Spiritual Well-Being Scale (SWBS). The first study was a pilot study at a major government university in Jordan (N = 75, students). The second and main study was conducted in 5 large regional hospitals in Jordan (N = 63, patients). The SWBS was translated from English to Arabic and reviewed by an expert panel for language, cultural, and spiritual consistency. The Arabic version of the SWBS was revised after the results of the pilot study and further reviewed by an expert panel. The resulting data were subjected to descriptive and factor analysis. Results showed that the final version of the SWBS used in the main study had a two-factor structure consistent with previous studies. Descriptive data for a range of demographic variables are presented. Issues of inadequate translation and lack of variation in responses for some items are identified and the results discussed in light of dominant Islamic theological frameworks. © 2012 Taylor and Francis Group, LLC

Galaxy Pairs in the Sloan Digital Sky Survey - III: Evidence of Induced Star Formation from Optical Colours

We have assembled a large, high quality catalogue of galaxy colours from the Sloan Digital Sky Survey Data Release 7, and have identified 21,347 galaxies in pairs spanning a range of projected separations (r_p < 80 h_{70}^{-1} kpc), relative velocities (\Delta v < 10,000 km/s, which includes projected pairs that are essential for quality control), and stellar mass ratios (from 1:10 to 10:1). We find that the red fraction of galaxies in pairs is higher than that of a control sample matched in stellar mass and redshift, and demonstrate that this difference is likely due to the fact that galaxy pairs reside in higher density environments than non-paired galaxies. We detect clear signs of interaction-induced star formation within the blue galaxies in pairs, as evidenced by a higher fraction of extremely blue galaxies, along with blueward offsets between the colours of paired versus control galaxies. These signs are strongest in close pairs (r_p < 30 h_{70}^{-1} kpc and \Delta v < 200 km/s), diminish for more widely separated pairs (r_p > 60 h_{70}^{-1} kpc and \Delta v < 200 km/s) and disappear for close projected pairs (r_p < 30 h_{70}^{-1} kpc and \Delta v > 3000 km/s). These effects are also stronger in central (fibre) colours than in global colours, and are found primarily in low- to medium-density environments. Conversely, no such trends are seen in red galaxies, apart from a small reddening at small separations which may result from residual errors with photometry in crowded fields. When interpreted in conjunction with a simple model of induced starbursts, these results are consistent with a scenario in which close peri-centre passages trigger induced star formation in the centres of galaxies which are sufficiently gas rich, after which time the galaxies gradually redden as they separate and their starbursts age.Comment: 17 pages. Accepted for publication in MNRA

Quantifying the impact of an extreme climate event on species diversity in fragmented temperate forests: the effect of the October 1987 storm on British broadleaved woodlands

1. We report the impact of an extreme weather event, the October 1987 severe storm, on fragmented woodlands in southern Britain. We analysed ecological changes between 1971 and 2002 in 143 200-m2 plots in 10 woodland sites exposed to the storm with an ecologically equivalent sample of 150 plots in 16 non-exposed sites. In both years, understorey species-richness, species composition, soil pH and woody basal area of the tree and shrub canopy were measured. 2. We tested the hypothesis that the storm had deflected sites from the wider national trajectory of an increase in woody basal area and reduced understorey species-richness associated with ageing canopies and declining woodland management. We also expected storm disturbance to amplify the background trend of increasing soil pH, a UK-wide response to reduced atmospheric sulphur deposition. Path analysis was used to quantify indirect effects of storm exposure on understorey species richness via changes in woody basal area and soil pH. 3. By 2002, storm exposure was estimated to have increased mean species richness per 200 m2 by 32%. Woody basal area changes were highly variable and did not significantly differ with storm exposure. 4. Increasing soil pH was associated with a 7% increase in richness. There was no evidence that soil pH increased more as a function of storm exposure. Changes in species richness and basal area were negatively correlated: a 3.4% decrease in richness occurred for every 0.1-m2 increase in woody basal area per plot. 5. Despite all sites substantially exceeding the empirical critical load for nitrogen deposition, there was no evidence that in the 15 years since the storm, disturbance had triggered a eutrophication effect associated with dominance of gaps by nitrophilous species. 6. Synthesis: Although the impacts of the 1987 storm were spatially variable in terms of impacts on woody basal area, the storm had a positive effect on understorey species richness. There was no evidence that disturbance had increased dominance of gaps by invasive species. This could change if recovery from acidification results in a soil pH regime associated with greater macronutrient availability

Quantifying the impact of an extreme climate event on species diversity in fragmented temperate forests: the effect of the October 1987 storm on British broadleaved woodlands

We report the impact of an extreme weather event, the October 1987 severe storm, on fragmented woodlands in southern Britain. We analysed ecological changes between 1971 and 2002 in 143 200-m2 plots in 10 woodland sites exposed to the storm with an ecologically equivalent sample of 150 plots in 16 non-exposed sites. Comparing both years, understorey plant species-richness, species composition, soil pH and woody basal area of the tree and shrub canopy were measured. We tested the hypothesis that the storm had deflected sites from the wider national trajectory of an increase in woody basal area and reduced understorey species-richness associated with ageing canopies and declining woodland management. We also expected storm disturbance to amplify the background trend of increasing soil pH, a UK-wide response to reduced atmospheric sulphur deposition. Path analysis was used to quantify indirect effects of storm exposure on understorey species richness via changes in woody basal area and soil pH. By 2002, storm exposure was estimated to have increased mean species richness per 200 m2 by 32%. Woody basal area changes were highly variable and did not significantly differ with storm exposure. Increasing soil pH was associated with a 7% increase in richness. There was no evidence that soil pH increased more as a function of storm exposure. Changes in species richness and basal area were negatively correlated: a 3.4% decrease in richness occurred for every 0.1-m2 increase in woody basal area per plot. Despite all sites substantially exceeding the empirical critical load for nitrogen deposition, there was no evidence that in the 15 years since the storm, disturbance had triggered a eutrophication effect associated with dominance of gaps by nitrophilous species. Synthesis. Although the impacts of the 1987 storm were spatially variable in terms of impacts on woody basal area, the storm had a positive effect on understorey species richness. There was no evidence that disturbance had increased dominance of gaps by invasive species. This could change if recovery from acidification results in a soil pH regime associated with greater macronutrient availability."Organismic and Evolutionary Biolog

Religious Identity, Religious Attendance, and Parental Control

Using a national sample of adolescents aged 10–18 years and their parents (N = 5,117), this article examines whether parental religious identity and religious participation are associated with the ways in which parents control their children. We hypothesize that both religious orthodoxy and weekly religious attendance are related to heightened levels of three elements of parental control: monitoring activities, normative regulations, and network closure. Results indicate that an orthodox religious identity for Catholic and Protestant parents and higher levels of religious attendance for parents as a whole are associated with increases in monitoring activities and normative regulations of American adolescents