Galaxy Star Formation as a Function of Environment in the Early Data Release of the Sloan Digital Sky Survey

We present in this paper a detailed analysis of the effect of environment on the star formation activity of galaxies within the Early Data Release (EDR) of the Sloan Digital Sky Survey (SDSS). We have used the Halpha emission line to derive the star formation rate (SFR) for each galaxy within a volume-limited sample of 8598 galaxies with 0.05 less than or equal to z less than or equal to 0.095 and M (r*) less than or equal to 20.45. We find that the SFR of galaxies is strongly correlated with the local ( projected) galaxy density, and thus we present here a density-SFR relation that is analogous to the density-morphology relation. The effect of density on the SFR of galaxies is seen in three ways. First, the overall distribution of SFRs is shifted to lower values in dense environments compared with the field population. Second, the effect is most noticeable for the strongly star-forming galaxies (Halpha EW > 5 Angstrom) in the 75th percentile of the SFR distribution. Third, there is a break ( or characteristic density) in the density-SFR relation at a local galaxy density of similar to1 h(75)(-2) Mpc(-2). To understand this break further, we have studied the SFR of galaxies as a function of clustercentric radius from 17 clusters and groups objectively selected from the SDSS EDR data. The distribution of SFRs of cluster galaxies begins to change, compared with the field population, at a clustercentric radius of 3-4 virial radii (at the >1sigma statistical significance), which is consistent with the characteristic break in density that we observe in the density-SFR relation. This effect with clustercentric radius is again most noticeable for the most strongly star-forming galaxies. Our tests suggest that the density-morphology relation alone is unlikely to explain the density-SFR relation we observe. For example, we have used the ( inverse) concentration index of SDSS galaxies to classify late-type galaxies and show that the distribution of the star-forming (EW Halpha > 5Angstrom) late-type galaxies is different in dense regions ( within 2 virial radii) compared with similar galaxies in the field. However, at present, we are unable to make definitive statements about the independence of the density-morphology and density-SFR relation. We have tested our work against potential systematic uncertainties including stellar absorption, reddening, SDSS survey strategy, SDSS analysis pipelines, and aperture bias. Our observations are in qualitative agreement with recent simulations of hierarchical galaxy formation that predict a decrease in the SFR of galaxies within the virial radius. Our results are in agreement with recent 2dF Galaxy Redshift Survey results as well as consistent with previous observations of a decrease in the SFR of galaxies in the cores of distant clusters. Taken together, these works demonstrate that the decrease in SFR of galaxies in dense environments is a universal phenomenon over a wide range in density (from 0.08 to 10 h(75)(-2) Mpc(-2)) and redshift (out to z similar or equal to 0.5)

Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter

Naturally occurring diabetes mellitus (DM) is common in domestic cats (Felis catus). It has been proposed as a model for human Type 2 DM given many shared features. Small case studies demonstrate feline DM also occurs as a result of insulin resistance due to a somatotrophinoma. The current study estimates the prevalence of hypersomatotropism or acromegaly in the largest cohort of diabetic cats to date, evaluates clinical presentation and ease of recognition. Diabetic cats were screened for hypersomatotropism using serum total insulin-like growth factor-1 (IGF-1; radioimmunoassay), followed by further evaluation of a subset of cases with suggestive IGF-1 (>1000 ng/ml) through pituitary imaging and/ or histopathology. Clinicians indicated pre-test suspicion for hypersomatotropism. In total 1221 diabetic cats were screened; 319 (26.1%) demonstrated a serum IGF-1>1000 ng/ml (95% confidence interval: 23.6-28.6%). Of these cats a subset of 63 (20%) underwent pituitary imaging and 56/63 (89%) had a pituitary tumour on computed tomography; an additional three on magnetic resonance imaging and one on necropsy. These data suggest a positive predictive value of serum IGF-1 for hypersomatotropism of 95% (95% confidence interval: 90-100%), thus suggesting the overall hypersomatotropism prevalence among UK diabetic cats to be 24.8% (95% confidence interval: 21.2-28.6%). Only 24% of clinicians indicated a strong pre-test suspicion; most hypersomatotropism cats did not display typical phenotypical acromegaly signs. The current data suggest hypersomatotropism screening should be considered when studying diabetic cats and opportunities exist for comparative acromegaly research, especially in light of the many detected communalities with the human disease

Using multiple chronometers to establish a long, directly-dated lacustrine record:Constraining >600,000 years of environmental change at Chew Bahir, Ethiopia

Despite eastern Africa being a key location in the emergence of Homo sapiens and their subsequent dispersal out of Africa, there is a paucity of long, well-dated climate records in the region to contextualize this history. To address this issue, we dated a ∼293 m long composite sediment core from Chew Bahir, south Ethiopia, using three independent chronometers (radiocarbon, 40Ar/39Ar, and optically stimulated luminescence) combined with geochemical correlation to a known-age tephra. The site is located in a climatically sensitive region, and is close to Omo Kibish, the earliest documented Homo sapiens fossil site in eastern Africa, and to the proposed dispersal routes for H. sapiens out of Africa. The 30 ages generated by the various techniques are internally consistent, stratigraphically coherent, and span the full range of the core depth. A Bayesian age-depth model developed using these ages results in a chronology that forms one of the longest independently dated, high-resolution lacustrine sediment records from eastern Africa. The chronology illustrates that any record of environmental change preserved in the composite sediment core from Chew Bahir would span the entire timescale of modern human evolution and dispersal, encompassing the time period of the transition from Acheulean to Middle Stone Age (MSA), and subsequently to Later Stone Age (LSA) technology, making the core well-placed to address questions regarding environmental change and hominin evolutionary adaptation. The benefits to such studies of direct dating and the use of multiple independent chronometers are discussed. Highlights • Four independent dating methods applied to ∼293 m lake core from southern Ethiopia. • Reveals 620 ka high-resolution sedimentary record near key fossil hominin sites. • Mean accumulation rate of 0.47 mm/a comparable to other African lacustrine sediments. • Accumulation rate fell to 0.1 mm/a during MIS 2, likely due to reduced sediment supply. • Use of multiple independent chronometers is a powerful approach in lake settings

The C4 Clustering Algorithm: Clusters of Galaxies in the Sloan Digital Sky Survey

We present the "C4 Cluster Catalog", a new sample of 748 clusters of galaxies identified in the spectroscopic sample of the Second Data Release (DR2) of the Sloan Digital Sky Survey (SDSS). The C4 cluster--finding algorithm identifies clusters as overdensities in a seven-dimensional position and color space, thus minimizing projection effects which plagued previous optical clusters selection. The present C4 catalog covers ~2600 square degrees of sky with groups containing 10 members to massive clusters having over 200 cluster members with redshifts. We provide cluster properties like sky location, mean redshift, galaxy membership, summed r--band optical luminosity (L_r), velocity dispersion, and measures of substructure. We use new mock galaxy catalogs to investigate the sensitivity to the various algorithm parameters, as well as to quantify purity and completeness. These mock catalogs indicate that the C4 catalog is ~90% complete and 95% pure above M_200 = 1x10^14 solar masses and within 0.03 <=z <= 0.12. The C4 algorithm finds 98% of X-ray identified clusters and 90% of Abell clusters within 0.03 <= z <= 0.12. We show that the L_r of a cluster is a more robust estimator of the halo mass (M_200) than the line-of-sight velocity dispersion or the richness of the cluster. L_r. The final SDSS data will provide ~2500 C4 clusters and will represent one of the largest and most homogeneous samples of local clusters.Comment: 32 pages of figures and text accepted in AJ. Electronic version with additional tables, links, and figures is available at http://www.ctio.noao.edu/~chrism/c

Immunodeficiency, autoimmune thrombocytopenia and enterocolitis caused by autosomal recessive deficiency of PIK3CD-encoded phosphoinositide 3-kinase δ.

Phosphoinositide 3-kinase δ (PI3Kδ), a lipid kinase consisting of a catalytic (p110δ, encoded by PIK3CD) and a regulatory subunit (p85, encoded by PIK3R1), generates the second messenger phosphatidylinositol (3,4,5)-trisphosphate (PIP3) in the plasma membrane of leukocytes downstream of antigen and cytokine receptors.1 Signaling via PDK1, AKT, mTOR and downstream targets such as FOXO1, contributes to the metabolic and transcriptional changes required for the expansion, differentiation and effector function of lymphocytes. Activating germline mutations in PIK3CD cause the immune dysregulatory disease activated PI3Kδ syndrome (APDS), usually presenting with recurrent sinopulmonary infections in childhood, herpesvirus infections and CD4+ lymphopenia, underscoring the important role of balanced p110δ activity in human adaptive immunity. Ablation of p110δ in mice leads to aberrant T cell responses and intestinal inflammation. In humans, immune dysregulation including severe colitis is present in many cancer patients who are treated with the p110δ-specific inhibitor Idelalisib. Recently, one patient with autosomal recessive deficiency of p85α and two patients with loss-of function mutations in p110δ have been described who developed humoral immunodeficiency and colitis

Immune state is associated with natural dietary variation in wild mice Mus musculus domesticus

1. The ability, propensity and need to mount an immune response vary both among individuals and within a single individual over time.2. A wide array of parameters have been found to influence immune state in carefully controlled experiments, but we understand much less about which of these parameters are important in determining immune state in wild populations.3. Diet can influence immune responses, for example when nutrient availability is limited. We therefore predict that natural dietary variation will play a role in modulating immune state, but this has never been tested.4. We measured carbon and nitrogen stable isotope ratios in an island population of house mice Mus musculus domesticus as an indication of dietary variation, and the expression of a range of immune?related genes to represent immune state.5. After accounting for potential confounding influences such as age, sex and helminth load, we found a significant association between carbon isotope ratio and levels of immune activity in the mesenteric lymph nodes, particularly in relation to the inflammatory response.6. This association demonstrates the important interplay between diet and an animal's response to immune challenges, and therefore potentially its susceptibility to disease

Lactoferrin impact on gut microbiota in preterm infants with late-onset sepsis or necrotising enterocolitis: the MAGPIE mechanisms of action study

Background: Preterm infants have high rates of morbidity, especially from late-onset sepsis and necrotising enterocolitis. Lactoferrin is an anti-infective milk protein that may act through effects on gut bacteria, metabolites and epithelial cell function. The impact of supplemental lactoferrin in reducing late-onset sepsis was explored in the Enteral LactoFerrin In Neonates (ELFIN) trial. Objectives: The Mechanisms Affecting the Gut of Preterm Infants in Enteral feeding (MAGPIE) study was nested within the ELFIN trial and aimed to determine the impact of lactoferrin on gut microbiota and bacterial function, and changes preceding disease onset. We aimed to explore impacts on the stool bacteria and faecal/urinary metabolome using gas and liquid chromatography–mass spectrometry, and explore immunohistological pathways in resected tissue. Methods: Preterm infants from 12 NHS hospitals were enrolled in the study, and daily stool and urine samples were collected. Local sample collection data were combined with ELFIN trial data from the National Perinatal Epidemiology Unit, Oxford. The longitudinal impact of lactoferrin in healthy infants was determined, and samples that were collected before disease onset were matched with samples from healthy control infants. Established, quality-controlled 16S ribonucleic acid, gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry analyses were conducted. Validated databases and standardised workflows were used to identify bacteria and metabolites. Tissue samples from infants undergoing surgery and matched controls were analysed. Results: We recruited 479 preterm infants (mean gestation of 28.4 ± 2.3 weeks) and collected > 33,000 usable samples from 467 infants. 16S ribonucleic acid bacterial analysis was conducted on samples from 201 infants, of whom 20 had necrotising enterocolitis and 51 had late-onset sepsis, along with samples from healthy matched controls to explore longitudinal changes. The greatest change in relative bacterial abundance over time was observed in Staphylococcus, which decreased from 42 at aged 7–9 days to only 2 at aged 30–60 days (p < 0.001). Small but significant differences in community composition were observed between samples in each ELFIN trial group (R2 = 0.005; p = 0.04). Staphylococcus (p < 0.01), Haemophilus (p < 0.01) and Lactobacillus (p = 0.01) showed greater mean relative abundance in the placebo group than in the lactoferrin group. Gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry analyses showed that lactoferrin had limited impact on the metabolome. Liquid chromatography–mass spectrometry showed significant metabolite differences between necrotising enterocolitis or late-onset sepsis infants and healthy controls. The resected gut tissue analysis revealed 82 differentially expressed genes between healthy and necrotic tissue. Limitations: Although we recruited a large number of infants, collecting daily samples from every infant is challenging, especially in the few days immediately preceding disease onset. Conclusion: We conducted a large mechanistic study across multiple hospital sites and showed that, although lactoferrin significantly decreased the level of Staphylococcus and other key pathogens, the impact was smaller than those of other clinical variables. Immunohistochemistry identified multiple inflammatory pathways leading to necrotising enterocolitis and showed that the use of NHS pathology archive tissue is feasible in the context of a randomised controlled trial. Future work: We observed significant changes in the stool and urinary metabolome in cases preceding late-onset sepsis or necrotising enterocolitis, which provide metabolic targets for a future mechanistic and biomarker study. Trial registration: Current Controlled Trials ISRCTN12554594. Funding: This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership. This will be published in full in Efficacy and Mechanism Evaluation; Vol. 8, No. 14. See the NIHR Journals Library website for further project information

Mobility and kinship in the world’s first village societies

Around 10,000 y ago in southwest Asia, the cessation of a mobile lifestyle and the emergence of the first village communities during the Neolithic marked a fundamental change in human history. The first communities were small (tens to hundreds of individuals) but remained semisedentary. So-called megasites appeared soon after, occupied by thousands of more sedentary inhabitants. Accompanying this shift, the material culture and ancient ecological data indicate profound changes in economic and social behavior. A shift from residential to logistical mobility and increasing population size are clear and can be explained by either changes in fertility and/or aggregation of local groups. However, as sedentism increased, small early communities likely risked inbreeding without maintaining or establishing exogamous relationships typical of hunter-gatherers. Megasites, where large populations would have made endogamy sustainable, could have avoided this risk. To examine the role of kinship practices in the rise of megasites, we measured strontium and oxygen isotopes in tooth enamel from 99 individuals buried at Pınarbaşı, Boncuklu, and Çatalhöyük (Turkey) over 7,000 y. These sites are geographically proximate and, critically, span both early sedentary behaviors (Pınarbaşı and Boncuklu) and the rise of a local megasite (Çatalhöyük). Our data are consistent with the presence of only local individuals at Pınarbaşı and Boncuklu, whereas at Çatalhöyük, several nonlocals are present. The Çatalhöyük data stand in contrast to other megasites where bioarchaeological evidence has pointed to strict endogamy. These different kinship behaviors suggest that megasites may have arisen by employing unique, community-specific kinship practices

Mobility and kinship in the world's first village societies

Around 10,000 y ago in southwest Asia, the cessation of a mobile lifestyle and the emergence of the first village communities during the Neolithic marked a fundamental change in human history. The first communities were small (tens to hundreds of individuals) but remained semisedentary. So-called megasites appeared soon after, occupied by thousands of more sedentary inhabitants. Accompanying this shift, the material culture and ancient ecological data indicate profound changes in economic and social behavior. A shift from residential to logistical mobility and increasing population size are clear and can be explained by either changes in fertility and/or aggregation of local groups. However, as sedentism increased, small early communities likely risked inbreeding without maintaining or establishing exogamous relationships typical of hunter-gatherers. Megasites, where large populations would have made endogamy sustainable, could have avoided this risk. To examine the role of kinship practices in the rise of megasites, we measured strontium and oxygen isotopes in tooth enamel from 99 individuals buried at Pınarbaşı, Boncuklu, and Çatalhöyük (Turkey) over 7,000 y. These sites are geographically proximate and, critically, span both early sedentary behaviors (Pınarbaşı and Boncuklu) and the rise of a local megasite (Çatalhöyük). Our data are consistent with the presence of only local individuals at Pınarbaşı and Boncuklu, whereas at Çatalhöyük, several nonlocals are present. The Çatalhöyük data stand in contrast to other megasites where bioarchaeological evidence has pointed to strict endogamy. These different kinship behaviors suggest that megasites may have arisen by employing unique, community-specific kinship practices