A Dichotomy in Satellite Quenching Around L* Galaxies

We examine the star formation properties of bright (~0.1 L*) satellites around isolated ~L* hosts in the local Universe using spectroscopically confirmed systems in the Sloan Digital Sky Survey DR7. Our selection method is carefully designed with the aid of N-body simulations to avoid groups and clusters. We find that satellites are significantly more likely to be quenched than a stellar mass-matched sample of isolated galaxies. Remarkably, this quenching occurs only for satellites of hosts that are themselves quenched: while star formation is unaffected in the satellites of star-forming hosts, satellites around quiescent hosts are more than twice as likely to be quenched than stellar-mass matched field samples. One implication of this is that whatever shuts down star formation in isolated, passive L* galaxies also plays at least an indirect role in quenching star formation in their bright satellites. The previously-reported tendency for "galactic conformity" in color/morphology may be a by-product of this host-specific quenching dichotomy. The S\'ersic indices of quenched satellites are statistically identical to those of field galaxies with the same specific star formation rates, suggesting that environmental and secular quenching give rise to the same morphological structure. By studying the distribution of pairwise velocities between the hosts and satellites, we find dynamical evidence that passive host galaxies reside in dark matter halos that are ~45% more massive than those of star-forming host galaxies of the same stellar mass. We emphasize that even around passive hosts, the mere fact that galaxies become satellites does not typically result in star formation quenching: we find that only ~30% of ~0.1 L* galaxies that fall in from the field are quenched around passive hosts, compared with ~0% around star forming hosts.Comment: 14 pages, 9 figure

Morphology, growth characteristics and oestrogen-binding capacity of DMBA-induced mammary tumours from ovariectomized rats.

The morphology of 20 mammary adenocarcinomas induced by 7,12-dimethylbenz(a)anthracene (DMBA) in Sprague-Dawley rats was compared with their growth characteristics and oestrogen-binding capacity following ovariectomy. The capacity to bind (3H)oestradiol-17B did not appear to be related to the growth characteristics, time of appearance after DMBA administration, or time between ovariectomy and assay for specific oestrogen-binding proteins. Furthermore, different tumours appeared to have oestrogen-binding capacities unrelated to the percentage of neoplastic cells within the tumour, amount of inflammation, mast cell infiltration, or the presence of fluid-filled cysts. The only morphological features which appeared to be correlated with oestrogen-binding capacity were the number of mitoses and the lipid content of the tumour; that is, the oestrogen-binding capacity tended to be lower in tumours with moderate or large numbers of mitoses and in tumours with much lipid in the epithelial cells. Six of the 19 adenocarcinomas found prior to sacrifice either continued growing or remained static following ovariectomy, while the others underwent regression. In 5 of the regressing tumours a new growth phase was observed, usually beginning 2 months after ovariectomy. Tumours other thus osteosarcoma as well as fibroadenomas and Zymbal-gland tumours

Red Galaxy Growth and the Halo Occupation Distribution

We have traced the past 7 Gyr of red galaxy stellar mass growth within dark matter halos. We have determined the halo occupation distribution, which describes how galaxies reside within dark matter halos, using the observed luminosity function and clustering of 40,696 0.2<z<1.0 red galaxies in Bootes. Half of 10^{11.9} Msun/h halos host a red central galaxy, and this fraction increases with increasing halo mass. We do not observe any evolution of the relationship between red galaxy stellar mass and host halo mass, although we expect both galaxy stellar masses and halo masses to evolve over cosmic time. We find that the stellar mass contained within the red population has doubled since z=1, with the stellar mass within red satellite galaxies tripling over this redshift range. In cluster mass halos most of the stellar mass resides within satellite galaxies and the intra-cluster light, with a minority of the stellar mass residing within central galaxies. The stellar masses of the most luminous red central galaxies are proportional to halo mass to the power of a third. We thus conclude that halo mergers do not always lead to rapid growth of central galaxies. While very massive halos often double in mass over the past 7 Gyr, the stellar masses of their central galaxies typically grow by only 30%.Comment: Accepted for publication in the ApJ. 34 pages, 22 Figures, 5 Table

Gravitational detection of a low-mass dark satellite at cosmological distance

The mass-function of dwarf satellite galaxies that are observed around Local Group galaxies substantially differs from simulations based on cold dark matter: the simulations predict many more dwarf galaxies than are seen. The Local Group, however, may be anomalous in this regard. A massive dark satellite in an early-type lens galaxy at z = 0.222 was recently found using a new method based on gravitational lensing, suggesting that the mass fraction contained in substructure could be higher than is predicted from simulations. The lack of very low mass detections, however, prohibited any constraint on their mass function. Here we report the presence of a 1.9 +/- 0.1 x 10^8 M_sun dark satellite in the Einstein-ring system JVAS B1938+666 at z = 0.881, where M_sun denotes solar mass. This satellite galaxy has a mass similar to the Sagittarius galaxy, which is a satellite of the Milky Way. We determine the logarithmic slope of the mass function for substructure beyond the local Universe to be alpha = 1.1^+0.6_-0.4, with an average mass-fraction of f = 3.3^+3.6_-1.8 %, by combining data on both of these recently discovered galaxies. Our results are consistent with the predictions from cold dark matter simulations at the 95 per cent confidence level, and therefore agree with the view that galaxies formed hierarchically in a Universe composed of cold dark matter.Comment: 25 pages, 7 figures, accepted for publication in Nature (19 January 2012

Conjugation site heterogeneity causes variable electrostatic properties in Fc conjugates

Immunoconjugates, including antibody-drug conjugates and Fc-conjugates, represent a rapidly growing class of therapeutics undergoing clinical development. Despite their growing popularity, the high intrinsic heterogeneity of immunoconjugates often complicates the development process and limits their widespread application. In particular, immunoconjugate charge variants exhibit markedly different colloidal stabilities, solubilities, pharmacokinetics and tissue distributions. Charge variants arise spontaneously due to degradation and, depending on the type of drug, linker and conjugation site, through drug conjugation. Electrostatic changes in naked antibodies often result in poor performance characteristics, and therefore charge alterations due to degradation are critical to control. Charge properties are expected to be equally important to producing well-behaved ADCs. Charge-based methods of analysis, such as isoelectric focusing and ion exchange chromatography, are capable of probing the underlying complexities within immunoconjugate drug products. Despite the utility of these methods, there are only a few published reports of charge-based assays applied to immunoconjugates. In the present study, we sought to identify the effects of chemical conjugation on the electrostatic properties of Fc-conjugates. In order to minimize the effects of post-translational modifications (e.g. deamidation), a single Fc charge variant was isolated prior to conjugation of a fluorescent probe, Alexa Fluor 350, to the side chains of lysine residues. The resulting Fc-conjugates were assessed by a variety of analytical techniques, including isoelectric focusing and ion exchange chromatography, to determine their charge properties

Longitudinal Profiles of Girls' Irritable, Defiant and Antagonistic Oppositional Symptoms: Evidence for Group Based Differences in Symptom Severity

Three subdimensions of ODD symptoms have been proposed -angry/irritable (IR), argumentative/defiant (DF) and antagonism (AN). This study tested whether longitudinal symptom trajectories could be identified by these subdimensions. Group-based trajectory analysis was used to identify developmental trajectories of IR, DF and AN symptoms. Multi-group trajectory analysis was then used to identify how subdimension trajectories were linked together over time. Data were drawn from the Pittsburgh Girls Study (PGS; N = 2450), an urban community sample of girls between the ages of five--eight at baseline. We included five waves of annual data across ages five-13 to model trajectories. Three trajectories were identified for each ODD subdimension: DF and AN were characterized by high, medium and low severity groups; IR was characterized by low, medium stable, and high increasing groups. Multi-trajectory analysis confirmed these subdimensions were best linked together based on symptom severity. We did not identify girls' trajectory groups that were characterized predominantly by a particular subdimension of ODD symptoms. Membership in more severe symptom groups was significantly associated with worse outcomes five years later. In childhood and early adolescence girls with high levels of ODD symptoms can be identified, and these youth are characterized by a persistently elevated profile of IR, DF and AN symptoms. Further studies in clinical samples are required to examine the ICD-10 proposal that ODD with irritability is a distinct or more severe form of ODD

A fitting formula for the merger timescale of galaxies in hierarchical clustering

We study galaxy mergers using a high-resolution cosmological hydro/N-body simulation with star formation, and compare the measured merger timescales with theoretical predictions based on the Chandrasekhar formula. In contrast to Navarro et al., our numerical results indicate, that the commonly used equation for the merger timescale given by Lacey and Cole, systematically underestimates the merger timescales for minor mergers and overestimates those for major mergers. This behavior is partly explained by the poor performance of their expression for the Coulomb logarithm, \ln (m_pri/m_sat). The two alternative forms \ln (1+m_pri/m_sat) and 1/2\ln [1+(m_pri/m_sat)^2] for the Coulomb logarithm can account for the mass dependence of merger timescale successfully, but both of them underestimate the merger time scale by a factor 2. Since \ln (1+m_pri/m_sat) represents the mass dependence slightly better we adopt this expression for the Coulomb logarithm. Furthermore, we find that the dependence of the merger timescale on the circularity parameter \epsilon is much weaker than the widely adopted power-law \epsilon^{0.78}, whereas 0.94*{\epsilon}^{0.60}+0.60 provides a good match to the data. Based on these findings, we present an accurate and convenient fitting formula for the merger timescale of galaxies in cold dark matter models.Comment: 16 pages, 14 figures, accepted for publication in ApJ, minor changes in the last few sentences of the discussio

A Prospective Study of Periodontal Disease and Risk of Gastric and Duodenal Ulcer in Male Health Professionals

OBJECTIVES: Periodontal disease has been associated with higher circulating levels of inflammatory markers and conditions associated with chronic inflammation, including vascular disease, diabetes mellitus, and cancer. Limited data exist on the relationship between periodontal disease and gastric and duodenal ulcer. METHODS: We conducted a prospective cohort study of 49,120 men in the Health Professionals Follow-up Study, aged 40–75 years at enrollment in 1986. Biennially, we assessed periodontal disease, tooth loss, and other risk factors for gastric and duodenal ulcer. We validated diagnoses of gastric and duodenal ulcer through medical record review. We used Cox proportional hazards modeling, adjusting for potential confounders, to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: We documented 138 cases of gastric ulcer and 124 cases of duodenal ulcer with available information on Helicobacter pylori status over 24 years of follow-up. After adjustment for risk factors, including smoking and regular use of aspirin and non-steroidal anti-inflammatory drugs, men with periodontal disease with bone loss had a multivariate HR of ulcer of 1.62 (95% CI, 1.24–2.12). Periodontal disease appeared to be associated with a similar risk of developing ulcers that were H. pylori negative (HR 1.75; 95% CI, 1.26–2.43) than H. pylori positive (HR 1.40; 95% CI, 0.87-2.24), as well as ulcers in the stomach (HR 1.75; 95% CI, 1.21–2.53) than ulcers in the duodenum (HR 1.47; 95% CI, 0.98–2.19). CONCLUSIONS: Periodontal disease is associated with an increased risk of incident gastric and duodenal ulcer. This relationship may be mediated by alterations in the oral and gastrointestinal microbiome and/or systemic inflammatory factors