Asteroseismology of Eclipsing Binary Stars in the Kepler Era

Eclipsing binary stars have long served as benchmark systems to measure fundamental stellar properties. In the past few decades, asteroseismology - the study of stellar pulsations - has emerged as a new powerful tool to study the structure and evolution of stars across the HR diagram. Pulsating stars in eclipsing binary systems are particularly valuable since fundamental properties (such as radii and masses) can determined using two independent techniques. Furthermore, independently measured properties from binary orbits can be used to improve asteroseismic modeling for pulsating stars in which mode identifications are not straightforward. This contribution provides a review of asteroseismic detections in eclipsing binary stars, with a focus on space-based missions such as CoRoT and Kepler, and empirical tests of asteroseismic scaling relations for stochastic ("solar-like") oscillations.Comment: 28 pages, 12 figures, 2 tables; Proceedings of the AAS topical conference "Giants of Eclipse" (AASTCS-3), July 28 - August 2 2013, Monterey, C

Fitting the integrated Spectral Energy Distributions of Galaxies

Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc

Detectable clonal mosaicism and its relationship to aging and cancer

In an analysis of 31,717 cancer cases and 26,136 cancer-free controls from 13 genome-wide association studies, we observed large chromosomal abnormalities in a subset of clones in DNA obtained from blood or buccal samples. We observed mosaic abnormalities, either aneuploidy or copy-neutral loss of heterozygosity, of >2 Mb in size in autosomes of 517 individuals (0.89%), with abnormal cell proportions of between 7% and 95%. In cancer-free individuals, frequency increased with age, from 0.23% under 50 years to 1.91% between 75 and 79 years (P = 4.8 × 10(-8)). Mosaic abnormalities were more frequent in individuals with solid tumors (0.97% versus 0.74% in cancer-free individuals; odds ratio (OR) = 1.25; P = 0.016), with stronger association with cases who had DNA collected before diagnosis or treatment (OR = 1.45; P = 0.0005). Detectable mosaicism was also more common in individuals for whom DNA was collected at least 1 year before diagnosis with leukemia compared to cancer-free individuals (OR = 35.4; P = 3.8 × 10(-11)). These findings underscore the time-dependent nature of somatic events in the etiology of cancer and potentially other late-onset diseases

Distinct Alterations in the Guanylate Cyclase-C (GC-C)/Cyclic GMP (cGMP) Pathway Are Evident Across Different Subtypes of Irritable Bowel Syndrome (IBS) Patients

Background and Aims: Linaclotide, a GC-C agonist, reduces abdominal pain and improves constipation in patients with IBS with constipation (IBS-C).1 We have recently shown that linaclotide activates GC-C expressed on intestinal epithelial cells, resulting in the production and release of cGMP, which accelerates gastrointestinal transit and inhibits colonic nocicep- tors.1 We have shown that key components of the GC-C/cGMP signalling pathway are expressed within human colonic mucosa. However, it remains to be determined if compo- nents of this pathway are differentially expressed in different IBS patient subtypes. Methods: Recto-sigmoid mucosal biopsies were obtained from healthy subjects (N=10) and IBS patients (N=14), as per Rome II criteria. We compared IBS patients with mixed (constipation and diarrhea) bowel habits (IBS-M; N=7) and patients with IBS-C (N=7). RNA was extracted from biopsies and Taqman qRT-PCR used to assess mRNA expression of GC-C (GUCY2C); the endogenous GC-C agonists, guanylin (GUCA2A) and uroguanylin (GUCA2B); and the cGMP transporters MRP4 (ABCC4) and MRP5 (ABCC5). Expression of these targets was determined relative to the housekeeping genes 18sRNA and GAPDH. In separate biopsies, immunohistochemistry determined localization of GC-C/cGMP signalling pathway compo- nents to cellular structures. Results: In mucosal biopsies from healthy controls, guanylin was the most abundantly expressed component of the GC-C/cGMP signalling pathway, followed sequentially by uroguanylin (P<0.01), GC-C (P<0.001), MRP5 (P<0.001) and MRP4 (P<0.001), respectively. In IBS-M biopsies both of the endogenous GC-C agonists, guanylin and uroguanylin, were significantly reduced compared with healthy controls (P<0.05). By contrast, in IBS-C patient biopsies, MRP4 was significantly down-regulated compared with expression in biopsies from healthy controls (P<0.001). No significant change in either MRP5 or GC-C expression was observed between IBS patient subtypes and healthy controls. Immunohistochemistry revealed MRP4 expression on the apical side of colonic epithelial cells, whilst MRP5 displayed basolateral expression. Conclusions: Distinct alterations in the GC-C/cGMP pathway are evident between different subtypes of IBS patients and may contrib- ute to the pathophysiology of IBS. In IBS-M, reduced expression of the endogenous hormones guanylin and uroguanylin may contribute to alternating bowel habits. In IBS-C, a reduction in apically expressed MRP4 may result in reduced release of cGMP into the colonic lumen. Overall, these changes may help to explain some aspects of the pathophysiology associated with IBS and the differential stool frequency and symptom patterns between IBS subtypes, which are under further investigation.Andrea M. Harrington, Joel Castro, Richard L. Young, Caroline B. Kurtz, Inmaculada Silos-Santiago, Nam Q. Nguyen, Jane M. Andrews, Stuart M. Brierle