A Hot DQ White Dwarf in the Open Star Cluster M35

We report the discovery of a hot DQ white dwarf, NGC 2168:LAWDS 28, that is a likely member of the 150-Myr old cluster NGC 2168 (Messier 35). The spectrum of the white dwarf is dominated by CII features. The effective temperature is difficult to estimate but likely > 20,000 K based on the temperatures of hot DQs with similar spectra. NGC2168:LAWDS 28 provides further evidence that hot DQs may be the ``missing'' high-mass helium-atmosphere white dwarfs. Based on published studies, we find that the DBA WD LP 475-242 is likely a member of the Hyades open cluster, as often assumed. These two white dwarfs are the entire sample of known He-atmosphere white dwarfs in open clusters with turnoff masses >2 solar masses. Based on the number of known cluster DA white dwarfs and a redetermination of the H-atmosphere:He-atmosphere ratio, commonly known as the DA:DB ratio, we re-examine the hypothesis that the H- to He-atmosphere ratio in open clusters is the same as the ratio in the field. Under this hypothesis, we calculate that five He-atmosphere WDs are expected to have been discovered, with a probability of finding fewer than three He-atmosphere white dwarfs of 0.08, or at the ~ 2-sigma level.Comment: 9 pages with 2 figures, uses LaTeX/AASTeX 5.2. Accepted for publications in ApJ Letter

An Initial Survey of White Dwarfs in the Sloan Digital Sky Survey

An initial assessment is made of white dwarf and hot subdwarf stars observed in the Sloan Digital Sky Survey. In a small area of sky (190 square degrees), observed much like the full survey will be, 269 white dwarfs and 56 hot subdwarfs are identified spectroscopically where only 44 white dwarfs and 5 hot subdwarfs were known previously. Most are ordinary DA (hydrogen atmosphere) and DB (helium) types. In addition, in the full survey to date, a number of WDs have been found with uncommon spectral types. Among these are blue DQ stars displaying lines of atomic carbon; red DQ stars showing molecular bands of C_2 with a wide variety of strengths; DZ stars where Ca and occasionally Mg, Na, and/or Fe lines are detected; and magnetic WDs with a wide range of magnetic field strengths in DA, DB, DQ, and (probably) DZ spectral types. Photometry alone allows identification of stars hotter than 12000 K, and the density of these stars for 15<g<20 is found to be ~2.2 deg^{-2} at Galactic latitudes 29-62 deg. Spectra are obtained for roughly half of these hot stars. The spectra show that, for 15<g<17, 40% of hot stars are WDs and the fraction of WDs rises to ~90% at g=20. The remainder are hot sdB and sdO stars.Comment: Accepted for AJ; 43 pages, including 12 figures and 5 table

Hepatic abscess in a pre-existed simple hepatic cyst as a late complication of sigmoid colon ruptured diverticula: a case report

<p>Abstract</p> <p>Introduction</p> <p>Hepatic abscesses have been reported as a rare complication of diverticulitis of the bowel. This complication is recognized more commonly at the time of the diagnosis of diverticulitis, or ruptured diverticula, but also can be diagnosed prior to surgery, or postoperatively.</p> <p>Case presentation</p> <p>This report describes a man who developed an hepatic abscess within a simple hepatic cyst, two months after operation for ruptured diverticula of the sigmoid colon. The abscess was drained surgically and the patient made a complete recovery.</p> <p>Conclusion</p> <p>The development of an hepatic abscess in a pre-existing hepatic cyst, secondary to diverticulitis, is a rare complication. A high degree of clinical suspicion is required for immediate diagnosis and treatment.</p

Unrelated Helpers in a Primitively Eusocial Wasp: Is Helping Tailored Towards Direct Fitness?

The paper wasp Polistes dominulus is unique among the social insects in that nearly one-third of co-foundresses are completely unrelated to the dominant individual whose offspring they help to rear and yet reproductive skew is high. These unrelated subordinates stand to gain direct fitness through nest inheritance, raising the question of whether their behaviour is adaptively tailored towards maximizing inheritance prospects. Unusually, in this species, a wealth of theory and empirical data allows us to predict how unrelated subordinates should behave. Based on these predictions, here we compare helping in subordinates that are unrelated or related to the dominant wasp across an extensive range of field-based behavioural contexts. We find no differences in foraging effort, defense behaviour, aggression or inheritance rank between unrelated helpers and their related counterparts. Our study provides no evidence, across a number of behavioural scenarios, that the behaviour of unrelated subordinates is adaptively modified to promote direct fitness interests

The Hot Stars of Old Open Clusters: M67, NGC 188 and NGC6791

We analyze ultraviolet (~1500 A) images of the old open clusters M67, NGC 188, and NGC 6791 obtained with Ultraviolet Imaging Telescope (UIT) during the second flight of the Astro observatory in March 1995. Twenty stars are detected on the UIT image of M67, including 11 blue stragglers, seven white dwarf candidates, and the yellow giant -- white dwarf binary S1040. The ultraviolet photometry of the blue stragglers F90 (S975) and F131 (S1082) suggests that these stars have hot subluminous companions. We present a semi-empirical integrated ultraviolet spectrum of M67, and show that the blue stragglers dominate the integrated spectrum at wavelengths shorter than 2600 A. The number of white dwarfs in M67 is roughly consistent with the number expected from white dwarf cooling models. Eight candidate sdB/sdO stars are detected in NGC 6791, and two are detected in NGC 188. The luminosity range 1.10 < log L/Lsun < 1.27, derived from the ultraviolet photometry of the six sdB candidates, is consistent with theoretical models of metal-rich hot horizontal branch (HB) stars. The fraction of hot HB stars in both NGC 6791 and NGC 188 is about 30%, implying that the integrated spectra of both clusters should show a UV turnup at least as strong as that observed in any elliptical galaxy.Comment: 34 pages incl. 6 postscript figures, accepted for publication in A

A New Very Cool White Dwarf Discovered by the Sloan Digital Sky Survey

Early data taken during commissioning of the SDSS have resulted in the discovery of a very cool white dwarf. It appears to have stronger collision induced absorption from molecular hydrogen than any other known white dwarf, suggesting it has a cooler temperature than any other. While its distance is presently unknown, it has a surprisingly small proper motion, making it unlikely to be a halo star. An analysis of white dwarf cooling times suggests that this object may be a low-mass star with a helium core. The SDSS imaging and spectroscopy also recovered LHS 3250, the coolest previously known white dwarf, indicating that the SDSS will be an effective tool for identifying these extreme objects.Comment: 15 pages, including 5 figures. Accepted for Astrophysical Journal Letter

DNA methylation defines regional identity of human intestinal epithelial organoids and undergoes dynamic changes during development.

OBJECTIVE: Human intestinal epithelial organoids (IEOs) are increasingly being recognised as a highly promising translational research tool. However, our understanding of their epigenetic molecular characteristics and behaviour in culture remains limited. DESIGN: We performed genome-wide DNA methylation and transcriptomic profiling of human IEOs derived from paediatric/adult and fetal small and large bowel as well as matching purified human gut epithelium. Furthermore, organoids were subjected to in vitro differentiation and genome editing using CRISPR/Cas9 technology. RESULTS: We discovered stable epigenetic signatures which define regional differences in gut epithelial function, including induction of segment-specific genes during cellular differentiation. Established DNA methylation profiles were independent of cellular environment since organoids retained their regional DNA methylation over prolonged culture periods. In contrast to paediatric and adult organoids, fetal gut-derived organoids showed distinct dynamic changes of DNA methylation and gene expression in culture, indicative of an in vitro maturation. By applying CRISPR/Cas9 genome editing to fetal organoids, we demonstrate that this process is partly regulated by TET1, an enzyme involved in the DNA demethylation process. Lastly, generating IEOs from a child diagnosed with gastric heterotopia revealed persistent and distinct disease-associated DNA methylation differences, highlighting the use of organoids as disease-specific research models. CONCLUSIONS: Our study demonstrates striking similarities of epigenetic signatures in mucosa-derived IEOs with matching primary epithelium. Moreover, these results suggest that intestinal stem cell-intrinsic DNA methylation patterns establish and maintain regional gut specification and are involved in early epithelial development and disease.This work was supported by funding from the following charitable organizations: Crohn’s in Childhood Research Association (CICRA), the Evelyn Trust, Crohn’s and Colitis in Childhood (“3Cs”), Addenbrooke’s Charitable Trust (ACT), and the Newlife Foundation for Disabled Children. J.K. was funded by a CICRA PhD studentship, K.H. was funded by an EBPOD EMBL-EBI/Cambridge Computational Biomedical Postdoctoral Fellowship. B-K.K. was supported by a Sir Henry Dale Fellowship from the Wellcome Trust and the Royal Society [101241/Z/13/Z] and received core support from the Wellcome Trust and MRC to the WT - MRC Cambridge Stem Cell Institute. GD and JF received support from the Wellcome Trust. J.F. was supported by a studentship from the MRC. P.R was supported by the Deutsche Forschungsgemeinschaft EXC306 Cluster “Inflammation at Interfaces” and BMBF IHEC DEEP TP5.2

Optical imaging and spectroscopy for the study of the human brain: status report.

This report is the second part of a comprehensive two-part series aimed at reviewing an extensive and diverse toolkit of novel methods to explore brain health and function. While the first report focused on neurophotonic tools mostly applicable to animal studies, here, we highlight optical spectroscopy and imaging methods relevant to noninvasive human brain studies. We outline current state-of-the-art technologies and software advances, explore the most recent impact of these technologies on neuroscience and clinical applications, identify the areas where innovation is needed, and provide an outlook for the future directions

Developmental pschology

xv, 572 p.; 22 cm

Science and behavior : an introduction to methods of psychological reearch.

Previous edition: 1986.Includes bibliographical references (pages 269-173) and index