The photometric properties of a vast stellar substructure in the outskirts of M33

We have surveyed $\sim40$sq.degrees surrounding M33 with CFHT MegaCam in the g and i filters, as part of the Pan-Andromeda Archaeological Survey. Our observations are deep enough to resolve the top 4mags of the red giant branch population in this galaxy. We have previously shown that the disk of M33 is surrounded by a large, irregular, low-surface brightness substructure. Here, we quantify the stellar populations and structure of this feature using the PAndAS data. We show that the stellar populations of this feature are consistent with an old population with $<[Fe/H]>\sim-1.6$dex and an interquartile range in metallicity of $\sim0.5$dex. We construct a surface brightness map of M33 that traces this feature to $\mu_V\simeq33$mags\,arcsec$^{-2}$. At these low surface brightness levels, the structure extends to projected radii of $\sim40$kpc from the center of M33 in both the north-west and south-east quadrants of the galaxy. Overall, the structure has an "S-shaped" appearance that broadly aligns with the orientation of the HI disk warp. We calculate a lower limit to the integrated luminosity of the structure of $-12.7\pm0.5$mags, comparable to a bright dwarf galaxy such as Fornax or AndII and slightly less than $1\$ of the total luminosity of M33. Further, we show that there is tentative evidence for a distortion in the distribution of young stars near the edge of the HI disk that occurs at similar azimuth to the warp in HI. The data also hint at a low-level, extended stellar component at larger radius that may be a M33 halo component. We revisit studies of M33 and its stellar populations in light of these new results, and we discuss possible formation scenarios for the vast stellar structure. Our favored model is that of the tidal disruption of M33 in its orbit around M31.Comment: Accepted for publication in ApJ. 17 figures. ApJ preprint forma

Algebraic varieties with automorphism groups of maximal rank

We confirm, to some extent, the belief that a projective variety X has the largest number (relative to the dimension of X) of independent commuting automorphisms of positive entropy only when X is birational to a complex torus or a quotient of a torus. We also include an addendum to an early paper though it is not used in the present paper.Comment: Mathematische Annalen (to appear

Magnetic-field dependence of the critical currents in a periodic coplanar array of narrow superconducting strip

We calculate the magnetic-field dependence of the critical current due to both geometrical edge barriers and bulk pinning in a periodic coplanar array of narrow superconducting strips. We find that in zero or low applied magnetic fields the critical current can be considerably enhanced by the edge barriers, but in modest applied magnetic fields the critical current reduces to that due to bulk pinning alone.Comment: 23 pages, 7 figure

Microwave Surface Impedance of YBCO:123 crystals: Experiment and comparison to a d-wave model

We present measurements of the microwave surface resistance Rs and the penetration depth lambda of YBCO:123 crystals. At low T obeys lambda(T) a polynomial behavior, while Rs displays a characteristic non-monotonic T-dependence. A detailed comparison of the experimental data is made to a model of d-wave superconductivity which includes both elastic and inelastic scattering. While the model reproduces the general features of the experimental data, three aspects of the parameters needed are worth noting. The elastic scattering rate required to fit the data is much smaller than measured from the normal state, the scattering phase shifts have to be close to pi/2 and a strong coupling value of the gap parameter 2\Delta(0)/kTc = 6 is needed. On the experimental side the uncertainties regarding the material parameters lambda(0) and Rs,res(0) further complicate a quantitative comparison. For one sample does Rs,res(0) agree with the intrinsic value which results from the d-wave model.Comment: uuencoded tar.Z, 11 pages with 5 figures, used style files: elsart and graphicx, PS-file available at http://sagar.cas.neu.edu/preprints.htm

High incidence and viral load of HHV-6A in a multi-centre kidney transplant cohort

Human herpesvirus 6 (HHV-6) is a common opportunistic pathogen in kidney transplant recipients. Two distinct species of HHV-6, HHV-6A and HHV-6B, have been identified, of which the latter seems to be dominant. However, it is unclear whether they increase the likelihood of other viral reactivations. We characterized a multi-centre cohort of 93 patients along nine study visits for viral load. We tested for the following viruses: HHV-6A and HHV-6B, the herpesviruses cytomegalovirus (CMV) and Epstein-Barr virus (EBV) and the polyomavirus BK (BKV). We detected HHV-6A viral load in 48 (51.6%) patients, while the incidence of HHV-6B was much lower, being detected in 6 (6.5%) patients. The incidence of HHV-6A was higher than of BKV, CMV and EBV. HHV-6A also demonstrated higher viral loads than the rest of viruses. There was a non-significant trend of association between HHV-6A and HHV-6B as co-infection, whereas no increased incidence of other viruses among patients with HHV-6A reactivation was observed. There was no negative effect of high HHV-6A (&gt;10,000 copies/ml) load on markers of renal graft and hepatic function or blood count twelve months post-transplant. In contrast to previously published data, our results show a clear dominance of HHV-6A in peripheral blood when compared to HHV-6B, with higher incidence and viral load levels. Despite the high HHV-6A loads observed, we did not identify any negative effects on posttransplant outcome

Latexin expression is downregulated in human gastric carcinomas and exhibits tumor suppressor potential

<p>Abstract</p> <p>Background</p> <p>Latexin, also known as endogenous carboxypeptidase inhibitor (CPI), has been found to inhibit mouse stem cell populations and lymphoma cell proliferation, demonstrating its potential role as a tumor suppressor. Our previous study also suggested a correlation between latexin expression and malignant transformation of immortalized human gastric epithelial cells. Here, we examined latexin expression in human gastric carcinomas and investigated the effect of differential latexin expression on proliferation of gastric cancer cells <it>in vitro </it>and <it>in vivo</it>.</p> <p>Methods</p> <p>Monoclonal antibody against human latexin was prepared and immunohistochemical analysis was performed to detect latexin expression in 41 paired gastric carcinomas and adjacent normal control tissues. Human gastric cancer cells MGC803 (latexin negative) stably transfected with LXN gene and BGC823 cells (latexin positive) stably transfected with antisense LXN gene were established for anchorage-dependent colony formation assay and tumorigenesis assay in nude mice. Differentially expressed genes in response to exogeneous latexin expression were screened using microarray analysis and identified by RT-PCR. Bisulfite sequencing was performed to analyze the correlation of the methylation status of LXN promoter with latexin expression in cell lines.</p> <p>Results</p> <p>Immunohistochemical analysis showed significantly reduced latexin expression in gastric carcinomas (6/41, 14.6%) compared to control tissues (31/41, 75.6%) (<it>P </it>< 0.05). Overexpression of LXN gene in MGC803 cells inhibited colony formation and tumor growth in nude mice. Conversely, BGC823 cells transfected with antisense LXN gene exhibited enhanced tumor growth and colony formation. Additionally, several tumor related genes, including Maspin, WFDC1, SLPI, S100P, and PDGFRB, were shown to be differentially expressed in MGC803 cells in response to latexin expression. Differential expression of Maspin and S100P was also identified in BGC823 cells while latexin expression was downregulated. Further bisulfite sequencing of the LXN gene promoter indicated CpG hypermethylation was correlated with silencing of latexin expression in human cells.</p> <p>Conclusions</p> <p>Latexin expression was reduced in human gastric cancers compared with their normal control tissues. The cellular and molecular evidences demonstrated the inhibitory effect of latexin in human gastric cancer cell growth and tumorigenicity. These results strongly suggest the possible involvement of latexin expression in tumor suppression.</p

Characteristics of Mothers Caring for Children During Episodes of Homelessness

This study provides a description of the physical, psychological, and substance use problems of adult homeless women who are and are not caring for children. We also examined differences in the characteristics of these two groups of women. Interviews were conducted with 148 homeless women from three mid-sized U.S. cities, 24.3% of whom were caring for at least one child. Our results showed that women caring for children were more likely to be sheltered and have health insurance. Homeless women caring for children and solitary homeless women were generally similar in terms of substance abuse problems. However, rates of Borderline Personality Disorder were higher among women caring for children than among solitary homeless women. Our results are somewhat consistent with previous research, with the exception of substance abuse problems and mental health problems, which were shown to be equally problematic for all women, regardless of current caregiving status