Implications of the X-ray Variability for the Mass of MCG-6-30-15

The bright Seyfert 1 galaxy \mcg shows large variability on a variety of time scales. We study the \aproxlt 3 day time scale variability using a set of simultaneous archival observations that were obtained from \rxte and the {\it Advanced Satellite for Cosmology and Astrophysics} (\asca). The \rxte\ observations span nearly $10^6$ sec and indicate that the X-ray Fourier Power Spectral Density has an rms variability of 16%, is flat from approximately 10^{-6} - 10^{-5} Hz, and then steepens into a power law $\propto f^{-\alpha}$ with \alpha\aproxgt 1. A further steepening to $\alpha \approx 2$ occurs between 10^{-4}-10^{-3} Hz. The shape and rms amplitude are comparable to what has been observed in \ngc and \cyg, albeit with break frequencies that differ by a factor of 10^{-2} and 10^{4}, respectively. If the break frequencies are indicative of the central black hole mass, then this mass may be as low as $10^6 {\rm M}_\odot$. An upper limit of $\sim 2$ ks for the relative lag between the 0.5-2 keV \asca band compared to the 8-15 keV \rxte band was also found. Again by analogy with \ngc and \cyg, this limit is consistent with a relatively low central black hole mass.Comment: 5 pages, 3 figures, LaTeX, uses emulateapj.sty and apjfonts.sty, revised version, accepted for publication in ApJ Letter

League tables and concentric banding: how similar are the employment and education domains of the Index of Multiple Deprivation 2010?

This paper seeks to provide further evidence about ‘league table’ orderings for deprivation in local areas, especially for two domains – employment and education – which seem likely to be closely related. Rather than relying solely on administrative Local Authority areas and functional economic areas, our focus is to refine the concentric banding approach introduced in Nolan et al. (Local Economy 27(4): 403–418, 2012), and to apply it throughout England. We also introduce two new procedures by which areas might be systematically split into smaller components. The spatial distributions of employment and education deprivation turn out to be quite different (and distinct from the spatial distribution of overall deprivation). Throughout, there is clear evidence that it matters what size of local area is considered

Learning Mixtures of Gaussians in High Dimensions

Efficiently learning mixture of Gaussians is a fundamental problem in statistics and learning theory. Given samples coming from a random one out of k Gaussian distributions in Rn, the learning problem asks to estimate the means and the covariance matrices of these Gaussians. This learning problem arises in many areas ranging from the natural sciences to the social sciences, and has also found many machine learning applications. Unfortunately, learning mixture of Gaussians is an information theoretically hard problem: in order to learn the parameters up to a reasonable accuracy, the number of samples required is exponential in the number of Gaussian components in the worst case. In this work, we show that provided we are in high enough dimensions, the class of Gaussian mixtures is learnable in its most general form under a smoothed analysis framework, where the parameters are randomly perturbed from an adversarial starting point. In particular, given samples from a mixture of Gaussians with randomly perturbed parameters, when n > {\Omega}(k^2), we give an algorithm that learns the parameters with polynomial running time and using polynomial number of samples. The central algorithmic ideas consist of new ways to decompose the moment tensor of the Gaussian mixture by exploiting its structural properties. The symmetries of this tensor are derived from the combinatorial structure of higher order moments of Gaussian distributions (sometimes referred to as Isserlis' theorem or Wick's theorem). We also develop new tools for bounding smallest singular values of structured random matrices, which could be useful in other smoothed analysis settings

A core function for p120-catenin in cadherin turnover

p120-catenin stabilizes epithelial cadherin (E-cadherin) in SW48 cells, but the mechanism has not been established. Here, we show that p120 acts at the cell surface to control cadherin turnover, thereby regulating cadherin levels. p120 knockdown by siRNA expression resulted in dose-dependent elimination of epithelial, placental, neuronal, and vascular endothelial cadherins, and complete loss of cell–cell adhesion. ARVCF and δ-catenin were functionally redundant, suggesting that proper cadherin-dependent adhesion requires the presence of at least one p120 family member. The data reveal a core function of p120 in cadherin complexes, and strongly predict a dose-dependent loss of E-cadherin in tumors that partially or completely down-regulate p120

Improved hatchery and grow-out technology for marine finfish aquaculture in the Asia–Pacific region

This project focussed on improving marine finfish aquaculture production in the Asia-Pacific region by focussing on key constraints: improving hatchery technology to improve the availability of seedstock; evaluating the nutritional needs of groupers to support the development of compounded pellet diets; and improving communication and coordination of marine finfish aquaculture research and development activities in the Asia-Pacific region

More than teacher directed or child initiated: Preschool curriculum type, parent involvement, and children's outcomes in the child-parent centers.

This study investigated the contributions of curriculum approach and parent involvement to the short- and long-term effects of preschool participation in the Title I Chicago Child-Parent Centers. Data came from the complete cohort of 989 low-income children (93% African American) in the Chicago Longitudinal Study, who attended preschool in the 20 Child-Parent Centers in 1983-1985 and kindergarten in 1985-1986. We found that implementation of an instructional approach rated high by Head Teachers in teacher-directed and child-initiated activities was most consistently associated with children’s outcomes, including school readiness at kindergarten entry, reading achievement in third and eighth grades, and avoidance of grade retention. Parent involvement in school activities, as rated by teachers and by parents, was independently associated with child outcomes from school readiness at kindergarten entry to eighth grade reading achievement and grade retention above and beyond the influence of curriculum approach. Findings indicate that instructional approaches that blend a teacher-directed focus with child-initiated activities and parental school involvement are origins of the long-term effects of participation in the Child-Parent Centers

The X-ray Remnant of SN1987A

We present high resolution Chandra observations of the remnant of SN1987A in the Large Magellanic Cloud. The high angular resolution of the Chandra X-ray Observatory (CXO) permits us to resolve the X-ray remnant. We find that the remnant is shell-like in morphology, with X-ray peaks associated with some of the optical hot spots seen in HST images. The X-ray light curve has departed from the linear flux increase observed by ROSAT, with a 0.5-2.0 keV luminosity of 1.5 x 10^35 erg/s in January 2000. We set an upper limit of 2.3 x 10^34 ergs/s on the luminosity of any embedded central source (0.5 - 2 keV). We also present a high resolution spectrum, showing that the X-ray emission is thermal in origin and is dominated by highly ionized species of O, Ne, Mg, and Si.Comment: 16 pages, 3 figures, Accepted for publication in ApJ Letter