A New Algorithm For Difference Image Analysis

In the context of difference image analysis (DIA), we present a new method for determining the convolution kernel matching a pair of images of the same field. Unlike the standard DIA technique which involves modelling the kernel as a linear combination of basis functions, we consider the kernel as a discrete pixel array and solve for the kernel pixel values directly using linear least-squares. The removal of basis functions from the kernel model is advantageous for a number of compelling reasons. Firstly, it removes the need for the user to specify such functions, which makes for a much simpler user application and avoids the risk of an inappropriate choice. Secondly, basis functions are constructed around the origin of the kernel coordinate system, which requires that the two images are perfectly aligned for an optimal result. The pixel kernel model is sufficiently flexible to correct for image misalignments, and in the case of a simple translation between images, image resampling becomes unnecessary. Our new algorithm can be extended to spatially varying kernels by solving for individual pixel kernels in a grid of image sub-regions and interpolating the solutions to obtain the kernel at any one pixel.Comment: MNRAS Letters Accepte

Disc galaxies with multiple triaxial structures. II. JHK surface photometry and numerical simulations

We present detailed JHK surface photometry with ellipse fits of 13 galaxies selected from previous optical observations as likely candidates for having a secondary bar or a triaxial bulge within the primary bar. We have found 7 double-barred galaxies, 3 double-barred galaxies with an additional intermediate structure with twisted isophotes, and 3 galaxies with a bar and central twisted isophotes. A global analysis of the structural parameter characteristics in the I- and K-bands is presented. Various numerical models of galaxies with bars within bars are also analysed using the ellipse fitting technique and compared to the observations. A thorough review of the possible hypotheses able to explain this phenomenon is given with emphasis on the most likely ones.Comment: 12 pages, AATEX. Accepted for publication in A&A. Large color postscript figures omitted (Figs. 1), figures 2-9 included; gzip'ed postscript files of the paper and Figs. 1 available via anonymous ftp at ftp://obsftp.unige.ch/pub/fri/aasjhk/ , files fri_aasjhk.ps.gz and ngc*.ps.g

SuperLupus: A Deep, Long Duration Transit Survey

SuperLupus is a deep transit survey monitoring a Galactic Plane field in the Southern hemisphere. The project is building on the successful Lupus Survey, and will double the number of images of the field from 1700 to 3400, making it one of the longest duration deep transit surveys. The immediate motivation for this expansion is to search for longer period transiting planets (5-8 days) and smaller radii planets. It will also provide near complete recovery for the shorter period planets (1-3 days). In March, April, and May 2008 we obtained the new images and work is currently in progress reducing these new data.Comment: 3 pages, 2 figures, to appear in the Proceedings of IAU Symposium 253, 2008: Transiting Planet

EDUCATORS’ PERSPECTIVES AND INSTRUCTION: FACTORS THAT INFLUENCE STUDENTS’ SELF-DETERMINATION SKILLS

This study was designed to understand the factors that influence educators’ perspectives and amount of instruction of student self-determination skills. A mixed methods correlational survey design was utilized to study these factors. The primary research question was “To what degree and in what manner do primary assignment, years of experience, and educators’ ratings of importance of each component of self-determination predict educators’ total mean self-reported amount of instruction of the components of self-determination?” Quantitative analyses revealed three significant results. For Research Question One, a stepwise multiple regression for predictor variables of ratings of importance found three variables that predicted the total mean self-reported amount of instruction: (a) rating of importance of goal-setting and attainment, (b) rating of importance of choice-making, and (c) rating of importance of self-awareness and self- knowledge. The total variance explained by the model was 21.4%. For Research Question Two, correlation coefficients were conducted to test the relationship between ratings of importance, self-reported amounts of instruction and the sum of number of sources of knowledge of self- determination. Of the 136 correlations, 39 showed strong, positive correlations, 46 showed moderate, positive correlations, and 40 showed weak, positive correlations. For Research Question Three, MANOVA analyses revealed a statistically significant difference between educators working in general education, special education, and related services on the dependent variables of total mean self-reported amount of instruction and mean rating of importance. Special educators (M = 5.17) rated the components of self-determination as significantly more important than general educators (M = 4.92). Related service personnel (M = 4.85) provided instruction in the components of self-determination significantly more often than general (M = 4.20) or special educators (M = 4.45). Research Question Four was used to analyze the responses to five open-response questions and included exploratory analyses. As reflected in their definitions and identified important components of self-determination, the emergent theme of perseverance was identified with much more frequency than the essential characteristics or component behaviors of self-determination. Overall, educators differed on their amount of instruction and ratings of importance of self-determination based on role. They reported they had familiarity with self-determination and identified that it was important, but less than half of the educators believed that schools and educators support instruction in self-determination, and their definitions of self-determination did not strongly align with the operationalized definition of self-determination that supports instruction

Zinc differentially modulates DNA damage induced by anthracyclines in normal and cancer cells

Zinc is one of the most essential trace elements in human organism. Low blood level of zinc is often noted in acute lymphocytic leukemia (ALL). Treatment with zinc adjuvant is hypothesized to accelerate recovery from ALL, and in conjunction with chemotherapy, cure ALL. Aim: We determined the effect of zinc on DNA damage induced by doxorubicin and idarubicin, two anthracyclines used in ALL treatment. Methods: The experiment was performed on acute lymphoblastic leukemia cell line (CCRF-CEM) and lymphocytes from peripheral blood of healthy, adult subjects. To evaluate the level of DNA damage the comet assay in the alkaline version was used. Results: We observed a significant difference in DNA damage level between normal and cancer cells in the presence of zinc. Cancer cells exhibited a significant increase of DNA damage in the presence of zinc, while in lymphocytes no such effect was observed. Conclusion: Our results suggest that zinc may protect normal cells against DNA-damaging action of anthracyclins and increase this action in cancer cells

TALON - The Telescope Alert Operation Network System: Intelligent Linking of Distributed Autonomous Robotic Telescopes

The internet has brought about great change in the astronomical community, but this interconnectivity is just starting to be exploited for use in instrumentation. Utilizing the internet for communicating between distributed astronomical systems is still in its infancy, but it already shows great potential. Here we present an example of a distributed network of telescopes that performs more efficiently in synchronous operation than as individual instruments. RAPid Telescopes for Optical Response (RAPTOR) is a system of telescopes at LANL that has intelligent intercommunication, combined with wide-field optics, temporal monitoring software, and deep-field follow-up capability all working in closed-loop real-time operation. The Telescope ALert Operations Network (TALON) is a network server that allows intercommunication of alert triggers from external and internal resources and controls the distribution of these to each of the telescopes on the network. TALON is designed to grow, allowing any number of telescopes to be linked together and communicate. Coupled with an intelligent alert client at each telescope, it can analyze and respond to each distributed TALON alert based on the telescopes needs and schedule.Comment: Presentation at SPIE 2004, Glasgow, Scotland (UK