A Spitzer MIPS Study of 2.5-2.0 M\odot Stars in Scorpius-Centaurus

We have obtained Spitzer Space Telescope Multiband Imaging Photometer for Spitzer (MIPS) 24 {\mu}m and 70 {\mu}m observations of 215 nearby, Hipparcos B- and A-type common proper motion single and binary systems in the nearest OB association, Scorpius-Centaurus. Combining our MIPS observations with those of other ScoCen stars in the literature, we estimate 24 {\mu}m B+A-type disk fractions of 17/67 (25+6%), 36/131 (27+4%), and 23/95 (24+5%) for Upper Scorpius (\sim11 Myr), Upper Centaurus Lupus (\sim15 Myr), and Lower Centaurus Crux (\sim17 Myr), respectively, somewhat smaller disk fractions than previously obtained for F- and G-type members. We confirm previous IRAS excess detections and present new discoveries of 51 protoplanetary and debris disk systems, with fractional infrared luminosities ranging from LIR/L\ast = 1e-6 to 1e-2 and grain temperatures ranging from Tgr = 40 - 300 K. In addition, we confirm that the 24 {\mu}m and 70 {\mu}m excesses (or fractional infrared luminosities) around B+A type stars are smaller than those measured toward F+G type stars and hypothesize that the observed disk property dependence on stellar mass may be the result of a higher stellar companion fraction around B- and A-type stars at 10 - 200 AU and/or the presence of Jupiter-mass companions in the disks around F- and G- type stars. Finally, we note that the majority of the ScoCen 24 {\mu}m excess sources also possess 12 {\mu}m excess, indicating that Earth-like planets may be forming via collisions in the terrestrial planet zone at \sim10 - 100 Myr.Comment: 62 pages, 17 figures including 6 colo

Brownian Thermal Noise in Multilayer Coated Mirrors

We analyze the Brownian thermal noise of a multi-layer dielectric coating, used in high-precision optical measurements including interferometric gravitational-wave detectors. We assume the coating material to be isotropic, and therefore study thermal noises arising from shear and bulk losses of the coating materials. We show that coating noise arises not only from layer thickness fluctuations, but also from fluctuations of the interface between the coating and substrate, driven by internal fluctuating stresses of the coating. In addition, the non-zero photoeleastic coefficients of the thin films modifies the influence of the thermal noise on the laser field. The thickness fluctuations of different layers are statistically independent, however, there exists a finite coherence between layers and the substrate-coating interface. Taking into account uncertainties in material parameters, we show that significant uncertainties still exist in estimating coating Brownian noise.Comment: 26 pages, 18 figure

Overview of CFD Analyses Supporting the Reusable Solid Rocket Motor (RSRM) Program at MSFC

During the past year, various computational fluid dynamic (CFD) analyses were performed at Marshall Space Flight Center to support the Reusable Solid Rocket Motor program. The successful completion of these analyses involved application of the CFD codes FDNS and CELMINT. The topics addressed by the analyses were: (1) the design and prediction of slag pool accumulation within the five inch test motor, (2) prediction of slag pool behavior and its response to lateral accelerations, (3) the clogging of potential insulation debonds within the nozzle by slag accumulation, (4) the behavior of jets within small voids inside nozzle joint gaps, (5) The effect of increased inhibitor stiffness on motor acoustics, and (6) the effect of a nozzle defect on particle impingement enhanced erosion. The emphasis of this presentation will be to further discuss the work in topics 3, 4, and 5

A model-based circular binary segmentation algorithm for the analysis of array CGH data

<p>Abstract</p> <p>Background</p> <p>Circular Binary Segmentation (CBS) is a permutation-based algorithm for array Comparative Genomic Hybridization (aCGH) data analysis. CBS accurately segments data by detecting change-points using a maximal-<it>t </it>test; but extensive computational burden is involved for evaluating the significance of change-points using permutations. A recent implementation utilizing a hybrid method and early stopping rules (hybrid CBS) to improve the performance in speed was subsequently proposed. However, a time analysis revealed that a major portion of computation time of the hybrid CBS was still spent on permutation. In addition, what the hybrid method provides is an approximation of the significance upper bound or lower bound, not an approximation of the significance of change-points itself.</p> <p>Results</p> <p>We developed a novel model-based algorithm, extreme-value based CBS (eCBS), which limits permutations and provides robust results without loss of accuracy. Thousands of aCGH data under null hypothesis were simulated in advance based on a variety of non-normal assumptions, and the corresponding maximal-<it>t </it>distribution was modeled by the Generalized Extreme Value (GEV) distribution. The modeling results, which associate characteristics of aCGH data to the GEV parameters, constitute lookup tables (eXtreme model). Using the eXtreme model, the significance of change-points could be evaluated in a constant time complexity through a table lookup process.</p> <p>Conclusions</p> <p>A novel algorithm, eCBS, was developed in this study. The current implementation of eCBS consistently outperforms the hybrid CBS 4× to 20× in computation time without loss of accuracy. Source codes, supplementary materials, supplementary figures, and supplementary tables can be found at <url>http://ntumaps.cgm.ntu.edu.tw/eCBSsupplementary</url>.</p