The Elemental Composition and the Spatial Distributions of Elements in the Crab Nebula

We present new observations and photoionization calculations for investigating gaseous regions that represent expected nuclear processing in the Crab Nebula supernova remnant. High helium abundance is shown to cause a very efficient [N II] ¸¸6548,6583 emitting zone which can account for some strong nitrogen emission. This high helium abundance causes strong emission of [C I] ¸¸9823,9850. When emission line measurements are compared with model simulations, most of the nebular gas appears to have depleted or solar nitrogen and enhanced carbon. This argues for a precursor star that had a mass greater than 9.5M¯. We also use images of selected emission lines along with photoionization calculations to investigate the overall spatial distribution of elements in the Crab Nebula. We introduce new methods of calibrating direct images, including using existing Fabry-Perot data to take into account the different line-of-sight velocities of each individual filament. After processing, we compare these flux distributions with a large number of numerical model simulations to produce abundance maps of helium, nitrogen, oxygen, and sulfur in the Crab Nebula. These maps show evidence of gas that has undergone Carbon-Nitrogen-Oxygen processing, helium-burning, and oxygen-burning. High sulfur abundances mixed with gas representative of CNO processing were most likely generated from an off-center oxygen flash and then repositioned north and southeast from the pulsar by a relativistic wind. Clear evidence of oxygen burning material in the remnant gives strong support for a precursor star mass near 10M¯

The Crab Nebula's Composition and Precursor Star Mass

We present results of new photoionization calculations for investigating gaseous regions that represent potentially expected stages of nuclear processing in the Crab Nebula supernova remnant. In addition to gas resulting from CNO-processing and oxygen-burning, as previously reported, a large component of the nebula appears to be carbon-rich. These results suggest that the precursor star had an initial mass of 9.5 solar masses or more.Comment: manuscript in AASTeX, 6 figures in .eps, submitted to Astronomical Journa

Reading handwritten digits: a ZIP code recognition system

A neural network algorithm-based system that reads handwritten ZIP codes appearing on real US mail is described. The system uses a recognition-based segmenter, that is a hybrid of connected-components analysis (CCA), vertical cuts, and a neural network recognizer. Connected components that are single digits are handled by CCA. CCs that are combined or dissected digits are handled by the vertical-cut segmenter. The four main stages of processing are preprocessing, in which noise is removed and the digits are deslanted, CCA segmentation and recognition, vertical-cut-point estimation and segmentation, and directly lookup. The system was trained and tested on approximately 10000 images, five- and nine-digit ZIP code fields taken from real mail

Large meta-analysis of genome-wide association studies identifies five loci for lean body mass

Lean body mass, consisting mostly of skeletal muscle, is important for healthy aging. We performed a genome-wide association study for whole body (20 cohorts of European ancestry with n = 38,292) and appendicular (arms and legs) lean body mass (n = 28,330) measured using dual energy X-ray absorptiometry or bioelectrical impedance analysis, adjusted for sex, age, height, and fat mass. Twenty-one single-nucleotide polymorphisms were significantly associated with lean body mass either genome wide (p < 5 x 10(-8)) or suggestively genome wide (p < 2.3 x 10(-6)). Replication in 63,475 (47,227 of European ancestry) individuals from 33 cohorts for whole body lean body mass and in 45,090 (42,360 of European ancestry) subjects from 25 cohorts for appendicular lean body mass was successful for five single-nucleotide polymorphisms in/ near HSD17B11, VCAN, ADAMTSL3, IRS1, and FTO for total lean body mass and for three single-nucleotide polymorphisms in/ near VCAN, ADAMTSL3, and IRS1 for appendicular lean body mass. Our findings provide new insight into the genetics of lean body mass