brain mr images tissue segmentation is one of the most important parts of the clinical diagnostic tools. pixel classification methods have been frequently used in the image segmentation with two supervised and unsupervised approaches up to now. supervised segmentation methods lead to high accuracy but they need a large amount of labeled data, which is hard, expensive and slow to obtain. moreove...

In Hall (2002) I reported that 2MASSI J1315309−264951 is an L dwarf with strong Hα emission. Two spectroscopic epochs appeared to show that the Hα was variable, decreasing from 121 Å to 25 Å EW, which I interpreted as a flare during the first observation. Gizis (2002) independently discovered this object, and his intermediate spectroscopic epoch shows Hα with 97 Å EW. A new fourth epoch of spec...

Bright emission nebulae, or HII regions, around hot stars are readily seen in Hα light. However, the all-pervasive faint Hα emission has only recently been detected and mapped over the whole sky. Mostly the Hα emission observed along a line of sight is produced by ionised gas in situ. There are, however, cases where all or most of the Hα radiation is due to scattering by electrons or dust parti...

We present deep Hα imaging of three nearby dwarf galaxies, carefully selected to optimize observations with the Maryland-Magellan Tunable Filter (MMTF) on the Magellan 6.5m telescope. An effective bandpass of ∼13Å is used, and the images reach 3σ flux limits of ∼8×10−18 ergs s−1 cm−2, which is about an order of magnitude lower than standard narrowband observations obtained by the most recent ge...

A remarkable correlation between the Hα emission line and the radio behaviour of LS I+61◦303 over its ∼4 yr modulation is discovered. The radio outburst peak is shifted by a quarter of the ∼4 yr modulat ion period (about 400 days) with respect to the equivalent width of the Hα emission line variability. The onset of the LS I+61◦303 radio outbursts varies in phase with the changes of the Hα emis...

The first observations of the recently completed Wisconsin H-Alpha Mapper (WHAM) facility include a study of emission lines from high velocity clouds in the M, A, and C complexes, with most of the observations on the M I cloud. We present results including clear detections of Hα emission from all three complexes with intensities ranging from 0.06 to 0.20 R. In every observed direction where the...

A sample of over 1000 objects selected from a 1.4 GHz survey made by the Australia Telescope Compact Array (ATCA) is used to study the properties of the faint radio source population. The sample, covering an area of ≈ 3 deg, is 50% complete to 0.2 mJy. Over 50% of the radio sources are found to have optical counterparts brighter then R ≈ 21.5. Spectroscopic observations of 249 optically identif...

The concepts of robust classification and intelligently controlling the search process of genetic algorithm (GA) are introduced and integrated with a conventional genetic classifier for development of a new version of it, which is called Intelligent and Robust GA-classifier (IRGA-classifier). It can efficiently approximate the decision hyperplanes in the feature space. It is shown experime...

Abstract Using a currently most representative sample of 477 late-type galaxies within 11 Mpc the Milky Way with measured star-formation rates (SFRs) from far ultraviolet (FUV) and Hα emission line fluxes, we select extreme ratios: SFR(Hα)/SFR(FUV) > 2 < 1/20. Each subsample amounts to ∼5% total number consists dwarf stellar masses M*/M⊙ = (5.5 − 9.5) dex. In spite huge difference...

We have used a sample of 43 star-forming galaxies imaged in the far-ultraviolet (FUV) by the UIT supplemented with 33 galaxies observed by FAUST, to explore the consistency of UV and Hα derived star formation rates (SFRs). We find, even before correction for dust, that UV and Hα SFRs are quantitatively consistent for low-luminosity galaxies, and that higher luminosity galaxies have Hα SFRs a fa...