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XMM-Newton and Chandra have ushered in a new era for the study of dwarf galaxies in the Local Group. We provide an overview of the opportunities, challenges, and some early results. The large number of background sources relative to galaxy sources is a major theme. Despite this challenge, the identification of counterparts has been possible, providing hints(More)
We present correlations of extent of temporal lobectomy for intractable epilepsy with postoperative memory changes (20 cases) and abnormalities of visual field and neurologic examination (45 cases). Postoperative magnetic resonance imaging (MRI) in the coronal plane was used to quantify anteroposterior extent of resection of various quadrants of the(More)
Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion.(More)
We present Chandra observations of black hole X-ray novae V404 Cyg, A0620–00, GRO J1655–40 and XTE J1550–564 in quiescence. Their quiescent spectra can be well fitted by a power-law model with number slope α ∼ 2. While a coronal (Raymond-Smith) model is also a statistically acceptable representation of the spectra , the best fit temperatures of these models(More)
One criticism of neural network controllers (neuro-controllers) is that the analytical model of the controller is not defined; therefore contemporary optimization techniques in control systems cannot be applied to the closed loop system. Often control parameters are tuned online because of inaccuracies due to linearity assumptions and reduction of order.(More)
We have obtained snapshot images of an X-ray nova in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The Chandra position of the X-ray nova was R. During this time period, the X-ray flux decayed linearly from (3.6±0.2)×10 −4 to <(6.9±0.09)×10 −5 ct cm −2 s −1. The HST identification of an optical source in the(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. ABSTRACT We report on the Chandra X-ray Observatory and Hubble Space(More)
We analyze data from five Chandra observations of the spiral galaxy NGC 6946, and from three Chandra observations of the irregular/spiral interacting galaxy pair NGC 4485/4490, with an emphasis on investigating the long-term variability exhibited by the source populations. We detect 90 point sources coincident with NGC 6946 down to luminosities of a few(More)