X-ray Variability and Emission Process of the Radio Jet in M87

We monitored the M87 jet with the ACIS-S detector on Chandra with 5 observations between 2002 Jan and 2002 Jul. Our goal was to determine the presence and degree of variability in morphology, intensity, and spectral parameters. We find strong variability of the core and HST-1, the knot lying 0.8" from the core. These observations were designed to constrain the X-ray emission process: whereas synchrotron emission would necessitate the presence of extremely high energy electrons with a halflife of a few years or less, inverse Compton emission from a relativistic jet would arise from low energy electrons with very long halflives. Currently, all indications point to a synchrotron process for the X-ray emission from the M87 jet. We give key parameters for a ``modest beaming'' synchrotron model.Comment: 4 pages with 2 embedded figures (1 in color). To be published in the proceedings of the Bologna Jet Workshop "The Physics of Relativistic Jets in the CHANDRA and XMM Era", 23-27 September 2002, Brunetti, Harris, Sambruna, and Setti, editors. 2003, New Ast. Re

The Large Scale X-ray Emission from M87

We describe asymmetrical features in a long exposure X-ray map of M87 made with the ROSAT High Resolution Imager (HRI). A bright triangular region is marked by a linear `spur' along one edge. The structure of this spur suggests an interpretation of a tangential view of a shock front 18 kpc long. None of the brighter features are spatially coincident with radio or optical structures so we concur with earlier investigators that most of the emission arises from thermal processes.Comment: 6 pages latex, including 3 postscript figures. Uses psfig and LAMUPHYS (Springer) macro. To be published in 'The M87 Ringberg Workshop', September 1997, Springer Lecture Notes in Physics Series, Roeser and Meisenheimer, ed

X-ray Emission from Extragalactic Jets

This review focuses on the X-ray emission processes of extra-galactic jets on scales resolvable by the sub arcsec resolution of the Chandra X-ray Observatory. It is divided into 4 parts. The introductory chapter reviews the classical problems for jets, as well as those associated directly with the X-ray emission. Throughout this section, we deal with the dualisms of low powered radio sources versus high powered radio galaxies and quasars; synchrotron models versus inverse Compton models; and the distinction between the relativistic plasma responsible for the received radiation and the medium responsible for the transport of energy down the jet. The second part collects the observational and inferred parameters for the currently detected X-ray jets and attempts to put their relative sizes and luminosities in perspective. In part 3, we first give the relevant radio and optical jet characteristics, and then examine the details of the X-ray data and how they can be related to various jet attributes. The last section is devoted to a critique of the two non-thermal emission processes and to prospects for progress in our understanding of jets.Comment: This is a version of a review article to be published (2006 Sep) in the Annual Reviews of Astronomy and Astrophysics, vol. 44, p. 463. 8 of the 12 figures have been removed from the article and are provided as separate jpg files to conserve space. There are 38 pages remaining in the text. Complete postscript and pdf versions are available at: http://hea-www.harvard.edu/~harris/Xjetreview

Effect of sodium bicarbonate and sodium bentonite on digestion and rumen fermentation characteristics of forage sorghum silage-based diets fed to growing steers

One percent sodium bicarbonate (NaHCo3) increased intake of a 50% silage - 50% grain diet, but had no effect on intake of a full-feed sorghum silage diet. The addition of concentrate (rolled milo) slightly lowered rumen pH and decreased acid detergent fiber (ADF) and starch digestion. NaHC03 had no effect on digestibility, but 2% bentonite lowered digestibility of NDF and ADF. Neither compound affected rumen fermentation characteristics.; Dairy Day, 1985, Kansas State University, Manhattan, KS, 1985

Resonantly enhanced nonlinear optics in semiconductor quantum wells: An application to sensitive infrared detection

A novel class of coherent nonlinear optical phenomena, involving induced transparency in quantum wells, is considered in the context of a particular application to sensitive long-wavelength infrared detection. It is shown that the strongest decoherence mechanisms can be suppressed or mitigated, resulting in substantial enhancement of nonlinear optical effects in semiconductor quantum wells.Comment: 4 pages, 3 figures, replaced with revised versio

On the nature of the unidentified X-ray/gamma-ray sources IGR J18027-1455 and IGR J21247+5058

We present a multiwavelength study of the environment of the unidentified X-ray/gamma-ray sources IGR J18027-1455 and IGR J21247+5058, recently discovered by the IBIS/ISGRI instrument, onboard the INTEGRAL satellite. The main properties of the sources found inside their position error circles, give us clues about the nature of these high-energy sources.Comment: 8 pages, 4 figures, Proceedings of the Conference "The Multiwavelength Approach to Unidentified Sources", to appear in the journal Astrophysics and Space Scienc

Human Immunodeficiency Virus (HIV)

Magnetic Resonance Imaging (MRI) for the evaluation of patients infected with human immunodeficiency virus (HIV), as with most other forms of intracranial inflammatory or infectious diseases, is a powerful though largely nonspecific diagnostic tool. For imaging of these complex patients with the varied and numerous pathologies they may harbor, the standard protocol is utilized to include gadolinium‐enhanced sequences. This unit presents optional imaging sequences, including magnetic resonance diffusion (dMRI), magnetic resonance perfusion (pMRI), and magnetic resonance spectroscopy (MRS), that can be employed should patient tolerance allow and if specific the clinical situation requires further clarification.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145277/1/cpmia0403.pd

Strangeness Production and Ultrarelativistic Cascades

A two phase cascade, LUCIFER II, developed for the treatment of ultra high energy ion-ion collisions is applied to the production of strangeness at SPS energies $\sqrt{s}=17-20$. This simulation is able to simultaneously describe both hard processes such as Drell-Yan and slower, soft processes such as the production of light mesons, including strange mesons, by separating the dynamics into two steps, a fast cascade involving only nucleons in the original colliding relativistic ions followed, after an appropriate delay, by multiscattering of the resulting excited baryons and mesons produced virtually in the first step. No energy loss can take place in the short time interval over which the first cascade takes place. The chief result is a reconciliation of the important Drell-Yan measurements with the apparent success of standard cascades to describe the nucleon stopping and meson production in heavy ion experiments at the CERN SPS. A byproduct, obtained here in preliminary calculations, is a description of strangeness production in the collision of massive ions.Comment: 10 pages, 5 figure

Radio Source Heating in the ICM: The Example of Cygnus A

One of the most promising solutions for the cooling flow problem involves energy injection from the central AGN. However it is still not clear how collimated jets can heat the ICM at large scale, and very little is known concerning the effect of radio lobe expansion as they enter into pressure equilibrium with the surrounding cluster gas. Cygnus A is one of the best examples of a nearby powerful radio galaxy for which the synchrotron emitting plasma and thermal emitting intra-cluster medium can be mapped in fine detail, and previous observations have inferred possible shock structure at the location of the cocoon. We use new XMM-Newton observations of Cygnus A, in combination with deep Chandra observations, to measure the temperature of the intra-cluster medium around the expanding radio cavities. We investigate how inflation of the cavities may relate to shock heating of the intra-cluster gas, and whether such a mechanism is sufficient to provide enough energy to offset cooling to the extent observed.Comment: To appear in the Proceedings of "Heating vs. Cooling in Galaxies and Clusters of Galaxies", August 2006, Garching (Germany), Eds. H. Boehringer, G.W. Pratt, A. Finoguenov, P. Schuecker, Springer-Verlag series "ESO Astrophysics Symposia", p.101, in press. 8 pages, 3 multiple figure