Synchrotron source models and the infrared-optical variability of blazars

2005 ◽  
pp. 155-162
Author(s):  
Klaus Meisenheimer
Keyword(s):  
Optical Variability ◽  
Synchrotron Source ◽  
Source Models

scholarly journals Nearly Simultaneous Optical and VLBI Polarization Observations of BL Lac Objects

1996 ◽  
Vol 175 ◽  
pp. 242-243
Author(s):  
D.C. Gabuzda ◽  
P.Y. Kochanev ◽  
M.L. Sitko ◽  
P.S. Smith
Keyword(s):  
Magnetic Field ◽  
Thermal Emission ◽  
Model Parameters ◽  
Bl Lac Objects ◽  
Synchrotron Source ◽  
Bl Lacertae ◽  
Simultaneous Measurements ◽  
Source Models ◽  
Polarization Characteristics ◽  
The Magnetic Field

The continua of BL Lacertae objects and other “blazars” are dominated by nonthermal emission that is variable and highly polarized at UV–radio wavelengths (Angel and Stockman 1980; Kollgaard 1994; Allen et al. 1993). It is believed that this non-thermal emission is associated with the relativistic jets that are known to exist in these sources, but details of the jet structure and physics are still very uncertain. It is usually expected that the polarization behavior at optical and radio wavelengths should show little or no correlation, even if genuinely simultaneous measurements are compared. It is typically thought that the emission in these two wavebands originates in vastly different parts of the source, where the magnetic field geometries are likely to be quite different. In some inhomogeneous synchrotron source models for blazars, however, depending on the model parameters considered, the radio and UV-optical-IR (UVOIR) emission may be co-spatial (Ghisellini, Maraschi & Treves (1985)). It is thus of interest to search for correlations between the emission of blazars in the UVOIR and radio, to test such models. Our approach to doing this has been to compare simultaneous measurements of the optical and VLBI polarization characteristics of compact AGN. The polarization of the radiation is effectively used as a probe of the magnetic field structures in the regions where the emission at the two wavelengths arises.

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

Discovery of the fast optical variability of GRB 080319B and the prospects for wide-field optical monitoring with high time resolution

2010 ◽  
Vol 180 (4) ◽  
pp. 424 ◽  
Author(s):  
G.M. Beskin ◽  
S.V. Karpov ◽  
S.F. Bondar ◽  
V.L. Plokhotnichenko ◽  
A. Guarnieri ◽  
...  
Keyword(s):  
Time Resolution ◽  
High Time ◽  
High Time Resolution ◽  
Optical Variability ◽  
Wide Field ◽  
Optical Monitoring

Texture of submicron Ni-Mn-Ga films studied by X-ray diffraction at the ANKA synchrotron source

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 229-234 ◽  
Author(s):  
V. A. Chernenko ◽  
S. Doyle ◽  
M. Kohl ◽  
P. Müllner ◽  
S. Besseghini ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray

Image Evaluation of the Photophysics Beamline at Indus-1 Synchrotron Source by Ray Tracing

1999 ◽  
Vol 28 (4) ◽  
pp. 145-159
Author(s):  
N. C. Das ◽  
B. N. Raja Sekhar
Keyword(s):  
Ray Tracing ◽  
Image Evaluation ◽  
Synchrotron Source
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