492 research outputs found
Simulated VLBI Images From Relativistic Hydrodynamic Jet Models
A series of simulated maps showing the appearance in total intensity of flows
computed using a recently developed relativistic hydrodynamic code (Duncan \&
Hughes 1994: ApJ, 436, L119) are presented. The radiation transfer calculations
were performed by assuming the flow is permeated by a magnetic field and fast
particle distribution in energy equipartition, with energy density proportional
to the hydrodynamic energy density (i.e., pressure). We find that relativistic
flows subject to strong perturbations exhibit a density structure consisting of
a series of nested bow shocks, and that this structure is evident in the
intensity maps for large viewing angles. However, for viewing angles
, differential Doppler boosting leads to a series of axial knots
of emission, similar to the pattern exhibited by many VLBI sources. The
appearance of VLBI knots is determined primarily by the Doppler boosting of
parts of a more extended flow. To study the evolution of a perturbed jet, a
time series of maps was produced and an integrated flux light curve created.
The light curve shows features characteristic of a radio loud AGN: small
amplitude variations and a large outburst. We find that in the absence of
perturbations, jets with a modest Lorentz factor () exhibit complex
intensity maps, while faster jets (Lorentz factor ) are largely
featureless. We also study the appearance of kiloparsec jet-counterjet pairs by
producing simulated maps at relatively large viewing angles; we conclude that
observed hot spot emission is more likely to be associated with the Mach disk
than with the outer, bow shock.Comment: 27 pages, uses aasms4.sty; 18 PostScript figures (1.57Mb gziped,
8.67Mb gunziped) available from
http://www.astro.lsa.umich.edu/users/hughes/icon_dir/rad.html or by anonymous
ftp from ra.astro.lsa.umich.edu in pub/get/hughes. Submitted to Ap.
Supplement 20, Part 3, Parasite-Subject Catalogue: Parasites: Trematoda and Cestoda
United States Department of Agriculture, Bureau of Animal Industr
Perspectives and limitations of gene expression profiling in rheumatology: new molecular strategies
The deciphering of the sequence of the human genome has raised the expectation of unravelling the specific role of each gene in physiology and pathology. High-throughput technologies for gene expression profiling provide the first practical basis for applying this information. In rheumatology, with its many diseases of unknown pathogenesis and puzzling inflammatory aspects, these advances appear to promise a significant advance towards the identification of leading mechanisms of pathology. Expression patterns reflect the complexity of the molecular processes and are expected to provide the molecular basis for specific diagnosis, therapeutic stratification, long-term monitoring and prognostic evaluation. Identification of the molecular networks will help in the discovery of appropriate drug targets, and permit focusing on the most effective and least toxic compounds. Current limitations in screening technologies, experimental strategies and bioinformatic interpretation will shortly be overcome by the rapid development in this field. However, gene expression profiling, by its nature, will not provide biochemical information on functional activities of proteins and might only in part reflect underlying genetic dysfunction. Genomic and proteomic technologies will therefore be complementary in their scientific and clinical application
Supplement 18, Part 4, Parasite-Subject Catalogue: Parasites: Nematoda And Acanthocephala
United States Department of Agriculture, Bureau of Animal Industry, National Animal Parasite Laboratory, Veterinary Sciences Research Division, Agricultural Research Servic
Supplement 18, Part 3, Parasite-Subject Catalogue: Parasites: Trematoda And Cestoda
United States Department of Agriculture, Bureau of Animal Industry, National Animal Parasite Laboratory, Veterinary Sciences Research Division, Agricultural Research Servic
Supplement 17, Part 6, Parasite-Subject Catalogue: Subject Headings And Treatment
United States Department of Agriculture, Bureau of Animal Industry, National Animal Parasite Laboratory, Veterinary Sciences Research Division, Agricultural Research Servic
Supplement 19, Part 4, Parasite-Subject Catalogue: Parasites: Nematoda and Acanthocephala
United States Department of Agriculture, Bureau of Animal Industry, Animal Parasitology Institute, Agricultural Research Servic
Retention period differentially attenuates win–shift/lose–stay relative to win–stay/lose–shift performance in the rat
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