Kyoto Encyclopedia of Genes and Genomes (KEGG) is a knowledge base for systematic analysis of gene functions in terms of the networks of genes and molecules. The major component of KEGG is the PATHWAY database that consists of graphical diagrams of biochemical pathways including most of the known metabolic pathways and some of the known regulatory pathways. The pathway information is also represented by the ortholog group tables summarizing orthologous and paralogous gene groups among different organisms. KEGG maintains the GENES database for the gene catalogs of all organisms with complete genomes and selected organisms with partial genomes, which are continuously re-annotated, as well as the LIGAND database for chemical compounds and enzymes. Each gene catalog is associated with the graphical genome map for chromosomal locations that is represented by Java applet. In addition to the data collection efforts, KEGG develops and provides various computational tools, such as for reconstructing biochemical pathways from the complete genome sequence and for predicting gene regulatory networks from the gene expression profiles. The KEGG databases are daily updated and made freely available (http://www.genome.ad.jp/kegg/).
We have performed self-consistent 2.5-dimensional nonsteady MHD numerical simulations of jet formation, including the dynamics of accretion disks. Although the previous nonsteady MHD simulations for astrophysical jets revealed that the characteristics of nonsteady jets are very similar to those of steady jets, the calculation time of these simulations is very short compared with the time scale of observed jets. Thus we have investigated long term evolutions of the mass accretion rate (Ṁ a), mass outflow rate (Ṁw), and energy of the toroidal magnetic field (E mgt). We found that the jet is ejected intermittently with a period of around 2π which is similar to the growth time of the magnetorotational instability (MRI). §1. IntroductionAlthough the acceleration and collimation mechanisms of the astrophysical jets are still not well understood, these objects are believed to have accretion disks in their central regions. One of the most promising models for jet formation is magnetic acceleration from accretion disks (Blandford 1993). Blandford and Payne (1982) pointed out that a magneto-centrifugally driven outflow from a Keplerian disk is possible if the angle between the disk surface and the poloidal component of the magnetic field is less than 60 • . In order to have access to the observed time scale of jets and to determine whether jet formation becomes a quasi-steady state, we performed long term nonsteady 2.5-dimensional MHD simulations of jets. We also wish to determine whether the time averaged physical quantities have the same characteristics as those found in the steady state model and previous simulations. §2. Assumptions and numerical method Our simulations incorporate the following assumptions: (1) axial symmetry around the rotational axis (∂/∂ϕ = 0) including the azimuthal components of a velocity field (v ϕ ) and a magnetic field (B ϕ ); (2) ideal MHD; (3) an inviscid perfect gas with a specific heat ratio of γ = 5/3; (4) a point-mass gravitational potential. The numerical schemes we use are the cubic interpolated propagation (CIP) method (Yabe et al. 1991) and the method of characteristics-constrained transport (MOCCT) (Stone and Norman 1992). The magnetic induction equation is solved using MOCCT and the others using CIP. §3. Results and conclusionsIn the early stage of evolution, a torsional Alfven wave is generated at the disk surface. This wave propagates up into the corona. Since this wave extracts angular at State Univ NY at Stony Brook on June 30, 2015 http://ptps.oxfordjournals.org/ Downloaded from
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