6 research outputs found
Study of the Structure of the Coma Cluster Based on a Hierarchical Powerful Clustering Method
Six subclusters in the Coma cluster have been selected on the basis of a
hierarchical clustering method that takes the gravitational interaction among
galaxies into account. Of these, three main subclusters around the galaxies NGC
4889, NGC 4874, and NGC 4839 have been singled out. We have used the objective
statistical criterion applied by Vennik and Anosova in studies of close groups
of galaxies to evaluate each member included in a subcluster with a high
probability. Galaxies with a significant deficit of hydrogen HI, including
objects from the Bravo-Alfaro list,have been identified with members of the
subclusters, with the greatest number of them in the subclusters around NGC
4874 and NGC 4839. A quantitative estimate of the hydrogen deficit using the HI
index in the RCG3 catalog reveals a statistically significant excess value for
those galaxies that are members of the subclusters compared to the field
galaxies with a hydrogen deficit in the studied area of Coma cluster. A
substantial number of the spiral galaxies with a hydrogen deficit in the
subclusters turned out to be radio galaxies as well.Comment: This is a revised version of the paper, published in
"Astrophysics",vol.48, no 4, 200
Structure of the Galaxies in the NGC 80 Group
BV-bands photometric data obtained at the 6-m telescope of the Special
Astrophysical Observatory are used to analyze the structure of 13 large disk
galaxies in the NGC 80 group. Nine of the 13 galaxies under consideration are
classified by us as lenticular galaxies. The stellar populations in the
galaxies are very different, from old ones with ages of T>10 Gyrs (IC 1541) to
relatively young, with the ages of T<2-3 Gyr (IC 1548, NGC 85). In one case,
current star formation is known (UCM 0018+2216). In most of the galaxies, more
precisely in all of them more luminous than M(B) -18, two-tiered
(`antitruncated') stellar disks are detected, whose radial surface brightness
profiles can be fitted by two exponential segments with different scalelengths
-- shorter near the center and longer at the periphery. All dwarf S0 galaxies
with single-scalelength exponential disks are close companions to giant
galaxies. Except for this fact, no dependence of the properties of S0 galaxies
on distance from the center of the group is found. Morphological traces of
minor merger are found in the lenticular galaxy NGC 85. Basing on the last two
points, we conclude that the most probable mechanisms for the transformation of
spirals into lenticular galaxies in groups are gravitational ones, namely,
minor mergers and tidal interactions.Comment: 24 pages, 9 figures, slightly improved version of the paper published
in the December, 2009, issue of the Astronomy Report
Flattening of Galaxies of Different Morphological Types in Subclusters of Coma
The dependence of flattening of galaxies on the density of galaxies in
subclusters selected around galaxies NGC4889, NGC4874 and NGC4839 in the Coma
cluster has been studied. The mean values of observed ratios of galaxy
diameters and histograms of their distributions indicate that in the central,
dense regions of subclusters E and S0 type galaxies are close to spheroidals.
Spiral galaxies in subcllusters are found with a hydrogen deficit that about 5
times exceeds the hydrogen deficit in spirals within the halo of the Coma
cluster. Most of spirals with a hydrogen deficit in the subcluster around NGC
4874 according to their 3-D coordinates are located closer to the south-east
edge of this subcluster near an extended gas filament in the x-ray region. This
may indicate over the move of this subcluster toward the central condensation
of faint galaxies in the Coma cluster for a possible merge with it.Comment: This material is a slightly corrected version of an article published
in the "Astrophysics", Vol. 50, No. 3, 2007
Distribution of Spiral Galaxies in the Virgo and Fornax Clusters and Their Dynamic Features
Proposed Guidelines for the Diagnosis and Management of Methylmalonic and Propionic Acidemia
Methylmalonic and propionic acidemia (MMA/PA) are inborn errors of metabolism characterized by accumulation of propionic acid and/or methylmalonic acid due to deficiency of methylmalonyl-CoA mutase (MUT) or propionyl-CoA carboxylase (PCC). MMA has an estimated incidence ofâ~â1: 50,000 and PA ofâ~â1:100â000 -150,000. Patients present either shortly after birth with acute deterioration, metabolic acidosis and hyperammonemia or later at any age with a more heterogeneous clinical picture, leading to early death or to severe neurological handicap in many survivors. Mental outcome tends to be worse in PA and late complications include chronic kidney disease almost exclusively in MMA and cardiomyopathy mainly in PA. Except for vitamin B12 responsive forms of MMA the outcome remains poor despite the existence of apparently effective therapy with a low protein diet and carnitine. This may be related to under recognition and delayed diagnosis due to nonspecific clinical presentation and insufficient awareness of health care professionals because of disease rarity., These guidelines aim to provide a trans-European consensus to guide practitioners, set standards of care and to help to raise awareness. To achieve these goals, the guidelines were developed using the SIGN methodology by having professionals on MMA/PA across twelve European countries and the U.S. gather all the existing evidence, score it according to the SIGN evidence level system and make a series of conclusive statements supported by an associated level of evidence. Although the degree of evidence rarely exceeds level C (evidence from non-analytical studies like case reports and series), the guideline should provide a firm and critical basis to guide practice on both acute and chronic presentations, and to address diagnosis, management, monitoring, outcomes, and psychosocial and ethical issues. Furthermore, these guidelines highlight gaps in knowledge that must be filled by future research. We consider that these guidelines will help to harmonize practice, set common standards and spread good practices, with a positive impact on the outcomes of MMA/PA patients.PubMedWoSScopu