373 research outputs found
Sharp spectral stability estimates via the Lebesgue measure of domains for higher order elliptic operators
We prove sharp stability estimates for the variation of the eigenvalues of
non-negative self-adjoint elliptic operators of arbitrary even order upon
variation of the open sets on which they are defined. These estimates are
expressed in terms of the Lebesgue measure of the symmetric difference of the
open sets. Both Dirichlet and Neumann boundary conditions are considered
Maximal, potential and singular operators in the local "complementary" variable exponent Morrey type spaces
We consider local "complementary" generalized Morrey spaces M-c({x0})p(.).omega (Omega) in which the p-means of function are controlled over Omega \ B(x(0), r) instead of B(x(0), r), where Omega subset of R-n is a bounded open set, p(x) is a variable exponent, and no monotonicity type condition is imposed onto the function omega(r) defining the "complementary" Morrey-type norm. In the case where omega is a power function, we reveal the relation of these spaces to weighted Lebesgue spaces. In the general case we prove the boundedness of the Hardy-Littlewood maximal operator and Calderon-Zygmund singular operators with standard kernel, in such spaces. We also prove a Sobolev type M-c({x0})p(.).omega (Omega) -> M-c({x0})p(.).omega (Omega)-theorem for the potential operators I-alpha(.), also of variable order. In all the cases the conditions for the boundedness are given it terms of Zygmund-type integral inequalities-on omega(r), which do not assume any assumption on monotonicity of omega(r).Science Development Foundation under the President of the Republic of Azerbaijan [EIF-2010-1(1)-40/06-1]; Scientific and Technological Research Council of Turkey (TUBITAK) [110T695]info:eu-repo/semantics/publishedVersio
Possibly interacting Vorontsov-Velyaminov galaxies. I. Observations of VV432, VV543 and VV747
Among the galaxies which were included in the Atlas and Catalogue of
Interacting galaxies by Vorontsov-Velyaminov (hereafter VV) as multiple systems
("nests", "chains" and similarly looking systems), there are many objects,
where the interaction is not evident. Some of them are single objects,
including low-mass galaxies with active star formation (SF). In this work we
present the description of observations and results of the long-slit
spectrophotometry with the Russian 6-m telescope of three VV-galaxies looking
like double or multiple systems, and HI-observations of one of them in order to
elucidate their nature, determine their metallicity, kinematic properties and
the evolution status. Galaxies VV432 and VV747 are found to be dwarf systems
with low oxygen abundance (O/H = 1/22 and 1/12 of the solar value,
respectively). Their velocity curves indicate quite slow rotation with
respective maximum velocities of about 60 and 80 km/s, in agreement with their
low luminosities. The distance to VV432 is rather uncertain. If it is a member
of Virgo Cluster, this is the most metal-deficient known galaxy of this
aggregate. For galaxy VV543 the measured emission-line redshift 0.047 appeared
ten times larger than it was given in the original paper and is cited in
databases. This "system" evidently represents an optical pair of two galaxies
with large velocity difference. The fainter western component is an HII-galaxy,
while the brighter one is an absorption-line early-type galaxy with the radial
velocity being 1600 km/s lower.Comment: 11 pages, A&AS in press. Version of the paper with Figures 1-3 of the
higher quality is available via
http://precise.sao.ru/Laboratory/Publications/2000_pub.htm
Analyticity and criticality results for the eigenvalues of the biharmonic operator
We consider the eigenvalues of the biharmonic operator subject to several
homogeneous boundary conditions (Dirichlet, Neumann, Navier, Steklov). We show
that simple eigenvalues and elementary symmetric functions of multiple
eigenvalues are real analytic, and provide Hadamard-type formulas for the
corresponding shape derivatives. After recalling the known results in shape
optimization, we prove that balls are always critical domains under volume
constraint.Comment: To appear on the proceedings of the conference "Geometric Properties
for Parabolic and Elliptic PDE's - 4th Italian-Japanese Workshop" held in
Palinuro (Italy), May 25-29, 201
Tunneling of polarized fermions in 3D double wells
We study the tunneling of a spin polarized Fermi gas in a three-dimensional
double well potential, focusing on the time dynamics starting from an initial
state in which there is an imbalance in the number of particles in the two
wells. Although fermions in different doublets of the double well tunnel with
different frequencies, we point out that (incoherent) oscillations of a large
number of particles can arise, as a consequence of the presence of transverse
degrees of freedom. Estimates of the doublet structure and of the occupation of
transverse eigenstates for a realistic experimental setup are provided.Comment: 10 pages, Typos corrected and figures changed - published in Laser
Physics, issue on the LPHYS'11 conference (Sarajevo, 2011
Discovery of a massive variable star with Z=Zo/36 in the galaxy DDO 68
The Local Volume dwarf galaxy DDO 68, from the spectroscopy of its two
brightest HII regions (Knots 1 and 2) was designated as the second most
metal-poor star-forming galaxy [12+log(O/H)=7.14]. In the repeated spectral
observations in 2008 January with the 6-m telescope (BTA) of the HII region
Knot 3 [having 12+log(O/H)=7.10+-0.06], we find a strong evidence of a
transient event related to a massive star evolution. From the follow-up
observation with the higher spectral resolution in 2008 February, we confirm
this phenomenon, and give parameters of its emission-line spectrum comprising
of Balmer HI and HeI lines. The luminosities of the strongest transient lines
(Ha, Hb) are of a few 10^36 erg s^-1. We also detected an additional continuum
component in the new spectrum of Knot 3, which displays the spectral energy
distribution raising to ultraviolet. The estimate of the flux of this continuum
leads us to its absolute V-band magnitude of ~-7.1. Based on the spectral
properties of this transient component, we suggest that it is related to an
evolved massive star of luminous blue variable type with Z=Zo/36. We briefly
discuss observational constraints on parameters of this unique (in the aspect
of the record low metallicity of the progenitor massive star) event and propose
several lines of its study.Comment: 6 pages, 5 Postscript figures, to appear in MNRAS Letters in June
2008 issu
Long term variability of the Broad Emission Line profiles in AGN
Results of a long-term monitoring ( years) of the broad line and
continuum fluxes of three Active Galactic Nuclei (AGN), 3C 390.3, NGC 4151, and
NGC 5548, are presented. We analyze the H and H profile
variations during the monitoring period and study different details (as bumps,
absorption bands) which can indicate structural changes in the Broad Line
Region (BLR). The BLR dimensions are estimated using the time lags between the
continuum and the broad lines flux variations. We find that in the case of 3C
390.3 and NGC 5548 a disk geometry can explain both the broad line profiles and
their flux variations, while the BLR of NGC 4151 seems more complex and is
probably composed of two or three kinematically different regions.Comment: 10 pages, 9 figures, New Astronomy Reviews (Proceeding of 7th
SCSLSA), in pres
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