5,648 research outputs found
Stability in controlled L-theory
We prove a squeezing/stability theorem for delta-epsilon controlled L-groups
when the control map is a fibration on a finite polyhedron. A relation with
boundedly-controlled L-groups is also discussed.Comment: This is the version published by Geometry & Topology Monographs on 22
April 200
Stability of the Accretion Flows with Stalled Shocks in Core-Collapse Supernovae
Bearing in mind the application to the theory of core-collapse supernovae, we
performed a global linear analysis on the stability of spherically symmetric
accretion flows through a standing shock wave onto a proto neutron star. As
unperturbed flows, we adopted the spherically symmetric steady solutions to the
Euler equations obtained with realistic equation of state and formulae for
neutrino reaction rates taken into account. Then we solved the equations for
linear perturbations numerically, and obtained the eigen frequencies and eigen
functions. We found (1) the flows are stable for all modes if the neutrino
luminosity is lower than ergs/s for
. (2) For larger luminosities, the non-radial
instabilities are induced, probably via the advection-acoustic cycles.
Interestingly, the modes with and 3 become unstable at first for
relatively low neutrino luminosities, e.g. ergs/s
for the same accretion rate, whereas the mode is the most unstable for
higher luminosities, ergs/s. These are all oscillatory
modes. (3) For still larger luminosities, ergs/s for
, non-oscillatory modes, both radial and
non-radial, become unstable. These non-radial modes were identified as
convection. We confirmed the results obtained by numerical simulations that the
instabilities induced by the advection-acoustic cycles are more important than
the convection for lower neutrino luminosities.Comment: 46 pages, 19 figures, Accepted by Ap
The Emergence of El-Ni\~{n}o as an Autonomous Component in the Climate Network
We construct and analyze a climate network which represents the
interdependent structure of the climate in different geographical zones and
find that the network responds in a unique way to El-Ni\~{n}o events. Analyzing
the dynamics of the climate network shows that when El-Ni\~{n}o events begin,
the El-Ni\~{n}o basin partially loses its influence on its surroundings. After
typically three months, this influence is restored while the basin loses almost
all dependence on its surroundings and becomes \textit{autonomous}. The
formation of an autonomous basin is the missing link to understand the
seemingly contradicting phenomena of the afore--noticed weakening of the
interdependencies in the climate network during El-Ni\~{n}o and the known
impact of the anomalies inside the El-Ni\~{n}o basin on the global climate
system.Comment: 5 pages,10 figure
XMM-Newton Observation of IC 310 in the Outer Region of the Perseus Cluster of Galaxies
We present results from an XMM-Newton observation of the head-tail radio
galaxy IC 310 located in the southwest region of the Perseus cluster. The
spectrum is well-fitted by an absorbed power-law model with a photon index of
with no significant absorption excess. The X-ray image shows a
point-like emission at IC 310 without any signs of a structure correlated with
the radio halo tail. The temperature of the intracluster medium surrounding IC
310 declines as a function of distance from the cluster center, from keV in the northeast corner of the field of view to about 3 keV in the
southwest region. Although we do not find any sharp edges in the surface
brightness profile, a brightness excess over a smooth model by about
20% is seen. The temperature also rises by about 10% in the same region. This
indicates that the IC 310 region is a subcluster probably infalling into the
Perseus cluster, and the gas in front of IC 310 towards the Perseus cluster is
likely to be compressed by the large-scale motion, which supports the view that
the IC 310 system is undergoing a merger.Comment: 7 pages, 8 figures (including color), accepted for publication in
PAS
Pressure-induced metal-insulator transition in LaMnO3 is not of Mott-Hubbard type
Calculations employing the local density approximation combined with static
and dynamical mean-field theories (LDA+U and LDA+DMFT) indicate that the
metal-insulator transition observed at 32 GPa in paramagnetic LaMnO3 at room
temperature is not a Mott-Hubbard transition, but is caused by orbital
splitting of the majority-spin eg bands. For LaMnO3 to be insulating at
pressures below 32 GPa, both on-site Coulomb repulsion and Jahn-Teller
distortion are needed.Comment: 4 pages, 3 figure
A Generalized Preferential Attachment Model for Business Firms Growth Rates: II. Mathematical Treatment
We present a preferential attachment growth model to obtain the distribution
of number of units in the classes which may represent business firms
or other socio-economic entities. We found that is described in its
central part by a power law with an exponent which depends on
the probability of entry of new classes, . In a particular problem of city
population this distribution is equivalent to the well known Zipf law. In the
absence of the new classes entry, the distribution is exponential. Using
analytical form of and assuming proportional growth for units, we derive
, the distribution of business firm growth rates. The model predicts that
has a Laplacian cusp in the central part and asymptotic power-law tails
with an exponent . We test the analytical expressions derived using
heuristic arguments by simulations. The model might also explain the
size-variance relationship of the firm growth rates.Comment: 19 pages 6 figures Applications of Physics in Financial Analysis,
APFA
Orbital order and spin-orbit coupling in BaVS3
The correlated 3d sulphide BaVS3 undergoes a sequence of three symmetry
breaking transitions which are reflected in the temperature dependence of the
magnetic susceptibility, and its anisotropy. We introduce a microscopic model
based on the coexistence of wide band a(1g) and localized e(g) d-electrons, and
give the classification of the order parameters under the double space group
and time reversal symmetries. Allowing for the relativistic spin-orbit
coupling, the d-shell multipoles acquire a mixed spin-orbital character. It
follows that orbital ordering is accompanied by a change in the susceptibility
anisotropyComment: 2 pages, submitted to the SCES05 conference, uses elsart41.cl
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