18,974 research outputs found
Edge scaling limits for a family of non-Hermitian random matrix ensembles
A family of random matrix ensembles interpolating between the GUE and the
Ginibre ensemble of matrices with iid centered complex Gaussian
entries is considered. The asymptotic spectral distribution in these models is
uniform in an ellipse in the complex plane, which collapses to an interval of
the real line as the degree of non-Hermiticity diminishes. Scaling limit
theorems are proven for the eigenvalue point process at the rightmost edge of
the spectrum, and it is shown that a non-trivial transition occurs between
Poisson and Airy point process statistics when the ratio of the axes of the
supporting ellipse is of order . In this regime, the family of
limiting probability distributions of the maximum of the real parts of the
eigenvalues interpolates between the Gumbel and Tracy-Widom distributions.Comment: 44 page
Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions
The internally electrodynamic (IED) particle model was derived based on
overall experimental observations, with the IED process itself being built
directly on three experimental facts, a) electric charges present with all
material particles, b) an accelerated charge generates electromagnetic waves
according to Maxwell's equations and Planck energy equation and c) source
motion produces Doppler effect. A set of well-known basic particle equations
and properties become predictable based on first principles solutions for the
IED process; several key solutions achieved are outlined, including the de
Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass,
Einstein mass-energy relation, Newton's law of gravity, single particle self
interference, and electromagnetic radiation and absorption; these equations and
properties have long been broadly experimentally validated or demonstrated. A
specific solution also predicts the Doebner-Goldin equation which emerges to
represent a form of long-sought quantum wave equation including gravity. A
critical review of the key experiments is given which suggests that the IED
process underlies the basic particle equations and properties not just
sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200
Constrained simulations of the Antennae Galaxies: Comparison with Herschel-PACS observations
We present a set of hydro-dynamical numerical simulations of the Antennae
galaxies in order to understand the origin of the central overlap starburst.
Our dynamical model provides a good match to the observed nuclear and overlap
star formation, especially when using a range of rather inefficient stellar
feedback efficiencies (0.01 < q_EoS < 0.1). In this case a simple conversion of
local star formation to molecular hydrogen surface density motivated by
observations accounts well for the observed distribution of CO. Using radiative
transfer post-processing we model synthetic far-infrared spectral energy
distributions (SEDs) and two-dimensional emission maps for direct comparison
with Herschel-PACS observations. For a gas-to-dust ratio of 62:1 and the best
matching range of stellar feedback efficiencies the synthetic far-infrared SEDs
of the central star forming region peak at values of ~65 - 81 Jy at 99 - 116
um, similar to a three-component modified black body fit to infrared
observations. Also the spatial distribution of the far-infrared emission at 70
um, 100 um, and 160 um compares well with the observations: >50% (> 35%) of the
emission in each band is concentrated in the overlap region while only < 30% (<
15%) is distributed to the combined emission from the two galactic nuclei in
the simulations (observations). As a proof of principle we show that parameter
variations in the feedback model result in unambiguous changes both in the
global and in the spatially resolved observable far-infrared properties of
Antennae galaxy models. Our results strengthen the importance of direct,
spatially resolved comparative studies of matched galaxy merger simulations as
a valuable tool to constrain the fundamental star formation and feedback
physics.Comment: 17 pages, 8 figures, 4 tables, submitted to MNRAS, including
revisions after first referee report, comments welcom
Cyclotron resonance lineshape in a Wigner crystal
The cyclotron resonance absorption spectrum in a Wigner crystal is
calculated. Effects of spin-splitting are modelled by substitutional disorder,
and calculated in the coherent potential approximation. Due to the increasing
strength of the dipole-dipole interaction, the results show a crossover from a
double-peak spectrum at small filling factors to a single-peak spectrum at
filling factors \agt 1/6. Radiation damping and magnetophonon scattering can
also influence the cyclotron resonance. The results are in very good agreement
with experiments.Comment: 4 pages REVTEX, attempt to append 3 figures that seem to have been
lost last tim
Applications and generalizations of Fisher-Hartwig asymptotics
Fisher-Hartwig asymptotics refers to the large form of a class of
Toeplitz determinants with singular generating functions. This class of
Toeplitz determinants occurs in the study of the spin-spin correlations for the
two-dimensional Ising model, and the ground state density matrix of the
impenetrable Bose gas, amongst other problems in mathematical physics. We give
a new application of the original Fisher-Hartwig formula to the asymptotic
decay of the Ising correlations above , while the study of the Bose gas
density matrix leads us to generalize the Fisher-Hartwig formula to the
asymptotic form of random matrix averages over the classical groups and the
Gaussian and Laguerre unitary matrix ensembles. Another viewpoint of our
generalizations is that they extend to Hankel determinants the Fisher-Hartwig
asymptotic form known for Toeplitz determinants.Comment: 25 page
The FERRUM project: Transition probabilities for forbidden lines in [FeII] and experimental metastable lifetimes
Accurate transition probabilities for forbidden lines are important
diagnostic parameters for low-density astrophysical plasmas. In this paper we
present experimental atomic data for forbidden [FeII] transitions that are
observed as strong features in astrophysical spectra.
Aims: To measure lifetimes for the 3d^6(^3G)4s a ^4G_{11/2} and 3d^6(^3D)4s b
^4D_{1/2} metastable levels in FeII and experimental transition probabilities
for the forbidden transitions 3d^7 a ^4F_{7/2,9/2}- 3d^6(^3G)4s a ^4G_{11/2}.
Methods: The lifetimes were measured at the ion storage ring facility CRYRING
using a laser probing technique. Astrophysical branching fractions were
obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging
Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching
fractions were combined to yield absolute transition probabilities.
Results: The lifetimes of the a ^4G_{11/2} and the b ^4D_{1/2} levels have
been measured and have the following values, 0.75(10) s and 0.54(3) s
respectively. Furthermore, we have determined the transition probabilities for
two forbidden transitions of a ^4F_{7/2,9/2}- a ^4G_{11/2} at 4243.97 and
4346.85 A. Both the lifetimes and the transition probabilities are compared to
calculated values in the literature.Comment: 5 pages, accepted for publication in A&
Random matrix ensembles with an effective extensive external charge
Recent theoretical studies of chaotic scattering have encounted ensembles of
random matrices in which the eigenvalue probability density function contains a
one-body factor with an exponent proportional to the number of eigenvalues. Two
such ensembles have been encounted: an ensemble of unitary matrices specified
by the so-called Poisson kernel, and the Laguerre ensemble of positive definite
matrices. Here we consider various properties of these ensembles. Jack
polynomial theory is used to prove a reproducing property of the Poisson
kernel, and a certain unimodular mapping is used to demonstrate that the
variance of a linear statistic is the same as in the Dyson circular ensemble.
For the Laguerre ensemble, the scaled global density is calculated exactly for
all even values of the parameter , while for (random
matrices with unitary symmetry), the neighbourhood of the smallest eigenvalue
is shown to be in the soft edge universality class.Comment: LaTeX209, 17 page
KPZ equation in one dimension and line ensembles
For suitably discretized versions of the Kardar-Parisi-Zhang equation in one
space dimension exact scaling functions are available, amongst them the
stationary two-point function. We explain one central piece from the technology
through which such results are obtained, namely the method of line ensembles
with purely entropic repulsion.Comment: Proceedings STATPHYS22, Bangalore, 200
Parking and the visual perception of space
Using measured data we demonstrate that there is an amazing correspondence
among the statistical properties of spacings between parked cars and the
distances between birds perching on a power line. We show that this observation
is easily explained by the fact that birds and human use the same mechanism of
distance estimation. We give a simple mathematical model of this phenomenon and
prove its validity using measured data
Live-cell topology assessment of URG7, MRP6âââ and SP-C using glycosylatable green fluorescent protein in mammalian cells.
Experimental tools to determine membrane topology of a protein are rather limited in higher eukaryotic organisms. Here, we report the use of glycosylatable GFP (gGFP) as a sensitive and versatile membranetopology reporter in mammalian cells. gGFP selectively loses its fluorescence upon N-linked glycosylationin the ER lumen. Thus, positive fluorescence signal assigns location of gGFP to the cytosol whereas nofluorescence signal and a glycosylated status of gGFP map the location of gGFP to the ER lumen. By usingmammalian gGFP, the membrane topology of disease-associated membrane proteins, URG7, MRP6102,SP-C(Val) and SP-C(Leu) was confirmed. URG7 is partially targeted to the ER, and inserted in Cinform.MRP6102and SP-C(Leu/Val) are inserted into the membrane in Coutform. A minor population of untarget-ed SP-C is removed by proteasome dependent quality control system
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