435,620 research outputs found
The Large-scale ISM of SS433/W50 Revisited
With new high-resolution CO and HI data, we revisited the large-scale
interstellar medium (ISM) environment toward the SS 433/W50 system. We find
that two interesting molecular cloud (MC) concentrations, G39.315-1.155 and
G40.331-4.302, are well aligned along the precession cone of SS 433 within a
smaller opening angle of ~7deg. The kinematic features of the two MCs at
~73--84 km/s, as well as those of the corresponding atomic-gas counterparts,
are consistent with the kinematic characteristics of SS 433. That is, the
receding gas from SS 433 jet is probably responsible for the redshifted feature
of G39.315-1.155 near the Galactic plane and the approaching one may power the
blueshifted gas of G40.331-4.302 toward the observer. Moreover, the HI emission
at VLSR~70--90 km/s displays the morphological resemblance with the radio
nebula W50. We suggest that the VLSR=77\pm5 km/s gas is physically associated
with SS 433/W50, leading to a near kinematic distance of 4.9\pm0.4 kpc for the
system. The observed gas features, which are located outside the current radio
boundaries of W50, are probably the fossil record of jet-ISM interactions at
~10^5 years ago. The energetic jets of the unique microquasar have profound
effects on its ISM environment, which may facilitate the formation of molecular
gas on the timescale of <0.1 Myr for the ram pressure of ~2x10^6 K cm-3.Comment: 1 table, 13 figures, to appear in the ApJ. Comments welcom
Full quantum treatment of Rabi oscillation driven by a pulse train and its application in ion-trap quantum computation
Rabi oscillation of a two-level system driven by a pulse train is a basic
process involved in quantum computation. We present a full quantum treatment of
this process and show that the population inversion of this process collapses
exponentially, has no revival phenomenon, and has a dual-pulse structure in
every period. As an application, we investigate the properties of this process
in ion-trap quantum computation. We find that in the Cirac--Zoller computation
scheme, when the wavelength of the driving field is of the order m,
the lower bound of failure probability is of the order after about
controlled-NOT gates. This value is approximately equal to the
generally-accepted threshold in fault-tolerant quantum computation.Comment: 22 pages, 5 figur
Universal Correlation between Critical Temperature of Superconductivity and band structure features
The critical temperature () of superconductors varies a lot.
The factors governing the may hold key clues to understand the
nature of the superconductivity. Thereby, -involved correlations,
such as Matthias laws, Uemura law, and cuprates doping phase diagrams, have
been of great concern. However, the electronic interaction being responsible
for the carriers pairing in high- superconductors is still not
clear, which calls for more comprehensive analyses of the experimental data in
history. In this work, we propose a novel perspective for searching material
gene parameters and -involved correlations. By exploring holistic
band structure features of diverse superconductors, we found a universal
correlation between the maxima and the electron energy levels
for all kinds of superconducting materials. It suggests that the
maxima are determined by the energy level of secondary-outer orbitals, rather
than the band structure nearby the Fermi level. The energy level of
secondary-outer orbitals is a parameter corresponding to the ratio of atomic
orbital hybridization, implying that the fluctuation of the orbital
hybridization is another candidate of pairing glue
Perturbed Hankel determinant, correlation functions and Painlev\'e equations
We continue with the study of the Hankel determinant, generated by a Pollaczek-Jacobi type weight, This reduces to the "pure"
Jacobi weight at We may take , in the situation
while is strictly greater than It was shown in Chen and Dai (2010),
that the logarithmic derivative of this Hankel determinant satisfies a
Jimbo-Miwa-Okamoto -form of Painlev\'e
\uppercase\expandafter{\romannumeral5} ({\rm
P_{\uppercase\expandafter{\romannumeral5}}}). In fact the logarithmic of the
Hankel determinant has an integral representation in terms of a particular
{\rm P_{\uppercase\expandafter{\romannumeral5}}}. \\ In this paper, we show
that, under a double scaling, where the dimension of the Hankel matrix
tends to , and tends to such that is finite,
the double scaled Hankel determinant (effectively an operator determinant) has
an integral representation in terms of a particular {\rm
P_{\uppercase\expandafter{\romannumeral3}'}}. Expansions of the scaled Hankel
determinant for small and large are found. A further double scaling with
where and tends to
such that is finite. In this situation the scaled Hankel determinant
has an integral representation in terms of a particular {\rm
P_{\uppercase\expandafter{\romannumeral5}}}, %which can be degenerate to a
particular {\rm P_{\uppercase\expandafter{\romannumeral3}}} and its small and
large asymptotic expansions are also found
Inverse Problem of Electro-seismic Conversion
When a porous rock is saturated with an electrolyte, electrical fields are
coupled with seismic waves via the electro-seismic conversion. Pride derived
the governing models, in which Maxwell equations are coupled with Biot
equations through the electro-kinetic mobility parameter. The inverse problem
of the linearized electro-seismic conversion consists in two step, namely the
inversion of Biot equations and the inversion of Maxwell equations. We analyze
the reconstruction of conductivity and electro-kinetic mobility parameter in
Maxwell equations with internal measurements, while the internal measurements
are provided by the results of the inversion of Biot equations. We show that
knowledge of two internal data based on well-chosen boundary conditions
uniquely determine these two parameters. Moreover, a Lipschitz type stability
is proved based on the same sets of well-chosen boundary conditions
Critical edge behavior in the perturbed Laguerre ensemble and the Painleve V transcendent
In this paper, we consider the perturbed Laguerre unitary ensemble described
by the weight function of with The Deift-Zhou nonlinear
steepest descent approach is used to analyze the limit of the eigenvalue
correlation kernel. It was found that under the double scaling such that is positive and finite, at the hard edge, the
limiting kernel can be described by the -function related to a
third-order nonlinear differential equation, which is equivalent to a
particular Painlev\'e V (shorted as P) transcendent via a simple
transformation. Moreover, this P transcendent is equivalent to a
general Painlev\'e P transcendent. For large the P
kernel reduces to the Bessel kernel For small
the P kernel reduces to another Bessel kernel
At the soft edge, the limiting kernel is the Airy kernel
as the classical Laguerre weight.Comment: 53 page
Revisiting Street-to-Aerial View Image Geo-localization and Orientation Estimation
Street-to-aerial image geo-localization, which matches a query street-view
image to the GPS-tagged aerial images in a reference set, has attracted
increasing attention recently. In this paper, we revisit this problem and point
out the ignored issue about image alignment information. We show that the
performance of a simple Siamese network is highly dependent on the alignment
setting and the comparison of previous works can be unfair if they have
different assumptions. Instead of focusing on the feature extraction under the
alignment assumption, we show that improvements in metric learning techniques
significantly boost the performance regardless of the alignment. Without
leveraging the alignment information, our pipeline outperforms previous works
on both panorama and cropped datasets. Furthermore, we conduct visualization to
help understand the learned model and the effect of alignment information using
Grad-CAM. With our discovery on the approximate rotation-invariant activation
maps, we propose a novel method to estimate the orientation/alignment between a
pair of cross-view images with unknown alignment information. It achieves
state-of-the-art results on the CVUSA dataset.Comment: WACV 202
Multi-modal Aggregation for Video Classification
In this paper, we present a solution to Large-Scale Video Classification
Challenge (LSVC2017) [1] that ranked the 1st place. We focused on a variety of
modalities that cover visual, motion and audio. Also, we visualized the
aggregation process to better understand how each modality takes effect. Among
the extracted modalities, we found Temporal-Spatial features calculated by 3D
convolution quite promising that greatly improved the performance. We attained
the official metric mAP 0.8741 on the testing set with the ensemble model
Towards Randomized Testing of -Monomials in Multivariate Polynomials
Given any fixed integer , a -monomial is of the format
such that , . -monomials are natural generalizations of
multilinear monomials. Recent research on testing multilinear monomials and
-monomails for prime in multivariate polynomials relies on the property
that is a field when is prime. When is not prime, it
remains open whether the problem of testing -monomials can be solved in some
compatible complexity. In this paper, we present a randomized
algorithm for testing -monomials of degree that are found in a
multivariate polynomial that is represented by a tree-like circuit with a
polynomial size, thus giving a positive, affirming answer to the above
question. Our algorithm works regardless of the primality of and improves
upon the time complexity of the previously known algorithm for testing
-monomials for prime .Comment: 21 pages, 5 figures. arXiv admin note: text overlap with
arXiv:1007.2675, arXiv:1007.2678, arXiv:1007.2673 by other author
Single-use MIMO system, Painlev\'e transcendents and double scaling
In this paper we study a particular Painlev\'e V (denoted ) that
arises from Multi-Input-Multi-Output (MIMO) wireless communication systems.
Such a appears through its intimate relation with the Hankel determinant
that describes the moment generating function (MGF) of the Shannon capacity.
This originates through the multiplication of the Laguerre weight or the Gamma
density for by
with a scaling parameter. Here the
parameter "generates" the Shannon capacity, see Yang Chen and Matthew McKay,
IEEE Trans. IT, 58 (2012) 4594--4634. It was found that the MGF has an integral
representation as a functional of and , where satisfies
the "classical form" of . In this paper, we consider the situation where
the number of transmit antennas, (or the size of the random matrix), tends
to infinity, and the signal-to-noise ratio (SNR) tends to infinity, such
that is finite. Under such double scaling the MGF, effectively
an infinite determinant, has an integral representation in terms of a "lesser"
. We also consider the situations where and linking
the relevant quantity to a solution of the two dimensional sine-Gordon equation
in radial coordinates and a certain discrete Painlev\'e-II. From the large
asymptotic of the orthogonal polynomials, that appears naturally, we obtain the
double scaled MGF for small and large , together with the constant term in
the large expansion. With the aid of these, we derive a number of cumulants
and find that the capacity distribution function is non-Gaussian.Comment: 30 page
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