35,449 research outputs found
A new convolution theorem associated with the linear canonical transform
In this paper, we first introduce a new notion of canonical convolution
operator, and show that it satisfies the commutative, associative, and
distributive properties, which may be quite useful in signal processing.
Moreover, it is proved that the generalized convolution theorem and generalized
Young's inequality are also hold for the new canonical convolution operator
associated with the LCT. Finally, we investigate the sufficient and necessary
conditions for solving a class of convolution equations associated with the
LCT.Comment: 13 page
M-Theory Brane as Giant Graviton and the Fractional Quantum Hall Effect
A small number of M-theory branes as giant gravitons in the M-theory sector
of LLM geometry is studied as a probe. The abelian way shows that the low
energy effective action for M-theory brane is exactly the 2d electron subject
to a vertical magnetic field. We also briefly discuss the microscopic
description of M2-brane giant graviton in this geometry, in the language of a
combination of D0-branes as fuzzy 2-spheres. Then we go to the well-established
Noncommutative Chern-Simons theory description. After quantization, well
behaved Fractional Quantum Hall Effect is demonstrated. This goes beyond the
original LLM description and should be some indication of novel geometry.Comment: 20 pages, uses JHEP3.cl
Bidirectional and passive optical field to microwave field quantum converter with high bandwidth
The conversion between microwave photons and optical photons with quantum
coherence is important for quantum communication and computation. In this
paper, we report a proposal using an ensemble of atoms coupled to microwave and
optical resonators. Input photons to one resonator are converted into output
photons in the other resonator without active operation. Usually the conversion
is only optimized at certain frequency. In our proposal, we find that the
efficiency is almost a constant and can be close to 100% in a large interval of
frequency, i.e. a high-bandwidth conversion can be realized with our proposal.Comment: 6 pages, 4 figure
Effective Field Theory of Integrating out Sfermions in the MSSM: Complete One-Loop Analysis
We apply the covariant derivative expansion of the Coleman-Weinberg potential
to the sfermion sector in the minimal supersymmetric standard model, matching
it to the relevant dimension-6 operators in the standard model effective field
theory at one-loop level. Emphasis is paid to nondegenerate large soft
supersymmetry breaking mass squares, and the most general analytical Wilson
coefficients are obtained for all pure bosonic dimension-6 operators. In
addition to the non-logarithmic contributions, they generally have another
logarithmic contributions. Various numerical results are shown, in particular
the constraints in the large branch reproducing the ~GeV Higgs mass
can be pushed to high values to almost completely probe the low stop mass
region at the future FCC-ee experiment, even given the Higgs mass calculation
uncertainty.Comment: Correction of Wilson coefficients to match 1512.03003, numerically
constraints almost unchanged, published versio
A mathematical model about human infections of H7N9 influenza in China with the intervention of live poultry markets closing
This paper develops a deterministic differential equations model that
captures the H7N9 virus transmission from live poultry to human via
poultry-human contacts in live poultry markets (LPMs). The virus circulation
among live poultry, which happens but is hard to be detected (since
contaminated live poultry appear to be asymptomatic), is also incorporated in
the model. The time-dependent contact rate between human and live poultry based
on LPMs closing information can be estimated. From data of LPMs closing news,
the contact rate function can be easily estimated. This model could serve as a
rational basis for public health authorities to evaluate the effectiveness of
LPM closing, as well as other interventions according to simple modifications.
Without data about daily cases, I also provide suggestions for some of the
basic parameters that would be a useful fitness parameter set for future
simulation
estimates for the Bergman projection on some Reinhardt domains
We obtain regularity for the Bergman projection on some Reinhardt
domains. We start with a bounded initial domain with some symmetry
properties and generate successor domains in higher {dimensions}. We prove: If
the Bergman kernel on satisfies appropriate estimates, then the
Bergman projection on the successor is bounded. For example, the Bergman
projection on successors of strictly pseudoconvex initial domains is bounded on
for . The successor domains need not have smooth boundary nor
be strictly pseudoconvex.Comment: 12 pages, accepted for publication in Proceedings of AM
Refracting into Ultra Diffuse Galaxy NGC 1052-DF2 by Passing near the Center of NGC 1052
The recent observation of the ultra-diffuse galaxy NGC 1052-DF2 shows a
galaxy may lack dark matter. Usually dark matter is much more abundant than
stellar in galaxy environment. This dark matter to baryon mass ratio is
generally larger than the cosmological ratio of about five, since a significant
part of baryon is diffused in the form of intergalactic medium. How to achieve
such a low dark matter to baryon mass ratio is a challenge to the standard
galaxy formation mechanism. Here we show that such a low ratio can be a natural
consequence if the NGC 1052-DF2 had experienced a single passage within a few
kpcs to the center of galaxy NGC 1052. The tidal effect of NGC 1052 in the
encounter will heat the NGC 1052-DF2 up, stretch the previous dwarf galaxy
significantly into its current size. The relative lacking of dark matter in the
observed region is a natural consequence of the dark matter extended
distribution and relatively less concentration in the corresponding central
region before encounter, together with a systematic underestimation of the
trace mass estimator method during relaxation after encounter. The observed
flat distribution of the ultra-diffuse galaxy can be reproduced. Our results
shows no need of introducing any new physical mechanism.Comment: 6 pages, 4 figure
The Bergman Kernel on some Hartogs domains
We obtain new explicit formulas for the Bergman kernel function on two
families of Hartogs domains. To do so, we first compute the Bergman kernels on
the slices of these Hartogs domains with some coordinates fixed, evaluate these
kernel functions at certain points off the diagonal, and then apply a first
order differential operator to them. We find, for example, explicit formulas
for the kernel function on and on We use our
formulas to determine the boundary behavior of the kernel function of these
domains on the diagonal.Comment: 24 pages, accepted for publication in The Journal of Geometric
Analysi
Modeling of Contact Tracing in Epidemic Populations Structured by Disease Age
We consider an age-structured epidemic model with two basic public health
interventions: (i) identifying and isolating symptomatic cases, and (ii)
tracing and quarantine of the contacts of identified infectives. The dynamics
of the infected population are modeled by a nonlinear infection-age-dependent
partial differential equation, which is coupled with an ordinary differential
equation that describes the dynamics of the susceptible population. Theoretical
results about global existence and uniqueness of positive solutions are proved.
We also present two practical applications of our model: (1) we assess public
health guidelines about emergency preparedness and response in the event of a
smallpox bioterrorist attack; (2) we simulate the 2003 SARS outbreak in Taiwan
and estimate the number of cases avoided by contact tracing. Our model can be
applied as a rational basis for decision makers to guide interventions and
deploy public health resources in future epidemics
Time irreversibility in the quantum systems with infinite number of particles
The time irreversible evolution of quantum systems with infinite number of
particles (QSINP) was studied within a newly constructed algebraic framework.
The QSINP could be described by the quantum infinite lattice field. The
*-Algebra R is the set of all dynamic variables of the QSINP, in which a
special addition and multiplication operations were defined. The full pure
state vector (FPSV) \rho, the pure state vector {\rho_f} and the equivalent
relations within them are also well defined. The set of all pure state vectors,
which are equivalent to the FPSV \rho, is a Hilbert Space {H_\rho}, if the
addition, the inner product and the norm were defined in it. The set of all
linear transformation {N_\rho} on {H_\rho} is isomorphic to R, and
{{N_\rho},{H_\rho}} is the representation of R, associated with \rho. The
*-Algebra R has infinitely many non-equivalent irreducible GNS constructions
(representations), associated with different nonequivalent FPSVs respectively.
It is proved that, the dynamical motions of the QSINP is totally within the
GNS construction associated with the initial pure state vector; However, the
time reversal transformation makes the initial FPSV and its corresponding
dynamical evolution into another non-equivalent GNS construction. Therefore,
within the GNS construction associated with the FPSV, the dynamics of the QSINP
is time irreversible.
Finally, due to the Liouville operator has real continuous spectrum within
the GNS construction, the longtime asymptotic solution of Liouville equation in
the GNS construction could be treated by the formal scattering theory. The
Master equation with dissipative term was obtained, which is formally
irrelevant of the initial state and the corresponding GNS construction. This
master equation could be regarded as the evolution equation of the QSINP on R
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