8,296 research outputs found
A Model of Strongly Correlated Electrons with Condensed Resonating-Valence-Bond Ground States
We propose a new exactly solvable model of strongly correlated electrons. The
model is based on a - model of the CuO plane with infinitely large
repulsive interactions on Cu-sites, and it contains additional
correlated-hopping, pair-hopping and charge-charge interactions of electrons.
For even numbers of electrons less than or equal to 2/3-filling, we construct
the exact ground states of the model, all of which have the same energy and
each of which is the unique ground state for a fixed electron number. It is
shown that these ground states are the resonating-valence-bond states which are
also regarded as condensed states in which all electrons are in a single
two-electron state. We also show that the ground states exhibit off-diagonal
long-range order.Comment: 17 pages, 1 figure, v2: minor changes, v3: minor changes and typos
correction
Network coding based wireless broadcast with performance guarantee
© 2014 IEEE. Wireless broadcast has been increasingly used to deliver information of common interest to a large number of users. There are two major challenges in wireless broadcast: the unreliable nature of wireless links and the difficulty of acknowledging the correct reception of every broadcast packet by every user when the number of users becomes large. In this paper, by resorting to stochastic geometry analysis, we develop a network coding based broadcast scheme that allows a base station (BS) to broadcast a given number of packets to a large number of users, without user acknowledgment, while being able to provide a performance guarantee on the probability of successful delivery. Further, the BS only has limited statistical information about the environment including the spatial distribution of users (instead of their exact locations and number) and the wireless propagation model. Performance analysis is conducted. On that basis, an upper and a lower bound on the number of packet transmissions required to meet the performance guarantee are obtained. Simulations are conducted to validate the accuracy of the theoretical analysis. The technique and analysis developed in this paper are useful for designing efficient and reliable wireless broadcast strategies
Comparison of Wide and Compact Fourth Order Formulations of the Navier-Stokes Equations
In this study the numerical performances of wide and compact fourth order
formulation of the steady 2-D incompressible Navier-Stokes equations will be
investigated and compared with each other. The benchmark driven cavity flow
problem will be solved using both wide and compact fourth order formulations
and the numerical performances of both formulations will be presented and also
the advantages and disadvantages of both formulations will be discussed
Doping dependence of charge dynamics in electron-doped cuprates
Within the t-t'-J model, the doping dependence of charge dynamics in
electron-doped cuprates is studied. The conductivity spectrum shows a pseudogap
structure with a low-energy peak appearing at and an rather
sharp midinfrared peak appearing around , and the
resistivity exhibits a crossover from the high temperature metallic-like to low
temperature insulating-like behavior in the relatively low doped regime, and a
metallic-like behavior in the relatively high doped regime, in qualitative
agreement with experiments. Our results also show that these unusual behaviors
of the charge dynamics is intriguingly related to the magnetic correlation in
the system.Comment: 5 pages, 3 figures, discussions are added, accepted for publication
in Phys. Lett.
SO(5) structure of p-wave superconductivity for spin-dipole interaction model
A closed SO(5) algebraic structure in the the mean-field form of the
Hamiltonian the pure p-wave superconductivity is found that can help to
diagonalized by making use of the Bogoliubov rotation instead of the
Balian-Werthamer approach. we point out that the eigenstate is nothing but
SO(5)-coherent state with fermionic realization. By applying the approach to
the Hamiltonian with dipole interaction of Leggett the consistency between the
diagonalization and gap equation is proved through the double-time Green
function. The relationship between the s-wave and p-wave superconductivities
turns out to be recognized through Yangian algebra, a new type of
infinite-dimensional algebra.Comment: 7 pages, no figures. Accepted Journal of Physcis A: Mathematical and
Genera
Recent Progress in Neutron Star Theory
This review contains chapters discussing: Energy density fluctionals of
nuclear matter, Many-body theory of nucleon matter, Hadronic and quark matter,
Mixtures of phases in dense matter, Neutron star observations and predictions.Comment: 33 pages +13 figs., Ann. Rev. Nucl. & Part. Science, 200
Network coding based wireless broadcast with performance guarantee
Wireless broadcast has been increasingly used to
deliver information of common interest to a large number of users.
There are two major challenges in wireless broadcast: the unreliable
nature of wireless links and the difficulty of acknowledging
the correct reception of every broadcast packet by every user when
the number of users becomes large. In this paper, by resorting to
stochastic geometry analysis, we develop a network coding based
broadcast scheme that allows a base station (BS) to broadcast
a given number of packets to a large number of users, without
user acknowledgment, while being able to provide a performance
guarantee on the probability of successful delivery. Further, the
BS only has limited statistical information about the environment
including the spatial distribution of users (instead of their exact
locations and number) and the wireless propagation model. Performance
analysis is conducted. On that basis, an upper and a
lower bound on the number of packet transmissions required to
meet the performance guarantee are obtained. Simulations are
conducted to validate the accuracy of the theoretical analysis.
The technique and analysis developed in this paper are useful for
designing efficient and reliable wireless broadcast strategies
VAMPIRE® fundus image analysis algorithms:Validation and diagnostic relevance in hypertensive cats
OBJECTIVES: To validate a retinal imaging software named VAMPIRE® (Vascular Assay and Measurement Platform for Images of the Retina) in feline patients and test the clinical utility in hypertensive cats. ANIMALS STUDIED: One hundred and five healthy cats were enrolled. They represented the normal dataset used in the validation (group 1). Forty-three hypertensive cats with no noticeable retinal abnormalities were enrolled for the clinical validity of the software (group 2). PROCEDURES: Eleven points (4 veins, 4 arteries, and 3 arterial bifurcations) were measured for each digital image. Repeatability and reproducibility of measurements were assessed using two independent operators. Data were statistically analyzed by the Mann-Whiney and Tukey box plot. Significance was considered when P < 0.05. RESULTS: Two hundred and ten retinal images were analyzed for a total of 2310 measurements. Total mean was 9.1 and 6.1 pixels for veins and arteries, respectively. First, second, and third arteriolar bifurcations angles were 73.6°, 76.9°, and 85.4°, respectively. A comparison between groups 1 and 2 showed a statistically significant reduction in arteriolar diameter (mean 3.3 pixels) and branch angle (55°, 47.8° and 59.9°) associated with increasing vein diameter (mean 24.15 pixels). CONCLUSIONS: Current image analysis techniques used in human medicine were investigated in terms of extending their use to veterinary medicine. The VAMPIRE® algorithm proved useful for an objective diagnosis of retinal vasculature changes secondary to systemic hypertension in cats, and could be an additional diagnostic test for feline systemic hypertension
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