3,108 research outputs found
The controversy in the process: potential scattering or resonance ?
The reaction shows a broad peak at 1.5
GeV in the channel which has no counterpart in the
channel. This "resonance" is considered as a candidate for a
state in the "s-channel". We show, however, that it can also
be explained by potential scattering of via the -
exchange in the "t-channel".Comment: 12 pages, latex, 3 postscript figures, to appear in Zeitschrift fur
Physi
Convergence rate of dimension reduction in Bose-Einstein condensates
In this paper, we study dimension reduction of the three-dimensional (3D)
Gross-Pitaevskii equation
(GPE) modelling Bose-Einstein condensation under different limiting
interaction and trapping frequencies parameter regimes.
Convergence rates for the dimension reduction of 3D ground state and dynamics
of the GPE in the case of disk-shaped condensation and cigar-shaped
condensation are reported based on our asymptotic and numerical results. In
addition, the parameter regimes in which the 3D GPE cannot be reduced to lower
dimensions are identified.Comment: 27pages; 9 figure
Evaluation of the stress singularities of plane V-notches in bonded dissimilar materials
According to the linear theory of elasticity, there exists a combination of different orders of stress singularity at a V-notch tip of bonded dissimilar materials. The singularity reflects a strong stress concentration near the sharp V-notches. In this paper, a new way is proposed
in order to determine the orders of singularity for two-dimensional V-notch problems. Firstly, on the basis of an asymptotic stress field in terms of radial coordinates at the V-notch tip, the governing equations of the elastic theory are transformed into an eigenvalue problem of ordinary differential equations (ODEs) with respect to the circumferential coordinate h around the notch tip. Then the interpolating matrix method established by the first author is further developed to solve the general eigenvalue problem. Hence, the singularity orders of the V-notch problem are determined through solving the corresponding
ODEs by means of the interpolating matrix method. Meanwhile, the associated eigenvectors of the displacement and stress fields near the V-notches are also obtained. These functions are essential in calculating the amplitude of the stress field described as generalized stress intensity factors of the V-notches. The present method is also available to deal with the plane V-notch problems in bonded orthotropic multi-material. Finally, numerical
examples are presented to illustrate the accuracy and the effectiveness of the method
LinkMind: Link Optimization in Swarming Mobile Sensor Networks
A swarming mobile sensor network is comprised of a swarm of wirelessly connected mobile robots equipped with various sensors. Such a network can be applied in an uncertain environment for services such as cooperative navigation and exploration, object identification and information gathering. One of the most advantageous properties of the swarming wireless sensor network is that mobile nodes can work cooperatively to organize an ad-hoc network and optimize the network link capacity to maximize the transmission of gathered data from a source to a target. This paper describes a new method of link optimization of swarming mobile sensor networks. The new method is based on combination of the artificial potential force guaranteeing connectivities of the mobile sensor nodes and the max-flow min-cut theorem of graph theory ensuring optimization of the network link capacity. The developed algorithm is demonstrated and evaluated in simulation
Circular Stochastic Fluctuations in SIS Epidemics with Heterogeneous Contacts Among Sub-populations
The conceptual difference between equilibrium and non-equilibrium steady
state (NESS) is well established in physics and chemistry. This distinction,
however, is not widely appreciated in dynamical descriptions of biological
populations in terms of differential equations in which fixed point, steady
state, and equilibrium are all synonymous. We study NESS in a stochastic SIS
(susceptible-infectious-susceptible) system with heterogeneous individuals in
their contact behavior represented in terms of subgroups. In the infinite
population limit, the stochastic dynamics yields a system of deterministic
evolution equations for population densities; and for very large but finite
system a diffusion process is obtained. We report the emergence of a circular
dynamics in the diffusion process, with an intrinsic frequency, near the
endemic steady state. The endemic steady state is represented by a stable node
in the deterministic dynamics; As a NESS phenomenon, the circular motion is
caused by the intrinsic heterogeneity within the subgroups, leading to a broken
symmetry and time irreversibility.Comment: 29 pages, 5 figure
PP-wave String Interactions from String Bit Model
We construct the string states ,
and in the Hilbert space of the quantum
mechanical orbifold model so as to calculate the three point functions and the
matrix elements of the light-cone Hamiltonian from the interacting string bit
model. With these string states we show that the three point functions and the
matrix elements of the Hamiltonian derived from the interacting string bit
model up to order precisely match with those computed from the
perturbative SYM theory in BMN limit.Comment: 20 pages, no figure, LaTeX, some changes made and references adde
An adolescent with both Wegener's Granulomatosis and chronic blastomycosis
We report a case of Wegener's Granulomatosis (WG) associated with blastomycosis. This appears to be the first case report of WG co-existing with a tissue proven blastomycosis infection. The temporal correlation of the two conditions suggests that blastomycosis infection (and therefore possibly other fungal infections), may trigger the systemic granulomatous vasculitis in a predisposed individual; a provocative supposition warranting further study
Numerical Investigation of the Performance of Three Hinge Designs of Bileaflet Mechanical Heart Valves
Thromboembolic complications (TECs) of bileaflet mechanical heart valves (BMHVs) are believed to be due to the nonphysiologic mechanical stresses imposed on blood elements by the hinge flows. Relating hinge flow features to design features is, therefore, essential to ultimately design BMHVs with lower TEC rates. This study aims at simulating the pulsatile three-dimensional hinge flows of three BMHVs and estimating the TEC potential associated with each hinge design. Hinge geometries are constructed from micro-computed tomography scans of BMHVs. Simulations are conducted using a Cartesian sharp-interface immersed-boundary methodology combined with a second-order accurate fractional-step method. Leaflet motion and flow boundary conditions are extracted from fluid–structure-interaction simulations of BMHV bulk flow. The numerical results are analyzed using a particle-tracking approach coupled with existing blood damage models. The gap width and, more importantly, the shape of the recess and leaflet are found to impact the flow distribution and TEC potential. Smooth, streamlined surfaces appear to be more favorable than sharp corners or sudden shape transitions. The developed framework will enable pragmatic and cost-efficient preclinical evaluation of BMHV prototypes prior to valve manufacturing. Application to a wide range of hinges with varying design parameters will eventually help in determining the optimal hinge design
Two-Fermion Bound States within the Bethe-Salpeter Approach
To solve the spinor-spinor Bethe-Salpeter equation in Euclidean space we
propose a novel method related to the use of hyperspherical harmonics. We
suggest an appropriate extension to form a new basis of spin-angular harmonics
that is suitable for a representation of the vertex functions. We present a
numerical algorithm to solve the Bethe-Salpeter equation and investigate in
detail the properties of the solution for the scalar, pseudoscalar and vector
meson exchange kernels including the stability of bound states. We also compare
our results to the non relativistic ones and to the results given by light
front dynamics.Comment: 32 pages, XIII Tables, 8 figure
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