Bound Pair Research Articles

Stable bound pair of spiral waves in rabbit ventricles.

Journal of Cardiovascular ElectrophysiologyVolume 13, Issue 4 p. 414-414 Stable Bound Pair of Spiral Waves in Rabbit Ventricles TSU-JUEY WU M.D., TSU-JUEY WU M.D. *Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, TaiwanSearch for more papers by this authorMARK-ANTHONY BRAY M.S.E., MARK-ANTHONY BRAY M.S.E. †Department of Biomedical Engineering, Vanderbilt University, Nashville, TennesseeSearch for more papers by this authorCHIH-TAI TING M.D., Ph.D., CHIH-TAI TING M.D., Ph.D. *Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, TaiwanSearch for more papers by this authorSHIEN-FONG LIN Ph.D., SHIEN-FONG LIN Ph.D. ‡Department of Physics and Astronomy, Vanderbilt University, Nashville, TennesseeSearch for more papers by this author TSU-JUEY WU M.D., TSU-JUEY WU M.D. *Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, TaiwanSearch for more papers by this authorMARK-ANTHONY BRAY M.S.E., MARK-ANTHONY BRAY M.S.E. †Department of Biomedical Engineering, Vanderbilt University, Nashville, TennesseeSearch for more papers by this authorCHIH-TAI TING M.D., Ph.D., CHIH-TAI TING M.D., Ph.D. *Division of Cardiology, Department of Medicine, Taichung Veterans General Hospital and Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, TaiwanSearch for more papers by this authorSHIEN-FONG LIN Ph.D., SHIEN-FONG LIN Ph.D. ‡Department of Physics and Astronomy, Vanderbilt University, Nashville, TennesseeSearch for more papers by this author First published: 12 August 2003 https://doi.org/10.1046/j.1540-8167.2002.00414.xCitations: 10 Address for correspondence: Shien-Fong Lin, Ph.D., Beverly Module #135, Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Los Angeles, CA 90048. Fax: 310-423-0305; E-mail: [email protected] This study was supported by National Institutes of Health Grants R01-HL58533 and R01-HL58241, and the Yen Tjing Ling Medical Foundation (CI-89-7-3), Taipei, Taiwan. A phase movie and a wavefront movie of double spiral can be viewed at http://www.vanderbilt.edu/lsp/fluorimg.htm J Cardiovasc Electrophysiol, Vol. 13, p. 414, April 2002. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume13, Issue4April 2002Pages 414-414 RelatedInformation

Dark solitons in a two-component Bose-Einstein condensate.

The creation and interaction of dark solitons in a two-component Bose-Einstein condensate is investigated. For a miscible case, the interaction of dark solitons in different components is studied. Various possible scenarios are presented, including the formation of a soliton-soliton bound pair. We also analyze the soliton propagation in the presence of domains, and show that a dark soliton can be transferred from one component to the other at the domain wall when it exceeds a critical velocity. For lower velocities multiple reflections within the domain are observed, where the soliton is evaporated and accelerated after each reflection until it finally escapes from the domain.

Excited-state reversible geminate reaction. I. Two different lifetimes

We obtain an accurate long-time solution for the diffusive kinetics of an excited geminate pair dissociating reversibly in solution, where the excited-state lifetimes of the bound and unbound states may be nonequal. We analyze the long-time asymptotic behavior, finding a transition between two types of behaviors. In region A, the excited bound pair decays as t−3/2 exp(−t/τ0′), where τ0′ is the lifetime of the unbound state. In region AB, the decay is a pure exponential. At the critical value of the parameters where the transition occurs, we find a t−1/2 exp(−t/τ0′) decay. These predictions are tested against an exact numerical solution of the corresponding coupled partial differential equations. For region A, we supply an experimental example involving time-resolved excited-state proton transfer from 5-cyano-2-naphthol to dimethyl sulfoxide.

Effective potential for fermion pairs in non-relativistic Maxwell-Chern-Simons-matter theory

In Maxwell-Chern-Simons-matter theory, there is the possibility that two equal-charged fermions can form a bound state pair. We consider the theory in the nonrelativistic limit and obtain the effective potential for the fermion pairs. It is shown that the weak coupling is essential for the condensation of fermion pairs.

Generalization of the Berezinskii-Kosterlitz-Thouless theory to higher vortex densities

The Berezinskii-Kosterlitz-Thouless theory for superfluid films is generalized in a straightforward way that (a) corrects for overlapping vortex-antivortex pairs at high pair density and (b) utilizes a dielectric approximation for the polarization of the vortex system and a local field correction. Generalized Kosterlitz equations are derived, containing higher order terms, which are compared with earlier predictions. These terms cause the total pair density to remain finite for temperatures above the transition so that it is not necessary to introduce an ad hoc cut-off, as opposed to the original Berezinskii-Kosterlitz-Thouless theory. The low-temperature bound pair phase is destabilized for small vortex core energy. The behaviour of the stiffness constant and of the correlation length close to the transition is not affected by the higher order terms. A first-order transition as suggested by other authors is not found for any values of the parameters. The pair density is calculated for temperatures below and above the transition. Possible experiments and the applicability of the extended approach are discussed. The approach is found to be applicable even in a significant temperature range above the transition.

Conservation of channel spin in transfer reactions

The conservation of channel spin implying that the spin of the initial bound pair coupled to that of the initial free particle should result in the same channel spin as the spin of the final bound pair coupled to the spin of the final free particle, follows as a consequence of three-body theory of transfer reactions with the assumption of separability of two-bodyt-matrix. To test the validity of this principle we look at the experimental data on stripping reactions on even-even nuclei. We find that although reactions to channels not conforming to channel spin conservation are not altogether ruled out, the cross-sections of reactions violating channel spin conservation are much smaller than those conforming to channel spin conservation.

Dissociation of Flux Line in Unconventional Superconductor

Besides usual flux lines the topology of the “real” vector phase in a multicomponent superconductor admits an existence of half-quantum vortices in the bulk. These vortices have a divergent energy near H c 1 . However, the possibility of their existence reveals itself in an instability of a usual singular one-quantum vortex towards dissociation into the nonsingular bound pair of half-quantum vortices. Considering an example of the multicomponent Ginzburg-Landau functional we found analytically critical values of phenomenological parameters corresponding to this instability, as well as the symmetry group of the vortex pair.

Low energy description of fermion pairs in topologically massive QED 2+1 with N flavours

In topologically massive QED 2+1 with N flavours, there is the possibility that two equal-charged fermions can form a bound state pair in either s-wave or p-wave. We are concerned with the s-wave pairs and obtain the low energy effective action describing them. It is shown that the fermion pairs behave like doubly charged spin 1 bosons and, when they condense, the gauge field acquires the longitudinal mass. The approximate SU ( 2) symmetry due to the similarity between the fermion pairs and the gauge field is discussed.

Chaotic capture of vortices by a moving body. II. Bound pair model.

Previously, we have presented a simple model for the interaction of a fluid vortex structure with a moving bluff body, and demonstrated the existence of a trapping mechanism related to chaotic scattering. This single point vortex model required explicit perturbation to generate chaos and the subsequent complex dynamics. Here, we present a model which attempts to introduce internal degrees-of-freedom in the vortex structure in the simplest manner, by replacing the single vortex with a like-signed pair. We show that this model exhibits chaotic trapping without the need of explicit perturbation, however, the region of parameter space for which trapping occurs is exceedingly small due to the spatially dependent form of the perturbation. We claim that this result explains some the behavior observed in Navier-Stokes simulations of the same vortex-body system, where we find close correspondence between the dynamics of an extended vorticity distribution and the single vortex model. Finally, we generalize the model to unequal strength vortex pairs, and find more complex behavior which includes "partial" capture of the weaker vortex by the body. (c) 1994 American Institute of Physics.

Composite bosons and quantum coherent effects in the negative-U Hubbard model

A real-time functional integral approach at finite temperature is used for self-consistent formulation of the dynamics and superconducting phase transition of pre-formed composite bosons in the extended negative— U Hubbard model in the large U limit. By employing the representation in terms of the amplitude and phase of the bound pair field we derive the effective phase Hamiltonian and exploit the effects associated with coherent bound pair tunneling at the microscopic level - responsible for the phase coherent state, as well as the dissipative effects due to quasiparticle charge transfer. Striking formal similarity of the physical picture in the large— U limit to those modeled by Josephson-coupled arrays with charging effects is pointed out.

Bound pair states in nuclear matter

The self-consistency between a Brueckner like ladder equation for the effective interaction which treats particles and holes symmetrically and the Dyson equation is discussed. A study of pairing instabilities in nuclear matter for realistic nucleon-nucleon interactions is presented. Bound pair states in nuclear matter are obtained and their contribution to the interaction is compared to the continuum contribution using dispersion relations. A survey of simple pairing properties for the Reid potential is made. It is suggested that the actual ground state of nuclear matter around the empirical saturation density corresponds to a superfluid with pairing occurring with deuteron quantum numbers.

Pairing correlations: II. Exact model ground-state results for generalised ladders

In this series of papers, the so-called ground-state version of the [exp(S) or] coupled-cluster formalism (CCF) of quantum many-body theory is applied to the general problem of pairing correlations within a many-body system of identical fermions. In this second work in the series we restrict ourselves to exact calculations and concentrate on analytic solutions to the generalised ladder approximations formulated in the first paper. We focus attention on the particular model case of a general (non-local) separable potential, and work within the so-called complete ladder (CLAD) approximation which was shown in the earlier paper to be the CCF formulation of the well-known Galitskii approximation. We show how the CLAD approximation reduces in this case to a highly non-trivial pair of coupled nonlinear integral equations for the four-point correlation function,S 2, which provides a measure of the two-particle/two-hole component in the true “ground-state” wave-function. In the further derivation of exact analytic solutions for bothS 2 and the corresponding “ground-state” energy, we also see how various types of composite pairs within the many-body medium manifest themselves as “virtual (de-)excitations”. We thus show how our CCF provides an efficient and unified framework in which to describe all aspects of pairing, such as: (i) a possible free bound pair and its gradual approach to “dissolution” as the density is increased; (ii) the possible appearance of a second bound pair of predominantly hole-like quasi-particles above some lower critical density (which depends on the total momentum of the pair); (iii) the unstable but bound resonant pairs that can exist for densities above a comparable upper critical density at which the two previous types of real bound pairs have “dissolved”; and (iv) Cooper pairs. Even though each of these composite pairs leads to a new “condensed-pair phase” of lower energy, we further show that our so-called ground-state CCF leads only to the fluid-like state of uncondensed particles. In a third paper in this series we use the solutions obtained here as input to the analogous excited-state version of the CCF, and show how these various composite pairs materialise as “negative energy (de-)excitations”.

Internal friction and strain aging of ferrous austenite

The effects of quenching, cold work, and electron irradiation on Snoek-like (bound pair) carbon internal friction peaks in some Fe-base austenitic alloys have been examined and correlated with previous studies of dynamic strain aging and self diffusion in similar materials. The results imply that i) the bound pair peaks have their origin in the stress-induced reorientation of carbon-vacancy complexes, ii) the binding energy of these complexes is large and possibly precludes the occurrence of cold-work-type peaks observed in bcc materials, and iii) the carbon-vacancy interaction controls many aspects of strain-aging and self diffusion in austenites which contain carbon.

Intrinsic and extrinsic defect pairs in caesium halides

Interaction energies of cation-anion vacancy pairs and divalent cation impurity-vacancy pairs in caesium halides have been evaluated by means of ionic lattice calculations with a rigorous treatment of the relaxations of ions in the vicinity of the defects. The binding energy of the first associated vacancy pair is lower than the Coulombic value, while that of the second associated pair is close to the Coulombic value. The binding energies of the divalent cation impurity-vacancy pairs vary in the order, third > fourth > second > first associated state, the energy of the second bound pair being close to the Coulombic value.