Role Of Pairs Research Articles

Role of the electron-phonon interaction in the strongly correlated cuprate superconductors

Abstract Using high-resolution angle-resolved photoemission data in conjunction with that from neutron and other probes, we show that electron-phonon coupling is strong in cuprate superconductors and that it plays an important role in pairing. In addition to the strong electron correlation, the inclusion of phonons provides a theoretical framework explaining many important phenomena that cannot be understood by a strongly correlated electronic model alone. In particular, it is indispensable to explain the difference among materials. The phonons with the wavenumber around the (0, qy ) and (qx , 0) axes create d-wave pairing while that near (π, π) are pair breaking. Therefore the half-breathing mode of the oxygen motions helps d-wave superconductivity.

Role of the electron-phonon interaction in the strongly correlated cuprate superconductors

Using high resolution angle-resolved photoemission data in conjunction with that from neutron and other probes, we show that electron-phonon (el-ph) coupling is strong in cuprates superconductors and it plays an important role in pairing. In addition to the strong electron correlation, the inclusion of phonons provides a theoretical framework explaining many important phenomena that cannot be understood by a strongly correlated electronic model alone. Especially it is indispensable to explain the difference among materials. The phonons with the wave number around the (0,qx) and (qx,0) axes create the d-wave pairing while that near (pi,pi) are pair breaking. Therefore the half-breathing mode of the oxygen motions helps d-wave superconductivity.

Hanging on to your homolog: the roles of pairing, synapsis and recombination in the maintenance of homolog adhesion.

Homologous chromosomes initially undergo weak alignments that bring homologous sequences into register during meiosis. These alignments can be facilitated by two types of mechanisms: interstitial homology searches and telomere-telomere alignments. As prophase (and chromatin compaction) proceeds, these initial pairings or alignments need to be stabilized. In at least some organisms, such as Saccharomyces cerevisiae and S. pombe, these pairings can apparently be maintained by the creation of recombination intermediates. In contrast, synapsis during zygotene may be able to facilitate and/or maintain chromosome pairing even in the absence of exchange in several higher organisms. It thus seems possible that the synaptonemal complex plays a role both in maintaining homolog adhesion during meiotic prophase and, more speculatively, in facilitating meiotic exchange.

Phonon density of states and superconductivity in Nd1.85Ce0.15CuO4.

Inelastic-neutron-scattering techniques have been used to measure the generalized phonon density of states in superconducting ${\mathrm{Nd}}_{1.85}$${\mathrm{Ce}}_{0.15}$${\mathrm{CuO}}_{4}$. There is reasonable agreement at low energies between our measurements and recent point-contact-tunneling density-of-states measurements reported by Huang et al., which suggests that phonons play a major role in pairing in the electron-superconductor systems. The correspondence at higher energies, however, is not particularly good, but probably reflects the difficulty in obtaining quantitative tunneling data.

Effect of interlayer coupling on superconducting properties: Application to sound attenuation

Interlayer coupling is one of the important issues in understanding transport properties in the normal and superconducting state of the cuprates. Its implications for the superconducting state, such as its role in pairing in the c-direction. are not well understood. New results are presented for longitudinal acoustic attenuation iit a layered/anisotropic superconductor. The calculation focuses on the role of anisotropy in the band structure and in the superconducting order parameter. Measurements of acoustic attenuation are useful as they can provide information on the dielectric response of the charge carriers in the low wavevector q and frequency ω regime.

Hypervariable minisatellite regions are sites for crossing-over at meiosis in man.

In situ hybridization to human meiotic metaphase I (MI) preparations, using the labeled minisatellite core sequence lambda 33.15, showed clustering of autoradiographic grains principally at or around chiasmata, autosomal sites where crossing-over had occurred. For the XY bivalent, the pairing region formed between the terminal regions of the two short arms (Xpter Ypter), was also a principal site of labeling; in addition, the terminal region of the X long arm (Xqter) was labeled. Control experiments using a member of the human Alu family of dispersed repeated DNA sequences showed a much more randomized grain distribution, with clustering over chiasmata being far less obvious. The data provide support for the suggestion that polymorphic minisatellite regions within the human genome might play a significant role in pairing and/or recombination.

Ne20(α,2α)O16reaction at 78.6 MeV

The $^{20}\mathrm{Ne}(\ensuremath{\alpha},2\ensuremath{\alpha})^{16}\mathrm{O}$ reaction has been measured at symmetric and asymmetric sets of angles at ${E}_{\ensuremath{\alpha}}=78.6$ MeV. The data indicate that quasifree $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ scattering and, consequently, $\ensuremath{\alpha}$ clustering plays a dominant role for pairs of angles favoring quasifree scattering. The data have been compared with the plane-wave impulse approximation using a radial cutoff. This calculation does not give a good fit to data for non-quasifree angles. The reaction goes predominantly to the $^{16}\mathrm{O}$ ground state with a small yield to the 6.92-7.12-MeV doublet in $^{16}\mathrm{O}$.[NUCLEAR REACTIONS $^{20}\mathrm{Ne}(\ensuremath{\alpha},2\ensuremath{\alpha})^{16}\mathrm{O}$, $E=78.6$ MeV; measured (${E}_{L},{E}_{R},{\ensuremath{\theta}}_{L},{\ensuremath{\theta}}_{R}$). PWIA analysis.]

Three-Body Quantum Correction to the Free Energy of a Simple Liquid and the Role of Pair and Triplet Potentials in Isotopic Distillation

The lowest-order quantum correction to the partition function and free energy of a simple dense fluid is generalized to take account of many-body forces. The three-body quantum correction is calculated using the triple-dipole potential for the nonadditive interaction, assuming the superposition approximation for the triplet correlation function, and taking the pair correlation functions from x ray and neutron diffraction experiments. In the case of liquid Ar near the triple point, the three-body correction is small enough to be neglected in connection with isotopic distillation experiments. These experiments provide values for 〈 ∇2U 〉, where U is the total interaction energy of the molecules in the liquid, and the results can be used in conjunction with experimental radial distribution functions to test empirical pair potentials u(r) for the Ar—Ar interaction. Several forms of u(r) are investigated and the Barker—Pompe, Kingston, and (exp-6) potentials are found to give the best results for 〈 ∇2U〉. The values of 〈 ∇2U 〉 test the repulsive region of the potential and are much less sensitive to the form of u(r) than is the vapor pressure of the liquid near the triple point. The vapor-pressure and isotopic-distillation tests are compared.

Studies on American Paragonimiasis. IV. Observations on the Pairing of Adult Worms in Laboratory Infections of Domestic Cats

Observations are reported on the pairing of Paragonimus kellicotti Ward, 1908, in laboratory infections of 19 domestic cats. In four of six cases in which single metacercariae were fed 8 weeks previous to subsequent reexposure to another metacercaria, the worms were able to locate one another and become established in the lung cyst of the definitive host and the infections became patent. The role of pairing and the attraction between worms is discussed. During work on Paragonimus kellicotti Ward, 1908, being conducted in my laboratory, an effort was made to study the pairing of adult worms in the lung cyst of the domestic cat.