Zero torque gear head wrench

A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed

Bolt installation tool for tightening large nuts and bolts

Large bolts and nuts are accurately tightened to structures without damaging torque stresses. There are two models of bolt installation tool. One is rigidly mounted and one is hand held. Each model includes torque-multiplier unit

High Frequency Behavior of the Infrared Conductivity of Cuprates

We analyze recent infrared conductivity data in the normal state of the cuprates. We find that the high frequency behavior, which has been suggested as evidence for quantum critical scaling, is generally characteristic of electrons interacting with a broad spectrum of bosons. From explicit calculations, we find a frequency exponent for the modulus of the conductivity, and a phase angle, in good agreement with experiment. The data indicate an upper cut-off of the boson spectrum of order 300 meV. This implies that the bosons are of electronic origin rather than phonons.Comment: 4 page

Linear Response Theory and the Universal Nature of the Magnetic Excitation Spectrum of the Cuprates

Linear response theory, commonly known as the random phase approximation (RPA), predicts a rich magnetic excitation spectrum for d-wave superconductors. Many of the features predicted by such calculations appear to be reflected in inelastic neutron scattering data of the cuprates. In this article, I will present results from RPA calculations whose input is based on angle resolved photoemission data, and discuss possible relevance to inelastic neutron scattering data of LSCO, YBCO, and Bi2212 in their superconducting and non-superconducting phases. In particular, the question of the universality of the magnetic excitation spectrum will be addressed.Comment: 9 pages, 13 figure

Incoherent pair tunneling in the pseudogap phase of cuprates

Motivated by a recent experiment by Bergeal et al., we reconsider incoherent pair tunneling in a cuprate junction formed from an optimally doped superconducting lead and an underdoped normal metallic lead. We study the impact of the pseudogap on the pair tunneling by describing fermions in the underdoped lead with a model self-energy that has been developed to reproduce photoemission data. We find that the pseudogap causes an additional temperature dependent suppression of the pair contribution to the tunneling current. We discuss consistency with available experimental data and propose future experimental directions.Comment: 5 pages, 3 figure

Odd Parity and Line Nodes in Heavy Fermion Superconductors

Group theory arguments have demonstrated that a general odd parity order parameter cannot have line nodes in the presence of spin-orbit coupling. In this paper, it is shown that these arguments do not hold on the $k_z = \pi/c$ zone face of a hexagonal close packed lattice. In particular, three of the six odd parity representations vanish identically on this face. This has potential relevance to the heavy fermion superconductor $UPt_3$.Comment: 5 pages, revte

The Temperature Evolution of the Spectral Peak in High Temperature Superconductors

Recent photoemission data in the high temperature cuprate superconductor Bi2212 have been interpreted in terms of a sharp spectral peak with a temperature independent lifetime, whose weight strongly decreases upon heating. By a detailed analysis of the data, we are able to extract the temperature dependence of the electron self-energy, and demonstrate that this intepretation is misleading. Rather, the spectral peak loses its integrity above Tc due to a large reduction in the electron lifetime.Comment: 5 pages, revtex, 4 encapsulated postscript figure

Quasiparticle mirages in the tunneling spectra of d-wave superconductors

We illustrate the importance of many-body effects in the Fourier transformed local density of states (FT-LDOS) of d-wave superconductors from a model of electrons coupled to an Einstein mode with energy Omega_0. For bias energies significantly larger than Omega_0 the quasiparticles have short lifetimes due to this coupling, and the FT-LDOS is featureless if the electron-impurity scattering is treated within the Born approximation. In this regime it is important to include boson exchange for the electron-impurity scattering which provides a `step down' in energy for the electrons and allows for long lifetimes. This many-body effect produces qualitatively different results, namely the presence of peaks in the FT-LDOS which are mirrors of the quasiparticle interference peaks which occur at bias energies smaller than ~ Omega_0. The experimental observation of these quasiparticle mirages would be an important step forward in elucidating the role of many-body effects in FT-LDOS measurements.Comment: revised text with new figures, to be published, Phys Rev