On the clarity of the musical stave

The staves of 63 scores of popular keyboard music from 50 publishers were measured. The staves had similar height but lines that varied in thickness from 0.1 mm to 0.45 mm. Evidence from visual psychophysics suggests that when the stave has thick lines, perceptual distortions are likely to affect the clarity of the score adversely. Students were asked to sight-read scores comprising random notes (“chromatic”) or random notes in the key of G. The scores had staves with lines that were 0.1 mm or 0.4 mm thick (current typographic practice). Twice as many errors were made when the staves had thick lines, although the scores were then read more slowly. Scores in the key of G were read more accurately than the “chromatic” scores, but those with thick lines were read with as many errors as “chromatic” scores with thin lines. There was a tendency for individuals with susceptibility to pattern glare to read the scores with thick lines relatively slowly. The findings suggest that perceptual distortions can impair sight-reading of music manuscript because of the pattern from the lines of the stave; using thinner lines can increase both sight reading accuracy and speed. </jats:p

Radiolarian faunal characteristics in Oligocene of the Kerguelen Plateau, Leg 183, Site 1138

Three sites from Ocean Drilling Program (ODP) Leg 183 (Kerguelen Plateau) have been analyzed to document faunal change in high-latitude radiolarians and to compare the faunal change to Eocene-Oligocene climatic deterioration. Radiolarians are not preserved in Eocene sediments. In Oligocene sediments, radiolarian preservation improves in a stepwise manner toward the Miocene. A total of 115 species were found in lower Oligocene samples from Site 1138; all are documented herein. Radiolarian preservation is presumably linked to productivity triggered by climatic cooling during the early Oligocene. Similar patterns of improving preservation through the Eocene/Oligocene boundary are documented from several Deep Sea Drilling Project and ODP sites in the Southern Ocean, indicating a general pattern. In contrast to the Southern Kerguelen Plateau, however, proxies for productivity are more divergent at Site 1138 (Central Kerguelen Plateau). Whereas carbonate dissolution, as indicated by poor preservation of foraminifers and common hiatuses, is very pronounced in the upper Eocene-lowermost Oligocene, the quality of radiolarian and diatom preservation does not significantly increase until the uppermost lower Oligocene. Multiple measures of radiolarian diversity in the Oligocene from Site 1138 closely parallel radiolarian preservation, indicating that preserved radiolarian diversity is controlled by productivity

Comment on "Spin relaxation in quantum Hall systems"

W. Apel and Yu.A. Bychkov have recently considered the spin relaxation in a 2D quantum Hall system for the filling factor close to unity [PRL v.82, 3324 (1999)]. The authors considered only one spin flip mechanism (direct spin-phonon coupling) among several possible spin-orbit related ones and came to the conclusion that the spin relaxation time due to this mechanism is quite short: around $10^{-10}$ s at B=10 T (for GaAs). This time is much shorter than the typical time ($10^{-5}$ s) obtained earlier by D. Frenkel while considering the spin relaxation of 2D electrons in a quantizing magnetic field without the Coulomb interaction and for the same spin-phonon coupling. I show that the authors' conclusion about the value of the spin-flip time is wrong and have deduced the correct time which is by several orders of magnitude longer. I also discuss the admixture mechanism of the spin-orbit interaction.Comment: 1 pag

Quantum Hall Ferromagnets: Induced Topological term and electromagnetic interactions

The $\nu = 1$ quantum Hall ground state in materials like GaAs is well known to be ferromagnetic in nature. The exchange part of the Coulomb interaction provides the necessary attractive force to align the electron spins spontaneously. The gapless Goldstone modes are the angular deviations of the magnetisation vector from its fixed ground state orientation. Furthermore, the system is known to support electrically charged spin skyrmion configurations. It has been claimed in the literature that these skyrmions are fermionic owing to an induced topological Hopf term in the effective action governing the Goldstone modes. However, objections have been raised against the method by which this term has been obtained from the microscopics of the system. In this article, we use the technique of the derivative expansion to derive, in an unambiguous manner, the effective action of the angular degrees of freedom, including the Hopf term. Furthermore, we have coupled perturbative electromagnetic fields to the microscopic fermionic system in order to study their effect on the spin excitations. We have obtained an elegant expression for the electromagnetic coupling of the angular variables describing these spin excitations.Comment: 23 pages, Plain TeX, no figure

Massive Spin Collective Mode in Quantum Hall Ferromagnet

It is shown that the collective spin rotation of a single Skyrmion in quantum Hall ferromagnet can be regarded as precession of the entire spin texture in the external magnetic field, with an effective moment of inertia which becomes infinite in the zero g-factor limit. This low-lying spin excitation may dramatically enhance the nuclear spin relaxation rate via the hyperfine interaction in the quantum well slightly away from filling factor equal one.Comment: 4 page

Delocalization in Coupled Luttinger Liquids with Impurities

We study effects of quenched disorder on coupled two-dimensional arrays of Luttinger liquids (LL) as a model for stripes in high-T_c compounds. In the framework of a renormalization-group analysis, we find that weak inter-LL charge-density-wave couplings are always irrelevant as opposed to the pure system. By varying either disorder strength, intra- or inter-LL interactions, the system can undergo a delocalization transition between an insulator and a novel strongly anisotropic metallic state with LL-like transport. This state is characterized by short-ranged charge-density-wave order, the superconducting order is quasi long-ranged along the stripes and short-ranged in the transversal direction.Comment: 6 pages, 5 figures, substantially extended and revised versio

Is there a renormalization of the 1D conductance in Luttinger Liquid model?

Properties of 1D transport strongly depend on the proper choice of boundary conditions. It has been frequently stated that the Luttinger Liquid (LL) conductance is renormalized by the interaction as $g \frac{e^2} {h}$. To contest this result I develop a model of 1D LL wire with the interaction switching off at the infinities. Its solution shows that there is no renormalization of the universal conductance while the electrons have a free behavior in the source and drain reservoirs.Comment: 5 pages, RevTex 2.0, attempted repair of tex error