5,935 research outputs found
Comment on `On the Quantum Theory of Molecules' [J. Chem.Phys. {\bf 137}, 22A544 (2012)]
In our previous paper [J. Chem.Phys. {\bf 137}, 22A544 (2012)] we argued that
the Born-Oppenheimer approximation could not be based on an exact
transformation of the molecular Schr\"{o}dinger equation. In this Comment we
suggest that the fundamental reason for the approximate nature of the
Born-Oppenheimer model is the lack of a complete set of functions for the
electronic space, and the need to describe the continuous spectrum using
spectral projection.Comment: 2 page
An electronic Mach-Zehnder interferometer in the Fractional Quantum Hall effect
We compute the interference pattern of a Mach-Zehnder interferometer
operating in the fractional quantum Hall effect. Our theoretical proposal is
inspired by a remarkable experiment on edge states in the Integer Quantum Hall
effect (IQHE). The Luttinger liquid model is solved via two independent
methods: refermionization at nu=1/2 and the Bethe Ansatz solution available for
Laughlin fractions. The current differs strongly from that of single electrons
in the strong backscattering regime. The Fano factor is periodic in the flux,
and it exhibits a sharp transition from sub-Poissonian (charge e/2) to
Poissonian (charge e) in the neighborhood of destructive interferences
Indeterminacy of Holographic Quantum Geometry
An effective theory based on wave optics is used to describe indeterminacy of
position in holographic spacetime with a UV cutoff at the Planck scale.
Wavefunctions describing spacetime positions are modeled as complex
disturbances of quasi-monochromatic radiation. It is shown that the product of
standard deviations of two position wavefunctions in the plane of a holographic
light sheet is equal to the product of their normal separation and the Planck
length. For macroscopically separated positions the transverse uncertainty is
much larger than the Planck length, and is predicted to be observable as a
"holographic noise" in relative position with a distinctive shear spatial
character, and an absolutely normalized frequency spectrum with no parameters
once the fundamental wavelength is fixed from the theory of gravitational
thermodynamics. The spectrum of holographic noise is estimated for the GEO600
interferometric gravitational-wave detector, and is shown to approximately
account for currently unexplained noise between about 300 and 1400Hz. In a
holographic world, this result directly and precisely measures the fundamental
minimum interval of time.Comment: 4 pages, LaTeX. Considerably shortened from earlier version.
Conclusions are unchanged. Submitted to PR
Large tunable photonic band gaps in nanostructured doped semiconductors
A plasmonic nanostructure conceived with periodic layers of a doped
semiconductor and passive semiconductor is shown to generate spontaneously
surface plasmon polaritons thanks to its periodic nature. The nanostructure is
demonstrated to behave as an effective material modeled by a simple dielectric
function of ionic-crystal type, and possesses a fully tunable photonic band
gap, with widths exceeding 50%, in the region extending from mid-infra-red to
Tera-Hertz.Comment: 6 pages, 4 figures, publishe
Superconductivity in Boron under pressure - why are the measured T's so low?
Using the full potential linear muffin-tin orbitals (FP-LMTO) method we
examine the pressure-dependence of superconductivity in the two metallic phases
of Boron: bct and fcc. Linear response calculations are carried out to examine
the phonon frequencies and electron-phonon coupling for various lattice
parameters, and superconducting transition temperatures are obtained from the
Eliashberg equation. In both bct and fcc phases the superconducting transition
temperature T is found to decrease with increasing pressure, due to
stiffening of phonons with an accompanying decrease in electron-phonon
coupling. This is in contrast to a recent report, where T is found to
increase with pressure. Even more drastic is the difference between the
measured T, in the range 4-11 K, and the calculated values for both bct and
fcc phases, in the range 60-100 K. The calculation reveals that the transition
from the fcc to bct phase, as a result of increasing volume or decreasing
pressure, is caused by the softening of the X-point transverse phonons. This
phonon softening also causes large electron-phonon coupling for high volumes in
the fcc phase, resulting in coupling constants in excess of 2.5 and T
nearing 100 K. We discuss possible causes as to why the experiment might have
revealed T's much lower than what is suggested by the present study. The
main assertion of this paper is that the possibility of high T, in excess
of 50 K, in high pressure pure metallic phases of boron cannot be ruled out,
thus substantiating the need for further experimental investigations of the
superconducting properties of high pressure pure phases of boron.Comment: 16 pages, 8 figures, 1 Tabl
A code to unfold scintillation spectrometer polyenergetic gamma photon experimental distributions
FORTRAN code to unfold sodium iodide scintillation spectrometer polyenergetic gamma photon experimental distribution
Asymptotic Search for Ground States of SU(2) Matrix Theory
We introduce a complete set of gauge-invariant variables and a generalized
Born-Oppenheimer formulation to search for normalizable zero-energy asymptotic
solutions of the Schrodinger equation of SU(2) matrix theory. The asymptotic
method gives only ground state candidates, which must be further tested for
global stability. Our results include a set of such ground state candidates,
including one state which is a singlet under spin(9).Comment: 51 page
The effect of cultural orientation and leadership style on self- versus other-oriented organizational citizenship behavior in Turkey and the Netherlands
This paper investigated the effects of a paternalistic and empowering leadership style on organizational citizenship behaviour (OCB) in an experimental design using 100 Turkish and 100 Dutch students who held part-time jobs. Confirming our expectations, a paternalistic leadership style had a more positive effect on job dedication and organizational support in Turkey than in the Netherlands. Contradicting our expectations, an empowering leadership style did not have a more positive effect on any of the OCB dimensions in the Netherlands than it did in Turkey. However, in the Netherlands an empowering leadership style had a stronger effect on interpersonal facilitation, job dedication, and organizational support than a paternalistic leadership style. Paternalistic and empowering leadership styles both had positive effects on OCB dimensions in Turkey. As expected, collectivism moderated the relationship between paternalistic leadership style and other oriented OCB (i.e., interpersonal facilitation). Specifically, people who had more collectivistic tendencies were more positively influenced by a paternalistic leader than people who had low collectivistic tendencies in both countries. However, individualism did not have any moderating effects on the relationship between empowering leadership style and self-oriented OCB (i.e., job dedication). Our findings are relevant for understanding the effects of leadership styles and cultural orientations on self- versus other-oriented OCB in Turkey and the Netherlands
Dynamics of the Born-Infeld dyons
The approach to the dynamics of a charged particle in the Born-Infeld
nonlinear electrodynamics developed in [Phys. Lett. A 240 (1998) 8] is
generalized to include a Born-Infeld dyon. Both Hamiltonian and Lagrangian
structures of many dyons interacting with nonlinear electromagnetism are
constructed. All results are manifestly duality invariant.Comment: 11 pages, LATE
Maps of complex motion selectivity in the superior temporal cortex of the alert macaque monkey: a double-label 2-deoxyglucose study
The superior temporal sulcus (STS) of the macaque monkey contains multiple visual areas. Many neurons within these regions respond selectively to motion direction and to more complex motion patterns, such as expansion, contraction and rotation. Single-unit recording and optical recording studies in MT/MST suggest that cells with similar tuning properties are clustered into columns extending through multiple cortical layers. In this study, we used a double-label 2-deoxyglucose technique in awake, behaving macaque monkeys to clarify this functional organization. This technique allowed us to label, in a single animal, two populations of neurons responding to two different visual stimuli. In one monkey we compared expansion with contraction; in a second monkey we compared expansion with clockwise rotation. Within the STS we found a patchy arrangement of cortical columns with alternating stimulus selectivity: columns of neurons preferring expansion versus contraction were more widely separated than those selective for expansion versus rotation. This mosaic of interdigitating columns on the floor and posterior bank of the STS included area MT and some neighboring regions of cortex, perhaps including area MST
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