48,026 research outputs found
Instanton constraints and renormalization
The renormalization is investigated of one-loop quantum fluctuations around a
constrained instanton in -theory with negative coupling. It is found
that the constraint should be renormalized also. This indicates that in general
only renormalizable constraints are permitted.Comment: 29 page
A Melanic Pieris Rapae from Michigan (Lepidoptera: Pierdae)
The Arthur J. Yates collection of Michigan Lepidoptera, recently donated to Michigan State University (see Fischer, 1967), contained a striking melanic male cabbage butterfly [Pieris rapae (Linnaeus)] (Figs. 1, 2) now incorporated into the MSU series. Yates collected the specimen on 29 May 1934 in Roseville, Macomb County, near the western shore of Lake St. Clair in southeastern Michigan. An examination of the androconia and genitalia, using the characters described by Chang (1963), assured proper identification of the specimen. Although we have found no record of a similar rapae taken in North America, there are some named European forms of various species of Pieris that resemble our specimen
The WIYN Open Cluster Study Photometric Binary Survey: Initial Findings for NGC 188
The WIYN open cluster study (WOCS) has been working to yield precise
magnitudes in the Johnson-Kron-Cousins UBVRI system for all stars in the field
of a selection of ``prototypical'' open clusters. Additionally, WOCS is using
radial velocities to obtain orbit solutions for all cluster binary stars with
periods of less than 1000 days. Recently, WOCS is being expanded to include the
near-infrared JHK_s (deep ground-based plus 2MASS) and mid-infrared ([3.6],
[4.5], [5.8], [8.0]) photometry from Spitzer/IRAC observations. This
multi-wavelength data (0.3--8.0 microns) allows us photometrically to identify
binaries, with mass ratios from 1.0--0.3, across a wide range of primary
masses. The spectral energy distribution (SED) fitter by Robitaille et al.
(2007) is used to fit the fluxes of 10--12 bands, converted from the observed
magnitudes, to Kurucz stellar models. Using this photometric technique, we find
that NGC 188 has a binary fraction of 36--49% and provide a star-by-star
comparison to the WOCS radial velocity-based binary study.Comment: 2 pages, 2 figures, Conference Proceedings from "Dynamical Evolution
of Dense Stellar Systems'', IAU Symposium 246, Eds. E. Vesperini, M. Giersz,
& A. Sill
Quantum information reclaiming after amplitude damping
We investigate the quantum information reclaim from the environment after
amplitude damping has occurred. In particular we address the question of
optimal measurement on the environment to perform the best possible correction
on two and three dimensional quantum systems. Depending on the dimension we
show that the entanglement fidelity (the measure quantifying the correction
performance) is or is not the same for all possible measurements and uncover
the optimal measurement leading to the maximum entanglement fidelity
A model for the anisotropic response of fibrous soft tissues using six discrete fibre bundles
The development of accurate constitutive models of fibrous soft-tissues is a challenging problem. Many consider the tissue to be a collection of fibres with a continuous distribution function representing their orientations. A novel discrete fibre model is presented consisting of six weighted fibre bundles. Each bundle is oriented such that they pass through opposing vertices of a regular icosahedron. A novel aspect of the model is the use of simple analytical distribution functions to simulate the undulated collagen fibres. This approach yields a closed form analytical expression for the strain energy function for the collagen fibre bundle that avoids the sometimes costly numerical integration of some statistical distribution functions. The elastin fibres are characterized by a neo-Hookean strain energy function. The model accurately simulates the biaxial stretching of rabbit-skin (error-of-fit 8.7%), the uniaxial stretching of pig-skin (error-of-fit 7.6%), equibiaxial loading of aortic valve cusp (error-of-fit 0.8%), and the simple shear of rat septal myocardium (error-of-fit 9.1%). The proposed model compares favourably with previously published soft-tissue models and alternative methods of representing undulated collagen fibres. The stiffness of collagen fibres predicted by the model ranges from 8.0 MPa to 0.93 GPa. The stiffness of elastin fibres ranges from 2.5 kPa to 154.4 kPa. The anisotropy of model resulting from the representation of the fibre field with a discrete number of fibres is also explored
Entanglement Detection Using Majorization Uncertainty Bounds
Entanglement detection criteria are developed within the framework of the
majorization formulation of uncertainty. The primary results are two theorems
asserting linear and nonlinear separability criteria based on majorization
relations, the violation of which would imply entanglement. Corollaries to
these theorems yield infinite sets of scalar entanglement detection criteria
based on quasi-entropic measures of disorder. Examples are analyzed to probe
the efficacy of the derived criteria in detecting the entanglement of bipartite
Werner states. Characteristics of the majorization relation as a comparator of
disorder uniquely suited to information-theoretical applications are emphasized
throughout.Comment: 10 pages, 1 figur
Ginsparg-Wilson Relation and Ultralocality
It is shown that it is impossible to construct a free theory of fermions on
infinite hypercubic Euclidean lattice in four dimensions that is: (a)
ultralocal, (b) respects symmetries of hypercubic lattice, (c) corresponding
kernel satisfies D gamma5 + gamma5 D = D gamma5 D (Ginsparg-Wilson relation),
(d) describes single species of massless Dirac fermions in the continuum limit.Comment: 4 pages, REVTEX; few minor change
Optimal control of a leaking qubit
Physical implementations of quantum bits can contain coherent transitions to
energetically close non-qubit states. In particular, for anharmonic oscillator
systems such as the superconducting phase qubit and the transmon a two-level
approximation is insufficient. We apply optimal control theory to the envelope
of a resonant Rabi pulse in a qubit in the presence of a single, weakly
off-resonant leakage level. The gate error of a spin flip operation reduces by
orders of magnitude compared to simple pulse shapes. Near-perfect gates can be
achieved for any pulse duration longer than an intrinsic limit given by the
nonlinearity. The pulses can be understood as composite sequences that refocus
the leakage transition. We also discuss ways to improve the pulse shapes.Comment: 4 pages, 2 figure
Entanglement of a Laguerre-Gaussian cavity mode with a rotating mirror
It has previously been shown theoretically that the exchange of linear
momentum between the light field in an optical cavity and a vibrating end
mirror can entangle the electromagnetic field with the vibrational motion of
that mirror. In this paper we consider the rotational analog of this situation
and show that radiation torque can similarly entangle a Laguerre-Gaussian
cavity mode with a rotating end mirror. We examine the mirror-field
entanglement as a function of ambient temperature, radiation detuning and
orbital angular momentum carried by the cavity mode.Comment: 5 figures, 1 table, submitted to Phys.Rev.
- …