8,867 research outputs found
Nonlinear phononic crystals based on chains of disks alternating with toroidal structures
We study experimentally the acoustic response of a load-bearing, phononic crystal composed of alternating steel disks, and polytetrafluoroethylene o-rings under precompression. The crystal allows for axial, rocking, and shear-polarized wavemodes when excited by a broad-band signal applied off-axis. Finite element analysis is employed to determine the system’s wave modes. The nonlinear interaction between disks and o-rings supports a dynamic response that is tunable with variations in static precompression, leading to controllable frequency shifts in a large band gap. A modal analysis reveals that four of the six principal wave modes are susceptible to external precompression while two modes are not
A Groenewold-Van Hove Theorem for S^2
We prove that there does not exist a nontrivial quantization of the Poisson
algebra of the symplectic manifold S^2 which is irreducible on the subalgebra
generated by the components {S_1,S_2,S_3} of the spin vector. We also show that
there does not exist such a quantization of the Poisson subalgebra P consisting
of polynomials in {S_1,S_2,S_3}. Furthermore, we show that the maximal Poisson
subalgebra of P containing {1,S_1,S_2,S_3} that can be so quantized is just
that generated by {1,S_1,S_2,S_3}.Comment: 20 pages, AMSLaTe
Constrained Dynamics for Quantum Mechanics I. Restricting a Particle to a Surface
We analyze constrained quantum systems where the dynamics do not preserve the
constraints. This is done in particular for the restriction of a quantum
particle in Euclidean n-space to a curved submanifold, and we propose a method
of constraining and dynamics adjustment which produces the right Hamiltonian on
the submanifold when tested on known examples. This method we hope will become
the germ of a full Dirac algorithm for quantum constraints. We take a first
step in generalising it to the situation where the constraint is a general
selfadjoint operator with some additional structures.Comment: 49 pages, TEX, input files amssym.def, amssym.te
The effects of moral disengagement mechanisms on doping likelihood are mediated by guilt and moderated by moral traits
Objectives
We examined the effects of moral disengagement on doping likelihood and guilt, and determined whether the effects of moral disengagement on doping likelihood were mediated by guilt and moderated by moral traits.
Design
We used an experimental design to compare the effects of moral disengagement mechanisms on doping likelihood and guilt in hypothetical situations.
Method
Athletes indicated their doping likelihood and anticipated guilt in situations describing one of six moral disengagement mechanisms (moral justification, advantageous comparison, euphemistic labeling, distortion of consequences, displacement of responsibility, diffusion of responsibility) and in neutral (control) situations. They also completed measures of moral agency, identity, perfectionism, and values, to which we refer collectively as moral traits.
Results
Doping likelihood was higher in all six moral disengagement situations compared to neutral situations. Anticipated guilt was lower in five moral disengagement situations (except euphemistic labeling) compared to neutral situations. Doping likelihood and anticipated guilt differed among the moral disengagement mechanisms. The effect of five moral disengagement mechanisms (except euphemistic labeling) on doping likelihood was mediated by anticipated guilt. The effect of overall moral disengagement on doping likelihood was moderated by moral agency, moral perfectionism and moral values.
Conclusions
Moral disengagement increased the likelihood of doping and decreased affective self-sanction for doping as predicted by the theory of moral thought and action. The finding that the effects of moral disengagement on doping likelihood were moderated by moral agency, moral perfectionism and moral values highlights the role played by moral traits to restrain dishonest conduct in sport
Glueball Spin
The spin of a glueball is usually taken as coming from the spin (and possibly
the orbital angular momentum) of its constituent gluons. In light of the
difficulties in accounting for the spin of the proton from its constituent
quarks, the spin of glueballs is reexamined. The starting point is the
fundamental QCD field angular momentum operator written in terms of the
chromoelectric and chromomagnetic fields. First, we look at the restrictions
placed on the structure of glueballs from the requirement that the QCD field
angular momentum operator should satisfy the standard commutation
relationships. This can be compared to the electromagnetic charge/monopole
system, where the quantization of the field angular momentum places
restrictions (i.e. the Dirac condition) on the system. Second, we look at the
expectation value of this operator under some simplifying assumptions.Comment: 11 pages, 0 figures; added references and some discussio
Female attraction to male muscle mass across the menstrual cycle.
The current project investigated female attraction to male muscle mass across the menstrual cycle. On four separate occasions in a five week period, female participants rated the attractiveness of images of male bodies. Images included four different levels of muscle mass: low muscle, medium muscle, high muscle, and extremely high muscle. It was hypothesized that females would rate the high and the extremely high muscle mass images higher in attractiveness when ovulating than when not ovulating. It was also hypothesized that females would rate the low muscle mass images low in attractiveness regardless of ovulatory status. Results revealed no significant interaction between ovulatory status and ratings of muscle mass. However, there was a significant main effect for muscle mass. Extremely high muscle images were rated significantly higher than both medium muscle images and low muscle images. High muscle images were rated significantly higher than both medium muscle images and low muscle images. Medium muscle images were rated significantly lower than both extremely high muscle images and high muscle images, but higher than low muscle images. Low muscle images were rated significantly lower than extremely high muscle images, high muscle images, and medium muscle images, each. It seems that muscle mass is not one of the indications of testosterone level that females use to evaluate mates. Additionally, females do not appear to be highly attracted to males with very low muscle mass, regardless of ovulatory status
The 6-vertex model of hydrogen-bonded crystals with bond defects
It is shown that the percolation model of hydrogen-bonded crystals, which is
a 6-vertex model with bond defects, is completely equivalent with an 8-vertex
model in an external electric field. Using this equivalence we solve exactly a
particular 6-vertex model with bond defects. The general solution for the
Bethe-like lattice is also analyzed.Comment: 13 pages, 6 figures; added references for section
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