518 research outputs found
Proof of Jacobi identity in generalized quantum dynamics
We prove that the Jacobi identity for the generalized Poisson bracket is
satisfied in the generalization of Heisenberg picture quantum mechanics
recently proposed by one of us (SLA). The identity holds for any combination of
fermionic and bosonic fields, and requires no assumptions about their mutual
commutativity.Comment: 9 pages, plain tex file, IASSNS-HEP-93/4
Putting Social Rewards And Identity Salience To The Test: Evidence From A Field Experiment On Teachers In Philadelphia
We partnered with the School District of Philadelphia (SDP) to run a randomized experiment testing interventions to increase teacher participation in an annual feedback survey, an uncompensated task that requires a teacher’s time but helps the educational system overall. Our experiment varied the nature of the incentive scheme used, and the associated messaging. In the experiment, all 8,062 active teachers in the SDP were randomly assigned to receive one of four emails using a 2x2 experimental design; specifically, teachers received a lottery-based financial incentive to complete the survey that was either personal (a chance to win one of fifteen 100 gift cards for supplies for their students), and also received email messaging that either did or did not make salient their identity as an educator. Despite abundant statistical power, we find no discernible differences across our conditions on survey completion rates. One implication of these null results is that from a public administration perspective, social rewards may be preferable since funds used for this purpose by school districts go directly to students (through increased expenditure on student supplies), and do not seem less efficacious than personal financial incentives for teachers
Fast vectorized algorithm for the Monte Carlo Simulation of the Random Field Ising Model
An algoritm for the simulation of the 3--dimensional random field Ising model
with a binary distribution of the random fields is presented. It uses
multi-spin coding and simulates 64 physically different systems simultaneously.
On one processor of a Cray YMP it reaches a speed of 184 Million spin updates
per second. For smaller field strength we present a version of the algorithm
that can perform 242 Million spin updates per second on the same machine.Comment: 13 pp., HLRZ 53/9
Application of exchange Monte Carlo method to ordering dynamics
We apply the exchange Monte Carlo method to the ordering dynamics of the
three-state Potts model with the conserved order parameter. Even for the deeply
quenched case to low temperatures, we have observed a rapid domain growth; we
have proved the efficiency of the exchange Monte Carlo method for the ordering
process. The late-stage growth law has been found to be for
the case of conserved order parameter of three-component system.Comment: 7 pages including 5 eps figures, to appear in New J. Phys.
http://www.njp.or
Heavy quark potential and quarkonia dissociation rates
Quenched lattice data for the quark-antiquark interaction (in terms of heavy
quark free energies) in the color singlet channel at finite temperatures are
fitted and used within the nonrelativistic Schroedinger equation formalism to
obtain binding energies and scattering phase shifts for the lowest eigenstates
in the charmonium and bottomonium systems in a hot gluon plasma. The partial
dissociation rate due to the Bhanot-Peskin process is calculated using
different assumptions for the gluon distribution function, including free
massless gluons, massive gluons, and massive damped gluons. It is demonstrated
that a temperature dependent gluon mass has an essential influence on the heavy
quarkonia dissociation, but that this process alone is insufficient to describe
the heavy quarkonia dissociation rates.Comment: 4 pages, 5 figures, contribution to the proceedings of the
International Conference on Hard and Electromagnetic Probes of High Energy
Nuclear Collisions, Ericeira, Portugal, Nov. 4-10, 200
Diffusive Thermal Dynamics for the Ising Ferromagnet
We introduce a thermal dynamics for the Ising ferromagnet where the energy
variations occurring within the system exhibit a diffusive character typical of
thermalizing agents such as e.g. localized excitations. Time evolution is
provided by a walker hopping across the sites of the underlying lattice
according to local probabilities depending on the usual Boltzmann weight at a
given temperature. Despite the canonical hopping probabilities the walker
drives the system to a stationary state which is not reducible to the canonical
equilibrium state in a trivial way. The system still exhibits a magnetic phase
transition occurring at a finite value of the temperature larger than the
canonical one. The dependence of the model on the density of walkers realizing
the dynamics is also discussed. Interestingly the differences between the
stationary state and the Boltzmann equilibrium state decrease with increasing
number of walkers.Comment: 9 pages, 14 figures. Accepted for publication on PR
On the question of universality in \RPn and \On Lattice Sigma Models
We argue that there is no essential violation of universality in the
continuum limit of mixed \RPn and \On lattice sigma models in 2 dimensions,
contrary to opposite claims in the literature.Comment: 16 pages (latex) + 3 figures (Postscript), uuencode
Multicanonical Study of the 3D Ising Spin Glass
We simulated the Edwards-Anderson Ising spin glass model in three dimensions
via the recently proposed multicanonical ensemble. Physical quantities such as
energy density, specific heat and entropy are evaluated at all temperatures. We
studied their finite size scaling, as well as the zero temperature limit to
explore the ground state properties.Comment: FSU-SCRI-92-121; 7 pages; sorry, no figures include
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