17,473 research outputs found
Demographic and psychological variables affecting test subject evaluations of ride quality
Ride-quality experiments similar in objectives, design, and procedure were conducted, one using the U.S. Air Force Total In-Flight Simulator and the other using the Langley Passenger Ride Quality Apparatus to provide the motion environments. Large samples (80 or more per experiment) of test subjects were recruited from the Tidewater Virginia area and asked to rate the comfort (on a 7-point scale) of random aircraft motion typical of that encountered during STOL flights. Test subject characteristics of age, sex, and previous flying history (number of previous airplane flights) were studied in a two by three by three factorial design. Correlations were computed between one dependent measure, the subject's mean comfort rating, and various demographic characteristics, attitudinal variables, and the scores on Spielberger's State-Trait Anxiety Inventory. An effect of sex was found in one of the studies. Males made higher (more uncomfortable) ratings of the ride than females. Age and number of previous flights were not significantly related to comfort ratings. No significant interactions between the variables of age, sex, or previous number of flights were observed
QED2 as a testbed for interpolations between quenched and full QCD
Lattice QED2 with the Wilson formulation of fermions is used as a convenient
model system to study artifacts of the quenched approximation on a finite
lattice. The quenched functional integral is shown to be ill-defined in this
system as a consequence of the appearance of exactly real modes for physical
values of the fermion mass.
The location and frequency of such modes is studied as a function of lattice
spacing, lattice volume, topological charge and improved action parameters. The
efficacy of the recently proposed modified quenched approximation is examined,
as well as a new approach to the interpolation from the quenched to full
dynamical theory employing a truncated form of the fermion determinant.Comment: Talk presented by A. Duncan at LATTICE97 (theoretical developments
The eta-prime propagator in quenched QCD
The calculation of the eta-prime hairpin diagram is carried out in the
modified quenched approximation (MQA) in which the lattice artifact which
causes exceptional configurations is removed by shifting observed poles at
kappa<kappa_c in the quark propagators to the critical value of hop ping
parameter. By this method, the eta-prime propagator can be accurately
calculated even for very light quark mass. A determination of the topological
susceptibility for quenched QCD is also obtained, using the fermionic method of
Smit and Vink to calculate winding numbers.Comment: 3 pages, 3 postscript figure
Low Dirac Eigenmodes and the Topological and Chiral Structure of the QCD Vacuum
Several lattice calculations which probe the chiral and topological structure
of QCD are discussed. The results focus attention on the low-lying eigenmodes
of the Dirac operator in typical gauge field configurations.Comment: Talk presented at the DPF2000 Conferenc
Partitioning of a polymer chain between a confining cavity and a gel
A lattice field theory approach to the statistical mechanics of charged
polymers in electrolyte solutions [S. Tsonchev, R. D. Coalson, and A. Duncan,
Phys. Rev. E 60, 4257, (1999)] is applied to the study of a polymer chain
contained in a spherical cavity but able to diffuse into a surrounding gel. The
distribution of the polymer chain between the cavity and the gel is described
by its partition coefficient, which is computed as a function of the number of
monomers in the chain, the monomer charge, and the ion concentrations in the
solution.Comment: 17 pages, 6 figure
Evidence for quenched chiral logs
Using the pole shifting procedure of the modified quenched approximation
(MQA) to cure the exceptional configuration problem, accurate hadron hadron
spectrum calculations can be obtained at very light quark mass. Here we use the
MQA to extend and improve our previous investigation of chiral logs in the pion
mass. At beta=5.7 for Wilson fermion, we see clear evidence for quenched chiral
logarithms in the pion mass as a function of quark mass. The size of the
observed chiral log exponent delta is in good agreement with the value obtained
from a direct calculation of the eta' hairpin diagram.Comment: 3 pages, 4 figures, Lattice 98 tal
Scattering of a Light Beam from Waves at an Air-Sea Interface
The authors report a new theory that describes the scattering of an upward propagating laser beam from the sea through the air-sea interface in the presence of sea waves. The sea is assumed to be a uniform dielectric and conventional scattering theory is employed by using a modification to the first Born approximation that permits treatment of surface refraction phenomena. Methods of statistical radiometry are also used in a new manner by assuming that the surface scattering function for the sea waves can be treated by a quasi-homogeneous source model to calculate the second-order correlation functions for the partially coherent scattered field. These correlation functions yield a simple expression for the radiant intensity of the scattered field as the convolution of the Fourier transform of the complex degree of spectral coherence for the sea waves with the squared modulus of the angular spectrum of plane waves for the incident laser beam. We believe that this theory is a significant improvement over the models that are usually used for modeling this phenomenon
Information Security Policy Development for Caribbean Financial Institutions
Governments of English-speaking Caribbean countries have begun to place greater emphasis on e-government to reduce bureaucratic inefficiencies and are encouraging, through legislation and other inducements, the expansion of e-commerce operations in order to enhance global competitiveness. This has expectedly led to a greater movement of data and with it information security risks. Information security managers continue to grapple with the difficulty of reengineering policies and standards to meet this new reality. Hence many Caribbean organizations have become more vulnerable to security risks that are initiated internally. This is of grave concern to the Financial Institutions of the Caribbean as they prepare to offer extended services in order to exploit the opportunities expected from the introduction of the Caribbean Single Market and Economy. In addition, these institutions attempt to increase their share of both remittances from the Caribbean Diaspora and foreign direct investments which also serve to exacerbate these issues. These organizations are less capable of stemming the tide of fraud through identity theft and by other means, which are on the rise globally. In most cases these acts are facilitated (inadvertently or deliberately) by the actions of insiders. This paper proposes an approach to the development of context-based information security policies for Caribbean Financial Institutions aimed at mitigating insider risks
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