6,585 research outputs found
Incentives in Religious Performance: a Stochastic Dominance Approach
Using a stochastic dominance approach in an international dataset of about 10,000 Catholic subjects, we show that incentives (based on absolute belief) play a crucial role in religious practice (church attendance and prayer). Furthermore, we find that when both positive (heaven) and negative (hell) incentives are available, the former have a much stronger effect than the latter. The results are confirmed using Kolmogorov-Smirnov tests.Incentives, rewards, punishment, Economics of Religion
Recursive linear estimation for discrete time systems in the presence of different multiplicative observation noises
This paper describes a design for a least mean square error estimator in discrete time systems where the components of the state vector, in measurement equation, are corrupted by different multiplicative noises in addition to observation noise. We show how known results can be considered a particular case of the algorithm stated in this paperState estimation, multiplicative noise, uncertain observations
Non-linear ripple dynamics on amorphous surfaces patterned by ion-beam sputtering
Erosion by ion-beam sputtering (IBS) of amorphous targets at off-normal
incidence frequently produces a (nanometric) rippled surface pattern, strongly
resembling macroscopic ripples on aeolian sand dunes. Suitable generalization
of continuum descriptions of the latter allows us to describe theoretically for
the first time the main nonlinear features of ripple dynamics by IBS, namely,
wavelength coarsening and non-uniform propagation velocity, that agree with
similar results in experiments and discrete models. These properties are seen
to be the anisotropic counterparts of in-plane ordering and (interrupted)
pattern coarsening in IBS experiments on rotating substrates and at normal
incidence.Comment: 5 pages, 3 figure
Coupling of morphology to surface transport in ion-beam irradiated surfaces. I. Oblique incidence
We propose and study a continuum model for the dynamics of amorphizable
surfaces undergoing ion-beam sputtering (IBS) at intermediate energies and
oblique incidence. After considering the current limitations of more standard
descriptions in which a single evolution equation is posed for the surface
height, we overcome (some of) them by explicitly formulating the dynamics of
the species that transport along the surface, and by coupling it to that of the
surface height proper. In this we follow recent proposals inspired by
``hydrodynamic'' descriptions of pattern formation in aeolian sand dunes and
ion-sputtered systems. From this enlarged model, and by exploiting the
time-scale separation among various dynamical processes in the system, we
derive a single height equation in which coefficients can be related to
experimental parameters. This equation generalizes those obtained by previous
continuum models and is able to account for many experimental features of
pattern formation by IBS at oblique incidence, such as the evolution of the
irradiation-induced amorphous layer, transverse ripple motion with non-uniform
velocity, ripple coarsening, onset of kinetic roughening and other.
Additionally, the dynamics of the full two-field model is compared with that of
the effective interface equation.Comment: 23 pages, 14 figures. Movies of figures 6, 7, and 8 available at
http://gisc.uc3m.es/~javier/Movies
Solid flow drives surface nanopatterning by ion-beam irradiation
Ion Beam Sputtering (IBS) is known to produce surface nanopatterns over
macroscopic areas on a wide range of materials. However, in spite of the
technological potential of this route to nanostructuring, the physical process
by which these surfaces self-organize remains poorly under- stood. We have
performed detailed experiments of IBS on Si substrates that validate dynamical
and morphological predictions from a hydrodynamic description of the
phenomenon. Our results elucidate flow of a nanoscopically thin and highly
viscous surface layer, driven by the stress created by the ion-beam, as a
description of the system. This type of slow relaxation is akin to flow of
macroscopic solids like glaciers or lead pipes, that is driven by defect
dynamics.Comment: 12 pages, 4 figure
The impact of the Kasatochi eruption on the Moon's illumination during the August 2008 lunar eclipse
The Moon's changeable aspect during a lunar eclipse is largely attributable
to variations in the refracted unscattered sunlight absorbed by the terrestrial
atmosphere that occur as the satellite crosses the Earth's shadow. The
contribution to the Moon's aspect from sunlight scattered at the Earth's
terminator is generally deemed minor. However, our analysis of a published
spectrum of the 16 August 2008 lunar eclipse shows that diffuse sunlight is a
major component of the measured spectrum at wavelengths shorter than 600 nm.
The conclusion is supported by two distinct features, namely the spectrum's
tail at short wavelengths and the unequal absorption by an oxygen collisional
complex at two nearby bands. Our findings are consistent with the presence of
the volcanic cloud reported at high northern latitudes following the 7-8 August
2008 eruption in Alaska of the Kasatochi volcano. The cloud both attenuates the
unscattered sunlight and enhances moderately the scattered component, thus
modifying the contrast between the two contributions.Comment: Accepted for publication in Geophysical Research Letter
Energetic particle acceleration and transport by Alfven/acoustic waves in tokamak-like Solar flares
Alfv´en/acoustic waves are ubiquitous in astrophysical as well as in laboratory plasmas. Their interplay with energetic ions is of crucial importance to understanding the energy
and particle exchange in astrophysical plasmas as well as to obtaining a viable energy source
in magnetically confined fusion devices. In magnetically confined fusion plasmas, an experimental phase-space characterisation of convective and diffusive energetic particle losses induced by Alfv´en/acoustic waves allows for a better understanding of the underlying physics. The relevance of these results in the problem of the anomalous heating of the solar corona is checked by MHD simulations of Tokamak-like Solar flare tubes
- …