5,446 research outputs found
Born's rule from measurements of classical signals by threshold detectors which are properly calibrated
The very old problem of the statistical content of quantum mechanics (QM) is
studied in a novel framework. The Born's rule (one of the basic postulates of
QM) is derived from theory of classical random signals. We present a
measurement scheme which transforms continuous signals into discrete clicks and
reproduces the Born's rule. This is the sheme of threshold type detection.
Calibration of detectors plays a crucial role.Comment: The problem of double clicks is resolved; hence, one can proceed in
purely wave framework, i.e., the wave-partcile duality has been resolved in
favor of the wave picture of prequantum realit
Anomalous Transport in Conical Granular Piles
Experiments on 2+1-dimensional piles of elongated particles are performed.
Comparison with previous experiments in 1+1 dimensions shows that the addition
of one extra dimension to the dynamics changes completely the avalanche
properties, appearing a characteristic avalanche size. Nevertheless, the time
single grains need to cross the whole pile varies smoothly between several
orders of magnitude, from a few seconds to more than 100 hours. This behavior
is described by a power-law distribution, signaling the existence of scale
invariance in the transport process.Comment: Accepted in PR
Breakdown of self-organized criticality
We introduce two sandpile models which show the same behavior of real
sandpiles, that is, an almost self-organized critical behavior for small
systems and the dominance of large avalanches as the system size increases. The
systems become fully self-organized critical, with the critical exponents of
the Bak, Tang and Wiesenfeld model, as the system parameters are changed,
showing that these systems can make a bridge between the well known theoretical
and numerical results and what is observed in real experiments. We find that a
simple mechanism determines the boundary where self-organized can or cannot
exist, which is the presence of local chaos.Comment: 3 pages, 4 figure
Silicates in D-type symbiotic stars: an ISO overview
We investigate the IR spectral features of a sample of D-type symbiotic
stars. Analyzing unexploited ISO-SWS data, deriving the basic observational
parameters of dust bands and comparing them with respect to those observed in
other astronomical sources, we try to highlight the effect of environment on
grain chemistry and physic. We find strong amorphous silicate emission bands at
10 micron and 18 micron in a large fraction of the sample. The analysis of the
10 micron band, along with a direct comparison with several astronomical
sources, reveals that silicate dust in symbiotic stars shows features between
the characteristic circumstellar environments and the interstellar medium. This
indicates an increasing reprocessing of grains in relation to specific
symbiotic behavior of the objects. A correlation between the central wavelength
of the 10 and 18 micron dust bands is found. By the modeling of IR spectral
lines we investigate also dust grains conditions within the shocked nebulae.
Both the unusual depletion values and the high sputtering efficiency might be
explained by the formation of SiO moleculae, which are known to be a very
reliable shock tracer. We conclude that the signature of dust chemical
disturbance due to symbiotic activity should be looked for in the outer,
circumbinary, expanding shells where the environmental conditions for grain
processing might be achieved. Symbiotic stars are thus attractive targets for
new mid-infrared and mm observations.Comment: 24 pages, 6 figures, 5 tables - to be published in A
Possible Stratification Mechanism in Granular Mixtures
We propose a mechanism to explain what occurs when a mixture of grains of
different sizes and different shapes (i.e. different repose angles) is poured
into a quasi-two-dimensional cell. Specifically, we develop a model that
displays spontaneous stratification of the large and small grains in
alternating layers. We find that the key requirement for stratification is a
difference in the repose angles of the two pure species, a prediction confirmed
by experimental findings. We also identify a kink mechanism that appears to
describe essential aspects of the dynamics of stratification.Comment: 4 pages, 4 figures, http://polymer.bu.edu/~hmakse/Home.htm
On the complexity of some birational transformations
Using three different approaches, we analyze the complexity of various
birational maps constructed from simple operations (inversions) on square
matrices of arbitrary size. The first approach consists in the study of the
images of lines, and relies mainly on univariate polynomial algebra, the second
approach is a singularity analysis, and the third method is more numerical,
using integer arithmetics. Each method has its own domain of application, but
they give corroborating results, and lead us to a conjecture on the complexity
of a class of maps constructed from matrix inversions
Velocity Fluctuations in Electrostatically Driven Granular Media
We study experimentally the particle velocity fluctuations in an
electrostatically driven dilute granular gas. The experimentally obtained
velocity distribution functions have strong deviations from Maxwellian form in
a wide range of parameters. We have found that the tails of the distribution
functions are consistent with a stretched exponential law with typical
exponents of the order 3/2. Molecular dynamic simulations shows qualitative
agreement with experimental data. Our results suggest that this non-Gaussian
behavior is typical for most inelastic gases with both short and long range
interactions.Comment: 4 pages, 4 figure
The effects of varying colour-luminosity relations on supernova science
The success of Type Ia supernova (SN Ia) distance standardisation for
cosmology relies on a single global linear relationship between their peak
luminosity and colour, the parameter. However, there are several pieces
of evidence and physical reasons to believe that this relation is not universal
and may change within different subgroups, or even among individual objects. In
this work, we allow to vary among subpopulations with different
observed properties in the cosmological fits. Although the inferred
cosmological parameters are consistent with previous studies that assume a
single colour-luminosity relation, we find that the SN data favour nonuniversal
distributions of when split according to SN colour and/or host-galaxy
mass. For galaxy mass, we obtain a -step relation in which low
values occur in more massive galaxies, a trend that can be explained by
differing dust reddening laws for two types of environments. For colour, we
find that bluer/redder SNe Ia are consistent with a lower/larger . This
trend is explained with being a combination of a low intrinsic
colour-luminosity relation dominant in bluer SNe and a higher extrinsic
reddening relation dominant at redder colours. The host galaxy mass-step
correction always provides better distance calibration, regardless of the
multiple approaches, and we suggest that it may come from a difference
in intrinsic colour-luminosity properties of SNe Ia in two types of
environments. Additionally, we find that blue SNe in low-mass environments are
better standard candles than the others.Comment: 11 pages, 7 figures, 2 tables. Accepted in MNRA
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