893 research outputs found
A US Perspective on Innovation Policy: What it Will Take to Regain America's Technological Edge
From its very conception, IIASA's Management and Technology Area has been interested in industrial policy issues. This interest increased after the Innovation Management Task started its work. Several collaborative papers have been written which address the problem of industrial policy in different countries or some industrial branches.
In spite of the fact that this paper by was written two years ago, it is an excellent introduction into the US scene where industrial policy discussions are an important issue. The interesting issue which is raised concerns the longer-term horizon in government and company activities and their implementation. This is particularly relevant to industrial restructuring which challenges most of the industrially developed and developing countries in the years to come. Therefore this paper is very relevant in solving many recent policy issues
Natural selection maximizes Fisher information
In biology, information flows from the environment to the genome by the
process of natural selection. But it has not been clear precisely what sort of
information metric properly describes natural selection. Here, I show that
Fisher information arises as the intrinsic metric of natural selection and
evolutionary dynamics. Maximizing the amount of Fisher information about the
environment captured by the population leads to Fisher's fundamental theorem of
natural selection, the most profound statement about how natural selection
influences evolutionary dynamics. I also show a relation between Fisher
information and Shannon information (entropy) that may help to unify the
correspondence between information and dynamics. Finally, I discuss possible
connections between the fundamental role of Fisher information in statistics,
biology, and other fields of science.Comment: Published version freely available at DOI listed her
Efficient data processing and quantum phenomena: Single-particle systems
We study the relation between the acquisition and analysis of data and
quantum theory using a probabilistic and deterministic model for photon
polarizers. We introduce criteria for efficient processing of data and then use
these criteria to demonstrate that efficient processing of the data contained
in single events is equivalent to the observation that Malus' law holds. A
strictly deterministic process that also yields Malus' law is analyzed in
detail. We present a performance analysis of the probabilistic and
deterministic model of the photon polarizer. The latter is an adaptive
dynamical system that has primitive learning capabilities. This additional
feature has recently been shown to be sufficient to perform event-by-event
simulations of interference phenomena, without using concepts of wave
mechanics. We illustrate this by presenting results for a system of two chained
Mach-Zehnder interferometers, suggesting that systems that perform efficient
data processing and have learning capability are able to exhibit behavior that
is usually attributed to quantum systems only.Comment: http://www.compphys.net/dl
Virial statistical description of non-extensive hierarchical systems
In a first part the scope of classical thermodynamics and statistical
mechanics is discussed in the broader context of formal dynamical systems,
including computer programmes. In this context classical thermodynamics appears
as a particular theory suited to a subset of all dynamical systems. A
statistical mechanics similar to the one derived with the microcanonical
ensemble emerges from dynamical systems provided it contains, 1) a finite
non-integrable part of its phase space which is, 2) ergodic at a satisfactory
degree after a finite time. The integrable part of phase space provides the
constraints that shape the particular system macroscopical properties, and the
chaotic part provides well behaved statistical properties over a relevant
finite time. More generic semi-ergodic systems lead to intermittent behaviour,
thus may be unsuited for a statistical description of steady states. Following
these lines of thought, in a second part non-extensive hierarchical systems
with statistical scale-invariance and power law interactions are explored. Only
the virial constraint, consistent with their microdynamics, is included. No
assumptions of classical thermodynamics are used, in particular extensivity and
local homogeneity. In the limit of a large hierarchical range new constraints
emerge in some conditions that depend on the interaction law range. In
particular for the gravitational case, a velocity-site scaling relation is
derived which is consistant with the ones empirically observed in the fractal
interstellar medium.Comment: Based on the talk given at the Meeting on `Statistical Mechanics of
Non-Extensive Systems', 24-25 Oct 05, Paris. To be published in a Special
Issue of Les Comptes rendus de l'Academie des Sciences. 21 pages; 4 figure
The Effect Of Microscopic Correlations On The Information Geometric Complexity Of Gaussian Statistical Models
We present an analytical computation of the asymptotic temporal behavior of
the information geometric complexity (IGC) of finite-dimensional Gaussian
statistical manifolds in the presence of microcorrelations (correlations
between microvariables). We observe a power law decay of the IGC at a rate
determined by the correlation coefficient. It is found that microcorrelations
lead to the emergence of an asymptotic information geometric compression of the
statistical macrostates explored by the system at a faster rate than that
observed in absence of microcorrelations. This finding uncovers an important
connection between (micro)-correlations and (macro)-complexity in Gaussian
statistical dynamical systems.Comment: 12 pages; article in press, Physica A (2010)
Varying c and Particle Horizons
We explore what restrictions may impose the second law of thermodynamics on
varying speed of light theories. We find that the attractor scenario solving
the flatness problem is consistent with the generalized second law at late
time.Comment: Latex file, 8 pages, to be published in Physics Letters
A first--order irreversible thermodynamic approach to a simple energy converter
Several authors have shown that dissipative thermal cycle models based on
Finite-Time Thermodynamics exhibit loop-shaped curves of power output versus
efficiency, such as it occurs with actual dissipative thermal engines. Within
the context of First-Order Irreversible Thermodynamics (FOIT), in this work we
show that for an energy converter consisting of two coupled fluxes it is also
possible to find loop-shaped curves of both power output and the so-called
ecological function against efficiency. In a previous work Stucki [J.W. Stucki,
Eur. J. Biochem. vol. 109, 269 (1980)] used a FOIT-approach to describe the
modes of thermodynamic performance of oxidative phosphorylation involved in
ATP-synthesis within mithochondrias. In that work the author did not use the
mentioned loop-shaped curves and he proposed that oxidative phosphorylation
operates in a steady state simultaneously at minimum entropy production and
maximum efficiency, by means of a conductance matching condition between
extreme states of zero and infinite conductances respectively. In the present
work we show that all Stucki's results about the oxidative phosphorylation
energetics can be obtained without the so-called conductance matching
condition. On the other hand, we also show that the minimum entropy production
state implies both null power output and efficiency and therefore this state is
not fulfilled by the oxidative phosphorylation performance. Our results suggest
that actual efficiency values of oxidative phosphorylation performance are
better described by a mode of operation consisting in the simultaneous
maximization of the so-called ecological function and the efficiency.Comment: 20 pages, 7 figures, submitted to Phys. Rev.
Computer simulation of Wheeler's delayed choice experiment with photons
We present a computer simulation model of Wheeler's delayed choice experiment
that is a one-to-one copy of an experiment reported recently (V. Jacques {\sl
et al.}, Science 315, 966 (2007)). The model is solely based on experimental
facts, satisfies Einstein's criterion of local causality and does not rely on
any concept of quantum theory. Nevertheless, the simulation model reproduces
the averages as obtained from the quantum theoretical description of Wheeler's
delayed choice experiment. Our results prove that it is possible to give a
particle-only description of Wheeler's delayed choice experiment which
reproduces the averages calculated from quantum theory and which does not defy
common sense.Comment: Europhysics Letters (in press
Field Theory Entropy, the -theorem and the Renormalization Group
We consider entropy and relative entropy in Field theory and establish
relevant monotonicity properties with respect to the couplings. The relative
entropy in a field theory with a hierarchy of renormalization group fixed
points ranks the fixed points, the lowest relative entropy being assigned to
the highest multicritical point. We argue that as a consequence of a
generalized theorem Wilsonian RG flows induce an increase in entropy and
propose the relative entropy as the natural quantity which increases from one
fixed point to another in more than two dimensions.Comment: 25 pages, plain TeX (macros included), 6 ps figures. Addition in
title. Entropy of cutoff Gaussian model modified in section 4 to avoid a
divergence. Therefore, last figure modified. Other minor changes to improve
readability. Version to appear in Phys. Rev.
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