1,394 research outputs found
Power laws of complex systems from Extreme physical information
Many complex systems obey allometric, or power, laws y=Yx^{a}. Here y is the
measured value of some system attribute a, Y is a constant, and x is a
stochastic variable. Remarkably, for many living systems the exponent a is
limited to values +or- n/4, n=0,1,2... Here x is the mass of a randomly
selected creature in the population. These quarter-power laws hold for many
attributes, such as pulse rate (n=-1). Allometry has, in the past, been
theoretically justified on a case-by-case basis. An ultimate goal is to find a
common cause for allometry of all types and for both living and nonliving
systems. The principle I - J = extrem. of Extreme physical information (EPI) is
found to provide such a cause. It describes the flow of Fisher information J =>
I from an attribute value a on the cell level to its exterior observation y.
Data y are formed via a system channel function y = f(x,a), with f(x,a) to be
found. Extremizing the difference I - J through variation of f(x,a) results in
a general allometric law f(x,a)= y = Yx^{a}. Darwinian evolution is presumed to
cause a second extremization of I - J, now with respect to the choice of a. The
solution is a=+or-n/4, n=0,1,2..., defining the particular powers of biological
allometry. Under special circumstances, the model predicts that such biological
systems are controlled by but two distinct intracellular information sources.
These sources are conjectured to be cellular DNA and cellular transmembrane ion
gradient
Fisher's arrow of `time' in cosmological coherent phase space
Fisher's arrow of `time' in a cosmological phase space defined as in quantum
optics (i.e., whose points are coherent states) is introduced as follows.
Assuming that the phase space evolution of the universe starts from an initial
squeezed cosmological state towards a final thermal one, a Fokker-Planck
equation for the time-dependent, cosmological Q phase space probability
distribution can be written down. Next, using some recent results in the
literature, we derive an information arrow of time for the Fisher phase space
cosmological entropy based on the Q function. We also mention the application
of Fisher's arrow of time to stochastic inflation modelsComment: 10 pages, LaTex, Honorable Mention at GRF-199
Multi-Frequency Synthesis of VLBI Images Using a Generalized Maximum Entropy Method
A new multi-frequency synthesis algorithm for reconstructing images from
multi-frequency VLBI data is proposed. The algorithm is based on a generalized
maximum-entropy method, and makes it possible to derive an effective spectral
correction for images over a broad frequency bandwidth, while simultaneously
reconstructing the spectral-index distribution over the source. The results of
numerical simulations demonstrating the capabilities of the algorithm are
presented.Comment: 17 pages, 8 figure
Reconstructing Images from Projections Using the Maximum-Entropy Method. Numerical Simulations of Low-Aspect Astrotomography
The reconstruction of images from a small number of projections using the
maximum-entropy method (MEM) with the Shannon entropy is considered. MEM
provides higher-quality image reconstruction for sources with extended
components than the Hogbom CLEAN method, which is also used in low-aspect
astrotomography. The quality of image reconstruction for sources with mixed
structure containing bright, compact features embedded in a comparatively weak,
extended base can be further improved using a difference-mapping method, which
requires a generalization of MEM for the reconstruction of sign-variable
functions.We draw conclusions based on the results of numerical simulations for
a number of model radio sources with various morphologies.Comment: 11 pages, 9 figure
Reciprocity relations between ordinary temperature and the Frieden-Soffer's Fisher-temperature
Frieden and Soffer conjectured some years ago the existence of a ``Fisher
temperature" T_F that would play, with regards to Fisher's information measure
I, the same role that the ordinary temperature T plays vis-a-vis Shannon's
logarithmic measure. Here we exhibit the existence of reciprocity relations
between T_F and T and provide an interpretation with reference to the meaning
of T_F for the canonical ensemble.Comment: 3 pages, no figure
Delocalization and the semiclassical description of molecular rotation
We discuss phase-space delocalization for the rigid rotator within a
semiclassical context by recourse to the Husimi distributions of both the
linear and the anisotropic instances. Our treatment is based upon the
concomitant Fisher information measures. The pertinent Wehrl entropy is also
investigated in the linear case.Comment: 6 pages, 3 figure
Value of dual testing for identifying tuberculous infection
Setting: A rural community in Chingleput district in Tamil Nadu state in south India.
Objective: To determine the value of dual testing with PPD-S and PPD-B for
identifying subjects with a tuberculous infection.
Design: About 240,000 subjects in rural south India, all of whom were tested
initially with PPD-S and PPD-B, were followed up for 15 years, mainly by total
population survey once in every 212
years. The incidence of culture-positive
tuberculosis was estimated using life-table technique.
Results: Among 17,530 subjects with an intermediate reaction (8–11 mm) to PPD-S
at intake, 285 with an induration to PPD-S exceeding the induration to PPD-B by at
least 2 mm, had a significantly higher incidence of culture-positive tuberculosis than
the remaining (154 and 93 per 100,000), and similarly 481 who had an induration of
o10mm to PPD-B compared to those with X10mm (131 and 93 per 100,000). These
subjects may be regarded as having a tuberculous infection.
Infection with non-tuberculous mycobacteria conferred protection of about 30%
against the development of tuberculosis over a 15-year period.
Conclusion: In subjects with an intermediate reaction (8–11 mm) to PPD-S, dual
testing with PPD-B enabled identification of those with a tuberculous infection. Most
of the reactions were due to non-tuberculous mycobacteria
A Physical Axiomatic Approach to Schrodinger's Equation
The Schrodinger equation for non-relativistic quantum systems is derived from
some classical physics axioms within an ensemble hamiltonian framework. Such an
approach enables one to understand the structure of the equation, in particular
its linearity, in intuitive terms. Furthermore it allows for a physically
motivated and systematic investigation of potential generalisations which are
briefly discussed.Comment: Extended version. 14 page
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