743 research outputs found
Possible thermodynamic structure underlying the laws of Zipf and Benford
We show that the laws of Zipf and Benford, obeyed by scores of numerical data
generated by many and diverse kinds of natural phenomena and human activity are
related to the focal expression of a generalized thermodynamic structure. This
structure is obtained from a deformed type of statistical mechanics that arises
when configurational phase space is incompletely visited in a severe way.
Specifically, the restriction is that the accessible fraction of this space has
fractal properties. The focal expression is an (incomplete) Legendre transform
between two entropy (or Massieu) potentials that when particularized to first
digits leads to a previously existing generalization of Benford's law. The
inverse functional of this expression leads to Zipf's law; but it naturally
includes the bends or tails observed in real data for small and large rank.
Remarkably, we find that the entire problem is analogous to the transition to
chaos via intermittency exhibited by low-dimensional nonlinear maps. Our
results also explain the generic form of the degree distribution of scale-free
networks.Comment: To be published in European Physical Journal
Bipolar molecular outflows driven by hydromagnetic protostellar winds
We demonstrate that magnetically-collimated protostellar winds will sweep
ambient material into thin, radiative, momentum-conserving shells whose
features reproduce those commonly observed in bipolar molecular outflows. We
find the typical position-velocity and mass-velocity relations to occur in
outflows in a wide variety of ambient density distributions, regardless of the
time histories of their driving winds.Comment: 4 pages, 1 figure, submitted to ApJ
Near-Infrared Photometry of the High-Redshift Quasar RDJ030117+002025: Evidence for a Massive Starburst at z=5.5
With a redshift of z=5.5 and an optical blue magnitude M_B ~ -24.2 mag (~4.5
10^12 L_sun), RDJ030117+002025 is the most distant optically faint (M_B > -26
mag) quasar known. MAMBO continuum observations at lambda=1.2 mm (185
micrometer rest-frame) showed that this quasar has a far-IR luminosity
comparable to its optical luminosity. We present near-infrared J- and K-band
photometry obtained with NIRC on the Keck I telescope, tracing the slope of the
rest frame UV spectrum of this quasar. The observed spectral index is close to
the value of alpha_nu ~ -0.44 measured in composite spectra of optically-bright
SDSS quasars. It thus appears that the quasar does not suffer from strong dust
extinction, which further implies that its low rest-frame UV luminosity is due
to an intrinsically-faint AGN. The FIR to optical luminosity ratio is then much
larger than that observed for the more luminous quasars, supporting the
suggestion that the FIR emission is not powered by the AGN but by a massive
starburst.Comment: 6 pages, APJ in pres
Metalheads: the influence of personality and individual differences on preference for heavy metal
Previous studies have reported reliable associations between personality and music preferences, but have tended to rely on cross-genre preferences at the expense of preferences within a single subgenre. We sought to overcome this limitation by examining associations between individual differences and preferences for a specific subgenre of music, namely, contemporary heavy metal. A total of 414 individuals from Britain were presented with clips of 10 tracks of contemporary heavy metal and asked to rate each for liking. Participants also completed measures of the Big Five personality traits, attitudes toward authority, self-esteem, need for uniqueness, and religiosity. A multiple regression showed that stronger composite preference for the heavy metal tracks was associated with higher Openness to Experience, more negative attitudes toward authority, lower self-esteem, greater need for uniqueness, and lower religiosity. In addition, men showed a significantly stronger preference for the tracks than women (d = 0.54). These results are discussed in terms of the psychological needs that contemporary heavy metal fills for some individuals
The thermodynamics of urban population flows
Orderliness, reflected via mathematical laws, is encountered in different
frameworks involving social groups. Here we show that a thermodynamics can be
constructed that macroscopically describes urban population flows. Microscopic
dynamic equations and simulations with random walkers underlie the macroscopic
approach. Our results might be regarded, via suitable analogies, as a step
towards building an explicit social thermodynamics
First Digit Distribution of Hadron Full Width
A phenomenological law, called Benford's law, states that the occurrence of
the first digit, i.e., , of numbers from many real world sources is
not uniformly distributed, but instead favors smaller ones according to a
logarithmic distribution. We investigate, for the first time, the first digit
distribution of the full widths of mesons and baryons in the well defined
science domain of particle physics systematically, and find that they agree
excellently with the Benford distribution. We also discuss several general
properties of Benford's law, i.e., the law is scale-invariant, base-invariant,
and power-invariant. This means that the lifetimes of hadrons follow also
Benford's law.Comment: 8 latex pages, 4 figures, final version in journal publicatio
Atomic carbon at redshift ~2.5
Using the IRAM 30m telescope we detected the lower fine structure line of
neutral carbon towards three high--redshift sources: IRAS FSC10214 (z=2.3),
SMMJ14011+0252 (z=2.5) and H1413+117 (Cloverleaf quasar, z=2.5). SMMJ14011+0252
is the first high--redshift, non--AGN source in which CI has been detected. The
CI(1-0) line from FSC10214 is almost an order of magnitude weaker than
previously claimed, while our detection in the Cloverleaf is in good agreement
with earlier observations. The CI(1-0) linewidths are similar to the CO widths,
indicating that both lines trace similar regions of molecular gas on galactic
scales. Derived CI masses for all three objects are of order few 10^7 solar
masses and the implied CI(1-0)/CO(3-2) line luminosity ratio is about 0.2. This
number is similar to values found in local galaxies. We derive a CI abundance
of 5x10^{-5} which implies significant metal enrichment of the cold molecular
gas at redshifts 2.5 (age of the universe 2.7 Gyr). We conclude that the
physical properties of systems at large lookback times are similar to today's
starburst/AGN environments.Comment: 4 pages, 2 figures; accepted by A&
MaxEnt and dynamical information
The MaxEnt solutions are shown to display a variety of behaviors (beyond the
traditional and customary exponential one) if adequate dynamical information is
inserted into the concomitant entropic-variational principle. In particular, we
show both theoretically and numerically that power laws and power laws with
exponential cut-offs emerge as equilibrium densities in proportional and other
dynamics
Curvature Radiation in Rotating Pulsar Magnetosphere
We consider the curvature emission properties from relativistic particles
streaming along magnetic field lines and co-rotating with pulsar magnetosphere.
The co-rotation affects the trajectories of the particles and hence the
emission properties, especially the polarization. We consider the modification
of the particle velocity and acceleration due to the co-rotation. Curvature
radiation from a single particle is calculated using the approximation of a
circular path to the particle trajectory. Curvature radiation from particles at
a given height actually contains the contributions from particles streaming
along all the nearby field lines around the tangential point, forming the
emission cone of 1/{\gamma}. The polarization patterns from the emission cone
are distorted by the additional rotation, more serious for emission from a
larger height. Net circular polarization can be generated by the density
gradient in the emission cone. For three typical density models in the form of
core, cone and patches, we calculate the polarization profiles for emission
generated at a given height. We find that the circular polarization could have
a single sign or sign reversal, depending on the density gradient along the
rotation phase. The polarization profiles of the total curvature radiation from
the whole open field line region, calculated by adding the emission from all
possible heights, are similar to that from a dominating emission height. The
circular polarization of curvature radiation has sign reversals in the patchy
emission, while it has a single sign for the core emission, and is negligible
for the cone emission.Comment: 13pages,20figure
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