79,802 research outputs found
Fractal Location and Anomalous Diffusion Dynamics for Oil Wells from the KY Geological Survey
Utilizing data available from the Kentucky Geonet (KYGeonet.ky.gov) the
fossil fuel mining locations created by the Kentucky Geological Survey
geo-locating oil and gas wells are mapped using ESRI ArcGIS in Kentucky single
plain 1602 ft projection. This data was then exported into a spreadsheet
showing latitude and longitude for each point to be used for modeling at
different scales to determine the fractal dimension of the set. Following the
porosity and diffusivity studies of Tarafdar and Roy1 we extract fractal
dimensions of the fossil fuel mining locations and search for evidence of
scaling laws for the set of deposits. The Levy index is used to determine a
match to a statistical mechanically motivated generalized probability function
for the wells. This probability distribution corresponds to a solution of a
dynamical anomalous diffusion equation of fractional order that describes the
Levy paths which can be solved in the diffusion limit by the Fox H function
ansatz.Comment: : 8 pages, 3 figures, AIPG Conference Meeting, Grand Junction CO,
Oct. 200
Using entanglement to discern phases in the disordered one-dimensional Bose-Hubbard model
We perform a matrix product state based density matrix renormalisation group
analysis of the phases for the disordered one-dimensional Bose-Hubbard model.
For particle densities N/L = 1, 1/2 and 2 we show that it is possible to obtain
a full phase diagram using only the entanglement properties, which come "for
free" when performing an update. We confirm the presence of Mott insulating,
superfluid and Bose glass phases when N/L = 1 and 1/2 (without the Mott
insulator) as found in previous studies. For the N/L = 2 system we find a
double lobed superfluid phase with possible reentrance.Comment: 6 pages, 4 figure
Sensing and decision-making in random search
While microscopic organisms can use gradient-based search to locate
resources, this strategy can be poorly suited to the sensory signals available
to macroscopic organisms. We propose a framework that models search-decision
making in cases where sensory signals are infrequent, subject to large
fluctuations, and contain little directional information. Our approach
simultaneously models an organism's intrinsic movement behavior (e.g. Levy
walk) while allowing this behavior to be adjusted based on sensory data. We
find that including even a simple model for signal response can dominate other
features of random search and greatly improve search performance. In
particular, we show that a lack of signal is not a lack of information.
Searchers that receive no signal can quickly abandon target-poor regions. Such
phenomena naturally give rise to the area-restricted search behavior exhibited
by many searching organisms
Numerical study of the derivative of the Riemann zeta function at zeros
The derivative of the Riemann zeta function was computed numerically on
several large sets of zeros at large heights. Comparisons to known and
conjectured asymptotics are presented.Comment: 13 pages, 5 figures; minor typos fixe
Exhumation history of eastern Ladakh revealed by Ar-40/Ar-39 and fission-track ages: the Indus River-Tso Morari transect, NW Himalaya
Fission-track and Ar-40/Ar-39 ages place time constraints on the exhumation of the North Himalayan nappe stack, the Indus Suture Zone and Molasse, and the Transhimalayan Batholith in eastern Ladakh (NW India). Results from this and previous studies on a north-south transect passing near Tso Morari Lake suggest that the SW-directed North Himalayan nappe stack (comprising the Mata, Tetraogal and Tso Morari nappes) was emplaced and metamorphosed by c. 50-45 Ma, and exhumed to moderately shallow depths (c. 10 km) by c. 45-40 Ma. From the mid-Eocene to the present, exhumation continued at a steady and slow rate except for the root zone of the Tso Morari nappe, which cooled faster than the rest of the nappe stack. Rapid cooling occurred at c. 20 Ma and is linked to brittle deformation along the normal Ribil-Zildat Fault concomitant with extrusion of the Crystalline nappe in the south. Data from the Indus Molasse suggest that sediments were still being deposited during the Miocene
The zeta function on the critical line: Numerical evidence for moments and random matrix theory models
Results of extensive computations of moments of the Riemann zeta function on
the critical line are presented. Calculated values are compared with
predictions motivated by random matrix theory. The results can help in deciding
between those and competing predictions. It is shown that for high moments and
at large heights, the variability of moment values over adjacent intervals is
substantial, even when those intervals are long, as long as a block containing
10^9 zeros near zero number 10^23. More than anything else, the variability
illustrates the limits of what one can learn about the zeta function from
numerical evidence.
It is shown the rate of decline of extreme values of the moments is modelled
relatively well by power laws. Also, some long range correlations in the values
of the second moment, as well as asymptotic oscillations in the values of the
shifted fourth moment, are found.
The computations described here relied on several representations of the zeta
function. The numerical comparison of their effectiveness that is presented is
of independent interest, for future large scale computations.Comment: 31 pages, 10 figures, 19 table
Generating the Baryon Asymmetry of the Universe in Split Fermion Models
The origin of the matter-antimatter asymmetry of the universe is one of the
major unsolved problems in cosmology and particle physics. In this paper, we
investigate the recently proposed possibility that split fermion models --
extra dimensional models where the standard model fermions are localized to
different points around the extra dimension -- could provide a means to
generate this asymmetry during the phase transition of the localizing scalars.
After setting up the scenario that we consider, we use a single fermion toy
model to estimate the reflection coefficients for scattering off the phase
boundary using a more realistic scalar profile than previous work resulting in
a different Kaluza Klein spectrum. The value we calculate for is
consistent with the mechanism being the source of the baryon asymmetry of our
universe provided the violating processes have an efficiency of order
.Comment: 17 pages, 3 figures; References added; Minor changes, Accepted for
publication in Phys. Rev.
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