6,822 research outputs found
The 30/20 GHZ net market assessment
By creating a number of market scenarios variations dealing with network types, network sizes, and service price levels were analyzed for their impact on market demand. Each market scenario represents a market demand forecast with results for voice, data, and video service traffic expressed in peak load megabits per second
Infinite compressibility states in the Hierarchical Reference Theory of fluids. II. Numerical evidence
Continuing our investigation into the Hierarchical Reference Theory of fluids
for thermodynamic states of infinite isothermal compressibility kappa[T] we now
turn to the available numerical evidence to elucidate the character of the
partial differential equation: Of the three scenarios identified previously,
only the assumption of the equations turning stiff when building up the
divergence of kappa[T] allows for a satisfactory interpretation of the data. In
addition to the asymptotic regime where the arguments of part I
(cond-mat/0308467) directly apply, a similar mechanism is identified that gives
rise to transient stiffness at intermediate cutoff for low enough temperature.
Heuristic arguments point to a connection between the form of the Fourier
transform of the perturbational part of the interaction potential and the
cutoff where finite difference approximations of the differential equation
cease to be applicable, and they highlight the rather special standing of the
hard-core Yukawa potential as regards the severity of the computational
difficulties.Comment: J. Stat. Phys., in press. Minor changes to match published versio
Nonparametric Bayesian grouping methods for spatial time-series data
We describe an approach for identifying groups of dynamically similar
locations in spatial time-series data based on a simple Markov transition
model. We give maximum-likelihood, empirical Bayes, and fully Bayesian
formulations of the model, and describe exhaustive, greedy, and MCMC-based
inference methods. The approach has been employed successfully in several
studies to reveal meaningful relationships between environmental patterns and
disease dynamics.Comment: 11 pages, no figure
Estimating bear habitat quality in southeastern British Columbia by measuring changes in bear body condition
Comparisons of global topographic/isostatic models to the Earth's observed gravity field
The Earth's gravitational potential, as described by a spherical harmonic expansion to degree 180, was compared to the potential implied by the topography and its isostatic compensation using five different hypothesis. Initially, series expressions for the Airy/Heiskanen topographic isostatic model were developed to the third order in terms of (h/R), where h is equivalent rock topography and R is a mean Earth radius. Using actual topographic developments for the Earth, it was found that the second and third terms of the expansion contributed 30 and 3 percents, of the first of the expansion. With these new equations it is possible to compute depths (D) of compensation, by degree, using 3 different criteria. The results show that the average depth implied by criterion I is 60 km while it is about 33 km for criteria 2 and 3 with smaller compensation depths at the higher degrees. Another model examined was related to the Vening-Meinesz regional hypothesis implemented in the spectral domain. Finally, oceanic and continental response functions were derived for the global data sets and comparisons made to locally determined values
On principal hook length partitions and durfee sizes in skew characters
In this paper we construct for a given arbitrary skew diagram A all
partitions nu with maximal principal hook lengths among all partitions with the
character [nu] appearing in the skew character [A]. Furthermore we show that
these are also partitions with minimal Durfee size. This we use to give the
maximal Durfee size for [nu] appearing in [A] for the cases when A decays into
two partitions and for some special cases of A. Also this gives conditions for
two skew diagrams to represent the same skew character.Comment: 13 pages, minor changes from v1 to v2 as suggested by the referee, to
appear in Annals. Com
Detection and imaging of the oxygen deficiency in single crystalline YBaCuO thin films using a positron beam
Single crystalline YBaCuO
(YBCO) thin films were grown by pulsed laser deposition (PLD) in order to probe
the oxygen deficiency using a mono-energetic positron beam. The sample
set covered a large range of (0.191<<0.791) yielding a
variation of the critical temperature between 25 and 90\,K. We
found a linear correlation between the Doppler broadening of the positron
electron annihilation line and determined by X-ray diffraction (XRD).
Both, the origin of the found correlation and the influence of metallic
vacancies, were examined with the aid of ab-initio calculations that allowed us
(i) to exclude the presence of Y vacancies and (ii) to ensure that positrons
still probe despite the potential presence of Ba or Cu vacancies. In
addition, by scanning with the positron beam the spatial variation of
could be analyzed. It was found to fluctuate with a standard deviation of up to
within a single YBCO film
Uniaxial magnetocrystalline anisotropy in
is a paramagnetic metal and since its low temperature
resistivity is described by with , it
is also considered a non-Fermi liquid (NFL) metal. We have performed extensive
magnetoresistance and Hall effect measurements of untwinned epitaxial films of
. These measurements reveal that exhibits
uniaxial magnetocrystalline anisotropy. In addition, the low-temperature NFL
behavior is most effectively suppressed when a magnetic field is applied along
the easy axis, suggesting that critical spin fluctuations, possibly due to
proximity of a quantum critical phase transition, are related to the NFL
behavior.Comment: 7 figure
Possible indicators for low dimensional superconductivity in the quasi-1D carbide Sc3CoC4
The transition metal carbide Sc3CoC4 consists of a quasi-one-dimensional (1D)
structure with [CoC4]_{\inft} polyanionic chains embedded in a scandium
matrix. At ambient temperatures Sc3CoC4 displays metallic behavior. At lower
temperatures, however, charge density wave formation has been observed around
143K which is followed by a structural phase transition at 72K. Below T^onset_c
= 4.5K the polycrystalline sample becomes superconductive. From Hc1(0) and
Hc2(0) values we could estimate the London penetration depth ({\lambda}_L ~=
9750 Angstroem) and the Ginsburg-Landau (GL) coherence length ({\xi}_GL ~= 187
Angstroem). The resulting GL-parameter ({\kappa} ~= 52) classifies Sc3CoC4 as a
type II superconductor. Here we compare the puzzling superconducting features
of Sc3CoC4, such as the unusual temperature dependence i) of the specific heat
anomaly and ii) of the upper critical field H_c2(T) at T_c, and iii) the
magnetic hysteresis curve, with various related low dimensional
superconductors: e.g., the quasi-1D superconductor (SN)_x or the 2D
transition-metal dichalcogenides. Our results identify Sc3CoC4 as a new
candidate for a quasi-1D superconductor.Comment: 4 pages, 5 figure
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