7,360 research outputs found
Factorial Moments of Continuous Order
The normalized factorial moments are continued to noninteger values of
the order , satisfying the condition that the statistical fluctuations
remain filtered out. That is, for Poisson distribution for all .
The continuation procedure is designed with phenomenology and data analysis in
mind. Examples are given to show how can be obtained for positive and
negative values of . With being continuous, multifractal analysis is
made possible for multiplicity distributions that arise from self-similar
dynamics. A step-by-step procedure of the method is summarized in the
conclusion.Comment: 15 pages + 9 figures (figures available upon request), Late
Large collective Lamb shift of two distant superconducting artificial atoms
Virtual photons can mediate interaction between atoms, resulting in an energy
shift known as a collective Lamb shift. Observing the collective Lamb shift is
challenging, since it can be obscured by radiative decay and direct atom-atom
interactions. Here, we place two superconducting qubits in a transmission line
terminated by a mirror, which suppresses decay. We measure a collective Lamb
shift reaching 0.8% of the qubit transition frequency and exceeding the
transition linewidth. We also show that the qubits can interact via the
transmission line even if one of them does not decay into it.Comment: 7+5 pages, 4+2 figure
Capacity Analysis of MIMO-WLAN Systems with Single Co-Channel Interference
[[abstract]]In this paper, channel capacity of multiple-input multiple-output wireless local area network (MIMO-WLAN) systems with single co-channel interference (CCI) is calculated. A ray-tracing approach is used to calculate the channel frequency response, which is further used to calculate the corresponding channel capacity. The ability to combat CCI for the MIMO-WLAN simple uniform linear array (ULA) and polarization diversity array (PDA) are investigated. Also the effects caused by two antenna arrays for desired system and CCI are quantified. Numerical results show that MIMO-PDA is better than those of MIMO-ULA when interference is present.[[notice]]èŁæŁćźçą[[incitationindex]]EI[[booktype]]çŽæŹ[[booktype]]é»ć
A performance comparison of the contiguous allocation strategies in 3D mesh connected multicomputers
The performance of contiguous allocation strategies can be significantly affected by the distribution of job execution times. In this paper, the performance of the existing contiguous allocation strategies for 3D mesh multicomputers is re-visited in the context of heavy-tailed distributions (e.g., a Bounded Pareto distribution). The strategies are evaluated and compared using simulation experiments for both First-Come-First-Served (FCFS) and Shortest-Service-Demand (SSD) scheduling strategies under a variety of system loads and system sizes. The results show that the performance of the allocation strategies degrades considerably when job execution times follow a heavy-tailed distribution. Moreover, SSD copes much better than FCFS scheduling strategy in the presence of heavy-tailed job execution times. The results also show that the strategies that depend on a list of allocated sub-meshes for both allocation and deallocation have lower allocation overhead and deliver good system performance in terms of average turnaround time and mean system utilization
Hot Topics in Ultra-Peripheral Collisions
Ultra-peripheral collisions of relativistic heavy ions involve long-ranged
electromagnetic interactions at impact parameters too large for hadronic
interactions to occur. The nuclear charges are large; with the coherent
enhancement, the cross sections are also large. Many types of photonuclear and
purely electromagnetic interactions are possible. We present here an
introduction to ultra-peripheral collisions, and present four of the most
compelling physics topics. This note developed from a discussion at a workshop
on ``Electromagnetic Probes of Fundamental Physics,'' in Erice, Italy, Oct.
16-21, 2001.Comment: 7 pages, with 3 figures. This developed from a discussion at the
workshop on "Electromagnetic Probes of Fundamental Physics," Oct. 16-21,
Erice, Ital
Stability of Solid State Reaction Fronts
We analyze the stability of a planar solid-solid interface at which a
chemical reaction occurs. Examples include oxidation, nitridation, or silicide
formation. Using a continuum model, including a general formula for the
stress-dependence of the reaction rate, we show that stress effects can render
a planar interface dynamically unstable with respect to perturbations of
intermediate wavelength
Vector, Axial, Tensor and Pseudoscalar Vacuum Susceptibilities
Using a recently developed three-point formalism within the method of QCD Sum
Rules we determine the vacuum susceptibilities needed in the two-point
formalism for the coupling of axial, vector, tensor and pseudoscalar currents
to hadrons. All susceptibilities are determined by the space-time scale of
condensates, which is estimated from data for deep inelastic scattering on
nucleons
Asymptotic statistics of the n-sided planar Poisson-Voronoi cell. I. Exact results
We achieve a detailed understanding of the -sided planar Poisson-Voronoi
cell in the limit of large . Let be the probability for a cell to
have sides. We construct the asymptotic expansion of up to
terms that vanish as . We obtain the statistics of the lengths of
the perimeter segments and of the angles between adjoining segments: to leading
order as , and after appropriate scaling, these become independent
random variables whose laws we determine; and to next order in they have
nontrivial long range correlations whose expressions we provide. The -sided
cell tends towards a circle of radius (n/4\pi\lambda)^{\half}, where
is the cell density; hence Lewis' law for the average area of
the -sided cell behaves as with . For
the cell perimeter, expressed as a function of the polar
angle , satisfies , where is known Gaussian
noise; we deduce from it the probability law for the perimeter's long
wavelength deviations from circularity. Many other quantities related to the
asymptotic cell shape become accessible to calculation.Comment: 54 pages, 3 figure
Environment-Induced Changes in Selective Constraints on Social Learning During the Peopling of the Americas
The weaponry technology associated with Clovis and related Early Paleoindians represents the earliest well-defined evidence of humans in Pleistocene North America. We assess the technological diversity of these fluted stone points found at archaeological sites in the western and eastern halves of North America by employing statistical tools used in the quantification of ecological biodiversity. Our results demonstrate that the earliest hunters in the environmentally heterogeneous East used a more diverse set of points than those in the environmentally homogenous West. This and other evidence shows that environmental heterogeneity in the East promoted the relaxation of selective constraints on social learning and increased experimentation with point designs
Quantum damping of position due to energy measurements
Quantum theory for measurements of energy is introduced and its consequences
for the average position of monitored dynamical systems are analyzed. It turns
out that energy measurements lead to a localization of the expectation values
of other observables. This is manifested, in the case of position, as a damping
of the motion without classical analogue. Quantum damping of position for an
atom bouncing on a reflecting surface in presence of a homogeneous
gravitational field is dealt in detail and the connection with an experiment
already performed in the classical regime is studied. We show that quantum
damping is testable provided that the same measurement strength obtained in the
experimental verification of the quantum Zeno effect in atomic spectroscopy [W.
M. Itano et al., Phys. Rev. A {\bf 41}, 2295 (1990)] is made available.Comment: 19 pages + 4 figures available upon request; Plain REVTeX; To be
published in Phys. Rev.
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