15,164 research outputs found
On the relation between Phi(1,2) and Phi(1,5) perturbed minimal models
We consider the RSOS S-matrices of the Phi(1,5) perturbed minimal models
which have recently been found in the companion paper [hep-th/9604098]. These
S-matrices have some interesting properties, in particular, unitarity may be
broken in a stronger sense than seen before, while one of the three classes of
Phi(1,5) perturbations (to be described) shares the same Thermodynamic Bethe
Ansatz as a related Phi(1,2) perturbation. We test these new S-matrices by the
standard Truncated Conformal Space method, and further observe that in some
cases the BA equations for two particle energy levels may be continued to
complex rapidity to describe (a) single particle excitations and (b) complex
eigenvalues of the Hamiltonian corresponding to non-unitary S-matrix elements.
We make some comments on identities between characters in the two related
models following from the fact that the two perturbed theories share the same
breather sector.Comment: LaTeX, 23 pages, 12 figures. Substantial revision of introductory
section, new discussion of complex eigenvalues and non-unitary S-matrice
A measurement of the cosmic ray elements C to Fe in the two energy intervals 0.5-2.0 GeV/n and 20-60 GeV/n
The study of the cosmic ray abundances beyond 20 GeV/n provides additional information on the propagation and containment of the cosmic rays in the galaxy. Since the average amount of interstellar material traversed by cosmic rays decreases as its energy increases, the source composition undergoes less distortion in this higher energy region. However, data over a wide energy range is necessary to study propagation parameters. Some measurements of some of the primary cosmic ray abundance ratios at both low (near 2 GeV/n) and high (above 20 GeV/n) energy are given and compared to the predictions of the leaky box mode. In particular, the integrated values (above 23.7 GeV/n) for the more abundant cosmic ray elements in the interval C through Fe and the differential flux for carbon, oxygen, and the Ne, Mg, Si group are presented. Limited statistics prevented the inclusion of the odd Z elements
Prediction of LDEF ionizing radiation environment
The Long Duration Exposure Facility (LDEF) spacecraft flew in a 28.5 deg inclination circular orbit with an altitude in the range from 172 to 258.5 nautical miles. For this orbital altitude and inclination two components contribute most of the penetrating charge particle radiation encountered - the galactic cosmic rays and the geomagnetically trapped Van Allen protons. Where shielding is less than 1.0 g/sq cm geomagnetically trapped electrons make a significant contribution. The 'Vette' models together with the associated magnetic filed models were used to obtain the trapped electron and proton fluences. The mission proton doses were obtained from the fluence using the Burrell proton dose program. For the electron and bremsstrahlung dose we used the Marshall Space Flight Center (MSFC) electron dose program. The predicted doses were in general agreement with those measured with on-board thermoluminescent detector (TLD) dosimeters. The NRL package of programs, Cosmic Ray Effects on MicroElectronics (CREME), was used to calculate the linear energy transfer (LET) spectrum due to galactic cosmic rays (GCR) and trapped protons for comparison with LDEF measurements
Evolutionary Dynamics on Small-Order Graphs
Abstract. We study the stochastic birth-death model for structured finite populations popularized by Lieberman et al. [Lieberman, E., Hauert, C., Nowak, M.A., 2005. Evolutionary dynamics on graphs. Nature 433, 312-316]. We consider all possible connected undirected graphs of orders three through eight. For each graph, using the Monte Carlo Markov Chain simulations, we determine the fixation probability of a mutant introduced at every possible vertex. We show that the fixation probability depends on the vertex and on the graph. A randomly placed mutant has the highest chances of fixation in a star graph, closely followed by star-like graphs. The fixation probability was lowest for regular and almost regular graphs. We also find that within a fixed graph, the fixation probability of a mutant has a negative correlation with the degree of the starting vertex. 1
STEPS - an approach for human mobility modeling
In this paper we introduce Spatio-TEmporal Parametric Stepping (STEPS) - a simple parametric mobility model which can cover a large spectrum of human mobility patterns. STEPS makes abstraction of spatio-temporal preferences in human mobility by using a power law to rule the nodes movement. Nodes in STEPS have preferential attachment to favorite locations where they spend most of their time. Via simulations, we show that STEPS is able, not only to express the peer to peer properties such as inter-ontact/contact time and to reflect accurately realistic routing performance, but also to express the structural properties of the underlying interaction graph such as small-world phenomenon. Moreover, STEPS is easy to implement, exible to configure and also theoretically tractable
Evolution of the social network of scientific collaborations
The co-authorship network of scientists represents a prototype of complex
evolving networks.
By mapping the electronic database containing all relevant journals in
mathematics and neuro-science for an eight-year period (1991-98), we infer the
dynamic and the structural mechanisms that govern the evolution and topology of
this complex system.
First, empirical measurements allow us to uncover the topological measures
that characterize the network at a given moment, as well as the time evolution
of these quantities.
The results indicate that the network is scale-free, and that the network
evolution is governed by preferential attachment, affecting both internal and
external links.
However, in contrast with most model predictions the average degree increases
in time, and the node separation decreases.
Second, we propose a simple model that captures the network's time evolution.
Third, numerical simulations are used to uncover the behavior of quantities
that could not be predicted analytically.Comment: 14 pages, 15 figure
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Corrigendum: a decision framework for considering climate change adaptation in biodiversity conservation planning
Recovery of Large Angular Scale CMB Polarization for Instruments Employing Variable-delay Polarization Modulators
Variable-delay Polarization Modulators (VPMs) are currently being implemented
in experiments designed to measure the polarization of the cosmic microwave
background on large angular scales because of their capability for providing
rapid, front-end polarization modulation and control over systematic errors.
Despite the advantages provided by the VPM, it is important to identify and
mitigate any time-varying effects that leak into the synchronously modulated
component of the signal. In this paper, the effect of emission from a K
VPM on the system performance is considered and addressed. Though instrument
design can greatly reduce the influence of modulated VPM emission, some
residual modulated signal is expected. VPM emission is treated in the presence
of rotational misalignments and temperature variation. Simulations of
time-ordered data are used to evaluate the effect of these residual errors on
the power spectrum. The analysis and modeling in this paper guides
experimentalists on the critical aspects of observations using VPMs as
front-end modulators. By implementing the characterizations and controls as
described, front-end VPM modulation can be very powerful for mitigating
noise in large angular scale polarimetric surveys. None of the systematic
errors studied fundamentally limit the detection and characterization of
B-modes on large scales for a tensor-to-scalar ratio of . Indeed,
is achievable with commensurately improved characterizations and
controls.Comment: 13 pages, 13 figures, 1 table, matches published versio
Social games in a social network
We study an evolutionary version of the Prisoner's Dilemma game, played by
agents placed in a small-world network. Agents are able to change their
strategy, imitating that of the most successful neighbor. We observe that
different topologies, ranging from regular lattices to random graphs, produce a
variety of emergent behaviors. This is a contribution towards the study of
social phenomena and transitions governed by the topology of the community
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