Spread of Infectious Diseases with a Latent Period

Infectious diseases spread through human networks. Susceptible-Infected-Removed (SIR) model is one of the epidemic models to describe infection dynamics on a complex network connecting individuals. In the metapopulation SIR model, each node represents a population (group) which has many individuals. In this paper, we propose a modified metapopulation SIR model in which a latent period is taken into account. We call it SIIR model. We divide the infection period into two stages: an infected stage, which is the same as the previous model, and a seriously ill stage, in which individuals are infected and cannot move to the other populations. The two infectious stages in our modified metapopulation SIR model produce a discontinuous final size distribution. Individuals in the infected stage spread the disease like individuals in the seriously ill stage and never recover directly, which makes an effective recovery rate smaller than the given recovery rate.Comment: 6 pages, 3 figure

Griffiths Effects in Random Heisenberg Antiferromagnetic S=1 Chains

I consider the effects of enforced dimerization on random Heisenberg antiferromagnetic S=1 chains. I argue for the existence of novel Griffiths phases characterized by {\em two independent dynamical exponents} that vary continuously in these phases; one of the exponents controls the density of spin-1/2 degrees of freedom in the low-energy effective Hamiltonian, while the other controls the corresponding density of spin-1 degrees of freedom. Moreover, in one of these Griffiths phases, the system has very different low temperature behavior in two different parts of the phase which are separated from each other by a sharply defined crossover line; on one side of this crossover line, the system `looks' like a S=1 chain at low energies, while on the other side, it is best thought of as a $S=1/2$ chain. A strong-disorder RG analysis makes it possible to analytically obtain detailed information about the low temperature behavior of physical observables such as the susceptibility and the specific heat, as well as identify an experimentally accessible signature of this novel crossover.Comment: 16 pages, two-column PRB format; 5 figure

Similarity Analysis of Nonlinear Equations and Bases of Finite Wavelength Solitons

We introduce a generalized similarity analysis which grants a qualitative description of the localised solutions of any nonlinear differential equation. This procedure provides relations between amplitude, width, and velocity of the solutions, and it is shown to be useful in analysing nonlinear structures like solitons, dublets, triplets, compact supported solitons and other patterns. We also introduce kink-antikink compact solutions for a nonlinear-nonlinear dispersion equation, and we construct a basis of finite wavelength functions having self-similar properties.Comment: 18 pages Latex, 6 figures ep

Global unions: chasing the dream or building the reality?

This article takes as its theme the global restructuring of capital and its impact on worker organization. It argues for a reassertion of class in any analysis of global solidarity, and assesses the opportunities and barriers to effective global unionization. Rooted in the UK experience, the article analyzes the impact of the European social dimension on trade unions, before taking the discussion into a global dimension. It concludes by suggesting that there are reasons for cautious optimism in terms of solidarity building, despite difficult historical legacies and the common replacement of action with rhetoric

Building a Socio-technical Perspective of Community Resilience with a Semiotic Approach

Situated in the diversity and adversity of real-life contexts facing crisis situations, this research aims at boosting the resilience process within communities supported by digital and social technology. In this paper, eight community leaders in different parts of the world are invited to express their issues and wishes regarding the support of technology to face social challenges. Methods and artefacts based on the Organisational Semiotics (OS) and the Socially-Aware computing have been applied to analyse and consolidate this data. By providing both a systemic view of the problem and also leading to the identification of requirements, the analysis evidences some benefits of the OS-based approach to consolidate perspectives from different real-life scenarios towards building a socio-technical solution

Percolation Transition in the random antiferromagnetic spin-1 chain

We give a physical description in terms of percolation theory of the phase transition that occurs when the disorder increases in the random antiferromagnetic spin-1 chain between a gapless phase with topological order and a random singlet phase. We study the statistical properties of the percolation clusters by numerical simulations, and we compute exact exponents characterizing the transition by a real-space renormalization group calculation.Comment: 9 pages, 4 encapsulated Postscript figures, REVTeX 3.

GEM Operation in Negative Ion Drift Gas Mixtures

The first operation of GEM gas gain elements in negative ion gas mixtures is reported. Gains up to several thousand were obtained from single-stage GEMs in carbon disulfide vapor at low pressure, and in mixtures of carbon disulfide with Argon and Helium, some near 1 bar total pressure.Comment: 7 pages, 3 figure

Randomness-driven quantum phase transition in bond-alternating Haldane chain

The effect of bond randomness on the spin-gapped ground state of the spin-1 bond-alternating antiferromagnetic Heisenberg chain is discussed. By using the loop cluster quantum Monte Carlo method, we investigate the stability of topological order in terms of the recently proposed twist order parameter [M. Nakamura and S. Todo: Phys. Rev. Lett. 89 (2002) 077204]. It is observed that the dimer phases as well as the Haldane phase of the spin-1 Heisenberg chain are robust against a weak randomness, though the valence-bond-solid-like topological order in the latter phase is destroyed by introducing a disorder stronger than the critical value.Comment: 4 pages, 5 figures; minor changes; accepted for publication in J. Phys. Soc. Jp