The fractional Laplacian operator -(-delta)(alpha/2) appears in a wide class of physical systems, including Lévy flights and stochastic interfaces. In this paper, we provide a discretized version of this operator which is well suited to deal with boundary conditions on a finite interval. The implementation of boundary conditions is justified by appealing to two physical models, namely, hopping ...

The propagation of a pulse in a nonlinear array of oscillators is influenced by the nature of the array and by its coupling to a thermal environment. For example, in some arrays a pulse can be speeded up while in others a pulse can be slowed down by raising the temperature. We begin by showing that an energy pulse (one dimension) or energy front (two dimensions) travels more rapidly and remains...

Under 5 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 6.4 5 to 9 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 6.6 10 to 14 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 7.1 15 to 19 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 7.5 20 to 24 years . . . . . . . . . . . . . . . . . . . . ....

This study describes the risk network structure of persons with HIV infection during its early epidemic phase in Colorado Springs, USA, using analysis of community-wide HIV/AIDS contact tracing records (sexual and injecting drug partners) from 1985 to 1999. Paired partner information from other STD/HIV programme records was used to augment network connections. Analyses were conducted with and w...

Introduction It has been known for quite a while that traditional ethical theories have very counterintuitive and paradoxical implications for questions concerning procreation and our moral duties to future generations. Classical Utilitarianism, for example, seems to imply that we have a moral duty to procreate and that we should try to have as many off-springs as possible. More disturbingly, i...

Investigation of climatic conditions prior to the Sturtian glaciations is critical to understanding the trigger mechanism for the series of Neoproterozoic global glaciations. In this study, we report high-resolution chemical index of alteration (CIA) records in the sediments of South China prior to the Sturtian glaciation (820~720 Ma). Our results showed there occurred multiple climate cooling ...

In a recent paper, Nof et al. (J Paleolimnol 35:417–439, 2006) suggest a physical mechanism which could account for the formation of ice on Lake Kinneret (Sea of Galilee) in northern Israel. Based on the sea surface temperature record of sediment cores from the Mediterranean Sea the authors argue that centennial-scale cold events had the potential to trigger local ‘springs ice’ formation on the...