Previous studies have shown that hitchhiking in standard GAs can cause premature convergence. In this study we show that hitchhiking also occurs in adaptive operators, specifically, selective crossover an adaptive recombination operator. We compare selective crossover with uniform crossover (a highly disruptive operator) and show that although selective crossover favours hitchhikers more than u...

Cells possess internal ∼24 hr or circadian clocks that synchronize physiological processes with daily cycles of light and nutrient availability. In this issue, Asher et al. (2010) find that PARP-1 (poly(ADP-ribose) polymerase 1) modifies components of the clock machinery in response to feeding, providing a mechanism for how metabolic rhythms coordinate with circadian rhythms.

Comprehensive semantic descriptions of Web services are essential to exploit them in their full potential, that is, discovering them dynamically, and enabling automated service negotiation, composition and monitoring. The semantic mechanisms currently available in service registries which are based on taxonomies fail to provide the means to achieve this. Although the terms “taxonomy” and “ontol...

Many information systems are reengineered and redeveloped in practice, since they are legacy software. Typically, no requirements and design specifications exist and, therefore, also no traceability information. While especially the long-term utility of such information is well known, an important question in reengineering is whether installing it can have immediate benefits in the course of th...

A foundational background in neuroscience has become a significant component of a wellrounded education in the field of psychology. In fact, in the last decades, progress in both modern psychology and neuroscience led to an increasing overlap between both fields, as evidenced not only by its incorporation in several academic psychology graduate and postgraduate programs but also by the interdis...

The metallocofactor involved in fixing nitrogen is not a rigid scaffold, as was previously thought.

We prove several results on some cardinal invariants of the continuum which are closely related to either the splitting number s or its dual, the reaping number r.

We study collections of identical, connected modules which may relocate relative to each other; such a collection is called a modular metamorphic system (see [CPE], [MKK], [PEC], [RV], [YMK]). While such a system must always remain connected, it is possible for such a system to reconfigure its shape through successive motions of individual modules, either by rotation and sliding (e.g., [MKK]) o...

On the basis of simple statistical mechanical models, the prevailing view of the rings of Saturn is that they are unstable and must therefore have been formed rather recently. In this paper, we argue that the Saturn rings and inner moons are in much more stable orbits than previously thought and, therefore, that they likely formed together as part of the initial formation of the solar system. T...

This communication concerns the structure of the electromagnetic quantum vacuum in a disclinated insulator. It is shown that a nonzero vacuum energy density appears when the rotational symmetry of a continuous insulating elastic medium is broken by a disclination. An explicit expression is given for this Casimir energy density in terms of the parameter describing the disclination. ∗On leave fro...