Variable selection is fundamental to high-dimensional statistical modeling. Many variable selection techniques may be implemented by maximum penalized likelihood using various penalty functions. Optimizing the penalized likelihood function is often challenging because it may be nondifferentiable and/or nonconcave. This article proposes a new class of algorithms for finding a maximizer of the pe...

Nanoporous metal prepared by the corrosion of an alloy can take the form of monolithic, millimeter-sized bodies containing approximately 1015 nanoscale ligaments per cubic millimeter. Applications have been suggested, for instance in catalysis, sensing and actuation. Although the process of dealloying has seen many studies, the underlying processes remain to be clarified in more detail. Here we...

Hybrid quantum mechanics/molecular mechanics (QM/MM) simulations have become a popular tool for investigating chemical reactions in condensed phases. In QM/MM methods, the region of the system in which the chemical process takes place is treated at an appropriate level of quantum chemistry theory, while the remainder is described by a molecular mechanics force field. Within this approach, chemi...

The stability of phases at finite temperatures is given by the free energy. But the fact that it is not expressible in terms of ensemble averages over functions of position and velocity coordinates, complicates its determination in atomistic simulations. In order to overcome this problem, thermodynamic integration methods are used. This method is not limited to thermodynamic paths which can be ...

Combined quantum-mechanics/molecular-mechanics (QM/MM) methods are making rapid progress both methodologically and with respect to their range of application. Mechanistic studies on enzymes, including contributions towards the understanding of enzyme catalysis, continue to be a major target. They are joined by calculations of pK(a) values, redox properties, ground- and excited-state spectroscop...

Within-host competition is an important factor in host-parasite relationships, yet most studies consider interactions involving only single parasite species. We investigated the interaction between a virulent obligate entomopathogenic fungus, Metarhizium anisopliae var. anisopliae, and a normally avirulent, opportunistic fungal pathogen, Aspergillus flavus, in their leaf-cutting ant host, Acrom...