The evolution of cooperation is a fundamental problem in evolutionary biology. Over the last decades a wealth of models and mechanisms have been proposed for explaining how cooperators can thrive under Darwinian selection. At the same time, discussions of the conceptual connections between the different approaches have often been neglected. The synthesis proposed by Lehmann & Keller (2006) is t...

s It is suggested that simple electronic shielding effects induced by wave function antisymmetrization tend to govern the energy ordering of singlet and triplet terms within a two-electron atomic configuration. This approach gives rise to the following alternating rule: For the term of greatest orbital angular momentum within a configuration, the triplet lies below the singlet. The energy order...

In this article we formulate and discuss one particle quantum scattering theory on an arbitrary finite graph with n open ends and where we define the Hamiltonian to be (minus) the Laplace operator with general boundary conditions at the vertices. This results in a scattering theory with n channels. The corresponding on-shell S-matrix formed by the reflection and transmission amplitudes for inco...

In this issue of the Biophysical Journal, Jarecki et al. (1) investigate the possibility of combining two strategies commonly used to measure distances between loci in a number of systems. The first strategy, Förster resonance energy transfer (FRET), is a spectroscopic method based on energy transfer between two fluorescent molecules: upon transferring its excitation energy to an acceptor via a...

Quotients of derivatives of continuously differentiable functions of the single variable are characterized without using differentiation. This yields augmentations of L’Hôpital’s rule, for an indeterminate form of type 0/0, and reformulations of the theorem of Lagrange. AMS subject classifications: 26A24, 49K05, 90C30, 90C32