Periodic Planar Disk Packings

Several conditions are given when a packing of equal disks in a torus is locally maximally dense, where the torus is defined as the quotient of the plane by a two-dimensional lattice. Conjectures are presented that claim that the density of any strictly jammed packings, whose graph does not consist of all triangles and the torus lattice is the standard triangular lattice, is at most $\frac{n}{n+1}\frac{\pi}{\sqrt{12}}$, where $n$ is the number of packing disks. Several classes of collectively jammed packings are presented where the conjecture holds.Comment: 26 pages, 13 figure

The comparative biology of ethanol consumption: An introduction to the symposium

In classical Greek, the word “symposium” signifies a drinking party held for the purposes of intellectual discussion. This symposium introduces a new evolutionary perspective on an ancient question: why are many animals, including humans, attracted to ethanol? Recent research has shown that behavioral responses to ethanol and molecular pathways of inebriation are shared among many taxa (Wolf and Heberlein, 2003), and that the preferences of modern humans for alcohol consumption may derive from the diets of our fruit-eating ancestors (i.e., alcoholism as evolutionary hangover; Dudley, 2000, 2002). Placement of ethanol consumption within historical and comparative contexts may thus yield insight into contemporary patterns of human consumption and excessive use

Negative-frequency modes in quantum field theory

We consider a departure from standard quantum field theory, constructed so as to permit momentum eigenstates of both positive and negative energy. The resulting theory is intriguing because it brings about the cancellation of leading ultra-violet divergences and the absence of a zero-point energy. The theory gives rise to tree-level source-to-source transition amplitudes that are manifestly causal and consistent with standard S-matrix elements. It also leads to the usual result for the oblique corrections to the standard electroweak theory. Remarkably, the latter agreement relies on the breakdown of naive perturbation theory due to resonance effects. It remains to be shown that there are no problems with perturbative unitarity.Comment: 15 pages. Prepared for the proceedings of DISCRETE2014: the Fourth Symposium on Prospects in the Physics of Discrete Symmetries, King's College London, to appear in the Journal of Physics: Conference Series (JPCS). Presented by P. Millingto

The Raman Spectrum of Gypsum

In an investigation of the Raman spectra of some ionized substances in aqueous solution, it was found [1] that the frequency shift given by a solution of potassium carbonate was in fairly close agreement with the strongest shift given by calcite. Data for such a comparison in other cases do not appear to exist, for change of frequency on scattering has been measured for only a few crystalline substances. In addition to calcite [2,3,5], these are quartz [2,3,4,5], ice [5], and topaz [6]. No modified frequencies were found in the light scattered by halite [2], NaCl, fluorite [5], CaF2, or by the salts [7] LiF and NaF. In the present paper are described the results of measurements on gypsum, CaSO4•2H20, and a comparison of these with data on ammonium sulfate solution

Cognitive Dissonance, Pessimism, and Behavioral Spillover Effects

This paper reports results from a unique two-stage experiment designed to examine the spillover effects of optimism and pessimism. In stage 1, we induce optimism or pessimism onto subjects by randomly assigning a high or low piece rate for performing a cognitive task. We find that participants receiving the low piece rate are significantly more pessimistic with respect to performance on this task. In stage 2 individuals participate in an ultimatum game. We find that minimum acceptable offers are significantly lower for pessimistic subjects, though this pessimism was generated in a completely unrelated environment. These results highlight the existence of important spillover effects that can be behaviorally and economically important - for example, pessimism regarding one’s initial conditions (e.g., living in poverty) may have spillover effects on one’s future labor market outcomes.

Welcome to Carbon Balance and Management

We are pleased to announce the launch of Carbon Balance and Management, a new online open access journal published by BioMed Central

Fun Ship Marketing Philosophy

The President of Carnival Cruise Lines discusses his company\u27s philosophy and operations as they relate to the Fun Ship cruise experience. Carnival, the world\u27s largest cruise line, is positioned as a model in the business