2-matrix versus complex matrix model, integrals over the unitary group as triangular integrals

We prove that the 2-hermitean matrix model and the complex-matrix model obey the same loop equations, and as a byproduct, we find a formula for Itzykzon-Zuber's type integrals over the unitary group. Integrals over U(n) are rewritten as gaussian integrals over triangular matrices and then computed explicitly. That formula is an efficient alternative to the former Shatashvili's formula.Comment: 29 pages, Late

The Asset Market Game

This paper models asset markets as a game where assets pay according to an arbitrary payoff matrix,investors decide on fractions of wealth to allocate to each asset,and prices result from market clearing. The only pure-strategy Nash equilibrium is to split wealth proportionally to the assets´expected returns, which can be interpreted as investing according to the fundamentals. Further, the equilibrium is evolutionarily stable in the sense of Schaffer (1988). We also study the stability properties of the equilibrium in an evolutionary dynamics where wealth flows with higher probability into those strategies that obtain higher realized payoffs.

The Evolutionary Logic of Feeling Small

In a (generalized symmetric aggregative game, payoffs depend only on individual strategy and an aggregate of all strategies. Players behaving as if they were negligible would optimize taking the aggregate as given. We provide evolutionary and dynamic foundations for such behavior when the game satisfies supermodularity conditions. The results obteined are also useful to characterize evolutionarily stable strategies in a finite population.

Effects of Bose-Einstein Condensation on forces among bodies sitting in a boson heat bath

We explore the consequences of Bose-Einstein condensation on two-scalar-exchange mediated forces among bodies that sit in a boson gas. We find that below the condensation temperature the range of the forces becomes infinite while it is finite at temperatures above condensation.Comment: 10 pages, 2 figure

- AN EVOLUTIONARY MODEL OF BERTRAND OLIGOPOLY

We analyze the long-run outcome of markets in which boundedly rational firms with a decreasingreturns to scale technology compete in prices. The behavior of these firms is based on limitation ofsuccess and experimentation. In this framework, we introduce a new approach to model boundedlyrational behavior, based on the idea of behavioral principles, i.e. formal descriptions. Even with thesimplest ones, the result is that the prices announced are a strict refinement of the set of Nashequilibria. With more sophisticated behavioral principles, the long-run outcome corresponds to theconcept of central prices (wich are also Nash equilibria) introduced here. This is a robust andclear-cut prediction wich, under quadratic costs and arbitrary demand, essentially coincides with theWalrasian equilibrium.evolution, mutation, imitation

Tipificació de dos noms Cavanillesians, Galium Fruticescens (Rubiaceae) i Scorzonera pumila (Compositae)

The Cavanillesian names Galium fruticescens and Scorzonera pumila, basionym of Launaea pumila, are lectotypified from original specimens preserved in the Cavanilles herbarium in the Royal Botanic Garden of Madrid (MA).Els noms cavanillesians Galium fruticescens i Scorzonera pumila, basiònim de Launaea pumila, són lectotipificats a partir d’espècimens que pertanyen al material original de l’autor conservat a l’herbari del Reial Jardí Botànic de Madrid (MA)

The Scientific Reach of Multi-Ton Scale Dark Matter Direct Detection Experiments

The next generation of large scale WIMP direct detection experiments have the potential to go beyond the discovery phase and reveal detailed information about both the particle physics and astrophysics of dark matter. We report here on early results arising from the development of a detailed numerical code modeling the proposed DARWIN detector, involving both liquid argon and xenon targets. We incorporate realistic detector physics, particle physics and astrophysical uncertainties and demonstrate to what extent two targets with similar sensitivities can remove various degeneracies and allow a determination of dark matter cross sections and masses while also probing rough aspects of the dark matter phase space distribution. We find that, even assuming dominance of spin-independent scattering, multi-ton scale experiments still have degeneracies that depend sensitively on the dark matter mass, and on the possibility of isospin violation and inelasticity in interactions. We find that these experiments are best able to discriminate dark matter properties for dark matter masses less than around 200 GeV. In addition, and somewhat surprisingly, the use of two targets gives only a small improvement (aside from the advantage of different systematics associated with any claimed signal) in the ability to pin down dark matter parameters when compared with one target of larger exposure.Comment: 23 pages; updated to match PRD versio

Factors affecting sperm recovery rates and survival after centrifugation of equine semen

Conventional centrifugation protocols result in important sperm losses during removal of the supernatant. In this study, the effect of centrifugation force (400 or 900 × g), duration (5 or 10 min), and column height (20 or 40 mL; Experiment 1); sperm concentration (25, 50, and 100 × 10[superscript 6]/mL; Experiment 2), and centrifugation medium (EZ-Mixin CST [Animal Reproduction Systems, Chino, CA, USA], INRA96 [IMV Technologies, Maple Grove, MN, USA], or VMDZ [Partnar Animal Health, Port Huron, MI, USA]; Experiment 3) on sperm recovery and survival after centrifugation and cooling and storage were evaluated. Overall, sperm survival was not affected by the combination of centrifugation protocol and cooling. Total sperm yield was highest after centrifugation for 10 min at 400 × g in 20-mL columns (95.6 ± 5%, mean ± SD) or 900 × g in 20-mL (99.2 ± 0.8%) or 40-mL (91.4 ± 4.5%) columns, and at 900 × g for 5 min in 20-mL columns (93.8 ± 8.9%; P < 0.0001). Total (TMY) and progressively motile sperm yield followed a similar pattern (P < 0.0001). Sperm yields were not significantly different among samples centrifuged at various sperm concentrations. However, centrifugation at 100 × 10[superscript 6]/mL resulted in significantly lower total sperm yield (83.8 ± 10.7%) and TMY (81.7 ± 6.8%) compared with noncentrifuged semen. Centrifugation in VMDZ resulted in significantly lower TMY (69.3 ± 22.6%), progressively motile sperm yield (63.5 ± 18.2%), viable yield (60.9 ± 36.5%), and survival of progressively motile sperm after cooling (21 ± 10.8%) compared with noncentrifuged semen. In conclusion, centrifuging volumes of ≤ 20 mL minimized sperm losses with conventional protocols. With 40-mL columns, it may be recommended to increase the centrifugal force to 900 × g for 10 min and dilute the semen to a sperm concentration of 25 to 50 × 10[superscript 6]/mL in a milk- or fractionated milk-based medium. The semen extender VMDZ did not seem well suited for centrifugation of equine semen