Some new additions to the hepatic flora (Jungermanniophyta) for the State of Bahia, Brazil

In this paper are recorded 18 taxa of hepatics (Jungermanniophyta) for the first time for the state of Bahia, Brazil. Of these, Harpalejeunea ovata (Hook.) Schiffn. is new for Brazil. Morphological characters, notes on habitat and substrate are given for each species. Illustrations for Harpalejeunea ovata, Pycnolejeunea callosa (Lindenb.) Steph., Pycnolejeunea macroloba (Nees & Mont.) Schiffn., Rectolejeunea berteroana (Gott. ex Steph.) Evans and Trachylejeunea crenata (Mont. & Nees) Schust. are given

Phase-Space Noncommutativity and the Dirac Equation

We consider full phase-space noncommutativity in the Dirac equation, and find that in order to preserve gauge invariance, configuration space noncommutativity must be dropped. The resulting space structure gives rise to a constant magnetic field background and this effect is explicitly seen on the spectrum of the hydrogen atom. Computing this spectrum we find a bound on the momentum noncommutative parameter $\eta$, \sqrt{\eta}\lsim2.26\mu eV/c.Comment: 11 pages. To match version to appear in Physics Letters

Organizational Capital, Learning-by-Doing and Investment Volatility

This paper addresses the issue of plant-level investment volatility in the context of a purely convex model, where fluctuations are driven by technological shocks. The aim is to assess the role of learning-by-doing in reproducing the well-documented non-smooth investment dynamics at the plant-level, instead of relying on typical non-convexities (fixed costs or indivisibilities) used to account for lumpy investment behavior. The concept of organizational capital is essential in the analysis, and it provides the channel through which learning affects production. Our results indicate that learning-by-doing constitutes a potentially important source of investment volatility at the plant-level, and that one should not believe that convex models of investment necessarily deliver smooth dynamics.Organizational Capital, Investment Volatility, Learning-by-Doing

New bounds for Tsallis parameter in a noncommutative phase-space entropic gravity and nonextensive Friedmann equations

In this paper, we have analyzed the nonextensive Tsallis statistical mechanics in the light of Verlinde's formalism. We have obtained, with the aid of a noncommutative phase-space entropic gravity, a new bound for Tsallis nonextensive (NE) parameter (TNP) that is clearly different from the ones present in the current literature. We derived the Friedmann equations in a NE scenario. We also obtained here a relation between the gravitational constant and the TNP.Comment: 15 pages. Final version to appear in Physica

Noncommutative Black Holes and the Singularity Problem

A phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model is considered to study the interior of a Schwarzschild black hole. Due to the divergence of the probability of finding the black hole at the singularity from a canonical noncommutativity, one considers a non-canonical noncommutativity. It is shown that this more involved type of noncommutativity removes the problem of the singularity in a Schwarzschild black hole.Comment: Based on a talk by CB at ERE2010, Granada, Spain, 6th-10th September 201