A new Miconia (Melastomatacaeae) from Bolivia, with remarks on angular-branched species in the Andes

A new species of Melastomataceae frorm Bolivia is described, illustrated and placed in a phenetic context within Miconia, a genus of 1000 species and about 2000 published names. Miconia quadrialata is readily distinguished from its Congeners by two-colored leaves and sharply four-angular and winged branchlets. A search for quadrangular-branched miconias revealed that 12 of 15 such species (in four sections), including the new species, occur in cloud forest in the Andes, raising the question of the adaptive significance of quadrangular branchlets

Search for Higgs and New Phenomena at Colliders

The present status of searches for the Higgs boson(s) and new phenomena is reviewed. The focus is on analyses and results from the current runs of the HERA and Tevatron experiments. The LEP experiments have released their final combined MSSM Higgs results for this conference. Also included are results from sensitivity studies of the LHC experiments and lepton flavour violating searches from the B factories, KEKB and PEP-II.Comment: XXII International Symposium on Lepton-Photon Interactions at High Energy (11 pages, 16 figures, 2 tables

Creative destruction and asset prices

This paper introduces Schumpeter's idea of creative destruction into asset pricing. The key point of our model is that small and value firms are more likely destroyed during technological revolutions, resulting into higher expected returns for these stocks. A two-factor model including market return and patent activity growth - the proxy for creative destruction risk - accounts for a large portion of the cross-sectional variation of size and book-to-market sorted portfolios and prices HML and SMB. The expected return difference between assets with the highest and lowest exposure to creative destruction risk amounts to 8.6 percent annually. --creative destruction,asset pricing,size and value premium,patents

Atomic ionization by twisted photons: Angular distribution of emitted electrons

We investigate the angular distribution of electrons that are emitted in the ionization of hydrogen-like ions by twisted photons. Analysis is performed based on the first-order perturbation theory and the non-relativistic Schr\"odinger equation. Special attention is paid to the dependence of the electron emission pattern on the impact parameter b of the ion with respect to the centre of the twisted wave front. In order to explore such a dependence, detailed calculations were carried out for the photoionization of the 1s ground and 2 py excited states of neutral hydrogen atoms. Based on these calculations, we argue that for relatively small impact parameters the electron angular distributions may be strongly affected by altering the position of the atom within the wave front. In contrast, if the atom is placed far from the front centre, the emission pattern of the electrons is independent on the impact parameter b and resembles that observed in the photoionization by plane wave photons.Comment: 23 pages, 6 figure

Bessel beams of two-level atoms driven by a linearly polarized laser field

We study Bessel beams of two-level atoms that are driven by a linearly polarized laser field. Starting from the Schroedinger equation, we determine the states of two-level atoms in a plane-wave field respecting propagation directions both of the atom and the field. For such laser-driven two-level atoms, we construct Bessel beams beyond the typical paraxial approximation. We show that the probability density of these atomic beams obtains a non-trivial, Bessel-squared-type behavior and can be tuned under the special choice of the atom and laser parameters, such as the nuclear charge, atom velocity, laser frequency, and propagation geometry of the atom and laser beams. Moreover, we spatially and temporally characterize the beam of hydrogen and selected (neutral) alkali-metal atoms that carry non-zero orbital angular momentum (OAM). The proposed spatiotemporal Bessel states (i) are able to describe, in principle, twisted states of any two-level system which is driven by the radiation field and (ii) have potential applications in atomic, nuclear processes and quantum communication.Comment: 13 pages, 5 figures, appeared as a EPJD highlight on Thursday, 01 August 2013 http://www.epj.org/index.php?option=com_content&view=article&id=684%3Aepjd-highlight-novel-beams-made-of-twisted-atoms&catid=112%3Aepj-d&Itemid=466&lang=e

Electromagnetic wave propagation in spatially homogeneous yet smoothly time-varying dielectric media

We explore the propagation and transformation of electromagnetic waves through spatially homogeneous yet smoothly time-dependent media within the framework of classical electrodynamics. By modelling the smooth transition, occurring during a finite period {\tau}, as a phenomenologically realistic and sigmoidal change of the dielectric permittivity, an analytically exact solution to Maxwell's equations is derived for the electric displacement in terms of hypergeometric functions. Using this solution, we show the possibility of amplification and attenuation of waves and associate this with the decrease and increase of the time-dependent permittivity. We demonstrate, moreover, that such an energy exchange between waves and non-stationary media leads to the transformation (or conversion) of frequencies. Our results may pave the way towards controllable light-matter interaction in time-varying structures.Comment: 5 figure