Uniform semiclassical approximation in quantum statistical mechanics

We present a simple method to deal with caustics in the semiclassical approximation to the partition function of a one-dimensional quantum system. The procedure, which makes use of complex trajectories, is applied to the quartic double-well potential.Comment: 5 pages, 1 figure, Latex. Contribution to the Proceedings of the XXI Brazilian National Meeting on Particles and Fields (Sao Lourenco, October 23-27, 2000

Modelling of an IR scintillation counter

A systematic study of the excitation and de-excitation mechanisms in ternary gas mixtures Ar+CO2+N2 is presented regarding the possibility of developing a proportional scintillation counter based on the detection of the infrared molecular emissions associated with the lowest vibrational states of molecules. The use of visible or near-infrared photons ([lambda]<1 [mu]m) for applications like imaging and quality control of microstructure detectors has been reported. In view of these applications we analyse the processes leading to near-infrared emissions in pure argon and give an estimation of the number of photons emitted per electron, at several pressures, as a function of the charge gain.http://www.sciencedirect.com/science/article/B6TJM-3YXB101-2M/1/b5bfeb3739389bb6dbe4d84c8746dbf

Nitrogen fluorescence in air for observing extensive air showers

Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of Air Fluorescence Workshops commenced in 2002. At the 8$^{\rm{th}}$ Air Fluorescence Workshop 2011, it was suggested to develop a common way of describing the nitrogen fluorescence for application to air shower observations. Here, first analyses for a common treatment of the major dependences of the emission procedure are presented. Aspects like the contributions at different wavelengths, the dependence on pressure as it is decreasing with increasing altitude in the atmosphere, the temperature dependence, in particular that of the collisional cross sections between molecules involved, and the collisional de-excitation by water vapor are discussed.Comment: 12 pages, 17 figures, 2 tables, International Symposium on Future Directions in UHECR Physics, 13-16 February 2012, CERN, Geneva (Switzerland); the updated version corrects for a typo in Eq. (1

The Plant Propagation Algorithm: Modifications and Implementation

The Plant Propagation Algorithm, epitomised by the Strawberry Algorithm, has been previously successfully tested on low dimensional continuous optimisation problems. It is a neighborhood search algorithm. In this paper, we introduce a robust and efficient version of the algorithm and explain how it can be implemented to compete with one of the best available alternatives, namely the Artificial Bee Colony algorithm and we present an improved and more effective variant on standard continuous optimisation test problem instances in high dimensions. Computational and comparative results are included

Biología reproductiva del Chimango (<i>Polyborus chimango</i>)

En este trabajo se ha estudiado la biología reproductiva del chimango en las provincias de Córdoba y Buenos Aires. En ambos sitios fueron observados grupos de nidos, y una colonia de nidificación (56 nidos en 0,7 ha) fue observada en Córdoba. Como hubo una buena cantidad de árboles apropiados, la disponibilidad de lugar para los nidos no puede explicar la nidificación en grupos; la abundancia de alimento es un factor más probable. El tamaño medio de la postura fue de 2.77 huevos, el período de incubación de 26 a 27 días, y el tiempo de permanencia del pichón en el nido 32 a 34 días. El alimento traído a los pichones incluye insectos ortópteros, anfibios y pequeños mamíferos. Aceptado el 14 de abril de 1986.Reproductive biology of the Chimango Caracara (<i>Polyborus chimango</i>). The reproductive biology of the Chimango Caracara (<i>Polyborus chimango</i> ) was studied in the provinces of Córdoba and Buenos Aires. Champed nesting was observed at both sites, and a dense colony (56 nests in 0.7 ha) was observed in Córdoba. Nest sites at both areas were almost exclusively arboreal. As there were plenty of suitable trees, nest site avaiability cannot explain clumped nesting; abundance of food is a more likely factor. Mean clutch size was 2.77 eggs, the incubation period 26 to 27 days, and the nestling period 32 - 34 days. Food brought to nestlings include orthopteroid insects, amphibians and small mammals

Reuse of nesting scrapes by Kentish Plovers

We studied reuse of nesting scrapes within breeding seasons by Kentish Plovers (Charadrius alexandrinus) in an inland lake of southern Spain over six years. Overall, 5.6% of original nests were reused at least once. We tested whether nest reuse is adaptive, but found no differences in breeding success between those pairs that reused nests and those that did not. We also tested whether nest reuse should be more frequent when scrapes are difficult to excavate than when it is easier to excavate them, and found that nests on hard substrates were more frequently reused than nests on soft substrates, and that nest reuse was more frequent in the second half of the season, when the nesting substrate is harder, than in the first half of the season. This suggests that nest reuse may save Kentish Plovers some energy.Peer Reviewe

Pressure of massless hot scalar theory in the boundary effective theory framework

We use the boundary effective theory (BET) approach to thermal field theory in order to calculate the pressure of a system of massless scalar fields with quartic interaction. The method naturally separates the infrared physics, and is essentially non-perturbative. To lowest order, the main ingredient is the solution of the free Euler-Lagrange equation with non-trivial (time) boundary conditions. We derive a resummed pressure, which is in good agreement with recent calculations found in the literature, following a very direct and compact procedure.Comment: 10 pages, 4 figure