On the Integrability and Chaos of an N=2 Maxwell-Chern-Simons-Higgs Mechanical Model

We apply different integrability analysis procedures to a reduced (spatially homogeneous) mechanical system derived from an off-shell non-minimally coupled N=2 Maxwell-Chern-Simons-Higgs model that presents BPS topological vortex excitations, numerically obtained with an ansatz adopted in a special - critical coupling - parametric regime. As a counterpart of the regularity associated to the static soliton-like solution, we investigate the possibility of chaotic dynamics in the evolution of the spatially homogeneous reduced system, descendant from the full N=2 model under consideration. The originally rich content of symmetries and interactions, N=2 susy and non-minimal coupling, singles out the proposed model as an interesting framework for the investigation of the role played by (super-)symmetries and parametric domains in the triggering/control of chaotic behavior in gauge systems. After writing down effective Lagrangian and Hamiltonian functions, and establishing the corresponding canonical Hamilton equations, we apply global integrability Noether point symmetries and Painleveproperty criteria to both the general and the critical coupling regimes. As a non-integrable character is detected by the pair of analytical criteria applied, we perform suitable numerical simulations, as we seek for chaotic patterns in the system evolution. Finally, we present some Comments on the results and perspectives for further investigations and forthcoming communications.Comment: 18 pages, 5 figure

Attachment of Staphylococcus epidermidis RP62A to chemically modified cellulose derivatives

Coagulase negative staphylococci, most notably Staphylococcus epidermidis, have been identified as a predominant cause of cardiovascular implant infection, which begins with the colonization of the device by the bacteria. One possible approach to reduce this event is to understand how the physicochemical properties of bacterial surface influence attachment to biomaterials. In the present study, the attachment of coagulase negative Staphylococcus epidermidis expressing capsular polysaccharide/adhesin (PS/A), the most common etiological agent of colonization of implantable medical devices, was assessed in vitro to cellulose diacetate (CDA), to CDA chemically modified by de-acetylation (CDA-D) and by phosphorylation (CDA-P), as well as to reference Low Density Polyethylene (LDPE). The quantification of S. epidermidis attached to cellulose diacetate (CDA) in phosphate buffer saline (PBS) elicited information regarding the interaction between the bacterial strain and the polymeric biomaterial. There was a significant difference in the adhesion of RP62A to CDA, compared to LDPE. Chemical modifications of CDA by de-acetylation and by phosphorylation were effective in lowering bacterial attachment. These chemical treatments increased the acidic parameter of the surface energy and decreased the acid-base interactions with acidic sites of the capsular PS/A. In other terms, these treatments also promoted a decrease in hydrophobicity that linearly correlates with a decrease in the number of attached cells

Monitoring natural organic matter in surface water by UV spectroscopy : effects of calcium, magnesium and pH value

The aim of this study was to evaluate the effects of dissolved magnesium and calcium ions on the determination of humic substances in water by spectrophotometry at 254 nm. Quantifications were carried out for different pH values, both with and without filtration of the samples. The smallest effects were observed for unfiltered samples and neutral pH values.Fundação para a Ciência e a Tecnologia (FCT) - Project POCI-2010, measure IV.3 and reference n.º SFRH / BD / 18565 / 2004

The new automated daily mortality surveillance system

The experience reported in an earlier Eurosurveillance issue on a fast method to evaluate the impact of the 2003 heatwave on mortality in Portugal, generated a daily mortality surveillance system (VDM) that has been operating ever since jointly with the Portuguese Heat Health Watch Warning System. This work describes the VDM system and how it evolved to become an automated system operating year-round, and shows briefly its potential using mortality data from January 2006 to June 2009 collected by the system itself. The new system has important advantages such as: rapid information acquisition, completeness (the entire population is included), lightness (very little information is exchanged, date of death, age, sex, place of death registration). It allows rapid detection of impacts (within five days) and allows a quick preliminary quantification of impacts that usually took several years to be done. These characteristics make this system a powerful tool for public health action. The VDM system also represents an example of inter-institutional cooperation, bringing together organisations from two different ministries, Health and Justice, aiming at improving knowledge about the mortality in the population

Multimode Hong-Ou-Mandel Interferometry

We review some recent experiments based upon multimode two-photon interference of photon pairs created by spontaneous parametric down-conversion. The new element provided by these experiments is the inclusion of the transverse spatial profiles of the pump, signal and idler fields. We discuss multimode Hong-Ou-Mandel interference, and show that the transverse profile of the pump beam can be manipulated in order to control two-photon interference. We present the basic theory and experimental results as well as several applications to the field of quantum information.Comment: 20 pages, 14 figures, Brief Review to be published in Modern Physics Letters

Gauge dependenceof the order parameter anomalous dimension in the Ginzburg-Landau model and the critical fluctuations in superconductors

The critical fluctuations of superconductors are discussed in a fixed dimension scaling suited to describe the type II regime. The gauge dependence of the anomalous dimension of the scalar field is stablished exactly from the Ward-Takahashi identities. Its fixed point value gives the $\eta$ critical exponent and it is shown that $\eta$ is gauge independent, as expected on physical grounds. In the scaling considered, $\eta$ is found to be zero at 1-loop order, while $\nu\approx 0.63$. This result is just the 1-loop values for the XY model obtained in the fixed dimension renormalization group approach. It is shown that this XY behavior holds at all orders. The result $\eta=\eta_{XY}$ should be contrasted with the negative values frequently reported in the literature.Comment: EuroLaTex, 7 pages, 2 figures, reference updated; version to be published in Europhysics Letter