Five-Dimensional QED, Muon Pair Production and Correction to the Coulomb Potential

We consider QED in five dimensions in a configuration where matter is localized on a 3-brane while foton propagates in the bulk. The idea is to investigate the effects of the Kaluza-Klein modes of the photon in the relativistic regime, but in low energy, and in the nonrelativistic regime. In the relativistic regime, we calculate the cross section for the reaction $e^+ + e^- \to \mu^+ + \mu^-$. We compare our theoretical result with a precise measurement of this cross section at $\sqrt{s}=57.77$ GeV. As result, we extract a lower bound on the size of the extra dimension. In the nonrelativistic regime, we derive the contribution for the Coulomb potential due to the whole tower of the Kaluza-Klein excited modes of the photon. We use the modified potential to calculate the Rutherford scattering differential cross section.Comment: minor changes, three new refs. added, to appear in IJMP

Estimating submarine groundwater discharge into the Ria Formosa lagoon, Portugal: Uncertainties in the lagoon-open ocean radium exchange

The Ria Formosa lagoon is the most important resource for the fishing, aquaculture and tourism industries of southern Portugal. The lagoon expands across an area of approximately 100 km²and about half of its area is intertidal, covered with muddy sand and saltmarshes. The lagoon is shallow (2 m average depth) with semidiurnal tides at amplitudes between 1.3 m and 3 m (during neap and spring tides respectively) causing a relatively rapid renewal of water through three inlets at time scales shorter than 5 days. The hinterland is characterized by intensive agriculture leading to elevated nitrate concentrations in coastal groundwaters. To quantify the amount of submarine groundwater discharge (SGD) and possible associated nutrient fluxes to the lagoon radium concentrations (223Ra, 224Ra, 228Ra, 226Ra) were measured during low and high spring tides in December 2009 and May 2010 using standard techniques (delayed coincidence counting, gamma spectrometry). A radium mass balance model accounting for all major sources and sinks of radium was employed to derive quantitative estimates of SGD. In order to avoid biases due to non-representative sampling, areal average radium concentrations were generated using the ArcGIS spatial analyst interpolation scheme. Radium exchange with the open ocean was the most significant parameter in the mass balance calculations. Three independent models were used to calculate this exchange flux: i) a tidal prism model using radium to calculate the return flow factor, ii) a hydrographic model providing outflow and inflow water fluxes for the Ria Formosa lagoon; and by combining these fluxes with the average concentrations measured at the inlet; iii) a model which estimates the exchange with the ocean based on the radium residence time calculated from the water exposure time in the lagoon. For each of these models we calculated SGD based on 223Ra, 224Ra and 226Ra mass balances the differences being at a maximum no greater than 35 %. However, the results from the models differed up to a factor of 2 with the tidal prism model producing the highest estimate and the residence time model the lowest estimates. We will discuss possible causes for the differences in the model results

A Kalman filter application to a spectral wave model

International audienceA sequential time dependent data assimilation scheme based on the Kalman filter is applied to a spectral wave model. Usually, the first guess covariance matrices used in optimal interpolation schemes are exponential spreading functions, which remain constant. In the present work the first guess correlation errors evolve in time according to the dynamic constraints of the wave model. A system error noise is deduced and used to balance numerical errors. The assimilation procedure is tested in a standard situation of swell propagation, where the Kalman filter is used to assimilate the significant wave height. The evolution of the wave field is described by a linear two-dimensional advection equation and the propagation of the error covariance matrix is derived according to Kalman's linear theory. Model simulations were performed in a 2-dimensional domain with deep-water conditions, a relatively small surface area and without wind forcing or dissipation. A true state simulation and a first guess simulation were used to illustrate the assimilation outcome, showing a reasonable performance of the Kalman filter

The Suitability for Organic Cattle Beef Production of Mixed Farming Systems in the Highlands of North East Portugal

The EC Reg. 1804/99 takes account of animal production in organic farming. However, these specifications may limit implementation and expansion of organic animal production, due to environmental and system constraints. Mixed farming, as defined by Spedding (1988) and Grigg (1996), is commonly practiced in the NE highlands of Portugal. Two farms were studied in this region in order to evaluate their suitability for organic cattle beef production, taking account of the technical specifications of the EC regulation

Influence of up-flow velocity on the performance of an anaerobic filter under oleic acid overloads

An upflow velocity of 0.21 m h−1 was optimal to minimize the effect of organic shocks (from 6 to 30 kg COD m−3 d−1) when operating an upflow anaerobic filter for the treatment of an oleic acid-based effluent (50% w/v COD). This value represented the transition between a mass transfer controlled regime and a kinetic regime. Under hydraulic shock loads, an increase in upflow velocity from 0.3 to 0.4 m h−1 decreased the removal efficiency from 68 to 51%

Comment on ``Majoron emitting neutrinoless double beta decay in the electroweak chiral gauge extensions''

We point out that if the majoron-like scheme is implemented within a 331 model, there must exist at least three different mass scales for the scalar vacuum expectation values in the model.Comment: 4 pages, no figures, Revtex. To be published in Physical Review