An Examination of the Impacts of Exchange Rate Volatility on Sectoral Trade in the Mercosur

This study captures the lack of macroeconomic policy coordination among Mercosur countries, through the impact of real bilateral exchange rate volatility on trade. A sectoral gravity model is estimated under two different measures of exchange rate volatility. Results show that the reduction in exchange rate volatility can increase bilateral trade.International Relations/Trade,

State-Relevant Maxwell's Equation from Kaluza-Klein Theory

We study a five-dimensional perfect fluid coupled with Kaluza-Klein (KK) gravity. By dimensional reduction, a modified form of Maxwell's equation is obtained, which is relevant to the equation of state of the source. Since the relativistic magnetohydrodynamics (MHD) and the 3-dimensional formulation are widely used to study space matter, we derive the modified Maxwell's equations and relativistic MHD in 3+1 form. We then take an ideal Fermi gas as an example to study the modified effect, which can be visible under high density or high energy condition, while the traditional Maxwell's equation can be regarded as a result in the low density and low temperature limit. We also indicate the possibility to test the state-relevant effect of KK theory in a telluric laboratory.Comment: 11 pages, 3 figures; version published in PR

Lattice Boltzmann method for weakly ionized isothermal plasmas

In this paper, a lattice Boltzmann method (LBM) for weakly ionized isothermal plasmas is presented by introducing a rescaling scheme for the Boltzmann transport equation. Without using this rescaling, we found that the nondimensional relaxation time used in the LBM is too large and the LBM does not produce physically realistic results. The developed model was applied to the electrostatic wave problem and the diffusion process of singly ionized helium plasmas with a 1-3% degree of ionization under an electric field. The obtained results agree well with theoretical values.open8

Metazoários e protozoários parasitando tilápias do Nilo Oreochromis niloticus (Cichlidae) cultivadas em Macapá (AP), Amazônia Oriental.

Resumo simples

Gaussian coordinate systems for the Kerr metric

We present the whole class of Gaussian coordinate systems for the Kerr metric. This is achieved through the uses of the relationship between Gaussian observers and the relativistic Hamilton-Jacobi equation. We analyze the completeness of this coordinate system. In the appendix we present the equivalent JEK formulation of General Relativity -- the so-called quasi-Maxwellian equations -- which acquires a simpler form in the Gaussian coordinate system. We show how this set of equations can be used to obtain the internal metric of the Schwazschild solution, as a simple example. We suggest that this path can be followed to the search of the internal Kerr metric

Impactos da volatilidade da taxa de câmbio no comércio setorial do Mercosul

This study captures the impact of real bilateral exchange rate volatility on trade. A sectoral gravity model is estimated under two different measures of exchange rate volatility. Results show that a reduction in exchange rate volatility, an increase in the countrys income, and a reduction in trade tariffs can increase bilateral trade in Mercosur. This study suggests the inclusion and implementation of common, stable, and integrated policies among Mercosur countries, aiming to reduce the adverse effects of the exchange rate volatility on bilateral trade among these countries.Este estudo capta o impacto da volatilidade da taxa de câmbio real bilateral no comércio. Estima-se um modelo gravitacional setorial utilizando-se duas medidas de volatilidade da taxa de câmbio. Os resultados mostram que uma redução na volatilidade da taxa de câmbio, o crescimento da renda e a redução das tarifas comerciais contribuem para aumentar o comércio bilateral no Mercosul. Este estudo sugere a inclusão e implementação de políticas comuns, estáveis e integradas entre os países do Mercosul, de modo a reduzir os impactos adversos da volatilidade cambial no comércio dos países envolvidos

Atomic Configuration of Nitrogen Doped Single-Walled Carbon Nanotubes

Having access to the chemical environment at the atomic level of a dopant in a nanostructure is crucial for the understanding of its properties. We have performed atomically-resolved electron energy-loss spectroscopy to detect individual nitrogen dopants in single-walled carbon nanotubes and compared with first principles calculations. We demonstrate that nitrogen doping occurs as single atoms in different bonding configurations: graphitic-like and pyrrolic-like substitutional nitrogen neighbouring local lattice distortion such as Stone-Thrower-Wales defects. The stability under the electron beam of these nanotubes has been studied in two extreme cases of nitrogen incorporation content and configuration. These findings provide key information for the applications of these nanostructures.Comment: 25 pages, 13 figure

Hemispheric asymmetries in the ionospheric response observed in the American sector during an intense geomagnetic storm

The main purpose of this investigation is to study the ionospheric F region response induced by the intense geomagnetic storm that occurred on 7-8 September 2002. The geomagnetic index Dst reached a minimum of -181 nT at 0100 UT on 8 September. In this study, we used observations from a chain of 12 GPS stations and another chain of 6 digital ionosonde stations. It should be mentioned that, soon after the sudden commencement (SC) at 1637 UT on 7 September, the TEC variations at midlatitude stations in both hemispheres showed an F region positive storm phase. However, during the recovery phase, a strong hemispheric asymmetry was observed in the ionospheric response. While a TID type soliton was observed to propagate in the Southern American sector, no TID activity was seen in the Northern American sector. Also, in the Southern Hemisphere, the TEC variations were less affected by the geomagnetic storm. The Northern Hemisphere observations showed a strong and long-lasting negative F region storm phase starting at about 1000 UT on 8 September (lasting for about 24 h). A perusal of TEC phase fluctuations and equatorial spread-F (ESF) ionospheric sounding data indicates that, on the disturbed night of 7-8 September, some stations showed the occurrence of ESF starting at about 0000 UT (2000 LT) on 8 September, whereas other stations showed that the ESF occurrence started much later, at about 0800 UT (0500 LT). This hemispheric asymmetric response of the ionospheric F region possibly indicates the presence of different mechanisms for the generation of ESF along the various latitudinal regions during the disturbed period.Facultad de Ciencias Astronómicas y Geofísica

Hemispheric asymmetries in the ionospheric response observed in the American sector during an intense geomagnetic storm

The main purpose of this investigation is to study the ionospheric F region response induced by the intense geomagnetic storm that occurred on 7-8 September 2002. The geomagnetic index Dst reached a minimum of -181 nT at 0100 UT on 8 September. In this study, we used observations from a chain of 12 GPS stations and another chain of 6 digital ionosonde stations. It should be mentioned that, soon after the sudden commencement (SC) at 1637 UT on 7 September, the TEC variations at midlatitude stations in both hemispheres showed an F region positive storm phase. However, during the recovery phase, a strong hemispheric asymmetry was observed in the ionospheric response. While a TID type soliton was observed to propagate in the Southern American sector, no TID activity was seen in the Northern American sector. Also, in the Southern Hemisphere, the TEC variations were less affected by the geomagnetic storm. The Northern Hemisphere observations showed a strong and long-lasting negative F region storm phase starting at about 1000 UT on 8 September (lasting for about 24 h). A perusal of TEC phase fluctuations and equatorial spread-F (ESF) ionospheric sounding data indicates that, on the disturbed night of 7-8 September, some stations showed the occurrence of ESF starting at about 0000 UT (2000 LT) on 8 September, whereas other stations showed that the ESF occurrence started much later, at about 0800 UT (0500 LT). This hemispheric asymmetric response of the ionospheric F region possibly indicates the presence of different mechanisms for the generation of ESF along the various latitudinal regions during the disturbed period.Facultad de Ciencias Astronómicas y Geofísica

Considerations about Ucides cordatus cordatus fishing in the Parnaíba River Delta Region, Brazil.

The uçá-crab, Ucides cordatus cordatus, is distinguished as one of the most explored fisherie resources in Brazil. The Parnaíba River Delta Region, located between the states of Piauí and Maranhão, has the greatest concentration of crab catcher in the entire country. Evidence of over-exploitation highlights need of better control over crab fishing activities in this region. The present work has as objective to determine the uçá-crab capture per effort unit (CPUE) in the Parnaíba River Delta, in order to supply subsidies for the fisherie management of this resorce. Fishery data collection was carried out during 1999 throughout 2002, between the latitudes 2º40' and 2º45' and the longitudes 41º51' and 42º05'. The CPUE was determined as the number of crabs captured by catcher per day. The total monthly capture was esteemed considering the average between all years and the number of 4.500 operating catchers in the region. The average CPUE values varied between 14.6 and 22.6 crabs per catcher per day. The total monthly capture varied between 1.314.000 and 2.034.000 crabs, in the months of minimum and maximum CPUE, respectively. In the period of one year, about 21 millium crabs are captured. The obtained results, added to the over-fishing indications, bring to the conclusion that the collapse of crab fishing is a question of time in the region of the Parnaíba River Delta if the appropriate measures for adequate managing of the resource.Proceedings of the 8thInternational Coastal Symposium - ICS 2004