Vortex equations in abelian gauged sigma-models

We consider nonlinear gauged sigma-models with Kahler domain and target. For a special choice of potential these models admit Bogomolny (or self-duality) equations -- the so-called vortex equations. We find the moduli space and energy spectrum of the solutions of these equations when the gauge group is a torus T^n, the domain is compact, and the target is C^n or CP^n. We also obtain a large family of solutions when the target is a compact Kahler toric manifold.Comment: v2: 60 pages, more details than in CMP versio

Moduli Spaces of Abelian Vortices on Kahler Manifolds

We consider the self-dual vortex equations on a positive line bundle L --> M over a compact Kaehler manifold of arbitrary dimension. When M is simply connected, the moduli space of vortex solutions is a projective space. When M is an abelian variety, the moduli space is the projectivization of the Fourier-Mukai transform of L. We extend this description of the moduli space to the abelian GLSM, i.e. to vortex equations with a torus gauge group acting linearly on a complex vector space. After establishing the Hitchin-Kobayashi correspondence appropriate for the general abelian GLSM, we give explicit descriptions of the vortex moduli space in the case where the manifold M is simply connected or is an abelian variety. In these examples we compute the Kaehler class of the natural L^2-metric on the moduli space. In the simplest cases we compute the volume and total scalar curvature of the muduli space. Finally, we note that for abelian GLSM the vortex moduli space is a compactification of the space of holomorphic maps from M to toric targets, just as in the usual case of M being a Riemann surface. This leads to various natural conjectures, for instance explicit formulae for the volume of the space of maps CP^m --> CP^n.Comment: v2: 48 pages; significant changes; description of the vortex moduli spaces of the GLSM extended to allow general values of the parameters, beyond the generic values of v

A study of the evolution of the accretion disk of V2051 Oph through two outburst cycles

We follow the changes in the structure of the accretion disk of the dwarf nova V2051 Oph along two separate outbursts in order to investigate the causes of its recurrent outbursts. We apply eclipse mapping techniques to a set of light curves covering a normal (July 2000) and a low-amplitude (August 2002) outburst to derive maps of the disk surface brightness distribution at different phases along the outburst cycles. The sequence of eclipse maps of the 2000 July outburst reveal that the disk shrinks at outburst onset while an uneclipsed component of 13 per cent of the total light develops. The derived radial intensity distributions suggest the presence of an outward-moving heating wave during rise and of an inward-moving cooling wave during decline. The inferred speed of the outward-moving heating wave is ~ 1.6 km/s, while the speed of the cooling wave is a fraction of that. A comparison of the measured cooling wave velocity on consecutive nights indicates that the cooling wave accelerates as it travels towards disk center, in contradiction with the prediction of the disk instability model. From the inferred speed of the heating wave we derive a viscosity parameter alpha_{hot} ~ 0.13, comparable to the measured viscosity parameter in quiescence. The 2002 August outburst had lower amplitude (\Delta B ~ 0.8 mag) and the disk at outburst maximum was smaller than on 2000 July. For an assumed distance of 92 pc, we find that along both outbursts the disk brightness temperatures remain below the minimum expected according to the disk instability model. The results suggest that the outbursts of V2051 Oph are caused by bursts of increased mass transfer from the mass-donor star.Comment: 22 pages, 11 postscript figures, written with aastex macro package. To appear in the August 2007 issue of The Astronomical Journa

Tilted excitation implies odd periodic resonances

This work was supported by the Brazilian agencies FAPESP and CNPq. MSB also acknowledges the Engineering and Physical Sciences Research Council grant Ref. EP/I032606/1. GID thanks Felipe A. C. Pereira for fruitful discussions.Peer reviewedPostprin

Correction to: Northerly wind trends along the Portuguese marine coast since 1950

All figure captions are not accurate. Also, there is a repeated error in most figures because the vertical scales incorrectly show Wind Strenght instead of Wind Strength and in Fig. 4 (mid-panel) 2003 instead of 2004.info:eu-repo/semantics/publishedVersio

Globalization trends and regional development - dynamics of FDI and human capital flows

This is a post-peer-review, pre-copyedit version of an article published in [European Journal of Development Research]. The definitive publisher-authenticated version [European Journal of Development Research 26, 160-161 (January 2014)] is available online at: http://www.palgravejournals.com/ejdr/journal/v26/n1/full/ejdr201354a.htmlApparently rendered irrelevant by globalization, regions have been rediscovered as a force in economic and social development by both scholars and policymakers. Localized inter-personal ties and networks are seen as important resources (Woolcock and Narayan, 2000), and the local supply of entrepreneurs has emerged as a key determinant of future economic growth (Chatterji et al, 2013)

V2051 Ophiuchi after superoutburst : out-of-plane material and the superhump light source

Aims. We performed a detailed spectroscopic analysis of the dwarf nova V2051 Oph at the end of its 1999 superoutburst. We studied and interpreted the simultaneous behaviour of various emission lines. Methods. We obtained high-resolution echelle spectroscopic data at ESO’s NTT with EMMI, covering the spectral range of 4000–7500 Å. The analysis was performed using standard IRAF tools. The indirect imaging technique of Doppler tomography was applied, in order to map the accretion disc and distinguish between the different emission sources. Results. The spectra are characterised by strong Balmer emission, together with lines of He i and the iron triplet Fe ii 42. All lines are double-peaked, but the blue-to-red peak strength and central absorption depth vary. The primary’s velocity was found to be 84.9 kms−1. The spectrograms of the emission lines reveal the prograde rotation of a disc-like emitting region and, for the Balmer and He i lines, an enhancement of the red-wing during eclipse indicates a bright spot origin. The modulation of the double-peak separation shows a highly asymmetric disc with non-uniform emissivity. This is confirmed by the Doppler maps, which apart from the disc and bright spot emission also indicate an additional region of enhanced emission in the 4th quadrant (+Vx, −Vy), which we associate with the superhump light source. Given the behaviour of the iron triplet and its distinct differences from the rest of the lines, we attribute its existence to an extended gas region above the disc. Its origin can be explained through the fluorescence mechanism

Concepções de ensino de professores de física e química

Em Portugal , o currículo nacional das ciências para o ensino básico apresenta um foco construtivista, valorizando abordagens de ensino centradas nos alunos como resolução de problemas e investigações e enfatiza a interligação entre Ciência, Tecnologia, Sociedade e Ambiente. Apela para o uso de experiências de aprendizagem que incluem, formulação de questões, planeamento e realização de investigações, recolha de dados e argumentação com base em evidências. Contudo, as concepções de ensino dos professores influenciam o modo como as experiências educativas são implementadas. Neste estudo, descrevem-se concepções de ensino de seis professores de física e química. Assenta numa metodologia interpretativa usando, na análise de dados, o questionamento e comparação constantes. Os dados sugerem que os professores ainda não aderiram às ideias inovadoras propostas