Patrimoni cultural subaquàtic: estat de la qüestió

Màster Oficial en Gestió del Patrimoni Cultural

La Biblioteca de Catalunya: una difusió del patrimoni amb visió de futur

Màster Oficial en Estudis Avançats en Història de l'Art. Curs: 2008-2009. Directora: Imma Socias

Què ens oculta el vel estadístic? Reflexió feminista entorn del disseny i l'explotació de les fonts de dades socials (part 1 de 5)

Ponent: Marta Luxan / Presenta: Ruth Vilà

Què ens oculta el vel estadístic? Reflexió feminista entorn del disseny i l'explotació de les fonts de dades socials (part 2 de 5)

Ponent: Marta Luxan / Presenta: Ruth Vilà

Què ens oculta el vel estadístic? Reflexió feminista entorn del disseny i l'explotació de les fonts de dades socials (part 3 de 5)

Ponent: Marta Luxan / Presenta: Ruth Vilà

Què ens oculta el vel estadístic? Reflexió feminista entorn del disseny i l'explotació de les fonts de dades socials (part 4 de 5)

Ponent: Marta Luxan / Presenta: Ruth Vilà

Què ens oculta el vel estadístic? Reflexió feminista entorn del disseny i l'explotació de les fonts de dades socials (part 5 de 5)

Ponent: Marta Luxan / Presenta: Ruth Vilà

Premartensitic and martensitic phase transitions in ferromagnetic Ni2MnGa

We present an experimental study of the premartensitic and martensitic phase transitions in a Ni2MnGa single crystal by using ultrasonic techniques. The effect of applied magnetic field and uniaxial compressive stress has been investigated. It has been found that they substantially modify the elastic and magnetic behavior of the alloy. These experimental findings are a consequence of magnetoelastic effects. The measured magnetic and vibrational behavior agrees with the predictions of a recently proposed Landau-type model [A. Planes et al., Phys. Rev. Lett. 79, 3926 (1997)] that incorporates a magnetoelastic coupling as a key ingredient.

Freezing of 4He and its liquid-solid interface from density functional theory

We show that, at high densities, fully variational solutions of solidlike types can be obtained from a density functional formalism originally designed for liquid 4He . Motivated by this finding, we propose an extension of the method that accurately describes the solid phase and the freezing transition of liquid 4He at zero temperature. The density profile of the interface between liquid and the (0001) surface of the 4He crystal is also investigated, and its surface energy evaluated. The interfacial tension is found to be in semiquantitative agreement with experiments and with other microscopic calculations. This opens the possibility to use unbiased density functional (DF) methods to study highly nonhomogeneous systems, like 4He interacting with strongly attractive impurities and/or substrates, or the nucleation of the solid phase in the metastable liquid.

Condensation of helium in nanoscopic alkali wedges at zero temperature

We present a complete calculation of the structure of liquid 4He confined to a concave nanoscopic wedge, as a function of the opening angle of the walls. This is achieved within a finite-range density functional formalism. The results here presented, restricted to alkali metal substrates, illustrate the change in meniscus shape from rather broad to narrow wedges on weak and strong alkali adsorbers, and we relate this change to the wetting behavior of helium on the corresponding planar substrate. As the wedge angle is varied, we find a sequence of stable states that, in the case of cesium, undergo one filling and one emptying transition at large and small openings, respectively. A computationally unambiguous criterion to determine the contact angle of 4He on cesium is also proposed.

The role of energy correlations on Coulomb suppression in ballistic conductors contacted to degenerate reservoirs

Coulomb suppression of shot noise in a ballistic diode connected to degenerate ideal contacts is analyzed in terms of the correlations taking place between current fluctuations due to carriers injected with different energies. By using Monte Carlo simulations we show that at low frequencies the origin of Coulomb suppression can be traced back to the negative correlations existing between electrons injected with an energy close to that of the potential barrier present in the diode active region and all other carriers injected with higher energies. Correlations between electrons with energy above the potential barrier with the rest of electrons are found to influence significantly the spectra at high frequency in the cutoff region.