Soil acidification with a specific view to aluminium

Algaba Carrasco, P. (2011). Soil acidification with a specific view to aluminium. Universitat Politècnica de València. http://hdl.handle.net/10251/9968Archivo delegad

Probing Helical Magnetic Fields in AGN by Rotation Measure Gradients Studies

One of the tools that can provide evidence about the existence of helical magnetic fields in AGN is the observation of rotation measure gradients across the jet. Such observations have been previously made successfully, proving that such gradients are far from being rare, but common and typically persistent over several years, although some of them may show a reversal in the direction along the jet. Further studies of rotation measure gradients can help us in our understanding of the magnetic field properties and structure in the base of the jets. We studied Very Long Baseline Array (VLBA) polarimetric observations of 8 sources consistent of some quasars and BL Lacs at 12, 15, 22, 24 and 43 GHz and we find that all but two sources show indications of rotation measure gradients, either parallel or perpendicular to the jet. We interpret gradients perpendicular to the jet as indications of the change of the line of sight of the magnetic field due to its helicity, and gradients parallel to the jet as the decrease of magnetic field strength and/or electron density as we move along the jet. When comparing our results with the literature, we find tentative evidence of a rotation measure gradient flip, which can be explained as a change of the pitch angle or jet bending.Comment: 4 pages, 2 figures. Contribution for the Proceedings of HEPRO3 (Barcelona, 27 June - 1 July 2011). To be published on the International Journal of Modern Physics Conference Series, edited by J.M. Paredes, M. Rib\'o, F.A. Aharonian and G.E. Romer

Early kinetics of intestinal infection and immune responses to two Toxoplasma gondii strains in pigs

Toxoplasma gondiiis an obligate intracellular parasite, able to infect all homeothermicanimals mostly through ingestion of (oo)cysts contaminated food or water. Recently,we observed aT. gondiistrain-specific clearance from tissues upon infection in pigs:while the swine-adapted LR strain persisted in porcine tissues, a subsequent infectionwith the human-isolated Gangji strain cleared parasites from several tissues. Wehypothesized that intestinal immune responses shortly after infection might play a rolein this strain-specific clearance. To assess this possibility, the parasite load in smallintestinal lymph node cells and blood immune cells as well asthe IFNγsecretion bythese cells were evaluated at 2, 4, 8, 14, and 28 days post oralinoculation of pigs withtissue cysts of both strains. Interestingly, at day 4 post inoculation with the LR strainthe parasite was detected by qPCR only in the duodenal lymph node cells, while in thejejunal and ileal lymph node cells and PBMCs the parasite wasdetected from day 8post inoculation onwards. Although we observed a similar profile upon inoculation withthe Gangji strain, the parasite load in the examined cells was much lower. This wasreflected in a significantly higherT. gondii-specific serum IgG response in LR comparedto Gangji infected pigs at day 28 post inoculation. Unexpectedly, this was not reflected inthe IFNγsecretion upon re-stimulation of the cells where almost equal IFNγsecretion wasobserved in both groups. In conclusion, our results show thatT. gondiifirst enters thehost at the duodenum and then probably disseminates from this site to the other tissues.How the early immune response influences the clearance of parasite from tissues needsfurther study