A Remark on Lorentz Violation at Finite Temperature

We investigate the radiatively induced Chern-Simons-like term in four-dimensional field theory at finite temperature. The Chern-Simons-like term is temperature dependent and breaks the Lorentz and CPT symmetries. We find that this term remains undetermined although it can be found unambiguously in different regularization schemes at finite temperature.Comment: To appear in JHEP, 8 pages, 1 eps figure, minor changes and references adde

Lorentz-CPT violation, radiative corrections and finite temperature

In this work we investigate the radiatively induced Chern-Simons-like terms in four-dimensions at zero and finite temperature. We use the approach of rationalizing the fermion propagator up to the leading order in the CPT-violating coupling $b_\mu$. In this approach, we have shown that although the coefficient of Chern-Simons term can be found unambiguously in different regularization schemes at zero or finite temperature, it remains undetermined. We observe a correspondence among results obtained at finite and zero temperature.Comment: To appear in JHEP, 10 pages, 1 eps figure, minor changes and references adde

Leguminous cover crops improve the profitability and the sustainability of rainfed olive (Olea europaea L.) orchards: from soil biology to physiology of yield determination

The olive sector has a crucial economic, social, cultural and ecological relevance in the Mediterranean region, where tillage and herbicides application still are generalized practices. However, these techniques oppose to the recommendations of UE policy. Thus, other methods are needed to reduce adverse environmental impacts and to improve biodiversity, soil carbon sink and fertility, to save fossil fuels and to increase yield and the safety and nutritional value of food products. Meanwhile, since Mediterranean basin is particularly vulnerable to climate change, including lower precipitation in summer, olive tree will experiment some hard changes, mainly under rainfed conditions. Therefore, we propose an adequate management of cover crops to shift tillage and herbicides, in order to minimize runoff and evaporation water losses, conserve soil moisture storage and promote the infiltration of water in soil. The experiment was carried out during 4 years on a commercial orchard (cv. Cobrançosa) in Northeast Portugal. The treatments laid out were: (1) ordinary tillage techniques (OT) used by local growers (two tillage trips per year); (2) cover crop with self-reseeding annual legume species (AL); (3) natural vegetation fertilized (NVF) with 60 kg N hm2 (as in OT); (4) natural vegetation (NV) left unfertilized. The results revealed that AL treatment is the best option, reaching 37, 53 and 95% higher cumulative yield than NVF, OT and NV, respectively, in a closely association with greater physiological performance during the summer, mainly evidenced by lower oxidative damage and by favourable changes in water status and net photosynthetic rate, due to lower stomatal and mesophyll limitations. Moreover, the AL covered soil presented considerable microbial diversity and enzymatic activities, which may contribute to promote and conserve soil quality and health, as well the stability of ecosystems. Thus, leguminous cover crops improve the profitability and the sustainability of rainfed olive orchards.info:eu-repo/semantics/publishedVersio

Stationary solutions for the parity-even sector of the CPT-even and Lorentz-covariance-violating term of the standard model extension

In this work, we focus on some properties of the parity-even sector of the CPT-even electrodynamics of the standard model extension. We analyze how the six non-birefringent terms belonging to this sector modify the static and stationary classical solutions of the usual Maxwell theory. We observe that the parity-even terms do not couple the electric and magnetic sectors (at least in the stationary regime). The Green's method is used to obtain solutions for the field strengths E and B at first order in the Lorentz- covariance-violating parameters. Explicit solutions are attained for point-like and spatially extended sources, for which a dipolar expansion is achieved. Finally, it is presented an Earth-based experiment that can lead (in principle) to an upper bound on the anisotropic coefficients as stringent as $(\widetilde{\kappa}_{e-}) ^{ij}<2.9\times10^{-20}.$Comment: 8 pages, revtex style, revised published version, to appear in EPJC (2009

Competition between decay and dissociation of core-excited OCS studied by X-ray scattering

We show the first evidence of dissociation during resonant inelastic soft X-ray scattering. Carbon and oxygen K-shell and sulfur L-shell resonant and non-resonant X-ray emission spectra were measured using monochromatic synchrotron radiation for excitation and ionization. After sulfur, L2,3 -> {\pi}*, {\sigma}* excitation, atomic lines are observed in the emission spectra as a consequence of competition between de-excitation and dissociation. In contrast the carbon and oxygen spectra show weaker line shape variations and no atomic lines. The spectra are compared to results from ab initio calculations and the discussion of the dissociation paths is based on calculated potential energy surfaces and atomic transition energies.Comment: 12 pages, 6 pictures, 2 tables, http://link.aps.org/doi/10.1103/PhysRevA.59.428

Noncommutative massive Thirring model in three-dimensional spacetime

We evaluate the noncommutative Chern-Simons action induced by fermions interacting with an Abelian gauge field in a noncommutative massive Thirring model in (2+1)-dimensional spacetime. This calculation is performed in the Dirac and Majorana representations. We observe that in Majorana representation when $\theta$ goes to zero we do not have induced Chern-Simons term in the dimensional regularization scheme.Comment: Accepted to Phys. Rev. D; 9 pages, Revtex4, no figures, references added, minor improvements, Eq.31 correcte

FGFR1 and PROKR2 rare variants found in patients with combined pituitary hormone deficiencies.

The genetic aetiology of congenital hypopituitarism (CH) is not entirely elucidated. FGFR1 and PROKR2 loss-of-function mutations are classically involved in hypogonadotrophic hypogonadism (HH), however, due to the clinical and genetic overlap of HH and CH; these genes may also be involved in the pathogenesis of CH. Using a candidate gene approach, we screened 156 Brazilian patients with combined pituitary hormone deficiencies (CPHD) for loss-of-function mutations in FGFR1 and PROKR2. We identified three FGFR1 variants (p.Arg448Trp, p.Ser107Leu and p.Pro772Ser) in four unrelated patients (two males) and two PROKR2 variants (p.Arg85Cys and p.Arg248Glu) in two unrelated female patients. Five of the six patients harbouring the variants had a first-degree relative that was an unaffected carrier of it. Results of functional studies indicated that the new FGFR1 variant p.Arg448Trp is a loss-of-function variant, while p.Ser107Leu and p.Pro772Ser present signalling activity similar to the wild-type form. Regarding PROKR2 variants, results from previous functional studies indicated that p.Arg85Cys moderately compromises receptor signalling through both MAPK and Ca(2) (+) pathways while p.Arg248Glu decreases calcium mobilization but has normal MAPK activity. The presence of loss-of-function variants of FGFR1 and PROKR2 in our patients with CPHD is indicative of an adjuvant and/or modifier effect of these rare variants on the phenotype. The presence of the same variants in unaffected relatives implies that they cannot solely cause the phenotype. Other associated genetic and/or environmental modifiers may play a role in the aetiology of this condition