Search results for "URL"
showing 10 items of 539 documents
Individuazione dei trend di pioggia per la Sicilia utilizzando un approccio multiscala basato sulla regressione a quantili
2021
Uno degli argomenti più attuali e controversi è se, negli ultimi decenni, le piogge intense siano diventate più frequenti come possibile effetto dei cambiamenti climatici. La centralità del tema è giustificata dalle gravi conseguenze che l’intensificarsi di questi fenomeni, in frequenza e magnitudo, potrebbe indurre a livello sociale ed economico. Basti pensare alle “flash flood”, spesso causate da eventi di precipitazione con una forte componente convettiva, che in ambito urbano mettono in crisi i sistemi di drenaggio arrecando rilevanti danni e, purtroppo, anche perdite di vite umane. La Sicilia è stata spesso monitorata con l’obiettivo di individuare delle mutazioni significative del cic…
Medium effects in DIS from polarized nuclear targets
2014
The behavior of the nucleon structure functions in lepton nuclei deep inelastic scattering, both polarized and unpolarized, due to nuclear structure effects is reanalyzed. The study is performed in two schemes: an x-rescaling approach, and one in which there is an increase of sea quark components in the in medium nucleon, related to the low energy N-N interaction. In view of a recent interesting experimental proposal to study the behavior of the proton spin structure functions in nuclei we proceed to compare these approaches in an effort to enlighten the possible phenomenological interest of such difficult experiment.
The triple collinear limit of one-loop QCD amplitudes
2003
We consider the singular behaviour of one-loop QCD matrix elements when several external partons become simultaneously parallel. We present a new factorization formula that describes the singular collinear behaviour directly in colour space. The collinear singularities are embodied in process-independent splitting matrices that depend on the momenta, flavours, spins and colours of the collinear partons. We give the general structure of the infrared and ultraviolet divergences of the one-loop splitting matrices. We also present explicit one-loop results for the triple collinear splitting, $q \to q {\bar Q} Q$, of a quark and a quark--antiquark pair of different flavours. The one-loop triple …
The pion distribution amplitude and the pion-photon transition form factor in a nonlocal chiral quark model
2014
We study the pion Distribution Amplitude (\pi DA) in the context of a nonlocal chiral quark model. The corresponding Lagrangian reproduces the phenomenological values of the pion mass and decay constant, as well as the momentum dependence of the quark propagator obtained in lattice calculations. It is found that the obtained \pi DA has two symmetric maxima, which arise from the new contributions generated by the nonlocal character of the interactions. This \pi DA is applied to leading order and next-to-leading order calculations of the pion-photon transition form factor. Implications of the results are discussed.
Form factors of radiative pion decays in nonlocal chiral quark models
2012
We study the radiative pion decay π +→e +ν eγ within nonlocal chiral quark models that include wave function renormalization. In this framework we analyze the momentum dependence of the vector form factor F V(q2) and the slope of the axial-vector form factor F A(q2) at threshold. Our results are compared with available experimental information and with the predictions given by the Nambu-Jona-Lasinio model. In addition we calculate the low energy constants δ 5 and δ 6, comparing our results with the values obtained in chiral perturbation theory.
Perturbative generation of a strange-quark asymmetry in the nucleon
2004
We point out that perturbative evolution in QCD at three loops generates a strange-antistrange asymmetry s(x)-sbar(x) in the nucleon's sea just from the fact that the nucleon has non-vanishing up and down quark valence densities. The recently computed three-loop splitting functions allow for an estimate of this effect. We find that a fairly sizable asymmetry may be generated. Results for analogous asymmetries in the heavy-quark sector are also presented.
Switching nuclearity and Co(II) content through stoichiometry adjustment: {Co(II)6Co(III)3} and {Co(II)Co4(III)} mixed valent complexes and a study o…
2015
We are reporting two new mixed valent Co(ii)/Co(iii) polynuclear complexes, {Co II 6 Co III 3 } and {Co II Co III 4 }, bearing different amount of Co(ii) ions in their cores, through the employment of the multidentate triethanolamine (teaH 3 ) ligand in different stoichiometric ratios. We present a complete picture of the magnetic behaviour of both complexes through a combined usage of the susceptibility, magnetization and X-band EPR data as well as broken-symmetry DFT calculations. Compound 1 shows an atypical spin-only behaviour, probably due to the presence of four and five coordinated Co(ii) sites as well as highly distorted six coordinated Co(ii) ions, promoting a high degree of orbita…
Aporocotyle mariachristinae n. sp., and A. ymakara VillalbaFernández, 1986 (Digenea: Aporocotylidae) of the pink cusk-eel, Genypterus blacodes (Ophid…
2012
Aporocotyle mariachristinae n. sp. and A. ymakara Villalba & Fernández, 1986 were collected from the bulbus arteriosus and ventral aorta of pink cusk-eels, Genypterus blacodes (Forster, 1801) from Patagonia, Argentina. A. mariachristinae n. sp. can be distinguished from all the species of Aporocotyle by the asymmetrical extension of posterior caeca (right posterior caecum longer, terminating at the area between mid-level of ovary and posterior body end; left posterior caecum shorter, terminating at the area between mid-level of cirrus sac and posterior to reproductive organs), the distribution of spines along the ventro-lateral body margins and the number of testes. The new species clearly …
Women's connective action: Analysis of the mobilization of the #ParoInternacionalDeMujeres of March 8, 2017
2020
Este artículo presenta un análisis del modo de manifestarse y de las percepciones de las/ os participantes en el #ParoInternacionalDeMujeres que tuvo lugar el 8 de marzo de 2017 en Argentina. Su hipótesis sostiene que la movilización mostró una lógica de acción conectiva híbrida. La investigación que sustenta este trabajo consistió en la realización de una encuesta en el momento y lugar de la movilización, a un total de 365 personas, con el propósito de capturar la percepción de las/os participantes y no simplemente de las/os impulsoras/es. Los datos resultantes de la encuesta se interpretaron considerando cinco dimensiones analíticas creadas a partir del concepto de acción conectiva: carác…
Noraksti no Kurzemes hercogistes un Livonijas likumu krājumiem, 1606.-1698. gada dokumenti [Mietausche Policeÿ Ordnung von Anno 1606. 5. Septembris]
1698
Nosaukums pirmajā lapā: Mietausche Policeÿ Ordnung von Anno 1606. 5. Septembris