Twist Three Distribution f_\perp(x,k^\perp) in Light-front Hamiltonian Approach

We calculate the twist three distribution f_\perp(x,k^\perp) contributing to Cahn effect in unpolarized semi-inclusive deep inelastic scattering. We use light-front Hamiltonian technique and take the state to be a dressed quark at one loop in perturbation theory. The 'genuine twist three' contribution comes from the quark-gluon interaction part in the operator and is explicitly calculated. f_\perp(x,k^\perp) is compared with f_1(x,k^\perp).Comment: Two figures added, one author added, some parts rewritten for clarificatio

Semi-inclusive structure functions in the spectator model

We establish the relationship between distribution and fragmentation functions and the structure functions appearing in the cross section of polarized 1-particle inclusive deep-inelastic scattering. We present spectator model evaluations of these structure functions focusing on the case of an outgoing spin-1/2 baryon. Distribution functions obtained in the spectator model are known to fairly agree at low energy scales with global parameterizations extracted, for instance, from totally inclusive DIS data. Therefore, we expect it to give good hints on the functional dependence of the structure functions on the scaling variables x(Bjorken), z and on the transverse momentum of the observed outgoing hadron, P_{h\perp}. Presently, this dependence is not very well known, but experiments are planned in the near future.Comment: 19 pages, 16 figures, submitted to Eur. Phys. J.

Estimate of the Collins function in a chiral invariant approach

We estimate the Collins function at a low energy scale by calculating the fragmentation of a quark into a pion at the one-loop level in the chiral invariant model of Manohar and Georgi. We give a useful parametrization of our results and we briefly discuss different spin and/or azimuthal asymmetries containing the Collins function and measurable in semi-inclusive DIS and e+ e- annihilationComment: 5 pages, 4 figures, to appear in Proceedings of 10th International Workshop on Deep Inelastic Scattering (DIS 2002), Cracow, Poland, 30 Apr-4 May 200

La flora del Monte Arcuentu (Sardegna sud occidentale)

The results of an anaytical survey of the flora of Monte Arcuentu, a volcanic massif in SW Sardinia, are reported. The survey resulted in 556 recorded taxa, belonging to 335 genus, 84 families and 39 orders. The most represented Phylum is Magnoliophyta (539 taxa), of which the Eudicots represent the richest systematic group, with 22 orders, 54 families and 405 species. The most represented orders are: Asterales (74 taxa), Lamiales (59), Fabales (53) and Caryophyllales (30). Most of the recored taxa were belonging to Asteraceae (71), followed by Fabaceae (52) and Poaceae (51). Most frequent genera are: Trifolium (11), Euphorbia (9), Allium, Geranium, Juncus, Medicago, Ophrys, Orobanche (7). The biological spectrum highlights the remarkable Mediterranean connotation of the studied district, being the therophytes (40.8%), followed by hemicriptophytes (27.0%) and geophytes (14.7%) being the most frequent growth forms. Indeed, the chorologic spectrum is dominated by the Mediterranean chorotype (48.4%), whose main partitions are: steno-Mediterranean (22.8%), endemic (9.7%) and W-Medit. (9.3%). Taxa with a broader distribution range, but centred in the Mediterranean basin, represent the 26.6%. The endemic taxa were 54 , among which Asteraceae (8) and Fabaceae (5) were the most represented families. The chorologic spectrum of the endemic units is dominated by Sardo-Corsican taxa (20), followed by Italo-Tyrrhenian ones (14). The analysis of rarity, according to the categories of Rabinowitz, highlighted the fact that the largest group (231) consists of WBL (i.e. species diffused over the territory, with a wide ecology and a large local population, in some places dominant), while the smallest one (5) is formed by the NBL (i.e. species with a limited spread over the territory, a wide ecology and a large local population, at times dominant). The taxa protected by international regulations are all the recorded orchids (19) and Cyclamen repandum subsp. repandum, included in the attached II of CITES, Brassica insularis in the Berne Convention, 2 in the Habitat Directive (Brassica insularis and Ruscus aculeatus), plus 3 (Soleirolia soleirolii, Hyoseris taurina and Genista morisii) cited in the IUCN- red lists

Successful pulmonary thromboendarterectomy in a patient with sickle cell disease and associated resolution of a leg ulcer

© 2017 Indian Chest Society | Published by Wolters Kluwer -Medknow. Pulmonary hypertension (PH) is a relatively frequent and severe complication of sickle cell disease (SCD). PH associated with SCD is classified as Group 5 PH. The exact pathogenesis of PH in SCD in not known. There are also very limited treatment options available at this time for such patients with Group 5 PH. Patients with SCD are predisposed to a hypercoagulable state and thus can also suffer from chronic thromboembolism. These patients can have associated chronic thromboembolic pulmonary hypertension (CTEPH), thus being classified as Group 4 PH. We present such a case of a patient with SCD diagnosed with severe PH who was found to have CTEPH and successfully underwent a thromboendarterectomy with resolution of his symptoms such as reduction of his oxygen requirements and healing of chronic leg ulcer. This case illustrates the importance of screening patients with SCD and elevated pulmonary artery pressures for CTEPH as this would offer possible treatment options such as pulmonary thromboendarterectomy and/or riociguat in this subset of patients

Weighted azimuthal asymmetries in a diquark spectator model

We analytically calculate weighted azimuthal asymmetries in semi-inclusive lepton-nucleon deep-inelastic scattering and Drell-Yan processes, using transverse-momentum-dependent partonic densities obtained in a diquark spectator model. We compare the asymmetries with available preliminary experimental data, in particular for the Collins and the Sivers effect. We make predictions for other cases of interest in running and planned experiments.Comment: 21 pages, 13 (multiple) figures in eps format, RevTeX

Generalized parton correlation functions for a spin-1/2 hadron

The fully unintegrated, off-diagonal quark-quark correlator for a spin-1/2 hadron is parameterized in terms of so-called generalized parton correlation functions. Such objects, in particular, can be considered as mother distributions of generalized parton distributions on the one hand and transverse momentum dependent parton distributions on the other. Therefore, our study provides new, model-independent insights into the recently proposed nontrivial relations between generalized and transverse momentum dependent parton distributions. We find that none of these relations can be promoted to a model-independent status. As a by-product we obtain the first complete classification of generalized parton distributions beyond leading twist. The present paper is a natural extension of our previous corresponding analysis for spin-0 hadrons.Comment: 41 pages, 3 figures; v2: added referenc

Estimate of the Collins fragmentation function in a chiral invariant approach

We predict the features of the Collins function, which describes the fragmentation of a transversely polarized quark into an unpolarized hadron, by modeling the fragmentation process at a low energy scale. We use the chiral invariant approach of Manohar and Georgi, where constituent quarks and Goldstone bosons are considered as effective degrees of freedom in the non-perturbative regime of QCD. To test the approach we calculate the unpolarized fragmentation function and the transverse momentum distribution of a produced hadron, both of which are described reasonably well. In the case of semi-inclusive deep-inelastic scattering, our estimate of the Collins function in connection with the transversity distribution gives rise to a transverse single spin asymmetry of the order of 10%, supporting the idea of measuring the transversity distribution of the nucleon in this way. In the case of e+ e- annihilation into two hadrons, our model predicts a Collins azimuthal asymmetry of about 5%.Comment: 12 pages, 15 figures. Figs. 11-14 changed, minor changes in discussion, few typos fixed and some references added. Final version to appear in PR

A phytosociological study of the deciduous oak woods of Sardinia (Italy)

We present here the results from a phytosociological and synchorological study of the deciduous oak woods of Sardinia. This vegetation analysis has allowed the individuation of three new associations: Lonicero implexae-Quercetum virgilianae, Ornithogalo pyrenaici-Quercetum ichnusae and Glechomo sardoae-Quercetum congestae. The Lonicero implexae-Quercetum virgilianae association includes the woods on calcareous substrata spread throughout Northern Sardinia, which can occasionally be found in southern areas; the first of these are rich in mesophilous species and are attributed to the subassociation cyclaminetosum repandi, while the others are referred to quercetosum virgilianae. The Ornithogalo pyrenaici-Quercetum ichnusae association, more widely distributed in Central-Northern Sardinia, includes the climatophilous deciduous woods that are found on lithological substrata of a non-carbonatic nature, and in particular, on andesites, trachytes and metarenites. The typical aspect is referred to the subassociation cytisetosum villosi, while the subassociation ilicetosum aquifolii includes the more mesophilous woods on basaltic substrata. The Glechomo sardoae- Quercetum congestae association always includes the woods found on the non-carbonatic substrata in the higher altitude areas with an oceanic pluviseasonal temperate bioclimate. Of this, the subassociation quercetosum congestae, on the granite areas, and oenanthetosum pimpinelloidis, on those metamorphic and of basalt, are proposed. At the higher hierarchical levels, the association Lonicero implexae-Quercetum virgilianae is referred to the endemic Sardinian-Corsican suballiance Clematido cirrhosae-Quercenion ilicis, of the alliance Fraxino orni-Quercion ilicis, while for the other associations the new suballiance Paeonio morisii-Quercenion ichnusae, (holotypus: Glechoma sardoae-Quercetum congestae ass. nova) particular to the Sardinian biogeographic subprovince, is proposed, of the alliance Pino calabricae-Quercion congestae, the order Quercetalia pubescentipetraeae, and the class Querco roboris-Fagetea sylvaticae