Hadronic Decays of Baryons in Point-Form Relativistic Quantum Mechanics

We discuss strong decays of baryon resonances within the concept of relativistic constituent quark models. In particular, we follow a Poincare-invariant approach along the point form of relativistic quantum mechanics. Here, we focus on pionic decay modes of N and Delta resonances. It is found that the covariant quark-model predictions calculated in the point-form spectator model in general underestimate the experimental data considerably. This points to a systematic defect in the used decay operator and/or the baryon wave functions. From a detailed investigation of the point-form decay operator it is seen that the requirement of translational invariance implies effective many-body contributions. Furthermore, one has to employ a normalization factor in the definition of the decay operator in the point-form spectator model. Our analysis suggests that this normalization factor is best chosen consistently with the one used for the electromagnetic and axial current operators for elastic nucleon form factors.Comment: 8 pages, 6 figures, presented at the "X Convegno su Problemi di Fisica Nucleare Teorica", Cortona, Italy, 6-9 Oct. 200

Electromagnetic nucleon form factors in instant and point form

We present a study of the electromagnetic structure of the nucleons with constituent quark models in the framework of relativistic quantum mechanics. In particular, we address the construction of spectator-model currents in the instant and point forms. Corresponding results for the elastic nucleon electromagnetic form factors as well as charge radii and magnetic moments are presented. We also compare results obtained by different realistic nucleon wave functions stemming from alternative constituent quark models. Finally, we discuss the theoretical uncertainties that reside in the construction of spectator-model transition operators.Comment: 13 pages, 9 figures, updated and extended version for publicatio

Isoscalar off-shell effects in threshold pion production from pd collisions

We test the presence of pion-nucleon isoscalar off-shell effects in the $pd\to \pi^+ t$ reaction around the threshold region. We find that these effects significantly modify the production cross section and that they may provide the missing strength needed to reproduce the data at threshold.Comment: 6 pages, REVTeX, twocolumn, including 3 figures (Postscript), uses psfig, updated and extended versio

Why is the three-nucleon force so odd?

By considering a class of diagrams which has been overlooked also in the most recent literature on three-body forces, we extract a new contribution to the three-nucleon interaction which specifically acts on the triplet odd states of the two nucleon subsystem. In the static approximation, this 3N-force contribution is fixed by the underlying 2N interaction, so in principle there are no free parameters to adjust. The 2N amplitude however enters in the 3NF diagram in a form which cannot be directly accessed or constrained by NN phase-shift analysis. We conclude that this new 3N-force contribution provides a mechanism which implies that the presence of the third nucleon modifies the p-wave (and possibly the f-wave) components of the 2N subsystem in the triplet-isotriplet channels.Comment: 10 Pages, 7 figures, RevTeX, twocolumn, epsf (updated version with minor changes

Enforcement and compliance: critical practices for community rehabilitation companies and the new NPS?

Efforts to secure compliance have always been a core element of probation practice,although compliance has been constructed in diverse ways and promoted through different means throughout its history. This article takes a brief historical perspective and reviews recent research on enforcement practices and developing understandings of compliance. These guide a critical discussion of the practices that might develop as responsibilities for enforcement are divided between the new National Probation Service (NPS) and Community Rehabilitation Companies (CRCs) under the Transforming Rehabilitation agenda, highlighting inevitable tensions and challenges, and anticipating how inter-agency practices might shape the ongoing construction of compliance. Charging more than one agency with responsibilities in relation to enforcement is tricky and creates risks in terms of legitimacy, credibility and justice. On the whole, future prospects seem difficult, but not hopeless and, in particular, there are examples of positive practices in probation and youth justice for the NPS and CRCs to draw upon as they develop their inter-agency structures and processes. Elsewhere, initiatives in problem-solving courts, focused, for example, on drug users, may also give indicators of constructive ways forwar

Management of mineral metabolism in hemodialysis patients: discrepancy between interventions and perceived causes of failure

none8BACKGROUND: Mineral and bone disorders (MBD) in patients undergoing hemodialysis (HD) are a major clinical complication. Current therapeutic strategies do not attain the expected results. The Italian audit on mineral metabolism was implemented to investigate MBD management through a "patient-oriented" approach. METHODS: Clinical and laboratory data pertinent to MBD from 509 prevalent adult patients on chronic HD were recorded and examined (audit), after which individual strategies were elaborated to improve MBD control. Their effectiveness was evaluated 6 months after the audit (Post-6). RESULTS: The audit disclosed poor MBD control in a high percentage of patients (56 %). Low compliance to treatment was the major determinant of failure (in 43.5 % of cases). Logistic regression showed a direct correlation between high degree of compliance and the achievement of therapeutic targets, e.g. parathyroid hormone: odds ratio (OR) 2.48, p = 0.015. In contrast, a minority of the proposed interventions (14.7 %) included strategies to improve patient compliance. At Post-6, despite a significant increase in drug prescription (p < 0.05 vs. audit), the rate of successful MBD control was unchanged. CONCLUSIONS: Low compliance with treatment is a major, but still neglected, cause of failure in the achievement of MBD control in HD patients.Esposito, P; Rampino, T; Gregorini, M; Tinelli, C; De Silvestri, A; Malberti, F; Coppo, R; Dal Canton, A.Esposito, P; Rampino, Teresa; Gregorini, Marilena; Tinelli, C; De Silvestri, A; Malberti, F; Coppo, R; DAL CANTON, Antoni

Colonização micorrízica e crescimento da videira (Vitis vinifera, Porta-Enxerto P1103) em solo com alto teor de cobre.

A aplicação de fungicidas cúpricos em vinhedos aumenta o teor de Cu no solo, potencializando a toxidez para a videira. Entretanto, tem sido relatado que os fungos micorrízicos arbusculares (FMA) podem propiciar efeito protetor às plantas em solos contendo excesso de metais pesados. O trabalho objetivou avaliar a colonização micorrízica e o crescimento da videira (porta-enxerto P1103) em solo contendo elevados teores de Cu. Avaliou-se seis tratamentos de inoculação com FMA (Dentiscutata heterogama, Gigaspora gigantea, Acaulospora morrowiae, A. colombiana, Rhizophagus clarus e R. irregularis), além de um não inoculado. Verificou-se que a colonização micorrízica da videira foi elevada (média de 33%), mesmo em solo contendo excesso de Cu. A inoculação dos isolados de FMA testados pouco influenciou o crescimento da videira, mas a inoculação com R. irregulares e R. clarus beneficiou a produção de massa seca das raízes das mudas.Resumo expandido