Consistency Condition for the Pinch Technique Self-Energies at Two Loops

A simple and testable necessary condition for the gauge independence of the Pinch Technique self-energies at two loops is discussed. It is then shown that, in the case of the $Z$ and $W$ self-energies, the condition is indeed satisfied by the Papavassiliou-Pilaftsis formulation.Comment: 7 pages, Latex, 1 PostScript figur

Precise calculation of MW, sin^2 theta_MSbar, and sin^2 theta_eff

The two-loop O(g^4 mt^2/mw^2) corrections are incorporated in the theoretical calculation of MW, sin^2 theta_MSbar(MZ), and sin^2 theta_eff, as functions of MH. The analysis is carried out in a previously proposed MSbar formulation and two novel on-shell resummation schemes. It is found that the inclusion of the new effects sharply decreases the scheme and residual scale dependence of the calculations. QCD corrections are incorporated in two different approaches. Comparison with the world average of sin^2 theta_eff leads to MH= 127 +143 -71 GeV and MW= 80.367 +/- 0.048 GeV, with small variations among the six calculations.Comment: 10 pages, Latex, 3 table

Application of the Pinch Technique to Neutral Current Amplitudes and the Concept of the Z Mass

The pinch technique (PT) is applied to neutral current amplitudes, focusing on the mixing problem. Extending recent arguments due to Papavassiliou and Pilaftsis, it is shown that the use of the PT self-energies does not shift the complex-valued position of the pole through order {\cal O}($g^4$). This leads (to the same accuracy) to a simple interpretation of $M_Z$, the mass measured at LEP, in terms of the PT self-energies. It is pointed out that the PT approach provides a convenient and rather elegant formalism to discuss important neutral current amplitudes, such as those relevant to four-fermion processes and LEP2.Comment: 13 pages, Latex, 3 PostScript figure

Evidence for Bosonic Electroweak Corrections in the Standard Model

We present strong indirect evidence for the contribution of bosonic electroweak corrections in the Standard Model. Although important conceptually, these corrections give subleading contributions in current high energy experiments, and it was previously thought that they are difficult to detect. We also discuss the separate contribution of the Higgs boson.Comment: 9 pages (LaTeX + 3 PS figures, needs psfig

Renormalon contributions to \delta\rho

Leading QCD vacuum polarization contributions to the electroweak parameter $\delta\rho$ are evaluated numerically using several different prescriptions for the gluon self-energy. Simple theoretical estimates of the asymptotic behavior are given. The results show a significant contribution from the leading infrared renormalons when $\delta\rho$ is expressed in terms of the top-quark pole mass and its absence when the \msbar running mass is employed. The calculations are applied to estimate higher order QCD contributions to $\delta\rho$.Comment: 9 pages, plain late

Thirty Years of Precision Electroweak Physics

We discuss the development of the theory of electroweak radiative corrections and its role in testing the Standard Model, predicting the top quark mass, constraining the Higgs boson mass, and searching for deviations that may signal the presence of new physics.Comment: 19 pages, acknowledgments added, J.J.Sakurai Prize Talk, APS Meeting, Albuquerque, N.M., April 2002. To appear in a future issue of Journal of Physics

Is there a role for tumor volume in prediction of prognosis for oral cancer?

Purpose: New prognostic factors in oral squamous cell carcinoma (OSCC) (tumor-, host-, and environment-related) have been introduced recently to complete those traditionally considered. Among them, tumor volume (TV) could be the most interesting and applicable in clinical practice, considering the routine use of computed tomography in tumor staging. In this retrospective study we aimed to investigate whether a correlation exists among these new prognostic factors and survival outcomes. Meterials and methods: We collected data about 140 patients affected by OSCC who underwent primary surgery. Prognostic factors were collected and Overall Survival (OS), Disease Specific Survival (DSS) and Disease Free Survival (DFS) were estimated using Kaplan-Meier method; the Log-Rank test (Mantel-Cox) and Cox regression models were applied to investigate predictors of survival. Results: The 5-year OS, DSS and DFS were 73.6 %, 89.2 % and 75.2 % respectively. Nodal metastasis (pN+), relapse and American Society of Anesthesiologists ASA-II were found independent prognostic factors for OS, and significantly associated to worst DSS (p < 0.001). TV significantly correlated with higher relapse occurrence (p = 0.03). Conclusions: In our experience, lymph-node status, ASA classification and relapse significantly influenced DSS on univariate analysis. TV could represent an interesting additional parameter, since it significantly influenced DFS. However, prospective studies with standardized TV measurements and a greater number of patients are needed to validate this result

Prognostic role of the MRI-based involvement of superior pharyngeal constrictor muscle in oropharyngeal squamous cell carcinoma

Objectives: The aim of this study was to determine the impact of the involvement of the superior pharyngeal constrictor muscle (SPCM) evaluated by magnetic resonance imaging (MRI) on outcome in oropharyngeal squamous cell carcinomas (OPSCCs). Methods: A retrospective study including consecutive patients with OPSCC treated with curative intent. Results: A total of 82 consecutive patients with OPSCC met inclusion criteria. At multivariate analysis, patients with SPCM infiltration were at significantly higher risk of death (HR: 3.37, CI: 1.21-9.38) and progression (HR: 3.39, CI: 1.38-8.32). In a multivariate model conditioned on HPV status, a significantly higher risk of death and progression was observed by combining both SPCM and HPV status with patients harboring an HPV-negative OPSCC with SPCM infiltration showing the poorest outcome. Conclusion: MRI evidence of SPCM involvement significantly and independently increases the risk of death and progression in subjects with OPSCC. Considering both MRI-assessed SPCM infiltration and HPV status significantly improved risk stratification in these malignancies

Screening of bacterial endophytes as potential biocontrol agents against soybean diseases

Aims: This research was aimed at identifying and characterizing endophytic micro-organisms associated with soybean that have antimicrobial activity towards soybean pathogens. Methods and Results: Soybean plants were collected from field trials in four locations of southern Brazil that were cultivated with conventional (C) and transgenic glyphosate-resistant (GR) soybeans. Endophytic bacteria isolated from roots, stems and leaves of soybeans were evaluated for their capacity to inhibit fungal and bacterial plant pathogens and 13 micro-organisms were identified with antagonistic activity. Approximately 230 bacteria were isolated and identified based on the 16S rRNA and rpoN gene sequences. Bacteria isolated from conventional and transgenic soybeans were significantly different not only in population diversity but also in their antagonistic capacity. Thirteen isolates showed in vitro antagonism against Sclerotinia sclerotiorum, Phomopsis sojae and Rhizoctonia solani. Bacillus sp. and Burkholderia sp. were the most effective isolates in controlling bacterial and fungal pathogens in vitro. Extracts and precipitates from culture supernatants of isolates showed different patterns of inhibitory activity on growth of fungal and bacterial pathogens. Conclusions: Bacillus sp. and Burkholderia sp. were the most effective isolates in controlling fungal pathogens in vitro, and the activity is mainly due to peptides. However, most of the studied bacteria showed the presence of antimicrobial compounds in the culture supernatant, either peptides, bacteriocins or secondary metabolites. Significance and Impact of the Study: These results could be significant to develop tools for the biological control of soybean diseases. The work brought to the identification of micro-organisms such as Bacillus sp. and Burkholderia sp. that have the potential to protect crops in order to enhance a sustainable management system of crops. Furthermore, the study provides the first evidences of the influence of management as well as the genetics of glyphosate-resistant soybean on the diversity of bacterial endophytes of soybean phytobiome.Facultad de Ciencias Agrarias y Forestale

Incorporation of QCD Effects in Basic Corrections of the Electroweak Theory

We study the incorporation of QCD effects in the basic electroweak corrections \drcar, \drcarw, and \dr. They include perturbative \Ord{\alpha\alpha_s} contributions and $t\bar{t}$ threshold effects. The latter are studied in the resonance and Green-function approaches, in the framework of dispersion relations that automatically satisfy relevant Ward identities. Refinements in the treatment of the electroweak corrections, in both the \ms\ and the on-shell schemes of renormalization, are introduced, including the decoupling of the top quark in certain amplitudes, its effect on \hat{e}^2(\mz) and \sincarmz, the incorporation of recent results on the leading irreducible \Ord{\alpha^2} corrections, and simple expressions for the residual, i.e.\ ``non-electromagnetic'', parts of \drcar, \drcarw, and \dr. The results are used to obtain accurate values for \mw\ and \sincarmz, as functions of \mt\ and \mh. The higher-order effects induce shifts in these parameters comparable to the expected experimental accuracy, and they increase the prediction for \mt\ derived from current measurements. The \ms\ and the on-shell calculations of \dr, in a recently proposed formulation, are compared and found to be in excellent agreement over the wide ranges 60\GeV \leq \mh \leq 1 \TeV, \mz \leq \mt \leq 250 \GeV.Comment: 51 pages (needs doublespace, equations, and cite styles