Exploring the epsilon regime with lattice Wilson fermions

We study the impact of explicit chiral symmetry breaking of lattice Wilson fermions on mesonic correlators in the epsilon-regime using Wilson chiral perturbation theory. We generalize the epsilon-expansion of continuum chiral perturbation theory to nonzero lattice spacing a and distinguish various regimes. It turnes out that lattice corrections are highly suppressed, as long as quark masses are of the order a\Lambda^2_QCD. The lattice spacing effects become more pronounced for smaller quark masses and may lead to non-trivial corrections of the continuum results at next-to-leading order. We compute these corrections for standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.Comment: 8 pages, 1 figure. Presented at the International Workshop on Effective Field Theories: from the pion to the upsilon, February 2-6 2009, Valencia, Spai

The epsilon regime with Wilson fermions

We study the impact of explicit chiral symmetry breaking of Wilson fermions on mesonic correlators in the epsilon-regime using Wilson chiral perturbation theory (WChPT). We generalize the epsilon-expansion of continuum ChPT to nonzero lattice spacings for various quark mass regimes. It turns out that the corrections due to a nonzero lattice spacing are highly suppressed for typical quark masses of the order aLambda_QCD^2. The lattice spacing effects become more pronounced for smaller quark masses and lead to non-trivial corrections of the continuum ChPT results at next-to-leading order. We compute these corrections for the standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.Comment: 29 pages, 2 figure

Wilson fermions in the epsilon regime

We extend the epsilon-expansion of continuum chiral perturbation theory to nonzero lattice spacing in the framework of Wilson Chiral Perturbation Theory. We distinguish various regimes by defining the relative power counting of the quark mass m and the lattice spacing a. We observe that for m ~ a Lambda^2_QCD, the explicit breaking of chiral symmetry in Wilson fermions is still driven by the quark mass and lattice corrections are highly suppressed. The lattice spacing effects become more pronounced for smaller quark masses and may lead to non-trivial corrections of the continuum results at next-to-leading order. We compute these corrections for standard current and density correlation functions. A fit to lattice data shows that these corrections are small, as expected.Comment: Talk presented at the XXVII International Symposium on Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, China; 7 pages, 1 figur

Comparison of Accuracy and Reproducibility of Casts Made by Digital and Conventional Methods

Statement of problem Little peer-reviewed information is available regarding the accuracy and reproducibility of digitally fabricated casts compared to conventional nondigital methods. Purpose The purpose of this in vitro study was to compare the accuracy and reproducibility of a digital impression and cast fabrication with a conventional impression and cast fabrication. Material and methods Conventional impressions were made via a 1-step single viscosity technique with vinyl siloxanether material of a typodont master model, and conventional casts were cast from dental stone. Digital impressions were obtained with a digital scanner, and digital stereolithographic models were printed. The typodont and fabricated casts were digitized with a structured light scanner and saved in surface tessellation language (STL) format. All STL records were superimposed via a best-fit method. The digital impression and cast fabrication method was compared with the conventional impression and cast fabrication method for discrepancy, accuracy, and reproducibility. The Levene test was used to determine equality of variances, and a 1-way ANOVA was conducted to assess the overall statistical significance of differences among the groups (n=5, α=.05). Results No significant statistical difference was found between the digital cast and conventional casts in the internal area or finish line area (P\u3e.05). In addition, there was no statistically significant difference between these 2 techniques for a fixed dental prosthesis or single crown (P\u3e.05). However, statistically significant differences were observed for overall areas of the casts in terms of accuracy (PP Conclusions No statistically significant difference was found between the digital cast and conventional cast groups in the internal and finish line areas. However, in terms of the reproducibility and accuracy of the entire cast area, the conventional cast was significantly better than the digital cast

Quality of Postoperative Pain Management after Midfacial Fracture Repair—An Outcome-oriented Study

Objectives There is a lack of literature regarding the procedure-specific quality of acute postoperative pain management after midfacial fracture repair. The purpose of the presented prospective clinical study was to evaluate postoperative pain management after surgical repair of midfacial fractures. Materials and methods Eighty-five adults were evaluated on the first postoperative day following midfacial repair using the questionnaire of the Quality Improvement in Postoperative Pain Management (QUIPS) project. The main outcome measures were patients’ characteristics and clinical- and patient-reported outcome parameters. Results Overall, pain on the first postoperative day was moderate. A significant correlation between process and outcome parameters could be shown. Duration of surgery above the calculated median was significantly associated with higher maximum pain intensity (p = 0.017). Patients requiring opioids in the recovery room presented significantly higher pain on activity (p = 0.029) and maximum pain (p = 0.035). Sleeping impairment (p = 0.001) and mood disturbance (p = 0.008) were significantly more prevalent in patients undergoing repair of a centrolateral midfacial fracture. Conclusions QUIPS is a simple and qualified tool to evaluate the procedure specific quality of acute postoperative pain management. Pain on the first postoperative day following midfacial fracture repair seems overall to be moderate. Nearly a third of the patients showed inadequate postoperative pain management. To prevent inadequate postoperative pain management, it is necessary to establish a continued procedure-specific outcome measurement

Impact of treatment planning target volumen (PTV) size on radiation induced diarrhoea following selenium supplementation in gynecologic radiation oncology - a subgroup analysis of a multicenter, phase III trial

Background: In a previous analysis (Int J Radiat Oncol Biol Phys 70:828-835,2010), we assessed whether an adjuvant supplementation with selenium (Se) improves Se status and reduces the radiation-induced side-effects of patients treated by adjuvant radiotherapy (RT) for cervical and uterine cancer. Now, a potential relation between the planning target volume (PTV) of the RT and the Se effect concerning radiation induced diarrhoea was evaluated in detail. Methods: Whole blood Se concentrations had been measured in patients with cervical (n=11) and uterine cancer (n=70) after surgical treatment, during, and at the end of RT. Patients with initial Se concentrations of less than 84 μg/l were categorized as Se-deficient and randomized before RT to receive Se (as sodium selenite) per os on the days of RT, or to receive no supplement during RT. Diarrhoea was graded according to the Common Toxicity Criteria system (CTC, Version 2a). The evaluation of the PTV of the RT was ascertained with the help of a specialised computer-assisted treatment planning software used for radiation planning procedure. Results: A total of 81 patients had been randomized for the initial supplementation study, 39 of which received Se [selenium group, SeG] and 42 serving as controls [control group, CG]. Mean Se levels did not differ between SeG and CG upon study initiation, but were significantly higher in the SeG compared to the CG at the end of RT. The actuarial incidence of at least CTC 2 radiation induced diarrhoea in the SeG was 20.5% compared to 44.5% in the CG (p=0.04). The median PTV in both groups was 1302 ml (916–4608). With a PTV of 1302 ml (n=40) the actuarial incidence of at least CTC 2 diarrhoea in the SeG was 19.1% (4 of 21 patients) versus 52.6% (10 of 19 patients) in the CG (p=0.046). Conclusions: Se supplementation during RT was effective to improve blood Se status in Se-deficient cervical and uterine cancer patients, and reduces episodes and severity of RT-induced diarrhoea. This effect was most pronounced and significant in patients with large PTV (> 1302 ml)