One-loop effective potential in M4 x T2 with and without 't Hooft flux

We review the basic notions of compactification in the presence of a background flux. In extra-dimentional models with more than five dimensions, Scherk and Schwarz boundary conditions have to satisfy 't Hooft consistency conditions. Different vacuum configurations can be obtained, depending whether trivial or non-trivial 't Hooft flux is considered. The presence of the "magnetic" background flux provide, in addition, a mechanism for producing four-dimensional chiral fermions. Particularizing to the six-dimensional case, we calculate the one-loop effective potential for a U(N) gauge theory on M4 x T2. We firstly review the well known results of the trivial 't Hooft flux case, where one-loop contributions produce the usual Hosotani dynamical symmetry breaking. Finally we applied our result for describing, for the first time, the one-loop contributions in the non-trivial 't Hooft flux case

Validity and reliability of the Italian version of the Oral Assessment Guide

Mucositis is a frequent side-effect of chemotherapy and radiotherapy. Assessment of oral cavity is important to detect alterations in the mouth and plan appropriate interventions. A reliable tool can help to have a better assessment of mucositis and a major knowledge about this phenomenon. Since no valid and reliable tool for the assessment of mucositis is still available in Italy, the aim of this study was to establish the validity and reliability of the Italian version of the Oral Assessment Guide (OAG). A panel of health care experts established the content validity of the tool both for the items and the descriptors. To establish the reliability of the tool, a sample of 14 inpatients with haematological diseases were recruited. Couples of dental hygienists separately performed 60 pairs of assessments (for a total of 120 assessments) on the sample. The Italian version of OAG was found to have an acceptable Content Validity Index (CVI) for items and related descriptors ranging between 0.67 and 1. Cronbach’s alpha was 0.84, agreement of assessment ranged between 0.87 and 0.65 with Cohen’s Kappa coefficient ranging from good to very good. This study showed that the Italian version of the OAG has good psychometric properties of validity and reliability to assess mucositis in patients undergoing chemotherapy. This tool will have a great importance to carry out future research in Italy aimed to improve the patient's outcomes particularly in terms of functional ability and quality of life

Preliminary study on a kinetic energy recovery system for sailing yachts

This paper presents the preliminary theoretical results obtained on a model of a kinetic energy recovery system for sailing yachts, based on the conversion of wave-induced boat oscillations (heave, pitch and roll) into electric energy by means of a linear generator. The recovery system is based on a linear generator, with a mass oscillating along the vertical axis and gaining kinetic energy: the resulting mechanical energy can be extracted (by means of electromagnetic damping) and converted into electricity. The oscillating mass incorporates permanent magnets which, moving in proximity of stator windings, generate electric power due to electromagnetic induction. The device aims at recovering as much kinetic energy as possible from the natural movements of a sailing yacht on the sea, therefore taking the view of a boat as a moving wave energy converter with energy harvesting capability. The boat's motions can be vertical oscillations due to the buoyancy in the presence of sea waves, both when the boat is still or sailing, and rolling and pitching motions originated both by sailing in wavy waters and by the normal boat dynamics due to the sails' propulsion. Linear generators will convert kinetic energy into electrical energy to be used as “green” electricity for any possible application on board. Preliminary calculations show that a properly configured system could be able to recover approximately 100 W under most sea conditions on an almost continuous basis, which can be an extremely attractive result since an electric energy availability of 1–2 kWh on a sailing yacht is of significant interest

Minimal gauge-Higgs unification with a flavour symmetry

We show that a flavour symmetry a la Froggatt-Nielsen can be naturally incorporated in models with gauge-Higgs unification, by exploiting the heavy fermions that are anyhow needed to realize realistic Yukawa couplings. The case of the minimal five-dimensional model, in which the SU(2)_L x U(1)_Y electroweak group is enlarged to an SU(3)_W group, and then broken to U(1)_em by the combination of an orbifold projection and a Scherk-Schwarz twist, is studied in detail. We show that the minimal way of incorporating a U(1)_F flavour symmetry is to enlarge it to an SU(2)_F group, which is then completely broken by the same orbifold projection and Scherk-Schwarz twist. The general features of this construction, where ordinary fermions live on the branes defined by the orbifold fixed-points and messenger fermions live in the bulk, are compared to those of ordinary four-dimensional flavour models, and some explicit examples are constructed.Comment: LaTex, 37 pages, 2 figures; some clarifying comments and a few references adde

Phenomenology of symmetry breaking from extra dimensions

Motivated by the electroweak hierarchy problem, we consider theories with two extra dimensions in which the four-dimensional scalar fields are components of gauge boson in full space. We explore the Nielsen-Olesen instability for SU(N) on a torus, in the presence of a magnetic background. A field theory approach is developed, computing explicitly the minimum of the complete effective potential, including tri-linear and quartic couplings and determining the symmetries of the stable vacua. We also develop appropriate gauge-fixing terms when both Kaluza-Klein and Landau levels are present and interacting, discussing the interplay between the possible six and four dimensional choices. The equivalence between coordinate dependent and constant Scherk-Schwarz boundary conditions -associated to either continuous or discrete Wilson lines- is analyzed.Comment: 39 pages and 8 eps figures. Few changes in section

Capsule impaction presenting as acute small bowel perforation: a case series

INTRODUCTION: Perforation caused by capsule endoscopy impaction is extremely rare and, at present, only five cases of perforation from capsule endoscopy impaction are reported in the literature. CASE PRESENTATION: We report here two cases of patients with undiagnosed small bowel stenosis presenting with acute perforation after capsule endoscopy. Strictures in the small bowel were likely the inciting mechanism leading to acute small bowel obstruction and subsequent distension and perforation above the capsule in the area of maximal serosal tension. Case 1 was a 55-year-old Italian woman who underwent capsule endoscopy because of recurrent postprandial cramping pain and iron deficiency anemia, in the setting of negative imaging studies including an abdominal ultrasound, upper endoscopy, colonoscopy and small bowel follow-through radiograph. She developed a symptomatic bowel obstruction approximately 36 hours after ingestion of the capsule. Emergent surgery was performed to remove the capsule, which was impacted at a stenosis due to a previously undiagnosed ileal adenocarcinoma, leading to perforation. Case 2 was a 60-year-old Italian man with recurrent episodes of abdominal pain and diarrhea who underwent capsule endoscopy after conventional modalities, including comprehensive blood and stool studies, computed tomography, an abdominal ultrasound, upper endoscopy, colonoscopy, barium enema and small bowel follow-through, were not diagnostic. Our patient developed abdominal distension, acute periumbilical pain, fever and leukocytosis 20 hours after capsule ingestion. Emergent surgery was performed to remove the capsule, which was impacted at a previously undiagnosed ileal Crohn’s stricture, leading to perforation. CONCLUSIONS: The present report shows that, although the risk of acute complication is very low, the patient should be informed of the risks involved in capsule endoscopy, including the need for emergency surgical exploration

Phase Transitions on Nonamenable Graphs

We survey known results about phase transitions in various models of statistical physics when the underlying space is a nonamenable graph. Most attention is devoted to transitive graphs and trees