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

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

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

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

A new bioactive glass/collagen hybrid composite for applications in dentistry

Bioactive glasses (BGs) are currently employed in a wide range of medical and dentistry applications by virtue of their bone-bonding ability. The incorporation of BGs into a collagen matrix may be used to combine the regenerative potential of these materials with the specific biological advantages of collagen. However, most of the collagen/BG composites reported in the literature are scaffolds and there is a lack of moldable putties or injectable systems. Here, granules of an innovative BG containing strontium and magnesium were mixed with collagen and PEG to obtain a putty (BGMS/C) suitable for dental applications. For the sake of comparison, granules of 45S5 Bioglass\uae, the gold standard among BGs, were used to prepare a 45S5/collagen putty. Both the composites were evaluated in vitro with respect to murine fibroblasts. The materials showed an excellent biocompatibility, making them interesting for possible applications in dentistry and reconstructive surgery. Moreover, BGMS/C seems to stimulate cell proliferation.Bioactive glasses (BGs) are currently employed in a wide range of medical and dentistry applications by virtue of their bone-bonding ability. The incorporation of BGs into a collagen matrix may be used to combine the regenerative potential of these materials with the specific biological advantages of collagen. However, most of the collagen/BG composites reported in the literature are scaffolds and there is a lack of moldable putties or injectable systems. Here, granules of an innovative BG containing strontium and magnesium were mixed with collagen and PEG to obtain a putty (BGMS/C) suitable for dental applications. For the sake of comparison, granules of 45S5 Bioglass\uae, the gold standard among BGs, were used to prepare a 45S5/collagen putty. Both the composites were evaluated in vitro with respect to murine fibroblasts. The materials showed an excellent biocompatibility, making them interesting for possible applications in dentistry and reconstructive surgery. Moreover, BGMS/C seems to stimulate cell proliferation

A Multi-Physic Modelling Insight into the Differences between Microwave and Conventional Heating for the Synthesis of TiO2 Nanoparticles

Microwave-assisted synthesis of nanoparticles usually leads to a smaller and more uni-formly distributed particle size compared to conventional heating (e.g., oil bath). Numerical simulation can help to obtain a better insight into the process in terms of temperature distribution or to evidence existing different temperature profiles and heating rates between the two techniques. In this paper multi-physics numerical simulation is used to investigate the continuous flow synthesis of titanium oxide nanoparticles starting from alkoxide precursors. Temperature-dependent permit-tivity of reactants has been measured, including the effects of permanence at the maximum synthesis temperature. A temperature homogeneity index has been defined to compare microwave and conventional heating. Results show that when using microwave heating at 2450 MHz, in the inves-tigated conditions, a much higher temperature homogeneity of the reactants is reached. Moreover, reactants experience different heating rates, depending on their position inside the microwave ap-plicator, while this is almost negligible in the case of conventional heating

The Khartoum-Omdurman conurbation : a growing megacity at the confluence of the Blue and White Nile Rivers

Khartoum is one of the largest cities in Africa, located immediately south of the junction of the Blue and White Nile rivers in central Sudan. The growth of the Greater Khartoum-Omdurman conurbation arose \uac\u2013 without a proper urban plan \u2013 from the agricultural wealth created through the completion of three major dams in 1925, 1937 and 1966, and mostly in the last three decades. Urban expansion was enabled by and helped to enhance the major agricultural expansion of the Gezira clay plains located to the south between the lower Blue and White Nile rivers. The confluence of the Blue and White Nile has been a focus of human settlement for at least 8,000 years, initially by semi-sedentary groups with a fishing-hunting-gathering lifestyle and later by Neolithic groups as shown by hundreds of archaeological sites. Today, Khartoum is a desert city and the hottest capital city on Earth, still very vulnerable to floods triggered by intense convectional storms. Such extreme events may become more common in future, representing a major geomorphological hazard in a city developed without urban plans. Moreover, uncontrolled urban and agricultural development is threatening most of the prehistoric cultural heritage of the region

Effect of galactooligosaccharides delivered in ovo on meat quality traits of broiler chickens exposed to heat stress

ABSTRACT: A study was carried out to evaluate meat quality traits in fast-growing chickens stimulated in ovo with trans-galactoolighosaccarides (GOS) and exposed to heat stress. On day 12 of egg incubation, 3,000 fertilized eggs (Ross 308) were divided into prebiotic group (GOS) injected with 3.5 mg GOS/egg, saline group (S) injected with physiological saline, and control group (C) uninjected. After hatching, 900 male chicks (300 chicks/treatment) were reared in floor pens in either thermoneutral (TN; 6 pens/group, 25 birds/pen) or heat stress conditions (HS, 30°C from 32 to 42 D; 6 pens/group, 25 birds/pen). At 42 D of age, 15 randomly chosen birds/treatment/temperature were slaughtered and the pectoral muscle (PM) was removed for analyses. Data were analyzed by GLM in a 3 × 2 factorial design. In ovo treatment had no effect on PM weight, pH, water-holding capacity, and shear force. GOS and S birds had lighter (L*, P < 0.01) PM than C group, whereas the latter showed a higher (P < 0.05) yellowness index (b*) compared to S group. Proximate composition, cholesterol, and intramuscular collagen properties were not affected by treatment. As for fatty acid composition, only total polyunsaturated fatty acids (PUFA) content and n-6 PUFA were slightly lower in GOS group compared to S. Heat stress had a detrimental effect on PM weight (P < 0.01) and increased meat pH (P < 0.01). PM from HS chickens was darker with a higher b* index (P < 0.05) and had a higher (P < 0.01) lipid content and a lower (P < 0.05) total collagen amount. Total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and PUFA were similar among groups. Significant interactions between factors were found for fatty acid composition: GOS decreased (P < 0.01) SFA and increased (P < 0.05) MUFA contents in HS birds. In conclusion, in ovo injection of GOS could mitigate the detrimental effect of heat stress on some meat quality traits