Flavour transitions of Dirac-Majorana neutrinos

From a phenomenological point of view, we study active-active and active-sterile flavour-changing (and flavour-conserving) oscillations of Dirac-Majorana neutrinos both in vacuum and in matter. The general expressions for the transition probabilities in vacuum are reported. We then investigate some interesting consequences following from particular simple forms of the neutrino mass matrices, and for the envisaged scenarios we discuss in detail neutrino propagation in matter. Special emphasis is given to the problem of occurrence of resonant enhancement of active-active and active-sterile neutrino oscillations in a medium. The peculiar novel features related to the Dirac-Majorana nature of neutrinos are particularly pointed out.Comment: latex 2e, 19 pages, 1 figure; to be published in The European Journal of Physics

Reasons and opportunism control in public grants policies for development and innovations of businesses

In this paper we would to analyze the mechanism of public grants on economic growth. In particular this topic has been the subject of scientific interest by economists and, recently, also by business economics scholars. The studies of the economists focused on the motivations of the intervention itself; the business economic studies, on the other hand, have analyzed the impact both on the behavior of entrepreneurs and on the firms themselves by public grants. The studies examined so far highlight two basic conceptual dimensions, different, but also complementary to each other: on the one hand the economic-oriented to investigate the motivations and effectiveness of the public intervention; the second, business-oriented, focused on the firm’s behavior following public grant. Based on these arguments, our research question arises: could the effectiveness of public intervention for funding development and business innovation be influenced by the differences in the various socio-political and institutional contexts in which they are applied? The aim of paper is analyze the motivations of public grants policies and their influence on the behavior of firms. In this way we want to identify asolutions scheme able to recover efficiency and effectiveness of public actions to support development. It is therefore possible to identify some corrective mechanisms on public intervention policies. In particular with reference to the behaviors induced by the grants policies, the idea is to re-design the grants policies in consideration of the different forms of pre and post contractual opportunism. With reference, instead, to the motivations underlying the public grants policies, it is necessary to examine the relationship between the State (Principal) and the beneficiary firms (Agent) in relation to the respective dimensions of the contractual force

Essential self-adjointness in one-loop quantum cosmology

The quantization of closed cosmologies makes it necessary to study squared Dirac operators on closed intervals and the corresponding quantum amplitudes. This paper proves self-adjointness of these second-order elliptic operators.Comment: 14 pages, plain Tex. An Erratum has been added to the end, which corrects section

Positive or negative voting premium: what happened to private benefits in Italy?

A large body of research deals with voting premium as a proxy of private benefit of control. Almost all of them find positive voting premium, in particular in Italy. Therefore appears interesting to ask what is the current status of private benefits of control in Italy in the last decade (2007-2017). Surprisingly, we show three major findings: i) reduction of non-voting share in the Italian scenario; ii) prevalence of negative voting rights premium more than positive ones, thus conflicting with the assumption and the observations by other researchers; iii) limits of the voting premium method. Our aim is that this study, despite its limitations, may encourage further researches focused on the analysis of the improvement and the change in the Italian corporate governance. The article points out that interesting evidence already exists, although still much remains to do in the future

Three new X-ray emitting sdO stars discovered with Chandra

X-ray observations of sdO stars are a useful tool to investigate their properties, but so far only two sdO stars were detected at X-rays. We observed a complete flux-limited sample of 19 sdO stars with the Chandra HRC-I camera to measure the count rate of the detected sources or to set a tight upper limit on it for the undetected sources. We obtained a robust detection of BD+37 1977 and Feige 34 and a marginal detection of BD+28 4211. The estimated luminosity of BD+37 1977 is above 10^31 erg/s, which is high enough to suggest the possible presence of an accreting compact companion. This possibility is unlikely for all the other targets (both detected and undetected), since in their case L_X < 10^30 erg/s. On the other hand, for all 19 targets the estimated value of L_X (or its upper limit) implies an X-ray/bolometric flux ratio that agrees with log(L_X/L_bol) = -6.7 +/- 0.5, which is the range of values typical of main-sequence and giant O stars. Therefore, for Feige 34 and BD+28 4211 the observed X-ray flux is most probably due to intrinsic emission. The same is possibile for the 16 undetected stars.Comment: 6 pages. Accepted for publication by Astronomy and Astrophysic

Quantum Effects in Friedmann-Robertson-Walker Cosmologies

Electrodynamics for self-interacting scalar fields in spatially flat Friedmann-Robertson-Walker space-times is studied. The corresponding one-loop field equation for the expectation value of the complex scalar field in the conformal vacuum is derived. For exponentially expanding universes, the equations for the Bogoliubov coefficients describing the coupling of the scalar field to gravity are solved numerically. They yield a non-local correction to the Coleman-Weinberg effective potential which does not modify the pattern of minima found in static de Sitter space. Such a correction contains a dissipative term which, accounting for the decay of the classical configuration in scalar field quanta, may be relevant for the reheating stage. The physical meaning of the non-local term in the semiclassical field equation is investigated by evaluating this contribution for various background field configurations.Comment: 17 pages, plain TeX + 5 uuencoded figure

Biokinetics Of microbial consortia using biogenic sulfur as a novel electron donor for sustainable denitrification

In this study, the biokinetics of autotrophic denitrification with biogenic S0 (ADBIOS) for the treatment of nitrogen pollution in wastewaters were investigated. The used biogenic S0, a by-product of gas desulfurization, was an elemental microcrystalline orthorhombic sulfur with a median size of 4.69 µm and a specific surface area of 3.38 m2/g, which made S0 particularly reactive and bioavailable. During denitritation, the biomass enriched on nitrite (NO2–) was capable of degrading up to 240 mg/l NO2–-N with a denitritation activity of 339.5 mg NO2–-N/g VSS·d. The use of biogenic S0 induced a low NO2–-N accumulation, hindering the NO2–-N negative impact on the denitrifying consortia and resulting in a specific denitrification activity of 223.0 mg NO3–-N/g VSS·d. Besides Thiobacillus being the most abundant genus, Moheibacter and Thermomonas were predominantly selected for denitrification and denitritation, respectively

Force Percolation Transition of Jammed Granular Systems

The mechanical and transport properties of jammed materials originate from an underlying per- colating network of contact forces between the grains. Using extensive simulations we investigate the force-percolation transition of this network, where two particles are considered as linked if their interparticle force overcomes a threshold. We show that this transition belongs to the random percolation universality class, thus ruling out the existence of long-range correlations between the forces. Through a combined size and pressure scaling for the percolative quantities, we show that the continuous force percolation transition evolves into the discontinuous jamming transition in the zero pressure limit, as the size of the critical region scales with the pressure.Comment: 5 pages, 5 figure

Non-Local Boundary Conditions in Euclidean Quantum Gravity

Non-local boundary conditions for Euclidean quantum gravity are proposed, consisting of an integro-differential boundary operator acting on metric perturbations. In this case, the operator P on metric perturbations is of Laplace type, subject to non-local boundary conditions; by contrast, its adjoint is the sum of a Laplacian and of a singular Green operator, subject to local boundary conditions. Self-adjointness of the boundary-value problem is correctly formulated by looking at Dirichlet-type and Neumann-type realizations of the operator P, following recent results in the literature. The set of non-local boundary conditions for perturbative modes of the gravitational field is written in general form on the Euclidean four-ball. For a particular choice of the non-local boundary operator, explicit formulae for the boundary-value problem are obtained in terms of a finite number of unknown functions, but subject to some consistency conditions. Among the related issues, the problem arises of whether non-local symmetries exist in Euclidean quantum gravity.Comment: 23 pages, plain Tex. The revised version is much longer, and new original calculations are presented in section