The regular cosmic string in Born-Infeld gravity

It is shown that Born-Infeld gravity --a high energy deformation of Einstein gravity-- removes the singularities of a cosmic string. The respective vacuum solution results to be free of conical singularity and closed timelike curves. The space ends at a minimal circle where the curvature invariants vanish; but this circle cannot be reached in a finite proper time.Comment: 4 pages, submitted to Proceedings of Spanish Relativity Meeting 2010 (ERE2010, Granada, Spain

Stochastic resonance in a suspension of magnetic dipoles under shear flow

We show that a magnetic dipole in a shear flow under the action of an oscillating magnetic field displays stochastic resonance in the linear response regime. To this end, we compute the classical quantifiers of stochastic resonance, i.e. the signal to noise ratio, the escape time distribution, and the mean first passage time. We also discuss limitations and role of the linear response theory in its applications to the theory of stochastic resonance.Comment: 17 pages, 5 figures, approved for publication in PR

Enabling matter power spectrum emulation in beyond-ΛCDM cosmologies with COLA

We compare and validate COLA (COmoving Lagrangian Acceleration) simulationsagainst existing emulators in the literature, namely Bacco and Euclid Emulator2. Our analysis focuses on the non-linear response function, i.e., the ratiobetween the non-linear dark matter power spectrum in a given cosmology withrespect to a pre-defined reference cosmology, which is chosen to be the EuclidEmulator 2 reference cosmology in this paper. We vary three cosmologicalparameters, the total matter density, the amplitude of the primordial scalarperturbations and the spectral index. By comparing the COLA non-linear responsefunction with those computed from each emulator in the redshift range $0 \leq z\leq 3$, we find that the COLA method is in excellent agreement with the twoemulators for scales up to $k \sim 1 \ h$/Mpc as long as the deviations of thematter power spectrum from the reference cosmology are not too large. Wevalidate the implementation of massive neutrinos in our COLA simulations byvarying the sum of neutrino masses to three different values, $0.0$ eV, $0.058$eV and $0.15$ eV. We show that all three non-linear prescriptions used in thiswork agree at the $1\%$ level at $k \leq 1 \ h$/Mpc. We then introduce theEffective Field Theory of Dark Energy in our COLA simulations using the$N$-body gauge method. We consider two different modified gravity models inwhich the growth of structure is enhanced or suppressed at small scales, andshow that the response function with respect to the change of modified gravityparameters depends weakly on cosmological parameters in these models.<br

Leptogenesis with Almost Degenerate Majorana Neutrinos

We investigate the leptogenesis with almost degenerate neutrinos, in the framework of democratic mass matrix, which naturally explains the large mixing angles for neutrino oscillations as well as quark masses and mixing matrix. We find that the baryon asymmetry in the present universe is explained via the decays of right-handed neutrinos produced nonthermally by the inflaton decay. The model predicts neutrinoless double beta decays accessible in near future experiments.Comment: 17 pages, LaTeX, 2 figure

Solubility, Light Output and Energy Resolution Studies of Molybdenum-Loaded Liquid Scintillators

The search for neutrinoless double-beta decay is an important part of the global neutrino physics program. One double-beta decay isotope currently under investigation is 100Mo. In this article, we discuss the results of a feasibility study investigating the use of molybdenum-loaded liquid scintillator. A large, molybdenum-loaded liquid scintillator detector is one potential design for a low-background, internal-source neutrinoless double-beta decay search with 100Mo. The program outlined in this article included the selection of a solute containing molybdenum, a scintillating solvent and the evaluation of the mixture's performance as a radiation detector.Comment: 8 pages, 3 figure

Night vision imaging systems design, integration, and verification in military fighter aircraft

This paper describes the developmental and testing activities conducted by the Italian Air Force Official Test Centre (RSV) in collaboration with Alenia Aerospace, Litton Precision Products and Cranfiled University, in order to confer the Night Vision Imaging Systems (NVIS) capability to the Italian TORNADO IDS (Interdiction and Strike) and ECR (Electronic Combat and Reconnaissance) aircraft. The activities consisted of various Design, Development, Test and Evaluation (DDT&amp;E) activities, including Night Vision Goggles (NVG) integration, cockpit instruments and external lighting modifications, as well as various ground test sessions and a total of eighteen flight test sorties. RSV and Litton Precision Products were responsible of coordinating and conducting the installation activities of the internal and external lights. Particularly, an iterative process was established, allowing an in-site rapid correction of the major deficiencies encountered during the ground and flight test sessions. (cont.

Position-based simulation of deformations for autonomous robotic ultrasound scanning

Realistic and fast simulation of anatomical deformations due to ultrasound probe pressure is of outstanding importance for testing and validation of autonomous robotic ultrasound systems. We propose a deformation model which relies on the position-based dynamics (PBD) approach to simulate the probetissue interaction and predict the displacement of internal targets during US acquisition. Performances of the patient-specific PBD anatomical model are evaluated in comparison to two different simulations relying on the traditional finite element (FE) method, in the context of breast ultrasound scanning. Localization error obtained when applying the PBD model remains below 11 mm for all the tumors even for input displacements in the order of 30 mm. The proposed method is able to achieve a better trade-off among accuracy, computation time and generalization capabilities with respect to the two FE models. Position-based dynamics approach has proved to be successful in modeling breast tissue deformations during US acquisition. It represents a valid alternative to classical FE methods for simulating the interaction between US probe and tissues

Damping signatures in future neutrino oscillation experiments

We discuss the phenomenology of damping signatures in the neutrino oscillation probabilities, where either the oscillating terms or the probabilities can be damped. This approach is a possibility for tests of non-oscillation effects in future neutrino oscillation experiments, where we mainly focus on reactor and long-baseline experiments. We extensively motivate different damping signatures due to small corrections by neutrino decoherence, neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and classify these signatures according to their energy (spectral) dependencies. We demonstrate, at the example of short baseline reactor experiments, that damping can severely alter the interpretation of results, e.g., it could fake a value of $\sin(2\theta_{13})$ smaller than the one provided by Nature. In addition, we demonstrate how a neutrino factory could constrain different damping models with emphasis on how these different models could be distinguished, i.e., how easily the actual non-oscillation effects could be identified. We find that the damping models cluster in different categories, which can be much better distinguished from each other than models within the same cluster.Comment: 33 pages, 5 figures, LaTeX. Final version published in JHE

MNS Parameters from Neutrino Oscillations, Single Beta Decay and Double Beta Decay

We examine the constraints on the MNS lepton mixing matrix =66rom the present and future experimental data of the neutrino oscillation, tritium beta decay, and neutrinoless double beta decay for Majorana neutrinos. We show that the small mixing angle solutions for solar neutrino problem are disfavored for small averaged mass () of neutrinoless double beta decay ($\leq 0.01$ eV) in the inverse neutrino mass hierarchy scenario. This is the case even in the normal mass hierarchy scenario except for very restrictive value of the averaged neutrino mass ($\bar{m_\nu}$) of single beta decay. The lower mass bound for $\bar{m_\nu}$ is given from the present neutrino oscillation data. We obtain some relations between and $\bar{m_\nu}$. The constraints on the Majorana CP violating phases are also given.Comment: 25pages, 10figure