Complex scalar field in κ\kappa-Minkowski spacetime

It is often expected that one cannot treat spacetime as a continuous manifold as the Planck scale is approached, because of to possible effects due to a quantum theory of gravity. There have been several proposals to model such a deviation from the classical behaviour, one of which is noncommutativity of spacetime coordinates. In this context, the non-commutativity scale is seen as an observer-independent length scale. Of course, such a scale impose a modification of ordinary relativistic symmetries, which now need to be deformed to accommodate this fundamental scale. The $\kappa$-Poincar\'e algebra is an example of this deformation. In what follows I will briefly describe a construction of a $\kappa$-deformed complex scalar field theory, while at the same time shedding light on the behaviour of discrete and continuous symmetries in this formalism. This in turn will open the way to the study of the application of this formalism to actual physical processes. I will then conclude with some comments and prospects for the future.Comment: Presented at the 8th Conference of the Polish Society on Relativit

Global Solutions for Two-Phase Complex Fluids with Quadratic Anchoring in Soft Matter Physics

We study a diffuse interface model describing the complex rheology and the interfacial dynamics during phase separation in a polar liquid-crystalline emulsion. More precisely, the physical systems comprises a two-phase mixture consisting in a polar liquid crystal immersed in a Newtonian fluid. Such composite material is a paradigmatic example of complex fluids arising in Soft Matter which exhibits multiscale interplay. Beyond the Ginzburg-Landau and Frank elastic energies for the concentration and the polarization, the free energy of the system is characterized by a quadratic anchoring term which tunes the orientation of the polarization at the interface. This leads to several quasi-linear nonlinear couplings in the resulting system describing the macroscopic dynamics. In this work, we establish the first mathematical results concerning the global dynamics of two-phase complex fluids with interfacial anchoring mechanism. First, we determine a set of sufficient conditions on the parameters of the system and the initial conditions which guarantee the existence of global weak solutions in two and three dimensions. Secondly, we show that weak solutions are unique and globally regular in the two dimensional case. Finally, we complement our analysis with some numerical simulations to display polarization and interfacial anchoring.Comment: 52 pages, 5 figure

A 64-Channel 965-μW Neural Recording SoC with UWB Wireless Transmission in 130-nm CMOS

This brief presents a 64-channel neural recording system-on-chip (SoC) with a 20-Mb/s wireless telemetry. Each channel of the analog front end consists of a low-noise bandpass amplifier, featuring a noise efficiency factor of 3.11 with an input-referred noise of 5.6 μVrms in a 0.001- to 10-kHz band and a 31.25-kSps 6-fJ/conversion-step 10-bit SAR analog-to-digital converter. The recorded signals are multiplexed in the digital domain and transmitted via an 11.7% efficiency pulse-position modulation ultrawideband transmitter, reaching a transmission range in excess of 7.5 m. The chip has been fabricated in a 130-nm CMOS process, measures 25 mm2, and dissipates 965 μW from a 0.5-V supply. This SoC features the lowest power per channel (15 μW) and the lowest energy per bit (48.2 pJ) among state-of-the-art wireless neural recording systems with a number of channels larger than 32. The proposed circuit is able to transmit the raw neural signal in a large bandwidth (up to 10 kHz) without performing any data compression or losing vital information, such as local field potentials

Propagazione di single-event transients in logiche combinatorie

Lo scopo di questa trattazione è quello di studiare la propagazione dei SET (Single-Event Transients) in catene di inverter implementate a partire da porte logiche di tipo NOT NOR e NAND, tramite l’ausilio di un simulatore tridimensionale. Lo studio è stato condotto in modo tale da poter valutare il comportamento di tali catene in funzione del bilanciamento delle porte logiche stesse, al variare del LET delle particelle ionizzanti.ope

La misura di occupazione del moto browniano: tempi locali rispetto a varieta' e disintegrazione rispetto a foliazioni differenziabili.

Tempi locali: definizione e proprietà. Teoremi di Le Gall sull’unicità forte nelle equazioni differenziali stocastiche, che usano i tempi locali. Proprietà della misura di occupazione del moto browniano in dimensione >1, costruzione dei tempi locali di un moto browniano N dimensionale rispetto alle intersezioni con varieta’ N-1 dimensionali. Una nuova formula di rappresentazione della misura di occupazione in dimensione qualsiasi, che la disintegra rispetto ad una foliazione differenziabile. In essa si ottiene il tempo locale rispetto alle foglie e un nucleo di misure concentrate sulle foglie. Proprieta’ e possibili usi di questa disintegrazione per integrare funzioni poco regolari rispetto alla misura di occupazione

The effects of vent location, event scale and time forecasts on pyroclastic density current hazard maps at Campi Flegrei caldera (Italy)

This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC) originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modeled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr.Mean and percentilemaps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538) marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of 25% in the central part of the caldera). In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e., including both eruptive epochs and quiescent periods