Compared EC-AFM Analysis of Laser-Induced Graphene and Graphite Electrodes in Sulfuric Acid Electrolyte

Flexible and economic sensor devices are the focus of increasing interest for their potential and wide applications in medicine, food analysis, pollution, water quality, etc. In these areas, the possibility of using stable, reproducible, and pocket devices can simplify the acquisition of data. Among recent prototypes, sensors based on laser-induced graphene (LIGE) on Kapton represent a feasible choice. In particular, LIGE devices are also exploited as electrodes for sensing in liquids. Despite a characterization with electrochemical (EC) methods in the literature, a closer comparison with traditional graphite electrodes is still missing. In this study, we combine atomic force microscopy with an EC cell (EC-AFM) to study, in situ, electrode oxidation reactions when LIGE or other graphite samples are used as anodes inside an acid electrolyte. This investigation shows the quality and performance of the LIGE electrode with respect to other samples. Finally, an ex situ Raman spectroscopy analysis allows a detailed chemical analysis of the employed electrodes.     

Optical signal-to-noise ratio measurement by optical homodyne tomography

An all-fiber optical homodyne tomography setup is introduced that measures the optical signal-to-noise ratio through reconstruction of the photon statistics. The scheme described has been conceived for applications to optical communications. In particular, the signal-to-noise ratio has been evaluated at lambda= 1.55 microm as a function of the received power. From the experimental data, in the case of optically amplified signals, the amplifier noise figure can be estimated.     

Mixing Length Scales of Low Temperature Spin Plaquettes Models

Plaquette models are short range ferromagnetic spin models that play a key role in the dynamic facilitation approach to the liquid glass transition. In this paper we perform a rigorous study of the thermodynamic properties of two dimensional plaquette models, the square and triangular plaquette models. We prove that for any positive temperature both models have a unique infinite volume Gibbs measure with exponentially decaying correlations. We analyse the scaling of three a priori different static correlation lengths in the small temperature regime, the mixing, cavity and multispin correlation lengths. Finally, using the symmetries of the model we determine an exact self similarity property for the infinite volume Gibbs measure.     

Time Scale Separation and Dynamic Heterogeneity in the Low Temperature East Model

We consider the non-equilibrium dynamics of the East model, a linear chain of 0–1 spins evolving under a simple Glauber dynamics in the presence of a kinetic constraint which forbids flips of those spins whose left neighbor is 1. We focus on the glassy effects caused by the kinetic constraint as ${q\downarrow 0}$ , where q is the equilibrium density of the 0s. In the physical literature this limit is equivalent to the zero temperature limit. We first prove that, for any given L = O(1/q), the divergence as ${q\downarrow 0}$ of three basic characteristic time scales of the East process of length L is the same. Then we examine the problem of dynamic heterogeneity, i.e., non-trivial spatio-temporal fluctuations of the local relaxation to equilibrium, one of the central aspects of glassy dynamics. For any mesoscopic length scale L = O(q ^?γ ), γ < 1, we show that the characteristic time scale of two East processes of length L and λ L respectively are indeed separated by a factor q ^?α , α = α(γ) > 0, provided that λ ≥ 2 is large enough (independent of q, λ = 2 for γ < 1/2). In particular, the evolution of mesoscopic domains, i.e., maximal blocks of the form 111..10, occurs on a time scale which depends sharply on the size of the domain, a clear signature of dynamic heterogeneity. A key result for this part is a very precise computation of the relaxation time of the chain as a function of (q, L), well beyond the current knowledge, which uses induction on length scales on one hand and a novel algorithmic lower bound on the other. Finally we show that no form of time scale separation occurs for γ = 1, i.e., at the equilibrium scale L = 1/q, contrary to what was assumed in the physical literature based on numerical simulations.     

Controlled dumping of pulses of laser radiation ranging from MIR to the MM by means of optical semiconductor switching

A simple method to produce sub-ns pulses of laser radiation with wavelength ranging from middle infrared (MIR) to millimeter (MM) is experimentally demonstrated. The system operates with a single OSS (optical semiconductor switching) driven by a ns Nd laser. Pulse control is produced by varying the distance of a mirror from an OSS used as a cavity dumping. The effectiveness of this sub-ns MM pulse generation is larger than the one observed in other schemes. Pulses with 500-ps FWHM and 15-W power were produced at 2.65 mm with a time compression compared to the 2-ns FWHM of the 1.06-μm driving laser. Received: 30 October 2000 / Revised version: 26 January 2001 / Published online: 9 May 2001     

Contributi alla teoria dei residui per le funzioni di due variabili complesse

Sunto Si assegna una condizione necessaria e sufficiente per la validità di una formula diCaccioppoli generalizzazione2-dimensionale dell'indicatore logaritmico. A Mauro Picone nel suo 70^mo compleanno.     

Electroproduction of supersymmetric particles and gauge bosons

The electroproduction of scalar leptons and gauginos at HERA and at supercollider energies is studied. In particular, the channel $\text{ep}\text{→}\text{e}\text{(→}\text{e}\text{+}\text{γ}\text{)}\text{γ}\text{X}$ is analyzed in full detail. The exa analytic expressions for the cross section and the spectrum of the final electron are derived and evaluated for $\text{√s ? 0.15?3}\text{TeV}$ and different values of the scalar electron and photino masses. Since the exact formulae are relatively complicated, simplified expressions in the Weizsäcker-Williams approximation are also given and their accuracy is discussed by comparison with the exact formulae. The standard processes $\text{ep}\text{→}\text{Z}\text{(→ v}\text{v}\text{)}\text{eX and ep}\text{→}\text{W}\text{(→}\text{e}\text{v}\text{)v}\text{X}$ which also lead to one final electron and two invisible particles are considered in parallel. The corresponding cross sections and distributions are discussed in comparison with the supersymmetric signal. The Z⁰ cross section is found to be quite smaller than was reported previously. To clarify this point the Z⁰ production at the leptonic vertex was computed both exactly and in the Weizsäcker-Williams approximation with quite consistent results.     

The transverse hadronic energy inW andZ 0 production

A thorough analysis is presented of the hadronic transverse energy produced in association withW ^± andZ ⁰ weak bosons atp \(\bar p\) colliders. The complete rapidity and transverse energy distributions are derived, including the perturbative annihilation and Compton terms and the resummation of soft gluons. The first non leading corrections to the corresponding Sudakov exponent are included in full and their effects are discussed. To make contact with the actual data a number of non perturbative inputs is also necessary. We extract this information from minimum bias measurements. A detailed comparison of the resulting theoretical predictions with the available experimental data is finally presented.