Forensic metrology: its importance and evolution

Measurements play a fundamental role in nowadays forensic activities, especially in criminal justice. Guilt or innocence and the severity of a sentence do often depend upon the results of measurements. On the other hand, it is well-known that measurement results are always affected by uncertainty, so that any decision based on measurement results carries an implicit risk of being wrong: uncertainty helps in estimating this risk. If this concept is translated into the juridical world, it is quite immediate to recognize that uncertainty may quantify how reasonable is the doubt with which a verdict is rendered by the trier of facts. Unfortunately, forensic disciplines are still largely unaware of the basic, fundamental concepts of metrology. This paper is aimed at showing how forensic metrology is developing in different countries and reporting a few cases where metrology played a key role

Optical Phase Locking techniques: an overview and a novel method based on Single Side Sub-Carrier modulation

A short overview on Optical Phase locking techniques and a detailed description of the Phase Locking technique based on Sub-Carriers modulation is presented. Furthermore, a novel Single Side Sub-Carrierbased Optical Phase Locked Loop (SS-SC-OPLL), with off the shelf optical components, is also presented and experimentally demonstrated. Our new method, based on continuous wave semiconductor lasers and optical single side sub-carrier modulation using QPSK LiNbO3 modulator, allows a practical implementation with better performance with respect to the previously proposed OPLL circuits, and permits an easy use in real time WDM signal coherent demodulation

Homodyne coherent detection of ASK and PSK signals performed by a subcarrier optical phase-locked loop

Optical transmission systems based on homodyne coherent detection of 2-ASK and pilot carrier 2-PSK signals have been implemented. ASK data has been transmitted at 2.5 Gbps, while 2.5 Gbps and 10 Gbps PSK systems have been tested. The proposed architecture is based on a new optical phase locked loop founded on sub-carrier modulation and leads to new compact integrated receivers and new transmission formats, thus opening new opportunities for future optical systems

On semilinear elliptic equations with borderline Hardy potentials

In this paper we study the asymptotic behavior of solutions to an elliptic equation near the singularity of an inverse square potential with a coefficient related to the best constant for the Hardy inequality. Due to the presence of a borderline Hardy potential, a proper variational setting has to be introduced in order to provide a weak formulation of the equation. An Almgren-type monotonicity formula is used to determine the exact asymptotic behavior of solutions