New limits from the Milano neutrino mass experiment with thermal microcalorimeters

In the Standard Model of electroweak interactions an important input parameter is still missing: the absolute value of the mass of one of the neutrinos. In this paper we report the final results of the Milano electron anti-neutrino mass experiment after having measured for about one year the beta spectrum of ¹⁸⁷Re with 10 AgReO₄ microcalorimeters. We describe the experimental set-up, the detector performance and the measuring conditions. We present the updated limit on the electron anti-neutrino mass which is the most stringent so far obtained with thermal detectors. We also give the most precise estimates for the ¹⁸⁷Re transition energy and lifetime.     

Switching control approach for stable navigation of mobile robots in unknown environments

This paper presents a stable switching control strategy for the parking problem of non-holonomic mobile robots. First, it is proposed a positioning-orientation switching controller for the parking problem. With this strategy robot backwards motions are avoided and the robot heading is always in the direction of the goal point facilitating the obstacle handling. Second, the avoidance of unexpected obstacles is considered in a reactive way by following the contour of the obstacles. Next, the stability of the switching parking/obstacle-avoider controller is analyzed showing stability under reasonable conditions. Finally, the good performance and the feasibility of this approach are shown through several experimental results.     

Physical motivations for thermal detectors

The resistivity of two-dimensional electrons on the surface of liquid helium can be measured using the Sommer-Tanner technique in which a rectangular array of electrodes is placed beneath the liquid surface. An ac voltage is applied to one electrode and the phase of the signal at another electrode is measured. In zero magnetic field the phase shift ₀ from that of purely capacitative coupling is proportional to the resistivity ₀ of the electron sheet. A simple expression is given for the phase shift in a magnetic field (B), which depends on both _xx and _xy , the components of the magnetoresistivity tensor, and on the aspect ratio of the electrodes. Experimental results are presented and analysed using this expression.     

Activation of solid polymer surfaces with bifunctional reagents

An original procedure is described which calls upon the heterogeneous grafting of bifunctional molecules onto a reactive polymeric surface, leaving one of the functions available for further exploitation. The principle of this strategy is to use reagents characterised by a rigid planar structure bearing the two active moieties at opposite sites of the molecule. The examples provided include the reactions of lignocellulosic fibres with 1,4‐phenyl diisocyanate and 1,2,4,5‐benzenetetracarboxylic anhydride, which give rise to their surface activation through the incorporation of covalently bound isocyanate or anhydride functions. © 2001 Society of Chemical Industry     

Inductive learning of answer set programs for autonomous surgical task planning

Machine Learning - The quality of robot-assisted surgery can be improved and the use of hospital resources can be optimized by enhancing autonomy and reliability in the robot’s operation....