Fiber-top cantilevers: a new sensor on the tip of a fiber

Micromachined cantilevers are the most elementary example of miniaturized sensors. A free-standing rectangular beam can often detect changes in the chemical, biological and physical properties of the surroundings with sensitivity comparable to much more complicated devices. It is therefore not surprising that this simple design is still at the heart of several scientific instruments

Improvement of the Energy Recovery of Traction Electrical Drives using Supercapacitors

In the paper the possibility of improving the energy recovered during the braking of railway vehicles and reduction of power peaks during accelerating are discussed. The energy available from the regenerative braking of the motor is stored into supercapacitor sets placed on board and reused subsequently for the acceleration of the train. This auxiliary storage system allows the reduction of the losses on the line, because the power peaks are shaved by supercapacitors and, hence, the rms power supplied is reduced. In addition, also the energy consumption of the train can be reduced respect to traditional convoys, especially if the characteristic duty cycle presents many accelerations and braking periods as the case of subways trains. The set of supercapacitors needs the use of an intermediate dc/dc converter in order to harmonize the voltage with that of the dc-link of the drive and control the power flows of the supercapacitors. The mathematical model of the whole system and the control strategy of energy management are presented. The actual possibilities of the energy recovery are shown by means of numeric simulations and expressed in percentage respect to the energy drawn during accelerations. The control strategy has been experimentally validated on a scale system made of an asynchronous drive supplied by a dc source and a set of supercapacitors as auxiliary storage device

Investigation of the concept of beauty via a lock-in feedback experiment

Lock-in feedback circuits are routinely used in physics laboratories all around the world to extract small signals out of a noisy environment. In a recent paper (M. Kaptein, R. van Emden, and D. Iannuzzi, paper under review), we have shown that one can adapt the algorithm exploited in those circuits to gain insight in behavioral economics. In this paper, we extend this concept to a very subjective socio-philosophical concept: the concept of beauty. We run an experiment on 7414 volunteers, asking them to express their opinion on the physical features of an avatar. Each participant was prompted with an image whose features were adjusted sequentially via a lock-in feedback algorithm driven by the opinion expressed by the previous participants. Our results show that the method allows one to identify the most attractive features of the avatar

Halving the Casimir force with conductive oxides

The possibility to modify the strength of the Casimir effect by tailoring the dielectric functions of the interacting surfaces is regarded as a unique opportunity in the development of Micro- and NanoElectroMechanical Systems. In air, however, one expects that, unless noble metals are used, the electrostatic force arising from trapped charges overcomes the Casimir attraction, leaving no room for exploitation of Casimir force engineering at ambient conditions. Here we show that, in the presence of a conductive oxide, the Casimir force can be the dominant interaction even in air, and that the use of conductive oxides allows one to reduce the Casimir force up to a factor of 2 when compared to noble metals.Comment: modified version, accepted for publication in Phys Rev Let

Progress towards Bell-type polarization experiment with thermal neutrons

Experimental tests of Bell-type inequalities distinguishing between quantum mechanics and local realistic theories remain of considerable interest if performed on massive particles, for which no conclusive result has yet been obtained. Only two-particle experiments may specifically test the concept of spatial nonlocality in quantum theory, whereas single-particle experiments may generally test the concept of quantum noncontextuality. Here we have performed the first Bell-type experiment with a beam of thermal-neutron pairs in the singlet state of spin, as originally suggested by J. S. Bell. These measurements confirm the quantum-theoretical predictions, in agreement with the results of the well-known polarization experiments carried out on optical photons years ago

Characterizing tissue stiffness at the tip of a rigid needle using an opto-mechanical force sensor

We present a novel device that allows the user to measure the Young Modulus of a material at the opening of a 5 mm diameter needle. The device relies on a miniaturized cantilever spring mounted at the end of the needle and interrogated via Fabry-Perot optical fiber interferometry. The probe is repetitively brought in and out of contact with the sample at the end of the needle by means of a steel cable that is controlled via a piezoelectric actuator located at the proximal end. We demonstrate the ability of our device to detect and quantify layers of varying stiffness during needle insertion in a gelatin phantom and to successfully locate tissue boundaries in bovine liver tissue embedded in gelatin

No anomalous scaling in electrostatic calibrations for Casimir force measurements

In a recent paper (Phys.Rev.A78, 020101(R) (2008)), Kim at al. have reported a large anomaly in the scaling law of the electrostatic interaction between a sphere and a plate, which was observed during the calibration of their Casimir force set-up. Here we experimentally demonstrate that in proper electrostatic calibrations the scaling law follows the behavior expected from elementary electrostatic arguments, even when the electrostatic voltage that one must apply to minimize the force (typically ascribed to contact potentials) depends on the separation between the surfaces.Comment: Final versio

Detailed description of RBA-banded chromosomes of river buffalo (Bubalus bubalis L.)

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