A. Nicolaidis

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We describe an experimental arrangement for comparison of user performance during a real and a virtual 3-D peg-in-hole task. Tasks are performed using a unique six-degree-of-freedom (6-DOF) magnetic levitation haptic device. The arrangement allows a user to exert and experience real and virtual forces using the same 6-DOF device. During the virtual task, a(More)
We describe two experiments using three testbeds (real, virtual and vision-only) for comparison of user performance during 3-D peg-in-hole tasks. Tasks are performed using a six-degree-of-freedom (6-DOF) magnetic levitation haptic device. The experimental design allows a user to experience real and virtual forces using the same device. The first experiment(More)
The modelling of the human thorax and the impedance characteristics of the thorax are presented. A two-dimensional model of the thorax was constructed by using more than four hundred reference points. The input impedance was calculated by solving the Helmholtz equation for zero charge density and low frequencies. Variation in the impedance corresponds to(More)
We have proposed that the cosmic ray spectrum “knee”, the steepening of the cosmic ray spectrum at energy E > ∼ 1015.5 eV, is due to “new physics”, namely new interactions at TeV cm energies which produce particles undetected by the experimental apparatus. In this letter we examine specifically the possibility that this interaction is low scale gravity. We(More)
The phenomenon of string spreading on the black hole horizon, as originally discussed by Susskind, is considered in the exact curved Schwarzschild background. We consider an oscillating string encircling the black hole and contracting towards the horizon. We then compute the angular and radial spreading of the string, as seen by a static observer at spatial(More)
The dispersion relation of energetic (few TeV) neutrinos traversing a medium is studied. We use the real time formalism of thermal field theory and we include the effects from the propagator of the W gauge boson. We consider then the MSW oscillations for cosmic neutrinos traversing the Earth, adopting for the neutrino parameters values suggested by the LSND(More)
Theories with large extra dimensions provide the possibility that a flavor neutrino, localized in a 3+1 brane, can mix with a singlet neutrino living in the bulk. This mixing leads to unconventional patterns of neutrino matter oscillations and we examine in details how these oscillations depend upon two parameters: the brane-bulk coupling ξ and the(More)