Ubiquitous Internet in an integrated satellite-terrestrial environment: The SUITED solution

yesThe current Internet architecture appears to not be particularly suited to addressing the emerging needs of new classes of users who wish to gain access to multimedia services made available by ISPs, regardless of their location, while in motion and with a guaranteed level of quality. One of the main objectives of so-called nextgeneration systems is to overcome the limitations of today¿s available Internet by adopting an approach based on the integration of different mobile and fixed networks. The SUITED project moves in this direction since it aims at contributing to the design and deployment of the global mobile broadband system (GMBS), a unique satellite/terrestrial infrastructure ensuring nomadic users access to Internet services with a negotiated QoS. A description of the main features of the GMBS architecture, characterized by the integration of a multisegment access network with a federated ISP network is given in this article. The GMBS multimode terminal is schematically described, and an overview of the so-called QoS-aware mobility management scheme, devised for such a heterogeneous scenario,is provided

Pfaffian representations of cubic surfaces

Let K be a field of characteristic zero. We describe an algorithm which requires a homogeneous polynomial F of degree three in K[x_0,x_1,x_2,x_3] and a zero A of F in P^3_K and ensures a linear pfaffian representation of V(F) with entries in K[x_0,x_1,x_2,x_3], under mild assumptions on F and A. We use this result to give an explicit construction of (and to prove the existence of) a linear pfaffian representation of V(F), with entries in K'[x_0,x_1,x_2,x_3], being K' an algebraic extension of K of degree at most six. An explicit example of such a construction is given.Comment: 17 pages. Expanded with some remarks. Published with minor corrections in Geom. Dedicat

Travelling waves in a mixture of gases with bimolecular reversible reactions

Starting from the kinetic approach for a mixture of reacting gases whose particles interact through elastic scattering and a bimolecular reversible chemical reaction, the equations that govern the dynamics of the system are obtained by means of the relevant Boltzmann-like equation. Conservation laws are considered. Fluid dynamic approximations are used at the Euler level to obtain a close set of PDEs for six unknown macroscopic fields. The dispersion relation of the mixture of reacting gases is explicitly derived in the homogeneous equilibrium state. A set of ODE that governs the propagation of a plane travelling wave is obtained using the Galilei invariance. After numerical integration some solutions, including the well-known Maxwellian and the hard spheres cases, are found for various meaningful interaction laws. The main macroscopic observables for the gas mixture such as the drift velocity, temperature, total density, pressure and its chemical composition are shown.Comment: 13 pages, 2 figures, accepted on Physica

Is the solar neutrino deficit energy-dependent?

All existing measurements of the solar neutrino flux are compared with the predictions of the most recent solar model by Bahcall and Pinsonneault, modified by introducing the hypothesis of neutrino oscillations with mass differences large enough to render energy-independent any quantity observable on earth. It is concluded that the data are consistent with this hypothesis and that, at least for the time being, any energy-dependence of the solar neutrino deficit must be regarded as just an attractive theoretical possibility, but not as a compelling reality.Comment: 6 pages, 1 figure, contributed paper to the XVIII Int. Symposium on Lepton-Photon Interactions, Hamburgh, Germany, 28 July - 1 August 199

Rates for the reactions antiproton-proton --> pi phi and gamma phi

We study antiproton-proton annihilation at rest into $\pi\phi$ and $\gamma\phi$. Rescattering by $\overline{K^*}K+K^*\overline{K}$ and $\rho^{+}\rho^{-}$ for $\overline{p}p\rightarrow\pi\phi$ states is sizable, of order $(0.90\, {\rm to}\,2.6)\times 10^{-4}$ in the branching ratio, but smaller than experiment. For $\overline{p}p\rightarrow\gamma\phi$ the rescattering contributions are negligible, but the $\gamma\phi$ channel is well explained by a $\rho\phi$ intermediate state combined with vector meson dominance.Comment: 12 pages, plain latex, 2 postscript figures available upon request, PSI-PR-93-2

MEASURING REGULARITY OF FINE UPPER LIMB MOVEMENTS WITH A HAPTIC PLATFORM FOR MOTOR LEARNING AND REHABILITATION

Robot-assisted systems for arm training are being increasingly used to target moderate-to-severe upper limb impairments in rehabilitation facilities, while hand fine motor skills are seldom being targeted by these machines. This manuscript describes and tests the feasibility of a system based on a haptic interface aimed to complement the efficacy of robotic training in the rehabilitation and motor learning associated with upper extremities movements. End-effector kinematics associated with different trajectory tasks performed by 11 healthy adults were used to extract measures of smoothness, under different testing conditions that included the presence or absence of visual and haptic feedback, the use of dominant vs. non dominant hand, different shapes (crosses and circles), and the verse with which movements were done. The normalized mean square jerk, extracted from the system together with specific speed parameters, was able to capture differences in regularity between the different shapes (MSJratio significantly higher when drawing crosses, p < 1.0 E-4), and that haptic feedback significantly influences this smoothness measure (MSJratio significantly higher when haptic feedback is present, p < 5.0 E-4). The proposed system may be used as a means to monitor the progress of movement regularity in robot-mediated therapy, and the results obtained experimentally highlight the influence of haptic feedback on the smoothness of finalized upper extremity fine movements