Alcatel-Lucent

About: Alcatel-Lucent is a based out in Stuttgart, Germany. It is known for research contribution in the topics: Signal & Network packet. The organization has 37003 authors who have published 53332 publications receiving 1430547 citations. The organization is also known as: Alcatel-Lucent S.A. & Alcatel.

Theory of the Two‐ and One‐Dimensional Rigid Sphere Fluids

Abstract: The approximate theory of the three‐dimensional hard sphere fluid developed by Reiss, Frisch, and Lebowitz has given astonishingly good predictions with little labor. In an attempt to investigate the reason for this result we adduce, in this paper, further evidence for the internal consistency of the approximations of this theory. Thus it is noted that the same equation of state of hard sphere fluid is obtained when one used the ``integral condition'' as when the ``infinity condition'' is used. We have then applied the theory to study the thermodynamic properties, in particular the equation of state, of the rigid sphere fluid in two and one dimensions. The approximate equation of state of the two‐dimensional rigid sphere fluid is in good agreement over the range of fluid densities with the results of the machine Monte Carlo calculations by Jacobson and Wood and dynamical machine calculations of Wainwright and Alder. The exact Tonks' equation of state of the one‐dimensional rigid sphere fluid is derived in a particularly simple manner.

Equilibrium properties of temporally asymmetric Hebbian plasticity.

Abstract: A theory of temporally asymmetric Hebb rules, which depress or potentiate synapses depending upon whether the postsynaptic cell fires before or after the presynaptic one, is presented. Using the Fokker-Planck formalism, we show that the equilibrium synaptic distribution induced by such rules is highly sensitive to the manner in which bounds on the allowed range of synaptic values are imposed. In a biologically plausible multiplicative model, the synapses in asynchronous networks reach a distribution that is invariant to the firing rates of either the presynaptic or postsynaptic cells. When these cells are temporally correlated, the synaptic strength varies smoothly with the degree and phase of their synchrony.

On the mechanism of the hydrogen-induced exfoliation of silicon

Abstract: We have investigated the fundamental mechanism underlying the hydrogen-induced exfoliation of silicon, using a combination of spectroscopic and microscopic techniques. We have studied the evolution of the internal defect structure as a function of implanted hydrogen concentration and annealing temperature and found that the mechanism consists of a number of essential components in which hydrogen plays a key role. Specifically, we show that the chemical action of hydrogen leads to the formation of (100) and (111) internal surfaces above 400 °C via agglomeration of the initial defect structure. In addition, molecular hydrogen is evolved between 200 and 400 °C and subsequently traps in the microvoids bounded by the internal surfaces, resulting in the build-up of internal pressure. This, in turn, leads to the observed “blistering” of unconstrained silicon samples, or complete layer transfer for silicon wafers joined to a supporting (handle) wafer which acts as a mechanical “stiffener.”

Wireless multi-media messaging communications method and apparatus

Abstract: A wireless multimedia messaging communications method and apparatus that permits a subscriber to a wireless telecommunications service to receive and generate multimedia messages from known wireless personal communications devices, i.e., cellular/PCS telephones. A multimedia message may be received by the network and selectively delivered to a subscriber of the wireless service. Upon receipt of the message, the network determines an appropriate action to take with respect to the message based upon a profile of the subscriber. The subscriber is then notified by the network of the message and then delivers the message and any multimedia attachments to the message to the subscriber, according to a delivery indication sent by the subscriber to the network. Advantageously, the method allows for the conversion of messages as appropriate, i.e., text-to-speech, text-to-fax, provides gateways to varieties of multimedia information such as that found on the Internet and provides an active messaging format wherein message templates are stored on a mobile device that interprets the active messages thereby permitting a subscriber to quickly compose a message by supplying simple, dynamic components of the message.

Controlling the sign of quantum interference by tunnelling from quantum wells

Abstract: The sign of the interference (constructive or destructive) between quantum-mechanical paths depends on the phase difference between the paths. In the Fano effect1 two optical paths from the ground state of a system — one direct and one mediated by a resonance — to a state in an energy continuum interfere to produce an asymmetric absorption spectrum that falls to zero near the absorption maximum. Zero absorption occurs as the wavelength is scanned across the resonance, at a photon energy corresponding to a 180 ° phase difference between the paths. Similar interference effects occur when two absorption paths are mediated by two different states, and they provide the basis for lasers that operate without a population inversion2,3,4,5,6,7. Here we report the control, by quantum mechanical tunnelling, of interference in optical absorption. The two intermediate states are resonances that arise from the mixing of the states in two adjacent semiconductors quantum wells, which are broadened by tunnelling into the same energy continuum through an ultra-thin potential-energy barrier. Inverting the direction of tunnelling by reversing the position of the barrier with respect to the two quantum wells changes the interference from destructive to constructive, as predicted theoretically. This effect might provide a way to make semiconductor lasers without population inversion8.