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.

Variability of extracellular spike waveforms of cortical neurons

Abstract: 1. Here we study the variability in extracellular records of action potentials. Our work is motivated, in part, by the need to construct effective algorithms to classify single-unit waveforms from multiunit recordings. 2. We used microwire electrode pairs (stereotrodes) to record from primary somatosensory cortex of awake, behaving rat. Our data consist of continuous records of extracellular activity and segmented records of extracellular spikes. Spectral and principal component techniques are used to analyze mean single-unit wave-forms, the variability between different instances of a single-unit waveform, and the underlying background activity. 3. The spectrum of the variability between different instances of a single-unit waveforms is not white, and falls off above 1 kHz with a frequency dependence of roughly f-2. This spectrum is different from that of the mean spike waveforms, which falls off roughly as f-4, but is essentially identical with the spectrum of background activity. The spatial coherence of the variability on the 10-micron scale also falls off at high frequencies. 4. The variability between different instances of a single-unit waveform is dominated by a relatively small number of principal components. As a consequence, there is a large anisotropy in the cluster of the spike waveforms. 5. The background noise cannot be represented as a stationary Gaussian random process. In particular, we observed that the spectrum changes significantly between successive 20-ms intervals. Furthermore, the total power in the background activity exhibits larger fluctuations than is consistent with a stationary Gaussian random process. 6. Roughly half of the single-unit spike waveforms exhibit systematic changes as a function of the interspike interval. Although this results in a non-Gaussian distribution in the space of waveforms, the distribution can be modeled by a scalar function of the interspike interval. 7. We use a set of 44 mean single-unit waveforms to define the space of differences between spike waveforms. This characterization, together with that of the background activity, is used to construct a filter that optimizes the detection of differences between single-unit waveforms. Further, an information theoretic measure is defined that characterizes the detectability.

Completion of calls to a preferred agent in an automatic call distributor

Abstract: This invention relates to methods and apparatus for completing calls to selected agents of an ACD (Automatic Call Distributor). In accordance with this invention, callers to the ACD are frequently assigned a preferred agent for handling their transactions. When these callers call the basic number of the ACD, they are identified and routed preferably, to the preferred agent if that agent is logged on. If the callers have not completed a transaction, the agent who is serving a call for that transaction provides a transaction number to the caller and the caller subsequently is connected to the agent associated with that transaction number. Advantageously, callers can normally be served by the same agent while still having the advantage of having their calls queued to any available agent of the ACD if the preferred agent for handling a caller or handling a transaction is not available.

Chemical recognition of gases and gas mixtures with terahertz waves

Abstract: A time-domain chemical-recognition system for classifying gases and analyzing gas mixtures is presented. We analyze the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses in the time domain, using digital signal-processing techniques. A simple geometric picture is used for the classification of the waveforms measured for unknown gas species. We demonstrate how the recognition system can be used to determine the partial pressures of an ammonia–water gas mixture.

Microcavity effects in organic semiconductors

Abstract: Microcavity structures containing hydroxyquinoline aluminum and diamine layers commonly used in electroluminescent devices are described. We show that it is possible to obtain emission at red, green, and blue wavelengths by changing the thickness of a polyimide filler layer in the cavity. The angular dependence of the emission wavelength and linewidth are reported and the implications for organic electroluminescent color displays are discussed.

On the Complexity of Database Queries.

Abstract: We revisit the issue of the complexity of database queries, in the light of the recent parametric refinement of complexity theory We show that, if the query size (or the number of variables in the query) is considered as a parameter, then the relational calculus and its fragments (conjunctive queries, positive queries) are classified at appropriate levels of the so-called W hierarchy of Downey and Fellows These results strongly suggest that the query size is inherently in the exponent of the data complexity of any query evaluation algorithm, with the implication becoming stronger as the expressibility of the query language increases On the positive side, we show that this exponential dependence can be avoided for the extension of acyclic queries with ? (but not <) inequalities