Models for Audiovisual Fusion in a Noisy-Vowel Recognition Task

This paper presents a study of models for audiovisual (AV) fusion in a noisy-vowel recognition task. We progressively elaborate audiovisual models in order to respect the major principle demonstrated by human subjects in speech perception experiments (the synergy principle): audiovisual identification should always be more efficient than auditory-alone or visual-alone identification. We first recall that the efficiency of audiovisual speech recognition systems depends on the level at which they fuse sound and image: four AV architectures are presented, and two are selected for the following of the study. Secondly, we show the importance of providing a contextual input linked to the Signal-to-Noise Ratio (SNR) in the fusion process. Then we propose an original approach using an efficient nonlinear dimension reduction algorithm (curvilinear components analysis) in order to increase the performances of the two AV architectures. Furthermore, we show that this approach allows an easy and efficient estimation of the reliability of the audio sensor in relation to SNR, that this estimation can be used to control the AV fusion process, and that it significantly improves the AV performances. Hence, altogether, nonlinear dimension reduction, context estimation and control of the fusion process enable us to respect the synergy criterion for the two most used architectures.     

Error control using retransmission schemes in multicast transportprotocols for real-time media

We analyze different retransmission (ARQ) schemes for error control in multicast protocols geared toward real-time, multimedia applications. We discuss why retransmission schemes are not inappropriate for such applications, but in fact can be quite effective. We present a quantitative analysis of such schemes, as well as simulation results, taking into account four different parameters (and not just the source throughput): (1) the probability of dropping a packet due to limited time for retransmissions; (2) the average time required to deliver a packet correctly to end receivers; (3) the number of times a packet will be retransmitted; and (4) the cost to the network, in terms of packet duplications, of retransmitting a packet. We reach the counter-intuitive conclusion that the optimum scheme, in terms of all four of the above parameters, in the most general scenarios (where several hosts with widely varying propagation delays and `quality of connections' are participating in the session) is to immediately retransmit packets-preferably multicast-upon reception of a NACK from any receiver. We also demonstrate, again through quantitative analysis, the circumstances under which it would be beneficial (as well as those under which it would be counter-productive) to multicast control messages in the hope of suppressing duplicates and preventing the source from being overwhelmed by control messages     

Narrowing the gap: Practical strategies for increasing whole‐grain consumption

Overcoming consumer confusion and doubt regarding nutrition recommendations is key to communicating the message to increase whole‐grain foods in the diet. Nutrition communicators may do that more successfully by using four tactics to fashion messages about whole grains: (1) present a positive message; (2) keep it short and simple; (3) keep the message practical and flexible; (4) speak with a united voice. The quantitative recommendation to eat at least three servings of whole‐grain foods daily also must be integrated into national nutrition documents, such as Healthy People 2000, Dietary Guidelines for Americans, the Food Guide Pyramid, Nutrition Recommendations for Canadians, and Canada's Food Guide to Healthy Eating, if we are to be truly successful in communicating the need to increase whole‐grain consumption.     

Adaptive space-time feedforward/feedback detection for high datarate CDMA in frequency-selective fading

We investigate linear and nonlinear space-time minimum mean-square-error (MMSE) multiuser detectors for high data rate wireless code-division multiple-access (CDMA) networks. The centralized reverse-link detectors comprise a space-time feedforward filter and a multiuser feedback filter which processes the previously detected symbols of all in-sector users. The feedforward filter processes chip-rate samples from a bank of chip-matched filters which operate on the baseband outputs from an array of antennas. We present an adaptive multiuser recursive least squares (RLS) algorithm which determines the MMSE adjusted filter coefficients with less complexity than individual adaptation for each user. We calculate the outage probabilities and isolate the effects of antenna, diversity, and interference suppression gains for linear and nonlinear filtering and for CDMA systems with varying levels of system control (e.g., timing control, code assignment, cell layout). For eight users transmitting uncoded 2-Mb/s quadrature phase-shift keying with a spreading gain of eight chips per symbol over a fading channel with a multipath delay spread of 1.25 μs, the performance of a three-antenna feedforward/feedback detector was within 1 dB (in signal-to-noise ratio per antenna) of ideal detection in the absence of interference. By training for 10% of a 5-ms frame, RLS adaptation enabled the same detector to suffer less than a 0.5-dB penalty due to the combined effects of imperfect coefficients and error propagation. The advantage of nonlinear feedforward/feedback detection over linear feedforward detection was shown to be significantly larger for a CDMA system with enhanced system control     

Fabry-Perot optical intensity modulator at 1.3 mu m in silicon

A new type of all-silicon surface-normal optical intensity modulator at 1.3 mu m is reported. It can be easily butt-coupled with a cleaved single-mode fiber. The device utilizes free-carrier effects in silicon to achieve phase modulation and a built-in Fabry-Perot cavity to convert the phase modulation into intensity modulation. A 10% modulation depth with a driving current density as low as 6*10/sup 3/ A/cm/sup 2/ was demonstrated. Because it can be easily coupled with single-mode fiber, and at the same time it is compatible with silicon technology, this device can provide an interface between silicon electronic circuitry and fiber optics in applications such as the fiber-to-home return link where system cost is a deciding figure.<>     

Reliability of local area networks with bus and ring topologies

The reliability of local area networks with bus and ring topologies with a simple transfer medium are critically analysed. A double transfer medium is used to increase reliability. The efficiencies of these approaches are compared.     

From State Machines to Temporal Logic: Specification Methods for Protocol Standards

This paper attempts to lend perspective to several different methods that have been employed for specifying computer communication protocols by comparing a spectrum of specification techniques. The paper characterizes specification languages such as state transition diagrams, variants of temporal logic approaches, and sequence expressions by the extent to Which information is encoded as properties of a single state versus properties of a history of the entire computation state sequence. Taking the prototypical alternating bit protocol as an example, each method is used to specify the requirements for the send process of the distributed system.     

Determination and occurrence of oxofatty acids in fats and oils

A relatively simple method is detailed for the routine isolation and estimation of oxofatty acids (OFA) in lipids. The lipid in cyclohexane is transmethylated in a two-phase, 3.5 min procedure, and the carbonyls in the methyl ester fraction are derivatized with 2,4-dinitrophenylhydrazine (DNPH) in the presence of monochloroacetic acid (MCA). The derivatives are fractionated on alumina, and the OFA fraction is obtained and evaluated spectrophotometrically. A large variety of animal, plant, and marine lipids contained OFA ranging from <1 to >50 μmoles/g. Data also show that (a) OFA are formed in naturally oxidizing fats and oils, and (b) strongly acidic conditions can cause elaboration of OFA in hydroperoxidized fats and oils.     

Interface dipole engineering at buried organic–organic semiconductor heterojunctions

A general technique for modifying energy level alignment at organic–organic heterojunctions is introduced, and is demonstrated here for phenyl-C₆₁-butyric acid methyl ester (PCBM) and N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD). An ultra-thin layer (∼1 nm) of TiO₂ is used as an adhesion template to attach a self-assembled monolayer of dipolar phosphonate (PA) molecules to the lower interface of a two-stack ensemble. This modification induces shifts in the vacuum level and work function over ∼1.0 eV depending on the molecular dipole moment of the PA, which in turn modifies the electronic level alignment across the organic heterojunction interface by up to 0.5 eV.     

Partial-response coding, maximum-likelihood decoding: capitalizing on the analogy between communication and recording - [History of communications]

Signal processing and coding technology for digital magnetic recording is the core technology of the channel electronics module in a hard disk drive (HDD) that processes signals read from magnetic media. In this historical review I focus on what is now widely known as partial-response, maximum-likelihood (PRML) technology, which takes advantage of the inherent redundancy that exists in signals read out of magnetic media; its theoretical foundation goes back to 1970, and it capitalizes on the analogy between high-speed data transmission and high-density digital recording, and that between a convolutional code and a partial-response signal. The first PRML-based product was introduced by IBM in 1990, and PRML technology soon became the industry standard for all digital magnetic recording products, ranging from computers' HDDs and tape drives to micro hard discs used in PCs, mobile phones, and MP3 players; use of the PRML principle has recently been extended to optical recording products such as CDs and DVDs. Its improved version, called NPML (noise-predictive, maximum-likelihood), and variants have been adopted by the HDD industry since 2000. Today, a large number of communication and information theory researchers are investigating use of advanced techniques such as turbo coding/decoding to further improve the density and reliability of both magnetic and optical recording systems.