On the application of the Cramer-Rao and detection theory bounds tomean square error of symbol timing recovery

A modified Cramer-Rao bound is derived that takes account of the fact that the symbol timing estimate is restricted to a finite interval of one symbol duration. A detection theory bound is also applied to the symbol timing problem. Results obtained using the Cramer-Rao and detection theory bounds are compared. It is shown that the detection theory bound is superior to the traditionally used Cramer-Rao bound. In particular, the detection theory bound gives useful results for sharp pulse shapes and shows a dependence of the mean square error on the data sequence. It also yields meaningful results for small signal-to-noise ratios     

Relationship between bioceramics sintering and micro-particles-induced cellular damages

We performed experimental studies to confirm the hypothesis that cellular damages occurring around implanted biphasic bioceramics could be related to a micro-particles release because of an insufficient sintering. First, an in vitro cytotoxicity study was performed on four biphasic ceramic (BCP) samples. Without treatment of the extraction medium, a cytotoxicity was observed, although after centrifugation this cytotoxicity disappeared in all samples. Second, micro-particles of hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and 40% beta-TCP/60%HA mixture were used for a cell inhibition study. A decrease of cell viability was observed with the increase in particles concentration. At 10000 particles per cell, the viability and proliferation were completely inhibited. Third, HA, beta-TCP and BCP ceramic granules were implanted in rabbit femoral cavities for 12 weeks. No degradation of HA granules was observed. The degradation was higher for beta-TCP (40%) than for BCP (5%). On the other hand, new bone formation was significantly higher for beta-TCP (21%) and HA (18%) than for BCP (12%). More micro-particles were formed around BCP granules than around beta-TCP, and phagocytised by macrophages. The release of ceramic micro-particles could be related to the sintering process. BCP ceramic have to be sintered at only 1160 degrees C. Consequently, HA micro-particles of BCP ceramic are incompletely sintered and easily released after immersion or implantation. The microparticles could be at the origin of local inflammation and cell damage and could perhaps modify osteogenesis. Attention must be paid to this problem especially with BCP ceramics because of the sintering difficulties of this bioceramic.     

Surface normal overlap: a computer-aided detection algorithm with application to colonic polyps and lung nodules in helical CT

We developed a novel computer-aided detection (CAD) algorithm called the surface normal overlap method that we applied to colonic polyp detection and lung nodule detection in helical computed tomography (CT) images. We demonstrate some of the theoretical aspects of this algorithm using a statistical shape model. The algorithm was then optimized on simulated CT data and evaluated using a per-lesion cross-validation on 8 CT colonography datasets and on 8 chest CT datasets. It is able to achieve 100% sensitivity for colonic polyps 10 mm and larger at 7.0 false positives (FPs)/dataset and 90% sensitivity for solid lung nodules 6 mm and larger at 5.6 FP/dataset.     

Capacitive divider substation

The development of a passive damper-filter has made it possible to achieve a stable capacitive-coupling substation (SCC). This paper presents the underlying theory and analyzes the impact of the SCC on a power network system. The related nuisance phenomena (overvoltage, ferroresonance) are described together with the solutions applied. Test results are presented as proof that the nuisance phenomena have been satisfactorily eliminated: overvoltage is adequately limited at the worst node by protecting the equipment and ferroresonance never lasts more than two cycles. Lastly, the paper describes Hydro-Quebec's first such capacitive-coupling substation installed at Riviere Ste-Anne (Quebec)     

Wide-bandgap epitaxial heterojunction windows for silicon solarcells

It is shown that the efficiency of a solar cell can be improved if minority carriers are confined by use of a wide-bandgap heterojunction window. For silicon (lattice constant a=5.43 Å), nearly lattice-matched wide-bandgap materials are ZnS (a=5.41 Å) and GaP (a=5.45 Å). Isotype n-n heterojunctions of both ZnS/Si and GaP/Si were grown on silicon n-p homojunction solar cells. Successful deposition processes used were metalorganic chemical vapor deposition (MO-CVD) for GaP and ZnS, and vacuum evaporation of ZnS. Planar (100) and (111) and texture-etched ((111) faceted) surfaces were used. A decrease in minority-carrier surface recombination compared to a bare surface was seen from increased short-wavelength spectral response, increased open-circuit voltage, and reduced dark saturation current, with no degradation of the minority carrier diffusion length     

Fonction du geste interactif et du regard dans la régulation de la résponse d'écoute chez des conjoints conjugalement satisfaits et insatisfaits.

Notes that previous research has shown that spouse's responsive listening contribute to the perception of support by the partner. Videotaped conjugal support interactions of 10 maritally satisfied couples and 10 maritally dissatisfied couples were used to examine the communication regulation of spouses discussing a personal problem. Two regulators of responsive listening were studied: gaze and interactive gestures. The study objectives were (1) to compare the efficacy of gaze and interactive gestures in the regulation of responsive listening, and (2) to verify whether maritally satisfied spouses, compared with dissatisfied spouses, produced more responsive listening contingent to the regulators. The results show that the concurrent occurrences of gaze and interactive gestures were the most effective regulators of responsive listening, particularly for satisfied spouses. The results of this study underline the importance of studying responsive listening to understand the contribution of social support to marital satisfaction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Penalties of Sample-and-Sum and Weighted Partial Decision Detectors in Gaussian Noise

The deterioration in performance, measured in the probability of error sense, of sample-and-sum and weighted partial decision detectors are analyzed for arbitrary signal-to-noise ratios. These suboptimal detectors have more modest computational requirements than the optimal digital matched filter making them amenable to simple digital implementations. The effects on the penalties of the signaling waveform employed, the number of samples processed, and the signal-to-noise ratio are considered in detail. Included are the penalties for the optimum weighted partial decision detector. The optimum weighted partial decision detector is the optimum detector, in the minimum probability of error sense, for hard-limited samples. The penalty of the optimum weighted partial decision detector relative to the digital matched filter detector represents the fundamental loss in signal detectability due to hard-limiting in a sampled system.     

GaAs-based fiber-optic pressure sensor

A new sensor developed for measurement of hydrostatic pressure up to at least 100 MPa at a standard range of ambient temperatures is described. The sensor exploits the displacement of the optical absorption edge occurring in semiconductors under the influence of hydrostatic stress as a result of pressure-induced energy shifting of conduction band extrema. The sensing element is composed of an intrinsically pure GaAs single crystal configured in the form of a microprism located at the sensor tip, and attached to two multimode (50/125 μm) optical fibers designed to deliver input light to the sensor and to output a pressure-modulated light signal to the outside of a pressure region. Characterization of the sensor has been performed for pressures up to 100 MPa and for temperatures ranging from 5 to 50°C. A procedure has been proposed involving the use of two sensors (active and compensating) to minimize temperature drift through appropriate signal processing     

On the tightness of two error bounds for decision feedback equalizers

A new upper bound on the probability of error for decision feedback equalizers that is valid for serially independent and dependent stationary noise processes was presented by P. Kabaila (1987). It is shown that a bound of D.L. Duttweiler et al. (1974) is tighter than the bound of Kabaila when the noise component shows no serial dependence and with equalization over the full channel response length.<>     

A composite importance sampling technique for digital communicationsystem simulation

A new composite importance sampling technique is presented and investigated. An exact analysis is used to optimize the sample size saving and to investigate its robustness with respect to threshold settings. The composite technique offers a sample size savings of ~2.5 compared to the translation technique of D. Lu and K. Yao (1988) for memoryless systems. Applications as well as some questions for further research are discussed