Polarization independent bulk active region semiconductor optical amplifiers for 1.3 /spl mu/m wavelengths

Semiconductor optical amplifiers for 1.3 /spl mu/m are realized combining single-step grown bulk InGaAsP active region with ridge-waveguides. Achieved fiber-to-fiber gains are in excess of 27 dB with spectral ripples below 0.2 dB. Gain is polarization insensitive to within 1 dB over the entire range of driving current, 1.28 /spl mu/m to 1.34 /spl mu/m wavelength and 10/spl deg/C to 50/spl deg/C heat sink temperature. Intrinsic noise figure is 6.3 dB. Gain saturates at +10 dBm.     

Genetic differences in ethanol drinking of the rat following injection of 6-OHDA, 5,6-DHT or 5,7-DHT into the cerebral ventricles

The preference characteristics for ethanol of four different strains of rats were determined in a two-choice situation by offering water and ethanol in a concentration which was increased from 3 to 30% over a 12-day test sequence. Using stereotaxic procedures, 50 mug 5,6-dihydroxytryptamine (5,6-DHT), 200 mug 6-hydroxydopamine (6-OHDA) or 100 mug 5,7-dihydroxytryptamine (5,7-DHT) were then injected acutely into the lateral cerebral ventricle in a 20 mul volume. Rats of the Sprague-Dawley strain increased their ethanol preference following the lesioning of the serotonergic system by 5,6-DHT, whereas similar destruction of catecholaminergic neurons by 6-OHDA markedly suppressed ethanol intake; Long-Evans rats displayed a similar trend in ethanol drinking patterns. However, animals of the Holtzman strain manifested the increased drinking after 5,6-DHT, but showed no suppression of drinking following 6-OHDA. The preference of rats of the Wistar strain was unaffected by 5,6-DHT but attenuated by 6-OHDA. 5,7-DHT had little or no effect on ethanol consumption in any of these strains. These findings thus suggest that genetic factors are an important determinant in an animal's response to a drug that affects 5-HT or NE systems in the brain, particularly when ethanol selection is investigated.     

Etude de la reaction d'oxydo-réduction de l'aluminium dans des bains de chlorures alcalins fondus

Résumé Dans le présent travail nous étudions la réaction d'oxydo-réduction de l'aluminium dans l'eutectique fondu NaCl–KCl–LiCl à 723 K en se penchant plus particulièrement sur le problème de la détermination de la valeur du nombre,n, d'électrons échangés au cours de cette réaction. Deux types d'expériences sont réalisées, tout d'abord des déterminations de l'activité des ions aluminium par mesure de fém, puis des mesures de cinétique à l'aide de la méthode chronopotentiométrique sur une électrode d'argent. Nous avons constaté que l'analyse des courbes provenant de ces méthodes nécessite la connaissance des coefficients d'activité ainsi que la variation du coefficient de diffusion, en fonction de temps pour en déduire une valeur den. La prise en compte de ces paramètres au cours de l'analyse des chronopotentiogrammes obtenus, conduit à des valeurs den voisines de 3 conformément à la réaction d'oxydo-réduction de l'aluminium.

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A study of the redox reaction of aluminium in a NaCl–KCl–LiCl melt at 723 K has been carried out with particular emphasis on the problem of determination of the number of electrons,n, exchanged during this reaction. Two types of experiments were performed, initially the determination of the aluminium ion activity by e.m.f. measurement and, secondly, investigation of the reaction kinetics using chronopotentiometry on a silver electrode. For analysis of the curves resulting from this method, a knowledge of the activity coefficients and of the variation of the diffusion coefficient with time is needed in order to derive a value forn. Taking into account these parameters, a value ofn approximately equal to 3 was obtained for the aluminium redox reaction.

     

Misalignment problem in matrix decomposition with missing values

Data collection within a real-world environment may be compromised by several factors such as data-logger malfunctions and communication errors, during which no data is collected. As a consequence, appropriate tools are required to handle the missing values when analysing and processing such data. This problem is often tackled via matrix decomposition. While it has been successfully applied in a wide range of applications, in this work we report an issue that has been neglected in literature and “degenerates” the quality of the imputations obtained by matrix decomposition in multivariate time-series (with smooth evolution). Briefly, the problem consists of the misalignment of the matrix decomposition result: the missing values imputations fall within an incorrect range of values and the transitions between observed and imputed values are not smooth. We address this problem by proposing a post-processing alignment strategy. According to our experiments, the post-processing adjustment substantially improves the accuracy of the imputations (when the misalignment occurs). Moreover, the results also suggest that the misalignment occurs mostly when dealing with a small number of time-series due to lack of generalization ability.

     

Generation of complete test suites from mealy input/output transition systems

Model-based testing overcomes challenges in software testing by generating automated test cases from behavior models, e.g. finite state machine (FSM) and input/output transition system (IOTS). Despite the existence of methods for IOTSs, the problem of selection of test cases is an important and difficult topic. The current methods from IOTSs do not provide the same support offered by the existing theory for FSMs, as complete fault coverage. In this paper, we propose a test generation method for IOTSs based on the W method developed for FSMs. The basic idea is to generate a transition cover set and a characterization set and concatenate them to generate complete test suites for IOTSs in a bounded number of steps. The method generates test suites with complete fault coverage for a given fault domain and is targeted at a class of IOTSs, called mealy IOTS, which accepts inputs only in stable states. Results from a case study show the proposed algorithm can achieve better results than a classical method for IOTSs.