Two-electrode DFB laser filter used as a wide tunable narrow-bandFM receiver: tuning analysis, characteristics and experimental FSK-WDMsystem

Characteristics of a two-electrode DFB laser filter are studied both theoretically and experimentally. Using a matrix analysis of spontaneous emission, a continuous tuning range of 6.7 Å is achieved by changing both net field gains of the two electrodes. A total discontinuous tuning range of over 10 nm comprising alternating mode jumps and continuous tuning range of 4 Å are measured experimentally. The laser filter presents a FWHM bandwidth of 5 GHz which depends on the optical input power. In addition, it is demonstrated that a DFB laser filter can act as a frequency discriminator/photodetector, i.e., a narrow-band FM receiver, with a uniform bandwidth of 1.5 GHz. Using the two-electrode DFB laser for both transmitter and receiver, a two-channel FSK-WDM transmission system utilizing the discontinuous tuning range is reported. The advantage of such a device is the simplicity as compared to the heterodyne technique     

On visual servoing based on efficient second order minimization

This paper deals with the Efficient Second order Minimization (ESM) and the image-based visual servoing schemes. In other words, it deals with the minimization based on the pseudo-inverse of the mean of the Jacobians or on the mean of Jacobian Pseudo-inverses. Chronologically, it has been noticed in Tahri and Chaumette (2003) [22] that ESM generally improves the system behavior when compared with the system in which only the simple Jacobian Pseudo-inverses are used. Subsequently, a mathematical explanation has been given in Malis (2004) [12]. In this paper, the proofs given by Malis are discussed and it will be shown that there is a limitation to the validity of the ESM. We will also show that the use of ESM does not necessarily ensure a better system behavior, especially in the situations where large rotational motions are involved. Further, a new appropriate formula of the ESM is proposed and validated using several kinds of features.     

Robust image-based visual servoing using invariant visual information

This paper deals with the use of invariant visual features for visual servoing. New features are proposed to control the 6 degrees of freedom of a robotic system with better linearizing properties and robustness to noise than the state of the art in image-based visual servoing. We show in this paper that by using these features the behavior of image-based visual servoing in task space can be significantly improved. Several experimental results are provided and validate our proposal.     

Antioxidant and anticholinesterase activity of essential oils and ethanol extracts of <Emphasis Type="Italic">Thymus algeriensis</Emphasis> and <Emphasis Type="Italic">Teucrium polium</Emphasis> from Algeria

This study aimed to investigate the cholinesterase (ChE) inhibitory and antioxidant activities of essential oil (EO) and ethanolic extract (EE) of two Lamiaceae medicinal plants from Algeria: Thymus algeriensis Boiss. & Reut. and Teucrieum polium subsp capitatum. The chemical composition of EOs analyzed by GC and GC–MS revealed the presence of carvacrol (43.2%), p-cymene (18.7%) and γ-terpinene (14.8%) as major compounds in T. algeriensis, while germacrene D (25.0%), bicyclogermacrene (10.4%), β-pinene (11.3%) and spathulenol (5.8%) were the most important components in T. polium oil. The best inhibitory activity on acetylcholinesterase (AChE) was exhibited by the EO of T. algeriensis. On the other hand, T. polium oil was more efficient against butyrylcholinesterase (BChE) than against AChE, whereas EEs showed weak or no inhibitory effect, particularly against AChE. Antioxidant activity was evaluated by β-carotene bleaching, ferric and cupric reducing powers and inhibition of ABTS^?+, DPPH^? and superoxide radicals. EOs showed different antioxidant trends depending on the assay used while ethanol extracts had high activity with all tests.     

Cocaine craving, euphoria, and self-administration: A preliminary study of the effect of catecholamine precursor depletion.

The authors used the acute phenylalanine-tyrosine depletion (APTD) method to test the effect of transient catecholamine precursor depletion on cocaine craving, euphoria, and self-administration. Eight nondependent, nontreatment-seeking cocaine users self-administered 3 doses of cocaine (0.6, 1.5, 3.0 mg/kg, taken intranasally) following ingestion of (a) a nutritionally balanced amino acid mixture, (b) APTD, and (c) APTD followed by L-dopa/carbidopa (2 × 100 mg/25 mg). APTD decreased both cue and cocaine-induced drug craving but not euphoria or self-administration. APTD + L-dopa also decreased drug craving, possibly reflecting the ability of L-dopa to transiently decrease dopamine cell firing. Together, these preliminary results suggest that the craving elicited by cocaine and cocaine cues is related to changes in catecholamine neurotransmission. Euphoria and the self-administration of freely available drugs by regular users, in comparison, might be better accounted for by other mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Involvement of trihydroxyconjugated bile salts in cholesterol assimilation by bifidobacteria

BACKGROUND: We assessed diurnal variation in the direction of mood switches in a sample of outpatients with rapid-cycling bipolar disorder who were on stable medication regimens. We predicted that patients would be more likely to switch from depression into mania or hypomania during the daytime hours and from mania/hypomania into depression overnight. METHOD: Fifteen patients with rapid-cycling bipolar disorder completed self-rated mood scales twice a day: once shortly after awakening and once at bedtime. Using 3 months of data for each patient, we performed categorical analyses (McNemar chi-square) to study the direction of mood switches between each day's morning and evening rating and between each evening rating and the subsequent morning rating. RESULTS: As predicted, switches that occurred between the morning and evening ratings were more likely to be from depression into mania/ hypomania or euthymia (64.3%) than in the opposite direction (35.6%; p < .0001). Similarly, switches that occurred between the evening rating and the next morning's ratings were more likely to be from mania/hypomania or euthymia into depression (64.8%) than in the opposite direction (35.2%; p < .0001). CONCLUSION: Extended wakefulness, exposure to light, increased activity, and/or endogenous rhythms could contribute to the elevation of mood during the course of the day. Sleep, darkness, reduced activity, and/or endogenous rhythms could contribute to the tendency to switch into depression overnight. Clinicians should attend to the time of day that clinical assessments are performed in patients with rapid-cycling bipolar disorder. Potential therapeutic implications include the use of light or activity during depression and use of induced sleep or exposure to darkness during mania/hypomania.     

Wavelength reuse scheme in a WDM unidirectional ring network usinga proper fibre grating add/drop multiplexer

An experimental optical WDM ring network is proposed. It uses a proper add/drop multiplexer based on a fibre grating filter. Both-way transmission using a wavelength reuse scheme is successfully demonstrated without any crosstalk     

Dynamic Modeling of a Class of Continuum Manipulators in Fixed Orientation

A novel simultaneous localization and mapping (SLAM) technique based on independent particle filters for landmark mapping and localization for a mobile robot based on a high-frequency (HF)-band radio-frequency identification (RFID) system is proposed in this paper. SLAM is a technique for performing self-localization and map building simultaneously. FastSLAM is a standard landmark-based SLAM method. RFID is a robust identification system with ID tags and readers over wireless communication; further, it is rarely affected by obstacles in the robot area or by lighting conditions. Therefore, RFID is useful for self-localization and mapping for a mobile robot with a reasonable accuracy and sufficient robustness. In this study, multiple HF-band RFID readers are embedded in the bottom of an omnidirectional vehicle, and a large number of tags are installed on the floor. The HF-band RFID tags are used as the landmarks of the environment. We found that FastSLAM is not appropriate for this condition for two reasons. First, the tag detection of the HF-band RFID system does not follow the standard Gaussian distribution, which FastSLAM is supposed to have. Second, FastSLAM does not have a sufficient scalability, which causes its failure to handle a large number of landmarks. Therefore, we propose a novel SLAM method with two independent particle filters to solve these problems. The first particle filter is for self-localization based on Monte Carlo localization. The second particle filter is for landmark mapping. The particle filters are nonparametric so that it can handle the non-Gaussian distribution of the landmark detection. The separation of localization and landmark mapping reduces the computational cost significantly. The proposed method is evaluated in simulated and real environments. The experimental results show that the proposed method has more precise localization and mapping and a lower computational cost than FastSLAM.     

Detailed modeling of the evaporation and thermal decomposition of urea‐water solution in SCR systems

This work is aimed to develop a multicomponent evaporation model for droplets of urea‐water solution (UWS) and a thermal decomposition model of urea for automotive exhausts by using the selective catalytic reduction systems. In the multicomponent evaporation model, the influence of urea on the UWS evaporation is taken into account using a nonrandom two‐liquid activity model. The thermal decomposition model is based on a semidetailed kinetic scheme accounting not only for the production of ammonia (NH₃) and isocyanic acid but also for the formation of heavier solid by‐products (biuret, cyanuric acid, and ammelide). This kinetics model has been validated against gaseous data as well as solid‐phase concentration profiles obtained by Lundstroem et al. (2009) and Schaber et al. (2004). Both models have been implemented in IFP‐C3D industrial software to simulate UWS droplet evaporation and decomposition as well as the formation of solid by‐products. It has been shown that the presence of the urea solute has a small influence on the water evaporation rate, but its effect on the UWS temperature is significant. In addition, the contributions of hydrolysis and thermolysis to urea decomposition have been assessed. Finally, the impacts of the heating rate as well as gas‐phase chemistry on urea decomposition pathways have been studied in detail. It has been shown that reducing the heating rate of the UWS causes the extent of the polymerization to decrease because of the higher activation energy. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Nouvelle expression temporelle de ľimpédance interne des conducteurs à section rectangulaire

In this paper, a new time domain internal impedance formula for characterizing the skin effect in interconnects of rectangular cross section is proposed. The comparison with the simulation results of a method involving frequency domain exact formula validates the present model and illustrates its accuracy. We have also shown the lack of precision of the formulations based on conductor losses varying as √ f In order to predict the responses of lossy planar transmission lines, the used methods are the time domain — frequency domain transformation (tdfd) and the finite difference time domain algorithm (fdtd). Theses techniques of analysis are applied to the mtl equations under quasi — tem approximation.