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     

Full Film, Boundary Lubrication and Tribochemistry in Steel Circular Contacts Lubricated with Glycerol

In this article, the lubricating properties of pure glycerol are investigated under both mild and severe EHL regimes. Amazingly low friction coefficients (about 0.01) are reported by experiments in thick film regimes compared to traditional base oils. EHL calculations of film thickness and friction (including thermal effects) predict friction coefficients that are twice those actually found for glycerol. Chemical analysis of glycerol before and after the friction tests were performed by NMR and Karl Fischer methods, and they reveal that water is produced by tribochemical reaction as well as other species like aldehydes. This finding is in agreement with a corrosion pattern observed inside the wear scars of the steel samples. This study provides an explanation to the anomalously low friction observed in the thick film regime. In fact, water produced in the lubricant decreases traction forces due to the drastic decrease of the viscosity of glycerol with water addition.     

Reconstruction of 3D ion beam micro-tomography data for applications in Cell Biology

The DISRA (Discrete Image Space Reconstruction Algorithm) reconstruction code, created by A. Sakellariou, was conceived for the ideal case of complete three-dimensional (3D) PIXET (Particle Induced X-ray Emission Tomography) data. This implies two major difficulties for biological samples: first, the long duration of such experiments and second, the subsequent damage that occurs on such fragile specimens. For this reason, the DISRA code was extended at CENBG in order to probe isolated PIXET slices, taking into account the sample structure and mass density provided by 3D STIMT (Scanning Transmission Ion Microscopy Tomography) in the volume of interest. This modified version was tested on a phantom sample and first results on human cancer cells are also presented.     

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)     

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     

A comparison of cellular irradiation techniques with alpha particles using the Geant4 Monte Carlo simulation toolkit

A comparison of three cellular irradiation techniques using the Monte Carlo simulation toolkit Geant4 is presented in this paper. They involve electrodeposited source of alpha particle-emitting radionuclides, random classical alpha beam irradiation and single cell targeted irradiation using a focused alpha microbeam line. The simulation allows the calculation of hit distributions among the cellular population as well as the absorbed dose for two typical cellular geometries.     

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.     

Thermal Elastohydrodynamic Lubrication of Point Contacts Using a Newtonian/Generalized Newtonian Lubricant

The classical ElastoHydroDynamic (EHD) theory assumes a Newtonian lubricant and an isothermal operating regime. In reality, lubricating oils do not behave as perfect Newtonian fluids. Moreover, in most operating conditions of an engineering system, especially at high speeds, thermal effects are important and temperature can no longer be considered as constant throughout the system. This is one reason why there has always been a gap between numerical results and experimental data. This paper aims to show that this gap can be reduced by taking into consideration the heat generation that takes place in the contact and using appropriate rheological models. For this, a unique thermal ElastoHydrodynamic lubrication model is developed for both Newtonian and non-Newtonian lubricants. Pressure, film thickness and traction results are then compared to their equivalent isothermal results and experimental data. The agreement between thermal calculations and experiments reveals the necessity of considering thermal effects in EHD models.