Performance of two-stage discrete fiber Raman amplifiers with and without all-optical gain clamping

Using numerical simulations, we analyze the properties of two-stage discrete fiber Raman amplifiers without and with all-optical gain clamping. In both cases a two-stage amplifier can be designed to have the same gain characteristics as a single-stage amplifier with improved noise performance by use of either the same total length of gain fiber (but with increased pump power) or total pump power (but with increased total length of gain fiber).     

Novel insights into siderophore formation in myxobacteria

The myxochelins are catecholate-type siderophores produced by a number of myxobacterial strains, and their corresponding biosynthetic gene clusters have been identified in Stigmatella aurantiaca Sg a15, and Sorangium cellulosum So ce56; the latter being presented in this work. Biochemical and genetic studies described here further clarify myxochelin biosynthesis. In addition to the myxochelin A biosynthetic complex, the aminotransferase MxcL is required in order to form myxochelin B, starting from 2,3-dihydroxy benzoic acid and L-lysine. Additionally, the substrate specificity of the myxochelin A biosynthetic complex was analyzed in vitro; this led to the formation of novel myxochelin derivatives. Furthermore, MxcD was over-expressed and its function as an active isochorismic acid synthase in Escherichia coli was verified by complementation studies, as was activity in vitro. The organization of the myxochelin gene cluster of S. cellulosum So ce56 was compared to that of the Sg a15 gene cluster. The comparison revealed that although the organization of the biosynthetic genes is completely different, the biosynthesis is most probably extremely similar.     

Methods for comparing gridded inventories of atmospheric emissions--application for Milan province,Italy and the Greater Athens Area,Greece

A set of methods has been compiled to compare gridded air emission inventories that have been derived, on the same spatial grid, using widely differing techniques. Top-down and bottom-up inventories for Milan, Italy and for the Greater Athens area (GAA), Greece were used to test and apply these methods. The applicability of each method to certain source sectors was assessed by conducting sensitivity analyses. Whilst some of the methods (such as regression calculations or the Moran coefficient) appeared very sensitive to variations of point source emissions, others (e.g. the construction of difference maps) proved more appropriate for characterizing line source differences. Area sources could best be dealt with by using the newly developed acceptability criterion. The development of these tools allows a reproducible comparison of sets of emission inventories and consequently supports developments towards improvement.     

Dependability analysis of systems modeled by non-homogeneous Markov chains

The case of time non-homogeneous Markov systems in discrete time is studied in this article. In order to have measures adapted to this kind of systems, some reliability and performability measures are formulated, such as reliability, availability, maintainability and different time variables including new indicators more dedicated to electrical systems like instantaneous expected load curtailed and the expected energy not supplied on a time interval. The previous indicators are also formulated in the case of cyclic chains where asymptotic results can be obtained. The interest of taking into account hazard rate time variation, is to get more accurate and more instructive indicators but also be able to access new performability indicators that cannot be obtained by classical methods. To illustrate this, an example from an Electricité De France electrical substation is solved.     

Bioadhesive Tablets Influence of the Testing Medium Composition on Bioadhesion

A bioadhesive tablet of metronidazole has been developed for oral or vaginal administration. The bioadhesive component is poly(acrylic acid) (Carbopol 934), and the matrix component is hydroxypropyl methylcellulose (HPMC K4M). The influence of the test medium was investigated in order to determine the adhesion of the tablet during routine use by the various routes. The parameter retained to evaluate adhesion was the adhesion work on a biological tissue. The factors whose influence was investigated were pH, ionic force and nature of cations, and type of biological substrate     

Anomalous penetrant transport in glassy polymers

Summary The development of the PE/MAS ¹³C NMR spectrum of poly(d⁸MMA) cross-polarized by the protons of water is used to follow the distribution of water as it is absorbed by the polymer. In the early stages, water is in contact with the backbone CD2 and quaternary C. It makes contact with side-chain carbons later. A non-random distribution of close contacts between water and polymer molecules was also observed when P(d⁸ MMA) was precipitated from d⁸-acetone by water.Now at Varian Associates Inc., Palo Alto, CA 94303, USAThis work was supported by the Australian Research Grants Scheme and was presented in part at NMR 85, Terrigal, N.S.W. in February 1985.     

Solute and penetrant diffusion in swellable polymers: X. Swelling of multiethylene glycol dimethacrylate copolymers

The swelling behavior of copolymers containing 2-hydroxyethyl methacrylate and various multiethylene glycol dimethacrylates was examined at 25°C. These highly crosslinked copolymers show some hydrophilic behavior due to the hydroxyl groups of HEMA. Analysis of the swelling data indicates and anomalous water transport in the network, which depends on the degree of crosslinking attained according to the dimethacrylate comonomer molar fraction in the copolymerization feed. Thermomechanical analysis data were used to further characterize the network structure.     

The modified preconditioned simultaneous displacement (MPSD) method

In [4] it is shown that the Preconditioned Simultaneous Displacement (PSD) method when applied to σ₂-ordered systems of linear equations may be preferred over the Successive Overrelaxation (SOR) method in certain cases whereas it is undoubtedly superior over the symmetric SOR (SSOR) method. In this paper, we define a generalised form of PSD and the produced scheme, the Modified PSD (MPSD) method is considered for the solution of the linear system Au=b when A possesses a special form (σ₁-ordered). The analysis of convergence and the determination of optimum values for the involved parameters is presented. It is shown that if MPSD is combined with a work reduction scheme, then it may be considered competitive with SOR as the two methods possess the same rate of convergence at the optimum stage. Finally, it is proven that under these conditions PSD possesses a rate of convergence which is asymptotically twice as fast as SSOR, a result which is also valid for σ₂-ordered systems.     

French Fries oleuropein content during the successive deep frying in oils enriched with an olive leaf extract

Olive oil, sunflower oil and soybean oil were enriched with an olive (Olea Europaea) leaf extract rich in oleuropein at a supplementation level of 100 mg total phenolics per kg oil. Supplemented oils were used for deep frying of potatoes for eight successive frying sessions without replenishment under domestic frying conditions. Supplemented oils contained oleuropein while deep frying resulted in a gradual decrease in oils oleuropein content. After the eighth successive frying, oleuropein was still detected in oils, its retention being 3.2–12.4%. Deep frying of potatoes in supplemented oils succeeded in preparing French fries containing oleuropein even after eight successive fryings. Contrary to the oil type, the number of frying sessions affected potatoes oleuropein content. Oleuropein intake by consuming French fries deep‐fried in enriched oils was approximately ten times higher in potatoes prepared in the first frying session as compared to the respective intake after the eighth frying.