Optically amplified first window systems experiments

A diode pumped, commercially packaged, thulium doped fluoride fiber amplifier (TDFFA) operating in the region of 0.8 μm has been characterized. The unit is capable of producing large small signal gains, low noise figures and high saturated output powers. A power amplifier slope efficiency of 62% has been achieved at 810 nm. The same TDFFA unit was used in a series of systems experiments, at data rates of 310 Mb/s and 1.2 Gb/s, in the first telecommunications window. The results of this work indicate that data can be transmitted over ≈10 km lengths of both singlemode and standard transmission fiber, while still allowing significant margin to split the signal to a number of customers. The application of the TDFFA could therefore have significant benefit for future LAN/MAN type systems architectures involving large signal splits to customer's premises     

Measurements of frying fat deterioration: A brief review

Many factors affect the rate of deterioration of a fat used for deep fat frying. Because of the complexity of the problem, there is no single procedure which will yield reliable results in all situations. Determination of total polar materials in a frying fat provides the most reliable measure of the extent of deterioration in most cases. For monitoring a frying operation in which there is no dilution of the frying fat by the fat in the food being fried, the change in the dielectric constant is the simplest of the methods judged reliable. Free fatty acid determinations by titration and peroxide value are not recommended procedures for measuring frying fat deterioration.     

On the formalization and reuse of scientific research

The reuse of scientific knowledge obtained from one investigation in another investigation is basic to the advance of science. Scientific investigations should therefore be recorded in ways that promote the reuse of the knowledge they generate. The use of logical formalisms to describe scientific knowledge has potential advantages in facilitating such reuse. Here, we propose a formal framework for using logical formalisms to promote reuse. We demonstrate the utility of this framework by using it in a worked example from biology: demonstrating cycles of investigation formalization [F] and reuse [R] to generate new knowledge. We first used logic to formally describe a Robot scientist investigation into yeast (Saccharomyces cerevisiae) functional genomics [f₁]. With Robot scientists, unlike human scientists, the production of comprehensive metadata about their investigations is a natural by-product of the way they work. We then demonstrated how this formalism enabled the reuse of the research in investigating yeast phenotypes [r₁ = R(f₁)]. This investigation found that the removal of non-essential enzymes generally resulted in enhanced growth. The phenotype investigation was then formally described using the same logical formalism as the functional genomics investigation [f₂ = F(r₁)]. We then demonstrated how this formalism enabled the reuse of the phenotype investigation to investigate yeast systems-biology modelling [r₂ = R(f₂)]. This investigation found that yeast flux-balance analysis models fail to predict the observed changes in growth. Finally, the systems biology investigation was formalized for reuse in future investigations [f₃ = F(r₂)]. These cycles of reuse are a model for the general reuse of scientific knowledge.     

Growth of Corynebacterium bovis in mammary secretions during physiological transitions of the bovine mammary gland

An in vitro microassay was used to evaluate growth of five strains of Corynebacterium bovis in mammary secretions collected from quarters of five Holstein cows at 0, 14, and 28 d of involution, at parturition, and 14 d after parturition. Variation in growth among different strains of Corynebacterium bovis was observed. Corynebacterium bovis grew well in mammary secretions obtained at the last milking of lactation, at parturition, and 14 d after parturition. However, growth of four strains of Corynebacterium bovis in mammary secretions obtained at 14 and 28 d of involution was reduced significantly. In contrast, a streptomycin-resistant strain of Corynebacterium bovis grew well in mammary secretions obtained during involution. These data suggest that mammary secretions support growth of Corynebacterium bovis during lactation but inhibit growth during the nonlactating period. Inhibition of growth in secretions collected during the nonlactating period may be associated with the high rate of spontaneous elimination of Corynebacterium bovis intramammary infection from cessation of milking to parturition. Conversely, enhanced growth in milk may be related to persistent Corynebacterium bovis intramammary infections during lactation.     

Formation of lysinoalanine during heat treatment of milk

The heat-induced formation of lysinoalanine (LAL) was studied in raw skim milk that had been subjected to heat treatments as is usual in milk technology. Preheat treatment of milk at temperatures below 100 degrees C up to 20 min resulted in neglectable LAL amounts below 10 ppm i.p. (i.p.=in the protein) if at all. Tests with an UHT pilot plant showed that there was no proven formation of LAL with direct UHT-treatment at 110-130 degrees C for 10-25 min. In indirect UHT-treated milk vert small LAL amouints up to 50 ppm i.p. were detected only in those milk samples that were treated at temperatures high than 145 degrees C and holding times longer than 10 s. Autoclave sterilization in the range of 110-129 degrees C/10-25 min induced LAL amounts of 110 to 710 ppm i.p.. LAL formation in autoclave sterilized milk was almost directly dependent on heating temperature and time. Pre-treatment at temperatures below 100 degrees C induced no further LAL formation in any sterilization processes subsequent to preheating. In the pH range 6,50-6,90 LAL amounts in autoclave-sterilized milk increased directly with higher pH values at all temperatures. The varying degree of LAL formation with pH value was substantially more noticeable at higher than at lower temperatures. Increasing of lactose concentration caused only an insignificant decrease in LAL formation in autoclave-sterilized milk.     

Disruption of seven hypothetical aryl alcohol dehydrogenase genes from Saccharomyces cerevisiae and construction of a multiple knock-out strain

By in silicio analysis, we have discovered that there are seven open reading frames (ORFs) in Saccharomyces cerevisiae whose protein products show a high degree of amino acid sequence similarity to the aryl alcohol dehydrogenase (AAD) of the lignin-degrading fungus Phanerochaete chrysosporium. Yeast cultures grown to stationary phase display a significant aryl alcohol dehydrogenase activity by degrading aromatic aldehydes to the corresponding alcohols. To study the biochemical and the biological role of each of the AAD genes, a series of mutant strains carrying deletion of one or more of the AAD-coding sequences was constructed by PCR-mediated gene replacement, using the readily selectable marker kanMX. The correct targeting of the PCR-generated disruption cassette into the genomic locus was verified by analytical PCR and by pulse-field gel electrophoresis (PFGE) followed by Southern blot analysis. Double, triple and quadruple mutant strains were obtained by classical genetic methods, while the construction of the quintuple, sextuple and septuple mutants was achieved by using the marker URA3 from Kluyveromyces lactis, HIS3 from Schizosaccharomyces pombe and TRP1 from S. cerevisiae. None of the knock-out strains revealed any mutant phenotype when tested for the degradation of aromatic aldehydes using both spectrophotometry and high performance liquid chromatography (HPLC). Specific tests for changes in the ergosterol and phospholipids profiles did not reveal any mutant phenotype and mating and sporulation efficiencies were not affected in the septuple deletant. Compared to the wild-type strain, the septuple deletant showed an increased resistance to the anisaldehyde, but there is a possibility that the nutritional markers used for gene replacement are causing this effect.