Work flow control in the flexible flow line

This research involves the development and evaluation of a part flow control model for a type of flexible manufacturing system (FMS) called a dedicated flexible flow line (FFL). In the FFL, all part types flow along the same path between successive machine groups. The specific objective of the part flow control model for the FFL is to minimize makespan for a given set of parts produced in a FFL near-term schedule, given fixed available buffer constraints. The control model developed in this research involved the repeated, real-time execution of a mathematical programming algorithm. The algorithm attempts to release the right mix of parts at the tight time to keep the FFL operating smoothly. The focus of the approach is directed toward managing WIP buffers for each machine group queue. The algorithm specifically incorporates stochastic disturbance factors such as machine failures. Through a limited number of simulation experiments, performance of the control model is shown to be superior to other parts releasing and control methods reported in the literature.     

Schistosoma mansoni: Cercarial degradation of a radioactively labeled collagen gel

The apparent penetration activity of Schistosoma mansoni cercariae was quantified by means of an in vitro assay with a radioactively labeled Type I collagen gel. Both live cercariae and cercarial preacetabular gland secretions degraded the collagen. The addition of skin lipid or linoleic acid to the gel surface enhanced the degradation by live cercariae.     

Leucocytosis in Biomphalaria glabrata sensitized and resensitized to Echinostoma lindoense

Leucocytosis was shown to occur in the pulmonate gastropod Biomphalaria glabrata exposed to the trematode Echinostoma lindoense. In these sensitized snails, the leukocyte count in the hemolymph was elevated 3 to 5 days postexposure to miracidia, and prior to complete encapsulation of sporocysts. This increase continued 1 to 5 days after destruction of sensitizing, irradiated E. lindoense sporocysts. Counts returned to normal levels after this period. A significant and more rapid increase in numbers of circulating leukocytes occurred 1 to 6 hr after reexposure of snails to a sensitizing dose of nonirradiated E. lindoense sporocysts. The leukocyte counts usually returned to normal levels after this period, except in snails in which some resensitizing sporocysts remained alive.     

Idiotypic analysis of anti-GAT antibodies. VII. Common idiotype on hybridoma antibodies to poly(Glu60 Ala40)

A single DBA/2 mouse, immunized with L-glutamic acid60-L-alanine40 (GA), was used to produce hybridoma cell lines. Seven hybridoma anti-GA antibodies were obtained for idiotypic analyses. Two hybridoma anti-L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT) antibodies, preferentially reactive to GA, were studied in parallel. Anti-idiotypic antisera to purified anti-GAT and anti-GA serum antibodies and to hybridoma anti-GA antibodies were analyzed by idiotype binding and inhibition of idiotype binding assays. Five of the nine hybridoma antibodies exhibited common GA-1 idiotypic specificities previously demonstrated on the majority of anti-GA antibodies of inbred mouse strains of differing immunoglobulin heavy chain linkage groups; these hybridoma antibodies also possessed private idiotypic determinants. Two GA-1 negative hybridoma anti-GA antibodies appeared identical by immunochemical criteria, arguing that somatic hybridization does not artifactually generate private idiotypic determinants. The results demonstrate that the common GA-1 idiotype system is associated with a family of nonidentical but idiotypically related antibody molecules present in a single DBA/2 mouse, and these antibodies are part of the "GA-1 idiotypic family".     

On the carbon and sulphur metabolism in the meromictic Lake Faro (Sicily)

The processes of photosynthesis, chemosynthesis and sulphate reduction were quantitatively studied in the brackish meromitic lake Faro (Sicily) with the aid of C¹⁴ and S³⁵. The layer of “red water” was situated at the depht of the chemocline (13–14 m), where the average concentration of H₂S was 10 mg/l. The total biomass of bacterioplankton consisted in this layer mostly of a brown Chlorobium which reached a wet weight of 30 g/m³. The production of photosynthesis in this layer was 30–60 µg C/l/day. The microbial population in the “red water” was found adapted to an extremely low light intensity and to show a light optimum at the depth µg 9m where only 2,5% of outside light penetrates. The photoautotrophic microflora is consumed by infusoria found in mass in the “red water” layer. An active H₂S-production was found in the water column in the upper part of the H₂S-zone and in the bottom sediments. The data are discussed from the view point of the trophology of meromitic basins.     

How honeybee queen attendants become ordinary workers

Honeybee queen attendants disperse queen pheromones to supplement pheromone dispersal by direct queen-worker contacts. With time they lose their dispersal function exponentially due mainly to volatilization of queen pheromones carried on their bodies. The elimination of those airborne pheromones together with the air while ventilating the hive is balanced by pheromone release by the queen. This equilibrium results in a certain level of queen pheromones in the broodnest. The change of the pheromone level (for example, due to loss of the colony of its queen) can serve as a signal to alter the behaviour of the workers and the state of the colony.     

Use of perfluorocarbon emulsions in cell culture.

Perfluorocarbon emulsions were applied to hybridoma cultures grown in tissue culture tubes and column bioreactors. The oxygen transfer enhancement effect of perfluorocarbon emulsions was clearly demonstrated by the higher cell densities obtained in emulsion-supplemented systems. In addition, perfluorocarbon emulsions were shown to provide better cell suspension in a low-shear environment. The study in column bioreactors also suggested a cell protective effect of the employed perfluorocarbon emulsions in reducing the damage to cells by gas bubbles.