Liposomes as Proteinase Carriers for the Accelerated Ripening of Saint-Paulin Type Cheese

The possibility of accelerated cheese ripening through addition of liposome entrapped proteinase to milk was investigated. Both enzyme encapsulation rate in liposomes and their retention in cheese were evaluated with multilamellar vesicles (MLV) and reverse-phase evaporation vesicles (REV). Using REV in Saint-Paulin type curd, no nitrogen loss was observed to the whey due to the added enzymes in liposomes. In cheese, REV produced a more progressive proteolysis during ripening than MLV did. REV addition did not lead to texture defects. Bitterness development, a critical defect in enzyme added cheese, could be delayed and minimized using REV.     

Efficient Window Block Retrieval in Quadtree-Based Spatial Databases

An algorithm is presented to answer window queries in a quadtree-based spatial database environment by retrieving all of the quadtree blocks in the underlying spatial database that cover the quadtree blocks that comprise the window. It works by decomposing the window operation into sub-operations over smaller window partitions. These partitions are the quadtree blocks corresponding to the window. Although a block b in the underlying spatial database may cover several of the smaller window partitions, b is only retrieved once rather than multiple times. This is achieved by using an auxiliary main memory data structure called the active border which requires O(n) additional storage for a window query of size n×n. As a result, the algorithm generates an optimal number of disk I/O requests to answer a window query (i.e., one request per covering quadtree block). A proof of correctness and an analysis of the algorithm's execution time and space requirements are given, as are some experimental results.     

OPTIMAL SIZING OF IRRIGATION DELIVERY SYSTEMS USING A TWO-STAGE STOCHASTIC PROGRAMMING APPROACH

In arid areas where the available water is limited and randomly changing with time, the surface irrigation might still be the best option due to economic and other considerations. Hence, the irrigation delivery system should be sized in such a way that the allocation of available surface water to different crops at any time yields maximum possible revenues. This can be ultimately achieved with the aid of a two-stage optimal formulation combining the present design stage with the future operational conditions. This work applies two stochastic mathematical techniques to determine the optimal sizes of a hypothetical surface irrigation delivery system subjected to varying deficit levels of available water and considering the uncertainties associated with the available water and the crop revenues. Canal sizes represented the first-stage decisions while the future water allocations were made in the second stage. The Regularized Stochastic Decomposition approach solved the case of stochastic available water present at the right hand side, while the L-Shaped method solved the case of stochastic second-objective coefficients associated with the crop selling prices. The L-Shaped method was also used to consider the problem of uncertain parameters in both the right hand side and the second-objective coefficients. The problem was investigated by considering a system of nine irrigation canals and six farms grown with different crops during a season of two distinctive irrigation periods. Results obtained from the stochastic formulation were compared with the corresponding ones obtained from an equivalent deterministic formulation. The comparison showed that the effect of parameter uncertainties on canal sizes and associated revenues increases with the increasing levels of deficit in water supply.     

Effect of thermophilic lactic acid bacteria on the viability of Salmonella serovar Typhimurium PT8 during milk fermentation and preparation of buffalo's yogurt

Viability of dairy-borne Salmonella enterica ssp. enterica serovar Typhimurium PT8 was studied during the fermentation of skim milk by thermophilic lactic acid bacteria (LAB). Longer generation times of Salmonella were found in mixed cultures of skim milk containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus or a mixture of them (1:1), as compared with single cultures of the pathogen. Salmonella was less able to survive in mixed cultures with these LAB during prolonged incubation at 41°C and also during cold storage of the fermented milk. L actobacillus ssp. bulgaricus and its mixture with S. thermophilus were more inhibitory to the growth and survival of Salmonella than was S. thermophilus . This was associated with higher ability of L . ssp. bulgaricus and the mixture to develop acidity in milk than S. thermophilus . Examining the antibacterial activity of these LAB towards Salmonella showed that other factors including heat-resistant and heat-labile compounds were involved in inhibiting the pathogen by these cultures. The viability of the same Salmonella strain during the preparation and cold storage of buffalo's yogurt was also examined. Salmonella was found to survive longer in yogurt made with starter containing probiotic bacteria than in that prepared with the traditional starter. This was ascribed to the development of lower pH by the traditional starter.     

Machine interference—a comparison of two patrolling methods

Tables of efficiency for a set of machines regularly patrolled by one operator have been produced. The theoretical basis of the tables has been described elsewhere. The numerical results show that unidirectional patrolling produces a small but consistent advantage over bi-directional patrolling, both in the case of manual repairs and automatic repairs which may not always be successful. This has implications for the design and layout of the machines on the factory floor. In addition, the tables can be used to determine the optimum number of machines to allocate to an operator.