CELL LOSS QUALITY OF SERVICE IN AN INTEGRATED TRAFFIC ATM NETWORK

This paper explores and evaluates several aspects of quality of service (QOS) in an integrated traffic ATM network. Specifically, we consider the relationships between service class definitions, usage parameter control (UPC) or policing of customer traffic, network resource allocation mechanisms, and specific network conditions under which realistic QOS limits on cell loss ratio (CLR) can be met. Traffic consists of a mixture of voice, video, image and data divided into two service classes for UPC and network resource allocation. The block oriented network simulator (BONeS) tool is used for performance evaluations. Limitations associated with evaluating very low CLR values (e.g. 10⁻⁸ and 10⁻⁶) via simulation are overcome by a hybrid simulation and extrapolation technique. It is found that these stringent QOS limits on CLR can be met for most traffic with the techniques used here, reasonable backbone trunk loads (75 per cent) and reasonable buffer sizes (200–250 cell buffers per queue). However, meeting similar limits for extremely bursty traffic (such as our image traffic model) would require extra care in network design and operation, including judicious segregation of traffic.     

EFFECT OF SOLUBLE POLYLACTIC ACID DURING REFRIGERATED STORAGE OF GROUND MEATS INOCULATED WITH ESCHERICHIA COLI O157:H71

Ground beef, ground pork, and commercial breakfast sausage were inoculated (6.5 log₁₀ CFU/mL) with a five strain mixture of Escherichia coli 0157:H7 and treated either with sterile water, or 1% or 2% solutions of soluble polylactic acid (SPLA) in sterile water and stored at 4C for 1, 24, 72 and 168 h. After 168 h, 2% SPLA was significantly (p0.05) more effective than both 1% SPLA and sterile water in reducing E. coli 0157:H7 and resulted in overall reductions of 1.68, 1.70, and 1.32 log₁₀ CFU/mL for beef, pork, and pork sausage, respectively, when compared to control samples. The meat samples treated with 1% and 2% SPLA maintained significantly (p 0.05) lower pH values throughout refrigerated storage of 168 h with the higher concentration sustaining pH values from 3.83 to 3.92. Although the inhibitory effect of this acid increased with storage time, E. coli 0157:H7 survived these acidic conditions, with water activity levels ranging from 0.972 to 0.991.     

Variability in the Quantities of Condensed Tannins and Other Major Phenols in Peach Fruit During Maturation

Quantities of condensed tannins and the major monomeric phenols were maximum between the first and second swell of fruit growth in six melting flesh peach cultivars. Quantities of tannins were higher and vanillin-proanthocyanidin ratios were lower in low quality, astringent fruit than in white or yellow flesh, commercial quality fruit. Major monomeric phenols in all cultivars were chlorogenic acid, neochlorogenic acid, isochlorogenic acid, catechin, and epicatechin. Quantities of these compounds varied by cultivar and also were greater in the low quality, astringent fruit between the first and second swell of growth.     

Selected Properties of Extruded Potato and Chicken Meat

Chicken thigh meat (CTM), (0–40%) was mixed with instant mashed potato and twin-screw extruded. Feed moisture content (FMC), (15 or 20%) and screw speed (SS) (250 or 300 rpm) were varied. CTM affected expansion, bulk density, mean cell size, plateau stress, fracturability and solubility. Protein, fat, free fatty acid and ash increased and carbohydrate decreased as CTM increased. Extrudates produced at low feed moisture (15%) had higher compressive resistance, fracturability and solubility. Extrudates produced at high feed moisture (20%) had higher bulk density and mean cell size. Screw speed had no influence except on expansion degree (p≥0.05). Increased CTM changed microstructure from rough, thread-like sheets to a flat, agglomerated carbohydrate-protein laminar phase. Panelists reported no differences in overall acceptability among 0% CTM extruded at 20% FMC, 20% CTM extruded at 15% FMC and 20% CTM extruded at 20% FMC.