Simultaneous optimization scheduling with two agents on an unbounded serial-batching machine

This paper considers a class of simultaneous optimization scheduling with two competitive agents on an unbounded serial-batching machine. The cost function of each agent depends on the completion times of its jobs only. According to whether the jobs from different agents can be processed in a common batch, compatible model and incompatible model are investigated. For the incompatible model, we consider batch availability and item availability. For each problem, we provide a polynomial-time algorithm that can find all Pareto optimal schedules.

Retrospective and prospective prioritization in visual working memory

A growing body of research indicates that items assigned with a higher ‘value’ prior to presentationare better recalled in working memory tasks. This has been interpreted as reflecting the strategic prioritization of these items via selective attention during encoding, maintenance, and retrieval. The current study sought to establish whether value-based prioritization effects can be obtained in a sequential visual working memory task when value information is provided retrospectively during maintenance and items are no longer present in the environment. Enhanced recall of high value items along with costs to low value items (relative to equal value trials) was observed, although the high value benefit was only reliably found on the final sequence position. In comparison, a follow- up experiment in which values were provided prior to presentation found large prioritization benefits across sequence positions. This study illustrates that attention can be retrospective shifted between working memory representations based on value, but the effectiveness of this strategic process depends on item availability and accessibility, either in the environment or in working memory.

Staple Food Item Availability among Small Retailers in Providence, RI

Inventory requirements for authorized Supplemental Nutrition Assistance Program (SNAP) retailers have undergone several revisions to increase the availability of healthful foods. A proposed rule of 84 staple food items was not implemented due to concerns that stores would not withstand this expansion, resulting in a final rule requiring 36 items. This study used the Food Access Research Atlas data to characterize food provisions in 30 small retailers in areas with high and low proportions of SNAP and racial minority residents in Providence, Rhode Island (RI). Stores were assessed with an audit instrument to tally variety, perishability, and depth of stock of four staple food categories. Descriptive, analysis of variance, and chi-square analyses were performed. Across stores, 80% were compliant with the final rule, but 66.7% would need to expand their offerings to meet the proposed rule. Mean dairy variety was lowest among all categories (p < 0.05). Most stores met the perishability (92.3%) and depth-of-stock requirements (96.1%) under both rules. No difference was detected between areas with high and low proportions of SNAP and racial minority residents. Future expansion of requirements may increase healthful food availability without imposing undue burdens on retailers in Providence, RI, excluding increased requirements for dairy variety.

Food, alcohol and cigarette availability and consumption in Almaty, Kazakstan: results and appraisal of a rapid assessment

Objectives:(1) To develop a useful tool to measure food, alcohol and tobacco items; (2) to document the availability of these items in Almaty, Kazakstan; (3) to describe the relationship between consumption and availability; and (4) to identify possible relationships between availability and health outcomes in the city and region.Design:A survey of 648 vendors in Almaty, Kazakstan was conducted over one month from December 1999 to January 2000. Vendors identified which items they sold from a list of 61 food, alcohol and tobacco items.Setting:Vendors were approached in three of the six regions of Almaty, Kazakstan. Regions canvassed included Auzov, one of the three ‘sleeping regions’; Medeo, one of the two downtown regions; and Turksib, a more suburban/rural area of the city.Results:There was a significant correlation between alcohol and cigarette consumption and availability. The relative availability of items was numerically and spatially consistent throughout the city. Fruits and vegetables occurred infrequently (<20% of sites) and in relative isolation from the rest of the system, while candy and cigarettes occurred with a higher relative frequency (75–80% of sites). Maps of vendors showed clusters around geographical features such as major roads and intersections.Conclusions:Combining a checklist and mapping tools provides a model of consumer item availability that can help identify priorities for public health and urban planning professionals. The wide availability of cigarettes, alcohol, candy, coffee and tea, and limited availability of fruits, vegetables and whole grains, is likely to support increasing rates of chronic disease in Almaty.