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Combat aircraft operations are usually constrained by limits on the logistics resources available. However, models that can compute the logistics resources necessary to support planned combat aircraft activity typically are custom applications that are data-intensive and difficult to use. This paper introduces a method for the Argentine Air Force (AAF) to estimate the mean number of aircraft that can be restored in a given time between consecutive sorties, given specified maintenance resources and base physical geometry. This maintenance resources evaluation technique (MRET) uses an analytical approach to estimate the mean and variance of aircraft unscheduled downtime. These parameters are then used in a Monte Carlo simulation of scheduled and unscheduled maintenance tasks necessary to prepare aircraft for the next sortie. When programmed in a spreadsheet, the MRET combines a high response speed with a moderately detailed scenario description, making the model suitable for the AAF. [ABSTRACT FROM AUTHOR]

Bone loading was quantified, using in vivo strain recordings, in the tibiotarsus of growing chicks at 4, 8, 12, and 17 weeks of age. The animals were exercised on a treadmill at 35% of their maximum running speed for 15 minutes/day. In vivo bone strains were recorded at six sites on the tibiotarsus. Percentages of the bone's length and a percentage of top running speed were used to define functionally equivalent sites on the bone, and a consistent exercise level over the period of growth was studied. The pattern of bone strain defined in terms of strain magnitude, sign, and orientation remained unchanged from 4-17 weeks of age, a period when bone mass and length increased 10-fold and threefold, respectively. Our findings support the hypothesis that bones model (and remodel) during growth to achieve and maintain a similar distribution of dynamic strains at functionally equivalent sites. Because strain magnitude and sign (tensile versus compressive) differed among recording sites, these data also suggest that cellular responses to strain-mediated stimuli differ from site to site within a bone. [ABSTRACT FROM AUTHOR]