Article history: Received 23 March 2017 Received in revised form 8 May 2017 Accepted 18 May 2017 Polycrystalline advanced ceramics is a synthetic product produced by sintering together selected carbide or other tough material grains in a metal matrix. Due to wide and sensitive application of these materials, the accurate and efficient determination of the associated fracture mechanisms is of fundamental importance to material manufacturers and end users alike. An experimental investigation of two different grades of advanced ceramics was performed. The material was found to follow a thermal-decohesion model suggesting that adiabatic conditions occur at the crack tip during fracture.

Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is the case for the giant root-rat Tachyoryctes macrocephalus endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root-rats on various ecosystem features within a 3.5-ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in 2 periods of a year. The root-rats altered plant species composition, reducing the dominant forb, Alchemilla abyssinica, while enhancing Salvia merjame and a few other species, and reduced vegetation cover, but not the fresh plant biomass. Where burrows were abandoned by root-rats, other rodents took them over and A. abyssinica increased again. Root-rat burrowing created small-scale heterogeneity in soil compactness due to the backfilling of some unused burrow segments. Less compacted soil tended to be rich in nutrients, including carbon, nitrogen and phosphorus, which likely affected the plant growth on sites where the vegetation has been reduced as a result of root-rat foraging and burrowing.

Abstract Lower leg exercises are impacted by the anatomy of the triceps surae-Achilles tendon complex. Such exercises may utilize series elastic energy (SEE), temporarily stored within the Achilles tendon, to augment forces exerted by the triceps surae. While SEE's contribution to bipedal jumping and walking have been assessed, other lower leg exercises yet to receive similar scrutiny include seated calf presses done on flywheel-based hardware. Current subjects did two identical calf press workouts on a flywheel ergometer. The following three variables were obtained from workouts–the total work (TW) performed, net energy costs, and peak blood lactate concentration ([BLa−]). With multivariate regression, four variables correlated with each criterion measures’ variance–lower leg length (LLL) and cross-sectional area (CSA), as well as the lengths of the triceps surae (ML) and Achilles tendon (ATL). Our predictor variables correlated to significant amounts of TW and net energy cost, but not [BLa−] variance. Univariate matrices showed CSA was the best overall predictor for our criterion measures, while ML and ATL were generally weaker correlates. ATL did not have as great an impact as with other lower leg exercises; likely because the slow rate of ankle joint movement greatly limited SEE activity. The limited degree of foot support for ergometer repetitions was also a factor that likely weakened ATL's impact as a correlate. More research on anatomy's impact on this novel form of exercise is warranted.