Bundle sheath (BS) anatomy is found in most C4 lineages, associated with low inter-veinal distances (IVD) and high BS:mesophyll ratio (BS:MC). The origins, function and selective advantages of the BS in C3 lineages are relevant for understanding the environmental, molecular and phylogenetic determinants of C4 evolution. Suggested functions for BS have included structural support, hydraulic isolation, storage for water, ions, and carbohydrates, and photorespiratory carbon metabolism; we propose a central role for cavitation repair, consistent with the BS as a control centre on regulating stem and leaf hydraulic continuity. An analysis of BS traits in the phylogenetic lineages giving rise to C4 grasses (the 'PACMAD' clade) shows an initial enhancement in BS:MC ratio in C3 lineages, although IVD is similar to the Pooideae sister group. Using a global database, a well-developed BS in the C3 PACMAD lineages was associated with higher precipitation and temperatures in the habitat of origin on an annual basis, with the C3 to C4 progression defined by the aridity index (AI). Maintaining leaf hydraulic conductance and cavitation repair are consistent with increased evaporative demand and more seasonal precipitation as drivers, first for the C3 BS, and then C4 diversification, under declining CO2 concentrations in the Palaeogene and Neogene.

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The work reported in this paper proposes a new method for detecting Loss of Mains (LOM), which considered one of the basic protection system that should be provided for an Embedded Generator (EG). The proposed LOM protection particularly consider the case when the EG is "islanded" with part of the utility load which has a capacity close to that of the generator. It also has the capability to deal with the difficult situation related to differentiate between LOM and the loss of parallel feeder at the interfacing circuit between EG and the utility. The proposed method is based on using the Rate of Change of Voltage (dV/dt) and the change in Power Factor (∆pf) measured at the interfacing point between the EG and the utility network.

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