During autumn senescence, plants must disassemble the photosynthetic apparatus as nutrients are remobilized from the leaves. The goal of this study was to examine changes in relative abundance of photosynthetic proteins and pigments throughout autumn senescence in order to understand the mechanisms of photoprotection used during this process. We sampled leaves from two deciduous tree species [sugar maple (Acer saccharum Marsh.) and swamp white oak (Quercus bicolor Willd.)] throughout autumn during 2010 and 2013. Chlorophyll fluorescence was measured, thylakoids were isolated for western blotting with antibodies to individual proteins and pigment content was assessed. Both species retained high photochemical efficiency until late autumn and showed earlier onset of degradation of photosystem I relative to photosystem II. The species differed in the timing and pattern of degradation of individual photosynthetic proteins and pigments. In maple, there were increases in anthocyanins, more rapid degradation of light-harvesting proteins and enrichment of xanthophyll cycle pigments in late autumn. In oak, light-harvesting proteins were retained in higher abundance throughout autumn, PsbS levels increased during early autumn and lutein was enriched in late autumn samples. The results suggest that the species differ in strategies for photoprotection during autumn senescence.

The goal of the present project is to build a multidisciplinary, rapid, robust, and accurate computational tool to optimize wing-mounted propeller designs. The full Farassat's formulation F1A for aeroacoustic analysis is implemented in the open-source software SU2. This extension enables the prediction of far-field noise generated by moving sources. The formulation is verified, for a stationary and rotating sphere in a wind tunnel and for a tiltrotor in forward flight, by comparing the acoustic predictions of SU2 with the predictions computed by NASA's aeroacoustics code ANOPP2. The algorithmic differentiation capability of SU2 provides discretely consistent, adjoint-based sensitivity analysis for this formulation. The adjoint-based sensitivities are verified through comparison with complex-step sensitivities.

Squeeze film flow occurs when two surfaces move in a normal direction relative to each other and is a phenomenon of importance to many engineering systems, from macro to microscale. Squeeze film damping is widely used in large‐scale rotating machinery but even more so presently in microsystems. In the latter case, for modelling purposes, the two surfaces producing the squeeze film flow are typically assumed perfectly parallel, which is often not the case in practice. This paper presents a general formula for squeezing flow between two rigid surfaces for both parallel and tilted configurations in the 1‐dimensional case (2‐dimensional flow). The solution is derived from the Reynolds equation. The results in the parallel case compare favorably to previous literature data. A case study is presented for plates with dimensions characteristic of microelectromechanical systems. The important contribution of this paper is to isolate and study this “tilt effect” which can contribute to discrepancies and confusion in interpreting squeeze film behaviour, particularly at the microscale.