58 research outputs found
Charged particle sources for implantation and surface reactions Final report
High temperature ion source developed for implantation and surface reactions of Ar, Pb, and Ga ion
Pollinator or pedigree:Which factors determine the evolution of pollen nutrients?
A prime example of plant-animal interactions is the interaction between plants and pollinators, which typically receive nectar and/or pollen as reward for their pollination service. While nectar provides mostly carbohydrates, pollen represents the main source of protein and lipids for many pollinators. However, the main function of pollen is to carry nutrients for pollen tube growth and thus fertilization. It is unclear whether pollinator attraction exerts a sufficiently strong selective pressure to alter the nutritional profile of pollen, e.g., through increasing its crude protein content or protein-to-lipid ratio, which both strongly affect bee foraging. Pollen nutritional quality may also be merely determined by phylogenetic relatedness, with pollen of closely related plants showing similar nutritional profiles due to shared biosynthetic pathways or floral morphologies. Here, we present a meta-analysis of studies on pollen nutrients to test whether differences in pollen nutrient contents and ratios correlated with plant insect pollinator dependence and/or phylogenetic relatedness. We hypothesized that if pollen nutritional content was affected by pollinator attraction, it should be different (e.g., higher) in highly pollinator-dependent plants, independent of phylogenetic relatedness. We found that crude protein and the protein-to-lipid ratio in pollen strongly correlated with phylogeny. Moreover, pollen protein content was higher in plants depending mostly or exclusively on insect pollination. Pollen nutritional quality thus correlated with both phylogenetic relatedness and pollinator dependency, indicating that, besides producing pollen with sufficient nutrients for reproduction, the nutrient profile of zoophilous plants may have been shaped by their pollinators' nutritional needs
LISA technology and instrumentation
This article reviews the present status of the technology and instrumentation
for the joint ESA/NASA gravitational wave detector LISA. It briefly describes
the measurement principle and the mission architecture including the resulting
sensitivity before focussing on a description of the main payload items, such
as the interferomtric measurement system, comprising the optical system with
the optical bench and the telescope, the laser system, and the phase
measurement system; and the disturbance reduction system with the inertial
sensor, the charge control system, and the micropropulsion system. The article
touches upon the requirements for the different subsystems that need to be
fulfilled to obtain the overall sensitivity.Comment: 37 pages, 18 figures, submitted to CQ
Bumblebees under Stress
Bumblebees under stress: Negative effects of pesticides and heatwaves on colony growth and reproductio
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