Estimation of the solubility parameters of model plant surfaces and agrochemicals: a valuable tool for understanding plant surface interactions

Background Most aerial plant parts are covered with a hydrophobic lipid-rich cuticle, which is the interface between the plant organs and the surrounding environment. Plant surfaces may have a high degree of hydrophobicity because of the combined effects of surface chemistry and roughness. The physical and chemical complexity of the plant cuticle limits the development of models that explain its internal structure and interactions with surface-applied agrochemicals. In this article we introduce a thermodynamic method for estimating the solubilities of model plant surface constituents and relating them to the effects of agrochemicals. Results Following the van Krevelen and Hoftyzer method, we calculated the solubility parameters of three model plant species and eight compounds that differ in hydrophobicity and polarity. In addition, intact tissues were examined by scanning electron microscopy and the surface free energy, polarity, solubility parameter and work of adhesion of each were calculated from contact angle measurements of three liquids with different polarities. By comparing the affinities between plant surface constituents and agrochemicals derived from (a) theoretical calculations and (b) contact angle measurements we were able to distinguish the physical effect of surface roughness from the effect of the chemical nature of the epicuticular waxes. A solubility parameter model for plant surfaces is proposed on the basis of an increasing gradient from the cuticular surface towards the underlying cell wall. Conclusions The procedure enabled us to predict the interactions among agrochemicals, plant surfaces, and cuticular and cell wall components, and promises to be a useful tool for improving our understanding of biological surface interactions

Assessment of Skeletal Muscle Contractile Properties by Radial Displacement: The Case for Tensiomyography

Skeletal muscle operates as a near-constant volume system; as such muscle shortening during contraction is transversely linked to radial deformation. Therefore, to assess contractile properties of skeletal muscle, radial displacement can be evoked and measured. Mechanomyography measures muscle radial displacement and during the last 20 years, tensiomyography has become the most commonly used and widely reported technique among the various methodologies of mechanomyography. Tensiomyography has been demonstrated to reliably measure peak radial displacement during evoked muscle twitch, as well as muscle twitch speed. A number of parameters can be extracted from the tensiomyography displacement/time curve and the most commonly used and reliable appear to be peak radial displacement and contraction time. The latter has been described as a valid non-invasive means of characterising skeletal muscle, based on fibre-type composition. Over recent years, applications of tensiomyography measurement within sport and exercise have appeared, with applications relating to injury, recovery and performance. Within the present review, we evaluate the perceived strengths and weaknesses of tensiomyography with regard to its efficacy within applied sports medicine settings. We also highlight future tensiomyography areas that require further investigation. Therefore, the purpose of this review is to critically examine the existing evidence surrounding tensiomyography as a tool within the field of sports medicine

It only takes a few: On the Hardness of voting with a constant number of agents

Many hardness results in computational social choice make use of the fact that every directed graph may be induced by the pairwise majority relation. However, this fact requires that the number of voters is almost linear in the number of alternatives. It is therefore unclear whether existing hardness results remain intact when the number of voters is bounded, as is for example typically the case in search engine aggregation settings. In this paper, we provide sufficient conditions for majority graphs to be obtainable using a constant number of voters and leverage these conditions to show that winner determination for the Banks set, the tournament equilibrium set, and ranked pairs remains hard even when there is only a small constant number of voters

It only takes a few: On the Hardness of voting with a constant number of agents

Many hardness results in computational social choice make use of the fact that every directed graph may be induced by the pairwise majority relation. However, this fact requires that the number of voters is almost linear in the number of alternatives. It is therefore unclear whether existing hardness results remain intact when the number of voters is bounded, as is for example typically the case in search engine aggregation settings. In this paper, we provide sufficient conditions for majority graphs to be obtainable using a constant number of voters and leverage these conditions to show that winner determination for the Banks set, the tournament equilibrium set, and ranked pairs remains hard even when there is only a small constant number of voters

k-Majority digraphs and the hardness of voting with a constant number of voters

Many hardness results in computational social choice use the fact that every digraph may be induced as the pairwise majority relation of some preference profile. The standard construction requires a number of voters that is almost linear in the number of alternatives and it is unclear whether hardness holds when the number of voters is bounded. In this paper, we systematically study majority digraphs inducible by a constant number of voters. First, we characterize digraphs inducible by two or three voters, and give sufficient conditions for more voters. Second, we use SAT solvers to compute the minimum number of voters required to induce digraphs given by generated and real-world preference profiles. Finally, using our sufficient conditions, we show that several voting rules remain hard to evaluate for small constant numbers of voters. Kemeny's rule remains hard for 7 voters; previous methods could only prove this for constant even numbers of voters