Inf-convolution of G-expectations

In this paper we will discuss the optimal risk transfer problems when risk measures are generated by G-expectations, and we present the relationship between inf-convolution of G-expectations and the inf-convolution of drivers G.Comment: 23 page

On the monotone stability approach to BSDEs with jumps: Extensions, concrete criteria and examples

We show a concise extension of the monotone stability approach to backward stochastic differential equations (BSDEs) that are jointly driven by a Brownian motion and a random measure for jumps, which could be of infinite activity with a non-deterministic and time inhomogeneous compensator. The BSDE generator function can be non convex and needs not to satisfy global Lipschitz conditions in the jump integrand. We contribute concrete criteria, that are easy to verify, for results on existence and uniqueness of bounded solutions to BSDEs with jumps, and on comparison and a-priori $L^{\infty}$-bounds. Several examples and counter examples are discussed to shed light on the scope and applicability of different assumptions, and we provide an overview of major applications in finance and optimal control.Comment: 28 pages. Added DOI https://link.springer.com/chapter/10.1007%2F978-3-030-22285-7_1 for final publication, corrected typo (missing gamma) in example 4.1

Representation of the penalty term of dynamic concave utilities

In this paper we will provide a representation of the penalty term of general dynamic concave utilities (hence of dynamic convex risk measures) by applying the theory of g-expectations.Comment: An updated version is published in Finance & Stochastics. The final publication is available at http://www.springerlink.co

Water relations of the grape berry and aquaporins

Berry water content during development and at harvest is a crucial parameter of the vintage quality by directly impacting the concentration of sugars and flavour compounds. In the last decade, there has been considerable progress in understanding how berry water relations are involved in the ripening process as a result of exploring and integrating developmental changes in berry hydraulic conductivity, mineral nutrient loading, phloem unloading, xylem development, functionality of xylem vessels, cell vitality, cell water relations, gene expression and the molecular biology of aquaporins (water channels). In this chapter, we review the most recent advances in our understanding of the berry water influx and efflux during development and their consequences on cell turgor and apoplast solute concentrations, taking account of the changes in cell vitality observed late in ripening in some varieties. The role of aquaporins in the regulation of berry water relations is also presented, with a particular emphasis on the varietal differences observed in aquaporin functioning. Finally, the impact of water status of the parent vine on berry ripening is discussed. From this review, it appears that the varietal differences observed at different regulatory levels of berry water status represent a great opportunity to gain a better understanding of the ripening process.S. D. Tyerman, M. M. Chaves and F. Barrie

Plasma membrane intrinsic proteins from maize cluster in two sequence subgroups with differential aquaporin activity

The transport of water through membranes is regulated in part by aquaporins or water channel proteins. These proteins are members of the larger family of major intrinsic proteins (MIPs). Plant aquaporins are categorized as either tonoplast intrinsic proteins (TIPs) or plasma membrane intrinsic proteins (PIPs). Sequence analysis shows that PIPs form several subclasses. We report on the characterization of three maize (Zea mays) PIPs belonging to the PIP1 and PIP2 subfamilies (ZmPIP1a, ZmPIP1b, and ZmPIP2a). The ZmPIP2a clone has normal aquaporin activity in Xenopus laevis oocytes. ZmPIP1a and ZmPIP1b have no activity, and a review of the literature shows that most PIP1 proteins identified in other plants have no or very low activity in oocytes. Arabidopsis PIP1 proteins are the only exception. Control experiments show that this lack of activity of maize PIP1 proteins is not caused by their failure to arrive at the plasma membrane of the oocytes. ZmPIP1b also does not appear to facilitate the transport of any of the small solutes tried (glycerol, choline, ethanol, urea, and amino acids). These results are discussed in relationship to the function and regulation of the PIP family of aquaporins

Desiccation and osmotic stress increase the abundance of mRNA of the tonoplast aquaporin BobTIP26-1 in cauliflower cells.

Changes in vacuolar structure and the expression at the RNA level of a tonoplast aquaporin (BobTIP26-1) were examined in cauliflower (Brassicaoleracea L. var. botrytis) under water-stress conditions. Gradual drying out of slices of cauliflower floret tissue caused its collapse, with a shrinkage in tissue and cell volumes and an apparent vesiculation of the central vacuole, whereas osmotic stress resulted in plasmolysis with a collapse of the cytoplasm and the central vacuole within. Osmotic stress caused a rapid and substantial increase in BobTIP26 mRNA in slices of floret tissue. Exposure of tissue slices to a regime of desiccation showed a slower but equally large rise in BobTIP26 mRNA followed by a rapid decline upon rehydration. In situ hybridization showed that BobTIP26-2 mRNA is expressed most highly in meristematic and expanding cells of the cauliflower florets and that desiccation strongly increased the expression in those cells and in differentiated cells near the xylem vessels. These data indicate that under water-deficit conditions, expression of the tonoplast aquaporin gene in cauliflower is subject to a precise regulation that can be correlated with important cytological changes in the cells