Lambda Calculus in Core Aldwych

Core Aldwych is a simple model for concurrent computation, involving the concept of agents which communicate through shared variables. Each variable will have exactly one agent that can write to it, and its value can never be changed once written, but a value can contain further variables which are written to later. A key aspect is that the reader of a value may become the writer of variables in it. In this paper we show how this model can be used to encode lambda calculus. Individual function applications can be explicitly encoded as lazy or not, as required. We then show how this encoding can be extended to cover functions which manipulate mutable variables, but with the underlying Core Aldwych implementation still using only immutable variables. The ordering of function applications then becomes an issue, with Core Aldwych able to model either the enforcement of an ordering or the retention of indeterminate ordering, which allows parallel execution

Recursive computation of the invariant measure of a stochastic differential equation driven by a L\'evy process

We investigate some recursive procedures based on an exact or ``approximate'' Euler scheme with decreasing step in vue to computation of invariant measures of solutions to S.D.E. driven by a L\'evy process. Our results are valid for a large class of S.D.E. that can be governed by L\'evy processes with few moments or can have a weakly mean-reverting drift, and permit to find again the a.s. C.L.T for stable processes

Hydrophobic adsorption and covalent immobilization of Candida antarctica lipase B on mixed-function-grafted silica gel supports for continuous-flow biotransformations

Adsorption onto solid supports has proven to be an easy and effective way to improve the mechanical and catalytic properties of lipases. Covalent binding of lipases onto the support surface enhances the active lifetime of the immobilized biocatalysts. Our study indicates that mesoporous silica gels grafted with various functions are ideal supports for both adsorptive and covalent binding for lipase B from Candida antarctica (CaLB). Adsorption of CaLB on phenyl-functionalized silica gels improved in particular its specific activity, whereas adsorption on aminoalkyl-modified silica gels enabling covalent binding with the proper reagents resulted in only moderate specific activity. In addition, adsorption on silica gels modified by mixtures of phenyl- and aminoalkyl silanes significantly increased the productivity of CaLB. Furthermore, CaLB adsorbed onto a phenyl/aminoalkyl-modified surface and then treated with glutardialdehyde (GDA) as cross-linking agent provided a biocatalyst of enhanced durability. Adsorbed and cross-linked CaLB was resistant to detergent washing that would otherwise physically deactivate adsorbed CaLB preparations. The catalytic properties of our best immobilized CaLB variants, including temperature-dependent behavior were compared between 0 and 70 C with those of two commercial CaLB biocatalysts in the continuous-flow kinetic resolutions of racemic 1-phenylethanol rac-1a and 1-phenylethanamine rac-1b. © 2013 Elsevier Ltd

Process

The invention provides a process for preparing olefins from a mixed gaseous feed stream, wherein said mixed gaseous feed stream comprises three or more components selected from the group consisting of carbon dioxide, carbon monoxide, hydrogen, methanol and dimethyl ether, said process comprising contacting the mixed gaseous feed stream with a catalyst of formula (I): Μ(ΙΙ)χΑl11-χΡO4 (I), wherein M(II) is a divalent metal ion; and x = 0.002 to 0.5</p