A modest proposal: an approach to making the internal R system extensible

The R computing environment has become an important part of the statistical community and fostered the development of over a thousand add-on packages, many representing state-of-the-art research in statistical methodology. Although it is relatively easy to develop functionality on top of the system, it is very difficult for developers to directly extend the core system itself—the language, the interpreter and the internal data structures. Yet the ability to easily introduce new core, first-class data structures into the system that are customized and efficient is becoming essential in this era of large, complex data sets and innovative algorithms and data structures. While the community that might use such a facility to introduce new data types may be small, it is potentially very talented and important, and may lead to significant innovations that allow us to continue to leverage R for the next 5 years or more in rich new ways. I describe some of the difficulties that people encounter in extending the system and suggest that an object-oriented architecture for the internal implementation of R (or any system) would make such low-level internals extensible by package developers and not just the core development team. This would promote potentially rich experimentation that would allow us and others to approach new styles of computation in R, while simultaneously maintaining the existing important community which provides so much value-added to the R environment. Specifically, transforming the R implementation from a representation-specific architecture to a C++ abstract/virtual interface-based architecture may be the least disruptive approach to the continued evolution of R, and would bring many advantages and some technical challenges. Such an approach involves many technical details and potential degradations in performance. Due to the length of the this paper, I do not explore these issues in great detail but introduce the basic concepts. I do, however, refer to some technical aspects that are best understood with some knowledge of the implementation of R at the level of using the .Call () interface in R.     

Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes with Arylamines

A mixture of (3)AuCl [3 = P(t-Bu)(2)o-biphenyl] and AgOTf catalyzes the intermolecular hydroamination of monosubstituted and 1,1- and 1,3-disubstituted allenes with primary and secondary arylamines.     

Polycatenar, bent-core pyridines and their discotic complexes with silver(I)

New, bent-core, polycatenar pyridine mesogens are described. Binding to silver(I) leads to complexes properly described as discotic.     

Thioketene

Recent high-resolution FTIR studies of thioketene-H₂,-HD, and -D₂ have improved the precision with which a number of fundamental vibrations are determined and enabled accurate sets of rotation and distortion constants to be determined. These have been used, in conjunction with recent results for ketene, to determine the harmonic potential function for thioketene and the zero-point average molecular structure. A marked change in the methylene group geometry between thioketene and ketene is observed, such that a considerable increase in the CH bond length and concomitant decrease in the HCH angle occurs on sulfur substitution.     

A Note on Exact Moment Computation for Normal Lead Times in the Two-Supplier Case

In the stochastic lead time inventory model with two suppliers and different normal lead times, the mean and variance of the lead-time demand distribution are traditionally computed using numerical integration. Tables are made available to help practitioners determine the minimum size of replenishments when orders to the suppliers are placed at the same time. This paper presents closed-form solutions to evaluate the required quantities of interest and tries to correct some mistakes in the existing tables. The expressions given here may also provide insight into the choice of sole versus dual suppliers.     

Building the Additive Utility Functions for CAD-UFRJ Evaluation Staff Criteria

This paper presents an application of the UTA method for building utility functions for the evaluation criteria defined by the Staff Evaluation Commission (CAD) of the Rio de Janeiro Federal University (UFRJ). Every year, the CAD-UFRJ gives the staff evaluation results for each Postgraduate Engineering Programme. However, the method used to generate the staff evaluation is assumed unknown. Trying to find the CAD-UFRJ preference structure, the evaluation results supplied by CAD-UFRJ are used to apply the UTA method. Some additional information obtained from the CAD-UFRJ data is incorporated in the optimal solutions analysis.     

Solid phase synthesis of 5-aminopyrazoles and derivatives

The development of a novel solid phase synthesis of some 5-aminopyrazoles and derivatives is described. Reaction of hydrazines with solid supported β-keto-nitrile (1) affords 5-aminopyrazoles (2) the amino group of which is readily acylated or sulphonylated. Generation of the solid supported β-keto-nitrile (1) is non trivial and represents a key step in the overall synthesis.     

Rate enhancement of PFP sulfonate ester aminolysis by chloride salts in organic and aqueous media

We report here, a method of accelerating the rate of aminolysis of PFP sulfonates to yield sulfonamides using tetrabutylammonium salts. We have previously explored the utility of employing PFP sulfonates in the formation of sulfonamides; however we demonstrate here the advantages of combining the existing methodology with a revised protocol which allows the diversity within both the sulfonate ester and the amine to be extended.     

Cooperative Lewis Pairs Based on Late Transition Metals: Activation of Small Molecules by Platinum(0) and B(C6F5)3

A Lewis basic platinum(0)–CO complex supported by a diphosphine ligand and B(C₆F₅)₃ act cooperatively, in a manner reminiscent of a frustrated Lewis pair, to activate small molecules such as hydrogen, CO₂, and ethene. This cooperative Lewis pair facilitates the coupling of CO and ethene in a new way.