The Development of an Integrated Communications Demand Model for the British Telecommunications Business

This paper describes aspects of a project in which a computer model (I.C.D.M.) of the longer-term trends in demand for telecommunications media in the U.K. was developed and implemented. The work was undertaken by Cambridge University Engineering Department for the Long Range and Strategic Studies Division of British Telecom. The paper concentrates on the processes of developing and implementing the model as an aid in the formulation of robust investment and marketing strategies for British Telecom in the face of a rapidly changing technological environment and emergent competition. The value of the integrative and dynamic characteristics of the I.C.D.M. in this context is emphasized, and the role of a user-friendly colour graphics interface in encouraging managerial acceptance of the new tool is noted.     

N-Amination of pyrrole and indole heterocycles with monochloramine (NH2Cl)

A survey of several electrophilic ammonia reagents for the N-amination of indole- and pyrrole-containing heterocycles revealed that monochloramine (NH(2)Cl) is an excellent reagent for this transformation. Pyrroles and indoles containing a variety of substitution were aminated on nitrogen with isolated yields ranging from 45% to 97%.     

Time-resolved flash spectroscopic investigations of the reactions of singlet arylhalocarbenes

The results of time-resolved laser flash spectrometric studies of singlet arylhalocarbenes are reviewed. In particular, the absolute rate constants for reactions of phenylchlorocarbene and related carbenes with alkenes are summarized and systematized. The experiments described provide the basis for a detailed examination of carbenic reactivity-selectivity principles. The results of studies on the influence of temperature on the absolute rate constants for carbene reactions are consistent with the existence of transient carbene/alkene intermediates.     

Dynamics of 1,3‐Dipolar Cycloaddition Reactions of Diazonium Betaines to Acetylene and Ethylene: Bending Vibrations Facilitate Reaction

Getting the bends : The dynamics of 1,3‐dipolar cycloaddition reactions have been explored by decomposing transition vector, quasi‐classical trajectories, and single trajectories. Dipole bending (see picture) makes the largest contribution to the TS distortion energy and constitutes the major part of transition‐state distortion energy in the favored concerted pathway.

     

Asymmetric synthesis of bicyclopropane derivatives

Both syn-and anti-bicyclopropane derivatives have been prepared with good relative and absolute stereocontrol using reagent controlled asymmetric cyclopropanation reactions. Double Simmons-Smith cyclopropanation of 2,4-dien-1-ols stereoselectively gave the corresponding anti-bicyclopropane derivatives.     

13C CIDNP derived from a 1,4-biradical generated in a norrish type II photolysis

NorRIsh type II photolysis of 1-benzoyl-1-methylcyclopentane, labeled with ¹³C in the carbonyl position, produces emissive CIDNP in the cyclization product. The polarization is consistent with the formation of a 1,4-biradical with a singlet ground state. By comparing this result with those for other biradicals, inferences are drawn about possible factors governing the singlet—triplet splittings of biradicals.     

An Algorithm for Generating Individualized Treatment Decision Trees and Random Forests

With new treatments and novel technology available, precision medicine has become a key topic in the new era of healthcare. Traditional statistical methods for precision medicine focus on subgroup discovery through identifying interactions between a few markers and treatment regimes. However, given the large scale and high dimensionality of modern datasets, it is difficult to detect the interactions between treatment and high-dimensional covariates. Recently, novel approaches have emerged that seek to directly estimate individualized treatment rules (ITR) via maximizing the expected clinical reward by using, for example, support vector machines (SVM) or decision trees. The latter enjoys great popularity in clinical practice due to its interpretability. In this article, we propose a new reward function and a novel decision tree algorithm to directly maximize rewards. We further improve a single tree decision rule by an ensemble decision tree algorithm, ITR random forests. Our final decision rule is an average over single decision trees and it is a soft probability rather than a hard choice. Depending on how strong the treatment recommendation is, physicians can make decisions based on our model along with their own judgment and experience. Performance of ITR forest and tree methods is assessed through simulations along with applications to a randomized controlled trial (RCT) of 1385 patients with diabetes and an EMR cohort of 5177 patients with diabetes. ITR forest and tree methods are implemented using statistical software R (https://github.com/kdoub5ha/ITR.Forest). Supplementary materials for this article are available online.     

Dynamics of carbene cycloadditions

Quasiclassical trajectory calculations using quantum mechanical energies and forces generated by the Venus and Gaussian programs provide for the first time a detailed dynamical picture of singlet carbene, CCl(2) and CF(2), cycloadditions to alkenes on the B3LYP/6-31G* surface. For CF(2), B3LYP/6-31G* with exact exchange reduced to 12% HF was also employed to better mimic the high accuracy surface. The range of geometries sampled in reactive trajectories and the timing of bond formation were explored. All trajectories follow the nonlinear approach proposed by Moore and Hoffmann. The reaction of CCl(2) with ethylene is a dynamically concerted reaction, with an average time gap between formation of the two bonds of 50 fs. The reaction of CF(2) with ethylene is dynamically complex with biexponential decay of the diradical species formed from the first bond formation. A general quantitative dynamical classification of cycloaddition mechanisms is proposed, based on the timing of bond formation.