Kenneth O. May, 1915–1977 : His early life to 1946

Kenneth Ownsworth May graduated from the University of California at Berkeley in 1936 with highest honors in mathematics. The following year he received his Masters degree and became a fellow of the Institute of Current World Affairs, and during the next two years he traveled to England, Europe, and Russia. On his return to the United States he became active in the Communist Party, the consequences of which would plague him for years. He joined the United States Army in 1942, serving with distinction, and after the war returned to Berkeley, where he obtained his Ph.D. in 1946. He immediately accepted an assistant professorship at Carleton College in Northfield, Minnesota, later moving to the University of Toronto.This part of May's biography focuses on the events up to his accepting a position at Carleton College. In this early phase his openness, his emphasis on good communications in the process of education, and his interest in practical procedures emerge which later set the background for his successful career as a leading historian of mathematics and the founding editor of Historia Mathematica.     

Gold-Catalyzed C−H Functionalization Polycondensation for the Synthesis of Aromatic Polymers

Homogeneous gold (Au) complexes have demonstrated tremendous utility in modern organic chemistry; however, their application for the synthesis of polymers remains rare. Herein, we demonstrate the first catalytic application of Au complexes toward the polycondensation of alkyne-containing comonomers and heteroarene nucleophiles. Polymerization occurs through successive intermolecular hydroarylation reactions to produce high molecular weight aromatic copolymers with 1,1-disubstituted alkene backbone linkages. Clear correlations between the rate and degree of polymerization (DP) were established based on catalyst structure and counterion pairing, thus enabling polymerization reactions that proceeded with remarkable efficiency, high reactivity, and exceptional DPs. The reactivity is broad in scope, enabling the copolymerization of highly functionalized aromatic and aliphatic monomers. These results highlight the untapped utility of Au catalysis in providing access to new macromolecular constructs.     

The synthesis of phosphonic acid and phosphate analogues of glycerol-3-phosphate and related metabolites

A convenient route is described for the preparation of the isosteric phosphonic acid analogue of glycerol-3-phosphate, 3,4-dihydroxybutyl-1-phosphonic acid, in both enantiomeric forms and the racemic modification, starting with readily available materials. The (S)-enantiomer, that of absolute configuration corresponding to that of sn-glycerol-3-phosphate, has been found to be a growth inhibitor of several bacteria at low concentration. The synthetic route described is of particular value as it facilitates the preparation of a series of phosphonic adds and phosphates of related structure, in their enantiomeric forms, which are also of interest for metabolic regulation. These include the 3,4-epoxybutyl-1-phosphonate and a phosphate analogue of glycerol-3-phosphate with the related homodiglyceride. Investigations are continuing in the evaluation of the biological activity of the materials synthesized. A method is also described for the synthesis of the carbon-14 labelled 3-carboxy-3-hydroxybutyl-1-phosphonic acid, an analogue of phosphoglyceric acid known to serve as a substitute for the natural material in several biochemical processes.     

The restricted isometry property for time–frequency structured random matrices

This paper establishes the restricted isometry property for a Gabor system generated by n ² time–frequency shifts of a random window function in n dimensions. The sth order restricted isometry constant of the associated n × n ² Gabor synthesis matrix is small provided that s ≤ c n ^2/3 / log² n. This bound provides a qualitative improvement over previous estimates, which achieve only quadratic scaling of the sparsity s with respect to n. The proof depends on an estimate for the expected supremum of a second-order chaos.     

Fragmentation of adenine and uracyl molecules through electron captures in collisions with ions

The time-of-flight mass spectrometry method is used to study processes occurring when 36-keV multiply charged Ar ions (Ar⁶⁺) capture electrons from adenine and uracyl molecules. Adenine and uracyl constitute one of two base pairs entering into the RNA composition. The fragmentation scheme of resulting molecular ions is derived by analyzing correlations between the detection times of all fragment ions. Fragmentation patterns for molecular ions resulting from molecule ionization by photons, electrons, protons, and multiply charged ions are compared.     

Calculation of thermoelastic stresses near the crystallization front for melt-grown single-crystal rods with a circular cross section

Approximate expressions for the thermoelectric stress tensor components in an isotropic crystal rod of a circular cross section, applicable in the entire crystal including the region near the crystallization front, are obtained. Using the resultant approximate formulas, the stress fields in leucosapphire single crystals are calculated for model temperature fields. It is shown that exactly near the crystallization front, thermoelastic stresses reach maximal values.     

Combination of two fat saturation pulses improves detectability of glucose signals in carbon-13 MR spectroscopy

In order to improve the fat suppression performance of in vivo (13)C-MRS operating at 3.0 Tesla, a phantom model study was conducted using a combination of two fat suppression techniques; a set of pulses for frequency (chemical shift) selective suppression (CHESS), and spatial saturation (SAT). By optimizing the slab thickness for SAT and the irradiation bandwidth for CHESS, the signals of the -(13)CH(3) peak at 49 ppm and the -(13)CH(2)- peak at 26 ppm simulating fat components were suppressed to 5% and 19%, respectively. Combination of these two fat suppression pulses achieved a 53% increase of the height ratio of the glucose C1β peak compared with the sum of all other peaks, indicating better sensitivity for glucose signal detection. This method will be applicable for in vivo (13)C-MRS by additional adjustment with the in vivo relaxation times of the metabolites.     

Sharp Recovery Bounds for Convex Demixing,with Applications

Demixing refers to the challenge of identifying two structured signals given only the sum of the two signals and prior information about their structures. Examples include the problem of separating a signal that is sparse with respect to one basis from a signal that is sparse with respect to a second basis, and the problem of decomposing an observed matrix into a low-rank matrix plus a sparse matrix. This paper describes and analyzes a framework, based on convex optimization, for solving these demixing problems, and many others. This work introduces a randomized signal model that ensures that the two structures are incoherent, i.e., generically oriented. For an observation from this model, this approach identifies a summary statistic that reflects the complexity of a particular signal. The difficulty of separating two structured, incoherent signals depends only on the total complexity of the two structures. Some applications include (1) demixing two signals that are sparse in mutually incoherent bases, (2) decoding spread-spectrum transmissions in the presence of impulsive errors, and (3) removing sparse corruptions from a low-rank matrix. In each case, the theoretical analysis of the convex demixing method closely matches its empirical behavior.