Publications by authors named "J H Quastel"

We introduce a new disorder regime for directed polymers in dimension 1+1 by scaling the inverse temperature β with the length of the polymer n. We scale β(n)≔βn(-α) for α≥0. This scaling interpolates between the weak disorder (β=0) and strong disorder regimes (β>0).

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This lecture consists of a short appraisal of some of the main features that have characterized the growth of biochemistry during the course of the 20th century. It dwells on the early impacts of vitalism, the emergence and elucidation of the vitamins, the discovery of coenzymes, the concept of active centres of enzymes, the development of experimental techniques (including the use of isotopes), the genetic code, and on the development of molecular biology and closely allied fields of investigation. It concludes with a consideration of the influence of the study of membranes and of neurochemistry on current biochemical thought.

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This lecture consists of a short appraisal of some of the main features that have characterized the growth of biochemistry during the course of the 20th century. It dwells on the early impacts of vitalism, the emergence and elucidation of the vitamins, the discovery of coenzymes, the concept of active centres of enzymes, the development of experimental techniques (including the use of isotopes), the genetic code, and on the development of molecular biology and closely allied fields of investigation. It concludes with a consideration of the influence of the study of membranes and of neurochemistry on current biochemical thought.

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Calcium ions (10 microM) enhance the permeability of the hepatic inner mitochondrial membrane to acetyl-CoA (and CoA). This effect is suppressed by the absence of phosphate ions or by the presence of EGTA, La3+, or ruthenium red. Exposure of mitochondria to Ca2+ for short intervals of time (e.

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Labeled acetylcholine derived from labeled pyruvate in a synaptosomal preparation from rat brain, incubated with nicotinamide adenine dinucleotide as well as coenzyme A, is stimulated by calcium ions in the absence but not in the presence of Triton X-100. Whereas citrate is taken up by cholinergic synaptosomes because it suppresses the formation of acetylcholine from pyruvate, it is not itself converted into acetylcholine. The evidence suggests that there is a calcium-dependent transfer of mitochondrial acetyl coenzyme A into the cholinergic synaptoplasm, which is apparently devoid of the citrate cleavage enzyme, and is there converted into acetylcholine.

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