Bs Physics at CDF and D0

Run II at the Tevatron has seen an explosion of results related to the Bs meson, ranging from tests of QCD models, to probes of electro-weak symmetry breaking, to direct searches for new physics effects. I will briefly summarize the CDF and D0 Bs-physics programs, describing the suitability of the detectors for doing this kind of physics, and pointing out how our knowledge of important quantities has improved through Run II measurements.Comment: added Fermilab-Conf number, corrected two misquoted theoretical result

The Suez crisis: a study in press performance

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Enzymatic N-Acetylation of Indolealkylamines by Brain Homogenates of the Honeybee, Apis Mellifera

Brain homogenates of the honeybee, Apis mellifera, have been found to possess enzymes capable of catalyzing the N-acetylation of tryptamine and 5-hydroxytryptamine with acetyl coenzyme A as the acetyl donor. The Km of the N-acetylation of tryptamine was 5. 0 x 10-7 M at iii pH 7. 0 and 33°C. Evidence was obtained that the indolealkylamines, tryptamine and 5-hydroxytryptamine, are not oxidized by monoamine oxidase (MAO) as is commonly considered to be a major catabolic route in vertebrate animals. Certain commonly used assays, reportedly specific for monoamine oxidase activity, will not distinguish between oxidation by MAO and N-acetylation of tryptamine and so should not be used to assay for MAO activity in insect tissues without careful identification of the products of the reaction. Implications of N-acetylation of indolealkylamines are discussed in relation to the neurotransmitter problem

A thousand words is worth a picture

In this response to Ribeiro and Lima’s paper on interactional expertise, we argue that, by not incorporating the insights of constructivist social science, their analysis goes backwards rather than advancing the debate. We show that much of the evidence they present does not lead to the conclusions they draw. We also critically examine the idea of physical contiguity, which forms a central part of Ribeiro and Lima’s position. We show that its meaning is ambiguous. We conclude by suggesting that more research on the nature and influence of physical contiguity would be interesting in its own right but that it would not bear on the notion of interactional expertise

Multiple mechanisms of spiral wave breakup in a model of cardiac electrical activity

It has become widely accepted that the most dangerous cardiac arrhythmias are due to re- entrant waves, i.e., electrical wave(s) that re-circulate repeatedly throughout the tissue at a higher frequency than the waves produced by the heart's natural pacemaker (sinoatrial node). However, the complicated structure of cardiac tissue, as well as the complex ionic currents in the cell, has made it extremely difficult to pinpoint the detailed mechanisms of these life-threatening reentrant arrhythmias. A simplified ionic model of the cardiac action potential (AP), which can be fitted to a wide variety of experimentally and numerically obtained mesoscopic characteristics of cardiac tissue such as AP shape and restitution of AP duration and conduction velocity, is used to explain many different mechanisms of spiral wave breakup which in principle can occur in cardiac tissue. Some, but not all, of these mechanisms have been observed before using other models; therefore, the purpose of this paper is to demonstrate them using just one framework model and to explain the different parameter regimes or physiological properties necessary for each mechanism (such as high or low excitability, corresponding to normal or ischemic tissue, spiral tip trajectory types, and tissue structures such as rotational anisotropy and periodic boundary conditions). Each mechanism is compared with data from other ionic models or experiments to illustrate that they are not model-specific phenomena. The fact that many different breakup mechanisms exist has important implications for antiarrhythmic drug design and for comparisons of fibrillation experiments using different species, electromechanical uncoupling drugs, and initiation protocols.Comment: 128 pages, 42 figures (29 color, 13 b&w

B Lifetimes and Mixing

The Tevatron experiments, CDF and D0, have produced a wealth of new B-physics results since the start of Run II in 2001. We've observed new B-hadrons, seen new effects, and increased many-fold the precision with which we know the properties of b-quark systems. In these proceedings, we will discuss two of the most fruitful areas in the Tevatron B-physics program: lifetimes and mixing. We'll examine the experimental issues driving these analyses, present a summary of the latest results, and discuss prospects for the future.Comment: Heavy Quarks and Leptons, Melbourne, 2008, references adde