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We present the 2–60 keV spectrum of the supernova remnant Cassiopeia A measured using the Proportional Counter Array and the High Energy X-ray Timing Experiment on the Rossi X-ray Timing Explorer satellite. In addition to the previously reported strong emission-line features produced by thermal plasmas, the broad-band spectrum has a high-energy " tail "(More)
Despite the fact that much has been written in recent years about the science of heredity under the Third Reich, there is as yet no satisfying analysis of two central questions: What, if anything, was peculiarly "Nazi" about human genetics under National Socialism? How, under whatever set of causes, did at least some of Germany's most well-known and leading(More)
The term 'mechanism' has been used in two quite different ways in the history of biology. Operative, or explanatory mechanism refers to the step-by-step description or explanation of how components in a system interact to yield a particular outcome (as in the 'mechanism of enzyme action' or the 'mechanism of synaptic transmission'). Philosophical Mechanism,(More)
Eugenics, the attempt to improve the human species socially through better breeding was a widespread and popular movement in the United States and Europe between 1910 and 1940. Eugenics was an attempt to use science (the newly discovered Mendelian laws of heredity) to solve social problems (crime, alcoholism, prostitution, rebelliousness), using trained(More)
The legacy of Mendel's pioneering studies of hybridization in the pea continues to influence the way we understand modern genetics. But what sort of picture did Mendel himself have of his work and its ultimate uses, and how does that picture compare with the collection of ideas and methodologies that was put forward in his name and later became known as(More)
Viktor Hamburger was a developmental biologist interested in the ontogenesis of hte vertebrate nervous system. A student of Hans Spemann at Freiburg in the 1920s, Hamburger picked up a holistic view of the embryo that precluded him from treating it in a reductionist way; at the same time, he was committed to a materialist and analytical approach that(More)