Hertz

Abstract: The familiar buzz of flying mosquitoes is an important mating signal, with the fundamental frequency of the female's flight tone signaling her presence. In the yellow fever and dengue vector Aedes aegypti, both sexes interact acoustically by shifting their flight tones to match, resulting in a courtship duet. Matching is made not at the fundamental frequency of 400 hertz (female) or 600 hertz (male) but at a shared harmonic of 1200 hertz, which exceeds the previously known upper limit of hearing in mosquitoes. Physiological recordings from Johnston's organ (the mosquito's "ear") reveal sensitivity up to 2000 hertz, consistent with our observed courtship behavior. These findings revise widely accepted limits of acoustic behavior in mosquitoes.

Abstract: In the few pages of the doctoral dissertation on sin and expiation that he managed to complete before his death in World War I, Emile Durkheim's student Robert Hertz (1988) struggled with the methodological and conceptual problems of his project. Like Durkheim and Marcel Mauss, he wanted to delineate for comparative study a set of categories that were prevalent in European thought and of universal pretension. Were these categories in fact universal? Or were they the product of a particular level of social development? How could the two positions, both of which were more or less held by the Durkheimians, be reconciled? An evolutionary model, or rather orientation, offered a way out: it was, in fact, a cover story for what could not be reconciled on either conceptual or methodological grounds.' How could one study, for example, the nature of expiation in societies so different from 20th-century France that the very category was in question? How could a primordial notion of expiation, or sin, be identified? If it were identified, would this not suggest that there were, as Immanuel Kant had assumed, innate categories of the mind resistant to social, or contingent, determination? Or were there universal features of social organization that were reflected in such categories? What would these features be? The question of definition troubled Hertz. After a long discussion of sin and expiation in Christianity in the introduction to his thesis (Hertz 1988:5-27), he noted how difficult it would be to avoid the deep penetration of these Christian notions in any comparative study of religion. Hertz could offer only a weak methodological exit: To examine the facts without taking a position, a parti-pris, but with method. But can one? Hertz recognized, I believe, the impossibility of the Durkheimian project. His own procedure, though not without contradiction, was rather more complex than that of the Durkheimians: it was more psychological or at least more experiential.

Abstract: Abstract Three quarters of a century elapsed between Ampère's definition of electrodynamics and Einstein's reform of the concepts of space and time. The two events occurred in utterly different worlds: the French Academy of Sciences of the 1820s seems very remote from the Bern patent office of the early 1900s, and the forces between two electric currents quite foreign to the optical synchronization of clocks. Yet Ampère's electrodynamics and Einstein's relativity are firmly connected through an historical chain involving German extensions of Ampère's work, competition with British field conceptions, Dutch synthesis, and fin de siècle criticism of the aether-matter connection. Darrigol's book retraces this intriguing evolution, with a physicist's attention to conceptual and instrumental developments, and with an historian's awareness of their cultural and material embeddings. This book exploits a wide range of sources, and incorporates the many important insights of other scholars. Thorough accounts are given of crucial episodes such as Faraday's redefinition of charge and current, the genesis of Maxwell's field equations, or Hertz' experiments on fast electric oscillations. Thus emerges a vivid picture of the intellectual and instrumental variety of nineteenth century physics. The most influential investigators worked at the crossroads between different disciplines and traditions: they did not separate theory from experiment, they frequently drew on competing traditions, and their scientific interests extended beyond physics into chemistry, mathematics, physiology, and other areas. By bringing out these important features, this book offers a tightly connected and yet sharply contrasted view of early electrodynamics.

Abstract: Introduction: ways and means Part I: 1. First contact 2. The Shanghai stock market and the tributary state 3. Stock fever 4. City people, stock people Part II: 5. The big players 6. The dispersed players 7. 'Guojia': the rise and fall of a super-player 8. Conclusion: the trading crowd Afterwords Glossary of Chinese terms Bibliography Index.