Some generalizations relative to lithium aluminum hydride reactions

Zusammenfassung Unter den gewöhnlichen Reaktionsbedingungen bleiben-O-{ie356-1}-O- und -S-{ie356-2}-O-Gruppen durch LiAlH₄ unverändert, während -{ie356-3}-{ie356-4}-O- und möglicherweise auch-{ie356-5}-{ie356-6}-S-Gruppen an der C-O- bzw. C-S-Bindung gespalten werden. Diese Verallgemeinerungen, die sich auf aliphatische und aromatische Verbindungen, Zucker und Steroide, anwenden lassen, werden zur Bestätigung kürzlich aufgestellter Steroid- und Alkaloidformeln herangezogen. Es wird ein Reaktionsmechanismus vorgeschlagen.

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Contribution No. 8 from the Yerkes Research Laboratory, E. I. du Pont de Nemours & Co., Inc., Buffalo 7, New York.     

Some observations on the effect of Ro 7-1051 on Trypanosoma cruzi,particularly in cell culture

Summary The drug Ro 7-1051 showed a deleterious effect on the intracellular and extracellular forms of Trypanosoma cruzi represented by nuclear pyknosis, fragmentation and lysis of parasites and by its reduced susceptibility to infection.Acknowledgments. The authors are deeply thankful to Roche Products for supplying the drug and for valuable information. The authors are also grateful to Prof. Nelson Villa for criticism and to Miss edna Bertin for technical assistance     

Relativity of motion: From Occam to Galileo

Early observations of the southern celestial sky were reported in many sixteenth-century books and compilations of voyages of discovery. Here we analyse these accounts in order to find out what was really seen and reported by the first navigators. Our analysis had resulted in new interpretations of the phenomena reported by Amerigo Vespucci and Andreas Corsali. Thus, a reassessment of the discovery of the Coalsack Nebula, the Magellanic Clouds, and the Southern Cross can be made. From a comparative review of the observations of the latter constellation as published between 1500 and 1600, we demonstrate that only questionable records found their way to contemporary compilations of voyages of discovery, and that as a result public knowledge about this constellation at the end of the sixteenth century was entirely unreliable. Another problem we discuss is that although the stars of the Southern Cross were the first to be discovered, and were observed again and again by many navigators, it was not until 1678 that their proper positions were found in stellar atlases and star catalogues accessible to astronomers. We explain how negligence of and subsequently confidence in Ptolemy's astronomy by, respectively, the early navigators and cartographers, were at the root of this amazingly long-lasting gap in the knowledge of the southern celestial sky.     

Galileo and the problem of infinity

During the period before the Greek revolution of 1821, and especially during the years between 1750 and 1821, there were two ways in which European scientific thought was propagated in Greece. The first is traditional. It comes from ancient Greece and, through Byzantium, reaches the period before the Greek revolution. It makes known the thought of Aristotle, Democrititus, and others on ‘natural philosophy’. The second way comes from Europe. The Greek scholars of the period before the Greek revolution, and especially at the end of the eighteenth century, tried to bring to and propagate in Greece the spirit ofthe European Enlightenment, They tried to make known to the Greek people the scientific achievements of Newton, Descartes, Lavoisier, and Laplace. Scientific knowledge is an important weapon against superstition, and Greek students had to learn about science to become free persons in an independent Greek state.     

Some histochemical observations on the cuticle of fasciola indica verma, 1953

Résumé Les essais histochimiques pour la présence des protéïnes, graisses, phénols et réticulation aromatique (aromatic cross linkage) et des liaisons -S-S ont été faits sur le cuticule deFasciola indica Verma, 1953, trematode se trouvant dans le foie du buffle indien. Des résultats positifs pour les protéïnes (le groupe glycol) et négatifs pour les graisses, phénols et réticulation aromatique et les liaisons -S-S ont été obtenus.     

Leonardo da Vinci's solution to the problem of the pinhole camera

The longstanding challenge of the pinhole camera for medieval theorists was explaining why luminous bodies cast onto a screen different images at different distances from the screen.I argue that this problem was first solved not by Francesco Maurolico, as David Lindberg concludes in his influential series of articles on the camera, but by Leonardo da Vinci. In studies in the Codex Atlanticus dating c. 1508–14, Leonardo explains the changes in screen patterns with distance by applying a key perspective principle to two kinds of projection pyramids that figure into pinhole camera imaging.In contrast, Maurolico's later conclusions about the pinhole camera are only partly correct. Maurolico gives a mistaken account of why pinhole images change with distance. He also introduces the erroneous notion that similar superimposed parts of the camera image actually fuse as the screen withdraws.     

Alhazen,Leonardo, and late-medieval speculation on the inversion of images in the eye

No one before Platter and Kepler proposed retinal reception of an inverted visual image. The dominant tradition in visual theory, especially that of Alhazen and his Western followers, subordinated the intra-ocular geometry of visual rays to the requirement for an upright image and to preconceptions about the precise nature of the visual spirit and its part in vision. Henry of Langenstein and an anonymous glossator in the late Middle Ages proposed alternatives to Alhazen, including the suggestion of double inversion of the image. Leonardo da Vinci was aware of both Alhazen's theory and Henry's contradiction, but perhaps not of the anonymous hypothesis of double inversion. Leonardo's visual ‘theory’ has more the character of a critique than of a theoretical alternative, and he did not transcend the medieval concept of visual spirit.     

Some ultrastructural observations of cotyledonary tissue and microbodies fromPisum sativum

Zusammenfassung Mikrokörperchen mit Einfachmenbranen wurden bei 4 Tage alten Kotyledonen vonPisum sativum studiert und für einen cytochemischen Katalase-Test elektronenmikroskopisch verwendet. Das granuläre Reaktionsprodukt aus dem 3,3-diamino-benzidin Test für Katalase wurde ausschliesslich in den Einfachmembranen der Mikrokörperchen gefunden.     

Galileo and the problem of concentric circles

In 1892, Eliakim Hastings Moore accepted the task of building a mathematics department at the University of Chicago. Working in close conjuction with the other original department members, Oskar Bolza and Heinrich Maschke, Moore established a stimulating mathematical environment not only at the University of Chicago, but also in the Midwest region and in the United States in general. In 1893, he helped organize an international congress of mathematicians. He followed this in 1896 with the organization of the Midwest Section of the New York City-based American Mathematical Society. He became the first editor-in-chief of the Society's Transactions in 1899, and rose to the presidency of the Society in 1901.