961 resultados para Hudson, Robert


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Digital Image

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Contains correspondence, printed material, and photographs relating to Jews in the medical profession, used as a basis for Kagan's several works on Jews in medicine, including the correspondence of members of the American Physicians Fellowship Committee of the Israel Medical Association; includes also correspondence relating to the Near East and the internationalization of Jerusalem, 1945-1954; and personal correspondence. Among the correspondents are Bernard M. Baruch and Christian A. Herter.

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We present two online algorithms for maintaining a topological order of a directed acyclic graph as arcs are added, and detecting a cycle when one is created. Our first algorithm takes O(m 1/2) amortized time per arc and our second algorithm takes O(n 2.5/m) amortized time per arc, where n is the number of vertices and m is the total number of arcs. For sparse graphs, our O(m 1/2) bound improves the best previous bound by a factor of logn and is tight to within a constant factor for a natural class of algorithms that includes all the existing ones. Our main insight is that the two-way search method of previous algorithms does not require an ordered search, but can be more general, allowing us to avoid the use of heaps (priority queues). Instead, the deterministic version of our algorithm uses (approximate) median-finding; the randomized version of our algorithm uses uniform random sampling. For dense graphs, our O(n 2.5/m) bound improves the best previously published bound by a factor of n 1/4 and a recent bound obtained independently of our work by a factor of logn. Our main insight is that graph search is wasteful when the graph is dense and can be avoided by searching the topological order space instead. Our algorithms extend to the maintenance of strong components, in the same asymptotic time bounds.

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Resumen: En ocasión de la autobiografía de Robert Spaemann aparecida en 2012, este trabajo examina la lectura que Spaemann hace de la teleología en la doctrina de Santo Tomás de Aquino, especialmente en su obra Natürliche Ziele (2005) que prosigue la versión de 1981. En la primera parte, se estudia la historia de la teleología en el pensamiento filosófico y científico expuesta en «Fines naturales». La finalidad intrínseca en la naturaleza de los seres es conocida con profundidad creciente gracias a Platón, Aristóteles, al estoicismo y a la tradición cristiana. Estos aportes se integran en una estructura teleológica unitaria en el Aquinate. Después acontece una «inversión» de la teleología centrada en la conservación del propio ser y una consideración de los fines como algo externo a la realidad. Con la teoría evolucionista surge la teleonomía que se limita a las reglas del dinamismo, suprimiendo el fin. Con todo, los científicos no logran eliminar los términos «con el fin de» o «para» en su lenguaje. Eso permite proceder a un redescubrimiento de los fines naturales. En la segunda parte, se ve cómo Tomás de Aquino lleva el conocimiento de la finalidad más allá de Aristóteles, porque ella remite a una inteligencia creadora. La teleología implica una teología, aunque no queda del todo claro si es la teología filosófica o la cristiana. Spaemann tiene un planteo ontológico de tipo persuasivo, pero en algunos momentos siente dificultad para superar en el plano teorético a quien se limita a una teleonomía.

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1 carta (manuscrita) ; 202x145mm.

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The benthic macrofauna of the New York Bight has been monitored extensively, primarily to determine trends over space and time in biological effects of waste inputs. In the present study, from 44 to 48 stations were sampled each summer from 1980-1985. Data from other Bight benthic studies are included to· extend the temporal coverage from 1979 to 1989. Numbers of species and amphipods per sample, taken as relatively sensitive indicators of environmental stress, showed consistent spatial patterns. Lowest values were found in the Christiaensen Basin and other inshore areas, and numbers increased toward the outermost shelf and Hudson Shelf Valley stations. There were statistically significant decreases in species and amphipods at most stations from 1980 to 1985. (Preliminary data from a more recent study suggest numbers of species increased again between 1986 and 1989.) Cluster analysis of 1980-85 data indicated several distinct assemblages-sewage sludge dumpsite, sludge accumulation area, inner Shelf Valley, outer Shelf Valley, outer shelf-with little change over time. The "enriched" and "highly altered" assemblages in the Basin appear similar to those reported since sampling began there in 1968. No consistently defaunated areas have been found in any sampling programs over the past 20 years. On a gross level, therefore, recent faunal responses to any environmental changes are not evident, but the more sensitive measures used, i.e. numbers of species and amphipods, do indicate widespread recent effects. Causes of the faunal changes are not obvious; some possibilities, including increasing effects of sewage sludge or other waste inputs, natural factors, and sampling artifacts, are discussed. (PDF file contains 54 pages.)

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Shortnose sturgeon (Acipenser brevirostrum), an endangered species, has experienced a several-fold increase in abundance in the Hudson River in recent decades. This population growth followed a substantial improvement in water quality during the 1970s to a large portion (c. 40%) of the species' summertime nursery area. Age structure and growth were investigated to evaluate the hypothesis that improvements in water quality stimulated population recovery through increased survival of young of the year juveniles. Specimens were captured using gill nets bi-monthly from November 2003 to November 2004 (n = 596). Annuli in fin spine sections were used to generate estimates of sturgeon age. Based upon a marginal increment analysis, annuli were determined to form at an annual rate. Age determinations yielded a catch composed of age 5-30 years for sizes 49-105cm Total Length (n = 554). Individual growth rate (von Bertalanffy coefficients: TL, = 1045mm, K = 0.07) for the population was similar to previous growth estimates within the Hudson River as well as proximal estuaries. Hindcast year-class strengths, based upon a recent stock assessment (Bain et al. 2000) and corrected for gill net mesh selectivity and cumulative mortality indicated high recruitments (28,000-43,000 yearlings)during 1986-1992, which were preceded and succeeded by c.5-year periods of lower recruitment (5,000-1 5,000 yearlings). Recruitment patterns were corroborated by trends in shortnose sturgeon bycatch from a Hudson utilities-sponsored monitoring program. Results indicated that Hudson River shortnose sturgeon abundance increased due to the formation of several strong year-classes occurring about five years subsequent to improved water quality in important nursery and forage habitats in the upper Hudson River estuary. (PDF contains 108 pages.)

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The biography of Charles Bradford Hudson that follows this preface had its seeds about 1965 when I (VGS) was casually examining the extensive files of original illustrations of fishes stored in the Division of Fishes, National Museum of Natural History, Smithsonian Institution. I happened upon the unpublished illustration of a rainbow trout by Hudson and was greatly impressed with its quality. The thought occurred to me then that the artist must have gone on to do more than just illustrate fishes. During the next 20 years I occasionally pawed through those files, which contained the work of numerous artists, who had worked from 1838 to the present. In 1985, I happened to discuss the files with my supervisor, who urged me to produce a museum exhibit of original fish illustrations. This I did, selecting 200 of the illustrations representing 21 artists, including, of course, Hudson. As part of the text for the exhibit, Drawn from the Sea, Art in the Service of Ichthyology, I prepared short biographies of each of the artists. The exhibit, with an available poster, was shown in the Museum for six months, and a reduced version was exhibited in U.S. and Canadian museums during the next 3 years.

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