948 resultados para Lewis and Clark Expedition (1804-1806)


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Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Omega(GW)(f) = Omega(alpha)(f/f(ref))(alpha), we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of alpha = 0, we constrain the energy density of the stochastic background to be Omega(GW)(f) < 5.6 x 10(-6). For the 600-1000 Hz band, Omega(GW)(f) < 0.14(f/900 Hz)(3), a factor of 2.5 lower than the best previously reported upper limits. We find Omega(GW)(f) < 1.8 x 10(-4) using a spectral index of zero for 170-600 Hz and Omega(GW)(f) < 1.0(f/1300 Hz)(3) for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

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The Brazilian federal government Agency for Health Surveillance detected pesticide residues in fresh food available for consumers all over the country. The current study investigated the effects of a mixture of some of those pesticides (dichlorvos, dicofol, dieldrin, endosulfan, and permethrin) on the reproductive system of Sprague-Dawley (SD), Wistar (WT), and Lewis (LEW) rats. Female rats from each strain were randomized into three experimental groups and were fed a control diet or diets added with pesticides mixture at their respective no-observed-effect level (NOEL)/no-observed-adverse-effect level (NOAEL) (low dose) (mg/kg/d): dichlorvos (0.23), dicofol (0.5), dieldrin (0.025), endosulfan (0.7), permethrin (5), or lowest-observed-effect level (LOEL)/lowest-effect level (LEL)/ lowest-observed-adverse-effect level (LOAEL) (toxically effective dose) (mg/kg/d): dichlorvos (2.3), dicofol (2.1), dieldrin (0.05), endosulfan (3.8), and permethrin (25) as reported in the literature. Euthanasia was performed between wk 10 and 12, during the estrous stage. Decreased body weights gain (SD and WT) and increased liver weights (SD, WT, and LEW) were observed in each strain fed the pesticides mixture at the higher levels. At that dose level, rat strains also varied in their responses regarding the estrous cycle, hormonal levels, and number of developing ovarian follicles. The studied mixture of pesticides was found to interfere with the female reproductive system when individual pesticides were mixed above a certain level, indicating a threshold exists for each of the strains studied.

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In this paper we present the results of a coherent narrow-band search for continuous gravitational-wave signals from the Crab and Vela pulsars conducted on Virgo VSR4 data. In order to take into account a possible small mismatch between the gravitational-wave frequency and two times the star rotation frequency, inferred from measurement of the electromagnetic pulse rate, a range of 0.02 Hz around two times the star rotational frequency has been searched for both the pulsars. No evidence for a signal has been found and 95% confidence level upper limits have been computed assuming both that polarization parameters are completely unknown and that they are known with some uncertainty, as derived from x-ray observations of the pulsar wind torii. For Vela the upper limits are comparable to the spin-down limit, computed assuming that all the observed spin-down is due to the emission of gravitational waves. For Crab the upper limits are about a factor of 2 below the spin-down limit, and represent a significant improvement with respect to past analysis. This is the first time the spin-down limit is significantly overcome in a narrow-band search.

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The role played by H+ hydrido iodocarbonyl and H- hydrido carbonyl ruthenium catalysts in the different catalytic steps of hydroformylation and hydroesterification of olefins, and in the homologation of alcohols has been investigated. The H- hydrido carbonyl species are mainly involved in the activation of olefins and in the hydrogenation of the acyl intermediates to aldehydes and alcohols, whereas the H+ hydrido iodocarbonyl derivatives are involved in the activation of alcohols and other oxygenated substrates, and in their carbonylation to esters. The cooperation between the two species, possible under particular reaction conditions, results in an improvement of the selectivity towards homologation (carbonylation plus hydrogenation) products. Heterogeneous Lewis acid promoters, easily recyclable from the reaction mixture, have also been successfully used in the hydrocarbonylation of alcohols, resulting in an increase of the carbonylation and homologation products. A reaction pathway in agreement with the experimental results is discussed. © 1989.

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This article analyzes the main objectives of the scientific voyage to circumnavigate the earth, undertaken by the United States from 1838 to 1842. Charting was one of the most important of the scientific and strategic goals of the exploratory voyage. The initiative for the undertaking was the search for exact positioning on the high seas after the establishment of the longitude system, when nautical charts and maps from various countries were compared, and other, new ones were drawn. The United States participated in this international effort, leading to the creation of its own cartographic system.

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The deep-water molluscs collected during the expedition MD55 off SE Brazil have been gradually studied in some previous papers. The present one is focused on samples belonging to caenogastropod taxa Xenophoridae Troschel, 1852, Cypraeoidea Rafinesque, 1815, mitriforms and Terebridae Morch, 1852. Regarding the Xenophoridae, Onustus aquitanus n. sp. is a new species, collected off the littoral of Espirito Santo and Rio de Janeiro, Brazil, 430-637 m depth (continental slope). The main characters of the species include the small size (c. 20 mm), the proportionally wide shell, the white colour, the short peripheral flange, the oblique riblets weakly developed and a brown multispiral protoconch. This appears to be the smallest living species of the family, resembling in this aspect fossil species. In respect to the Cypraeoidea, the following results were obtained: family Cypraeidae Rafinesque, 1815: Erosaria acicularis (Gmelin, 1791) and Luria cinerea (Gmelin, 1791) had the deepest record, respectively 607-620 m and 295-940 m, although the samples were all dead, eroded shells. Family Lamellariidae d'Orbigny, 1841: a total of three lots were collected, provisionally identified as Lamellaria spp. as the samples consist of only vestigial shells; possibly each lot represents a different species. Family Pediculariidae Gray, 1853: a sample of Pedicularia tibia Simone, 2005 was found, expanding the range c. 1000 km southwards, from Ceara to Espirito Santo. Family Ovulidae Fleming, 1822: Pseudosimnia lacrima n. sp., collected off Espirito Santo, 607-620 m depth, is described here and is mainly characterised by its strong biconic outline, small size (c. 7 mm), and a thick peripheral callus. Family Triviidae Troschel, 1863: Cleotrivia antillarum (Schilder, 1922) is recorded for the first time as deep as 620 m, and its distribution expanded from Rio Grande do Norte to Espirito Santo; Dolichupis akangus n. sp. with rounded outline and c. 15 transverse ribs; D. pingius n. sp. with the outer lip expanded posteriorly and c. 10 ribs. In respect to the mitriform neogastropods, the following species are emphasised: family Costellariidae MacDonald, 1860: Vexillum sp., 607-620 m depth; Turricostellaria amphissa n. sp., 295 m depth; T. jukyry n. sp.; T. apyrahi n. sp., both 790-1575 m depth; T. ovir n. sp., 1200 m depth; Nodicostellaria crassa (Simone, 1995), 240-600 m depth, with extension northwards of the range up to Espirito Santo; Austromitra decresca n. sp., 60-105 m depth. Family Mitridae Swainson, 1829: Subcancilla joapyra n. sp., 295 m depth; S. cf. straminea (Adams, 1853), 607-620 m depth. Family Volutomitridae Gray, 1854: Microvoluta corona n. sp., 1500-1575 m depth. Family Mitromorphidae Casey, 1904: Mitromorpha sama n. sp., 607-940 m depth; M. mirim n. sp., 60105 m depth. Regarding the conoidean Terebridae, this paper is a complement of a previous study. It deals with a new species Terebra assu Simone n. sp., from the Abrolhos Bank, 295 m depth, characterised by its narrow outline, yellowish colour, weak sculpture on the last whorls, and a proportionally broad, paucispiral protoconch. A second finding of Terebra alagoensis Lima, Tenorio & Barros, 2007 expands the geographic range from Alagoas to north Espirito Santo. A discussion on the systematics of the "complex Terebra doellojuradoi" in South American coast is also provided, highlighting the improbability of synonymy between T. leptapsis Simone, 1999 and T doellojuradoi Carcelles, 1953. Differences in size, sculpture, spire angulation, aperture, and mainly in protoconch, indicate specific separations. The presently studied terebrids belong to the "complex Terebra doellojuradoi", which encompasses closely related, deep-water, small species, possessing a relatively high degree of endemicity.

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Dichloroindium hydride revealed to be a valid alternative to tributyltin hydride for radical reduction of organic (alkyl, aryl, acyl, solfonyl) azides. The new approach entails mild reaction conditions and provides high yields of the corresponding amines and amides, also showing high degrees of selectivity. The system dichloroindium hydride / azides can be utilised in fivemembered ring closures of g-azidonitriles, as a new source of aminyl radicals for the attractive synthesis of interesting amidine compounds in the absence of both toxic reagents and tedious purification procedures. Allylindium dichloride seems a good substitute for dichloroindium hydride for generation of indium centred radicals under photolytic conditions, since it allows allylation of electrophilic azides (e.g. phenylsulfonyl azide) and halogen or ester δ-substituted azides, the latter through a 1,5-H transfer rearrangement mechanism. Evidences of the radical nature of the reactions mechanism were provided by ESR spectroscopy, furthermore the same technique, allowed to discover that the reaction of azides with indium trichloride and other group XIII Lewis acids, in particular gallium trichloride, gives rise to strongly coloured, persistent paramagnetic species, whose structure is consistent with the radical cation of the head-to-tail dimer of the aniline corresponding to the starting azide.

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In 1938, a young folk music collector named Alan Lomax—destined to become one of the legendary folklorists of the 20th century recorded Michigan’s richly varied folk music traditions for the Archive of American Folk-Song at the Library of Congress. Michigan in the 1930s was experiencing a golden age of folksong collecting, as local folklorists mined the trove of ballads remembered by aging lumbermen and Great Lakes schoonermen. In addition to the ballads of these north woods singers, Lomax recorded a vibrant mix of ethnic music from Detroit to the western Upper Peninsula. The multimedia performance event Folksongs from Michigan-i-o combines live performance with historic images, color movie footage, and recorded sound from the Great Depression. Some of these materials haven’t been heard or seen by the general public for more than seven decades. The traveling exhibition Michigan Folksong Legacy: Grand Discoveries from the Great Depression brings Alan Lomax’s 1938 field trip to life through words, song lyrics, photographs, and sound recordings. Ten interpretive banners explore themes and each panel contains a QR code that links to related sound recordings from the Alan Lomax Collection at the American Folklife Center, Library of Congress.

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In 1938, a young folk music collector named Alan Lomax—destined to become one of the legendary folklorists of the 20th century recorded Michigan’s richly varied folk music traditions for the Archive of American Folk-Song at the Library of Congress. Michigan in the 1930s was experiencing a golden age of folksong collecting, as local folklorists mined the trove of ballads remembered by aging lumbermen and Great Lakes schoonermen. In addition to the ballads of these north woods singers, Lomax recorded a vibrant mix of ethnic music from Detroit to the western Upper Peninsula. The multimedia performance event Folksongs from Michigan-i-o combines live performance with historic images, color movie footage, and recorded sound from the Great Depression. Some of these materials haven’t been heard or seen by the general public for more than seven decades. The traveling exhibition Michigan Folksong Legacy: Grand Discoveries from the Great Depression brings Alan Lomax’s 1938 field trip to life through words, song lyrics, photographs, and sound recordings. Ten interpretive banners explore themes and each panel contains a QR code that links to related sound recordings from the Alan Lomax Collection at the American Folklife Center, Library of Congress.

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In 1938, a young folk music collector named Alan Lomax—destined to become one of the legendary folklorists of the 20th century recorded Michigan’s richly varied folk music traditions for the Archive of American Folk-Song at the Library of Congress. Michigan in the 1930s was experiencing a golden age of folksong collecting, as local folklorists mined the trove of ballads remembered by aging lumbermen and Great Lakes schoonermen. In addition to the ballads of these north woods singers, Lomax recorded a vibrant mix of ethnic music from Detroit to the western Upper Peninsula. The multimedia performance event Folksongs from Michigan-i-o combines live performance with historic images, color movie footage, and recorded sound from the Great Depression. Some of these materials haven’t been heard or seen by the general public for more than seven decades. The traveling exhibition Michigan Folksong Legacy: Grand Discoveries from the Great Depression brings Alan Lomax’s 1938 field trip to life through words, song lyrics, photographs, and sound recordings. Ten interpretive banners explore themes and each panel contains a QR code that links to related sound recordings from the Alan Lomax Collection at the American Folklife Center, Library of Congress.

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In the literature, some transition metal salts have been used as soft Lewis acids to activate alkynes toward nucleophilic attack. For example, Pt(II), Au(I) and Pd(II) catalysts can catalyze cycloisomerization reactions of alkynyl compounds to give a variety of cyclic products. In order to expand the scope of these reactions, in chapter 2 of this dissertation, several alkynyl epoxides were isomerized to cyclic allyl vinyl ethers using PtCl2 as the catalyst. Three of these allyl vinyl ethers were hydrolyzed to 2-hydroxymorpholine derivatives and two were converted to piperidine derivatives by thermal Claisen rearrangement. In order to find more benign and inexpensive catalysts for these types of reactions, in chapter 3 of this dissertation, BiCl3 was used to catalyze the isomerization of eight enynes to pyrrolidine derivatives. This reaction was normally catalyzed by expensive noble metal catalysts, such as Pd(II), Pt(II) and Au(I). All the cyclic products are valuable intermediates in the synthesis of bioactive molecules, these soft Lewis acid catalyzed cycloisomerization may find applications in the synthesis of bioactive molecules.

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Writing center scholarship and practice have approached how issues of identity influence communication but have not fully considered ways of making identity a key feature of writing center research or practice. This dissertation suggests a new way to view identity -- through an experience of "multimembership" or the consideration that each identity is constructed based on the numerous community memberships that make up that identity. Etienne Wenger (1998) proposes that a fully formed identity is ultimately impossible, but it is through the work of reconciling memberships that important individual and community transformations can occur. Since Wenger also argues that reconciliation "is the most significant challenge" for those moving into new communities of practice (or, "engage in a process of collective learning in a shared domain of human endeavor" (4)), yet this challenge often remains tacit, this dissertation examines and makes explicit how this important work is done at two different research sites - a university writing center (the Michigan Tech Multiliteracies Center) and at a multinational corporation (Kimberly-Clark Corporation). Drawing extensively on qualitative ethnographic methods including interview transcriptions, observations, and case studies, as well as work from scholars in writing center studies (Grimm, Denney, Severino), literacy studies (New London Group, Street, Gee), composition (Horner and Trimbur, Canagarajah, Lu), rhetoric (Crowley), and identity studies (Anzaldua, Pratt), I argue that, based on evidence from the two sites, writing centers need to educate tutors to not only take identity into consideration, but to also make individuals' reconciliation work more visible, as it will continue once students and tutors leave the university. Further, as my research at the Michigan Tech Multiliteracies Center and Kimberly-Clark will show, communities can (and should) change their practices in ways that account for reconciliation work as identity, communication, and learning are inextricably bound up with one another.