2,370 research outputs found

    Searching for emission-line galaxies: The UCM survey

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    We are carrying out a long-term project with the main purposes of finding and analyzing low metallicity galaxies. A very small number of very low metallicity galaxies is known up to now. However these ojbects are particularly interesting since they are excellent candidates to 'young galaxies' in evolutionary sense as POX186 (Kunth, Maurogordato & Vigroux, 1988). Since the interstellar matter in these objects is only weakly contaminated by stellar evolution, their study could provide valuable information about the primordial helium abundance and therefore it could place constraints on the different Big-Bang models. The instrumental set up of our survey is an objective-prism used with the Schmidt telescope at Calar Alto Observatory. By using hypersensitized IIIaF emulsion and RG630 filter low resolution spectra in the H alpha region of objects in a wide field is obtained (Rego et al. 1989, Zamorano et al. 1990). Surveys carried out in the past two decades at optical blue wavelengths have also produced large samples of emission-line galaxies (ELGs), for example MacAlpine & Willians 1981 and reference therein, Wasilewski 1983, Salzer and MacAlpine 1988, or Smith et al. 1976. Relying primarily on objective-prism plates taken in the blue, these surveys have found over 3000 blue/emission-line galaxies so far. A significant number of star-forming galaxies are missed by optical surveys in the blue because of their low-excitation spectra (MacAlpine and Willians 1981, Markarian et al. 1981 and references therein) or their low metallicity (Kunth and Sargent, 1986)

    Construction of coherent states for physical algebraic systems

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    We construct a general state which is an eigenvector of the annihilation operator of the Generalized Heisenberg Algebra. We show for several systems, which are characterized by different energy spectra, that this general state satisfies the minimal set of conditions required to obtain Klauder's minimal coherent states.Comment: 15 pages, 3 figure

    Plantas uliginosas e aquaticas do Pantanal arenoso.

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    Com o objetivo de apoiar projetos de pesquisa sobre plantas forrageiras e componentes bioticos de habitats (jacare, peixes), iniciou-se em 1984 o levantamento de plantas aquaticas e uliginosas de lugares umidos no leque aluvial arenoso do rio Taquari, que abrange Nhecolandia e Paiaguas no Pantanal. A Nhecolandia caracteriza-se pelas lagoas (= "baias"), e Paiaguas, pelas vazantes, ou drenagem abertas. Ambas as sub-regioes tem campos estacionalmente palustres com plantas uliginosas e aquaticas. Algumas comunidades como "pirizal", "caetezal", "taboal", "camalotal", etc, tem nomes populares em funcao das plantas dominantes. No total foram listadas 157 especies, de 108 generos e 54 familias. As familias mais numerosas sao gramineae (37 especies) e Cyperaceae (19), seguidas de Leguminosae (10), Scrophulariceae (7), Eriocaulaceae (6), Alismataceae (5), Lentibulariaceae (5), Onagraceae (5) e Polygalaceae (5).bitstream/item/41130/1/PA06.pd

    Primary Intraosseous Squamous Cell Carcinoma of the Mandible: a Case with Atypical Imaging Features

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    Primary intraosseous squamous cell carcinoma is a rare malignant tumour that exclusively arises within the jaws. Its diagnosis requires an appropriate clinical, imaging and histological correlation. The exclusion of primary oral mucosa lesions and metastatic disease is mandatory. We report an atypical imaging appearance of this uncommon entity, characterized by new bone formation and periosteal reaction that resemble sarcomatous or malignant odontogenic tumours. A comprehensive discussion on the embryological principles of primary intraosseous squamous cell carcinoma is also provided.info:eu-repo/semantics/publishedVersio

    Monitoramento dos estádios fenológicos reprodutivos da cerejeira-do-mato.

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    Floração e frutificação da cerejeira-do-mato, em áreas fragmentadas da floresta ombrófila mista, no município de Colombo, PR.

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    bitstream/CNPF-2009-09/43225/1/circ-tec129.pd
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