4 resultados para Collapsed objects and Supernovae

em Repositório Científico da Universidade de Évora - Portugal


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This paper uses the example of the British Guiana Court at the Colonial and Indian Exhibition of 1886 as a case study to demonstrate how British Guiana (now Guyana) was represented in Britain at the time, by cross-referencing different materials (e.g. objects, correspondence, reports, and newspapers from that period). This exhibition also shows which raw materials from the British Guiana were of interest to Britain and the involvement of Royal Botanic Gardens, Kew in this matter. Nevertheless, the exhibition not only displayed objects and commodities, such as the case of sugar, but also displayed people. Here, particular attention is paid to the Amerindians who were portrayed as living ethnological exhibits at the exhibition. This paper aims to understand how British Guiana was seen and administered by its mother country and also how Everard im Thurn (1852-1932), the explorer, sought to manoeuvre that representation, as well as his relation with RBG, Kew. Taking into consideration that this colony was a neglected area of the British Empire, even in im Thurn’s time, this exhibition was an opportunity not only to display the empire but also for advertising the potential of the neglected colony and to ensure that it would not be forgotten.

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In archaeometry, the advantages of a combined use of Raman spectroscopy and X-ray fluorescence spectroscopy are extensively discussed for applications such as the analysis of paintings, manuscripts, pottery, etc. Here, we demonstrate for the first time the advantage of using both techniques for analysing glyptics. These engraved gemstones or glass materials were originally used as stamps, to identify the owner, for instance on letters, but also on wine vessels. For this research, a set of 64 glyptics (42 Roman glass specimens and 22 modern ones), belonging to the collection of the museum ‘Quinta das Cruzes’ in Funchal (Madeira, Portugal), was analysed with portable Raman spectroscopy and handheld X-ray fluorescence (hXRF). These techniques were also used to confirm the gemological identification of these precious objects and can give extra information about the glass composition. Raman spectroscopy identifies the molecular composition as well as on the crystalline phases present. On the other hand, hXRF results show that the antique Roman glass samples are characterised with low Pb and Sn levels and that the modern specimens can be discriminated in two groups: lead-based and non-lead-based ones.

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The present work was done on two ambrotypes and two tintypes. It aimed evaluate their chemical and physical characteristics, especially their degradation patterns. Moreover, to understand the materials used for their production and cross-check analytical and historical information about the production processes. To do so multi-analytical, non-destructive methods were applied. Technical photography highlighted the surface morphology of the objects and showed the distribution of the protective coatings on their surfaces through UV radiation, which were very different between the four pieces. OM allowed for a detailed observation of the surfaces along with the selection of areas of interest to be analysed with SEM-EDS. SEM-EDS was the technique used most extensively and the one that provided the most insightful results: it allowed to observe the morphology of the image forming particles and the differences between highlights, dark areas and the interfaces between them. Also, elemental point analysis and elemental maps were used to identify the image forming particles as silver and to detect the presence of compounds related to the production, particularly gold used to highlight jewellery, iron as the red pigment and traces of the compounds used in the photographic process containing Ag, I, Na and S . Also, some degradation compounds were analysed containing Ag, Cu, S and Cl. With μ-FT-IR the presence of collodion was confirmed and the source of the protective varnishes was identified, particularly mastic and shellac, in either mixtures of the two or only one. μ-Raman detected the presence of metallic silver and silver chloride on the objects and identified one of the red pigments as Mars red. Finally, μ-XRD showed the presence of metallic silver and silver iodide on both ambrotypes and tintypes and hematite, magnetite and wuestite on the tintypes; RESUMO: O presente estudo foi desenvolvido sobre dois ambrótipos e dois ferrótipos. O propósito consiste em estudar as suas características químicas e físicas, dando particular ênfase aos padrões de degradação. Também é pretendido compreender os materiais usados na sua produção e relacionar esta informação analítca com dados históricos de manuais técnicos contemporâneos à produção dos objectos. Para tal foram utilizadas técnicas multi-analíticas e não destrutivas. O uso da fotografia técnica permitiu uma observação da morfologia das superficies dos objectos e da distribuição das camadas de verniz através da radiação UV, muito diferente entre os quatro. A microscopia óptica proporcionou uma observação detalhada das superfícies assim como a selecção de pontos de interesse para serem analisados com SEM-EDS. SEM-EDS foi a técnica usada mais extensivamente e a que proporcionou os resultados mais detalhados: observação da morofologia das partículas formadoras da imagem e as diferenças entre zonas de altas luzes, baixas luzes e as interfaces entre elas. A análise elemental e os mapas elementares foram usados para detectar prata nas partículas formadoras da imagem e a presença de compostos relacionados com a produção, em particular ouro utilizado para realçar joalharia, ferro no pigmento vermelho e vestígios de compostos utilizados no processo fotográfico incluindo Ag, I, Na e S. Do mesmo modo, alguns compostos de degradação foram analisados contendo Ag, Cu, S e Cl. Com μ-FT-IR a presença de colódio foi confirmada e identificada a origem dos vernizes, mástique e goma-laca, tanto em misturas dos dois como apenas um. Com μ-Raman foi detectada a presença de prata metálica e de cloreto de prata e identificado um dos pigmentos vermelhos como Mars red. Finalmente, μ-DRX revelou a presença de prata metálica e iodeto de prata tanto nos ambrótipos como nos ferrótipos e hematite, magnetite e wuestite nos ferrótipos.

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Com a presente investigação pretendeu-se validar a metodologia de análise retrospetiva de vídeos familiares e explorar potenciais sinais de risco precoce em crianças com SXF(N=6). Utilizando grelhas de observação de comportamentos, analisou-se a atenção social, a atenção partilhada, e o desenvolvimento sensório-motor, nas crianças com SXF, dos 0-30 meses. Validou-se a metodologia de análise de vídeos retrospetivos para a identificação de sinais de risco. Com base no estudo dos sinais de risco, sugere-se que as crianças com SXF têm preferência por estímulos não-sociais (e.g., fixação visual prolongada em objetos), têm dificuldades em dirigir a atenção para estímulos sociais (e.g., chamada e resposta ao nome) e défices na atenção partilhada, e demonstram uma interação prolongada e repetitiva com objetos e as expressões afetivas positivas. Verificou-se também que as crianças com SXF parecem conseguir discriminar entre estímulos sociais e não-sociais (e.g., vocalização para as pessoas) e apresentam estereotipias em todas as idades; Identifying early risk features in children with FXS through home movies Abstract: This research aims to validade the retrospective video analysis methodology of home movies and to explore potential early risk signs in children with FXS (N=6). Recurring to an observational grids of behaviors, social attention, joint attention, social attention and sensorymotor features were analysed, in children with FXS, at 0-30 months. Retrospective video analysis was validated for the identification of early risk signs. The study of early risk signs suggests that infants with FXS prefer non-social stimuli (e.g., visual fixation in objects), have difficulties directing attention toward social stimuli (e.g., name prompts) and impairments in joint attention, prolongued and repetitive interaction with objects, and have positive affective rating. Findings reveal that infants with FXS seem to be able to discriminate from social and non-social stimuli (e.g., vocalizing to people) and presente stereotypies through all ages.