20 research outputs found

    Die unvollendete Sonnenuhr von der Agora der Italiker auf Delos

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    Only one case of an unfinished ancient sundial can be found in the scientific literature. Found on the Greek island of Delos, it was first reported in 1938, although the sundial was then later considered lost. In our campaign of October 2012, we rediscovered the sundial. Using new and elaborate techniques, we created a 3D model of the sundial, which has enabled us to answer questions concerning its construction principles and the manufacturing processes used. Our first evaluation has revealed that, initially, its creators had intended to construct a cut conical sundial. Its discovery next to a workshop suggests that the sundial was left there in its unfinished state on the destruction of the island’s main town

    Longitude

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    This study traces the development of the concept of geographical longitude: from the ear- liest known Mesopotamian evidence of geographical concepts through its incorporation into mathematical astronomy and to its transmission to ancient Greek philosophy and scholarship. We show that there is a tight connection between the observation of lunar eclipses and the development of a quantitative representation of terrestrial longitudes. It was not until Ptolemy that geographical longitude was systematically quantified through angular differences. It is demonstrated that the ancient scholars failed in their attempts to determine geographical longitude by astronomical means, and that even certain Syriac texts which specify how to determine longitude using a planispheric astrolabe were unable to resolve this scientific challenge

    NR4A1-mediated apoptosis suppresses lymphomagenesis and is associated with a favorable cancer-specific survival in patients with aggressive B-cell lymphomas.

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    NR4A1 (Nur77) and NR4A3 (Nor-1) function as tumor suppressor genes as demonstrated by the rapid development of acute myeloid leukemia in the NR4A1 and NR4A3 knockout mouse. The aim of our study was to investigate NR4A1 and NR4A3 expression and function in lymphoid malignancies. We found a vastly reduced expression of NR4A1 and NR4A3 in chronic lymphocytic B-cell leukemia (71%), in follicular lymphoma (FL, 70%), and in diffuse large B-cell lymphoma (DLBCL, 74%). In aggressive lymphomas (DLBCL and FL grade 3), low NR4A1 expression was significantly associated with a non-germinal center B-cell subtype and with poor overall survival. To investigate the function of NR4A1 in lymphomas, we overexpressed NR4A1 in several lymphoma cell lines. Overexpression of NR4A1 led to a higher proportion of lymphoma cells undergoing apoptosis. To test the tumor suppressor function of NR4A1 in vivo, the stable lentiviral-transduced SuDHL4 lymphoma cell line harboring an inducible NR4A1 construct was further investigated in xenografts. Induction of NR4A1 abrogated tumor growth in the NSG mice, in contrast to vector controls, which formed massive tumors. Our data suggest that NR4A1 has proapoptotic functions in aggressive lymphoma cells and define NR4A1 as a novel gene with tumor suppressor properties involved in lymphomagenesis
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