376,214 research outputs found

    The Sun, stellar-population models, and the age estimation of high-redshift galaxies

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    Given sufficiently deep optical spectroscopy, the age estimation of high-redshif t (z>1z > 1) galaxies has been claimed to be a relatively robust process (e.g. Dunlop et al. 1996) due to the fact that, for ages <5< 5Gyr, the near-ultraviolet light of a stellar population is expected to be dominated by `well-understood' main-sequence (MS) stars. Recently, however, the reliability of this process has been called into question by Yi et al (2000), who claim to have developed models in which the spectrum produced by the main sequence reddens much more rapidly than in the models of Jimenez et al (2000a), leading to much younger age estimates for the reddest known high-redshift ellipticals. In support of their revised age estimates, Yi et al cite the fact that their models can reproduce the spectrum of the Sun at an age of 5 Gyr, whereas the solar spectrum is not reproduced by the Jimenez et al models until ≃10\simeq 10 Gyr. Here we confirm this discrepancy, but point out that this is in fact a {\it strength} of the Jimenez et al models and indicative of some flaw in the models of Yi et al (which, in effect, imply that the Sun will turn into a red giant any minute now). We have also explored the models of Worthey (1994) (which are known to differ greatly from those of Jimenez et al in the treatment of post-MS evolution) and find that the main-sequence component of Worthey's models also cannot reproduce the solar spectrum until an age of 9-10 Gyr. We conclude that either the models of Yi et al are not as main-sequence dominated at 4-5 Gyr as claimed, or that the stellar evolutionary timescale in these models is in error by a factor possibly as high as two. (abridged)Comment: Submitted to MNRAS, final versio

    Expressions of Another Center: Borderlands Visual Theory & the Art of Luis Jimenez

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    An artist who constantly challenged various social and political boundaries, Jimenez and his art contribute to a growing discourse about U.S. sculpture and 21st century American art. By combining various methodologies such as formal analysis, visual analysis, and critical biography, I will underscore the significance of Luis Jimenez\u27s art in 21st century American art. Jimenez\u27s art functions autobiographically particular moment in his life affected his art in many ways. His time in Mexico City, New York, and Rome are a few pivotal moments that shifted the focus of his art and encouraged him to return to the Southwest where his controversial art was created. My methodological approach is based on a concept I call borderlands visual theory. This methodological practice will consist of a social history of art with close attention to content, context, and connoisseurship. An interdisciplinary method that will facilitate the research design of my project, borderlands visual theory explains the theories and methods of Jimenez\u27s contemporary artistic practices. Rooted in histories of oppression and suffering, borderlands visual theory emerges within a framework of purpose, resourcefulness, and an against the grain, anti-border mentality. Grounding my analysis of Jimenez within a larger discussion about American and Chicana/o art will underscore the effective methods Jimenez employed to reach a diverse audience. Jimenez\u27s artworks offer an innovative conceptualization of aesthetics and cultural identity and critically examine regional and national politics. He offers an understanding about American art that is hybrid, differential, and contingent, rather than pure or monolithic. By examining Jimenez\u27s artwork within the rubric of borderlands visual theory, I will offer a more fruitful discussion about his resourceful, innovative, and multidimensional practice that contemporary writings about him neglect. Differentiated by his style politics and motivated by his sociocultural interventions, Jimenez authored unique methods that engage with the issues of his time. My project will illuminate various moments of artistic intervention that situate Jimenez within a larger, and arguably a more appropriate, discussion about American art. Luis Jimenez was a titan in the art world his monumental sculptures and poignant lithographs reveal his commitment for a shared humanity as well as provide a platform for his social and artistic agendas. Jimenez created works of art that combined formal artistic practices with Chicana/o vernacular aesthetics. In addition, Jimenez\u27s incorporation of classical themes and remarkable attention to form situate his art in distinguished academic categories of sculpture and American art. His innovative use of fiberglass materials and archetypal themes position his unique perspective within formalized discussions in art history. The magnitude of Jimenez\u27s artwork has not been thoroughly documented because of his ability to cross over into the American art scene, this project will trace out the significant factors that enabled him to cross borders historically closed off to artists of color

    Combinatorial proofs of q-series identities

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    We provide combinatorial proofs of some of the q-series identities considered by Andrews, Jimenez-Urroz and Ono [q-series identities and values of certain LL-functions. Duke Math. J. 108 (2001), no. 3, 395--419].Comment: 14 pages. Submitted to Journal of Combinatorial Theory

    Anthony Jimenez

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    USA v. Jimenez

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    USDC for the District of New Jerse

    USA v. Jimenez

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    USDC for the District of New Jerse
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