2,454 research outputs found
O ensaio na crítica literária brasileira contemporânea
Esta tese pretende compreender os motivos que fazem do ensaio a forma de escrita mais
frequente na crítica literária brasileira do século XXI, num momento em que a crítica
realiza uma revisão de sua atuação. Com esse intuito, os conceitos de dispositivo e
contradispositivo, de Michel Foucault, tornam-se ponto de partida para a reflexão, o que
permite reconhecer no ensaio a possibilidade de novos caminhos para a racionalidade no
mundo contemporâneo, junto à literatura. O estudo acompanha o percurso do ensaio,
que se desenvolve lado a lado com o processo de formação do pensamento crítico desde
Michel de Montaigne, passando pela forte tradição crítica do Romantismo alemão,
resgatada por Georg Lukács e Walter Benjamin, até encontrar, a partir da segunda
metade do século XX, em Theodor Adorno e Roland Barthes desdobramentos ainda
mais complexos para o ensaio crítico-filosófico. A partir dessas premissas, o trabalho de
análise vai ao encontro de autores que exploram as possibilidades do ensaio em suas
obras, tornando indissociáveis, em muitos momentos, texto literário e texto de crítica.
As reflexões se voltam para os estudos teóricos e críticos de literatura, com destaque
para os textos de Antonio Candido, Roberto Schwarz, Silviano Santiago, João Cezar de
Castro Rocha, Alberto Pucheu e Nuno Ramos, com o objetivo de trazer à tona as
contribuições do ensaio para os estudos literários no Brasil. Sobretudo no que se refere à
inserção dos recursos estéticos da linguagem aos procedimentos de análise crítica,
chegando a aproximar os extremos da constante flutuação entre a ordem objetiva e a
ordem subjetiva da escrita literária, realçando a presença autoral e o posicionamento
ético diante dos temas sobre os quais os autores arrolados nesta tese se propõem a
pensar
Sulfur, Chlorine, & Argon Abundances in Planetary Nebulae. I: Observations and Abundances in a Northern Sample
This paper is the first of a series specifically studying the abundances of
sulfur, chlorine, and argon in Type II planetary nebulae (PNe) in the Galactic
disk. Ratios of S/O, Cl/O, and Ar/O constitute important tests of differential
nucleosynthesis of these elements and serve as strict constraints on massive
star yield predictions. We present new ground-based optical spectra extending
from 3600-9600 Angstroms for a sample of 19 Type II northern PNe. This range
includes the strong near infrared lines of [S III] 9069,9532, which allows us
to test extensively their effectiveness as sulfur abundance indicators. We also
introduce a new, model-tested ionization correction factor for sulfur. For the
present sample, we find average values of S/O=1.2E-2(+/- 0.71E-2),
Cl/O=3.3E-4(+/- 1.6E-4), and Ar/O=5.0E-3(+/- 1.9E-3).Comment: 44 pages, 6 figures. Accepted for publication in the Astrophysical
Journa
Nature of the constant factor in the relation between radial breathing mode frequency and tube diameter for single-wall carbon nanotubes
Resonance Raman scattering is used to determine the radial breathing mode (RBM) frequency (ωRBM) dependence on tube diameter (dt) for single-wall carbon nanotubes (SWNTs). We establish experimentally the ωRBM=227.0/dt as the fundamental relation for pristine SWNTs. All the other RBM values found in the literature can be explained by an upshift in frequency due mostly to van der Waals interaction between SWNTs and environment
Resistência do tipo antibiose a ninfas de Tibraca limbativentris (Stal, 1860) (Heteroptera: Pentatomidae) em variedades de arroz.
O percevejo-do-colmo (Tibraca limbativentris Stal, 1860) é uma importante praga do arroz no Brasil. O uso de variedades resistentes a esse inseto é uma ferramenta importante para o seu controle. O experimento foi conduzido em casa de vegetação na Embrapa Arroz e Feijão. Foi avaliada resistência tipo antibiose em ninfas de T. limbativentris em 16 variedades de arroz em delineamento experimental de blocos casualizados em oito repetições. Os caracteres utilizados para detectar indícios de resistência do tipo antibiose foram: número de ninfas vivas, massa seca (mg)/ninfas, superfície corporal/mm2, índice de sobrevivência e desenvolvimento e dias de vida das ninfas. Realizaram-se três tipos de análises: a) considerando somente os dados obtidos nas repetições avaliadas aos 7, 13, 21 e 26 dias após a infestação; b) considerando somente os dados das quatro repetições avaliadas aos 35 dias após a infestação e c) considerando os dados obtidos conjuntamente nas oito repetições. Conclui-se que as variedades Arroz Comum e Desconhecido Branco, principalmente a primeira, evidenciam possuir características que lhes confere determinado grau de resistência do tipo antibiose a ninfas de T. limbativentris
Histomorfologia funcional do intestino do pirarucu, Arapaima gigas (Cuvier, 1829).
Este trabalho avaliou a histomorfologia do intestino de juvenis de pirarucu, visando elucidar a dinâmica de absorção e aproveitamento de nutrientes pela espécie e subsidiar futuras pesquisas abrangendo sua nutrição e saúde.Organizado por: Sílvio Ricardo Maurano; AQUACIÊNCIA 2012
Atividade inseticida in vitro do óleo de sementes de nim sobre Lutzomyia longipalpis (Diptera: Psychodidae).
The physical parameters, excitation and chemistry of the rim, jets and knots of the planetary nebula NGC 7009
We present long-slit optical spectra along the major axis of the planetary
nebula NGC 7009. These data allow us to discuss the physical, excitation and
chemical properties of all the morphological components of the nebula,
including its remarkable systems of knots and jets. The main results of this
analysis are the following: i) the electron temperature throughout the nebula
is remarkably constant, T_e[OIII] = 10200K; ii) the bright inner rim and inner
pair of knots have similar densities of N_e = 6000cm^{-3}, whereas a much lower
density of N_e = 1500cm^{-3} is derived for the outer knots as well as for the
jets; iii) all the regions (rim, inner knots, jets and outer knots) are mainly
radiatively excited; and iv) there are no clear abundance changes across the
nebula for He, O, Ne, or S. There is a marginal evidence for an overabundance
of nitrogen in the outer knots (ansae), but the inner ones (caps) and the rim
have similar N/H values that are at variance with previous results. Our data
are compared to the predictions of theoretical models, from which we conclude
that the knots at the head of the jets are not matter accumulated during the
jet expansion through the circumstellar medium, neither can their origin be
explained by the proposed HD or MHD interacting-wind models for the formation
of jets/ansae, since the densities as well as the main excitation mechanisms of
the knots, disagree with model predictions.Comment: Figure 1 was changed because features were misidentified in the
previous version. 17 pages including 5 figures and 3 tables. ApJ in press.
Also available at http://www.iac.es/galeria/denise
B Physics at the Tevatron: Run II and Beyond
This report provides a comprehensive overview of the prospects for B physics
at the Tevatron. The work was carried out during a series of workshops starting
in September 1999. There were four working groups: 1) CP Violation, 2) Rare and
Semileptonic Decays, 3) Mixing and Lifetimes, 4) Production, Fragmentation and
Spectroscopy. The report also includes introductory chapters on theoretical and
experimental tools emphasizing aspects of B physics specific to hadron
colliders, as well as overviews of the CDF, D0, and BTeV detectors, and a
Summary.Comment: 583 pages. Further information on the workshops, including
transparencies, can be found at the workshop's homepage:
http://www-theory.lbl.gov/Brun2/. The report is also available in 2-up
http://www-theory.lbl.gov/Brun2/report/report2.ps.gz or chapter-by-chapter
http://www-theory.lbl.gov/Brun2/report
The dynamical evolution of the circumstellar gas around low-and intermediate-mass stars I: the AGB
We have investigated the dynamical interaction of low- and-intermediate mass
stars (from 1 to 5 Msun) with their interstellar medium (ISM). In this first
paper, we examine the structures generated by the stellar winds during the
Asymptotic Giant Branch (AGB) phase, using a numerical code and the wind
history predicted by stellar evolution. The influence of the external ISM is
also taken into account. We find that the wind variations associated with the
thermal pulses lead to the formation of transient shells with an average
lifetime of 20,000 yr, and consequently do not remain recorded in the density
or velocity structure of the gas. The formation of shells that survive at the
end of the AGB occurs via two main processes: shocks between the shells formed
by two consecutive enhancements of the mass-loss or via continuous accumulation
of the material ejected by the star in the interaction region with the ISM. Our
models show that the mass of the circumstellar envelope increases appreciably
due to the ISM material swept up by the wind (up to 70 % for the 1 Msun stellar
model). We also point out the importance of the ISM on the deceleration and
compression of the external shells. According to our simulations, large regions
(up to 2.5 pc) of neutral gas surrounding the molecular envelopes of AGB stars
are expected. These large regions of gas are formed from the mass-loss
experienced by the star during the AGB evolution.Comment: 43 pages, 15 figures. Accepted for publication in the Astrophysical
Journa
Stellar Iron Abundances at the Galactic Center
We present measurements of [Fe/H] for six M supergiant stars and three giant
stars within 0.5 pc of the Galactic Center (GC) and one M supergiant star
within 30 pc of the GC. The results are based on high-resolution (lambda /
Delta lambda =40,000) K-band spectra, taken with CSHELL at the NASA Infrared
Telescope Facility.We determine the iron abundance by detailed abundance
analysis,performed with the spectral synthesis program MOOG.The mean [Fe/H] of
the GC stars is determined to be near solar,[Fe/H] = +0.12 0.22. Our
analysis is a differential analysis, as we have observed and applied the same
analysis technique to eleven cool, luminous stars in the solar neighborhood
with similar temperatures and luminosities as the GC stars. The mean [Fe/H] of
the solar neighborhood comparison stars, [Fe/H] = +0.03 0.16, is similar
to that of the GC stars. The width of the GC [Fe/H] distribution is found to be
narrower than the width of the [Fe/H] distribution of Baade's Window in the
bulge but consistent with the width of the [Fe/H] distribution of giant and
supergiant stars in the solar neighborhood.Comment: 41 pages, 9 figures, ApJ, in pres
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