Viable entanglement detection of unknown mixed states in low dimensions

We explore procedures to detect entanglement of unknown mixed states, which can be experimentally viable. The heart of the method is a hierarchy of simple feasibility problems, which provides sufficient conditions to entanglement. Our numerical investigations indicate that the entanglement is detected with a cost which is much lower than full state tomography. The procedure is applicable to both free and bound entanglement, and involves only single copy measurements.Comment: 8 pages, 9 figures, 4 table

Longitudinal photocurrent spectroscopy of a single GaAs/AlGaAs v-groove quantum wire

Modulation-doped GaAs v-groove quantum wires (QWRs) have been fabricated with novel electrical contacts made to two-dimensional electron-gas (2DEG) reservoirs. Here, we present longitudinal photocurrent (photoconductivity/PC) spectroscopy measurements of a single QWR. We clearly observe conductance in the ground-state one-dimensional subbands; in addition, a highly temperature-dependent response is seen from other structures within the v-groove. The latter phenomenon is attributed to the effects of structural topography and localization on carrier relaxation. The results of power-dependent PC measurements suggest that the QWR behaves as a series of weakly interacting localized states, at low temperatures

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

Densidade populacional e peso médio de perfilhos de Panicum spp. em resposta a doses de fósforo e calcário na fase de estabelecimento.

O objetivo do estudo foi avaliar a densidade populacional e o peso médio de perfilhos de genótipos de Panicum spp. em resposta a doses de fósforo (P) e calagem. O delineamento experimental adotado foi inteiramente ao acaso com três repetições em parcelas subdivididas. Os tratamentos experimentais foram três doses de P (0, 60 e 400 kg/ha de P2O5) alocados nas parcelas e seis genótipos de P. maximum (Mombaça, Massai, PM32, PM34, PM39 e PM40), alocados nas subparcelas. Para o estudo do fator calagem a área foi dividida em metades iguais que receberam calcário equivalente a 35% e 50% de saturação por bases (V%). No 60º dia após o plantio foi avaliada a densidade populacional de perfilhos e o seu peso médio individual. A densidade populacional de perfilhos nas parcelas de V50 foi de 580 perfilhos/m2, enquanto que nas parcelas de V35, a densidade foi de 561 perfilhos/m2. A densidade populacional de perfilhos respondeu positivamente ao aumento das doses de P, independente de genótipo. Para a V35, os genótipos com ponto de máxima resposta mais baixo foram o acesso PM32 e o capim Massai, 77 e 86 kg/ha P2O5, respectivamente. Quanto ao peso médio de perfilhos, o ponto de máxima resposta para os acessos PM32 e PM34 na V35 foi de 273 e 272 kg/ha P2O5, respectivamente. De modo preliminar, o acesso PM32 apresentou máximo potencial de resposta com doses mais baixas de P, tanto para densidade populacional como para peso médio de perfilhos

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

Metallicity in the Galactic Center: The Arches cluster

We present a quantitative spectral analysis of five very massive stars in the Arches cluster, located near the Galactic center, to determine stellar parameters, stellar wind properties and, most importantly, metallicity content. The analysis uses a new technique, presented here for the first time, and uses line-blanketed NLTE wind/atmosphere models fit to high-resolution near-infrared spectra of late-type nitrogen-rich Wolf-Rayet stars and OfI+ stars in the cluster. It relies on the fact that massive stars reach a maximum nitrogen abundance that is related to initial metallicity when they are in the WNL phase. We determine the present-day nitrogen abundance of the WNL stars in the Arches cluster to be 1.6% (mass fraction) and constrain the stellar metallicity in the cluster to be solar. This result is invariant to assumptions about the mass-luminosity relationship, the mass-loss rates, and rotation speeds. In addition, from this analysis, we find the age of the Arches cluster to be 2-2.5Myr, assuming coeval formation

Abundance Gradients and the Formation of the Milky Way

In this paper we adopt a chemical evolution model, which is an improved version of the Chiappini, Matteucci and Gratton (1997) model, assuming two main accretion episodes for the formation of the Galaxy. The present model takes into account in more detail than previously the halo density distribution and explores the effects of a threshold density in the star formation process, during both the halo and disk phases. In the comparison between model predictions and available data, we have focused our attention on abundance gradients as well as gas, stellar and star formation rate distributions along the disk. We suggest that the mechanism for the formation of the halo leaves detectable imprints on the chemical properties of the outer regions of the disk, whereas the evolution of the halo and the inner disk are almost completely disentangled. This is due to the fact that the halo and disk densities are comparable at large Galactocentric distances and therefore the gas lost from the halo can substantially contribute to building up the outer disk. We also show that the existence of a threshold density for the star formation rate, both in the halo and disk phase, is necessary to reproduce the majority of observational data in the solar vicinity and in the whole disk. Moreover, we predict that the abundance gradients along the Galactic disk must have increased with time and that the average [alpha/Fe] ratio in stars (halo plus disk) slightly decrease going from 4 to 10 Kpcs from the Galactic center. We also show that the same ratios increase substantially towards the outermost disk regions and the expected scatter in the stellar ages decreases, because the outermost regions are dominated by halo stars.Comment: 41 pages (including the figures), To be published in Ap

Myxobolus sp. (Myxozoa) in the circulating blood of Colossoma macropomum (Osteichthyes, Characidae).

Myxosporea parasitize many organs in fresh and saltwater fish. Species of the genus Myxobolus parasitizing the gills and other organs of the tambaqui Colossoma macropomum have been described. In the present study, blood smears were made from juvenile tambaqui and were stained with May Grunwald-Giemsa-Wright in order to identify myxozoan parasites. Out of a total of 36 fish examined, one specimen (2.7%) that was reared in a cage presented spores that were identified as M. colossomatis, whereas fish kept in 250 L tanks showed prevalence of 5.5%. This is the first report of M. colossomatis in the blood of farmed tambaqui in the Amazon region. These results indicate that myxozoan parasites should also be investigated in fish blood smears. Some myxosporean species may cause diseases in fish, and these species need to be identified so that adequate preventive sanitary control can be instituted