Denisiuk-type reflection holography display with sillenite crystals for imaging and interferometry of small objects

A novel setup for imaging and interferometry through reflection holography with Bi12TiPO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. (C) 2007 Elsevier B.V. All rights reserved.

The use of shallow seismic reflection technique in near surface exploration of urban sites: An evaluation in the city of SãO Paulo, Brazil

In order to evaluate the use of shallow seismic technique to delineate geological and geotechnical features up to 40 meters depth in noisy urban areas covered with asphalt pavement, five survey lines were conducted in the metropolitan area of São Paulo City. The data were acquired using a 24-bit, 24-channel seismograph, 30 and 100 Hz geophones and a sledgehammer-plate system as seismic source. Seismic reflection data were recorded using a CMP (common mid point) acquisition method. The processing routine consisted of: prestack band-pass filtering (90-250 Hz); automatic gain control (AGC); muting (digital zeroin) of dead/noisy traces, ground roll, air-wave and refracted-wave; CMP sorting; velocity analyses; normal move-out corrections; residual static corrections; f-k filtering; CMP stacking. The near surface is geologically characterized by unconsolidated fill materials and Quaternary sediments with organic material overlying Tertiary sediments with the water table 2 to 5 m below the surface. The basement is composed of granite and gneiss. Reflections were observed from 40 milliseconds to 65 ms two-way traveltime and were related to the silt clay layer and fine sand layer contact of the Tertiary sediments and to the weathered basement. The CMP seismic-reflection technique has been shown to be useful for mapping the sedimentary layers and the bedrock of the São Paulo sedimentary basin for the purposes of shallow investigations related to engineering problems. In spite of the strong cultural noise observed in these urban areas and problems with planting geophones we verified that, with the proper equipment, field parameters and particularly great care in data collection and processing, we can overcome the adverse field conditions and to image reflections from layers as shallow as 20 meters.

Representações do feminino em Dom Casmurro e The Turn of the Screw

Pós-graduação em Letras - FCLAS

Para além do que se vê: das transexualidades às singularidades na busca pela alteração corporal

Pós-graduação em Psicologia - FCLAS

The invisible blackness of Harryette Mullen's poetry: writing, miscegenation and what remais to be seen

Este ensaio aborda a poética de Harryette Mullen, poetisa afro-americana cuja obra questiona os limites que moldam as expectativas pela inteligibilidade acessível na literatura afro-americana. Os poemas de Mullen exploram as bordas da inteligibilidade, avançando para além das expectativas por uma forma visível/ Rev. Let., São Paulo, v.52, n.1, p.101-120, jan./jun. 2012. 119 inteligível de linguagem que abarcaria a experiência da negritude. Argumenta-se que a escrita na poesia de Mullen funciona como um processo de miscigenação ao jogar com a ilegibilidade da negritude, para além de uma linha visível de distinção entre o que é ou que deveria ser considerado como parte apropriada da negritude, o que possibilita novas formas de reflexão sobre a poesia como um instrumento politicamente significativo para se repensar o papel da poetisa e do poeta negros no espaço da diáspora negra.

The Invisible Blackness of Harryette Mullen's Poetry: Writing, Miscegenation, and What Remains to Be Seen

This essay addresses the poetics of Harryette Mullen, an awarded African-American female poet whose work questions the boundaries that shape the expectations for accessible intelligibility in African-American literature. Mullen’s poems skirt the edges of intelligibility by going beyond the expectations for a visible/intelligible form of language that would embrace the experience of blackness. I argue that writing in Mullen’s poetry works as process of miscegenation by playing on the illegibility of blackness, beyond a visible line of distinction between what is or should be considered part of blackness itself, which engages new forms of reflection on poetry as a politically meaningful tool for rethinking the role of the black (female) poet within the black diaspora.

The symbology of the sea in Lygia Bojunga Nunes's work: a reflection on utopian and dystopian framing

The ambivalent image of the sea is recurrent in Bojunga Nunes’s work. It receives a lot of symbolic meanings in her production, being sometimes a positive and sometimes a negative element. Thus, the sea is used in a utopic way, as a place for pleasure and leisure, and in a dystopic way, as scenery of a rite of passage, which includes the pain and suffering, part of the rite of passage that characterizes the bildungsromans. So, if in some texts the sea assumes a utopic character, being a place of snuggle, security, the ideal to reach, in others it is represented as dystopic, a place of distress, asphyxia and death. In this text we will study the hypothesis that, even in its dark symbolic meaning, in the author’s work the sea is an element of reflection and revelation. Thereby, it assumes metaphorically a sense of magnification of the reader’s expectative, being an element of emancipation. The objective of this text is to present a reflection on the sea’s symbolism on the mentioned texts and its importance for the reader’s formation.

Black Paul: a soul music no Brasil nos anos 1970

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Compact setup for reflection holography with Bi12TiO 20 crystals

A novel optical setup for imaging through reflection holography with Bi12TiO20 (BTO) sillenite photorefractive crystals is proposed. Aiming a compact, robust and simple optical setup the lensless Denisiuk arrangement was chosen, using a He-Ne red laser as light source. In this setup the holographic medium is placed between the light source and the object. The beam impinging the crystal front face is the reference one, while the light scattered by the surface is the object beam in a holographic recording by diffusion. In order to allow the readout of the diffracted wave only and to keep the setup simplicity a polarizing beam splitter cube (PBS) was positioned at the BTO input. The reference beam is s-polarized (polarization direction perpendicular to the table top) and the crystal. 〈001〉-axis is rotated by an angle γ with respect to the input polarization in order to make the transmitted object beam and the diffracted beam to have orthogonal polarizations. While the transmitted wave is reflected by the PBS at a right angle, the diffracted wave carrying the holographic reconstruction of the object passes through the PBS, being collected by a positive lens in order to form the holographic image at a CCD camera. The holographic recording with the grating vector is parallel to the 〈100〉-axis. An expression for the diffracted wave intensity as a function of γ was derived, and this relation was experimentally investigated. © 2008 American Institute of Physics.