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Publications

Publications by CTM

2013

EarGram: An Application for Interactive Exploration of Concatenative Sound Synthesis in Pure Data

Authors
Bernardes, G; Guedes, C; Pennycook, B;

Publication
FROM SOUNDS TO MUSIC AND EMOTIONS

Abstract
This paper describes the creative and technical processes behind earGram, an application created with Pure Data for real-time concatenative sound synthesis. The system encompasses four generative music strategies that automatically rearrange and explore a database of descriptor-analyzed sound snippets (corpus) by rules other than their original temporal order into musically coherent outputs. Of note are the system's machine-learning capabilities as well as its visualization strategies, which constitute a valuable aid for decision-making during performance by revealing musical patterns and temporal organizations of the corpus.

2013

Lightons: Phonons with light

Authors
Silva, NA; Carvalho, MI; Guerreiro, A;

Publication
8TH IBEROAMERICAN OPTICS MEETING AND 11TH LATIN AMERICAN MEETING ON OPTICS, LASERS, AND APPLICATIONS

Abstract
Spatial solitons are robust localized nonlinear waves that are able to propagate without significant changes to their structure. Most of the proposal of the application of solitons uses them to transmit and process information in optical fibers and optical circuits. In the later the solitons can be guided through different paths by presetting some soliton characteristics (such as the phase), and even using some solitons to control the path of other pulses. In this paper, we use these properties of optical spatial solitons in a cubic nonlinear media to have lightons: phonon-like oscillations of a chain of solitonic light pulses. Conceptually, this work aims to explore the dual nature of solitons as a particle-like wave, by considering the displacement wave of solitons in a 1-dimensional chain.

2013

Spatial soliton dynamics in cubic-quintic media

Authors
Silva, NA; Carvalho, MI; Guerreiro, A;

Publication
8TH IBEROAMERICAN OPTICS MEETING AND 11TH LATIN AMERICAN MEETING ON OPTICS, LASERS, AND APPLICATIONS

Abstract
In this paper we address soliton-soliton interactions in a nonlinear cubic-quintic optic media, using for that purpose numerical methods and high performance graphics processor unit (GPU) computing. We describe an implementation of GPU-based computational simulations of the generalized Nonlinear Schrodinger Equation, obtaining simulations more than 40 times faster relative to CPU-based simulations, especially in the multidimensional case. We focus our attention in the study of soliton collisions and scattering phenomena that, offering the possibility of steering light with light, open a path towards future optical devices.

2013

The characteristic time of glucose diffusion measured for muscle tissue at optical clearing

Authors
Oliveira, LM; Carvalho, MI; Nogueira, EM; Tuchin, VV;

Publication
LASER PHYSICS

Abstract
The study of agent diffusion in biological tissues is very important to understand and characterize the optical clearing effects and mechanisms involved: tissue dehydration and refractive index matching. From measurements made to study the optical clearing, it is obvious that light scattering is reduced and that the optical properties of the tissue are controlled in the process. On the other hand, optical measurements do not allow direct determination of the diffusion properties of the agent in the tissue and some calculations are necessary to estimate those properties. This fact is imposed by the occurrence of two fluxes at optical clearing: water typically directed out of and agent directed into the tissue. When the water content in the immersion solution is approximately the same as the free water content of the tissue, a balance is established for water and the agent flux dominates. To prove this concept experimentally, we have measured the collimated transmittance of skeletal muscle samples under treatment with aqueous solutions containing different concentrations of glucose. After estimating the mean diffusion time values for each of the treatments we have represented those values as a function of glucose concentration in solution. Such a representation presents a maximum diffusion time for a water content in solution equal to the tissue free water content. Such a maximum represents the real diffusion time of glucose in the muscle and with this value we could calculate the corresponding diffusion coefficient.

2013

Comparison between optical measurements made from natural and frozen samples at optical clearing

Authors
Oliveira, L; Carvalho, MI; Nogueira, E; Tuchin, VV;

Publication
SARATOV FALL MEETING 2012: OPTICAL TECHNOLOGIES IN BIOPHYSICS AND MEDICINE XIV; AND LASER PHYSICS AND PHOTONICS XIV

Abstract
To determine the differences between the optical clearing effects created by ethylene glycol in fresh and frozen samples, we have performed several measurements from samples in both conditions. Fresh samples were used after animal sacrifice and frozen samples were kept at -20 degrees C for 72 hours. The different measurements performed with samples from both cases were total transmittance, collimated transmittance, total reflectance and specular reflectance. Considering, for instance, collimated transmittance measurements, we have verified that the spectra measured from both samples before adding the solution present different levels of collimated transmittance. The time-dependence evolution of the collimated transmittance spectrum is similar between both cases of samples, but since they present different levels of "natural" transmittance, the optical clearing effect is observed at different levels if we compare between fresh and frozen samples.

2013

Continuous wave supercontinuum generation pumped in the normal group velocity dispersion regime on a highly nonlinear fiber

Authors
Facao, M; Carvalho, MI; Fernandes, GM; Rocha, AM; Pinto, AN;

Publication
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS

Abstract
We have obtained spectral broadening by pumping a nonmicrostructured highly nonlinear fiber with a continuous wave signal from a Raman fiber laser. The experiment was simulated using a generalized Schrodinger equation containing the actual Raman response of the fiber as calculated from the experimental Raman gain. A different input-noise model, that reproduces well the power spectral density of the laser, was used and compared with others previously proposed. (C) 2013 Optical Society of America

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