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Publications

Publications by CAP

2019

High performance solver of the multidimensional generalized nonlinear Schrodinger equation with coupled fields

Authors
Ferreira, TD; Silva, NA; Guerreiro, A;

Publication
FOURTH INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
We report on the development of numerical module for the HiLight simulation platform based on GPGPU supercomputing to solve a system of coupled fields governed by the Generalized Nonlinear Schrodinger Equation with local and/or nonlocal nonlinearities. This models plays an important role in describing a plethora of different phenomena in various areas of physics. In optics, this model was initially used to describe the propagation of light through local and/or nonlocal systems under the paraxial approximation, but more recently it has been extensively used as a support model to develop optical analogues. However, establishing the relation between the original system and the analogue, as well as, between their model and the actual experimental setup is not an easy task. First and foremost because in most cases the governing equations are nonintegrable, preventing from obtaining analytical solutions and hindering the optimization of the experiments. Alternatively, despite numerical methods not providing exact solutions, they allow to test different experimental scenarios and provide a better insight to what to expect in an actual experiment, while giving access to all the variables of the optical system being simulated. However, the numerical solution of a system of N-coupled Schrodinger fields in systems with two or three spatial dimensions requires massive computation resources, and must employ advanced supercomputing and parallelization techniques, such as GPGPU. This paper focuses on the numerical aspects behind this challenge, describing the structure of our simulation module, its performance and the tests performed.

2019

HILIGHT: A NEW SIMULATION PLATFORM FOR ADVANCED PHOTONICS

Authors
Guerreiro, A; Silva, NA; Costa, J; Gomes, M; Alves, R; Ferreira, TD; Madureira, IS; Pereira, AAM; Almeida, AL;

Publication
FOURTH INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
We report on the development of HiLight, a new multiphysics simulation platform for advanced photonics with interactive modules dedicated to the study of the propagation of light in multitude of spatially structured optical media, including nonlocal and nonlinear media, optical lattices with atomic gases and plasmas, among others.

2019

A Simple Spectral Interrogation System for Optical Fiber Sensors

Authors
Santos,; Jorge,; Almeida,; Coelho,;

Publication
Proceedings

Abstract
Optical fiber sensors (OFS) based on long-period fiber gratings (LPFG) or on surface plasmon resonance (SPR) represent attractive solutions for detection systems in remote areas. An interrogation system consisting on wavelength modulation of fiber coupled distributed feedback (DFB) lasers was implemented and tested. The system uses a single photodetector to individually acquire the intensity of each DFB laser modulated by the OFS and the real transmission spectrum is reconstructed through curve fitting. Testing was accomplished by measuring the spectral features of an LPFG when changing the surrounding refractive index and errors lower than 1.8 nm in the 1530 to 1570 nm wavelength region were obtained.

2019

Evaluation of food labelling usefulness for consumers

Authors
Moreira, MJ; Garcia Diez, J; de Almeida, JMMM; Saraiva, C;

Publication
INTERNATIONAL JOURNAL OF CONSUMER STUDIES

Abstract
Food labelling is a means of communication between food business operators and consumers, representing an important factor in consumer purchasing decisions. The enforcement of the new food labelling policy is aimed to improve food safety and public health through the mandatory indication of information and nutritional values. To understand the usefulness of the information provided for consumers, a survey was carried out to assess the efficacy of the information presented in food labelling. Principal component analysis was performed to obtain a smaller number of uncorrelated factors regarding the usefulness of food labelling. Results showed consumers usually do not read food labels due to lack of time and excessive information. Additionally, food labelling was observed to be more useful for specific consumer groups, such as, athletes, consumers with health conditions or consumers concerned with a healthy lifestyle. The results of the present study highlight the need of information campaigns by public health authorities to show the importance and advantages of reading food labels as well as the development of essential information which should be quickly and clearly seen and understood by consumers.

2019

Catalytic Cyclization of Propargyl Bromoethers via Electrogenerated Nickel(I) Tetramethylcyclam in Ionic Liquids: Water Effects

Authors
Mendes, JP; Dunach, E; Esperanca, JMSS; Medeiros, MJ; Ribeiro, JF; Silva, MM; Olivero, S;

Publication
JOURNAL OF THE ELECTROCHEMICAL SOCIETY

Abstract
Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate the reductive intramolecular cyclization of propargyl bromoethers derivatives, catalyzed by electrogenerated (1,4,8,11-tetramethyl-1,4,8,11-tetraaza-cyclotetradecane) nickel(I), [Ni(tmc)](+), as the catalyst, in N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulfonyl) imide, [N-1 1 1 2(OH)][NTf2] and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, [C(2)mim][NTf2] in the absence and in the presence of water. The results show that the reaction leads to the formation of the expected heterocyclic compounds, in moderate to good yields. These compounds are important intermediates in the synthesis of natural products with possible biological activities. (C) 2019 The Electrochemical Society.

2019

A study of lead uptake and distribution in horns from lead-dosed goats using synchrotron radiation-induced micro X-ray fluorescence elemental imaging

Authors
Tehrani, MW; Huang, R; Guimaraes, D; Smieska, L; Woll, A; Parsons, PJ;

Publication
JOURNAL OF TRACE ELEMENTS IN MEDICINE AND BIOLOGY

Abstract
Objective: The principal goal of this study was to investigate the uptake and distribution of lead (Pb) in the horns of Pb-dosed goats, and to explore possible links to their historical Pb dosing records. Horn is a keratinized material that grows in discrete increments with the potential to preserve the historical record of past environmental exposures. While previous studies have leveraged this potential to examine environmental and biological phenomena in horns, Pb uptake has never been explored. Methods: Horns were collected post-mortem from three goats that had been previously used to produce blood lead reference materials for the New York State proficiency testing program. The animals were periodically dosed with lead acetate, administered orally in a capsule, over a 5 to 8-year period. Horn cross sections were taken from each animal and analyzed using synchrotron radiation-induced micro X-ray fluorescence spectrometry (SR-ARE) at the Cornell High Energy Synchrotron Source (CHESS). Results: Elemental distribution maps were obtained by SR-mu XRF for Pb, Ca, S, Se, and three other elements (Br, Zn and Cu), with values reported quantitatively as a mass fraction (mu g/g for trace elements and mg/g for Ca and S). Accumulations of Pb were clearly visible as a series of narrow "rings" in each of the horn samples analyzed. The elements Ca, S, Br, Zn, and Cu were also detected as discrete rings within each cross-section, with Br strongly correlated with S in the samples examined. A marginal increase in Se may coincide with Pb accumulation in horn cross-sections. Annual mineralization estimates based on the relative distribution of Ca and S were used to establish a tentative timeline for horn growth, with each timeline linked to the pattern of Pb accumulation in the corresponding horn cross-section sample. Conclusions: Following ingestion, absorbed Pb is eventually deposited into caprine horns, resulting in discrete accumulations or "rings." Elemental mapping by SR-mu XRF clearly show Ca-rich layers that vary with annual periodicity, consistent with previous reports of horn mineralization. Localized enrichment of Cu, Zn, Br and S appear to coincide with the keratinized regions related to the annual growth ring pattern in horns. Spatial analysis of horns for Pb accumulation may be useful as a qualitative marker of time-resolved exposures that may reflect specific periods of acute Pb absorption.

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