Efficient Inversion of Multiple-Scattering Model for Optical Diffraction Tomography

Optical diffraction tomography relies on solving an inverse scattering problem governed by the wave equation. Classical reconstruction algorithms are based on linear approximations of the forward model (Born or Rytov), which limits their applicability to thin samples with low refractive-index contrasts. More recent works have shown the benefit of adopting nonlinear models. They account for multiple scattering and reflections, improving the quality of reconstruction. To reduce the complexity and memory requirements of these methods, we derive an explicit formula for the Jacobian matrix of the nonlinear Lippmann-Schwinger model which lends itself to an efficient evaluation of the gradient of the data- fidelity term. This allows us to deploy efficient methods to solve the corresponding inverse problem subject to sparsity constraints

Method for Assessing the Fidelity of Optical Diffraction Tomography Reconstruction Methods

We use a spatial light modulator in a diffraction tomographic system to assess the accuracy of different refractive index reconstruction algorithms. Optical phase conjugation principles through complex media, allows us to quantify the error for different refractive index reconstruction algorithms without access to the ground truth. To our knowledge, this is the first assessment technique that uses structured illumination experimentally to test the accuracy of different reconstruction schemes.Comment: 11 PAGES, 6 FIGURE

Optical Diffraction Tomography Meets Fluorescence Localization Microscopy

We show that structural information can be extracted from single molecule localization microscopy (SMLM) data. More precisely, we reinterpret SMLM data as the measures of a phaseless optical diffraction tomography system for which the illumination sources are fluorophores within the sample. Building upon this model, we propose a joint optimization framework to estimate both the refractive index map and the position of fluorescent molecules from the sole SMLM frames.Comment: Presented in ISCS2

Mechanical Artifacts in Optical Projection Tomography: Classification and Automatic Calibration

Optical projection tomography (OPT) is a powerful tool for biomedical studies. It achieves 3D visualization of mesoscopic biological samples with high spatial resolution using conventional tomographic-reconstruction algorithms. However, various artifacts degrade the quality of the reconstructed images due to experimental imperfections in the OPT instruments. While many efforts have been made to characterize and correct for these artifacts, they focus on one specific type of artifacts, whereas a comprehensive catalog of all sorts of mechanical artifacts does not currently exist. In this work, we systematically document many mechanical artifacts. We rely on a 3D description of the imaging system that uses a set of angular and translational parameters. We provide a catalog of artifacts. It lists their cause, resulting effects, and existing correction methods. Then, we introduce an automatic calibration algorithm that is able to recover the unknown system parameters fed into the final 3D iterative reconstruction algorithm for a distortion-free volumetric image. Simulations with beads data and experimental results on a fluorescent textile fiber confirm that our algorithm successfully removes miscalibration artifacts in the reconstruction

Vietnam’s Accession to the World Trade Organization: Economic Projections to 2020

This study presents a set of assessments of the long term economic effects of Vietnam’s accession to the WTO. Generally speaking, our results indicate that Vietnam would benefit from accelerating its participation in more open multilateralism. However, it is also clear from our analysis that these benefits will remain modest in the absence of comprehensive and complementary domestic economic reforms. Passive external liberalization, even when coupled with determined domestic reform, is inferior to WTO participation combined with negotiated market access and other activist multilateral agreements. Finally, our analysis shows that capital insufficiency is a very serious constraint on Vietnamese economic growth and diversification. Capital market reform can play an essential role in dynamic and sustained economic development for the country.Vietnam, WTO, Trade

PERSPECTIVES ON PERCEPTIONS AND PRACTICE THROUGH LEARNING CULTURES OF ENGLISH-SPEAKING COUNTRIES OF HIGH-QUALITY ENGLISH STUDIES PROGRAM STUDENTS, SCHOOL OF FOREIGN LANGUAGES, CAN THO UNIVERSITY, VIETNAM

The overall goal of the project is to understand the awareness or perceptions and practice of students of the High-quality English Studies program, School of Foreign Languages (SFL), Can Tho University (CTU), Vietnam when studying cultures of English-speaking countries (CESCs) to improve intercultural competence. The research on the perspectives or opinions of 200 High-quality English Studies students, 12 of them joining the semi-structured interview, about their awareness and practice through learning CESCs. The analysis would help the researcher understand the difficulties of students when studying cultural modules from English-speaking countries at SFL, CTU. The research results would suggest solutions to overcome the difficulties that students encounter, and at the same time provide factors that contribute to improving the intercultural competence of language students. Also, through the research results, despite many obstacles in the process of absorbing culture from cultural modules, students still retain their interest and love for the course-CESCs. However, it can be seen that the difficulty that many students often encounter is still cultural differences, thereby raising awareness of the need to learn cultures for students. Next is to design teaching materials to become more attractive and attractive, proactively find opportunities to communicate with foreigners.  Article visualizations