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1. Visual Episodic Memory-based Exploration

Author

Vice, Jack, Ruiz-Sanchez, Natalie, Douglas, Pamela K., and Sukthankar, Gita

Subjects
Computer Science - Robotics, Computer Science - Computer Vision and Pattern Recognition, I.2.9
Abstract

In humans, intrinsic motivation is an important mechanism for open-ended cognitive development; in robots, it has been shown to be valuable for exploration. An important aspect of human cognitive development is $\textit{episodic memory}$ which enables both the recollection of events from the past and the projection of subjective future. This paper explores the use of visual episodic memory as a source of intrinsic motivation for robotic exploration problems. Using a convolutional recurrent neural network autoencoder, the agent learns an efficient representation for spatiotemporal features such that accurate sequence prediction can only happen once spatiotemporal features have been learned. Structural similarity between ground truth and autoencoder generated images is used as an intrinsic motivation signal to guide exploration. Our proposed episodic memory model also implicitly accounts for the agent's actions, motivating the robot to seek new interactive experiences rather than just areas that are visually dissimilar. When guiding robotic exploration, our proposed method outperforms the Curiosity-driven Variational Autoencoder (CVAE) at finding dynamic anomalies., Comment: FLAIRS 2023, 7 pages, 11 figures

Published
2024

2. Colorimetric (CIEDE2000) comparison between two shade guides used for visual evaluation of tooth whitening efficacy

Author

Paravina Rade D., Pereira-Sanchez Natalie A., Ghinea Razvan, and Powers John M.

Subjects
tooth whitening, color, dentistry, psychophysics, shade guide, Medicine
Abstract

Introduction/Objective. The objective of this study was to perform colorimetric comparison between two shade guides used for visual tooth whitening monitoring. Methods. VITA Bleachedguide 3D-Master (BG) and value scale of VITA classical A1–D4 (VC) were evaluated (n = 3) using a non-contact spectroradiometer. Ranges, distribution, and correlation among color parameters were evaluated using CIEDE2000 color difference formula. In addition, optimized whiteness index for dentistry (WID), and Yellowness Index E313 (YI) were analyzed. ANOVA and Fisher’s PLSD test at a 0.05 level of significance were used in statistical analysis. Results. The lightness (L’), chroma (C’), and hue (h’) ranges for BG were 20.4, 25.9, and 19.1, respectively. The corresponding ranges for VC were 15.3, 10.9, and 20.6. R2 values for individual color coordinate/tab arrangement were higher for BG than VC. The same is true for R2 values of pairs of color coordinates for BG/VC: L’C’ = 0.89/0.33, L’h’ = 0.88/0.53, and C’h’ = 0.70/0.51. BG also exhibited better agreement between the manufacturer’s tab arrangement with ΔE’, WID and YI. The ΔE’ between the lightest and the darkest BG and VC tab were 20.6 and 13.2, respectively. The average ΔE’ among the adjacent tabs were 1.9 (0.5) for BG (corresponding to two shade guide units, SGU) and 3.0 (1.0) for VC (1 SGU). Conclusion. VITA Bleachedguide 3D-Master exhibited wider L’, C’, ΔE’, WID, and YI ranges compared to value scale of VITA classical A1–D4 shade guide and better distribution of evaluated color parameters. This, along with the presence of several shades lighter than B1 of VC, recommends the use of BG for visual evaluation of tooth whitening efficacy.

Published
2019
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8. Whitening-dependent changes of fluorescence of extracted human teeth

Author

Sanchez, Natalie Pereira, Aleksić, Aleksandar, Dramićanin, Miroslav, Paravina, Rade D., Sanchez, Natalie Pereira, Aleksić, Aleksandar, Dramićanin, Miroslav, and Paravina, Rade D.

Abstract

Objective: To evaluate in vitro the fluorescence properties of extracted human teeth whitened with 40% hydrogen peroxide. Materials and Methods: A total of 28 extracted human teeth were pumiced for 1 minute using a low-speed dental handpiece and a disposable rubber cup. Pre-whitening fluorescence measurements (T0), maximum excitation (Ex(max)), maximum emission (Em(max)), and maximum intensity (I(max)10(8)), were performed using a spectrofluorometer. After T0 measurements, the teeth were whitened using the in-office method with 40% hydrogen peroxide, three times for 20 minutes. The fluorescence parameters were measured under the same conditions 7 and 14 days after bleaching (T1 and T2, respectively). Results: Ex(max) exhibited a broader range 7 days after whitening and decreased after 14 days. The Em(max) and I(max)10(8) displayed a narrower range after whitening. The mean Ex(max) differed significantly between the time points (F = 20.09. P LT .001). The corresponding analysis for the mean Em(max) differed significantly between the time points (F=16.69, P LT .001). The same was true for the mean I(max)10(8) (F = 9.69, P LT .001). Conclusions: Within the limitations of this study, whitening provoked statistically significant changes in fluorescence of the intact teeth in vitro.

Published
2017

9. An historical and multi-jurisdictional study of jurisdiction clauses in internaional maritime carriage contracts

Author

Sanchez, Natalie Isabelle and Bradfield, Graham

Subjects
InformationSystems_INFORMATIONSTORAGEANDRETRIEVAL, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, Shipping Law, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries)
Abstract

Includes bibliographical references., This dissertation aims to engage in an historical and multi-jurisdictional study of forum selection clauses in the context of international maritime carriage contracts by: 1. Describing the historical situation which led to the inclusion of jurisdiction clauses in maritime contracts in the first place, providing background information on their regulation, construction and validity under the law, and touching upon other important preliminary considerations ( Chapter 2 ); 2. Providing a multi-jurisdictional analysis of the national regulation and enforcement of jurisdiction clauses contained in carriage agreements ( Chapter 3 ); 3. Providing an overview of the European regulation and enforcement of jurisdiction clauses contained in carriage agreements ( Chapter 4 ) ; 4. Providing an overview of the regulation and enforcement of jurisdiction clauses under the Hamburg and Rotterdam Rules ( Chapter 5 ); and 5. Offering suggestions for achieving greater harmonization of rules on jurisdiction clauses and concluding remarks ( Chapter 6 ).

Published
2011

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