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222 results on '"Nguyen, Xuan Hoai"'

1. Instability of multi-mode systems with quadratic Hamiltonians

Author

Leu, Xuanloc, Nguyen, Xuan-Hoai Thi, and Lee, Jinhyoung

Subjects
Quantum Physics
Abstract

We present a novel geometric approach for determining the unique structure of a Hamiltonian and establishing an instability criterion for quantum quadratic systems. Our geometric criterion provides insights into the underlying geometric perspective of instability: A quantum quadratic system is dynamically unstable if and only if its Hamiltonian is hyperbolic. By applying our geometric method, we analyze the stability of two-mode and three-mode optomechanical systems. Remarkably, our approach demonstrates that these systems can be stabilized over a wider range of system parameters compared to the conventional rotating wave approximation (RWA) assumption. Furthermore, we reveal that the systems transit their phases from stable to unstable, when the system parameters cross specific critical boundaries. The results imply the presence of multistability in the optomechanical systems., Comment: 15 pages, 6 figures

Published
2023

2. Ultimate Precision of Direct Tomography of Wave Functions

Author

Nguyen, Xuan-Hoai Thi and Choi, Mahn-Soo

Subjects
Quantum Physics
Abstract

In contrast to the standard quantum state tomography, the direct tomography seeks the direct access to the complex values of the wave function at particular positions (i.e., the expansion coefficient in a fixed basis). Originally put forward as a special case of weak measurement, it can be extended to arbitrary measurement setup. We generalize the idea of "quantum metrology," where a real-valued phase is estimated, to the estimation of complex-valued phase, and apply it for the direct tomography of the wave function. It turns out that the reformulation can help us easily find the optimal measurements for efficient estimation. We further propose two different measurement schemes that eventually approach the Heisenberg limit. In the first scheme, the ensemble of measured system is duplicated and the replica ensemble is time-reversal transformed before the start of the measurement. In the other method, the pointers are prepared in special entangled states, either GHZ-like maximally entangled state or the symmetric Dicke state. In both methods, the real part of the parameter is estimated with a Ramsey-type interferometry while the imaginary part is estimated by amplitude measurements., Comment: 15 pages; 1 figure

Published
2019
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3. Designing and developing a mobile app (BeBo) in a randomized controlled trial study to promote breastfeeding among Vietnamese mothers

Author

Thi Thuy Duong Doan, Trung Chuyen Tran, Ngoc Minh Pham, Yun Zhao, Thi Phuong Hoa Dinh, Nguyen Xuan Hoai, Andy Lee, Colin Binns, and Thi Thu Ha Bui

Subjects
mHealth, Smartphone, App, Breastfeeding, Vietnam, Pediatrics, RJ1-570, Public aspects of medicine, RA1-1270
Abstract

Abstract Background Breastfeeding should begin as soon as possible after birth and continue exclusively to 6 months of age. In Vietnam, as in many other countries, breastfeeding is decreasing because of modern lifestyles and the promotion of infant formula. It is important to provide mothers, family members, and the community with the knowledge and strategies to improve breastfeeding rates. Smartphones are almost ubiquitous in Vietnam and of the potential to provide information about breastfeeding. This study aimed to document the process of designing and developing a mobile app to increase breastfeeding rates in Vietnamese women. Methods We used a four-step mixed methods approach with a literature review, formative research (22 in-depth interviews and 49 self-administered online questionnaires), and testing of prototype apps (3 focus groups discussion and external experts). Formative research and focus group discussion involved 99 participants. Finally, the revisions of the app were tested. All of the formative research was undertaken in Hanoi in 2019–2020. Target behaviors followed by key determinants, to improve breastfeeding self-efficacy were studied and this information was then applied in developing the messages and library content. Barriers and facilitators to breastfeeding were identified from literature reviews and qualitative research. The messages were targeted at not only mothers but also included fathers, mothers-in-law, or families. Results Mothers were mostly concerned about the initiation of breastfeeding, preventing and reducing difficulties encountered during breastfeeding, and nutrition for breastfeeding mothers. Mental health and well-being in the postnatal period are also concerns. Three key features to be included in the app were identified from the formative research: (1) notifications; (2) an information library; and (3) a searching function. The research found that the app should be installed during pregnancy rather than after delivery (81% vs 17%, respectively). Notifications that convey breastfeeding messages should be sent 2–3 times per week. Conclusion The development of the app followed a best practice approach, including the involvement of stakeholders and grounding in behavior change theory. The next step is to evaluate the effectiveness of the BeBo mobile app in a well-conducted randomized controlled trial. Trial registration ACTRN12619000531112.

Published
2023
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16. A Study on Fitness Representation in Genetic Programming

Author

Thi, Thuong Pham, Nguyen, Xuan Hoai, Nguyen, Tri Thanh, Kacprzyk, Janusz, Series editor, Pal, Nikhil R., Advisory editor, Bello Perez, Rafael, Advisory editor, Corchado, Emilio, Advisory editor, Hagras, Hani, Advisory editor, Kóczy, László T., Advisory editor, Kreinovich, Vladik, Advisory editor, Lin, Chin-Teng, Advisory editor, Lu, Jie, Advisory editor, Melin, Patricia, Advisory editor, Nedjah, Nadia, Advisory editor, Nguyen, Ngoc Thanh, Advisory editor, Wang, Jun, Advisory editor, Akagi, Masato, editor, Nguyen, Thanh-Thuy, editor, Vu, Duc-Thai, editor, Phung, Trung-Nghia, editor, and Huynh, Van-Nam, editor

Published
2017
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24. Examining the Diversity Property of Semantic Similarity Based Crossover

Author

Pham, Tuan Anh, Nguyen, Quang Uy, Nguyen, Xuan Hoai, O’Neill, Michael, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Krawiec, Krzysztof, editor, Moraglio, Alberto, editor, Hu, Ting, editor, Etaner-Uyar, A. Şima, editor, and Hu, Bin, editor

Published
2013
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29. Where Should We Stop? An Investigation on Early Stopping for GP Learning

Author

Nguyen, Thi Hien, Nguyen, Xuan Hoai, McKay, Bob, Nguyen, Quang Uy, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Bui, Lam Thu, editor, Ong, Yew Soon, editor, Hoai, Nguyen Xuan, editor, Ishibuchi, Hisao, editor, and Suganthan, Ponnuthurai Nagaratnam, editor

Published
2012
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30. Analysing the Effects of Diverse Operators in a Genetic Programming System

Author

Kim, MinHyeok, McKay, Bob (RI), Kim, Kangil, Nguyen, Xuan Hoai, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Coello, Carlos A. Coello, editor, Cutello, Vincenzo, editor, Deb, Kalyanmoy, editor, Forrest, Stephanie, editor, Nicosia, Giuseppe, editor, and Pavone, Mario, editor

Published
2012
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31. Evolutionary Operator Self-adaptation with Diverse Operators

Author

Kim, MinHyeok, McKay, Robert Ian (Bob), Kim, Dong-Kyun, Nguyen, Xuan Hoai, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Moraglio, Alberto, editor, Silva, Sara, editor, Krawiec, Krzysztof, editor, Machado, Penousal, editor, and Cotta, Carlos, editor

Published
2012
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32. An Investigation of Fitness Sharing with Semantic and Syntactic Distance Metrics

Author

Nguyen, Quang Uy, Nguyen, Xuan Hoai, O’Neill, Michael, Agapitos, Alexandros, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Moraglio, Alberto, editor, Silva, Sara, editor, Krawiec, Krzysztof, editor, Machado, Penousal, editor, and Cotta, Carlos, editor

Published
2012
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47. Learning General Solutions through Multiple Evaluations during Development

Author

Hoang, Tuan-Hao, McKay, R. I. (Bob), Essam, Daryl, Nguyen, Xuan Hoai, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Hornby, Gregory S., editor, Sekanina, Lukáš, editor, and Haddow, Pauline C., editor

Published
2008
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