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15 results on '"Liu, Ta-Yuan"'

1. Robust Privatization with Multiple Tasks and the Optimal Privacy-Utility Tradeoff

Author

Liu, Ta-Yuan and Wang, I-Hsiang

Subjects
Computer Science - Information Theory
Abstract

In this work, fundamental limits and optimal mechanisms of privacy-preserving data release that aims to minimize the privacy leakage under utility constraints of a set of multiple tasks are investigated. While the private feature to be protected is typically determined and known by the sanitizer, the target task is usually unknown. To address the lack of information on the specific task, utility constraints laid on a set of multiple possible tasks are considered. The mechanism protects the specific privacy feature of the to-be-released data while satisfying utility constraints of all possible tasks in the set. First, the single-letter characterization of the rate-leakage-distortion region is derived, where the utility of each task is measured by a distortion function. It turns out that the minimum privacy leakage problem with log-loss distortion constraints and the unconstrained released rate is a non-convex optimization problem. Second, focusing on the case where the raw data consists of multiple independent components, we show that the above non-convex optimization problem can be decomposed into multiple parallel privacy funnel (PF) problems with different weightings. We explicitly derive the optimal solution to each PF problem when the private feature is a component-wise deterministic function of a data vector. The solution is characterized by a leakage-free threshold: when the utility constraint is below the threshold, the minimum leakage is zero; once the required utility level is above the threshold, the privacy leakage increases linearly. Finally, we show that the optimal weighting of each privacy funnel problem can be found by solving a linear program (LP). A sufficient released rate to achieve the minimum leakage is also derived. Numerical results are shown to illustrate the robustness of our approach against the task non-specificity., Comment: Accepted for publication in the IEEE Transactions on Information Theory

Published
2020

2. Robust Privatization With Multiple Tasks and the Optimal Privacy-Utility Tradeoff

Author

Liu, Ta-Yuan and Wang, I-Hsiang

Abstract

In this work, fundamental limits and optimal mechanisms of privacy-preserving data release that aims to minimize the privacy leakage under utility constraints of a set of multiple tasks are investigated. While the private feature to be protected is typically determined and known by the sanitizer, the target task is usually unknown. To address the lack of information on the specific task, utility constraints laid on a set of multiple possible tasks are considered. The mechanism protects the specific privacy feature of the to-be-released data while satisfying utility constraints of all possible tasks in the set. First, the single-letter characterization of the rate-leakage-distortion region is derived, where the utility of each task is measured by a distortion function. It turns out that the minimum privacy leakage problem with log-loss distortion constraints and the unconstrained released rate is a non-convex optimization problem. Second, focusing on the case where the raw data consists of multiple independent components, we show that the above non-convex optimization problem can be decomposed into multiple parallel privacy funnel (PF) problems with different weightings. We explicitly derive the optimal solution to each PF problem when the private feature is a component-wise deterministic function of a data vector. The solution is characterized by a leakage-free threshold: when the utility constraint is below the threshold, the minimum leakage is zero; once the required utility level is above the threshold, the privacy leakage increases linearly. Finally, we show that the optimal weighting of each privacy funnel problem can be found by solving a linear program (LP). A sufficient released rate to achieve the minimum leakage is also derived. Numerical results are shown to illustrate the robustness of our approach against the task non-specificity.

Published
2024
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3. On the Role of Artificial Noise in Training and Data Transmission for Secret Communications

Author

Liu, Ta-Yuan, Lin, Shih-Chun, and Hong, Y. -W. Peter

Subjects
Computer Science - Information Theory
Abstract

This work considers the joint design of training and data transmission in physical-layer secret communication systems, and examines the role of artificial noise (AN) in both of these phases. In particular, AN in the training phase is used to prevent the eavesdropper from obtaining accurate channel state information (CSI) whereas AN in the data transmission phase can be used to mask the transmission of the confidential message. By considering AN-assisted training and secrecy beamforming schemes, we first derive bounds on the achievable secrecy rate and obtain a closed-form approximation that is asymptotically tight at high SNR. Then, by maximizing the approximate achievable secrecy rate, the optimal power allocation between signal and AN in both training and data transmission phases is obtained for both conventional and AN-assisted training based schemes. We show that the use of AN is necessary to achieve a high secrecy rate at high SNR, and its use in the training phase can be more efficient than that in the data transmission phase when the coherence time is large. However, at low SNR, the use of AN provides no advantage since CSI is difficult to obtain in this case. Numerical results are presented to verify our theoretical claims., Comment: 38 pages, 5 figures, submitted to IEEE Transactions on Information Theory (submitted November 2015)

Published
2015

5. Robust Privatization with Non-Specific Tasks and the Optimal Privacy-Utility Tradeoff

Author

Liu, Ta-Yuan and Wang, I-Hsiang

Subjects
FOS: Computer and information sciences, Computer Science - Information Theory, Information Theory (cs.IT)
Abstract

Fundamental limits and optimal mechanisms of privacy-preserving data release that aim to minimize the privacy leakage under utility constraints of non-specific tasks are investigated. While the private feature is typically determined and known by the users who release their data, the specific task in which the released data is utilized is usually unknown. To address the lack of information of the specific task, utility constraints laid on a set of possible tasks are considered. The mechanism protects the privacy while satisfying utility of all possible tasks in the set. First, the single-letter characterization of the rate-leakage-distortion region is derived. Characterization of the minimum leakage under log-loss distortion and unconstrained released rate turns out to be a non-convex problem. Second, focusing on the case where the raw data consists of independent components, we show that the above problem can be decomposed into multiple parallel privacy funnel (PF) problems with different weightings. We explicitly derive the solution to each PF problem when the private feature is a deterministic function of a data component. The solution is characterized by a leakage-free threshold, and the minimum leakage is zero while the utility constraint is below the threshold. Finally, we show that the optimal weighting of each PF problem can be found by solving a linear program (LP). A sufficient released rate to achieve the minimum leakage is also derived. Numerical results are shown to illustrate the robustness of our approach against the task non-specificity. Our results can also be extended to the differential privacy metric. We show that the problem with multiple constraints can also be decomposed into multiple single-constraint problems. However, the solution to each single-constraint problem remains open and can only be solved by numerical methods., Comment: Submitted for publication

Published
2020
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11. Do people from Taiwan have higher heavy metal levels than those from Western countries?

Author

Ta-Yuan Liu, Yao-Min Hung, Wei-Chun Huang, Ming-Ling Wu, Shoa-Lin Lin, Liu, Ta-Yuan, Hung, Yao-Min, Huang, Wei-Chun, Wu, Ming-Ling, and Lin, Shoa-Lin

Subjects
HEAVY metals, ETHYLENEDIAMINETETRAACETIC acid, ARSENIC, CADMIUM, MERCURY, COMPARATIVE studies, LEAD, RESEARCH methodology, MEDICAL cooperation, OCCUPATIONS, RESEARCH, EVALUATION research, BODY burden
Abstract

Introduction: This study investigated whether heavy metal levels were higher in people from Taiwan as compared to those from Western countries.Methods: We measured the level of heavy metals (lead, mercury, arsenic and cadmium) in the blood of 40 apparently healthy adults. Since mercury does not respond to ethylenediaminetetraacetic acid (EDTA) infusion, only urine lead, arsenic and cadmium levels were determined by applying the body burden concept after calcium disodium EDTA infusion. These three heavy metals were extracted from daily urine samples for three consecutive days.Results: The mean blood lead, mercury and cadmium levels of the Taiwanese individuals (24.46 ± 9.69 µg/L, 9.64 ± 6.98 µg/L and 0.73 ± 0.27 µg/L, respectively) were greater than those of the Americans. The Taiwanese also had greater blood mercury and cadmium levels than the Germans. The first-day urine lead, arsenic and cadmium levels were 77.9%, 33.1% and 62.4%, respectively, of the total lead, arsenic and cadmium excretion during the three days. This indicates that the first-day urine lead and cadmium excretion represented most (> 60%) of the lead and cadmium excretion in those three days.Conclusion: This study demonstrated that the Taiwanese population has higher blood mercury and cadmium levels than Western populations. To study the urine lead and cadmium body burden of patients, detection of first-day, rather than three-day, urine lead and cadmium levels can be done, as the former yields results that are fairly representative, and is more time- and cost-effective. [ABSTRACT FROM AUTHOR]

Published
2017
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14. Do people from Taiwan have higher heavy metal levels than those from Western countries?

Author

Liu TY, Hung YM, Huang WC, Wu ML, and Lin SL

Subjects
Adult, Aged, Arsenic blood, Arsenic urine, Body Burden, Cadmium blood, Cadmium urine, Edetic Acid, Female, Germany, Humans, Lead blood, Lead urine, Male, Mercury blood, Mercury urine, Metals, Heavy blood, Middle Aged, Occupations, Taiwan, United States, Metals, Heavy urine
Abstract

Introduction: This study investigated whether heavy metal levels were higher in people from Taiwan as compared to those from Western countries., Methods: We measured the level of heavy metals (lead, mercury, arsenic and cadmium) in the blood of 40 apparently healthy adults. Since mercury does not respond to ethylenediaminetetraacetic acid (EDTA) infusion, only urine lead, arsenic and cadmium levels were determined by applying the body burden concept after calcium disodium EDTA infusion. These three heavy metals were extracted from daily urine samples for three consecutive days., Results: The mean blood lead, mercury and cadmium levels of the Taiwanese individuals (24.46 ± 9.69 µg/L, 9.64 ± 6.98 µg/L and 0.73 ± 0.27 µg/L, respectively) were greater than those of the Americans. The Taiwanese also had greater blood mercury and cadmium levels than the Germans. The first-day urine lead, arsenic and cadmium levels were 77.9%, 33.1% and 62.4%, respectively, of the total lead, arsenic and cadmium excretion during the three days. This indicates that the first-day urine lead and cadmium excretion represented most (> 60%) of the lead and cadmium excretion in those three days., Conclusion: This study demonstrated that the Taiwanese population has higher blood mercury and cadmium levels than Western populations. To study the urine lead and cadmium body burden of patients, detection of first-day, rather than three-day, urine lead and cadmium levels can be done, as the former yields results that are fairly representative, and is more time- and cost-effective., (Copyright: © Singapore Medical Association)

Published
2017
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15. Relationship between vitamin D deficiency and cardiovascular disease.

Author

Ku YC, Liu ME, Ku CS, Liu TY, and Lin SL

Abstract

Epidemiological studies have found that low 25-hydroxyvitamin D levels may be associated with coronary risk factors and adverse cardiovascular outcomes. Additionally, vitamin D deficiency causes an increase in parathyroid hormone, which increases insulin resistance and is associated with diabetes, hypertension, inflammation, and increased cardiovascular risk. In this review, we analyze the association between vitamin D supplementation and the reduction in cardiovascular disease. The role of vitamin D deficiency in cardiovascular morbidity and mortality is still controversial, and larger scale, randomized placebo controlled trials are needed to investigate whether oral vitamin D supplementation can reduce cardiovascular risk. Given the low cost, safety, and demonstrated benefit of higher 25-hydroxyvitamin D levels, vitamin D supplementation should become a public health priority for combating common and costly chronic cardiovascular diseases.

Published
2013
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