Differentially Private Publication of Sparse Data

The problem of privately releasing data is to provide a version of a dataset without revealing sensitive information about the individuals who contribute to the data. The model of differential privacy allows such private release while providing strong guarantees on the output. A basic mechanism achieves differential privacy by adding noise to the frequency counts in the contingency tables (or, a subset of the count data cube) derived from the dataset. However, when the dataset is sparse in its underlying space, as is the case for most multi-attribute relations, then the effect of adding noise is to vastly increase the size of the published data: it implicitly creates a huge number of dummy data points to mask the true data, making it almost impossible to work with. We present techniques to overcome this roadblock and allow efficient private release of sparse data, while maintaining the guarantees of differential privacy. Our approach is to release a compact summary of the noisy data. Generating the noisy data and then summarizing it would still be very costly, so we show how to shortcut this step, and instead directly generate the summary from the input data, without materializing the vast intermediate noisy data. We instantiate this outline for a variety of sampling and filtering methods, and show how to use the resulting summary for approximate, private, query answering. Our experimental study shows that this is an effective, practical solution, with comparable and occasionally improved utility over the costly materialization approach

Automated and model-free bridge damage indicators with simultaneous multi-parameter modal anomaly detection

This paper pursues a simultaneous modal parameter anomaly detection paradigm to structural damage identification inferred from vibration-based structural health monitoring (SHM) sensors, e.g., accelerometers. System Realization Using Information Matrix (SRIM) method is performed in short duration sweeping time windows for identification of state matrices, and then, modal parameters with enhanced automation. Stable modal poles collected from stability diagrams are clustered and fed into the Gaussian distribution-based anomaly detection platform. Different anomaly thresholds are examined both on frequency and damping ratio terms taking two testbed bridge structures as application means, and simplistic Boolean Operators are performed to merge univariate anomalies. The first bridge is a reinforced concrete bridge subjected to incremental damage through a series of seismic shake table experiments conducted at the University of Nevada, Reno. The second bridge is a steel arch structure at Columbia University Morningside Campus, which reflects no damage throughout the measurements, unlike the first one. Two large-scale implementations indicate the realistic performance of automated modal analysis and anomaly recognition with minimal human intervention in terms of parameter extraction and learning supervision. Anomaly detection performance, presented in this paper, shows variation according to the designated thresholds, and hence, the information retrieval metrics being considered. The methodology is well-fitted to SHM problems which require sole data-driven, scalable, and fully autonomous perspectives

Environmental tobacco smoke exposure and health disparities: 8-year longitudinal findings from a large cohort of Thai adults

BACKGROUND: In rich countries, smokers, active or passive, often belong to disadvantaged groups. Less is known of tobacco patterns in the developing world. Hence, we seek out to investigate mental and physical health consequences of smoke exposure as well as tobacco-related inequality in transitional middle-income Thailand. METHODS: We studied a nationwide cohort of 87,151 middle-aged and older adults that we have been following for eight years (2005–2013) for emerging chronic diseases. Logistic regression was used to identify attributes associated with passive smoke exposure. Longitudinal associations between smoke exposure and wellbeing (SF-8) or psychological distress (Kessler 6) were investigated with multiple linear regression or multivariate logistic regression analysis. RESULTS: A high proportion of cohort members, especially females, were passive smokers at home and at public transport stations; males were more exposed at workplace and recreational places. We observed a social gradient with more passive smoking in poorer people. We also observed a dose response relationship linking graded smoke exposures (current, former, passive, non-exposed) to less wellbeing and more psychological distress (p-trend < 0.001). Female smokers in general had less wellbeing and more distress. CONCLUSION: Our findings add to current knowledge on the impact of active and passive smoking on health in a transitional economy. Promotion of smoking cessation programs both in public and at home could also potentially reduce adverse disparities in health and wellbeing in middle and lower income settings such as Thailand.This study was supported by the International Collaborative Research Grants Scheme with joint grants from the Wellcome Trust UK (GR071587MA) and the Australian National Health and Medical Research Council (268055), and as a global health grant from the NHMRC (585426)

Design of switchable "smart" surfaces for biomedical and nanotechnological applications

Thesis (Ph. D.)--Harvard-MIT Division of Health Sciences and Technology, June 2005.Includes bibliographical references.Chapter 1. An Introduction to Self-Assembled Monolayers & Surface Characterization A brief summary of the formation, structure, and characterization techniques of self assembled monolayers (SAMs) is described. The characterization techniques include contact angle goniometry, ellipsometry, grazing-angle Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), sum-frequency generation spectroscopy (SFG), and atomic force microscopy (AFM). Chapter 2. A Reversibly Switching Surface The design of surfaces that exhibit dynamic changes in interfacial properties such as wettability in response to an electrical potential is described. The change in wetting behavior was caused by surface-confined, single-layered molecules undergoing conformational transitions between a hydrophilic and a moderately hydrophobic state. Reversible conformational transitions were confirmed both at a molecular level using sum-frequency generation spectroscopy and at a macroscopic level using contact angle measurements. This type of surface design enables amplification of conformational transitions at a molecular level to macroscopic changes in surface properties without altering the chemical identity of the surface. Such reversibly switching surfaces may open new opportunities in interfacial engineering.Chapter 3. A Synthetic Chemical Route for the Formation of Homogeneously- Mixed Self-Assembled Monolayers A novel way to produce self-assembled monolayers (SAMs) uniformly mixed on the molecular length scale is described.(cont.) Initially, a precursor SAM was formed from molecules that are derived from 16-mercaptohexadecanoic acid (MHA) and contain a globular end group. Self-assembly of these molecules resulted in a SAM that is densely packed with respect to the space-filling end groups, but shows low-density packing with respect to the hydrophobic chains. Subsequent cleavage of the space-filling end groups established a low-density SAM of MHA. A mixed monolayer of MHA and n-butanethiol was formed by backfilling the low-density monolayer of MHA with the corresponding alkanethiol. The new "mixed" SAM was characterized by optical ellipsometry, contact angle goniometry, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FT-IR), cyclic voltammetry (CV), and reductive desorption voltammetry. The results indicate a uniformly mixed monolayer as compared to a SAM generated by coadsorption of mixtures of the same MHA and n-butanethiol molecules. This approach provides a way to produce SAMs that are uniformly mixed using a synthetic chemical route, which affords considerable flexibility in composition and also in the ratio of the different molecules in the mixed SAM. Chapter 4.(cont.) Design of Oligonucleotide Arrays Using Homogeneously Mixed Self - Assembled Monolayers We have employed two quantitative techniques, quart-crystal microbalance with dissipation monitoring (QCM-D) and surface plasmon resonance imaging (SPR) to quantify the hybridization efficiency of a 25-mer oligonucleotide probe to two different surfaces: a dense 16-mercaptohexadecanoic acid self-assembled monolayer (MHA SAM) and a homogeneously-mixed (HM) SAM generated from the method described in Chapter 3 that allows for regular spacing of functional -COOH groups. This reduced density of functional groups led to reduced attachment of oligonucleotide probes to the surface, increasing the area per probe, and allowed more space in which complimentary sequence can bind. Reducing the density of immobilized probes led to the improvement in hybridization efficiency as demonstrated in both SPR and QCM-D results, which are comparable to previous reports. Our method paves the way for customizing binding efficiency and target probe density based on the distance between functional groups. By changing the headgroup size of the precursor monolayer, different distances between functional group can be formed, allowing for an ability to tailor distances between molecules. This method may allow for improvement in DNA array technology.Chapter 5. Long-Term Stability of Self-Assembled Monolayers in Biological Media The study of long term stability of self-assembled monolayer (SAM) in biological media is of importance in evaluating its usefulness for applications in implantable biochips, biosensors, or biological microelectromechanical system (bioMEMs) devices for drug delivery.(cont.) To minimize biofouling effects, researchers have investigated protein/cell adhesion resistant surface-bound materials such as poly(ethylene glycol) or oligo(ethylene glycol) terminated self-assembled monolayers. However, no long term study in biological media has been done. To address the issue of moderate to long-term stability of SAMs for bioMEMS device modification, alkanethiol and oligo(EG) terminated alkanethiol monolayers were prepared and studied after immersion in either phosphate buffer saline (PBS) or calf serum. Here, undecanethiol (CllH23SH) and tri(ethylene glycol) terminated undecanethiol (HO(C2H40)3C H22SH) self-assembled monolayers (SAMs) on clean gold surfaces were prepared and characterized. The SAMs were then immersed into either phosphate buffered saline (PBS) or calf serum. The SAM samples were emmersed and investigated using several analytical techniques at numerous points over the next 35 days. Contact angles and current densities in voltammetry changed dramatically for the PBS samples over the time period, particularly after 21 days. Results indicate substantial loss of the integrity of the SAM. Similar alterations with time were observed for the calf serum samples in both contact angle and voltammetry measurements. X-ray photoelectron spectroscopy indicates that the likely origin is desorption of the alkanethiol moiety as evidenced by appreciable loss of the S 2p signal after 35 days. Additionally, this work may serve as a starting point for further studies of surface chemical modification methods for moderate to long-term minimization of biofouling for in vivo applications.by Thanh-Nga T. Tran.Ph.D

Solving Differential-Algebraic Equations in Power Systems Dynamics with Quantum Computing

Power system dynamics are generally modeled by high dimensional nonlinear differential-algebraic equations due to a large number of generators, loads, and transmission lines. Thus, its computational complexity grows exponentially with the system size. In this paper, we aim to evaluate the alternative computing approach, particularly the use of quantum computing algorithms to solve the power system dynamics. Leveraging a symbolic programming framework, we convert the power system dynamics' DAEs into an equivalent set of ordinary differential equations (ODEs). Their data can be encoded into quantum computers via amplitude encoding. The system's nonlinearity is captured by Taylor polynomial expansion and the quantum state tensor whereas state variables can be updated by a quantum linear equation solver. Our results show that quantum computing can solve the dynamics of the power system with high accuracy whereas its complexity is polynomial in the logarithm of the system dimension.Comment: 6 pages, 8 figures, conference pape

How Digital Natives Learn and Thrive in the Digital Age: Evidence from an Emerging Economy

As a generation of ‘digital natives,’ secondary students who were born from 2002 to 2010 have various approaches to acquiring digital knowledge. Digital literacy and resilience are crucial for them to navigate the digital world as much as the real world; however, these remain under-researched subjects, especially in developing countries. In Vietnam, the education system has put considerable effort into teaching students these skills to promote quality education as part of the United Nations-defined Sustainable Development Goal 4 (SDG4). This issue has proven especially salient amid the COVID−19 pandemic lockdowns, which had obliged most schools to switch to online forms of teaching. This study, which utilizes a dataset of 1061 Vietnamese students taken from the United Nations Educational, Scientific, and Cultural Organization (UNESCO)’s “Digital Kids Asia Pacific (DKAP)” project, employs Bayesian statistics to explore the relationship between the students’ background and their digital abilities. Results show that economic status and parents’ level of education are positively correlated with digital literacy. Students from urban schools have only a slightly higher level of digital literacy than their rural counterparts, suggesting that school location may not be a defining explanatory element in the variation of digital literacy and resilience among Vietnamese students. Students’ digital literacy and, especially resilience, also have associations with their gender. Moreover, as students are digitally literate, they are more likely to be digitally resilient. Following SDG4, i.e., Quality Education, it is advisable for schools, and especially parents, to seriously invest in creating a safe, educational environment to enhance digital literacy among students

One-loop expressions for h→llˉγh\rightarrow l\bar{l}\gamma in Higgs extensions of the Standard Model

A systematic study of one-loop contributions to the decay channels $h\rightarrow l\bar{l}\gamma$ with $l=\nu_{e,\mu, \tau}, e, \mu$, performed in Higgs extended versions of the Standard Model, is presented in the 't Hooft-Veltman gauge. Analytic formulas for one-loop form factors are expressed in terms of the logarithm and di-logarithmic functions. As a result, these form factors can be reduced to those relating to the loop-induced decay processes $h\rightarrow \gamma\gamma, Z\gamma$, confirming not only previous results using different approaches but also close relations between the three kinds of the loop-induced Higgs decay rates. For phenomenological study, we focus on the two observables, namely the enhancement factors defined as ratios of the decay rates calculated between the Higgs extended versions and the standard model, and the forward-backward asymmetries of fermions, which can be used to search for Higgs extensions of the SM. We show that direct effects of mixing between neutral Higgs bosons and indirect contributions of charged Higg boson exchanges can be probed at future colliders.Comment: 39 pages, 9 Figures, 11 Tables of dat

A comprehensive evaluation of polygenic score and genotype imputation performances of human SNP arrays in diverse populations

publishedVersio