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Full-Text Articles in Physical Sciences and Mathematics

Privacy In Mobile Technology For Personal Healthcare, Sasikanth Avancha, Amit Baxi, David Kotz Nov 2012

Privacy In Mobile Technology For Personal Healthcare, Sasikanth Avancha, Amit Baxi, David Kotz

Dartmouth Scholarship

Information technology can improve the quality, efficiency, and cost of healthcare. In this survey, we examine the privacy requirements of \emphmobile\/ computing technologies that have the potential to transform healthcare. Such \emphmHealth\/ technology enables physicians to remotely monitor patients' health, and enables individuals to manage their own health more easily. Despite these advantages, privacy is essential for any personal monitoring technology. Through an extensive survey of the literature, we develop a conceptual privacy framework for mHealth, itemize the privacy properties needed in mHealth systems, and discuss the technologies that could support privacy-sensitive mHealth systems. We end with a list of …


An Optimal Lower Bound On The Communication Complexity Of Gap-Hamming-Distance, Amit Chakrabarti, Oded Regev Oct 2012

An Optimal Lower Bound On The Communication Complexity Of Gap-Hamming-Distance, Amit Chakrabarti, Oded Regev

Dartmouth Scholarship

We prove an optimal Ω(n) lower bound on the randomized communication complex- ity of the much-studied gap-hamming-distance problem. As a consequence, we obtain essentially optimal multipass space lower bounds in the data stream model for a number of fundamental prob- lems, including the estimation of frequency moments. The gap-hamming-distance problem is a communication problem, wherein Alice and Bob receive n-bit strings x and y, respectively. They are promised that the Hamming distance between x and y is either at least n/2 + √n or at most n, and their goal is to decide which of these is the case. Since …


Understanding Sharing Preferences And Behavior For Mhealth Devices, Aarathi Prasad, Jacob Sorber, Timothy Stablein, Denis Anthony, David Kotz Oct 2012

Understanding Sharing Preferences And Behavior For Mhealth Devices, Aarathi Prasad, Jacob Sorber, Timothy Stablein, Denis Anthony, David Kotz

Dartmouth Scholarship

mHealth devices offer many potential benefits to patients, health providers and others involved in the patients' healthcare. If patients are not in control of the collection and sharing of their personal health information, they will have privacy concerns even while enjoying the benefits of the devices. We investigated patients' willingness to share their personal health information, collected using mHealth devices, with their family, friends, third parties and the public. Our findings are based on a user study conducted with 41 participants. The best way to understand people's privacy concerns is to give them the opportunity to use the device and …


Who Wears Me? Bioimpedance As A Passive Biometric, Cory Cornelius, Jacob Sorber, Ronald Peterson, Joe Skinner, Ryan Halter, David Kotz Aug 2012

Who Wears Me? Bioimpedance As A Passive Biometric, Cory Cornelius, Jacob Sorber, Ronald Peterson, Joe Skinner, Ryan Halter, David Kotz

Dartmouth Scholarship

Mobile and wearable systems for monitoring health are becoming common. If such an mHealth system knows the identity of its wearer, the system can properly label and store data collected by the system. Existing recognition schemes for such mobile applications and pervasive devices are not particularly usable – they require ıt active engagement with the person (e.g., the input of passwords), or they are too easy to fool (e.g., they depend on the presence of a device that is easily stolen or lost). \par We present a wearable sensor to passively recognize people. Our sensor uses the unique electrical properties …


Privacy-Preserving Screen Capture: Closing The Loop For Medical Informatics Usability, Joseph Cooley, Sean Smith Jul 2012

Privacy-Preserving Screen Capture: Closing The Loop For Medical Informatics Usability, Joseph Cooley, Sean Smith

Computer Science Technical Reports

As information technology permeates healthcare (particularly provider-facing systems), maximizing system effectiveness requires the ability to document and analyze tricky or troublesome usage scenarios. However, real-world medical applications are typically replete with privacy-sensitive data regarding patients, diagnoses, clinicians, and EMR user interface details; any instrumentation for screen capture (capturing and recording the scenario depicted on the screen) needs to respect these privacy constraints. Furthermore, real-world medical informatics systems are typically composed of modules from many sources, mission-critical and often closed-source; any instrumentation for screen capture cannot rely on access to structured output or software internals. In this paper, we present a …


Methods Of Computing Deque Sortable Permutations Given Complete And Incomplete Information, Daniel J. Denton Jun 2012

Methods Of Computing Deque Sortable Permutations Given Complete And Incomplete Information, Daniel J. Denton

Dartmouth College Undergraduate Theses

The problem of determining which permutations can be sorted using certain switchyard networks is a venerable problem in computer science dating back to Knuth in 1968. In this work, we are interested in permutations which are sortable on a double-ended queue (called a deque), or on two parallel stacks. In 1982, Rosenstiehl and Tarjan presented an O(n) algorithm for testing whether a given permutation was sortable on parallel stacks. In the same paper, they also presented a modification giving O(n) test for sortability on a deque. We demonstrate a slight error in the version of their algorithm for testing deque …


Abortable Reader-Writer Locks Are No More Complex Than Abortable Mutex Locks, Zhiyu Liu Jun 2012

Abortable Reader-Writer Locks Are No More Complex Than Abortable Mutex Locks, Zhiyu Liu

Dartmouth College Master’s Theses

When a process attempts to acquire a mutex lock, it may be forced to wait if another process currently holds the lock. In certain applications, such as real-time operating systems and databases, indefinite waiting can cause a process to miss an important deadline. Hence, there has been research on designing abortable mutual exclusion locks, and fairly efficient algorithms of O(log n) RMR complexity have been discovered (n denotes the number of processes for which the algorithm is designed). The abort feature is just as important for a reader-writer lock as it is for a mutual exclusion lock, but to the …


Search For Trust: An Analysis And Comparison Of Ca System Alternatives And Enhancements, Alexandra C. Grant Jun 2012

Search For Trust: An Analysis And Comparison Of Ca System Alternatives And Enhancements, Alexandra C. Grant

Dartmouth College Undergraduate Theses

The security of the Public Key Infrastructure has been reevaluated in response to Certification Authority (CA) compromise which resulted in the circulation of fraudulent certificates. These rogue certificates can and have been used to execute Man-in-the-Middle attacks and gain access to users’ sensitive information. In wake of these events, there has been a call for change to the extent of either securing the current system or altogether replacing it with an alternative design. This paper will explore the following proposals which have been put forth to replace or improve the CA system with the goal of aiding in the prevention …


Constructing Simplicial Complexes Over Topological Spaces, Milka N. Doktorova Jun 2012

Constructing Simplicial Complexes Over Topological Spaces, Milka N. Doktorova

Dartmouth College Master’s Theses

The first step in topological data analysis is often the construction of a simplicial complex. This complex approximates the lost topology of a sampled point set. Current techniques often assume that the input is embedded in a metric -- often Euclidean -- space, and make significant use of the underlying geometry for efficient computation. Consequently, these techniques do not extend to non-Euclidean or non-metric spaces. In this thesis, we present an oracle-based framework for constructing simplicial complexes over arbitrary topological spaces. The framework consists of an oracle and an algorithm that builds the simplicial complex by making calls to the …


Asymptotic Statistics Of Nodal Domains Of Quantum Chaotic Billiards In The Semiclassical Limit, Kyle T. Konrad May 2012

Asymptotic Statistics Of Nodal Domains Of Quantum Chaotic Billiards In The Semiclassical Limit, Kyle T. Konrad

Dartmouth College Undergraduate Theses

Quantum chaos concerns eigenfunctions of the Laplace operator in a domain where a billiard ball would bounce chaotically. Such chaotic eigenfunctions have been conjectured to share statistical properties of their nodal domains with a simple percolation model, from which many interesting quantities can be computed analytically. We numerically test conjectures on the number and size of nodal domains of quantum chaotic eigenfunctions at very high energies, approaching the semiclassical limit. We use a highly efficient scaling method to quickly compute eigenfunctions at low resolution and interpolate to higher resolution. We computed 10^5 eigenfunctions and counted 10^9 nodal domains. Our results …


A Data Flow Tracker And Reference Monitor For Webkit And Javascriptcore, Andrew Bloomgarden May 2012

A Data Flow Tracker And Reference Monitor For Webkit And Javascriptcore, Andrew Bloomgarden

Dartmouth College Undergraduate Theses

Browser security revolves around the same-origin policy, but it does not defend against all attacks as evidenced by the prevalence of cross-site scripting attacks. Rather than solve that attack in particular, I have opted for a more general solution. I have modified WebKit to allow data flow tracking via labels and to allow security-sensitive operations to be allowed or denied from JavaScript.


Quantitative Patterns Of Stylistic Influence In The Evolution Of Literature, James M. Hughes, Nicholas J. Foti, David C. Krakauer, Daniel N. Rockmore May 2012

Quantitative Patterns Of Stylistic Influence In The Evolution Of Literature, James M. Hughes, Nicholas J. Foti, David C. Krakauer, Daniel N. Rockmore

Dartmouth Scholarship

Literature is a form of expression whose temporal structure, both in content and style, provides a historical record of the evolution of culture. In this work we take on a quantitative analysis of literary style and conduct the first large-scale temporal stylometric study of literature by using the vast holdings in the Project Gutenberg Digital Library corpus. We find temporal stylistic localization among authors through the analysis of the similarity structure in feature vectors derived from content-free word usage, nonhomogeneous decay rates of stylistic influence, and an accelerating rate of decay of influence among modern authors. Within a given time …


Sensor-Based System For Verifying Blood-Pressure Measurement Position, Emma N. Smithayer May 2012

Sensor-Based System For Verifying Blood-Pressure Measurement Position, Emma N. Smithayer

Dartmouth College Undergraduate Theses

Mobile maternal-health programs send workers door to door to visit pregnant women in rural India and collect data such as blood pressure or weight, then send that data to doctors for review. Since the doctors do not see the data collection, ensuring correct collection methods is crucial to allow them to make good treatment decisions. However, blood-pressure measurements are sometimes taken with the patient’s arm in the wrong position, which can cause inaccurate readings. This paper describes a system consisting of an automatic blood pressure cuff with an accelerometer and force sensors attached to determine whether the arm is at …


Meshgit: Diffing And Merging Polygonal Meshes, Jonathan D. Denning, Fabio Pellacini May 2012

Meshgit: Diffing And Merging Polygonal Meshes, Jonathan D. Denning, Fabio Pellacini

Computer Science Technical Reports

This paper presents MeshGit, a practical algorithm for diffing and merging polygonal meshes. Inspired by version control for text editing, we introduce the mesh edit distance as a measure of the dissimilarity between meshes. This distance is defined as the minimum cost of matching the vertices and faces of one mesh to those of another. We propose an iterative greedy algorithm to approximate the mesh edit distance, which scales well with model complexity, providing a practical solution to our problem. We translate the mesh correspondence into a set of mesh editing operations that transforms the first mesh into the second. …


Toward Evaluating Progressive Rendering Methods In Appearance Design Tasks, Jiawei Ou, Ondrej Karlik, Jaroslav Krivanek, Fabio Pellacini May 2012

Toward Evaluating Progressive Rendering Methods In Appearance Design Tasks, Jiawei Ou, Ondrej Karlik, Jaroslav Krivanek, Fabio Pellacini

Computer Science Technical Reports

Progressive rendering is becoming a popular alternative to precomputation approaches for appearance design tasks. Images created by different progressive algorithms exhibit various kinds of visual artifacts at the early stages of computation. We present a user study that investigates the effects of these artifacts on user performance in appearance design tasks. Specifically, we ask both novice and expert subjects to perform lighting and material editing tasks with the following algorithms: random path tracing, quasi-random path tracing, progressive photon mapping, and virtual point light (VPL) rendering. Data collected from the experiments suggest that path tracing is strongly preferred to progressive photon …


Access Control Realities As Observed In A Clinical Medical Setting, Sara Sinclair, Sean Smith Apr 2012

Access Control Realities As Observed In A Clinical Medical Setting, Sara Sinclair, Sean Smith

Computer Science Technical Reports

Effective computer security requires looking not just at technology, but also at how it meshes with users in the real-world enterprises depending on it. As part of a longer-term series of projects, we have been looking at these issues-- particularly access control-- in a variety of real-world enterprises. In previous work, we looked at companies in the finance and software industries; this paper reports on a study of a hospital's access control systems. Both studies employ ethnographic methods to elicit observations on the failures of current access control technologies in large, dynamic organizations; participants in the corporate study were largely …


Access Control Hygiene And The Empathy Gap In Medical It, Yifei Wang, Sean Smith, Andrew Gettinger Apr 2012

Access Control Hygiene And The Empathy Gap In Medical It, Yifei Wang, Sean Smith, Andrew Gettinger

Computer Science Technical Reports

In theory, access control is a solved problem. In practice, large real-world enterprises still report trouble: de facto policy becomes unmanageable; users circumvent controls. These issues can be particularly critical in medical IT, such as emerging EMR and EHR, where access control errors can have serious repercussions. In this paper, we investigate how real-world EMR users think about access control when they are making policy decisions in the abstract---and when they are actually using the system in treatment scenarios. Mismatches suggest places ("empathy gaps") where new policy tools may be needed.


Wallpaper Maps, M. Douglas Mcilroy Mar 2012

Wallpaper Maps, M. Douglas Mcilroy

Computer Science Technical Reports

A wallpaper map is a conformal projection of a spherical earth onto regular polygons with which the plane can be tiled continuously. A complete set of distinct wallpaper maps that satisfy certain natural symmetry conditions is derived and illustrated. Though all of the projections have been published before, the family had not been characterized as a whole. Some wallpaper maps generalize to one-parameter subfamilies in which the sphere is pre-transformed by a conformal automorphism.


Exposing Privacy Concerns In Mhealth Data Sharing, Aarathi Prasad Feb 2012

Exposing Privacy Concerns In Mhealth Data Sharing, Aarathi Prasad

Dartmouth College Master’s Theses

Mobile health (mHealth) has become important in the field of healthcare information technology, as patients begin to use mobile devices to record their daily activities and vital signs. These devices can record personal health information even outside the hospital setting, while the patients are at home or at their workplace. However, the devices might record sensitive information that might not be relevant for medical purposes and in some cases may be misused. Patients need expressive privacy controls so that they can trade potential health benefits of the technology with the privacy risks. To provide such privacy controls, it is important …


Passive Biometrics For Pervasive Wearable Devices (Poster Paper), Cory Cornelius, Zachary Marois, Jacob Sorber, Ron Peterson, Shrirang Mare, David Kotz Feb 2012

Passive Biometrics For Pervasive Wearable Devices (Poster Paper), Cory Cornelius, Zachary Marois, Jacob Sorber, Ron Peterson, Shrirang Mare, David Kotz

Dartmouth Scholarship

Wearable devices – like the FitBit, MOTOACTV, and Jawbone UP – are increasingly becoming more pervasive whether for monitoring health and fitness, personal assistance, or home automation. While pervasive wearable devices have long been researched, we are now beginning to see the fruits of this research in the form of commercial offerings. Today, many of these commercial wearable devices are closed systems that do not interoperate with other devices a person might carry. We believe, however, these commercial offerings signal the coming of wireless body-area networks that will connect these pervasive wearable devices and leverage existing devices a user already …


An Amulet For Trustworthy Wearable Mhealth, Jacob Sorber, Minho Shin, Ronald Peterson, Cory Cornelius, Shrirang Mare, Aarathi Prasad, Zachary Marois, Emma N. Smithayer, David Kotz Feb 2012

An Amulet For Trustworthy Wearable Mhealth, Jacob Sorber, Minho Shin, Ronald Peterson, Cory Cornelius, Shrirang Mare, Aarathi Prasad, Zachary Marois, Emma N. Smithayer, David Kotz

Dartmouth Scholarship

Mobile technology has significant potential to help revolutionize personal wellness and the delivery of healthcare. Mobile phones, wearable sensors, and home-based tele-medicine devices can help caregivers and individuals themselves better monitor and manage their health. While the potential benefits of this “mHealth” technology include better health, more effective healthcare, and reduced cost, this technology also poses significant security and privacy challenges. In this paper we propose \emphAmulet, an mHealth architecture that provides strong security and privacy guarantees while remaining easy to use, and outline the research and engineering challenges required to realize the Amulet vision.


Derivation Of A Novel Efficient Supervised Learning Algorithm From Cortical-Subcortical Loops, Ashok Chandrashekar, Richard Granger Jan 2012

Derivation Of A Novel Efficient Supervised Learning Algorithm From Cortical-Subcortical Loops, Ashok Chandrashekar, Richard Granger

Dartmouth Scholarship

Although brain circuits presumably carry out powerful perceptual algorithms, few instances of derived biological methods have been found to compete favorably against algorithms that have been engineered for specific applications. We forward a novel analysis of a subset of functions of cortical-subcortical loops, which constitute more than 80% of the human brain, thus likely underlying a broad range of cognitive functions. We describe a family of operations performed by the derived method, including a non-standard method for supervised classification, which may underlie some forms of cortically dependent associative learning. The novel supervised classifier is compared against widely used algorithms for …


Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz Jan 2012

Effects Of Network Trace Sampling Methods On Privacy And Utility Metrics, Phillip A. Fazio, Keren Tan, David Kotz

Dartmouth Scholarship

Researchers choosing to share wireless-network traces with colleagues must first anonymize sensitive information, trading off the removal of information in the interest of identity protection and the preservation of useful data within the trace. While several metrics exist to quantify this privacy-utility tradeoff, they are often computationally expensive. Computing these metrics using a \emphsample\/ of the trace could potentially save precious time. In this paper, we examine several sampling methods to discover their effects on measurement of the privacy-utility tradeoff when anonymizing network traces. We tested the relative accuracy of several packet and flow-sampling methods on existing privacy and utility …