Physical Sciences and Mathematics Commons^™

Information-Theoretic Limits For Density Estimation, James Brofos

Computer Science Technical Reports

This paper is concerned with the information-theoretical limits of density estimation for Gaussian random variables with data drawn independently and with identical distributions. We apply Fano's inequality to the space of densities and an arbitrary estimator. We derive necessary conditions on the sample size for reliable density recovery and for reliable density estimation. These conditions are true simultaneously for both finitely and infinitely dimensional density spaces.

Amulet: A Secure Architecture For Mhealth Applications For Low-Power Wearable Devices, Andrés Molina-Markham, Ronald Peterson, Joseph Skinner, Tianlong Yun, Bhargav Golla, Kevin Freeman, Travis Peters, Jacob Sorber, Ryan Halter, David Kotz

Dartmouth Scholarship

Interest in using mobile technologies for health-related applications (mHealth) has increased. However, none of the available mobile platforms provide the essential properties that are needed by these applications. An mHealth platform must be (i) secure; (ii) provide high availability; and (iii) allow for the deployment of multiple third-party mHealth applications that share access to an individual's devices and data. Smartphones may not be able to provide property (ii) because there are activities and situations in which an individual may not be able to carry them (e.g., while in a contact sport). A low-power wearable device can provide higher availability, remaining …

An Assessment Of Single-Channel Emg Sensing For Gestural Input, Travis Peters

Computer Science Technical Reports

Wearable devices of all kinds are becoming increasingly popular. One problem that plagues wearable devices, however, is how to interact with them. In this paper we construct a prototype electromyography (EMG) sensing device that captures a single channel of EMG sensor data corresponding to user gestures. We also implement a machine learning pipeline to recognize gestural input received via our prototype sensing device. Our goal is to assess the feasibility of using a BITalino EMG sensor to recognize gestural input on a mobile health (mHealth) wearable device known as Amulet. We conduct three experiments in which we use the EMG …

Diagnosis-Specific Readmission Risk Prediction Using Electronic Health Data: A Retrospective Cohort Study, Courtney Hebert, Chaitanya Shivade, Randi Foraker, Jared Wasserman, Caryn Roth, Hagop Mekhjan, Stanley Lemeshow, Peter Embi

Dartmouth Scholarship

Background: Readmissions after hospital discharge are a common occurrence and are costly for both hospitals and patients. Previous attempts to create universal risk prediction models for readmission have not met with success. In this study we leveraged a comprehensive electronic health record to create readmission-risk models that were institution- and patient- specific in an attempt to improve our ability to predict readmission. Methods: This is a retrospective cohort study performed at a large midwestern tertiary care medical center. All patients with a primary discharge diagnosis of congestive heart failure, acute myocardial infarction or pneumonia over a two-year time period were …

On Opportunity Cost Bounds For The Knowledge Gradient, James Brofos

Computer Science Technical Reports

We prove an upper bound on the cumulative opportunity cost of the online knowledge gradient algorithm. We leverage the theory of martingales to yield a bound under the Gaussian assumption. Using results from information theory we are further able to provide asymptotic bounds on the cumulative opportunity cost with high probability.

Sculptflow: Visualizing Sculpting Sequences By Continuous Summarization, Jonathan D. Denning, Fabio Pellacini, Jiawei Ou

Computer Science Technical Reports

Digital sculpting is becoming ubiquitous for modeling organic shapes like characters. Artists commonly show their sculpting sessions by producing timelapses or speedup videos. But the long length of these sessions make these visualizations either too long to remain interesting or too fast to be useful. In this paper, we present SculptFlow, an algorithm that summarizes sculpted mesh sequences by repeatedly merging pairs of subsequent edits taking into account the number of summarized strokes, the magnitude of the edits, and whether they overlap. Summaries of any length are generated by stopping the merging process when the desired length is reached. We …

3dflow: Continuous Summarization Of Mesh Editing Workflows, Jonathan D. Denning, Fabio Pellacini

Computer Science Technical Reports

Mesh editing software is continually improving allowing more detailed meshes to be create efficiently by skilled artists. Many of these are interested in sharing not only the final mesh, but also their whole workflows both for creating tutorials as well as for showcasing the artist's talent, style, and expertise. Unfortunately, while creating meshes is improving quickly, sharing editing workflows remains cumbersome since time-lapsed or sped-up videos remain the most common medium. In this paper, we present 3DFlow, an algorithm that computes continuous summarizations of mesh editing workflows. 3DFlow takes as input a sequence of meshes and outputs a visualization of …

Crosscomp: Comparing Multiple Artists Performing Similar Modeling Tasks, Jonathan D. Denning, Fabio Pellacini

Computer Science Technical Reports

In two previous papers, we have focused on summarizing and visualizing the edits of a single workflow and visualizing and merging the edits of two independent workflows. In this paper, we focus on visualizing the similarities and dissimilarities of many workflows where digital artists perform similar tasks. The tasks have been chosen so each artist starts and ends with a common state. We show how to leverage the previous work to produce a visualization tool that allows for easy scanning through the workflows.

A Wearable System That Knows Who Wears It, Cory Cornelius, Ronald Peterson, Joseph Skinner, Ryan Halter, David Kotz

Dartmouth Scholarship

Body-area networks of pervasive wearable devices are increasingly used for health monitoring, personal assistance, entertainment, and home automation. In an ideal world, a user would simply wear their desired set of devices with no configuration necessary: the devices would discover each other, recognize that they are on the same person, construct a secure communications channel, and recognize the user to which they are attached. In this paper we address a portion of this vision by offering a wearable system that unobtrusively recognizes the person wearing it. Because it can recognize the user, our system can properly label sensor data or …

Garden Of Eden: Software Packages For The Generation And Rendering Of Visually Realistic Trees And Forests, William B. Jackson

Computer Science Technical Reports

Garden of Eden is an exercise in procedural generation of lifelike worlds. It randomly generates a forest scene of realistically shaped and proportioned asymmetric trees on top of a simple topographical map. This map is then rendered in an HTML5 3D canvas, with support for user navigation. The end result of this project is a sort of game, though without any goal, narrative, or creative purpose. It is simply a static rendering of a natural environment, open for exploration, closed to manipulation, exploring how users find visual pleasure and meaning in virtual environments. The passive interaction of the user is …

Zebra: Zero-Effort Bilateral Recurring Authentication (Companion Report), Shrirang Mare, Andres Molina-Markham, Cory Cornelius, Ronald Peterson, David Kotz

Computer Science Technical Reports

We describe and evaluate Zero-Effort Bilateral Recurring Authentication (ZEBRA) in our paper that appears in IEEE Symposium on Security and Privacy, May 2014. In this report we provide a more detailed comparative evaluation of ZEBRA against other related authentication schemes. The abstract of the paper follows. Common authentication methods based on passwords, tokens, or fingerprints perform one-time authentication and rely on users to log out from the computer terminal when they leave. Users often do not log out, however, which is a security risk. The most common solution, inactivity timeouts, inevitably fail security (too long a timeout) or usability (too …

Zebra: Zero-Effort Bilateral Recurring Authentication, Shrirang Mare, Andrés Molina-Markham, Cory Cornelius, Ronald Peterson, David Kotz

Dartmouth Scholarship

Common authentication methods based on passwords, tokens, or fingerprints perform one-time authentication and rely on users to log out from the computer terminal when they leave. Users often do not log out, however, which is a security risk. The most common solution, inactivity timeouts, inevitably fail security (too long a timeout) or usability (too short a timeout) goals. One solution is to authenticate users continuously while they are using the terminal and automatically log them out when they leave. Several solutions are based on user proximity, but these are not sufficient: they only confirm whether the user is nearby but …

Fingerprinting Ieee 802.15.4 Devices With Commodity Radios, Ira Ray Jenkins, Rebecca Shapiro, Sergey Bratus, Ryan Speers, Travis Goodspeed

Computer Science Technical Reports

We present a reliable method of PHY-layer fingerprinting of IEEE 802.15.4-conformant nodes with commodity digital radio chips widely used in building inexpensive IEEE 802.15.4-conformant devices. Typically, PHY-layer fingerprinting requires software-defined radios that cost orders of magnitude more than the chips they can fingerprint; our method does not require a software-defined radio and uses the same inexpensive chips. For mission-critical systems relying on 802.15.4 devices, defense-in-depth is thus necessary. Device fingerprinting has long been an important defensive tool; reducing its cost raises its utility for defenders. We investigate new methods of fingerprinting 802.15.4 devices by exploring techniques to differentiate between multiple …

Speaking The Local Dialect: Exploiting Differences Between Ieee 802.15.4 Receivers With Commodity Radios For Fingerprinting, Targeted Attacks, And Wids Evasion, Ira Ray Jenkins, Rebecca Shapiro, Sergey Bratus, Travis Goodspeed, Ryan Speers, David Dowd

Computer Science Technical Reports

Producing IEEE 802.15.4 PHY-frames reliably accepted by some digital radio receivers, but rejected by others---depending on the receiver chip's make and model---has strong implications for wireless security. Attackers could target specific receivers by crafting "shaped charges," attack frames that appear valid to the intended target and are ignored by all other recipients. By transmitting in the unique, slightly non-compliant "dialect" of the intended receivers, attackers would be able to create entire communication streams invisible to others, including wireless intrusion detection and prevention systems (WIDS/WIPS).

These scenarios are no longer theoretic. We present methods of producing such IEEE 802.15.4 frames with …

A Computational Approach To Qualitative Analysis In Large Textual Datasets, Michael Evans

Dartmouth Scholarship

In this paper I introduce computational techniques to extend qualitative analysis into the study of large textual datasets. I demonstrate these techniques by using probabilistic topic modeling to analyze a broad sample of 14,952 documents published in major American newspapers from 1980 through 2012. I show how computational data mining techniques can identify and evaluate the significance of qualitatively distinct subjects of discussion across a wide range of public discourse. I also show how examining large textual datasets with computational methods can overcome methodological limitations of conventional qualitative methods, such as how to measure the impact of particular cases on …

Vocal Resonance As A Passive Biometric, Cory Cornelius, Zachary Marois, Jacob Sorber, Ron Peterson, Shrirang Mare, David Kotz

Computer Science Technical Reports

We anticipate the advent of body-area networks of pervasive wearable devices, whether for health monitoring, personal assistance, entertainment, or home automation. In our vision, the user can simply wear the desired set of devices, and they "just work"; no configuration is needed, and yet they discover each other, recognize that they are on the same body, configure a secure communications channel, and identify the user to which they are attached. This paper addresses a method to achieve the latter, that is, for a wearable device to identify the wearer, allowing sensor data to be properly labeled or personalized behavior to …

From Map To Dist: The Evolution Of A Large-Scale Wlan Monitoring System, Keren Tan, Chris Mcdonald, Bennet Vance, Chrisil Arackaparambil, Sergey Bratus, David Kotz

Dartmouth Scholarship

The edge of the Internet is increasingly becoming wireless. Therefore, monitoring the wireless edge is important to understanding the security and performance aspects of the Internet experience. We have designed and implemented a large-scale WLAN monitoring system, the Distributed Internet Security Testbed (DIST), at Dartmouth College. It is equipped with distributed arrays of “sniffers” that cover 210 diverse campus locations and more than 5,000 users. In this paper, we describe our approach, designs and solutions for addressing the technical challenges that have resulted from efficiency, scalability, security, and management perspectives. We also present extensive evaluation results on a production network, …