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Full-Text Articles in Physical Sciences and Mathematics
Some Communication Complexity Results And Their Applications, Joshua E. Brody
Some Communication Complexity Results And Their Applications, Joshua E. Brody
Dartmouth College Ph.D Dissertations
Communication Complexity represents one of the premier techniques for proving lower bounds in theoretical computer science. Lower bounds on communication problems can be leveraged to prove lower bounds in several different areas. In this work, we study three different communication complexity problems. The lower bounds for these problems have applications in circuit complexity, wireless sensor networks, and streaming algorithms. First, we study the multiparty pointer jumping problem. We present the first nontrivial upper bound for this problem. We also provide a suite of strong lower bounds under several restricted classes of protocols. Next, we initiate the study of several non-monotone …
Detecting Photographic Composites Of Famous People, Eric Kee, Hany Farid
Detecting Photographic Composites Of Famous People, Eric Kee, Hany Farid
Computer Science Technical Reports
Photos are commonly falsified by compositing two or more people into a single image. We describe how such composites can be detected by estimating a camera's intrinsic parameters. Differences in these parameters across the image are then used as evidence of tampering. Expanding on earlier work, this approach is more applicable to low-resolution images, but requires a reference image of each person in the photo as they are directly facing the camera. When considering composites of famous people, such a reference photo is easily obtained from an on-line image search.
A Correlation Attack Against User Mobility Privacy In A Large-Scale Wlan Network, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
A Correlation Attack Against User Mobility Privacy In A Large-Scale Wlan Network, Keren Tan, Guanhua Yan, Jihwang Yeo, David Kotz
Dartmouth Scholarship
User association logs collected from real-world wireless LANs have facilitated wireless network research greatly. To protect user privacy, the common practice in sanitizing these data before releasing them to the public is to anonymize users' sensitive information such as the MAC addresses of their devices and their exact association locations. In this work,we demonstrate that these sanitization measures are insufficient in protecting user privacy from a novel type of correlation attack that is based on CRF (Conditional Random Field). In such a correlation attack, the adversary observes the victim's AP (Access Point) association activities for a short period of time …
Out Of The Depths: Image Statistics Of Space, Water, And The Minuscule World, Nimit S. Dhulekar
Out Of The Depths: Image Statistics Of Space, Water, And The Minuscule World, Nimit S. Dhulekar
Dartmouth College Master’s Theses
In images of natural scenes, a consistent relationship exists between spectral power and spatial frequency. The power spectrum falls off with a form 1/f^p as spatial frequency f increases, with values of p approximately equal to 2. To quantify the extent to which this statistical characteristic is exhibited by other classes of images, we examined astronomical, underwater, and microscale images. It was found that this property holds for all three categories of images, although the value of p varies in the range 1.76 to 2.37. The second statistical characteristic computed was the angular spread of the power spectrum. This metric …
Numerical Methods For Fmri Data Analysis, Geethmala Sridaran
Numerical Methods For Fmri Data Analysis, Geethmala Sridaran
Dartmouth College Master’s Theses
Brain imaging data are increasingly analyzed via a range of machine-learning methods. In this thesis, we discuss three specific contributions to the field of neuroimaging analysis methods: 1. To apply a recently-developed technique for identifying and viewing similarity structure in neuroimaging data, in which candidate representational structures are ranked; 2. Provide side-by-side analyses of neuroimaging data by a typical non-hierarchical (SVM) versus hierarchical (Decision Tree) machine-learning classification methods; and 3. To develop a novel programming environment for PyMVPA, a current popular analysis toolbox, such that users will be able to type a small number of packaged commands to carry out …
Is Bluetooth The Right Technology For Mhealth?, Shrirang Mare, David Kotz
Is Bluetooth The Right Technology For Mhealth?, Shrirang Mare, David Kotz
Dartmouth Scholarship
Many people believe mobile healthcare (mHealth) would help alleviate the rising cost of healthcare and improve the quality of service. Bluetooth, which is the most popular wireless technology for personal medical devices, is used for most of the mHealth sensing applications. In this paper we raise the question – Is Bluetooth the right technology for mHealth? To instigate the discussion we discuss some shortcomings of Bluetooth and also point out an alternative solution.
On Usable Authentication For Wireless Body Area Networks, Cory Cornelius, David Kotz
On Usable Authentication For Wireless Body Area Networks, Cory Cornelius, David Kotz
Dartmouth Scholarship
We examine a specific security problem in wireless body area networks (WBANs), what we call the ıt one body authentication problem. That is, how can we ensure that the wireless sensors in a WBAN are collecting data about one individual and not several individuals. We explore existing solutions to this problem and provide some analysis why these solutions are inadequate. Finally, we provide some direction towards a promising solution to the problem and how it can be used to create a usably secure WBAN.
Virtual Container Attestation: Customized Trusted Containers For On-Demand Computing., Katelin A. Bailey
Virtual Container Attestation: Customized Trusted Containers For On-Demand Computing., Katelin A. Bailey
Dartmouth College Undergraduate Theses
In today's computing environment, data is moving to central locations and most computers are merely used to access the data. Today is the era of cloud computing and distributed computing, where users have control over neither data nor computation. As this trend continues there is an increasing frequency of mutually distrustful parties being forced to interact and share resources with each other in potentially dangerous situations. Therefore, there is an urgent need for a means of creating trust between two entities, or at the very least providing some means of determining the trust level of a given machine. Current approaches …
Graph Algorithms For Nmr Resonance Assignment And Cross-Link Experiment Planning, Fei Xiong
Graph Algorithms For Nmr Resonance Assignment And Cross-Link Experiment Planning, Fei Xiong
Dartmouth College Ph.D Dissertations
The study of three-dimensional protein structures produces insights into protein function at the molecular level. Graphs provide a natural representation of protein structures and associated experimental data, and enable the development of graph algorithms to analyze the structures and data. This thesis develops such graph representations and algorithms for two novel applications: structure-based NMR resonance assignment and disulfide cross-link experiment planning for protein fold determination. The first application seeks to identify correspondences between spectral peaks in NMR data and backbone atoms in a structure (from x-ray crystallography or homology modeling), by computing correspondences between a contact graph representing the structure …
Optimization Algorithms For Site-Directed Protein Recombination Experiment Planning, Wei Zheng
Optimization Algorithms For Site-Directed Protein Recombination Experiment Planning, Wei Zheng
Dartmouth College Ph.D Dissertations
Site-directed protein recombination produces improved and novel protein variants by recombining sequence fragments from parent proteins. The resulting hybrids accumulate multiple mutations that have been evolutionarily accepted together. Subsequent screening or selection identifies hybrids with desirable characteristics. In order to increase the "hit rate" of good variants, this thesis develops experiment planning algorithms to optimize protein recombination experiments. First, to improve the frequency of generating novel hybrids, a metric is developed to assess the diversity among hybrids and parent proteins. Dynamic programming algorithms are then created to optimize the selection of breakpoint locations according to this metric. Second, the trade-off …
Creating Large Disturbances In The Power Grid: Methods Of Attack After Cyber Infiltration, Loren D. Sands-Ramshaw
Creating Large Disturbances In The Power Grid: Methods Of Attack After Cyber Infiltration, Loren D. Sands-Ramshaw
Dartmouth College Undergraduate Theses
Researchers are pursuing methods of securing the cyber aspect of the U.S. power grid, one of the country's most critical infrastructures. An attacker who is able to infiltrate an Energy Management System (EMS) can instruct elements of the grid to function improperly or can skew the state information received by the control programs or operators. In addition, a cyber attack can combine multiple attacks and affect many physical locations at once. A study of the possible adverse effects an attack could generate can underline the urgency of improving grid security, contribute to a roadmap and priority list for security researchers, …
Block Sensitivity Versus Sensitivity, Karn Seth
Block Sensitivity Versus Sensitivity, Karn Seth
Dartmouth College Undergraduate Theses
Sensitivity and block sensitivity are useful and well-studied measures of computational complexity, but in spite of their similarities, the largest possible gap between them is still unknown. Rubinstein showed that this gap must be at least quadratic, and Kenyon and Kutin showed that it is at worst exponential, but many strongly suspect that the gap is indeed quadratic, or at worst polynomial. Our work shows that for a large class of functions, which includes Rubinstein's function, the quadratic gap between sensitivity and block sensitivity is the best we can possibly do.
Predictive Yasir: High Security With Lower Latency In Legacy Scada, Rouslan V. Solomakhin
Predictive Yasir: High Security With Lower Latency In Legacy Scada, Rouslan V. Solomakhin
Dartmouth College Master’s Theses
Message authentication with low latency is necessary to ensure secure operations in legacy industrial control networks, such as power grid networks. Previous authentication solutions by our lab and others looked at single messages and incurred noticeable latency. To reduce this latency, we develop Predictive YASIR, a bump-in-the-wire device that looks at broader patterns of messages. The device (1) predicts the incoming plaintext based on previous observations; (2) compresses, encrypts, and authenticates data online; and (3) pre-sends a part of ciphertext before receiving the whole plaintext. I demonstrate the performance properties of this approach by implementing it in the Scalable Simulation …
The Curious Timekeeper: Creative Thesis In Interactive Sculpture, Kate I. Schnippering
The Curious Timekeeper: Creative Thesis In Interactive Sculpture, Kate I. Schnippering
Dartmouth College Undergraduate Theses
When we interact with computers, we have set expectations about our interactive experience, operating a mouse and keyboard to elicit predictable responses on a screen. Intersecting the world of Computing with Fine Art gains us potential to innovate outside these bounds by restricting the expected performance of a computer-- setting it to a particular purpose rather than allowing it to run anyone's software. To challenge standard human-computer interaction, this work set out to create an interesting and unusual interactive experience, fully integrated into a sculpture. The approach was to design a system to form a small environment, having many components …
A 3-D Photo Forensic Analysis Of The Lee Harvey Oswald Backyard Photo, Hany Farid
A 3-D Photo Forensic Analysis Of The Lee Harvey Oswald Backyard Photo, Hany Farid
Computer Science Technical Reports
More than forty-five years after the assassination of U.S. President Kennedy theories continue to circulate suggesting that the accused assassin, Lee Harvey Oswald, acted as part of a larger conspiracy. It has been argued, for example, that incriminating photographs of Oswald were manipulated, and hence evidence of a broader plot. We describe a detailed 3-D analysis of the Oswald photos to determine if such claims of tampering are warranted.
A Note On Randomized Streaming Space Bounds For The Longest Increasing Subsequence Problem, Amit Chakrabarti
A Note On Randomized Streaming Space Bounds For The Longest Increasing Subsequence Problem, Amit Chakrabarti
Computer Science Technical Reports
The deterministic space complexity of approximating the length of the longest increasing subsequence of a stream of N integers is known to be Theta~(sqrt N). However, the randomized complexity is wide open. We show that the technique used in earlier work to establish the Omega(sqrt N) deterministic lower bound fails strongly under randomization: specifically, we show that the communication problems on which the lower bound is based have very efficient randomized protocols. The purpose of this note is to guide and alert future researchers working on this very interesting problem.
Saluki: A High-Performance Wi-Fi Sniffing Program, Keren Tan, David Kotz
Saluki: A High-Performance Wi-Fi Sniffing Program, Keren Tan, David Kotz
Dartmouth Scholarship
Building a campus-wide wireless LAN measurement system faces many efficiency, scalability and security challenges. To address these challenges, we developed a distributed Wi-Fi sniffing program called Saluki. Compared to our previous implementation and to other available sniffing programs, Saluki has the following advantages: (1) its small footprint makes it suitable for a resource-constrained Linux platform, such as those in commercial Wi-Fi access points; (2) the frame-capture rate increased more than three-fold over tcpdump with minimal frame loss; (3) all traffic between this sniffer and the back-end server was secured using 128-bit encryption; and (4) the traffic load on the backbone …
Neurophone: Brain-Mobile Phone Interface Using A Wireless Eeg Headset, Matthew K. Mukerjee
Neurophone: Brain-Mobile Phone Interface Using A Wireless Eeg Headset, Matthew K. Mukerjee
Dartmouth College Undergraduate Theses
Neural signals are everywhere just like mobile phones. We propose to use neural signals to control mobile phones for hands-free, silent and effortless human-mobile interaction. Until recently, devices for detecting neural signals have been costly, bulky and fragile. We present the design, implementation and evaluation of the NeuroPhone system, which allows neural signals to drive mobile phone applications on the iPhone using cheap off-the-shelf wireless electroencephalography (EEG) headsets. We demonstrate a mind-controlled address book dialing app, which works on similar principles to P300-speller brain-computer interfaces: the phone flashes a sequence of photos of contacts from the address book and a …
Information Cost Tradeoffs For Augmented Index And Streaming Language Recognition, Amit Chakrabarti, Graham Cormode, Ranganath Kondapally, Andrew Mcgregor
Information Cost Tradeoffs For Augmented Index And Streaming Language Recognition, Amit Chakrabarti, Graham Cormode, Ranganath Kondapally, Andrew Mcgregor
Dartmouth Scholarship
This paper makes three main contributions to the theory of communication complexity and stream computation. First, we present new bounds on the information complexity of AUGMENTED-INDEX. In contrast to analogous results for INDEX by Jain, Radhakrishnan and Sen [J. ACM, 2009], we have to overcome the significant technical challenge that protocols for AUGMENTED-INDEX may violate the “rectangle property” due to the inherent input sharing. Second, we use these bounds to resolve an open problem of Magniez, Mathieu and Nayak [STOC, 2010] that asked about the multi-pass complexity of recognizing Dyck languages. This results in a natural separation between the standard …
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
Dartmouth Scholarship
No abstract provided.
Constant Rmr Solutions To Reader Writer Synchronization, Vibhor Bhatt, Prasad Jayanti
Constant Rmr Solutions To Reader Writer Synchronization, Vibhor Bhatt, Prasad Jayanti
Computer Science Technical Reports
We study Reader-Writer Exclusion, a well-known variant of the Mutual Exclusion problem where processes are divided into two classes--readers and writers--and multiple readers can be in the Critical Section (CS) at the same time, although no process may be in the CS at the same time as a writer. Since readers don't conflict with each other, they should not obstruct each other. Specifically, the concurrent entering property must be satisfied: if all writers are in the remainder section, each reader should be able to enter the CS in a bounded number of its own steps. Three versions of the Reader-Writer …
Flexible Object Manipulation, Matthew P. Bell
Flexible Object Manipulation, Matthew P. Bell
Dartmouth College Ph.D Dissertations
Flexible objects are a challenge to manipulate. Their motions are hard to predict, and the high number of degrees of freedom makes sensing, control, and planning difficult. Additionally, they have more complex friction and contact issues than rigid bodies, and they may stretch and compress. In this thesis, I explore two major types of flexible materials: cloth and string. For rigid bodies, one of the most basic problems in manipulation is the development of immobilizing grasps. The same problem exists for flexible objects. I have shown that a simple polygonal piece of cloth can be fully immobilized by grasping all …
Quantification Of Artistic Style Through Sparse Coding Analysis In The Drawings Of Pieter Bruegel The Elder, James M. Hughes, Daniel J. Graham, Daniel N. Rockmore
Quantification Of Artistic Style Through Sparse Coding Analysis In The Drawings Of Pieter Bruegel The Elder, James M. Hughes, Daniel J. Graham, Daniel N. Rockmore
Dartmouth Scholarship
Recently, statistical techniques have been used to assist art historians in the analysis of works of art. We present a novel technique for the quantification of artistic style that utilizes a sparse coding model. Originally developed in vision research, sparse coding models can be trained to represent any image space by maximizing the kurtosis of a representation of an arbitrarily selected image from that space. We apply such an analysis to successfully distinguish a set of authentic drawings by Pieter Bruegel the Elder from another set of well-known Bruegel imitations. We show that our approach, which involves a direct comparison …
Anonytl Specification, Dan Peebles, Cory Cornelius, Apu Kapadia, David Kotz, Minho Shin, Nikos Triandopoulos
Anonytl Specification, Dan Peebles, Cory Cornelius, Apu Kapadia, David Kotz, Minho Shin, Nikos Triandopoulos
Computer Science Technical Reports
We provide a specification of AnonyTL, a domain-specific language that describes sensing tasks for mobile devices in a manner that facilitates automated reasoning about privacy.
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
On The Reliability Of Wireless Fingerprinting Using Clock Skews, Chrisil Arackaparambil, Sergey Bratus, Anna Shubina, David Kotz
Computer Science Technical Reports
Determining whether a client station should trust an access point is a known problem in wireless security. Traditional approaches to solving this problem resort to cryptography. But cryptographic exchange protocols are complex and therefore induce potential vulnerabilities in themselves. We show that measurement of clock skews of access points in an 802.11 network can be useful in this regard, since it provides fingerprints of the devices. Such fingerprints can be used to establish the first point of trust for client stations wishing to connect to an access point. Fingerprinting can also be used in the detection of fake access points. …