Physical Sciences and Mathematics Commons^™

Likelihood Based Population Independent Component Analysis, Ani Eloyan, Ciprian M. Crainiceanu, Brian S. Caffo

Johns Hopkins University, Dept. of Biostatistics Working Papers

Independent component analysis (ICA) is a widely used technique for blind source separation, used heavily in several scientific research areas including acoustics, electrophysiology and functional neuroimaging. We propose a scalable two-stage iterative true group ICA methodology for analyzing population level fMRI data where the number of subjects is very large. The method is based on likelihood estimators of the underlying source densities and the mixing matrix. As opposed to many commonly used group ICA algorithms the proposed method does not require significant data reduction by a twofold singular value decomposition. In addition, the method can be applied to a large …

Corrected Confidence Bands For Functional Data Using Principal Components, Jeff Goldsmith, Sonja Greven, Ciprian M. Crainiceanu

Johns Hopkins University, Dept. of Biostatistics Working Papers

Functional principal components (FPC) analysis is widely used to decompose and express functional observations. Curve estimates implicitly condition on basis functions and other quantities derived from FPC decompositions; however these objects are unknown in practice. In this paper, we propose a method for obtaining correct curve estimates by accounting for uncertainty in FPC decompositions. Additionally, pointwise and simultaneous confidence intervals that account for both model- based and decomposition-based variability are constructed. Standard mixed-model representations of functional expansions are used to construct curve estimates and variances conditional on a specific decomposition. A bootstrap procedure is implemented to understand the uncertainty in …

Breathers In Oscillator Chains With Hertzian Interactions, Guillaume James, Panos Kevrekidis, Jesus Cuevas

Panos Kevrekidis

We prove nonexistence of breathers (spatially localized and time-periodic oscillations) for a class of Fermi-Pasta-Ulam lattices representing an uncompressed chain of beads interacting via Hertz's contact forces. We then consider the setting in which an additional on-site potential is present, motivated by the Newton's cradle under the effect of gravity. Using both direct numerical computations and a simplified asymptotic model of the oscillator chain, the so-called discrete p-Schr\"odinger (DpS) equation, we show the existence of discrete breathers and study their spectral properties and mobility. Due to the fully nonlinear character of Hertzian interactions, breathers are found to be much more …

Defeating The Kalka–Teicher–Tsaban Linear Algebra Attack On The Algebraic Eraser, Dorian Goldfeld, Paul E. Gunnells

Paul Gunnells

The Algebraic Eraser (AE) is a public key protocol for shar- ing information over an insecure channel using commutative and non- commutative groups; a concrete realization is given by Colored Burau Key Agreement Protocol (CBKAP). In this paper, we describe how to choose data in CBKAP to thwart an attack by Kalka–Teicher–Tsaban.

Experimental Study Of The Role Of Physicochemical Surface Processing On The In Ability Of Mineral Dust Particles, D. Niedermeier, S. Hartmann, T. Clauss, H. Wex, A. Kiselev, R. C. Sullivan, P. J. Demott, M. D. Petters, P. Reitz, J. Schneider, E. Mikhailov, B. Sierau, O. Stetzer, B. Reimann, U. Bundke, R. A. Shaw, A. Buchholz, T. F. Mentel, F. Stratmann

Michigan Tech Publications

During the measurement campaign FROST 2 (FReezing Of duST 2), the Leipzig Aerosol Cloud Interaction Simulator (LACIS) was used to investigate the influence of various surface modifications on the ice nucleating ability of Arizona Test Dust (ATD) particles in the immersion freezing mode. The dust particles were exposed to sulfuric acid vapor, to water vapor with and without the addition of ammonia gas, and heat using a thermodenuder operating at 250 °C. Size selected, quasi monodisperse particles with a mobility diameter of 300 nm were fed into LACIS and droplets grew on these particles such that each droplet contained a …

Biomimetic Broadband Antireflection Gratings On Solar-Grade Multicrystalline Silicon Wafers, Blayne M. Phillips, Peng Jiang, Bin Jiang

Mathematics and Statistics Faculty Publications and Presentations

The authors report a simple and scalable bottom-up technique for fabricating broadband antireflection gratings on solar-grade multicrystalline silicon (mc-Si) wafers. A Langmuir-Blodgett process is developed to assemble close-packed silica microspheres on rough mc-Si substrates. Subwavelength moth-eye pillars can then be patterned on mc-Si by using the silica microspheres as structural template. Hemispherical reflectance measurements show that the resulting mc-Si gratings exhibit near zero reflection for a wide range of wavelengths. Both experimental results and theoretical prediction using a rigorous coupled-wave analysis model show that close-packed moth-eye arrays exhibit better antireflection performance than non-close-packed arrays due to a smoother refractive index …

A Representation Of Selected Nonmanual Signals In American Sign Language, Jerry C. Schnepp

College of Computing and Digital Media Dissertations

Computer-generated three-dimensional animation holds great promise for synthesizing utterances in American Sign Language (ASL) that are not only grammatical, but believable by members of the Deaf community. Animation poses several challenges stemming from the massive amounts of data necessary to specify the movement of three-dimensional geometry, and there is no current system that facilitates the synthesis of nonmanual signals. However, the linguistics of ASL can aid in surmounting the challenge by providing structure and rules for organizing the data.

This work presents a first method for representing ASL linguistic and extralinguistic processes that involve the face. Any such representation must …

Terapixel Imaging Of Cosmological Simulations, Yu Feng, Rupert Croft, Tiziana Di Matteo, Nishikanta Khandai, Randy Sargent, Illah Nourbakhsh, Paul Dille, Chris Bartley, Volker Springel, Anirban Jana, Jeffrey Gardner

Randy Sargent

The increasing size of cosmological simulations has led to the need for new visualization techniques. We focus on smoothed particle hydrodynamic (SPH) simulations run with the GADGET code and describe methods for visually accessing the entire simulation at full resolution. The simulation snapshots are rastered and processed on supercomputers into images that are ready to be accessed through a Web interface (GigaPan). This allows any scientist with a Web browser to interactively explore simulation data sets in both spatial and temporal dimensions and data sets which in their native format can be hundreds of terabytes in size or more. We …

Lake Samish Water Monitoring Project 2011b Final Report, Robin A. Matthews, Joan Vandersypen

Lake Samish

Lake Samish is a valuable aquatic resource, providing public access for boating, fishing, swimming, picnicking, and other water and lakeshore activities. Residents around the lake enjoy outstanding views of both the lake and its surrounding watershed, and the lake serves as a water supply for many of the lakeshore residents. Lake Samish is located in the Washington State Department of Ecology’s Water Resource Inventory Area #3 (WRIA 3), and discharges into Friday Creek, a salmon spawning tributary of the Samish River.

Lake Samish experiences periodic algal blooms, including blooms of potentially toxic cyanobacteria. The major goal of the monitoring project …

Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin

Publications

This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by nonspinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for 6 different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one …

Time Evolution Of The Reverse Shock In Sn 1006, P. Frank Winkler, Andrew J. S. Hamilton, Knox S. Long, Robert A. Fesen

Dartmouth Scholarship

The Schweizer-Middleditch star, located behind the SN 1006 remnant and near its center in projection, provides the opportunity to study cold, expanding ejecta within the SN 1006 shell through UV absorption. Especially notable is an extremely sharp red edge to the Si II 1260 Å feature, which stems from the fastest moving ejecta on the far side of the SN 1006 shell—material that is just encountering the reverse shock. Comparing Hubble Space Telescope far-UV spectra obtained with the Cosmic Origins Spectrograph in 2010 and with the Space Telescope Imaging Spectrograph in 1999, we have measured the change in this feature …

Reusing Shares In Secret Sharing Schemes, Yuliang Zheng, Thomas Hardjono, Jennifer Seberry

Professor Jennifer Seberry

A (t, w) threshold scheme is a method for sharing a secret among w shareholders so that the collaboration of at least t shareholders is required in order to reconstruct the shared secret. This paper is concerned with the re-use of shares possessed by shareholders in threshold schemes. We propose a simple (t, w) threshold scheme based on the use of cryptographically strong pseudo-random functions and universal hash functions. A remarkable advantage of the scheme is that a shareholder can use a single string in the share of many different secrets; in particular, a shareholder need not be given a …

On Integer Matrices Obeying Certain Matrix Equations, Jennifer Seberry

Professor Jennifer Seberry

We discuss integer matrices B of odd order v which satisfy Br = ± B, BBr = vI - J, BJ = O. Matrices of this kind which have zero diagonal and other elements ± 1 give rise to skew-Hadamard and n-type matrices; we show that the existence of a skew-Hadamard (n-type) matrix of order h implies the existence of skew-Hadamard (n-type) matrices of orders (h - 1)5 + 1 and (h - 1)7 + 1. Finally we show that, although there are matrices B with elements other than ± 1 and 0, the equations force considerable restrictions on the …

On The Distribution Of The Permanent Of Cyclic (0,1) Matrices, Evi Nemeth, Jennifer Seberry, Michael Shu

Professor Jennifer Seberry

Some results are obtained on the permanent of cyclic (0,1) matrices which support the conjecture that for such matrices of prime order p the number of distinct values the permanent attains is of order p. Writing e(r) for the number of distinct values the permanent of cyclic (0,1) matrices of order n can attain we found e(5) = 6, e(6) = 12, e(7) = 9, e(8) = 11, e(9) = 21, e(10) ≤ 44, and e(11) ≤ 30. It is easy to show e(p) ≤ 1/p(2p-2)+2, p prime, but these answers are considerably smaller. We obtain formulae for the permanent …

Maximal Ternary Codes And Plotkin's Bound, Conrad Mackenzie, Jennifer Seberry

Professor Jennifer Seberry

The analogue of Plotkin's bound is developed for ternary codes with high distance relative to length. Generalized Hadamard matrices are used to obtain codes which meet these bounds. The ternary analogue of Levenshtein's construction is discussed and maximal codes constructed.

Supplementary Difference Sets And Optimal Designs, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry

Professor Jennifer Seberry

D-optimal designs of order n = 2v ≡ 2 (mod 4), where q is a prime power and v = q2 + q + 1 are constructed using two methods, one with supplementary difference sets and the other using projective planes more directly. An infinite family of Hadamard matrices of order n = 4v with maximum excess (n) = n√n - 3 where q is a prime power and v = q2 + q + 1 is a prime, is also constructed.

Minimal Critical Set Of A Room Square Of Order 7, Ghulam R. Chaudhry, Jennifer Seberry

Professor Jennifer Seberry

A Room square R of order r is an r x r array each of whose cells may either be empty or contain an unordered pair of objects 0,1,2,...,r, subject to the following conditions: (i) each of the objects 0,1,2.....r occurs precisely once in each row of R and precisely once in each column of R, and (ii) every possible unordered pair of objects occurs precisely once in the whole array.

New Results With Near- Yang Sequences, Marc Gysin, Jennifer Seberry

Professor Jennifer Seberry

We construct new TW -sequences, weighing matrices and orthogonal designs using near-Yang sequences. In particular we construct new OD(60(2m + 1) + 4t; 13(2m+ 1), 13(2m+ 1), 13(2m+ 1), 13(2m+ 1) and new W(60(2m+ 1) + 4t; 13s(2m+ 1))for all t ≥ O, m ≤ 30, s = 1,2,3,4.

A Generalised Testbed For Analysing Block And Stream Ciphers, Lawrence Brown, Josef Pieprzyk, R. Safavi-Naini, Jennifer Seberry

Professor Jennifer Seberry

With the recent development of a number of new ciphers, especially block ciphers, there is a need for a set of tools to help analyse them, in order to obtain some comparative measure of their relative security, and to assist in identifying any shortcomings in their design. This project uses a number of tests to provide a better determination of a cipher's capabilities than previous attempts, and incorporates them into a framework to aid extension of the testbed, through both the addition of new ciphers, and new tests. The testbed will be used for a comparative analysis of some of …

Applications Of Smartcards For Anonymous And Verifiable Databases, Thomas Hardjono, Jennifer Seberry

Professor Jennifer Seberry

In this paper we describe a practical solution towards anonymous and verifiable databases based on the use of smartcards and the recent Improved Leighton-Micali protocol for the distribution of keys. The scheme is addressed particularly to public data held in separate government databases with the aim of preventing unauthorized government institutions from gathering and merging private data concerning individuals from these separate containers. The solution can be realized through the recent Clipper Chip and smartcard technology, and its security relies on the strength of these technologies. The scheme is also extendible to mobile computing environments.

New Normal Sequences Of Length 25, Marc Gysin, Jennifer Seberry

Professor Jennifer Seberry

An introduction to binary sequences, combinatorial designs and how they are related to communication theory and computer security is given. An exhaustive search algorithm for normal sequences is presented. This is the first time that the lengths n = 24 and n = 25 have been searched through completely. No sequences of length 24 are found. It turns out that all the normal sequences of length 25 can be derived from Turyn sequences. This construction is subject to a new theorem that is given here.

Electronic Funds Transfer Point Of Sale In Australia, Ralph Gyoery, Jennifer Seberry

Professor Jennifer Seberry

The Australia wide eftpos systems was developed by the Australian Retail Banks to meet Australian conditions including a small population, which overwhehningly uses cash for transactions, a small number of banks capable of "exchange of value" settlements and enormous distances. This paper discusses the system that has evolved first involving only ATM's and banks, then extending to POS systems for retailers and non bank fmancial institutions.

On The Multiplication Theorems Of Hadamard Matrices Of Generalized Quaternion Type Using M-Structures, Jennifer Seberry, Mieko Yamada

Professor Jennifer Seberry

We show that M-structures can be extended to Hadamard matrices of generalized quaternion type and obtain multiplication type theorems which preserve the structure.

New Hadamard Matrices And Conference Matrices Obtained Via Mathon's Construction, Jennifer Seberry, Albert L. Whiteman

Professor Jennifer Seberry

We give a formulation, via (1, - 1) matrices, of Mathon's construction for conference matrices and derive a new family of conference matrices of order 5·9²r+1 + 1, t ≥ 0. This family produces a new conference matrix of order 3646 and a new Hadamard matrix of order 7292. In addition we construct new families of Hadamard matrices of orders 6.9²r+1+ 2, 10.9²t+1 + 2, 8·49·9², t ≥ 0; q2(q + 3) + 2 where q ≡ 3 (mod 4) is a prime power and 1/2(q + 5) is the order of a skew-Hadamard matrix); (q + 1)q².9t, t ≥ …

Multiplication Of Sequences With Zero Autocorrelation, Christos Koukouvinos, Stratis Kounias, Jennifer Seberry, C. H. Yang, Joel Yang

Professor Jennifer Seberry

Near normal sequences of new lengths n = 4m + 1 = 49,53,57 are constructed. The relation between a special set of near normal sequences and Golay sequences is discussed. A reformulation of Yang's powerful theorems on T-sequences is also given. We give base sequences for lengths m + p, m + p, m, m for p = 1 and m є {19, ... ,30}. Some of these are new lengths, or new decompositions into four squares for n and constructed here for the first time.

Regular Sets Of Matrices And Applications, Jennifer Seberry, Xian-Mo Zhang

Professor Jennifer Seberry

Suppose A1,....,As are (1, -1) matrices of order m satisfying AiAj=J, i,jє{1,...,s} AtiAj=AtjAi=J, i≠j, i,jє{1,...,s} ∑(AiAti + ATiAi) = 2smIm JAi = AiJ = aJ, i є {1,....,s}, a constant Call A1,.....,As a regular s-set of matrices of order m if Eq. 1-3 are satisfied and a regular s-set of regular matrices if Eq. 4 is also satisfied, these matrices were first discovered by J. Seberry and A.L. Whiteman in "New Hadamard matrices and conference matrices obtained via Mathon's construction". Graphs and Combinatorics. 4(1988), 355-377. In this paper, we prove that (i) if there exist a regular s-set of order …

Relative Compromise Of Statistical Databases, M Miller, Jennifer Seberry

Professor Jennifer Seberry

Statistical databases are databases in which only statistical type of queries are allowed. The results of the statistical queries are intended for statistical use only. However, it has been shown that using only statistical queries it is often possible to infer an individuals's value of a protected field (e.g, using various types of trackers). In such a case we say that the database has been (positively) compromised. Various types of compromise have been studied but until now attention has centred on the inference of exact information from permitted queries. In this paper we introduce a new type of compromise, the …

Generalized Bhaskar Rao Designs With Elements From Cyclic Groups Of Even Order, Andrew Bowler, Kathleen Quinn, Jennifer Seberry

Professor Jennifer Seberry

A necessary condition is given for the existence of some Generalised Bhaskar Rao designs (GBRDs) with odd block size over cyclic groups of even order. Some constructions are given for GBRDs over cyclic groups of even order with block size 3 and with block size 4. AMS Subject Classification: 05B99 Key words and phrases: Balanced Incomplete Block Designs; Generalised Bhaskar Rao Designs

Higher Dimensional Orthogonal Designs And Hadamard Matrices, Joseph Hammer, Jennifer Seberry

Professor Jennifer Seberry

When n2 elements are given they can be arranged in the form of a square, similarly when ng elements (g ≥ 3 an integer) are given they can be arranged in the form of a g-dimensional cube of side n (in short a g-cube). The position of the elements can be indicated by g suffixes.

Generation Of A Frequency Square Orthogonal To A 10 X 10 Latin Square, H C. Kirton, Jennifer Seberry

Professor Jennifer Seberry

In general it is a difficult if not impossible task to find a latin square orthogonal to a given latin square. Because of a practical problem it was required to find a frequency square orthogonal to a given latin square. We describe a computer approach which was successful in finding a (4,23) frequency square orthogonal to a given 10 x 10 latin square.