Digital Commons Network^™

Global Distribution Of Atmospheric Phosphorus Sources, Concentrations And Deposition Rates, And Anthropogenic Impacts, Natalie Mahowald, Timothy D. Jickells, Alex R. Baker, Paulo Artaxo, Claudia R. Benitez-Nelson, Gilles Bergametti, Tami C. Bond, Ying Chen, David D. Cohen, Barak Herut, Nilgun Kubilay, Remi Losno, Chao Luo, Willy Maenhaut, Kenneth A. Mcgee, Gregory S. Okin, Ronald L. Siefert, Seigen Tsukuda

Faculty Publications

[1] A worldwide compilation of atmospheric total phosphorus (TP) and phosphate (PO4) concentration and deposition flux observations are combined with transport model simulations to derive the global distribution of concentrations and deposition fluxes of TP and PO4. Our results suggest that mineral aerosols are the dominant source of TP on a global scale (82%), with primary biogenic particles (12%) and combustion sources (5%) important in nondusty regions. Globally averaged anthropogenic inputs are estimated to be ∼5 and 15% for TP and PO4, respectively, and may contribute as much as 50% to the deposition over the oligotrophic ocean where productivity may …

Graph Distances In The Data-Stream Model, Joan Feigenbaum, Sampath Kannan, Andrew Mcgregor, Siddharth Suri, Jian Zhang

Faculty Publications

We explore problems related to computing graph distances in the data-stream model. The goal is to design algorithms that can process the edges of a graph in an arbitrary order given only a limited amount of working memory. We are motivated by both the practical challenge of processing massive graphs such as the web graph and the desire for a better theoretical understanding of the data-stream model. In particular, we are interested in the trade-offs between model parameters such as per-data-item processing time, total space, and the number of passes that may be taken over the stream. These trade-offs are …

Sediment Transport Rate-Based Model For Rainfall-Induced Soil Erosion, Zhi Qiang Deng, João L.M.P. De Lima, Hoon Shin Jung

Faculty Publications

A one-dimensional mathematical model, termed sediment transport rate-based model, is developed for determining rainfall-induced soil erosion and sediment transport. The model is comprised of (1) the kinematic-wave equation for overland flow, (2) a transport rate-based advection equation for rainfall-induced soil erosion and sediment transport, and (3) a semi-Lagrangian algorithm for numerical solution of the soil erosion and sediment transport equation. A series of soil flume experiments under simulated rainfalls were conducted to simulate the overland flow and sediment transport and to test the sediment transport rate-based model. Numerical results of sediment transport rate-based model indicate that (i) hydrographs display an …

Learning-Based Fusion For Data Deduplication, Sabra Dinerstein, Parris K. Egbert, Stephen W. Clyde, Jared Dinerstein

Faculty Publications

Rule-based deduplication utilizes expert domain knowledge to identify and remove duplicate data records. Achieving high accuracy in a rule-based system requires the creation of rules containing a good combination of discriminatory clues. Unfortunately, accurate rule-based deduplication often requires significant manual tuning of both the rules and the corresponding thresholds. This need for manual tuning reduces the efficacy of rule-based deduplication and its applicability to real-world data sets. No adequate solution exists for this problem. We propose a novel technique for rule-based deduplication. We apply individual deduplication rules, and combine the resultant match scores via learning-based information fusion. We show empirically …

Estimating Tmr Reliability On Fpgas Using Markov Models, Daniel Mcmurtrey, Keith S. Morgan, Brian Pratt, Michael J. Wirthlin

Faculty Publications

This paper summarizes several reliability models for modeling FPGA reliability using Markov models.

Decision Tree Ensemble: Small Heterogeneous Is Better Than Large Homogeneous, Mike Gashler, Christophe G. Giraud-Carrier, Tony R. Martinez

Faculty Publications

Using decision trees that split on randomly selected attributes is one way to increase the diversity within an ensemble of decision trees. Another approach increases diversity by combining multiple tree algorithms. The random forest approach has become popular because it is simple and yields good results with common datasets. We present a technique that combines heterogeneous tree algorithms and contrast it with homogeneous forest algorithms. Our results indicate that random forests do poorly when faced with irrelevant attributes, while our heterogeneous technique handles them robustly. Further, we show that large ensembles of random trees are more susceptible to diminishing returns …

Nowhere To Hide: Finding Plagiarized Documents Based On Sentence Similarity, Nathaniel Gustafson, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Plagiarism is a serious problem that infringes copyrighted documents/materials, which is an unethical practice and decreases the economic incentive received by authors (owners) of the original copies. Unfortunately, plagiarism is getting worse due to the increasing number of online publications on the Web, which facilitates locating and paraphrasing information. In solving this problem, we propose a novel plagiarism-detection method, called SimPaD, which (i) establishes the degree of resemblance between any two documents D1 and D2 based on their sentence-to-sentence similarity computed by using pre-defined word-correlation factors, and (ii) generates a graphical view of sentences that are similar (or the same) …

Latent Common Genetic Components Of Obesity Traits, B. O. Tayo, R. Harders, A. Luke, X. Zhu, R. S. Cooper

Faculty Publications

Background: Obesity is rapidly becoming a global epidemic. Unlike many complex human diseases, obesity is defined not just by a single trait or phenotype, but jointly by measures of anthropometry and metabolic status. Methods: We applied maximum likelihood factor analysis to identify common latent factors underlying observed covariance in multiple obesity-related measures. Both the genetic components and the mode of inheritance of the common factors were evaluated. A total of 1775 participants from 590 families for whom measures on obesity-related traits were available were included in this study. Results: The average age of participants was 37 years, 39% of the …

Sensitivity Of Penman-Monteith Reference Crop Evapotranspiration In Tao' Er River Basin Of Northeastern China, Liqiao Liang, Lijuan Li, Li Zhang, Jiuyi Li, Bin Li

Faculty Publications

A non-dimensional relative sensitivity coefficient was employed to predict the responses of reference crop evapotranspiration (ET0) to perturbation of four climate variables in Tao'er River Basin of the northeastern China. Mean monthly ET0 and yearly ET0 from 1961 to 2005 were estimated with the FAO-56 Penman-Monteith Equation. A 45-year historical dataset of average monthly maximum/minimum air temperature, mean air temperature, wind speed, sunshine hours and relative humidity from 15 meteorological stations was used in the analysis. Results show that: 1) Sensitivity coefficients of wind speed, air temperature and sunshine hours were positive except for those of air temperature of Arxan …

Host-Pathogen Interactions, Insect Outbreaks, And Natural Selection For Disease Resistance, Bret D. Elderd, Jonathan Dushoff, Greg Dwyer

Faculty Publications

The theory of insect population dynamics has shown that heterogeneity in natural-enemy attack rates is strongly stabilizing. We tested the usefulness of this theory for outbreaking insects, many of which are attacked by infectious pathogens. We measured heterogeneity among gypsy moth larvae in their risk of infection with a nucleopolyhedrovirus, which is effectively heterogeneity in the pathogen's attack rate. Our data show that heterogeneity in infection risk in this insect is so high that it leads to a stable equilibrium in the models, which is inconsistent with the outbreaks seen in North American gypsy moth populations. Our data further suggest …

A Symplectic Manifold Homeomorphic But Not Diffeomorphic To Cp2 # 3cp2, S. Baldridge, Paul A. Kirk

Faculty Publications

In this article we construct a minimal symplectic 4-manifold and prove it is homeomorphic but not diffeomorphic to CP # 3CP . © 2008 Mathematical Sciences Publishers. 2 2

Surgery Description Of Colored Knots, Richard A. Litherland, Steven D. Wallace

Faculty Publications

The pair (K,ρ) consisting of a knot K S3 and a surjective map ρ from the knot group onto a dihedral group of order 2p for p an odd integer is said to be a p-colored knot. In [Algebr. Geom. Topol. 6(2006) 673-697] D Moskovich conjectures that there are exactly p equivalence classes of p-colored knots up to surgery along unknots in the kernel of the coloring. He shows that for p = 3 and 5 the conjecture holds and that for any odd p there are at least p distinct classes, but gives no general upper bound. We show …

Impossibility Of Extending Pólya's Theorem To "Forms" With Arbitrary Real Exponents, Charles N. Delzell

Faculty Publications

Pólya proved that if a form (homogeneous polynomial) with real coefficients is positive on the nonnegative orthant (except at the origin), then it is the quotient of two real forms with no negative coefficients. While Pólya's theorem extends, easily, from ordinary real forms to "generalized" real forms with arbitrary rational exponents, we show that it does not extend to generalized real forms with arbitrary real (possibly irrational) exponents. © 2008 Elsevier B.V. All rights reserved.

Topological Complexity Of Basis-Conjugating Automorphism Groups, Daniel C. Cohen, Goderdzi Pruidze

Faculty Publications

We compute the topological complexity of Eilenberg-Mac Lane spaces associated to the group of automorphisms of a finitely generated free group that act by conjugation on a given basis, and to certain subgroups.

Sequence Alignment With Traceback On Reconfigurable Hardware, Scott Lloyd, Quinn O. Snell

Faculty Publications

Biological sequence alignment is an essential tool used in molecular biology and biomedical applications. The growing volume of genetic data and the complexity of sequence alignment present a challenge in obtaining alignment results in a timely manner. Known methods to accelerate alignment on reconfigurable hardware only address sequence comparison, limit the sequence length, or exhibit memory and I/O bottlenecks. A space-efficient, global sequence alignment algorithm and architecture is presented that accelerates the forward scan and traceback in hardware without memory and I/O limitations. With 256 processing elements in FPGA technology, a performance gain over 300 times that of a desktop …

A Simple, Anatomically Based Correction To The Conventional Ankle Joint Center, Dustin A. Bruening, Ashlie N. Crewe, Frank L. Buczek

Faculty Publications

Background

Conventional motion analysis studies define the ankle joint center as the midpoint between the most medial and lateral aspects of the malleoli, yet research points toward a more distal joint center location. The purpose of this study was to develop and evaluate an anatomically based correction that would move the conventional ankle joint center to a more accurate location.

Methods

Lower extremity radiographs from 30 pediatric patients were analyzed retrospectively. An offset between the conventional and more accurate ankle joint centers was measured and correlated to other common anatomical measures based on conventional skin mounted marker positions. The best …

Forcing And Dynamics Of Seafloor-Water Column Exchange On A Broad Continental Shelf, William B. Savidge, Ann Gargett, Richard A. Jahnke, James R. Nelson, Dana K. Savidge, R Timothy Short, George Voulgaris

Faculty Publications

Relict sediments of elevated permeability characterize the majority of continental shelves globally (Emery, 1968). In these settings, interactions between benthic boundary layer (BBL) flows and seabed topography generate pressure fluctuations that drive advective and dispersive porewater transport, dramatically increasing the magnitude and variability of porewater solute and particulate exchange across the sediment-water interface (Huettel et al., 1996; Huettel and Rusch, 2000). On broad shallow shelves with a relatively large area-to-volume ratio, the seafloor’s role is magnified. Energetic events may reorganize bedforms across a significant fraction of the shelf, leading to altered exchange dynamics that may persist long after the organizing …

Communication On The Paper "A Reference-Dependent Regret Model For Deterministic Tradeoff Studies", Xiaoting Wang, Evangelos Triantaphyilou, Edouard Kujawski

Faculty Publications

This communication focuses on a fundamental problem related to the recently introduced Reference-Dependent Regret Model (RDRM) [E. Kujawski, Syst Eng 8(2) (2005), 119-1371 for deterministic multi-criteria decision-making. Kujawski asserted that the RDRM model satisfies three properties. The first of these properties, referred to as the "independence of dominated alternatives," seems to be an intuitive one. According to this property, the RDRM model preserves the ranking of two alternatives Ai and Aj with ranking Ai > Aj when a new alternative dominated by Ai is introduced or an old alternative dominated by Aj is dropped. In this communication it is demonstrated algebraically …

A Special-Purpose Architecture For Solving The Breakpoint Median Problem, Jason D. Bakos, Panormitis E. Elenis

Faculty Publications

In this paper, we describe the design for a co-processor for whole-genome phylogenetic reconstruction. Our current design performs a parallelized breakpoint median computation, which is an expensive component of the overall application. When implemented on a field-programmable gate array (FPGA), our hardware breakpoint median achieves a maximum speedup of 1005times over software. When the coprocessor is used to accelerate the entire reconstruction procedure, we achieve a maximum application speedup of 417times. The results in this paper suggest that FPGA-based acceleration is a promising approach for computationally expensive phylogenetic problems, in spite of the fact that the involved algorithms are based …

Maximizing Warfighter Capability Using Surveyed Necessity Measurement: Application To The Usaf F-15c Fleet, John M. Colombi, David R. Jacques, Dennis D. Strouble

Faculty Publications

Within the Department of Defense, with changing missions to counter dynamic and asymmetrical threats, the acquisition workforce strives to maximize capability for joint warfighting. How acquisition professionals measure and select capability improvements for the nation’s weapon systems is a perpetual challenge, made even more complex with constrained defense budgets. This study identifies a method for determining which upgrades should be purchased (production) for which aircraft in the F- 15C fleet by optimizing a capability proxy measure. Each upgrade’s “necessity” for a given mission area was obtained by conducting a survey of over 250 experienced F-15C pilots. The solution presented in …

Decentralized Perimeter Surveillance Using A Team Of Uavs, Randal Beard, David Casbeer, Derek Kingston

Faculty Publications

Sponsorship: NASA, AFOSR. This paper develops a distributed algorithm to maintain a current estimate of the state of the perimeter using a team of UAVs. Using notions of consensus, an algorithm is developed and shown to distribute a UAV team uniformly around the perimeter.

An Exploration Of The Effects Of A Practicum-Based Mathematics Methods Course On The Beliefs Of Elementary Preservice Teachers, Damon L. Bahr, Eula Ewing Monroe

Faculty Publications

Effects of a practicum-based elementary mathematics methods course on the beliefs of preservice teachers regarding conceptual knowledge in school mathematics were explored using a pre-post design. The intensity of those beliefs was assessed before and after the methods course using the IMAP Web-Based Beliefs Survey, an instrument constructed by the "Integrating Mathematics and Pedagogy" (IMAP) research group at San Diego State University. IMAP Beliefs Survey assesses belief intensity by asking respondents to react to and analyze written and video cases (Ambrose, Clement, Philipp, & Chauvot, 2004; Philipp, Ambrose, Clement, Sowder, Schappelle, Sowder Chauvot, & Thanheiser, 2005). Its use with preservice …

The State Of Balance Between Procedural Knowledge And Conceptual Understanding In Mathematics Teacher Education, Damon L. Bahr, Michael J. Bossé

Faculty Publications

The NCTM Principles and Standards for School Mathematics calls for a balance between conceptual understanding and procedural knowledge. This study reports the results of a survey distributed to AMTE members in order to discover the opinions and practices of mathematics teacher educators regarding this balance. The authors conclude that there is wide disparity of views regarding the meaning of the terms "conceptual" and "procedural" as well as the meaning "balance" between the two, in terms of what constitutes mathematics, the learning and teaching of mathematics, and the assessment of mathematical proficiency.

Search For Gravitational-Wave Bursts From Soft Gamma Repeaters, B. Abbott, R. Abbott, R. Adhikari, P. Ajith, B. Allen, G. Allen, R. S. Amin, S. B. Anderson, W. G. Anderson, M. A. Arain, M. Araya, H. Armandula, P. Armor, Y. Aso, S. Aston, P. Aufmuth, C. Aulbert, S. Babak, S. Ballmer, H. Bantilan, B. C. Barish, C. Barker, D. Barker, B. Barr, P. Barriga, M. A. Barton, I. Bartos, M. Bastarrika, K. Bayer, J. Betzwieser, P. T. Beyersdorf, Tiffany Z. Summerscales

Faculty Publications

We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the …

Centers For Oceans And Human Health: Contributions To An Emerging Discipline, Edward A. Laws, Lora E. Fleming, John J. Stegeman

Faculty Publications

No abstract provided.

On The Jump Behavior Of Distributions And Logarithmic Averages, Jasson Vindas, Ricardo Estrada

Faculty Publications

The jump behavior and symmetric jump behavior of distributions are studied. We give several formulas for the jump of distributions in terms of logarithmic averages, this is done in terms of Cesàro-logarithmic means of decompositions of the Fourier transform and in terms of logarithmic radial and angular local asymptotic behaviors of harmonic conjugate functions. Application to Fourier series are analyzed. In particular, we give formulas for jumps of periodic distributions in terms of Cesàro-Riesz logarithmic means and Abel-Poisson logarithmic means of conjugate Fourier series. © 2008 Elsevier Inc. All rights reserved.

Antiphase Ordering And Surface Phases In Lithium Aluminate, Richard R. Vanfleet, J. A. Simmons, D. W. Hill, M. M. C. Chou, B. H. Chai

Faculty Publications

Antiphase domains are seen in single crystal gamma lithium aluminate (gamma-LiAlO2) with 16.7 nm periodicity in the <110> direction. Alternate domains have a (1/2) [001] shift. Beta phase lithium aluminate (beta-LiAlO2) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk gamma phase. The orthorhombic beta phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal gamma phase's a and c axes (0.5168 and 0.6268 nm). The gamma and beta phases are seen to have different etch rates. The beta phase converts back to the …

A Locally Divergence-Free Interior Penalty Method For Two-Dimensional Curl-Curl Problems, Susanne C. Brenner, Fengyan Li, Li Yeng Sung

Faculty Publications

An interior penalty method for certain two-dimensional curl-curl problems is investigated in this paper. This method computes the divergence-free part of the solution using locally divergence-free discontinuous P vector fields on graded meshes. It has optimal order convergence (up to an arbitrarily small e) for the source problem and the eigenproblem. Results of numerical experiments that corroborate the theoretical results are also presented. © 2008 Society for Industrial and Applied Mathematics. 1

Improving Reversal Median Computation Using Commuting Reversals And Cycle Information, William Arndt, Jijun Tang

Faculty Publications

In the past decade, genome rearrangements have attracted increasing attention from both biologists and computer scientists as a new type of data for phylogenetic analysis. Methods for reconstructing phylogeny from genome rearrangements include distance-based methods, MCMC methods, and direct optimization methods. The latter, pioneered by Sankoff and extended with the software suites GRAPPA and MGR, is the most accurate approach, but is very limited due to the difficulty of its scoring procedure—it must solve multiple instances of the reversal median problem to compute the score of a given tree. The reversal median problem is known to be NP-hard and all …

Magnetism And Homogenization Of Microresonators, Robert V. Kohn, Stephen P. Shipman

Faculty Publications

Arrays of cylindrical metal microresonators embedded in a dielectric matrix were proposed by Pendry et al. [IEEE Trans. Microw. Theory Tech., 47 (1999), pp. 2075.2084] as a means of creating a microscopic structure that exhibits strong bulk magnetic behavior at frequencies not realized in nature. This behavior arises for H-polarized fields in the quasi-static regime, in which the scale of the microstructure is much smaller than the free-space wavelength of the fields. We carry out both formal and rigorous two-scale homogenization analyses, paying special attention to the appropriate method of averaging, which does not involve the usual cell averages. We …