Physical Sciences and Mathematics Commons^™

A Tutorial On Radiation Oncology And Optimization, Allen G. Holder, Bill Salter

Mathematics Faculty Research

Designing radiotherapy treatments is a complicated and important task that affects patient care, and modern delivery systems enable a physician more flexibility than can be considered. Consequently, treatment design is increasingly automated by techniques of optimization, and many of the advances in the design process are accomplished by a collaboration among medical physicists, radiation oncologists, and experts in optimization. This tutorial is meant to aid those with a background in optimization in learning about treatment design. Besides discussing several optimization models, we include a clinical perspective so that readers understand the clinical issues that are often ignored in the optimization …

Global Stability Of Periodic Orbits Of Non-Autonomous Difference Equations And Population Biology, Saber Elaydi, Robert J. Sacker

Mathematics Faculty Research

Elaydi and Yakubu showed that a globally asymptotically stable(GAS) periodic orbit in an autonomous difference equation must in fact be a fixed point whenever the phase space is connected. In this paper we extend this result to periodic nonautonomous difference equations via the concept of skew-product dynamical systems. We show that for a k-periodic difference equation, if a periodic orbit of period r is GAS, then r must be a divisor of k. In particular sub-harmonic, or long periodic, oscillations cannot occur. Moreover, if r divides k we construct a non-autonomous dynamical system having minimum period k and …

Geometry Of Jump Systems, Vadim Lyubashevsky, Chad Newell, Vadim Ponomarenko

Mathematics Faculty Research

A jump system is a set of lattice points satisfying a certain "two-step" axiom. We present a variety of results concerning the geometry of these objects, including a characterization of two-dimensional jump systems, necessary (though not sufficient) properties of higher-dimensional jump systems, and a characterization of constant-sum jump systems.

Navy Personnel Planning And The Optimal Partition, Allen G. Holder

Mathematics Faculty Research

One could argue that the Navy's most important resource is its personnel, and as such, workforce planning is a crucial task. We investigate a new model and solution technique that is designed to aid in optimizing the process of assigning sailors to jobs. This procedure attempts to achieve an increased level of sailor satisfaction by providing a list of possible jobs from which a sailor may choose. We show that the optimal partition provided by an interior-point algorithm is particularly useful when designing the job lists. This follows because a strictly complementary solution to the linear programming relaxation observes all …

The Asymptotic Optimal Partition And Extensions Of The Nonsubstitution Theorem, Julio R. Hasfura-Buenaga, Allen G. Holder, Jeffrey Stuart

Mathematics Faculty Research

The data describing an asymptotic linear program rely on a single parameter, usually referred to as time, and unlike parametric linear programming, asymptotic linear programming is concerned with the steady state behavior as time increases to infinity. The fundamental result of this work shows that the optimal partition for an asymptotic linear program attains a steady state for a large class of functions. Consequently, this allows us to define an asymptotic center solution. We show that this solution inherits the analytic properties of the functions used to describe the feasible region. Moreover, our results allow significant extensions of an economics …

Chromian Spinel–Olivine Phase Chemistry And The Origin Of Primitive Basalts Of The Southern Washington Cascades, Diane R. Smith, W. P. Leeman

Geosciences Faculty Research

Geochemically diverse basalts occur in an ~160-km-wide transect that stretches across the Quaternary southern Washington Cascades (SWC) volcanic arc. Two fundamental groups of SWC basalts can be identified on the basis of major and trace element chemistry. On primitive mantle-normalized “spidergrams”, Group I lavas resemble within-plate basalts, whereas Group II lavas exhibit chemical characteristics (e.g., Nb, Ta, and Ti depletions) typical of subduction-related magmas. The primitive nature of many SWC basalts is indicated by their high MgO (>6.5 wt.%, up to 9.5 wt.%), Ni (>85 ppm) and Cr (>180 ppm) contents. Electron microprobe analyses of olivine–spinel pairs …

Stability Of Single Particle Tracers For Differentiating Between Heavy- And Light-Duty Vehicle Emissions, Deborah S. Gross, Alexander R. Barron, Ellen M. Sukovich, Benjamin S. Warren, Julia C. Jarvis, David T. Suess, Kimberly A. Prather

Faculty Work

To determine the size and chemical composition of particles derived from on-road vehicle emissions, individual particles were sampledcontinuously with an aerosol time-of-flight mass spectrometer (ATOFMS) at the Caldecott Tunnel in Northern California. In this tunnel, traffic is segregated, such that in theory only light duty vehicle emissions or a mix of heavy- (HDV) and light-duty vehicle (LDV) emissions can be sampled separately. Two studies were carried out, one in November 1997 anda secondin July 2000, time periods with average ambient temperatures of 10–15 and 26–32 1C, respectively, with the instrument operating at ambient outdoor temperatures. Analysis of the chemical composition …

The Edam Project: Mining Atmospheric Aerosol Datasets, Raghu Ramakrishnan, James J. Schauer, Lei Chen, Zheng Huang, Martin M. Shafer, Deborah S. Gross, David R. Musicant

Faculty Work

Data mining has been a very active area of research in the database, machine learning, and mathematical programming communities in recent years. EDAM (Exploratory Data Analysis and Management) is a joint project between researchers in Atmospheric Chemistry and Computer Science at Carleton College and the University of Wisconsin-Madison that aims to develop data mining techniques for advancing the state of the art in analyzing atmospheric aerosol datasets. There is a great need to better understand the sources, dynamics, and compositions of atmospheric aerosols. The traditional approach for particle measurement, which is the collection of bulk samples of particulates on filters, …

Yba2cu3o7 Electro-Magneto-Optic Effects In Ba L2,3 X-Ray Absorption Near Tc, Juana Vivó Acrivos

Faculty Publications, Chemistry

The onset of electro magneto-optic effects, observed at the Ba L2,3 edges synchrotron X-ray absorption by a YBa2Cu3O7 single crystal, 10 K above the transition temperature to superconductivity, Tc ~ 92 K is used to identify the role played by the Ba donor layer in the transition to superconductivity in the CuO2 layers. Negative permeability leads to Faraday rotation of the transmitted beam below T = 112 to 56 K for the 22 μm thick single crystal (c-axis orientation of 8π/18 relative to εX-rays) and sharp changes in the density of empty final states lead to zero transmitted radiation in …

Characterization Of The Electronic Excited-State Energetics And Solution Structure Of Lanthanide(Iii) Complexes With The Polypyridine Ligand 6,6'-Bis[Bis(2-Pyridylmethyl)Aminomethyl]-2,2'-Bipyridine, Gilles Muller, P. Gawryszewska, J. Sokolnicki, A. Dossing, J. P. Riehl, J. Legendziewicz

Faculty Publications, Chemistry

Absorption, emission, and excitation spectra for solid-state and solution of Tb(III), Dy(III), and Gd(III) complexes with the polypyridine ligand 6,6‘-bis[bis(2-pyridylmethyl)-aminomethyl]-2,2‘-bipyridine (C36H34N8) are presented. Measurements of excited-state lifetimes and quantum yields in various solvents at room temperature and 77 K are also reported and used to characterize the excited-state energetics of this system. Special attention is given to the characterization of metal-to-ligand energy transfer efficiency and mechanisms. The measurement of circularly polarized luminescence (CPL) from the solution of the Dy(III) complex following circularly polarized excitation confirms the chiral structure of the complexes under study. No CPL is present in the luminescence …

Ikum: An Integrated Web Personalization Platform Based On Content Structures And User Behavior, Magdalini Eirinaki, Joannis Vlachakis, Sarabjot Anand

Faculty Publications

Web personalization is the process of customizing a web site to the needs of each specific user or set of users, taking advantage of the knowledge acquired through the analysis of the user’s navigational behavior. The objective of the I-KnowUMine project (IKUM) is to develop an integrated platform (referred to in the paper as the “IKUM system”) that uses state of the art technology and research results from different application domains in order to provide the basis for the development of online services in a wide range of application areas, presenting personalized content, services and applications to users in a …

Fluorescence Prediction Through Computational Chemistry, Daniel Craig Lathey

Theses, Dissertations and Capstones

With the growing demand for diverse fluorescent dyes, it is imperative to find a more efficient methodology by which to synthesize dyes. Our research group has found a computational method that can efficiently predict the optical properties of a molecule before it is synthesized. By evaluating different semi-empirical methods, we have found a way to predict the fluorescence maxima. With the new ability of Hyperchem 7.5 to geometrically optimize a molecule in an excited state, we can predict not only the absorption maxima, but we can also predict the fluorescence maxima within 25 nm of the actual fluorescence.

With this …

Reduction Of The Gibbs Phenomenon Via Interpolation Using Chebyshev Polynomials, Filtering And Chebyshev-Pade' Approximations, Rob-Roy L. Mace

Theses, Dissertations and Capstones

In this manuscript, we will examine several methods of interpolation, with an emphasis on Chebyshev polynomials and the removal of the Gibbs Phenomenon. Included as an appendix are the author’s Mat- Lab implementations of Lagrange, Chebyshev, and rational interpolation methods.

Convergence Analysis Of Mcmc Method In The Study Of Genetic Linkage With Missing Data, Diana Fisher

Theses, Dissertations and Capstones

Computational infeasibility of exact methods for solving genetic linkage analysis problems has led to the development of a new collection of stochastic methods, all of which require the use of Markov chains. The purpose of this work is to investigate the complexities of missing data in pedigree analysis using the Monte Carlo Markov Chain (MCMC) method as compared to the exact results. Also, we attempt to determine an association between missing data in a familial pedigree and the convergence to stationarity of a descent graph Markov chain implemented in the stochastic method for parametric linkage analysis.

In particular, we will …

Temperature And Ph Dependence Of The Cyclization Of Creatine: A Study Via Mass Spectrometry, Brian J. Diamond

Theses, Dissertations and Capstones

The creatine to creatinine cyclization is of significant biological importance, providing energy for muscle cells and indicating proper renal function. From a chemical perspective, the rate at which creatine cyclizes to form creatinine has interested researchers since the late 1920s, but the cyclization is poorly understood both energetically and mechanistically. Mass spectroscopy was used to determine the rate of creatine cyclization as a function of temperature and pH. Using these values, the energetic parameters, activation energy and Arrhenius factor, were determined as a function of pH to better understand this reaction and ultimately determine the mechanistic process for this reaction. …

Dynamic Equations On Changing Time Scales: Dynamics Of Given Logistic Problems, Parameterization, And Convergence Of Solutions, Kelli J. Hall

Theses, Dissertations and Capstones

In this thesis we use the theory of dynamic equations on time scales to understand the changes in dynamics between difference and differen- tial equations by parameterizing the underlying domains. To illustrate where and how these changes occur, we then construct a bifurcation diagram for a simple family of dynamic equations. However, these results are only true if we can move continuously through our domains, i.e, the time scales. In the last part of this thesis, we define what it means to have a convergent sequence of time scales. Then we use this definition to prove that the limit …

Unpredictable Binary Strings, Richard Low, Mark Stamp, R. Craigen, G. Faucher

Faculty Publications, Computer Science

We examine a class of binary strings arising from considerations about stream cipher encryption: to what degree can one guarantee that the number of pairs of entries distance k apart that disagree is equal to the number that agree, for all small k? In a certain sense, a keystream with such a property achieves a degree of unpredictability. The problem is also restated combinatorially in terms of seating arrangements. We examine sequences s of length 2n in which this property holds for all k ≤ Mn, where Mn is the largest number for which this is possible among strings of …

Reduced Macrophage Apoptosis Is Associated With Accelerated Atherosclerosis In Low-Denstiy Lipoprotein Receptor-Null Mice, Michael Sinensky, J. Liu, D. P. Thweke, Y. R. Su, M. F. Linton, S. Fazio

Faculty Publications, Biological Sciences

Objective— The majority of apoptotic cells in atherosclerotic lesions are macrophages. However, the pathogenic role of macrophage apoptosis in the development of atherosclerosis remains unclear. Elevated expression of Bax, one of the pivotal proapoptotic proteins of the Bcl-2 family, has been found in human atherosclerotic plaques. Activation of Bax also occurs in free cholesterol-loaded and oxysterol-treated mouse macrophages. In this study, we examined the effect of Bax deficiency in bone marrow-derived leukocytes on the development of atherosclerosis in low-density lipoprotein receptor-null (LDLR−/−) mice. Methods and Results— Fourteen 8-week-old male LDLR−/− mice were lethally irradiated and reconstituted with either wild-type (WT) …

Mass-To-Light Ratio Gradients In Early-Type Galaxy Haloes, N. R. Napolitano, M. Capaccioli, Aaron J. Romanowsky, N. G. Douglas, M. R. Merrifield, K. Kuijken, M. Arnaboldi, O. Gerhard, K. C. Freeman

Faculty Publications

Owing to the fact that the near future should see a rapidly expanding set of probes of the halo masses of individual early-type galaxies, we introduce a convenient parameter for characterizing the halo masses from both observational and theoretical results: ∇ℓϒ, the logarithmic radial gradient of the mass-to-light ratio. Using halo density profiles from Λ-cold dark matter (CDM) simulations, we derive predictions for this gradient for various galaxy luminosities and star formation efficiencies εSF. As a pilot study, we assemble the available ∇ℓϒ data from kinematics in early-type galaxies – representing the first unbiased study of halo masses in a …

The Stepping Stone Model, Ii: Genealogies And The Infinite Sites Model, Submitted, Iljana Zähle, J. Theodore Cox, Richard Durrett

Mathematics - All Scholarship

This paper extends earlier work by Cox and Durrett, who studied the coalescence times for two lineages in the stepping stone model on the two-dimensional torus. We show that the genealogy of a sample of size n is given by a time change of Kingman’s coalescent. With DNA sequence data in mind, we investigate mutation patterns under the infinite sites model, which assumes that each mutation occurs at a new site. Our results suggest that the spatial structure of the human population contributes to the haplotype structure and a slower than expected decay of genetic correlation with distance revealed by …

Rescaled Lotka-Volterra Models Converge To Super-Brownian Motion, J. Theodore Cox, Edwin A. Perkins

Mathematics - All Scholarship

We show that a sequence of stochastic spatial Lotka–Volterra models, suitably rescaled in space and time, converges weakly to super-Brownian motion with drift. The result includes both long range and nearest neighbor models, the latter for dimensions three and above. These theorems are special cases of a general convergence theorem for perturbations of the voter model.

At The Creation: The National Forest Commission Of 1896-97, Gerald W. Williams, Char Miller

Pomona Faculty Publications and Research

Among the central forces in the creation of the legislation necessary to establish federal forestry was the National Forest Commission. Its members included some of the leading conservationists of the 1890s, including Charles Sprague Sargent and Gifford Pinchot; John Muir was an unofficial member. Its final report advocated the establishment of a national forest system and served as the basis for the so-called Organic Act, which cleared the way for active management on federal forests and grasslands. Unlike the other articles, this one contains several excerpted documents interspersed with exposition.

The 19th Century Excavation Of Kent's Cavern, England, Donald A. Mcfarlane, Joyce Lundberg

WM Keck Science Faculty Papers

Between 1858 and 1880, William Pengelly developed revolutionary new techniques for the archeological and paleontological excavation of cave deposits. His work at Brixham Cave and Kent’s Cavern, England, yielded tens of thousands of specimens from the mid-Pleistocene to the Holocene, settled the intellectual debate over the co-existence of humans and extinct mammals, and accumulated an unparalleled resource for continued study. Although the Brixham Cave work was thoroughly summarized in print, Pengelly never published the plans of his much more thorough and extensive excavations at Kent’s Cavern. Here we present a reconstructed plan of the Pengelly excavations that we hope will …

Deriving Private Information From Randomized Data, Zhengli Huang, Wenliang Du, Biao Chen

Electrical Engineering and Computer Science - All Scholarship

Randomization has emerged as a useful technique for data disguising in privacy-preserving data mining. Its privacy properties have been studied in a number of papers. Kargupta et al. challenged the randomization schemes, and they pointed out that randomization might not be able to preserve privacy. However, it is still unclear what factors cause such a security breach, how they affect the privacy preserving property of the randomization, and what kinds of data have higher risk of disclosing their private contents even though they are randomized. We believe that the key factor is the correlations among attributes. We propose two data …

An Efficient Scheme For Authenticating Public Keys In Sensor Networks, Wenliang Du, Ronghua Wang, Peng Ning

Electrical Engineering and Computer Science - All Scholarship

With the advance of technology, Public Key Cryptography (PKC) will sooner or later be widely used in wireless sensor networks. Recently, it has been shown that the performance of some public key algorithms, such as Elliptic Curve Cryptography (ECC), is already close to being practical on sensor nodes. However, the energy consumption of PKC is still expensive, especially compared to symmetric-key algorithms. To maximize the lifetime of batteries, we should minimize the use of PKC whenever possible in sensor networks. This paper investigates how to replace one of the important PKC operations–the public key authentication–with symmetric key operations that are …

Lad: Localization Anomaly Detection For Wireless Sensor Networks, Wenliang Du, Lei Fang, Peng Ning

Electrical Engineering and Computer Science - All Scholarship

In wireless sensor networks (WSNs), sensors ’ locations play a critical role in many applications. Having a GPS receiver on every sensor node is costly. In the past, a number of location discovery (localization) schemes have been proposed. Most of these schemes share a common feature: they use some special nodes, called beacon nodes, which are assumed to know their own locations (e.g., through GPS receivers or manual configuration). Other sensors discover their locations based on the reference information provided by these beacon nodes. Most of the beacon-based localization schemes assume a benign environment, where all beacon nodes are supposed …

Polymorphic Self-* Agents For Stigmergic Fault Mitigation In Large-Scale Real-Time Embedded Systems, Derek Messie, Jae C. Oh

Electrical Engineering and Computer Science - All Scholarship

Organization and coordination of agents within large-scale, complex, distributed environments is one of the primary challenges in the field of multi-agent systems. A lot of interest has surfaced recently around self-* (self-organizing, self-managing, self-optimizing, self-protecting) agents. This paper presents polymorphic self-* agents that evolve a core set of roles and behavior based on environmental cues. The agents adapt these roles based on the changing demands of the environment, and are directly implementable in computer systems applications. The design combines strategies from game theory, stigmergy, and other biologically inspired models to address fault mitigation in large-scale, real-time, distributed systems. The agents …

Global Multimedia Collaboration System, Geoffrey C. Fox, Wenjun Wu, Ahmet Uyar, Hasan Bulut, Shrideep Pallickard

Electrical Engineering and Computer Science - All Scholarship

In order to build an integrated collaboration system over heterogeneous collaboration technologies, we propose a Global Multimedia Collaboration System (Global-MMCS) based on XGSP A/V Web-Services framework. This system can integrate multiple A/V services, and support various collaboration clients and communities. Now the prototype is being developed and deployed across many universities in USA and China.

Support For High Performance Real-Time Collaboration Within The Naradabrokering Substrate, Shrideep Pallickara, Hasan Bulut, Pete Burnap, Geoffrey C. Fox, Ahmet Uyar, David Walker

Electrical Engineering and Computer Science - All Scholarship

The requirements for collaborative services, especially pertaining to order and delivery, are quite different compared to traditional distributed applications. The NaradaBrokering messaging substrate enables scalable, fault-tolerant, distributed interactions between entities, and is based on the publish/subscribe paradigm. The substrate also incorporates support for Grid and Web Service. More recently, we have incorporated services within the substrate which enable us to facilitate richer collaborative interactions. In this paper, we outline our rationale for incorporating these services and how these services interact with each other. We have conducted experiments related to profiling these services, and also on the performance and scaling of …

Grid Service Architecture For Videoconferencing, Wenjun Wu, Ahmet Uyar, Hasan Bulut, Sangyoon Oh, Geoffrey C. Fox

Electrical Engineering and Computer Science - All Scholarship

In this paper we present a scalable, integrated and service-oriented collaboration system, namely Global Multimedia Collaboration System, based on the XGSP collaboration framework and NaradaBrokering messaging middleware. This system can provide videoconferencing services to heterogeneous endpoints such as H.323, SIP, Access Grid, RealPlayer as well as cellular phone. This paper discusses the design principle, system architecture and implementation in detail. The extensive performance measurement has been made to evaluate the scalability of the system.