Digital Commons Network^™

An Ecology Problem Book, Marc Mangel, Paul Switzer, Sarah M. Eppley

Biology Faculty Publications and Presentations

This problem book has many objectives:

• To get you to think about the course each night: do not wait until the last minute to begin working on the problems.
• To get you to deal with data. Statistics courses that you take in the future will be more meaningful once you understand the kinds of data that arise in ecological studies.
• To get you to be more comfortable with theoretical and quantitative methods. Not every ecologist uses those methods, but one should not be put off by them.
• To familiarize you with material as it appears in the professional literature.

Gravity Drainage Prior To Cake Filtration, Scott A. Wells, Gregory K. Savage

Civil and Environmental Engineering Faculty Publications and Presentations

During the initial stages of a Buchner funnel or specific resistance test, gravity drainage occurs prior to application of the pressure differential. Some allow time for a small cake to form by gravity drainage. Filtrate data from the gravity drainage period can be used to determine constitutive properties of the cake under a hydrostatic pressure gradient. The constitutive properties that define the structure of the cake include the permeability and porosity as functions of the applied stress. Equations governing the drainage rate during a gravity filtration experiment assuming a constant and a non-constant average cake permeability and cake porosity were …

An Approach To Exact Modeling Of The Pwm Switch, Anas N. Al-Rabadi

Dissertations and Theses

Large number of small-signal models of de-to-de power converters exists already. These models usually use two techniques. The first is the averaging technique, such as: volt-second and current-second balance, state space averaging, and the averaged modeling approach. The other technique focuses on the exact modeling approach, such as: the application of time varying systems theory to linearize networks. One of the methodologies to apply the above techniques, is to view the three-terminal systems as a two-port network.

The aim of the work presented in this thesis is to develop a new approach, by the application of the two-port network methodology …

The Impact Of Relative Gains On Interstate Cooperation In The Areas Of Security And International Economy, Renato Corbetta

Dissertations and Theses

In the last twenty years, the issue of the impact of relative gains on interstate cooperation has been at the center of the debate between the two major schools of thought in International Relations theory, namely neoliberalism and neorealism. Over time, the relative gains problem has ceased to be a radically divisive issue and has worked as a common research program that has brought the two theoretical perspectives closer together. Both neoliberals and neorealists have set aside major questions regarding the origins of the relative gains problem and of states' preferences, and they have focused on the problem of determining …

Specification-Driven Optimization, Sheena Day

Dissertations and Theses

Traditionally, optimizing transformations have been built into compilers. The end-user has little or no control over guiding any optimizations that may be applied by the compiler. Moreover, the compiler-writer does not have a simple way to direct the optimizations. Thus, many potentially beneficial opportunities for code optimization may be lost. We have built a system that allows the user to participate in guiding source-to-source transformations via the specification of rewrite rules. A clean separation of the rules from the strategy of applying them makes the system easier to use and modify, compared to other integrated systems. This is especially relevant …

Self-Consistent Effective Binary Interaction Approximation For Strongly Coupled Multifluid Dynamics, John D. Ramshaw

Physics Faculty Publications and Presentations

An improved self-consistent effective binary diffusion approximation for multicomponent diffusion was recently described [1]. Here we develop an analogous self-consistent effective binary interaction (SCEBI) approximation for simplifying multifluid dynamical descriptions in which each fluid is strongly coupled to the other fluids by pairwise frictional forces. The net drag force on each fluid is the summation of the drag forces due to each of the other fluids. This summation is approximated by a single term proportional to the velocity of the fluid in question relative to an appropriately weighted average velocity. This approximation permits an explicit numerical solution for the fluid …

Portland State Magazine, Portland State University. Office Of University Communications

Portland State Magazine

PSU’s alumni magazine, published 2-3 times a year. In this issue: The six galleries on campus display local and national art—they also do great First Thursdays; help your child become a good speller. Plus, take a test to determine your own spelling aptitude; the food industry is finding new ways of doing business with the help of a PSU management program; when a company needs turning around, Renee Fellman is the specialist a history journal of the Pacific Rim is right at home in Cramer Hall; and more.

Will Business-Led Environmental Initiatives Grow In Agriculture?, Sandra S. Batie, David E. Ervin

Economics Faculty Publications and Presentations

This article was stimulated by a 1997 American Agricultural Economics Association annual meeting preconference designed by Batie and Ervin. The authors felt that there was considerable interest and activity in business-led environmental management (also caLLed corporate environmental management)-but most of the interest was found outside of the agricultural sector and the profession. The conference was a means to investigate the extent, motivation, and consequences of business-led poLLution prevention activities. The DuPont and the StahLbush Island Farms examples used in this article were drawn from discussions that took place at the conference and which were published in the proceedings. In the …

Effect Of Environmental Structure On Evolutionary Adaptation, Jeffrey Alan Fletcher, Mark A. Bedau, Martin Zwick

Complex Systems Faculty Publications and Presentations

This paper investigates how environmental structure, given the innate properties of a population, affects the degree to which this population can adapt to the environment. The model we explore involves simple agents in a 2-d world which can sense a local food distribution and, as specified by their genomes, move to a new location and ingest the food there. Adaptation in this model consists of improving the genomic sensorimotor mapping so as to maximally exploit the environmental resources. We vary environmental structure to see its specific effect on adaptive success. In our investigation, two properties of environmental structure, conditioned by …

A Proposed Method Of Transportation Feature Identification, J. Allison Butler, Kenneth Dueker

Center for Urban Studies Publications and Reports

Geographic information systems (GIS) are being increasingly deployed by transportation agencies to help them display, review, and utilize data. The primary items of interest are transportation facilities and services, which may take the form of highways, airports, bus routes, and seaports, among others. Using GIS software, transportation facilities are represented as geometric shapes; i.e., points, lines, and areas. However, it is increasingly apparent to GIS users in the field of transportation that a geometry-based approach is not sufficient.

The offered solution is to develop a feature-based GIS approach for transportation. The central requirement of such an approach is to have …

Adaptive Prefetching For Device-Independent File I/O, Dan Revel, Dylan Mcnamee, David Steere, Jonathan Walpole

Computer Science Faculty Publications and Presentations

Device independent I/O has been a holy grail to operating system designers since the early days of UNIX. Unfortunately, existing operating systems fall short of this goal for multimedia applications. Techniques such as caching and sequential read-ahead can help mask I/O latency in some cases, but in others they increase latency and add substantial jitter. Multimedia applications, such as video players, are sensitive to vagaries in performance since I/O latency and jitter affect the quality of presentation. Our solution uses adaptive prefetching to reduce both latency and jitter. Applications submit file access plans to the prefetcher, which then generates I/O …

Soil Moisture Gradients And Controls On A Southern Appalachian Hillslope From Drought Through Recharge, J. Alan Yeakley, W. T. Swank, L. W. Swift, G. M. Hornberger, H. H. Shugart

Environmental Science and Management Faculty Publications and Presentations

Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models, have been difficult to confirm empirically. While soil properties and topographic features are the two general physio-graphic factors controlling soil moisture on hillslopes, studies have shown conflicting results regarding which factor is more important. The relative importance of topographic and soil property controls was examined in an upland forested watershed at the Coweeta Hydrologic Laboratory in the southern Appalachian mountains. Soil moisture was measured along a hillslope transect with a mesic-to-xeric forest vegetation gradient over a period spanning precipitation extremes. The hillslope …

A Complex-Systems Perspective On The “Computation Vs. Dynamics” Debate In Cognitive Science, Melanie Mitchell

Computer Science Faculty Publications and Presentations

I review the purported opposition between computational and dynamical approaches in cognitive science. I argue that both computational and dynamical notions will be necessary for a full explanatory account of cognition, and give a perspective on how recent research in complex systems can lead to a much needed rapprochement between computational and dynamical styles of explanation.

Stackguard: Automatic Adaptive Detection And Prevention Of Buffer-Overflow Attacks, Crispin Cowan, Calton Pu, David Maier, Heather Hinton, Jonathan Walpole, Peat Bakke, Steve Beattie, Aaron Grier, Perry Wagle, Qian Zhang

Computer Science Faculty Publications and Presentations

This paper presents a systematic solution to the persistent problem of buffer overflow attacks. Buffer overflow attacks gained notoriety in 1988 as part of the Morris Worm incident on the Internet. While it is fairly simple to fix individual buffer overflow vulnerabilities, buffer overflow attacks continue to this day. Hundreds of attacks have been discovered, and while most of the obvious vulnerabilities have now been patched, more sophisticated buffer overflow attacks continue to emerge.

We describe StackGuard: a simple compiler technique that virtually eliminates buffer overflow vulnerabilities with only modest performance penalties. Privileged programs that are recompiled with the StackGuard …

Statistical Dynamics Of The Royal Road Genetic Algorithm, Erik Van Nimwegen, James P. Crutchfield, Melanie Mitchell

Computer Science Faculty Publications and Presentations

Metastability is a common phenomenon. Many evolutionary processes, both natural and artificial, alternate between periods of stasis and brief periods of rapid change in their behavior. In this paper an analytical model for the dynamics of a mutation-only genetic algorithm (GA) is introduced that identifies a new and general mechanism causing metastability in evolutionary dynamics. The GA’s population dynamics is described in terms of flows in the space of fitness distributions. The trajectories through fitness distribution space are derived in closed form in the limit of infinite populations. We then show how finite populations induce metastability, even in regions where …

Measurement Of The Focal Properties Of A Magnetic Electron Lens Using The Shadowgraph Method, Luis Thomas Almaraz

Dissertations and Theses

A method of experimentally determining the properties of a magnetic electron lens is presented. The method uses the shadows cast by two meshes, one placed in front of the lens and one behind the lens, to study the properties of the image of a point source. The lens properties are then calculated from the image properties. The paraxial values of focal length and focal distance as well as their spherical aberrations, are determined. The relationship between image and lens properties are discussed. The method is used here for the first time in determining the focal properties of a magnetic lens.

The Temperature Dependent Modification Of The Ca2+ Release Mechanism Of Skeletal Muscle Sarcoplasmic Reticulum, Shawn Patrick Mullen

Dissertations and Theses

The Ca²⁺ release protein/ryanodine receptor from skeletal muscle sarcoplasmic reticulum is shown to be modulated in a unique manner by small changes in temperature. Thiol oxidants and reducing agents modify channel function in a biphasic manner at 40° C, while at 34° C the channel exhibits only a monophasic behavior. Elevated temperature appears to expose a second set of reactive groups that, when either oxidized or reduced, alter function. Previous studies have focused on the properties of the release mechanism at or below 37° C. This study shows that at 40° C, which more reflects the body temperature of …

Faculty Senate Monthly Packet December 1997, Portland State University Faculty Senate

Faculty Senate Monthly Packets

The December 1997 Monthly packet includes the December agenda and appendices and the Faculty Senate minutes and attachments from the meeting held November 1997.

Flow And Congestion Control For Internet Streaming Applications, Shanwei Cen, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

The emergence of streaming multimedia players provides users with low latency audio and video content over the Internet. Providing high-quality, best-effort, real-time multimedia content requires adaptive delivery schemes that fairly share the available network bandwidth with reliable data protocols such as TCP. This paper proposes a new flow and congestion control scheme, SCP (Streaming Control Protocol) , for real-time streaming of continuous multimedia data across the Internet. The design of SCP arose from several years of experience in building and using adaptive real-time streaming video players. SCP addresses two issues associated with real-time streaming. First, it uses a congestion control …

Evaluation Of Accelerated Plethysmography As A Measure Of Health And Fitness, Angela Marie Humble

Dissertations and Theses

Plethysmography is a technique used for measuring alterations in the volume of organs or limbs. Japanese researchers have developed a relatively new application of plethysmography (accelerated plethysmography) that uses information from the pulse wave measured at the fingertip to make inferences about health and fitness status. The instrument used to collect data -- the Precaregraph (accelerated plethysmograph) -- provides an accelerated pulse waveform and APG index, a mathematical representation of the waveform. It was the purpose of this study to evaluate the validity of the Precaregraph by examining the relationship between the APG index and previously validated measures of health …

Molecular Fluorescence At A Rough Surface: The Orientation Effects, P.T. Leung, W. L. Blacke

Physics Faculty Publications and Presentations

The problem of the dynamical interaction between an emitting dipole and a metallic grating surface is considered with particular interest in the effects due to different orientations of the dipole with respect to the substrate surface. Our previous perturbative theory is extended to treat both parallel and perpendicular dipoles and the results are applied to the study of modified fluorescence characteristics for admolecules in the vicinity of a rough metal surface modeled as a grating. Numerical results show that some of the characteristics are very sensitive to the molecular orientation and the one along the grating direction is manifested with …

Materialized View Algorithms, Yubo Fan

Dissertations and Theses

A data warehouse is a stand-alone repository of integrated information available for decision support OLAP querying and analysis. Aggregate views can be materialized (stored in disk) to improve query performance in a data warehouse.

Several static and dynamic algorithms for selecting materialized aggregate views (MAV) in a data warehouse are proposed in this thesis. The algorithms are then compared by running a simulation system, which can be configured to compare several algorithms on different type of data warehouses. Simulation results for static algorithms are presented to show that several proposed algorithms perform close to an existing good algorithm (HRU Greedy) …

An Ice Shelf Mechanism For Heinrich Layer Production, Christina L. Hulbe

Geology Faculty Publications and Presentations

The effect of an ice shelf in the Labrador Sea on ice-rafted sediment delivery to the glacial North Atlantic is investigated using a finite element numerical model of ice shelf flow. Discharge into the shelf from Hudson Strait creates a thick central core, extending downstream into the shelf, that is flanked by relatively thin ice. Melting at the base of the deep keel would produce cool, fresh water which would rise to refreeze along the keel's flanks. Debris deposited by melting deep central ice could create the Heinrich layers observed in the Labrador Sea while the debris-rich ice protected by …

Geologic Evidence Of Historic And Prehistoric Tsunami Inundation At Seaside, Oregon, Brooke K. Fiedorowicz

Dissertations and Theses

Over the past decade, research conducted along the Cascadia subduction zone coast established evidence for coseismic subsidence, liquefaction, and nearfield tsunami deposition. Seaside is a low lying northern Oregon coastal city potentially at risk for nearfield tsunami inundation from a Cascadia earthquake. The 1964 Alaskan farfield tsunami impacted Seaside, and deposits from that event serve as a model for interpreting prehistoric tsunami deposits in the Seaside area. A reconnaissance subsurface study of potential tsunami inundation sites was performed by trenching and gouge coring in the coastal wetlands along the Necanicum River, Neacoxie Creek, drainage to the east of Neacoxie Creek, …

Complexity And Decomposability Of Relations, Martin Zwick

Complex Systems Faculty Publications and Presentations

A discrete multivariate relation, defined set-theoretically, is a subset of a cartesian product of sets which specify the possible values of a number of variables. Where three or more variables are involved, the highest order relation, namely the relation between all the variables, may or may not be decomposable without loss into sets of lower order relations which involve subsets of the variables. In a completely parallel manner, the highest order relation defined information-theoretically, namely the joint probability distribution involving all the variables, may or may not be decomposed without loss into lower-order distributions involving subsets of the variables. Decomposability …

Symmetry, Symmetry Breaking, And The Current View Of The Dirac Monopole, Erik Kristian Leder

Dissertations and Theses

The ideas of symmetry and symmetry breaking are considered in the context of classical gauge theory. Local U(l) symmetry is developed for a complex scalar field and electromagnetism is identified as the associated gauge field. Local S0(3) theory for a triplet of real scalar fields is derived and the incorporation of additional gauge fields is demonstrated. Symmetry breaking for the S0(3) gauge theory is performed and the gauge fields are shown to acquire mass by the Higgs mechanism. The equations of the t'Hooft-Polyakov monopole are derived and compared to those of the magnetic monopole of Dirac.

Modeling Improvements For Water Supply Forecasting In The Columbia River Basin, Daniel Albert Buller

Dissertations and Theses

The purposes of this study were twofold. The first was to explore possible improvements that could be made over existing methods by applying alternative modeling approaches, including the one developed by Garen to forecast runoff volumes in the Columbia River at The Dalles, Oregon. The second was to use the Southern Oscillation as one of the variables to forecast spring and summer runoff and to evaluate whether this variable adds significant information early in the season before any snow has accumulated. The Columbia River basin's mountainous topography and northern latitude are ideally suited for water supply forecasting because much of …

Cheetahs Are Fast, But Nearly Irrelevant, Calton Pu, Jonathan Walpole, Charles Consel

Computer Science Faculty Publications and Presentations

A brief paper submitted to the NSF Workshop on New Challenges and Directions for Systems Research, held in St. Louis, Mo., July 31-August 1, 1997. Outlines the case for more cooperation among software system architects, and a less reductionistic approach to software development.

Impedance Spectroscopy Of Bilayer Lipid Membranes And Tio₂ Based Solar Cells, Uwe Hermes

Dissertations and Theses

It has been proposed in the literature that a novel class of biosensors can be based on a bimolecular layer of lipids supported on one side by a metallic surface. In order to estimate the potential of this system for the design of membrane sensors, we have studied properties of a two-electrode system consisting of a teflon insulated metallic wire and a Ag/AgCl electrode, both immersed in KCl solution. The lipid bimolecular layer was formed on the metal surface of the cut teflon insulated wire. The electrical conductivity properties of such a device were studied in the frequency range 20 …

High-Performance Input/Output Circuit For Cmos Integrated Circuit Interface, Chee How Lim

Dissertations and Theses

In recent years, strong demand for high-performance electronic products has fueled the need for high-speed and high-integration VLSI circuits. This demand is expected to continue growing in the future, which will lead to development of IC's that are much more compact and operate at higher frequencies. As a result, preserving signal integrity for proper IC communications becomes an increasingly difficult challenge.

In this thesis, an understanding of IC noise in relation to IC packaging is sought. An IC package is modeled with sophisticated 3-D simulators to extract its corresponding parasitics. These parasitics, expressed in terms of resistance, inductance, and capacitance …