It is well known that the n-th eigenfunction to one-dimensional Sturm-Liouville eigenvalue problems has exactly n-1 nodes, i.e. non-degenerate zeros. For higher dimensions, it is much more complicated to obtain general statements on the zeros of eigenfunctions. The author states a new conjecture on the number of nodal domains of spherical harmonics, i.e. of connected components of S^2 \ N(u) with the nodal set N(u) = (x in S^2 : u(x) = 0) of the eigenfunction u, and proves it for the first six e...

This paper uses a dataset of first-time students in Austria, which shows among other information the home location and the university location of those students. Since Austria has a free access university system, where universities have to accept high school graduates, these data reflect the preferences of these students. From a university’s point of view, the data reflect the area from where they can attract students, i.e. the market areas of the universities. Currently, the market are...

In this paper we show that the well­known asymptotic efficiency bounds for full mixture models remain valid if individual sequences of nuisance parameters are considered. This is made precise both for some classes of random (i.i.d.) and non­random nuisance parameters. For the random case it is shown that superefficiency of the kind given by an example of Pfanzagl (1993) can happen only with low probability. The non-random case deals with permutation invariant estimators under o...

Forestry

This dissertation examines four issues, including: (a) whether outdoor recreation experiences not included inthe Recreation Experience Preference (REP) scales exist; (b) whether these experiences can be categorizedusing a framework called the Recreation Experience Matrix (REM); (c) how well the Recreation OpportunitySpectrum (ROS) variables of activity, setting, and expertise explain the types of experiences outdoorrecreationists receive; and (d) how well two new variables--primary mode and mode...

Adult Education

This study assessed the changing mission of the Industrial College of the Armed Forces as it evolved from the institution s founding as the Army Industrial College in 1924 to its 70th anniversary in 1994. The study drew heavily from archival materials in the Special Collections of the National Defense University in Washington, DC.The problem investigated in this research was to analyze how and why the institution s mission changed over time within the context of internal and external forces and ...

Architecture

This thesis is an attempt to reconcile the form of an idea with the form of athing in this world to be experienced. An exploration of the meaning behindthe words idea, form, making and experience begins to unite the intellect ofan architect with the design of an architect. The terms are defined in thethesis and explained through the project. The thesis through the projectsets out to take these terms beyond mere words and give them anopportunity to inform eachother. It is this dialectic between i...

Entomology

I have worked on a Case-Based Reasoning(CBR) system that evaluates crop rotations fortheir soil erosion and risk of insect pestproblems. The purpose of this system is toprovide decision support for an automatedwhole-farm planner (CROPS). CROPS (Buicket al., 1992) generates crop rotation plans thatcan address some of the environmental,economic and legislative pressures facing naturalresource managers. To generate andrecommend a crop rotation plan CROPSrequires estimates on the soil erosion risks ...

Electrical and Computer Engineering

In the past, various approaches to the highperformance numerical computing problem havebeen explored. Recently, researchers havebegun to explore the possibilities of using FieldProgrammable Gate Arrays (FPGAs) to solvenumerically intensive problems. FPGAs offer thepossibility of customization to any givenapplication, while not sacrificing applicability toa wide problem domain. Further, theimplementation of data flow graphs directly insilicon makes FPGAs very attractive for thesetypes of problems...

Family and Child Development

Parents with adolescents often find themselves caught in the stress and strain that normally accompanies thisstage of life. It is when parents cannot meet the demands of troubled adolescents that they find themselvesseeking family therapy. Most of what is reported about the process of therapy continues to be from thetherapist s or reseacher s perspective. There has been an increased interest in what clients have to say abouttheir experiences. The purpose of this study was to develop a detailed d...

Mathematics

Fertilized frog eggs (and cell-free extracts)undergo periodic oscillations in the activity of"M-phase promoting factor" (MPF), thecrucial triggering enzyme for mitosis (nucleardivision) and cell division. MPF activity isregulated by a complex network ofbiochemical reactions. Novak and Tyson, andtheir collaborators, have been studying thequalitative and quantitative properties of a largesystem of nonlinear ordinary differentialequations that describe the molecular details ofthis system ...

Management

By combining normative philosophy and empirical social science, I craft a research framework for assessingdifferential expectations of economic justice within the economic social contract of the United States. I arguethat distinct viewsof such a contract grounded in the tradition of individualism and communitarianismmanifest in people s judgments about economic justice. We empirically test these hypotheses on a sample of270 subjects, finding broad support for the theoretical framework.

Family and Child Development

The purpose of this study was to examine privilege in families and uncover the complexities of siblingrelationships in adulthood. Through interviewing 13 adult siblings and 3 mothers from 4 families my goalwas to gain a clearer picture of what privilege in families means. The sample consisted of a family with 3sisters, a family with 3 brothers and a sister, a family with 4 brothers, and a family with 2 brothers and asister. The adult siblings ranged in age from 30 to 60, with an average age of 4...

Animal and Poultry Sciences

An expert system to predict the fertility of beef heifers was developed using the A.I. Toolkit KAPPA-PC2.33. The knowledge base was developed from scientific literature and from a beef cattle reproductionexpert. The expert system computes an evaluation age, age both at the start and end of the breeding season,and weight per day of age to classify a heifer as having either a 3LOW2, 3GOOD2, or 3EXCELLENT2likelihood of conception. The expert system summarizes the information that is entered into th...

Biological Systems Engineering

A probabilistic risk assessment (PRA) for the discharge of excessive nitrogen from nonpoint sources (NPSs) to a stream was performed for a small agricultural watershed in northern Virginia. Risk, by definition, is the product of the frequency of occurrence of an event and the consequences of that event. The purpose of this research was to determine theprobability of occurrence of a nitrogen discharge event (i.e., frequency). The consequences of such a discharge event were not explicitly determin...

Biological Systems Engineering

Continuing development of the Virginia Tech campus is increasing downstream flooding and water quality problems. To address these problems, the University has proposed the construction of a stormwater management facility to control the quantity and quality of stormwater releases to Strouble Creek, a tributary of the New River.The overall goal of this project is to design a stormwater management facility proposed for the Virginia-Maryland College of Veterinary Medicine at Virginia Tech in Blacksb...

Hospitality and Tourism Management

Among the 44000-plus general managersemployed in United States hotels in 1993,there were only 100 women, 15African-Americans, and threeAfrican-American women. Additionally, lessthan 0.5 percent of corporate hospitalitymanagers were women. Given this relativeunderrepresentation of European-Americanwomen and African-Americans, combinedwith the increasing diversity of hotel clienteleand service providers, the purpose of thisstudy is to broaden our understanding of thesources of inequitable occupati...

Human Nutrition, Foods, and Exercise

Two experiments were conducted to examine the effects of type of milk (whole; nonfat; nonfat, 70%lactose-reduced) and type of egg (fresh, whole egg; egg substitute) on the quality of baked custards. The eggsubstitute was a combination of dried egg whit e solids, dried low-fat, low-cholesterol egg yolk solids, andxanthan gum. Custard formulations served as prototypes for use in studies conducted in the Department ofFood Science and Technology, Virginia Tech. In those studies, the effects of proce...

Industrial and Systems Engineering

Recent technological innovations and the need for increasedsafety on the world s roads have led to the introduction of In-Vehicle Information Systems (IVIS). These systems will providenavigation and advisory information to drivers while they aredriving. One aspect of these systems, In-vehicle SigningInformation Systems (ISIS), would provide the warning, regulatory,and advisory information that is currently found on road signs.These systems may be of particular benefit when external elementssuch ...

Family and Child Development

A qualitative study on a sample of 12 Puerto Rican women was conducted inPuerto Rico. The purpose of this study was to explore the various ways in whichsexual meanings are created, changed, and modified as the nature of socialdiscourse and personal experience changes. The two theoretical frameworks thatguided the methodology and analysis of the data were social constructionism andfeminism. I assumed that sexuality is socially constructed, shaped by social,political, and economic influences, and ...

Mathematics

Superconductivity continues to be of greattheoretical and practical interest and remains achallenging area of scientific inquiry. Mostsuperconductors of practical utility are oftype-II, i.e., they allow the penetration ofmagnetic fields in the form of tubes of flux thatare referred to as ``vortices. Motion of thesevortices due to, e.g., applied currents, induce aloss of perfect conductivity. Knowing howvortices move and arrange themselves in latticestructures, how their movement is suppressedby ...

Plant Pathology, Physiology, and Weed Science

The rate limiting step in isoprenoidbiosynthesis is catalyzed by3-hydroxy-3-methylglutaryl CoA reductase(HMGR, EC 1.1.1.34). In plants, HMGR isencoded by small gene families whosemembers are differentially expressed. Intomato, hmg2 was previously isolated andsequenced. We report the isolation andsequence analysis of a clone (pCD4)encompassing exon I of tomato hmg1 whichencodes the putative membrane domain.Sequence comparisons of plant HMGRproteins reveal two hydrophobic stretcheswithin the amino...

Plant Pathology, Physiology, and Weed Science

The objectives of this study were todetermine the effects the temperaturesensitivity of alleles of Rsv1 in soybean(Glycine max (L.) Merr.). Soybean cultivarscarrying alleles of Rsv1 were exposed toseveral heat treatments designed to induceheat shock protein production prior toinoculation with soybean mosaic virus(SMV). The heat treatment methods weresimilar to those employed in the research withN gene-tobacco mosaic virus studies. Thesoybean cultivars used were Lee 69, York,Kwanggyo, Ogden and P...

Science and Technology Studies

This social history of science policy development emphasizes the impact on the agricultural community of federal policies regarding release of recombinant DNA (rDNA) organisms into the environment. The history also demonstrates that the U.S. Coordinated Framework for Biotechnology Regulation (1986) is based principally in political criteria, not solidly based in science as its proponents claimed. The power struggle among policy negotiators with incompatible belief systems resulted in a political...

Counselor Education

This study was designed to investigate aphenomenon, persistence of undergraduatewomen in their engineering majors, from aqualitative paradigm. Guided by the tenets offeminist and inclusive research, the assumptionwas made that all women, whether they persistor not in their engineering majors, havestrengths and insights into their own personalexperiences. The experiences of AfricanAmerican women, Asian women, Caucasianwomen, Hispanic women, women from ruralgeographical areas, and non-persisters w...

Mechanical Engineering

Two aspects of the study of the Earth radiation budgetand the effects of clouds on our climate system areconsidered in this dissertation: instrumentation anddata interpretation. Numerical models have beendeveloped to characterize the optical/thermal-radiativebehavior, the dynamic electrothermal response andthe structural thermal transients of radiometricchannels. These models, applied to a satellite-bornescanning radiometer, are used to determine theinstrument point spread function and the poten...

Biology

In this study, features of ecology, behavior, andfunctional morphology related to feeding activity oftwo populations of the amphipod Gammarus minuswere compared. The two populations occupieddifferent habitats, and I attempted to determinewhether differences observed between the twopopulations were related to habitat. Annualproduction and life history of the populations werecompared and their relationship to factors such astemperature, water-chemistry, and quantity ofavailable organic matter were...

Architecture

Three houses are sited in the New River Valley ofSouthwestern Virginia in 1996. Each house is designed toprovide the essential utilitarian resources necessary forhabitation in modern Appalachia. The relative context withinwhich to make each house has been found within the uniquecharacter of the individual sites. Each house exists within thecurrent moment and place, so they therefore associate with amodern version of the Appalachian material palette: milledlumber, concrete and concrete block, raw...

Forestry

Geographic information systems ( GIS ) are aneffective tool for land management. Bystudying the land formations and land cover ofa site, much information about the tree andanimal species inhabiting a site can beestimated. The managers of public or privatelands may find the concept of a multi-layeranalysis of their land useful in discriminatinglocations based on their many characteristics. Icreated a database of a small area with nopreviously specified objective. I produced agroup of map layers e...

Architecture

In order to understand a sentence fully, onemust understand its parts and the way theywork. A complete sentence, in its most simpleform, is a substantive with a verb in agreement.Additions to this sentence may include othersubstantives and verbs, but most additions aremodifiers, either adjectival or adverbial. Thesemodifiers should enhance the substantive andits verb, elevating their existence within thesentence. However, modifiers may also detractfrom the substantive and verb. This occurswhen t...

Civil Engineering

The I-81 Corridor in Virginia traverses the westernpart of the state, connecting Bristol in the southto Winchester in the north. A study carried out atthe Virginia Tech Center for Transportation Researchidentified traffic safety, work zone safety and trafficcontrol, trucking issues, and intercity travelerinformation needs as important issues that deserveattention on the I-81 Corridor in Virginia. Analysisof work zone accident statistics showed a need forreal-time systems to enhance work zone saf...

Electrical and Computer Engineering

A constantswitching frequency with the sixth-order harmonicinjection PWM concept is established, and asixth-order harmonic injection technique isdeveloped for the harmonic reduction of asingle-switch three-phase boost rectifier. Theapproach employs a constant duty cycle withsixth-order harmonic injection to suppress thedominant (fifth-order) harmonic in the inputcurrents. Hence, to meet the THD<10%requirement, the rectifier voltage gain can bedesigned down to 1.45; to meet the IEC1000-3-2...

Large Animal Clinical Sciences

Records of bovine samplessubmitted for salmonella cultures atfour regional diagnostic laboratoriesin the state of Virginia were used toinvestigate the association of weatherconditions and the diagnosis ofsalmonellosis in cattle. Spearman¹scorrelation coefficients werecalculated for the correlationsbetween the monthly number ofsamples positive for salmonellaculture and weather parameters:temperature, precipitation, andrelative humidity. Significantcorrelation coefficients between themont...

Civil Engineering

The purpose of this study is to investigate spatial wood structures, trace their response on equilibrium paths, identify failure modes, and predict the ultimate load. The finite element models of this study are based on the Crafts Pavilion dome (Triax) in Raleigh, North Carolina, and the Church of the Nazarene dome (Varax) in Corvallis, Oregon. Modeling considerations include 3-d beam finite elements, transverse isotropy, torsional warping, beam-decking connectors, beam-beam connectors, geometri...

Plant Pathology, Physiology, and Weed Science

Isoxaben is a preemergence herbicide used for broadleaf weed control in turf and ornamentals. Although isoxaben can be used on a number of ornamentals, certain species are injured by isoxaben applications. The objectives of this research were: a) to evaluate the tolerance of ajuga, wintercreeper and dwarf burning bush to isoxaben applications, b) to compare the absorption, translocation and metabolism of isoxaben following root and shoot application in these ornamentals, and c) to examine the ef...

Electrical and Computer Engineering

This research investigates robust demodulationof Gaussian Minimum Shift Keying (GMSK)signals, using demodulator diversity andreal-time bit-error-rate (BER) estimation.GMSK is particularly important because of itsuse in prominent wireless standards around theworld (GSM, DECT, CDPD, DCS1800, andPCS1900). The dissertation begins with aliterature review of GMSK demodulationtechniques (coherent and noncoherent) andincludes an overview of single-channelinterference rejection techniques in digitalwirel...

Chemistry

Nitrile containing siloxane block copolymerswere developed as stabilizers for siloxanemagnetic fluids. The siloxane magnetic fluidshave been recently proposed as internaltamponades for retinal detachment surgery.PDMS-b-PCPMS-b-PDMSs (PDMS =polydimethylsiloxane, PCPMS =poly(3-cyanopropylmethylsiloxane) weresuccessfully prepared through kineticallycontrolled polymerization ofhexamethylcyclotrisiloxane initiated by lithiumsilanolate endcapped PCPMS macroinitiators.The macroinitiators were prepared ...

Mining and Minerals Engineering

When a large area of open gob collapsessuddenly, a windblast is produced that cancause considerable damage throughout theinfrastructure of a mine. In a few cases, thewindblast has been accompanied by ignitionsof methane and/or coal dust. Analytical andnumerical analyses investigated the transientbehavior of the air through the small timeperiod during which the roof is falling. This issufficiently short to allow adiabaticcompression of the air, i.e. negligible heattransfer to rock surfaces. Contr...

Teaching and Learning

Visual learning experiences are becomingincreasingly prevalent in education as symbols,imagery and simulations replace traditionaltext-based materials. Although the utilization ofimages for instructional purposes is not a newoccurrence, most images used in instructionhave been two-dimensional representations,giving learners little experience working withthree-dimensional images. Little research hasbeen done to explain the effects oftwo-dimensional and three-dimensional stimulion the learning pro...

Vocational and Technical Education

The purpose of this study was to examine(a) the ways in which employed feminist mothers ofadolescent daughters share information about the worldof work, and (b) how daughters are influenced by thecommunication they have with their mothers about careers.The research was conducted in a series of qualitativeinterviews with eight mother-daughter dyads and twomother-daughter triads. The mothers and adolescentdaughters lived in one of two communities in theSoutheastern United States. Mothers and daugh...

Industrial and Systems Engineering

This study evaluated the usefulness of a psychophysical model as part of a new ANSI/HFES 100 standard for CRT flicker. A graph based flicker prediction method developed from Farrell, 1987 was evaluated. The Farrell model is based on phosphor persistence, screen luminance, display size, and viewing distance. The graph based method assumes a worse case scenario (i.e. a white display screen shown on a display with P4 phosphor). While the Farrell model requires photometric measurements to be taken u...

Architecture

Puerto Rico is a place of strong sunlight, temperate windsand humid climate. It is also a place where the landscapeand the natives are very colorful. Today s culture consists ofa chaotic urban atmosphere which tends to obscure anextraordinary geography and the natural richness of itssurroundings. As in any Western metropolitan area, urbanlife demands its toll. San Juan is plagued by noise, and heatintensifies between its buildings. Modern air-conditioning isby now a part of every work place and ...

Philosophy

Traditionally, John Stuart Mill has beendescribed as a transitional thinker who fails tofully understand the values he espouses.Critics contend that he cannot simultaneouslyespouse both utility maximization and theprotection of individual choice-making as anon-trumpable value. Like his moralphilosophy, Mills political thought is alsorejected for interspersing, seemingly atrandom, elements of utilitarianism withconcerns about respecting individualchoice-making. More recent attempts tobring Mills ...

Materials Science and Engineering

Ordered intermetallics based on transitionmetal aluminides have been proposed asstructural materials for advanced aerospaceapplications. The development of thesematerials, which have the advantages of lowdensity and high operating temperatures, havebeen focused on the aluminides of titanium,nickel and iron. Though these materials exhibitattractive properties at elevated temperatures,their utilization is limited due to theirpropensity for low temperature fracture andsusceptibility to decreased du...

Educational Leadership and Policy Studies

The purpose of this study was to explorehow students manage their financialresources. Data consisted of student recordsof their expenditures and income over a onemonth period of time, reliable financialdocuments provided by the respondents (i.e.,checkbook registers, credit cardstatements), and individual interviews.This study was designed to gain a betterunderstanding of the financial behaviors ofcollege students at a large, public, researchuniversity. Specifically, this study wasdesigned to exp...

Physics

Results are presented for a unified analysisof the reactions pp -> pp. pid -> pid andpid -> pp over the center-of-mass energyinterval from pion threshold toapproximately 2.4 GeV. These results forpid -> pp and pid elastic scattering aresuperior to previous VPI analyses of thesereactions. In particular, the overall phase inpid -> pp has now been determined.Comparisons and predictions are made withprevious (separate and unified) analyses ofthis two-baryon system....

Industrial and Systems Engineering

As the focus of this research, a newmethodology -- human PerformanceAssessment Methodology (PAM), isintroduced. PAM provides a quantitativebasis for evaluating display image qualitybased on the visual events that occur in atask. The PAM approach identifies thevisual events, decisions, and actions for adisplay system. To support PAM, atheoretical model, the Model of VisualEvents (MOVE), is proposed for describingthe relationship between visual events,decisions, and actions. MOVE describesfour cat...

Engineering Science and Mechanics

The damage development and strength ofply-level scaled carbon/epoxy compositelaminates having stacking sequence of[+Tn/-Tn/902n]s where constraint ply angle, T,was 0, 15, 30, 45, 60, and 75 degrees, andsize was scaled as n=1,2,3, and 4, is reportedin Part I. X-radiography was used to monitordamage developments. First-ply failure stress,and tensile strength were recorded. First-plyfailure of the midplane 90 deg. plies dependedon the stiffness of constraint plies, and size. All24 cases were predic...

Chemistry

Inorganic-organic hybrid materials have been developed using sol-gel reactions of atrialkoxysilylated organic compound and a metal or semi-metal alkoxide and applied as coatingson polymeric or metallic substrates. Many of these coatings have demonstrated good to excellentabrasion resistance.Abrasion resistant coatings were prepared by hydrolysis and condensation of mixtures ofa triethoxysilylated diethylenetriamine (f-DETA), tetramethoxysilane (TMOS), water and analcohol in the presence of an ac...

Plant Pathology, Physiology, and Weed Science

In the U.S., soybean mosaic virus(SMV) is classified into seven straingroups, designated G1 to G7, basedon their different responses on resistantsoybean [Glycine max (L.) Merr.]cultivars. These responses are:symptomless or resistant (R), necrotic(N), and mosaic or susceptible (S).The gene-for-gene model has beenproposed for SMV-soybeaninteractions. In the majority of cultivars,a single dominant gene, Rsv1, confersboth the R and N responses. In the firstpart of this study, the coat protein (CP)ge...

Engineering Science and Mechanics

The initiation and propagation ofadiabatic shear bands is analyzednumerically for an impulsively loadedthick-walled steel tube. Acircumferential V-notch located at theouter surface of the center of the tubeprovides a stress concentration. Thematerial is modeled as strain hardening,strain-rate hardening and thermalsoftening. The dynamic loadingconditions considered are pure torsion,axial pressure combined with torsion,and internal pressure combined withtorsion. Because of the stressconcentration,...