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Aku Newsletter : July 2001, Volume 1, Issue 6, Aga Khan University

The Aga Khan University Newsletters

No abstract provided.

Simulation Optimization Studies Of Routing And Process Flow Problems, Satish Ravichandran

Electrical & Computer Engineering Theses & Dissertations

Computer aided simulation is emerging as a powerful tool for numerical analysis and in conducting performance evaluations of complex systems that depend on a multitude of variables. The primary objective in such simulation studies is to gauge the performance of the system under a various constraints and operating conditions. The effects of changing the operating parameter space can thus be analyzed without having to implement costly changes. Simulations are also carried out for the baseline scenarios to verity and validate the basic underlying system model. In this thesis research, two practical problems were studied through numerical modeling, and optimized solutions …

Mantle Deformation Beneath Southern Africa, Paul G. Silver, Stephen S. Gao, Kelly H. Liu, Kaapvaal Seismic Group

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Seismic anisotropy from the southern African mantle has been inferred from shear-wave splitting measured at 79 sites of the Southern African Seismic Experiment. These data provide the most dramatic support to date that Archean mantle deformation is preserved as fossil mantle anisotropy. Fast polarization directions systematically follow the trend of Archean structures and splitting delay times exhibit geologic control. The most anisotropic regions are Late-Archean in age (Zimbabwe craton, Limpopo belt, western Kaapvaal craton), with delay times reduced dramatically in off-craton regions to the southwest and Early-Archean regions to the southeast. While thin lithosphere can account for weak off-craton splitting, …

Neural Network Approach To Causal Reasoning With Penalty Logic, Ghada Moussa Abdel Ghany Bahig

Archived Theses and Dissertations

No abstract provided.

The Effects Of Occupational Ultrasonic Noise Exposure On Hearing In Dental Hygienists: A Pilot Study, Jennifer S. Dunning

Dental Hygiene Theses & Dissertations

The purpose of this case-control study was to determine whether long-term ultrasonic noise exposure via the dental office environment is related to dental hygienists' hearing status. Registered dental hygienists (N = 698) who live in the Hampton Roads area were mailed a Dental Hygiene Work History Questionnaireto determine those meeting the inclusion criteria and willing to participate in the study. Consenting subjects were categorized into one of two groups according to ultrasonic scaler usage rate and matched on age. Persons with known hearing loss due to infection, disease, or congenital defect were excluded from the study. The final sample …

Trichodesmium Spp.: Numerical Studies Of Resource Competition, Carbohydrate Ballasting, And Remote-Sensing Reflectance, Tonya Denise Clayton

OES Theses and Dissertations

In recent years, a new appreciation for the role of diazotrophy in the oceans has emerged. This dissertation reports on three modeling studies designed to investigate ecological processes associated with Trichodesmium spp., the most conspicuous marine diazotroph: (1) characterization of a generalized model Trichodesmium and issues of macronutrient resource competition; (2) carbohydrate ballasting by Trchodesmium and implications for the formation of surface accumulations; and (3) the vertical distribution of Trichodesmium and implications for detection from space.

The first study focuses on issues of nitrogen and phosphorus competition and ecosystem structure. It utilizes a simple ecosystem model that includes dissolved nitrogen …

The Catalyst, July 2001, Illinois State University, Center For The Advancement Of Teaching

The CATalyst

Newsletter of the Center for the Advancement of Teaching (CAT) at Illinois State University

The Network Voice Summer, Man, Illinois Wesleyan University

Related Documents

No abstract provided.

Motorcycle Emissions System (Presentation), Donald H. Stedman

Fuel Efficiency Automobile Test Publications

Multireflection optics for noncontact measurement of small emissions plumes

On-Road Motor Vehicle Emissions Measurements Worldwide (Presentation), Sajal S. Pokharel, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

Separation Of Recollision Mechanisms In Nonsequential Strong Field Double Ionization Of Ar: The Role Of Excitation Tunneling, Bernold Feuerstein, Daniel Fischer, Alexander Dorn, Claus Dieter Schroter, J. Deipenwisch, Jose R. Crespo Lopez-Urrutia, C. Hohr, Paul B. Neumayer, Horst Rottke, Christoph Trump, M. Wittmann, Georg Korn, Wolfgang Sandner, Robert Moshammer, Joachim Hermann Ullrich

Physics Faculty Research & Creative Works

Vector momentum distributions of two electrons created in double ionization of Ar by 25 fs, 0.25PW/cm² laser pulses at 795 nm have been measured using a “reaction microscope.” At this intensity, where nonsequential ionization dominates, distinct correlation patterns are observed in the two-electron momentum distributions. A kinematical analysis of these spectra within the classical “recollision model” revealed an (e,2e)-like process and excitation with subsequent tunneling of the second electron as two different ionization mechanisms. This allows a qualitative separation of the two mechanisms demonstrating that excitation-tunneling is the dominant contribution to the total double ionization yield.

Resummation Of The Divergent Perturbation Series For A Hydrogen Atom In An Electric Field, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

We consider the resummation of the perturbation series describing the energy displacement of a hydrogenic bound state in an electric field (known as the Stark effect or the LoSurdo-Stark effect), which constitutes a divergent formal power series in the electric-field strength. The perturbation series exhibits a rich singularity structure in the Borel plane. Resummation methods are presented that appear to lead to consistent results even in problematic cases where isolated singularities or branch cuts are present on the positive and negative real axis in the Borel plane. Two resummation prescriptions are compared: (i) a variant of the Borel-Pad'e resummation method, …

Local Polariton Modes And Resonant Tunneling Of Electromagnetic Waves Through Periodic Bragg Multiple Quantum Well Structures, Lev I. Deych, Alexey Yamilov, Alexander A. Lisyansky

Physics Faculty Research & Creative Works

We study analytically defect polariton states in Bragg multiple quantum well structures and defect-induced changes in transmission and reflection spectra. Defect layers can differ from the host layers in three ways: exciton-light coupling strength, exciton resonance frequency, and interwell spacing. We show that a single defect leads to two local polariton modes in the photonic band gap. These modes cause peculiarities in reflection and transmission spectra. Each type of defect can be reproduced experimentally, and we show that each of these plays a distinct role in the optical properties of the system. For some defects, we predict a narrow transmission …

Gaussian Estimation Of Continuous Time Models Of The Short Term Interest Rate, Jun Yu, Peter C. B. Phillips

Research Collection School Of Economics

This paper proposes a Gaussian estimator for nonlinear continuous time models of the short term interest rate. The approach is based on a stopping time argument that produces a normalizing transformation facilitating the use of a Gaussian likelihood. A Monte Carlo study shows that the finite sample performance of the proposed procedure offers an improvement over the discrete approximation method proposed by Nowman (1997). An empirical application to U.S. and British interest rates is given.

Hydrographic Variability On Decadal And Interdecadal Scales In The Northern Gulf Of Alaska, Nandita Sarkar

OES Theses and Dissertations

The mixed layer depth (MLD) in the North Pacific is important to vertical mixing and hence the flux nutrients into the euphotic zone. A time series of hydrographic measurements, tem perature and salinity versus depth, at a coastal site in the northern Gulf of Alaska is used to determine the seasonal and interannual variations in the MLD. Data from this station called GAK 1 (59°50.7‘X. 149C28.0'\V) in 203 m of water begin in 1974 and end in 1998. The MLD changes seasonally from about 50 m in summer to more than 130 m in winter. These changes are in response …

Transverse Variability Of The Flow And Density In Inlets Of Southern Chile, Mario Arturo Cáceres Muñoz

OES Theses and Dissertations

Measurements of velocity and density profiles were made to describe the flow transverse structure in three inlets of southern Chile. The inlets show marked differences in their transverse dynamics in response to external forcing. In Aysen Fjord (45.2°S) the mean flow showed a three layer structure that was consistent with up-fjord wind-induced exchange, while in Chacao Channel (41.8°S), the mean flow exhibited predominantly a lateral structure that featured sharp velocity shears. In both cases, a bank in the center of the sections seemed to play an important role in shaping the mean flows. In Ventisquero Sound (44.4°S), the presence of …

Development Of Atlas Based Simulation Capability For Automated Testing, Rami Hanbali

Electrical & Computer Engineering Theses & Dissertations

Computer software is emerging as a powerful tool for controlling a large number of instruments and for the testing of these instruments. The main aim of this work is to provide a software program capable of controlling a large number of engineering instruments at the touch of a button. In addition, the software is to have the capability of connecting the instruments with the desired Unit Under Test. There is great need for such software driven testing in industry, especially for large complex systems. Advantages of such an approach include: (a) automated testing in a very quick and efficient manner; …

Optimal Aeroelastic Vehicle Sensor Placement For Root Migration Flight Control Applications, Abdul Ghafoor Al-Shenhabi

Mechanical & Aerospace Engineering Theses & Dissertations

An important step in control design for elastic systems is the determination of the number and location of control system components, namely sensors. The number and placement of sensors can be critical to the robust functioning of active control systems, especially when the system of interest is a large high-speed aeroelastic vehicle. The position of the sensors affects not only system stability, but also the performance of the closed-loop system. In this dissertation, a new approach for sensor placement in the integrated rigid and vibrational control of flexible aircraft structures is developed. Traditional rigid-body augmentation objectives are addressed indirectly through …

Illinois State: For Alumni Of Illinois State University, Summer 2001, Illinois State University, University Marketing And Communications

State: The Magazine of Illinois State University (1999-present)

Illinois State University alumni magazine

A Study On The Learning Styles Of Limited English Proficiency Students, Linda J. Clay

Masters Theses

Limited English Proficiency (LEP) students are not attaining academic success in public schools. Enrollment of Hspanic students is increasing, but at the same time assessment of their work shows little achievement. A crucial issue in the education of language minority students is how they learn. This thesis examines their learning style preferences through data gathered from student and teacher surveys and then correlates it to existing research. The conclusion drawn is that Hispanic LEP students are not being taught in their preferred learning styles and that the primary manner of verbal/linguistic instruction used in schools is a deterrent to successful …

Armstrong Academics Summer/Fall 2001, Armstrong Atlantic State University

Armstrong State University Collections: Armstrong Academics (Archived)

No abstract provided.

Pulsed Electron Heating Of Atmospheric Pressure Air Glow Discharges, Hisham Merhi

Electrical & Computer Engineering Theses & Dissertations

By applying electric field pulses of short duration (compared to the time constant for glow-to-arc transitions) to a weakly ionized gas, the electron energy distribution can be temporarily shifted to higher energies. This effect causes a nonlinear increase in the ionization rate and consequently a larger electron decay time. This effect has been demonstrated using single pulse operation.³ In order to generate plasma with semi-continuous electron density, repetitive operation is required. As a first step towards repetitive pulsed electric field operation, the temporal development of the voltage across the plasma for two subsequent pulses was measured. The dual pulse …

Minimum Mean Square Error Spectral Peak Envelope Estimation For Automatic Vowel Classification, Jaishree Venugopal

Electrical & Computer Engineering Theses & Dissertations

Spectral feature computations continue to be a very difficult problem for accurate machine recognition of speech. In this work, which focuses on vowels, a new spectral peak envelope method for vowel classification is developed, based on a missing frequency components model of speech recognition. According to the missing frequency components model, vowel recognition depends only on the spectral (harmonic) peaks. Smoothing and interpolation of the spectra, performed in the standard cepstral analysis method commonly used in automatic speech recognition, actually loses valuable information and results in reduced recognition accuracy. The new method for feature extraction presented in this thesis is …

Second Order Expansions For The Distribution Of The Maximum Likelihood Estimator Of The Fractional Difference Parameter, Offer Lieberman, Peter C.B. Phillips

Cowles Foundation Discussion Papers

The maximum likelihood estimator (MLE) of the fractional difference parameter in the Gaussian ARFIMA(0, d ,0) model is well known to be asymptotically N (0, 6/ π 2 ). This paper develops a second order asymptotic expansion to the distribution of this statistic. The correction term for the density is shown to be independent of d , so that the MLE is second order pivotal for d . This feature of the MLE is unusual, at least in time series contexts. Simulations show that the normal approximation is poor and that the expansions make significant improvements in accuracy.

Magnetic Properties And Nanostructures Of Composite, M.L. Yan, Yi Liu, M.J. Yu, Sy_Hwang Liou, David J. Sellmyer

Sy-Hwang Liou Publications

Nanocomposite Co_χPt100_100-χ :C thin films with χ = 57 and χ = 50 were prepared by magnetron sputtering. Structures and activation volumes were studied systematically in order to better understand the magnetic behavior.We found that activation volumes of these two samples were almost the same. However, physical grain sizes of these two samples were different. Magnetic grains in the sample with equiatomic Co and Pt composition were almost independently switched and magnetic grains in the sample with higher Co content were exchange coupled and switched together. The reduction of the physical grain size in the sample …

Grain-Boundary Micromagnetism, Ralph Skomski, H. Zeng, David J. Sellmyer

David Sellmyer Publications

Continuum and layer-resolved calculations are used to investigate the spin structure in the vicinity of grain boundaries. Reduced exchange in the grain-boundary region gives rise to a quasidiscontinuity of the magnetization and yields a perturbation which decays exponentially inside the grains. An effective intergranular exchange is obtained as a micromagnetically well-defined function of the grain-boundary exchange, and it is discussed how grain boundaries affect the hysteresis loops of nanostructures.

Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations With Weak Carbon Nucleophiles, M. Azad Hossain, Myung-Jong Jin, William A. Donaldson

Chemistry Faculty Research and Publications

The reaction of acyclic tricarbonyl(pentadienyl)iron(1+) cations with allyl trimethylsilane or with excess furan leads to (E,E-diene)iron complexes. Attack of these weak nucleophiles on the transoid form of the pentadienyl cation is presumably faster than attack on the more stable cisoid form.

Quorum Sensing In The Dimorphic Fungus Candida Albicans Is Mediated By Farnesol, Jacob M. Hornby, Ellen C. Jensen, Amber C. Lisec, Joseph J. Tasto, Brandon Jahnke, Richard Shoemaker, Patrick Dussault, Kenneth W. Nickerson

Patrick Dussault Publications

The inoculum size effect in the dimorphic fungus Candida albicans results from production of an extracellular quorum-sensing molecule (QSM). This molecule prevents mycelial development in both a growth morphology assay and a differentiation assay using three chemically distinct triggers for germ tube formation (GTF): L-proline, N-acetylglucosamine, and serum (either pig or fetal bovine). In all cases, the presence of QSM prevents the yeast-to-mycelium conversion, resulting in actively budding yeasts without influencing cellular growth rates. QSM exhibits general cross-reactivity within C. albicans in that supernatants from strain A72 are active on five other strains of C. albicans and vice versa. …

Managing Wolf Conflict With Livestock In The Northwestern United States, Ed Bangs, John A. Shivik

United States Department of Agriculture Wildlife Services: Staff Publications

Wolves (Canis lupus) were once common throughout North America but were deliberately exterminated in the lower 48 United States, except in northeastern Minnesota, primarily because of depredations on livestock. Wolves remained abundant in areas with few livestock such as most of Canada and Alaska. Sixty years after being nearly exterminated, the gray wolf was listed under the United States Endangered Species Act (Act) in 1974. The combination of natural recovery in NW Montana, and reintroduction in central Idaho and the Greater Yellowstone area (NW Wyoming, eastern Idaho, and SW Montana) has resulted in an expanding wolf population (Bangs …

Chemical Repellents And Other Aversive Strategies In Predation Management, J.R. R. Mason, J.A. Shivik, M.W. Fall

United States Department of Agriculture Wildlife Services: Staff Publications

Chemical repellents and other aversive strategies are the core of non-lethal wildlife management. These strategies typically depend on irritation (pain), conditioning, or fear for their effectiveness, and none is universally successful. Thus, conditioned food aversions deter browsing and foraging by deer (virginianus , O. hemionus), but are less useful with predators, because killing, not consumption, is the behavior of interest. Broadly speaking, the utility of non-lethal strategies is affected by number and density of wildlife species, availability of alternative foods, palatability and novelty of treated items, and intensity of pain, sickness, or fear used to establish avoidance. Some …