Digital Commons Network^™

Residence Time Of Groundwater Issuing From The South Rim Aquifer In The Eastern Grand Canyon, Jim Fitzgerald

UNLV Theses, Dissertations, Professional Papers, and Capstones

In the eastern Grand Canyon, secondary porosity created by north trending faults, folds, and breccia pipes, facilitates groundwater flow through the South Rim carbonate aquifer. Springs associated with the South Rim Aquifer have low ³H concentrations, [Ca²⁺]/[Mg²⁺] rations close to unity, and variable uranium concentrations. For a geochemical comparison, springs are subcategorized on the basis of geology and discharge. Type I springs are associated with high-angle normal faults and have high discharge rates. These springs discharge Ca²⁺ - Mg²⁺, HCO₃^- waters, have ³H concentrations <2 TR, and ²³⁴U/²³⁸U activity …

Trace Element Analysis Of Selected Springs In The Virgin River Basin, Mary A. Yelken

UNLV Theses, Dissertations, Professional Papers, and Capstones

Spring water from 23 springs in and near the Virgin River Basin (southwestern Utah, northwestern Arizona, and southeastern Nevada) was collected and analyzed for chemical concentrations. Trace elements and major ion chemistry was used to determine the potential for utilizing water chemistry to provide information on spring water source and flow pathways. Principal Component Analysis (PCA), rare earth element (REE) normalization patterns, and mineral equilibrium modeling (PHREEQE) techniques were used to analyze the data set. Four major spring water groups were displayed by the PCA, based on similarities in water chemistry. The analyses suggest that spring water chemistry is a …

Report Of Significant Findings--Las Vegas Bay/Boulder Basin Investigations, James F. Labounty, Michael Horn, Bureau Of Reclamation

Publications (WR)

Field sampling was carried out between 0830 and 1500 beginning at the confluence of Las Vegas Wash and the Inner Las Vegas Bay. Ten (10) locations were sampled, each in a similar manner. Locations of sampling stations are in line from the Wash-Bay confluence to a point midway between Saddle and Black Islands. In addition, sampling was done at a location midway between Sentinel Island and the base of Fortification Hill, and at the buoy line in front of Hoover Dam. Sampling stations are labeled from LV01, at Wash-Bay confluence, to LV17 at Hoover Dam. A significant data collection point …

Library Tech Notes, The Unlv Libraries Technology Committee

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Auger Resonant Raman Spectroscopy Used To Study The Angular Distributions Of The Xe 4d5/2 → 6p Decay Spectrum, B. Langer, N. Berrah, A. Farhat, Oliver Hemmers, J. Bozek

Environmental Studies Faculty Publications

The Auger resonant Raman effect can be used as a method to eliminate natural lifetime broadening in resonant Auger spectra. We have coupled this method with high-resolution photons from the Advanced Light Source to study angular distributions and decay rates of the Xe4d_5/2→6p resonant Auger lines. The angular distribution parameters β of almost all possible final ionic 5p⁴(³P, ¹D, ¹S)6p states have been determined. Our data, which remove the discrepancy between previous lower-resolution experimental results, are compared to different theoretical results.

Unlv Magazine, Barbara Cloud, Donna Mcaleer

UNLV Magazine

No abstract provided.

Innovations In Reuse, Lisa R. Osorio

UNLV Theses, Dissertations, Professional Papers, and Capstones

Material reuse benefits all sectors in the community by decreasing the amount of reusable solid waste that is discarded. It increases the resources available for various programs and builds partnerships with educators, and businesses to support and promote reuse programs that will improve the quality of life in areas in which they operate. Several areas of the country currently have reuse programs that focus on several areas of reuse. Successful projects in several cities have focused on such areas as reuse for education, the arts, or other nonprofit activities. These sustainable programs have benefited other communities and should serve as …

An Experimental Technique In Lowering Total Dissolved Solids In Wastewater, Aaron Crotts

UNLV Theses, Dissertations, Professional Papers, and Capstones

An experimental method for lowering total dissolved solids in wastewater. This thesis project has been undertaken by Aaron Crotts in partial fulfillment of requirements for the degree of Bachelor of Arts in Environmental Studies. The problem undertaken in this thesis is to apply an experimental technique in wastewater treatment in hopes of reducing the total dissolved solids. Total dissolved solids consist of various dissolved ions in water such as calcium, magnesium, sulfur and sodium. In looking at one industry in particular a local Ice Cream manufacture, the problem with total dissolved solids is evident because of their manufacturing process, an …

The Barriers Present In More Developed Countries And Less Developed Countries Slowing The Implementation Of Substainability, Luke Giovine

UNLV Theses, Dissertations, Professional Papers, and Capstones

In 1996 the natural resource base of the world is being depleted at a rate far below the sustainable level. This is very evident in less developed countries (IDC), where raw limited natural resources are being poorly utilized and/or exported to more developed countries (MDC). The More Developed Countries such as the United States, Japan, and Germany use a high amount of natural resources and energy to maintain their material Standard Of Living (SOL), and this is at rates above what their own country can sustain with its own natural resources within its own borders. Both MDC's and LDC's are …

An Analysis Of Remediation Alternatives In An Attempt To Establish An Effective Hydrocarbon-Contaminated Soils Remediation Program At The Yucca Mountain Site Characterization Project (Ymp), Marc A. Gonzales

UNLV Theses, Dissertations, Professional Papers, and Capstones

An analyses, of six (6) soil remediation alternatives was completed in attempt to establish an effective hydrocarbon-contaminated soils remediation program at the Yucca Mountain Site Characterization Program (YMP). The remediation alternatives analyzed included: no remediation, on-site incineration, off-site incineration, in-situ .bioremediation, ex-situ bioremediation, and excavation and disposal. Variables considered in the evaluation process included cost of contaminated soil transportation, treatment costs, future liability, and success of remediating the contaminated soils to below regulatory thresholds. The analysis concluded in the recommendation of an on-site ex-situ bioremediation treatment facility (BTF) to remediate hydrocarbon-contaminated soils at the YMP. The selection was based on …

Library Tech Notes, The Unlv Libraries Technology Committee

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A newsletter containing a variety of sections including:

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Accolades to Lamont!

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Networld+Interop 96 At the Las Vegas Convention Center

New CD-ROM and Electronic Products

Universal Access to E-Mail: Rand Corporation Study

Picture This...

Glossary

Standardizing Word Processing Software in the Library

Library Tech Notes, The Unlv Libraries Technology Committee

Library TechNotes

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Evapotranspiration From A Saltcedar-Dominated Desert Floodplain: A Scaling Approach, S. D. Smith, A. M. Sala, Dale A. Devitt

Life Sciences Faculty Research

The purpose of this study was to investigate evapotranspiration (ET) from a variety of scales (leaf to landscape) in saltcedar-dominated floodplain vegetation along the lower Virgin River of southern Nevada. Leaf-level gas exchange indicated that saltcedar exhibits similar stomatal conductance as the sympatric phreatophytes arrowweed, mesquite, and willow. However, sap flow in saltcedar was higher per unit sapwood area than the other species, suggesting that it maintains higher leaf area per unit sapwood area. At the stand level, saltcedar ET was found to exceed potential ET early in the summer when soils were moist and the water table was near …

Counseling And Testing For Hiv Prevention: Costs, Effects, And Cost-Effectiveness Of More Rapid Screening Tests, P. G. Farnham, Robin D. Gorsky, D. R. Holtgrave, Wanda K. Jones, Mary Guinan

School of Public Health Faculty Research

New rapid human immunodeficiency virus (HIV) antibody tests permit many individuals to receive test results and appropriate counseling at one clinic visit. Because currently used tests require significant time for processing, all individuals must return for a second visit for test results and counseling. Since return rates for the second visit are low, the more rapid tests present an opportunity to improve the efficiency of HIV counseling and testing.

The authors compared the costs and effectiveness of the currently used counseling and testing procedure and a streamlined procedure made possible by the new, more rapid screening tests. When test-positive clients …

Preventing Perinatal Transmission Of Hiv Costs And Effectiveness Of A Recommended Intervention, Robin D. Gorsky, P G. Farnham, Walter L. Straus, Blake Caldwell, D R. Holtgrave, R. J. Simonds, M F. Rogers, Mary Guinan

School of Public Health Faculty Research

In the United States, nearly all new human immunodeficiency virus (HIV) infections in children are acquired through perinatal (mother-to-infant) transmission. Each year, approximately 7000 infants are born to HIV-infected women in the United States.¹ Without intervention, an estimated 15-30% of these infants would become infected.² In 1994, results of the AIDS Clinical Trial Group (ACTG) Protocol 076 showed that treatment of infected pregnant women and their infants with zidovudine (ZDV) reduced the rate of perinatal HIV transmission from 25% to 8%.^3,4 Following these findings, the Public Health Service (PHS) issued recommendations for ZDV therapy to prevent perinatal …

Behavioral Science And Public Health: A Necessary Partnership For Hiv Prevention, Martin Fishbein, Mary Guinan

School of Public Health Faculty Research

We are now in the second decade of the AIDS epidemic in the United States. As of October 31, 1995, a total of 311,381 U.S. citizens had t died from AIDS, another 189,929 had been diagnosed with AIDS (1), and it is estimated that nearly l million persons are infected with HIV, the virus that causes AIDS (CDC). Despite the best efforts of biomedical researchers, we still have neither a cure nor a vaccine to prevent this deadly disease. Yet AIDS is a preventable disease; AIDS is first and foremost a consequence of behavior. It is not who you are, …

A Statistical Approach To Assess The Efficiency Of Bioremediation Methods, Cynthia Lynn Glickman

UNLV Retrospective Theses & Dissertations

There are a number of Superfund sites in which biotreatability studies are used to assess whether an addition of some surfactants have a positive effect on the rates of biodegradation of PAH concentrations when compared to a control. U.S. EPA, in many situations, will require a minimum of 40% reduction over the control before approving the bioremediation method. Typically, samples of PAH concentrations are collected from an experiment involving the bio-treatment and the control conditions. The percent reduction is calculated by the formula: {dollar}\rm{\=x\sb1-\=x\sb2\over x\sb1}\times100\%.{dollar}; If the above percent reduction exceeds 40%, then the biotreatment is considered to be effective. …

Predictor Of Ocr Accuracy Using Statistical Techniques, Juan Manuel Gonzalez

UNLV Retrospective Theses & Dissertations

Systems that predict optical character recognition (OCR) accuracy of an input image by a given OCR system were developed. Seven features associated with image defects were identified and utilized. Two kinds of nonparametric classification engines, the nearest neighbor rule-based and neural network-based, were implemented. The performance of these systems were compared to an old heuristic-based system using a cost model of a large-scale document conversion process and a test data set consisting of 502 pages. The results show that the performance of new classifiers were better than that of the heuristic-based system. The neural network-based system outperformed the nearest-neighbor-based system. …

Unlv Magazine, Barbara Cloud, Laurie Fruth

UNLV Magazine

No abstract provided.

Modeling International Tourism To Israel, Sharon Regev

UNLV Retrospective Theses & Dissertations

This research is based on a survey conducted by the Israeli Ministry of Tourism. Using econometric methods that allow inferences from the sample to a population that is not included in the sample, the following model was estimated. The model is based on two simultaneous decisions--the decision to visit Israel and the decision on how much money to spend on the visit. The estimates permit the computations to be made on the likelihood that a certain individual, from the general population, will choose to visit Israel; The main conclusion of this study is that the promotion of Israel in different …

Describing The Elephant: Multiple Perspectives In New York City's Watershed Protection Conflict, Krystyna Anne Stave

Public Policy and Leadership Faculty Research

New York City's efforts to avoid filtration mandated by the 1986 Safe Drinking Water Act Amendments and the 1989 Surface Water Treatment Rule have generated considerable controversy. Since the conflict began in 1990, a spectrum of stakeholder groups has emerged, representing land owners, sport fishermen, businesses, environmental groups, developers, and watershed communities. What was originally defined by New York City water supply managers as a scientific problem--identifying sources of water quality degradation and preventing contaminants from entering the water supply system--now has broadened to include a diverse set of social and economic issues as well.

Chattering Reduction And Error Convergence In The Sliding-Mode Control Of A Class Of Nonlinear Systems, Pushkin Kachroo, Masayoshi Tomizuka

Electrical & Computer Engineering Faculty Research

To reduce chattering in sliding-mode control, a boundary layer around the switching surface is used, and a continuous control is applied within the boundary. The effects of various control laws within the boundary layer on chattering and error convergence in different systems are studied. New functions for chattering reduction and error convergence inside the boundary layer are proposed which are discontinuous in magnitude but not in sign. The internal model principle has been used to generalize the design for the class of nonlinear systems being considered.

A Self-Consistent Numerical Method For Simulation Of Quantum Transport In High Electron Mobility Transistor; Part 1: The Boltzmann-Poisson-Schrodinger Solver, Rahim Khoie

Electrical & Computer Engineering Faculty Research

A self-consistent Boltzmann-Poisson-Schrödinger solver for High Electron Mobility Transistor is presented. The quantization of electrons in the quantum well normal to the heterojunction is taken into account by solving the two higher moments of Boltzmann equation along with the Schrödinger and Poisson equations, self-consistently. The Boltzmann transport equation in the form of a current continuity equation and an energy balance equation are solved to obtain the transient and steady-state transport behavior. The numerical instability problems associated with the simulator are presented, and the criteria for smooth convergence of the solutions are discussed. The current-voltage characteristics, transconductance, gate capacitance, and unity-gain …

Library Tech Notes, The Unlv Libraries Technology Committee

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The Long Journey: From Institutionalization To Adult Day Care, Kristin L Kampschroeder

UNLV Retrospective Theses & Dissertations

This thesis will present a field study of an adult day care center in an attempt to establish a new methodology which will address the different types of clients in the recent phenomenon of adult day care settings. Previous research and field study has only focused on adults within institutional settings or on the institutions themselves. Adult day care, on the other hand, has arisen as an alternate form of care which allows for greater flexibility and concern for clients' needs. This thesis, then, in differentiating adult day care from total institutions and in delineating the types of clients, will …

Multicasting In Generalized Class Networks, Carl Michael Lane

UNLV Retrospective Theses & Dissertations

A problem that we are experiencing in communication networks is the ability to efficiently multicast information to a group of network sites. Multicasting is defined as point to multipoint communications. Within a network, for example, we may want to send a message from one network site to five other network sites. This is an example of a multicasting operation; We are seeing an increased use of applications which blend not only data, but also voice, and video. Due to this increase in usage, we are experiencing a need to conserve network bandwidth and to avoid loading communication networks excessively. To …

Tunneling Phenomenon In Heterostructure Devices, Sreenivasulu V Maheshwarla

UNLV Retrospective Theses & Dissertations

A theoretical formulation for carrier current across hetero-interface in heterostructure semiconductor devices is presented using tunneling as the phenomenon. An analytical expression for the transmission coefficient as a function of energy using the Airy's function and exponential solutions to Schroedinger's equation for a linear potential variation is used in the calculations. This thesis addresses two theoretical problems: physics and modeling of gate current dependance on gate voltage in a heterostructure insulated gated field effect transistor (HIGFET) and, oscillations in the current-voltage characteristics of a double heterostructure bipolar transistor (DHBT); For HIGFETs, two components of tunneling currents, one from the decay …

A Methodology For Estimating Population For Transportation Risk Analysis, Marisa Guieb Mandocdoc

UNLV Retrospective Theses & Dissertations

In selecting a route for the shipment of hazardous materials, the primary public safety concern is that routing minimizes risk by avoiding populated areas while utilizing the shortest and safest possible routes to reduce time in-state shipments; This research presents a methodology for estimating population index which reflects density ranges for various population groupings. The population index is based on the number of tracts, tract density, and county density. The population index is initially defined for population {dollar}{dollar}8000. in the absence of more data to validate the results in the latter grouping, the index is redefined for population {dollar}<{dollar}2500 and population {dollar}\geq{dollar}2500. The index is used to determine the level of analysis required in evaluating population: county, tract, or block level; Routing analysis based on minimization of risk by minimizing affected population is performed for the state of Nevada. The analysis focuses on two alternative rail routes that are being considered by the Department of Energy (DOE) for the shipment of high level wastes and spent nuclear fuels. (Abstract shortened by UMI.).

Topics In Combinatorics: A Statistical Application, Susan Diane Mccuistion

UNLV Retrospective Theses & Dissertations

The discrete math area known as combinatorics has specific applications in statistics. In this paper, the relationship between combinatorics and statistics will be explored. Major areas of concentration will include: generating functions, special combinatorial numbers and their use in statistics, and the specific relationship of these functions and numbers to some of the more common discrete distributions found in statistics.

A Study Of Training Methodology For Customer Contact Employees In Spain, And Implications On Service Quality, Mireia Montane-Balague

UNLV Retrospective Theses & Dissertations

Studies on training for customer contact employees in the hotel industry have not been found in Spain. In the United States, ample research has been conducted in the areas of training, service quality, and customer satisfaction. However, studies on training programs for customer contact employees, and studies that address the influence of customer contact employees on customers' perceptions of quality are fairly This exploratory study was intended to evaluate the training methodology provided to customer contact employees in luxury properties in Spain, to assess perceptions of effectiveness of such training methods, and to relate such methodology to perceptions of service …