Physical Sciences and Mathematics Commons^™

Optimal Control Applied To A Discrete Time Influenza Model, Paula Andrea Gonzalez Parra

Open Access Theses & Dissertations

For the last decades, mathematical epidemiological models have been used to understand the dynamics of infectious diseases and guide public health policy.

In particular, several continuous models have been considered to study influenza outbreaks and their controls policies. However, most epidemiological data is discrete; therefore, a discrete formulation is more convenient to compare collected data with the output of the model. We introduce a discrete time model in order to study optimal control strategies for influenza transmission.

In our model, we divide the population into four classes: susceptible, infectious, treated, and recovered individuals.

In particular, we evaluate the potential effect …

Development Of An Expert System To Aid In The Selection Of Sustainability Design Engineering Methods, Pedro Renato Acosta

Open Access Theses & Dissertations

The objective of this thesis is to present the development of an expert system to aid designers in the selection of design methods, in particular for sustainability methods. When practicing engineers need help in their design process, they look for design methods and tools; this is a challenge especially for inexperienced engineers in the sustainability area. Engineers, due to time constrains, will only utilize one or few methods during their professional life. The origin of this situation can be traced to engineering education, where it is typical that an instructor prefers one or few methods in particular, and even when …

Development And Testing Of An Unmanned Aircraft System For Environmental Science, Jerald James Brady

Open Access Theses & Dissertations

For some environmental science applications, Unmanned Aircraft Systems (UASs) are increasingly recognized for their capacity to collect remotely sensed data in a safer, more efficient and effective manner than is permitted with manned aircraft and satellite remote sensing platforms. To date, however, technological, human, and other challenges have constrained adoption of UASs in the environmental sciences. This study developed and tested a new UAS for an archetypical environmental science research group (stakeholder) composed of non-UAS experts. Specifically, this thesis: 1) Assessed the research and operational needs of the stakeholder to determine the optimum UAS platform; 2) Developed an Unmanned Aerial …

Decentralized Fault Tolerant Caching With Memcached, Bivas Das

Open Access Theses & Dissertations

Recent changes in web trends not only have increased popularity of web services, but also have vastly increased usage. Popular techniques, such as web-caching, used by content and service providers to provide faster content delivery at user end, is not enough to keep up, due to diversity and dynamic nature of web-contents.

Emerging ideas to cache on the server side, for faster content generation and delivery, is currently in use by popular web-service providers. One example of such caching system is Memcached. However, memcached, a distributed high performance caching system, is ineective in dynamic organization of itself and scaling when …

Photocatalytic Destruction Of Halogenated Organic Compounds In Water With A New Photocatalyst, Mabruka Hadidan

Open Access Theses & Dissertations

In this research, a newly developed high surface area semiconductor porous material was synthesized from potassium titanium niobium mixed oxide (KTiNbO5) to be used as a photo catalyst in the presence of UV light to degrade halogenated organic compounds in water. The goal of the project was to investigate the catalytic activity of the material for its effectiveness in the degradation of the halogenated organic compounds, and it is the first investigation of this new photocatalyst with halogenated compounds. Model compounds dichloromethane, 1-chlorobutane, chlorobenzene, and trifluoroacetic acid in aqueous solutions were tested with the photocatalyst under ultraviolet light irradiation, using …

A Framework For Strategic Sustainable Supply Chain Design, Abril Paola Vazquez

Open Access Theses & Dissertations

Sustainable supply chain management has raised interest considerably in recent years; due to environmental concerns from society as well industries. There is a high interest in the industries to solve this problem but many of the frameworks are directed to specific situation or structure. A strategic sustainable supply chain design framework is presented with the purpose of providing many companies, including small and big industries, the means to maintain an eco-friendly operation. These include; industry plants, distribution centers, and retailers.

Development Of A Web-Based Geographic Information System For Arctic Science, George Walker Johnson

Open Access Theses & Dissertations

Environmental science is a large field of study that requires the acquisition of data for decision making in solving environmental issues. Leveraging desktop geographic information systems (GIS) and web-based GIS (WebGIS) systems for assisting in the problem solving processes can benefit both the research community and policy makers for decision making activities. Ensuring interoperability between desktop, web, and server GIS is essential for maximizing access, sharing and manipulation of data. Interoperability is maximized through the adoption of best practices, use of open standards, and utilization of Spatial Data Infrastructures (SDI). While many of the interoperability challenges such as infrastructure, data …

On Constrained Optimization Schemes For Joint Inversion Of Geophysical Datasets, Uram Anibal Sosa Aguirre

Open Access Theses & Dissertations

In the area of geological sciences, there exist several experimental techniques used to advance in the understanding of the Earth. We implement a joint inversion least-squares (LSQ) algorithm to characterize one dimensional Earth's structure by using seismic shear wave velocities as a model parameter. We use two geophysical datasets sensitive to shear velocities, namely Receiver Function and Surface Wave dispersion velocity observations, with a choice of an optimization method: Truncated Singular Value Decomposition (TSVD) or Primal-Dual Interior-Point (PDIP). The TSVD and the PDIP methods solve a regularized unconstrained and a constrained minimization problem, respectively. Both techniques include bounds into the …

Specification Of Data Properties To Identify Anomalies In Scientific Sensor Data, Irbis Gallegos

Open Access Theses & Dissertations

Environmental scientists use advanced sensor technology such as meteorological towers, wireless sensor networks and robotic trams equipped with sensors to perform data collection at remote research sites. Because the amount of environmental sensor data acquired by such instruments is increasing, the ability to evaluate the accuracy of the data at collection time and to check that the instrumentation is operating correctly become critical in order to not lose valuable time and information. The goal of the research is to define a solution, based on software-engineering techniques, to support the scientist's ability to specify data properties that can identify anomalies in …

Development Of A Low-Cost Network Of Webcams For Monitoring Plant Phenology In A Chihuahuan Desert Shrubland, Libia Gonzalez

Open Access Theses & Dissertations

Phenology is the study of the timing of natural events such as the schedule of plant life-cycle events like bud burst, flowering, seed set and senescence. Many factors control plant phenological dynamics including climate. As such, phenology has been shown in published literature to be one of the best biological indicators of climate variability and change. Recent advantages in digital photography and digital image processing have opened new opportunities for inexpensive, repeatable and automated capture of plant and landscape phenological dynamics. This technology, however, remains poorly studied in terms of its capacity to depict the development of different plant phenophases, …

Gemini Metallo-Surfactants: Chemical And Physical Properties, Erich Ivan Valenzuela

Open Access Theses & Dissertations

Gemini surfactants are amphiphilic molecules that consist of two surfactant molecules chemically joined together by a spacer group. These molecules tend to self‐assemble into vesicles at much lower concentrations than traditional surfactants and have found many applications in catalysis, adsorption applications, drug‐delivery, nanoscale technology, and biotechnology. In this thesis, the synthesis, characterization and physical properties of a new type of Gemini surfactant derived from dinuclear Cu(II) metal complexes is presented. We call these molecules Gemini Metal‐Organic Surfactants (GMOs).

Three newly developed new GMOs (compounds 1‐3) are composed of Cu(II) ions ligated to a lipid‐functionalized triamine group and the metals are …

X-Ray Diffraction Studies Of Room And Intermediate Tempertaure Phases Of Phosphate Based Solid Acids, Kiran Vajrapu

Open Access Theses & Dissertations

In this work, the MH2PO4-type solid acids (where M= Cs, K, Rb) structure and properties are studied and their contribution towards fuel cell industry is understood. Some research groups have shown that, CsH2PO4 (CDP) and RbH2PO4 (RDP) shows sudden, several order of magnitude jumps in their proton conductivity at certain high temperatures.(31, 32) This so called superprotonic behavior of these compounds makes them a fuel cell electrolyte at elevated temperatures. (33) Most of the research groups working on two possible causes to get the reliable information for the high proton conductivity: polymorphic phase transition (Botez et al.,) and thermal dehydration …

Comparison Of Two Environmental Health Education Methods To Reduce Exposure To Residential Pesticides In Hispanic, Patricia M. Juarez-Carrillo

Open Access Theses & Dissertations

ABSTRACT

Exposure to pesticides is associated with adverse health outcomes including poisonings, short-term signs and symptoms, and long-term adverse health outcomes including developmental and cognitive impairments, certain types of cancer, and damages to the endocrine, nervous, and reproductive systems. This study tested two educational methods aimed to help Hispanic, Spanish-speaking mothers living in the U.S.-México border make informed decisions about pesticides applied in their homes. 230 women were randomly allocated to a) a small group talk, b) a graphic booklet, or c) a control group. The outcomes were the knowledge level about the risks of pesticides and the pest prevention …

Estimating The Effect Of Dust And Low Wind Events On Hospitalizations For Asthma While Adjusting For Hourly Levels Of Air Pollutants, Priyangi Kanchana Bulathsinhala

Open Access Theses & Dissertations

El Paso, Texas is known as one of the dust hotspots in North America. We explore the effect of dust and low wind events on asthma admissions in El Paso, Texas between 2000 and 2005. Conditional logistic regression with a case-crossover design was used to estimate the probability of hospitalization after dust and low wind events while controlling for pollutants with hourly monitor measurements, and weather. The historical functional linear model is used to incorporate the hourly pollutant measures into the regression model with a continuous lag, as an alternative to a distributed lag model based on daily averages. The …

The East Jhomolari Fault System And The Timing Of East-West Extension In Northwest Bhutan, John Matthew Cannon

Open Access Theses & Dissertations

This investigation documents a little known, regionally significant, high angle, southeast dipping, system of normal faults in northwest Bhutan, the East Jhomolari Fault System (EJFS). The EJFS trends parallel to the Yadong Gulu rift (YG) and can be traced from Mt. Jhomolari to the northern border with Tibet. This fault zone has been demonstrably active since the last glacial maximum and there is geomorphic evidence of Holocene activity on some fault segments. The structurally lowest EJFS fault, the Lingshi fault appears on some published maps, but the full geographic extent, displacement, onset of faulting, and most recent activity have not …

Asphaltene As Light Harvesting Material In Dye Sensitized Solar Cell, Rajab Emhemed Abujnah

Open Access Theses & Dissertations

This Dissertation characterizes the first asphaltene DSSC (dye-sensitized solar cell), in which light to electricity conversion efficiency has improved from 0 % to 1.8 %. Four natural organic asphaltene factions, namely, un-fractionated asphaltene, Fr. 1 Asphaltene, Fr.2 asphaltene, Fr.3 and Fr.4 were extracted and tested for various solar cell parameters of TiO2 based dye-sensitized solar cell DSSC. DSSCs were fabricated using the four individual asphaltene dyes. The photovoltaic performance of the cells was examined by determining the various parameters such as open-circuit voltage, short-circuit current, fill factor, and series resistance. The overall energy conversion efficiency was also measured to correlate …

Quality Of Wastewater In The El Paso, Texas Region--Analysis Of Pharmaceuticals And Personal Care Products Using High Performance Liquid Chromatography Tandem Mass Spectrometry, Rodolfo Guerrero Jr.

Open Access Theses & Dissertations

Pharmaceuticals and Personal Care Products (PPCPs), such as household cleaning materials, prescription medication, and personal hygiene products, are pollutants of emerging concern that are found in 80% of our water system. Because of their applications, PPCPs are subsequently being released into wastewater; however, current wastewater treatment facilities are not regulated or designed to remove PPCPs. Therefore, these compounds are discharged into the environment on a continual basis. The effects of PPCPs on human health are not yet well known; however, recent research has found that exposure to these chemicals has some adverse developmental effects on aquatic species at low concentrations …

Estimating Statistical Characteristics Under Interval Uncertainty And Constraints: Mean, Variance, Covariance, And Correlation, Ali Jalal-Kamali

Open Access Theses & Dissertations

In many practical situations, we have a sample of objects of a given type. When we measure the values of a certain quantity x for these objects, we get a sequence of values x1, . . . , xn. When the sample is large enough, then the arithmetic mean E of the values xi is a good approximation for the average value of this quantity for all the objects from this class. Other expressions provide a good approximation to statistical characteristics such as variance, covariance, and correlation.

The values xi come from measurements, and measurement is never absolutely accurate.

Often, …

Application Of The Water Poverty Index In Border Colonias Of West Texas, Marcelo Korc

Open Access Theses & Dissertations

This study applied the Water Poverty Index (WPI) in border colonias and other rural areas of west Texas. The colonias are mostly unincorporated communities located primarily in New Mexico and Texas along the border with Mexico and are characterized by high poverty rates and substandard living conditions. In Texas, access to drinking water and sanitation services has been identified as one of the most significant determinants of health in over 350 colonias with about 50 thousand residents.

The WPI is a multidimensional measure that links household welfare with water availability. WPI components were identified and prioritized by a wide range …

Dispersion Geochemistry At Different Scales At The Nopal I Deposit, Peña Blanca Uranium District, Chihuahua, Mexico, Katrina Pekar-Carpenter

Open Access Theses & Dissertations

The Nopal I mine in the Peña Blanca Uranium District, Chihuahua, Mexico is a natural analog for the geologic storage of nuclear waste. This dissertation presents data from two sites within Nopal I: 1) the PB-1 core, which was drilled along the extent of uranium mineralization in the Nopal I mine; and 2) a high-grade stockpile boulder from the mineralized Nopal tuff.

The PB-1 core allowed an investigation into the mineralogical and geochemical changes that are important to research on a nuclear waste repository. Five zones were determined to control these changes: 1) Zone 1, the primary uranium mineralization (quartz-uraninite-pyrite-kaolinite-ilmenite); …

Assessing Data Quality In A Sensor Network For Environmental Monitoring, Gesuri Ramirez

Open Access Theses & Dissertations

Assessing the quality of sensor data in environmental monitoring applications is important, as erroneous readings produced by malfunctioning sensors, calibration drift, and problematic climatic conditions, such as icing or dust, are common.Traditional data quality checking and correction is a painstaking manual process, so the development of automatic systems for this task is highly desirable.

This study investigates machine learning methods to identify and clean incorrect data from a real-world environmental sensor network, the Jornada Experimental Range, located in Southern New Mexico. We evaluated several learning algorithms and data replacement schemes, and developed a method to identify the problematic sensor. The …

Digital Image Processing Based On Sparse Representation And Convex Programming, Carlos Andres Ramirez

Open Access Theses & Dissertations

Sparse representation models have been of central interest in recent years due to important achievements in computational harmonic analysis, such as wavelet transformations, and the most recent sampling theory, compressed sensing. Numerous applications based on sparse models have been studied in the last decade leading to promising results. These applications include areas in seismology, image processing, wireless sensor networks, computed tomography and magnetic resonance imaging just to mention a few.

In this work, we propose to extend such applications in the area of image processing, particularly for the image segmentation problem, and examine algorithms involved in sparse modeling from both …

Development Of Load Balancing Algorithm Based On Analysis Of Multi-Core Architecture On Beowulf Cluster, Damian Valles

Open Access Theses & Dissertations

In this work, analysis, and modeling were employed to improve the Linux Scheduler for HPC use. The performance throughput of a single compute-node of the 23 node Beowulf cluster, Virgo 2.0, was analyzed to find bottlenecks and limitations that affected performance in the processing hardware where each compute-node consisted of two quad-core processors with eight gigabytes of memory. The analysis was performed using the High Performance Linpack (HPL) benchmark.

In addition, the processing hardware of the compute-node was modeled using an Instruction per Cycle (IPC) metric that was estimated using linear regression. Modeling data was obtained by using the Tuning …

A Sparse Representation Technique For Classification Problems, Reinaldo Sanchez Arias

Open Access Theses & Dissertations

In pattern recognition and machine learning, a classification problem refers to finding an algorithm for assigning a given input data into one of several categories. Many natural signals are sparse or compressible in the sense that they have short representations when expressed in a suitable basis. Motivated by the recent successful development of algorithms for sparse signal recovery, we apply the selective nature of sparse representation to perform classification. In order to find such sparse linear representation, we implement an l₁-minimization algorithm. This methodology overcomes the lack of robustness with respect to outliers. In contrast to other classification …

Assessing Measurement Invariance In The Presence Of Testlets, Luis Andres Alvarado

Open Access Theses & Dissertations

Dealing with measurement invariance has been an issue of concern in confirmatory factor analysis for many years. It is important to establish measurement invariance across groups so that instruments may be validly used in multiple groups for comparison of the mean or summative scores. Throughout the years, many studies have considered testing for measurement invariance in factor models. However, there have been no studies that assess measurement invariance when so-called testlets should be modeled in the factor analytic model. Testlets add nuisance covariation to the model which can interfere when trying to detect measurement invariance. In the past, models have …

A Bland–Altman Comparison Of The Lead Care® System And Inductively Coupled Plasma Mass Spectrometry For Detecting Low-Level Lead In Child Whole Blood Samples, Christina Sobin, Tanner Schaub, Natali Parisi, Eva De La Riva

Christina Sobin, Ph.D.

Chronic childhood lead exposure, yielding blood lead levels consistently below 10 μg/dL, remains a major public health concern. Low neurotoxic effect thresholds have not yet been established. Progress requires accurate, efficient, and cost-effective methods for testing large numbers of children. The LeadCare® System (LCS) may provide one ready option. The comparability of this system to the “gold standard” method of inductively coupled plasma mass spectrometry (ICP-MS) for the purpose of detecting blood lead levels below 10 μg/dL has not yet been examined. Paired blood samples from 177 children ages 5.2–12.8 years were tested with LCS and ICP-MS. Triplicate repeat tests …

Rare's Implementation Strategies Of Environmental Conservation In Indonesia, Alvaro Arvizo

Open Access Theses & Dissertations

Like most developing nations, Indonesia is at a crucial stage in its modern political and economic history. Opposing forces are constantly at work, a government struggling to make Indonesia a modern nation and the economic demands of a growing population. This presents the country with a multitude of problems. One of several is that nature's resources are exploited for personal economic gain with no regard for the long-term effects. This is a major concern for environmental conservation and non-profit government organizations (NGOs) worldwide. The American NGO Rare is at the forefront of this issue. Its aim is to meet community …

Pwisegen: A Genetic Algorithms-Based Framework For Pairwise Test Set Generation, Pedro Flores

Open Access Theses & Dissertations

Pairwise testing is a combinatorial testing approach that can be used to reduce the number of test cases dramatically for a software system. It specializes in the type of testing where the outcome of a system depends on the combination of several input parameters. This technique is widely used when there is not enough time to try out all possible combinations of the input parameters involved, because that would be very time consuming. The purpose of pairwise testing technique is to avoid testing all possible value combinations that a system can receive, and to preferably take a representative sample of …

Synthesis And Conjugation Of Terminal Α-Galactose Containing, Roger Allan Ashmus

Open Access Theses & Dissertations

Over 16 million people in Latin America are infected with the protozoan parasite Trypanosoma cruzi (T. cruzi), the causative agent of Chagas disease, and up to 50,000 infected people die annually due to complications during the chronic stage of the disease. To date, there are no vaccines or effective drugs to treat chronic Chagas disease. It is known that T. cruzi contains cell surface mucin-like glycoproteins with terminal α-galactosyl residues, and it is well established that they are highly immunogenic. The exact structure of the immunogenic carbohydrate epitopes, however, remains unknown. To determine which epitopes have the ability to interact …

Results Of New Petrologic And Remote Sensing Studies In The Big Bend Region, Stevan Christian Benker

Open Access Theses & Dissertations

The initial section of this manuscript involves the South Rim Formation, a series of 32.2-32 Ma comenditic quartz trachytic-rhyolitic volcanics and associated intrusives, erupted and was emplaced in Big Bend National Park, Texas. Magmatic parameters have only been interpreted for one of the two diverse petrogenetic suites comprising this formation. Here, new mineralogic data for the South Rim Formation rocks are presented. Magmatic parameters interpreted from these data assist in deciphering lithospheric characteristics during the mid-Tertiary.

Results indicate low temperatures (< 750 °C), reduced conditions (generally below the FMQ buffer), and low pressures (≤ 100 MPa) associated with South Rim Formation magmatism with slight conditional differences between the two suites. Newly discovered fayalite microphenocrysts allowed determination of oxygen fugacity values (between -0.14 and -0.25 ΔFMQ over temperature ranges of 680-700 °C), via mineral equilibria based QUILF95 calculations, for Emory Peak Suite.

Petrologic information is correlated with structural evidence from Trans-Pecos Texas and adjacent regions to evaluate debated timing of tectonic …