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 Decade: 2010-2019
 Collection: UNT Theses and Dissertations
Biomass-Derived Activated Carbon through Self-Activation Process

Biomass-Derived Activated Carbon through Self-Activation Process

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Date: May 2016
Creator: Xia, Changlei
Description: Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up process will cause environmental concerns. In comparison with these conventional activation processes, the self-activation process could avoid the cost of activating agents and is more environmentally friendly, since the exhaust gases (CO and H2) can be used as fuel or feedstock for the further synthesis in methanol production. In this research, many types of biomass were successfully converted into activated carbon through the self-activation process. An activation model was developed to describe the changes of specific surface area and pore volume during the activation. The relationships between the activating temperature, dwelling time, yield, specific surface area, and specific pore volume were detailed investigated. The highest specific surface area and pore volume of the biomass-derived activated carbon through the self-activation process ...
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Hungering for Independence: The Relationship between Food and Morale in the Continental Army, 1775-1783

Hungering for Independence: The Relationship between Food and Morale in the Continental Army, 1775-1783

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Date: May 2016
Creator: Maxwell, Nancy
Description: An adequate supply of the right kinds of foods is critical to an army's success on the march and on the battlefield. Good food supplies and a dire lack of provisions have profound effects on the regulation, confidence, esprit de corps, and physical state of an army. The American War of Independence (1775-1783) provides a challenging case study of this principle. The relationship between food and troop morale has been previously discussed as just one of many factors that contributed to the success of the Continental Army, but has not been fully explored as a single issue in its own right. I argue that despite the failures of three provisioning system adopted by the Continental Congress - the Commissariat, the state system of specific supplies, and the contract system - the army did keep up its morale and achieve the victory that resulted in independence from Great Britain. The evidence reveals that despite the poor provisioning, the American army was fed in the field for eight years thanks largely to its ability to forage for its food. This foraging system, if it can be called a system, was adequate to sustain morale and perseverance.
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Design of New Monodentate Ligands for Regioselectivity and Enantioselectivity Tuning in Late Transition Metal Catalysis

Design of New Monodentate Ligands for Regioselectivity and Enantioselectivity Tuning in Late Transition Metal Catalysis

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Date: May 2016
Creator: Ruch, Aaron Anthony
Description: The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of new acyclic diaminocarbenes was developed and a study of the ligand effects on the regioselectivity of a gold-catalyzed domino enyne cyclization hydroarylation reaction and a Nazarov cyclization was undertaken. New chiral acyclic diaminocarbenes were also developed and tested along side new C3-symmetric phosphite ligands in an asymmetric intramolecular hydroamination of allenes. Structure activity correlations were developed for the potential use in further rational ligand design. The synthesis of 6a,7-dihydro-5-amino-dibenzo[c,g]chromene derivatives via a gold-catalyzed domino reaction of alkynylbenzaldehydes in the presence of secondary amines was developed. These were sent to be screened for biological activity.
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Electrodeposited Metal Matrix Composites for Enhanced Corrosion Protection and Mechanical Properties

Electrodeposited Metal Matrix Composites for Enhanced Corrosion Protection and Mechanical Properties

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Date: May 2016
Creator: Thurber, Casey Ray
Description: In the oil and gas industry, high corrosion resistance and hardness are needed to extend the lifetime of the coatings due to exposure to high stress and salt environments. Electrodeposition has become a favorable technique in synthesizing coatings because of low cost, convenience, and the ability to work at low temperatures. Electrodeposition of metal matrix composites has become popular for enhanced corrosion resistance and hardness in the oil and gas industry because of the major problems that persist with corrosion. Two major alloys of copper-nickel, 90-10 and 70-30, were evaluated for microbial corrosion protection in marine environments on a stainless steel substrate. Copper and copper alloys are commonly used in marine environments to resist biofouling of materials by inhibiting microbial growth. Literature surveying the electrodeposition of Cu-Ni incorporated with nano- to micro- particles to produce metal matrix composites has been reviewed. Also, a novel flow cell design for the enhanced deposition of metal matrix composites was examined to obtain the optimal oriented structure of the layered silicates in the metal matrix. With the addition of montmorillonite into the Ni and Cu-Ni matrix, an increase in strength, adhesion, wear and fracture toughness of the coating occurs, which leads to an increase ...
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Fatigue Behavior of A356 Aluminum Alloy

Fatigue Behavior of A356 Aluminum Alloy

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Date: May 2016
Creator: Nelaturu, Phalgun
Description: Metal fatigue is a recurring problem for metallurgists and materials engineers, especially in structural applications. It has been responsible for many disastrous accidents and tragedies in history. Understanding the micro-mechanisms during cyclic deformation and combating fatigue failure has remained a grand challenge. Environmental effects, like temperature or a corrosive medium, further worsen and complicate the problem. Ultimate design against fatigue must come from a materials perspective with a fundamental understanding of the interaction of microstructural features with dislocations, under the influence of stress, temperature, and other factors. This research endeavors to contribute to the current understanding of the fatigue failure mechanisms. Cast aluminum alloys are susceptible to fatigue failure due to the presence of defects in the microstructure like casting porosities, non-metallic inclusions, non-uniform distribution of secondary phases, etc. Friction stir processing (FSP), an emerging solid state processing technique, is an effective tool to refine and homogenize the cast microstructure of an alloy. In this work, the effect of FSP on the microstructure of an A356 cast aluminum alloy, and the resulting effect on its tensile and fatigue behavior have been studied. The main focus is on crack initiation and propagation mechanisms, and how stage I and stage II cracks ...
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Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement

Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement

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Date: May 2016
Creator: Yao, Shulong
Description: This thesis aims to develop a new type of highly stretchable strain sensor to measure large deformation of a specimen subjected to dynamic loading. The sensor was based on the piezo-resistive response of carbon nanotube(CNT)/polydimethysiloxane (PDMS) composites thin films, some nickel particles were added into the sensor composite to improve the sensor performance. The piezo-resistive response of CNT composite gives high frequency response in strain measurement, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measuring large strain (up to 26%) with an excellent linearity and a fast frequency response under quasi-static test, the delay time for high strain rate test is just 30 μs. This stretchable strain sensor is also able to exhibit much higher sensitivities, with a gauge factor of as high as 80, than conventional foil strain gauges.
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Decision Makers’ Cognitive Biases in Operations Management: An Experimental Study

Decision Makers’ Cognitive Biases in Operations Management: An Experimental Study

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Date: May 2016
Creator: Alkhars, Mohammed
Description: Behavioral operations management (BOM) has gained popularity in the last two decades. The main theme in this new stream of research is to include the human behavior in Operations Management (OM) models to increase the effectiveness of such models. BOM is classified into 4 areas: cognitive psychology, social psychology, group dynamics and system dynamics (Bendoly et al. 2010). This dissertation will focus on the first class, namely cognitive psychology. Cognitive psychology is further classified into heuristics and biases. Tversky and Kahneman (1974) discussed 3 heuristics and 13 cognitive biases that usually face decision makers. This dissertation is going to study 6 cognitive biases under the representativeness heuristic. The model in this dissertation states that cognitive reflection of the individual (Frederick 2005) and training about cognitive biases in the form of warning (Kaufmann and Michel 2009) will help decisions’ makers make less biased decisions. The 6 cognitive biases investigated in this dissertation are insensitivity to prior probability, insensitivity to sample size, misconception of chance, insensitivity to predictability, the illusion of validity and misconception of regression. 6 scenarios in OM contexts have been used in this study. Each scenario corresponds to one cognitive bias. Experimental design has been used as the research ...
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Community-based Logistics and Supply Chain Management: Developing, Testing and Validating Conceptual Models

Community-based Logistics and Supply Chain Management: Developing, Testing and Validating Conceptual Models

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Date: May 2016
Creator: Obaze, Yolanda
Description: The field of Logistics and Supply Chain Management (LSCM) suggests that transactions, collaboration, and value are important in the supply and delivery of products and services to meet the need of impoverished end-consumers. In many cases, the application of LSCM is paramount in most strategic decision-making efforts. Therefore, this research explores the applications of LSCM processes and activities within the community-based context. The methodology used to address the research questions consisted of a hybrid of mixed methods. This mixed methodology provides three essays that investigate the application and development of LSCM in the community-based context. The essays address the flow of charitable products and services through supply chains. The dissertation does not pay close attention to the first-tier suppliers’ suppliers, which is looking at the originating flow of goods and services (raw materials, manufacturing, etc.). However, the dissertation puts a focus on products and services supplied to focal organizations and how these products are then passed on to end-consumers. Essay I looks at the transaction (costs) that ensue from the supply of charitable products. Essay II analyzes a social service ecosystem and investigates how the network of organizations enable the distribution of charitable products and services. Lastly, Essay III examines ...
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'My Tattooed Mind'

'My Tattooed Mind'

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Date: May 2016
Creator: Mayo, Kaleb R
Description: This thesis features a collection of nonfiction essays.
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Stable Nanocrystalline Au Film Structures for Sliding Electrical Contacts

Stable Nanocrystalline Au Film Structures for Sliding Electrical Contacts

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Date: May 2016
Creator: Mogonye, Jon-Erik
Description: Hard gold thin films and coatings are widely used in electronics as an effective material to reduce the friction and wear of relatively less expensive electrically conductive materials while simultaneously seeking to provide oxidation resistance and stable sliding electrical contact resistance (ECR). The main focus of this dissertation was to synthesize nanocrystalline Au films with grain structures capable of remaining stable during thermal exposure and under sliding electrical contact stress and the passing of electrical current. Here we have utilized a physical vapor deposition (PVD) technique, electron beam evaporation, to synthesize Au films modified by ion implantation and codeposited ZnO hardened Au nanocomposites. Simultaneous friction and ECR experiments of low fluence (< 1x10^17 cm^-2) He and Ar ion implanted Au films showed reduction in friction coefficients from ~1.5 to ~0.5 and specific wear rates from ~4x10^-3 to ~6x10^-5 mm^3/N·m versus as-deposited Au films without significant change in sliding ECR (~16 mΩ). Subsurface microstructural changes of He implanted films due to tribological stress were analyzed via site-specific cross-sectional transmission electron microscopy (TEM) and revealed the formation of nanocrystalline grains for low energy (22.5 keV) implantation conditions as well as the growth and redistribution of cavities. Nanoindentation hardness results revealed an increase ...
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Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium-Chromium Alloys

Microstructural Phase Evolution In Laser Deposited Compositionally Graded Titanium-Chromium Alloys

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Date: May 2016
Creator: Thomas, Jonova
Description: A compositionally graded Ti-xCr (10≤x≤30 wt%) alloy has been fabricated using Laser Engineered Net Shaping (LENSTM) to study the microstructural phase evolution along a compositional gradient in both as-deposited and heat treated conditions (1000°C followed by furnace cooling or air cooling). The alloys were characterized by SEM BSE imaging, XRD, EBSD, TEM and micro-hardness measurements to determine processing-structure-property relations. For the as-deposited alloy, α-Ti, β-Ti, and TiCr2 (C15 Laves) phases exist in varying phase fractions, which were influential in determining hardness values. With the furnace cooled alloy, there was more homogeneous nucleation of α phase throughout the sample with a larger phase fraction of TiCr2 resulting in increased hardness values. When compared to the air cooled alloy, there was absence of wide scale nucleation of α phase and formation of ω phase within the β phase due to the quicker cooling from elevated temperature. At lower concentrations of Cr, the kinetics resulted in a diffusionless phase transformation of ω phase with increased hardness and a lower phase fraction of TiCr2. In contrast at higher Cr concentrations, α phase separation reaction occurs where the β phase is spinodally decomposed to Cr solute-lean β1 and solute-rich β2 resulting in reduced hardness.
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Medical comorbidity in the course of bipolar disorder.

Medical comorbidity in the course of bipolar disorder.

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Date: May 2016
Creator: Smith, Patrick M
Description: Bipolar disorder is a serious illness affecting approximately 2-4% of the population and is one of the world’s leading causes of disability. In individuals with bipolar disorder, medical comorbidity associated with cardiovascular, respiratory and endocrine disorders is related to increased rates of mortality. Recent updates to multi-system inflammatory related conceptualizations of bipolar disorder focus on the unique power that medical illness and biological processes may play as factors associated with course and outcome in bipolar disorder. The current study examined medical comorbidity and its associations with various demographic and psychological variables in individuals with bipolar disorder, schizophrenia, and major depressive disorder with psychotic features followed for 10 years from their first hospital admission. When compared to an age, gender and race-matched control sample from the population, those with bipolar disorder had significantly higher medical comorbidity across a range of medical diagnoses both at 6 months and 10 years after first hospital admission. Ten years following initial hospitalization, individuals in all three diagnostic groups reported increased rates of diabetes (OR: 2.0 – 3.7), stroke (OR: 4.6 – 7.0) and asthma (OR: 1.9 - 3.1), and individuals with bipolar disorder reported increased rates of cancer (OR = 2.1). A number of psychological ...
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Interfacial Electrochemistry of Cu/Al Alloys for IC Packaging and Chemical Bonding Characterization of Boron Doped Hydrogenated Amorphous Silicon Films for Infrared Cameras

Interfacial Electrochemistry of Cu/Al Alloys for IC Packaging and Chemical Bonding Characterization of Boron Doped Hydrogenated Amorphous Silicon Films for Infrared Cameras

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Date: May 2016
Creator: Ross, Nick Mark
Description: We focused on a non-cooling room temperature microbolometer infrared imaging array device which includes a sensing layer of p-type a-Si:H component layers doped with boron. Boron incorporation and bonding configuration were investigated for a-Si:H films grown by plasma enhanced chemical deposition (PECVD) at varying substrate temperatures, hydrogen dilution of the silane precursor, and dopant to silane ratio using multiple internal reflection infrared spectroscopy (MIR-IR). This study was then confirmed from collaborators via Raman spectroscopy. MIR-IR analyses reveal an interesting counter-balance relationship between boron-doping and hydrogen-dilution growth parameters in PECVD-grown a-Si:H. Specifically, an increase in the hydrogen dilution ratio (H2/SiH4) or substrate temperature was found to increase organization of the silicon lattice in the amorphous films. It resulted in the decrease of the most stable SiH bonding configuration and thus decrease the organization of the film. The new chemical bonding information of a-Si:H thin film was correlated with the various boron doping mechanisms proposed by theoretical calculations. The study revealed the corrosion morphology progression on aluminum alloy (Al, 0.5% Cu) under acidic chloride solution. This is due to defects and a higher copper content at the grain boundary. Direct galvanic current measurement, linear sweep voltammetry (LSV), and Tafel plots are used ...
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Unpacking Self in Clutter and Cloth: Curator as Artist/Researcher/Teacher

Unpacking Self in Clutter and Cloth: Curator as Artist/Researcher/Teacher

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Date: May 2016
Creator: McCartney, Laura Lee
Description: This a/r/tographic dissertation offers opportunities to interrogate curator identity and curator ways of being in both public and private spaces. Instead of an authoritative or prescriptive look at the curatorial, this dissertation as catalogue allows for uncertainty, for messiness, for vulnerable spaces where readers are invited into an exhibition of disorderly living. Stitched throughout the study are stories of mothering and the difficulties that accompanied the extremely early birth of my daughter. Becoming a mother provoked my curating in unexpected ways and allowed me to reconsider the reasons I collect, display, and perform as a curator. It was through the actual curating of familial material artifacts in the exhibition Dress Stories, I was able to map the journey of my curatorial turns. My engagement with clothing in the inquiry was informed by the work of Sandra Weber and Claudia Mitchell, where dress as a methodology allows for spaces to consider autobiography, identity, and practice. It was not until the exhibition was over, I was able to discover new ways to thread caring, collecting, and cataloging ourselves as curators, artists, researchers, teachers, and mothers. It prompts curators and teachers to consider possibilities for failure, releasing excess, and uncaring as a way ...
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Virtual Entrepreneurship: Explicating the Antecedents of Firm Performance

Virtual Entrepreneurship: Explicating the Antecedents of Firm Performance

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Date: May 2016
Creator: Chandna, Vallari
Description: Prior research has examined entrepreneurial businesses spatially located in the physical or offline context; however, recent radical information and technological breakthroughs allow entrepreneurs to launch their businesses completely online. The growth of the online business industry has been phenomenal. Predictions for worldwide online sales estimate it to reach $2 trillion in 2016. Virtual entrepreneurship refers to the pursuit and exploitation of opportunities via virtual platforms. Web 2.0 cybermediaries offer web-based platforms that function similarly to traditional intermediaries in a virtual setting and minimize barriers to entry for virtual entrepreneurial firms. The use of such cybermediaries with increasing success suggests an implicit shift in the dominant logic that typically underpins the functioning of entrepreneurial firms operating in the physical world. In this relatively uncharted territory, marked by a focus on profit, cooperation, collaboration and community, three ideal-type institutional logics i.e. Market, Corporation and Community, blend together. It is posited that a Virtual Entrepreneurial Logic guides the norms, behaviors, and practices of entrepreneurial firms operating via these virtual platforms. This raises the question whether the blending of three ideal-type logics leads to the existence of different antecedents of performance. A business model antecedent addressing the economic dimension, a community antecedent addressing the ...
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Social Anxiety and Non-Medical Prescription Stimulant Use among College Students

Social Anxiety and Non-Medical Prescription Stimulant Use among College Students

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Date: May 2016
Creator: Cloutier, Renee
Description: Current evidence suggests that non-medical prescription stimulant (NMPS) use is on the rise, particularly among college students. Identifying individuals at risk for regular and problematic use is a critical step towards the development of effective intervention efforts. A growing body of work has noted that individuals with elevated levels of social anxiety (SA) or social anxiety disorder are at an enhanced risk for developing substance use problems, including NMPS use disorder. Despite the relevance of SA and NMPS use among college students, no studies have attempted to examine subclinical SA or the relation between SA and NMPS use among college students specifically. Thus, the present study sought to extend this area by testing the relation of SA symptoms and NMPS use frequency among college students. A large online study of college students was conducted (N=1604) to identify 252 NMPS users (18-25 years; 68.3% female). A hierarchical linear regression was used to test the moderation of positive prescription stimulant expectancies on SA symptoms in predicting past year NMPS use frequency. A subsample of 15 participants was also brought into the lab to assess subjective (State Anxiety) and physiological (salivary cortisol) responding to a social stressor task. Overall, the current study did ...
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Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

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Date: May 2016
Creator: Wu, Min
Description: Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer MoS2 on the SiO2/Si substrate is 7.78 J/m2. The practical adhesion energy was found to be an increasing function of the MoS2 thickness. Unlike SiO2/Si substrates, MoS2 films grown on the sapphire possess higher bonding energy, which is attributed to the defect-free growth and less number of grain boundaries, as well as less stress and strain stored at the interface owing to the similarity of Thermal Expansion Coefficient (TEC) between MoS2 films and sapphire substrate. Furthermore, we calculated the surface free energy of 2D MoS2 by the facile contact angle measurements and Neumann model fitting. A surface free energy ~85.3 mJ/m2 in few layers thick MoS2 manifests the hydrophilic nature of 2D MoS2. The high surface energy of MoS2 helps explain the good bonding strength at MoS2/substrate interface. This simple adhesion ...
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Development of an Instrument to Measure the Level of Acceptability and Tolerability of  Cyber Aggression: Mixed-Methods Research on Saudi Arabian Social Media Users

Development of an Instrument to Measure the Level of Acceptability and Tolerability of Cyber Aggression: Mixed-Methods Research on Saudi Arabian Social Media Users

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Date: May 2016
Creator: Albar, Ali A
Description: Cyber aggression came about as a result of advances in information communication technology and the aggressive usage of the technology in real life. Cyber aggression can take on many forms and facets. However, the main focus of this study is cyberbullying and cyberstalking through information sharing practices that might constitute digital aggressive acts. Human aggression has been extensively investigated. Studies focusing on understanding the causes and effects that can lead to physical and digital aggression have shown the prevalence of cyber aggression in different settings. Moreover, these studies have shown strong relationship between cyber aggression and the physiological and physical trauma on both perpetrators and their victims. Nevertheless, the literature shows a lack of studies that could measure the level of acceptance and tolerance of these dangerous digital acts. This study is divided into two main stages; Stage one is a qualitative pilot study carried out to explore the concept of cyber aggression and its existence in Saudi Arabia. In-depth interviews were conducted with 14 Saudi social media users to collect understanding and meanings of cyber aggression. The researcher followed the Colaizzi’s methods to analyze the descriptive data. A proposed model was generated to describe cyber aggression in social media ...
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With the Earth in Mind: Ecological Grief in the Contemporary American Novel

With the Earth in Mind: Ecological Grief in the Contemporary American Novel

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Date: May 2016
Creator: Reis, Ashley Elaine
Description: "With the Earth in Mind" responds to some of the most cutting-edge research in the field of ecocriticism, which centers on ecological loss and the grief that ensues. Ecocritics argue that ecological objects of loss abound--for instance, species are disappearing and landscapes are becoming increasingly compromised--and yet, such loss is often deemed "ungrievable." While humans regularly grieve human losses, we understand very little about how to genuinely grieve the loss of nonhuman being, natural environments, and ecological processes. My dissertation calls attention to our society's tendency to participate in superficial nature-nostalgia, rather than active and engaged environmental mourning, and ultimately activism. Herein, I investigate how an array of postwar and contemporary American novels represent a complex relationship between environmental degradation and mental illness. Literature, I suggest, is crucial to investigations of this problem because it can reveal the human consequences of ecological loss in a way that is unavailable to political, philosophical, scientific, and even psychological discourse.
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A Phenomenology of Fostering Learning: Alternate Reality Games and Transmedia Storytelling

A Phenomenology of Fostering Learning: Alternate Reality Games and Transmedia Storytelling

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Date: May 2016
Creator: Wakefield, Jenny S
Description: This dissertation presents the essence of the experience of instructional designers and instructors who have used alternate reality games (ARGs) and transmedia storytelling (TS) for teaching and learning. The use of game-like narratives, such as ARGs and TS, is slowly increasing. However, we know little about the lived experiences of those who have implemented such transmedia experiences in formal or informal learning. The data consists of written transcripts from interviews with 11 co-researchers in the United States and Europe. Phenomenology was the guiding methodology. The study begins by reviewing storytelling and the use of games in learning, leading up to exploring the tradition of using ARGs and TS in learning contexts. The analysis was one of reduction leading to codes, summary stories, themes, and the essence of the experience. Co-researchers used many techniques to enlighten their learners including problem-solving, critical thinking, collaboration, encouragement, disruption, and connection-making. When successful, connection-making facilitates learner agency development by providing learners with the power to act by their own initiative. Action came through the communicated narratives and games that closely tied to real-world problems. In the context of these efforts, this study's co-researchers emerged as educational life-world learning-coaches, "sensei", who were each using strategies and ...
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Predicting Posttraumatic Stress Disorder Symptoms During Adolescence: A Longitudinal Study of The Role of Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysfunction

Predicting Posttraumatic Stress Disorder Symptoms During Adolescence: A Longitudinal Study of The Role of Hypothalamic-Pituitary-Adrenal (HPA) Axis Dysfunction

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Date: May 2016
Creator: Liu, Keke
Description: Posttraumatic stress disorder (PTSD) is a trauma-related disorder that may develop in response to traumatic or stressful events. Dysfunction of the Hypothalamic-Pituitary-Adrenal (HPA) axis has been implicated in the disorder. Studies support such dysfunction as being a consequence of PTSD, rather than a precursor. However, most studies of the HPA are either cross-sectional or have been carried out in adults. The aim of the present study was to identify whether HPA dysregulation interacts with stressful experiences to increase the likelihood of developing PTSD symptoms in a community-recruited sample of healthy adolescent girls. Adolescent girls (N = 550) and one of their parents participated. Adolescents’ clinical symptoms were assessed at baseline and at a nine month follow-up. Saliva samples were collected from all adolescent participants at waking, 30 minutes after waking, and 8 pm on 3 consecutive days. Flattened diurnal slope of cortisol at baseline was associated with increased PTSD symptoms nine months later. Baseline cortisol awakening response (CAR) per se was not prospectively related to developing PTSD symptoms, but its interactions with stressful experience was associated with elevated PTSD symptoms at follow-up. Effects were small and need to be replicated in samples with more severe stressors, as well as more ...
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Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers

Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers

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Date: May 2016
Creator: Vaughan, Haydn
Description: The HVAC&R industry is looking to transition from copper-aluminum heat exchangers to all-aluminum microchannel technology. The want for the transition stemmed from seeing the performance improvement of all-aluminum microchannel radiators in the automotive industry. Applications differ between the two industries; therefore, applying this technology for HVAC&R use must be validated. Research towards operating modes of an all-aluminum heat exchanger in a defined corrosive environment will provide the industry with a better understanding of heat exchanger design and heat exchanger material selection. The worth in this is preventing overdesign and producing more efficient heat exchangers. Furthermore, ASHRAE members and the corrosion community will find value in a defined corrosion system and corrosion test procedure. The information gained through past research has progressed assessment of material performance; however, the methods improperly simulate and expedite natural weathering. The most common method being used is the ASTM (American Society of Testing Materials) Sea Water Acetic Acid Test. The research discussed in this paper was focused on improving a standard corrosion system by implementing system modifications to simulate heat exchanger operation while performing a modified wet-dry cyclic test (e.g. ASTM G85 Annex 5). The goal is to produce results that are more representative of natural ...
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Quantum Coherent Control and Propagation in Lambda System

Quantum Coherent Control and Propagation in Lambda System

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Date: May 2016
Creator: Singh, Pooja
Description: Strong coherence in quasi-resonant laser driven system interferes with effective relaxations, resulting in behaviors like, coherent population trapping and Electromagnetically induced transparency. The Raman system can optimize this utilizing excited coherence in the lambda system when exposed to counter- intuitive pump-stokes pulses. The phenomenon can result in complete population transfer between vibrational levels called Stimulated Raman adiabatic passage(STIRAP). STIRAP and CHIRAP have been studied with Gaussian and chirped pulses. The optical propagation effects in dense medium for these phenomenon is studied to calculate the limitations and induced coherences. Further, the effect of rotational levels has been investigated. The molecular vibrational coherence strongly depends on the effect of rotational levels. The change in coherence interaction for ro-vibrational levels are reported and explained. We have considered the effects on the phase of radiation related to rotational mechanical motion of quantum system by taking advantages in ultra strong dispersion medium provided by quantum coherence in lambda system. The enhanced Fizeau effect on a single atom is observed.
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Eaten: A Novel

Eaten: A Novel

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Date: May 2016
Creator: Foster, Natalie
Description: This novel operates on two levels. First, it is a story concerning the fate of a young woman named Raven Adams, who is prompted into journeying westward after witnessing what she believes to be an omen. On another level, however, the novel is intended to be a philosophical questioning of western modes of “science-based” singular conceptualizations of reality, which argue that there is only one “real world” and anyone who deviates from this is “crazy,” “stupid,” or “wrong.” Raven as a character sees the world in terms of what might be called “magical thinking” in modern psychology; her closest relationship is with a living embodiment of a story, the ancient philosopher Diogenes, which she believes is capable of possessing others and directing her journey. As the story continues the reader comes to understand Raven’s perceptions of her reality, leading to a conceptualization of reality as being “multi-layered.” Eventually these layers are collapsed and unified in the final chapters. The novel makes use of many reference points including philosophy, classical mythology, folklore, religion, and internet social media in order to guide the reader along Raven’s story.
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