Doctor of Philosophy (Ph.D.), University of Dayton, 2014, Electro-Optics

The objective of this dissertation is to evaluate and develop novel sources for tunable narrowband IR generation, tunable narrowband THz generation, and ultra-wideband RF generation to be used in possible non-destructive evaluation systems. Initially a periodically poled Lithium Niobate (PPLN) based optical parametric amplifier (OPA) is designed using a double-pass configuration where a small part of the pump is used on the first pass to generate a signal, which is reflected and filtered by an off-axis etalon. The portion of the pump that is not phase matched on the first pass is retro-reflected back into the PPLN crystal and is co-aligned with the narrow bandwidth filtered signal and amplified. We demonstrate that the system is tunable in the 1.4 µm -1.6 µm signal range with a linewidth of 5.4 GHz. Next the outputs of seeded, dual periodically poled lithium niobate (PPLN) optical parametric amplifiers (OPA) are combined in the nonlinear crystal 4-dimthylamino-N-methyl-4-stilbazolium-tosylate (DAST) to produce a widely tunable narrowband THz source via difference frequency generation (DFG). We have demonstrated that this novel configuration enables the system to be seamlessly tuned, without mode-hops, from 1.2 THz to 26.3 THz with a minimum bandwidth of 3.1 GHz. The bandwidth of the source was measured by using the THz transmission spectrum of water vapor lines over a 3-meter path length. By selecting of the DFG pump wavelength to be at 1380 nm and the signal wavelength to tune over a range from 1380 nm to 1570 nm, we produced several maxima in the output THz spectrum that was dependent on the phase matching ability of the DAST crystal and the efficiency of our pyro-electric detector. Due to the effects of dispersive phase matching, filter absorption of the THz waves, and two-photon absorption multiple band gaps in the overall spectrum occur and are discussed. Employing the dual generator scheme, we have obtained THz images at several locations in the spect (open full item for complete abstract)

Committee: Joseph Haus (Committee Chair) Subjects: Optics

Master of Science (MS), Wright State University, 2013, Earth and Environmental Sciences

Nanoscale particles of zero valent iron stabilized with carboxymethylcellulose (CMC-nZVI) have been shown to degrade chlorinated hydrocarbons efficiently in bench-scale investigations. The remediation of contaminated sites by subsurface injection of stabilized nZVI in a slurry form has been investigated at pilot scale and field scale with conflicting results concerning transport of stabilized nZVI and its long-term stability for in situ degradation of chlorinated hydrocarbons. Changes in the hydraulic conductivity in porous media have also been reported following injection of stabilized nZVI slurry in both large tank experiments and in field studies. This study investigated the leaching behavior of CMC-nZVI post-emplacement at a variety of CMC concentrations (1 g/L, 2 g/L, 4 g/L, and 8 g/L) in a sand-filled flow-through reactor (30 cm long x 5 cm diameter). The goal was to identify changes in total iron mass eluted and changes to the hydraulic properties of the column post-emplacement of CMC-nZVI for different CMC concentrations. Experiments were also conducted to determine the amount of unreacted CMC-nZVI that would elute the column post-emplacement. Prior to injection of the CMC-nZVI, tracer breakthough studies were analyzed using the Method of Moments to determine velocity, resulting in calculation based estimations for pore volume (PV) and porosity. CXTFIT, a parameter estimation based on the physical non-equilibrium convection-dispersion equation, was used to demine initial conditions within the column for longitudinal dispersivity, mobile porosity, and the rate of mass transfer from mobile to immobile zones. The CMC-nZVI slurry was emplaced by rapid injection into the sand column through the base at a rate of ~120 mL/min and then flushed with a 10 mM NaCl solution at a velocity of 1 m/d (0.5 mL/min). After CMC-nZVI emplacement, the effluent samples exiting the flow-through reactor were collected with fraction collector for 15 min sampling (open full item for complete abstract)

Committee: Abinash Agrawal Ph.D. (Advisor); Mark Goltz Ph.D. (Advisor); Robert Ritzi Ph.D. (Committee Member) Subjects: Environmental Geology; Environmental Science; Geochemistry; Hydrologic Sciences; Hydrology; Nanoscience; Nanotechnology

Master of Science in Engineering, University of Akron, 2023, Engineering

Ceramic matrix composites and environmental barrier coatings require high temperature and high velocity tests to approach jet engine and hypersonic conditions for hot section parts. Previous testing at the University of Akron used a high velocity oxygen fuel (HVOF) burner rig system that manually controlled the position of the torch using an unstable extruded aluminum frame. This caused issues with repeatability, accuracy, and consistency of the experiment, and limited the opportunity for thermo-mechanical fatigue conditions. In pursuit of expanding testing capabilities, the burner rig has been automated with respect to a fixed sample in a horizontally mounted MTS 810 system. The two-axis positioner was created using ball screws rotated with 2.0 Nm stepper motors controlled via a .NET based Graphic User Interface (GUI) controller. Torch motion is controlled through two-axes, one perpendicular to the sample (z-axis) and the other parallel along the width direction of the sample (y-axis). Through this system, the torch is moved perpendicular from the specimen, changing the distance to the sample and the resulting surface temperature. Sample temperature can be changed through two main methods: moving the torch, or by changing the flow rates and pressures of the combustion gases. At constant flow rates and pressures, the closer the torch, the higher the surface temperature as measured by a FLIR IR camera and a two-color pyrometer. This new testing system allows for thermo-mechanical fatigue experiments by changing the position of the torch in a set pattern to create various test conditions not possible with the previous setup, e.g., to mimic an aircraft's takeoff, cruise, and landing cycle. Sample temperature is a vital parameter as the temperature increases, the more damage accumulates from the harsh condition. The torch positioner, in temperature mode, can maintain a set temperature based on feedback received from the two-color pyrometer. The development of the (open full item for complete abstract)

Committee: Manigandan Kannan (Committee Member); Gregory Morscher (Advisor) Subjects: Mechanical Engineering

Doctor of Business Administration (D.B.A.), Franklin University, 2022, Business Administration

Higher Education Institutions (HEIs) need to stay abreast of advances in communication technologies to be student centric, but institutional adoption of Short Messaging Service (SMS) text varies widely and research on incorporation for advising is limited (Arnold et al., 2020; IPEDS 2020; Santos et al., 2018). This quantitative study explored advisor use and perceptions on values, motives, and institutional support of SMS texting as a communication channel with students and the possible variables impacting those factors. Theoretical concepts in Customer Relationship Management (CRM) and adaptive leadership guided the study as well as existing survey research on Computer Mediated Communication (CMC) in higher education (Duran et al., 2005). Survey responses from 402 advisors nationwide were analyzed through descriptive and inferential statistics. SMS use was reported among all genders, experience levels, and programmatic formats and advisors overall had a positive view of the communication channel. Motives for use varied between subgroups within the sample and SMS was predominantly used to gain access to richer mediums. A statistically significant association between learning environment and SMS incorporation indicated that online advisors were more likely to use SMS texting for student communication. A statistically significant difference was also identified between median institutional support scores for SMS users and non-users with the directionality indicating users were more likely from SMS supportive institutions. Furthermore, advisors reported using SMS texting for both transactional and relational communication, even when their institution did not support the channel with training, policies, or technology. The study sheds light on the prevalence of SMS use and calls for leadership to gain greater awareness of their local-level policies, industry-wide practices, and system integrated options in managing the university-to-student connection. For HEIs (open full item for complete abstract)

Committee: Brenda Jones (Committee Chair); Yuerong Sweetland (Committee Member); Patrick Bennett (Committee Member) Subjects: Adult Education; Business Administration; Business Education; Communication; Continuing Education; Education Policy; Educational Evaluation; Educational Leadership; Educational Software; Educational Technology; Higher Education; Higher Education Administration; Management; Mass Communications

PHD, Kent State University, 2020, College of Communication and Information / School of Communication Studies

The primary goal of this investigation was to explore how people maintain regular exercise by using interpersonal communication to gain social support in Facebook Groups. Supportive communication is essential to maintain regular exercise (Ntoumanis, Quested, Reeve, & Cheon, 2018). Given obesity's association with the numerous health risks, tackling this problem is imperative. Participants (n=159) were recruited through Amazon's MTurk. Individuals reported their communication activity (i.e., liking, posting, commenting, and scrolling) in Facebook Groups and regular exercise (i.e., frequency, type, and duration) over the previous thirty days. Additionally, participants completed the following measures: Computer Mediated Communication Competence, The Online Social Support Scale, Self-Efficacy for Exercise, Exercise Benefits and Barriers Scale, and The Short Self-Regulation Scale. Multiple Regression analysis was used to determine how Social Cognitive Theory (i.e., self-efficacy, self-regulation, and the environment), communication, and social support contribute to engaging in regular exercise.

Committee: Nichole Egbert PhD (Committee Chair) Subjects: Communication

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2020, Higher Education Administration

The purpose of this study was to provide a phenomenological description of peer interaction and to explore the sense of community experienced by online learners in an accelerated online course delivered asynchronously. Though research indicates the importance of peer interaction and community in online learning, and online learners indicate their desire to feel a sense of community in online courses, there is a gap in literature that qualitatively details the essence of peer interaction and online learners' perception of community. To address this gap, I interviewed six post-traditional online learners regarding their experiences interacting with peers and the way those experiences contributed to their sense of community in an accelerated online course. Five main themes emerged based on participants' experiences and perceptions: (1) Routine, (2) Technology, (3) Course Design, (4) Perceptions of Interaction, (5) Sense of Community. The findings represented throughout this research align with the two research questions that guided this study: (1) How do students describe their experiences interacting with peers in an accelerated online course? (2) How do students describe their experiences of interacting with peers as contributing to their sense of community in an accelerated online course? This research contributes to a deeper understanding of factors that shape peer interaction and the sense of community felt in an accelerated online learning context. The findings evidence implications for online pedagogy, learning management systems, and for the implementation of the Community of Inquiry framework. Future research that focuses on the experiences and perceptions of online learners who share similar or different demographic characteristics through various methods would enhance understanding of peer interaction and community in online learning contexts. The need for such research is evident as diverse student populations' exposure to learning through distance, onl (open full item for complete abstract)

Committee: Kenneth Borland Ph.D (Advisor); Marlise Lonn Ph.D. (Other); Ellen Broido Ph.D. (Committee Member); Jessica Turos Ph.D. (Committee Member) Subjects: Communication; Continuing Education; Education; Higher Education; Higher Education Administration; Social Research; Teacher Education

Ph.D., Antioch University, 2020, Leadership and Change

Global Virtual Teams (GVTs) enable organizations to become more flexible, and to adapt and react to turbulent, complex and dynamic environments. These teams span boundaries such as space, time, and geography, working collaboratively to achieve a shared purpose. Due to their reliance on technology for communication, knowledge sharing, and project management, structural and nonstructural components of their design must exist to enable these teams to exist and flourish at the edge of innovation. The human experience of working in virtual teams remains insufficiently observed, yet crucial to their sustainability. This dissertation study employed an exploratory sequential mixed methods design to provide insights into the experience of working as a member or leader on a GVT. In phase one, a theoretical framework was developed to identify themes and sub-themes that emerged from 21 interviews with GVT practitioners from seven nations and multiple time zones across many sectors. The data revealed that experiences of working on a GVT are best expressed by four major themes: team design (both structural and nonstructural) components, cross-cultural communication, human dynamics, and technology. One meta-theme emerged, adaptability, which is well supported by the chosen guiding theoretical framework, adaptive structuration theory (AST), as well as extant research. The results of phase one informed development of a survey instrument; a pilot test of this instrument showed promise for future validation of a scale that accurately depicts the experiences of working on a GVT. The current findings support practical applications toward better understanding team functioning, essential human needs, and best practices for team awareness and functioning. This dissertation is available in open access at AURA: Antioch University Repository and Archive, http://aura.antioch.edu/and OhioLINK ETD Center, https://etd.ohiolink.edu/.

Committee: Jon Wergin PhD (Committee Chair); Aqeel Tirmizi PhD (Committee Member); Muriel Scott PhD (Committee Member) Subjects: Management; Organization Theory; Organizational Behavior; Social Psychology

Doctor of Philosophy, The Ohio State University, 2020, Mechanical Engineering

To improve the fuel economy and to reduce the emission in internal combustion (IC) engines, advanced engine technologies such as the homogeneous charge compression ignition (HCCI), further increasing the compression ratio, and gasoline engine downsizing with charge boosting need to be further developed. The development of these technologies is restricted by the prediction and control of the ignition of premixed fuel/air mixtures. The ignition of the premixed mixtures in IC engines is governed by complex chemical kinetics. The in-cylinder flow turbulence, temperature inhomogeneity, and other mixture conditions affect the ignition processes by influencing the chemical reaction rates. In this study, the conditional moment closure (CMC) method is extended for the ignition of the premixed mixtures with temperature inhomogeneity in IC engines. A CMC model based on sensible enthalpy is developed for the ignition of the premixed mixtures. Closure models for the mixing statistics of sensible enthalpy are proposed based on a mapping method. A method to couple the CMC model with a multidimensional flow solver for the prediction of knock in SI engines is developed. In the coupling, a method to reduce the computational cost by solving a subset of species in the flow solver is proposed. The sensible-enthalpy-based CMC model and a total-enthalpy-based formulation are assessed with data from 2-D direct numerical simulation (DNS) of the ignition of homogeneous primary reference fuel (PRF)-air mixtures with temperature inhomogeneity under HCCI conditions and spark ignition (SI) engine knocking conditions. Results show that the total-enthalpy-based CMC gives good predictions of the heat release rate (HRR) under HCCI conditions when the temperature inhomogeneity level is low, but leads to substantial overprediction under SI engine knocking conditions regardless of the thermal stratification levels. The sensible enthalpy formulation gives good predictions of the HRR for the igni (open full item for complete abstract)

Committee: Seung Hyun Kim Dr. (Advisor); Datta Gaitonde Dr. (Committee Member); Sutton Jeffrey Dr. (Committee Member); Shawn Midlam-Mohler Dr. (Committee Member) Subjects: Mechanical Engineering

PhD, University of Cincinnati, 2017, Engineering and Applied Science: Aerospace Engineering

Ceramic matrix composites (CMCs) are poised to revolutionize jet engine technology by enabling operation temperatures well beyond those possible with current superalloys, while reducing active cooling requirements and engine weight. Manufacturing of parts formed by silicon-carbide (SiC) fibers in a SiC matrix is now well advanced, with the first non-structural static components already in service in the CFM Leap engine. In order to expand the scope of application of CMCs to rotating parts, it is necessary to characterize the modes of failure of these materials at temperatures beyond 1100 C. In this context, the ability of nondestructively monitoring the formation and progression of damage in CMCs specimens during high-temperature mechanical testing is critical. Due to its excellent sensitivity and low cost, ultrasonic inspection is a well developed technique which allows to create accurate two and three-dimensional images of specimens by either mechanically scanning them or using phased array probes. However, the elevated temperature precludes use of traditional actuation techniques. In this context, the generation and detection of elastic waves using laser beams is an attractive possibility to characterize CMCs in a hostile environment with high sensitivity. In this work, the first experimental assessment of the feasibility of noncontact laser ultrasonic inspection of SiC/SiC flat coupons is presented. An Nd:Yag laser is used to excite ultrasonic waves on one side of the specimen while a Michelson interferometer detects the signals emerging on the other side at the epicenter position. The lasers are mounted on synchronized linear stages to form C-scans as in conventional immersion ultrasonics while ablation damage to the surface of the specimen is prevented by operating the lasers at low power density. It is shown that it is possible to image interlaminar defects caused by impacts and monitor crack opening under tensile load. Finally, very go (open full item for complete abstract)

Committee: Francesco Simonetti Ph.D. (Committee Chair); San-Mou Jeng Ph.D. (Committee Member); Aaron Sellinger Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science in Materials Science and Engineering (MSMSE), Wright State University, 2016, Materials Science and Engineering

SiC/SiC ceramic matrix composites (CMCs) with potential applications at =2700°F (1482°C) are of significant interest to the Air Force. The high temperature performance of SiC fibers used within these composites is greatly affected by the presence of amorphous SiOC and free carbon in the fibers. Therefore quantification of this non SiC material in commercially available SiC fibers is extremely important. In this work Hi Nicalon, Hi-Nicalon Type-S, Tyranno-SA3, Cef-NITE, and Sylramic SiC fibers were studied. Changes in mass, grain size, and amorphous content were measured as a function of processing temperature and time. The amorphous material in each fiber was quantified using the Spike-In method in conjunction with Rietveld refinement. Trends in amorphous content were observed, as well as trends in grain size and crystallized fraction. Transmission electron microscopy (TEM) was used to confirm changes in fiber microstructure.

Committee: H. Daniel Young Ph.D. (Advisor); Hong Huang Ph.D. (Committee Member); Michael Cinibulk Ph.D. (Committee Member); Robert E. W. Fyffe Ph.D. (Other) Subjects: Aerospace Materials; Materials Science

Doctor of Philosophy, University of Toledo, 2015, Curriculum and Instruction

The proliferation of online simulation games across the globe in many different languages offers Computer Assisted Language Learning (CALL) researchers an opportunity to examine how language learning occurs in such virtual environments. While there has recently been an increase in the number of exploratory studies involving learning experiences of predominantly English as a Second or Foreign Language (ESL/EFL) participants in these environments, the context of a Japanese as a Foreign Language (JFL) classrooms has rarely been examined. To address this, this study investigates a Second Language Acquisition-theory driven instantiation of CALL within the context of a JFL classroom. Through a mixed-method case study approach, participants' natural acquisition of Japanese in a 3D virtual environment was examined. Data detailing participants' communicative capacities in several modalities were collected, as were their attitudes toward participation in a massively multiplayer online (MMO)-based virtual world of Tokyo. In the present study, eight sources of data from eleven university-level JFL students (n=11) were collected and analyzed to evaluate the learning outcomes from an integrative CALL framework (Warschauer, 2004; Yamazaki, 2014). Based on both interpretative and statistical analyses of data, the major finding of the present study was that the participants, when immersed in the 3D virtual world of Tokyo, acquired contextualized communicative competence. More specifically, quantitative analyses revealed statistically significant improvement in the participants' acquisition of incidentally encountered vocabulary, in particular, kanji pronunciation and vocabulary interpretation. Qualitative analyses revealed participants' acquisition of various communicative competencies specific to the context, including persuasive talk, concept of audience, collaborative communication, and colloquial expressions. Data from a post-hoc reflection survey provided strong evidence (open full item for complete abstract)

Committee: Susanna Hapgood (Committee Chair); Leigh Chiarelott (Committee Member); Douglas Coleman (Committee Member); Florian Feucht (Committee Member) Subjects: Curricula; Curriculum Development; Educational Technology; Instructional Design; Language

Master of Arts, Case Western Reserve University, 2015, Cognitive Linguistics

This thesis expands and applies Shifman's (2013) communication oriented typology for memes and uses conceptual blending theory to show that the “Keep Calm and Carry On” internet meme is altered in predictable patterns. Based on this analysis, we conducted a survey study seeking to answer: 1. How do the dimensions of the taxonomy work together in order to create humor and understanding? 2. What is the minimal number of changes that can be made to a parody while still allowing it to make sense? 3. Does how well a person “gets” an internet meme predict humor ratings? The results indicate that people's ratings of funniness are highly dependent on whether or not the person feels they have understood or “gotten” the meme. Beyond this, the results varied widely between the memes studied and tended to fall into six distinct categories based on whether or not participants “got” the meme.

Committee: Fey Parrill (Committee Chair); Mark Turner (Committee Member); Vera Tobin (Committee Member) Subjects: Cognitive Psychology; Linguistics

Master of Science in Engineering, University of Akron, 2014, Mechanical Engineering

Ceramic matrix composites (CMC) composed of Hi-Nicalon Type S™ fibers, a boron-nitride (BN) interphase, and pre-impregnated (pre-preg) melt-infiltrated silicon / silicon-carbide (SiC) matrix have been studied at room-temperature consisting of unidirectional and cross-ply laminates. Quasi-static, hysteretic and uniaxial tensile tests were done in conjunction with a variety of temporary, laboratory-based material health-monitoring techniques such as electrical resistance (ER) and acoustic emission (AE). The mechanical stress-strain relationship paired with electrical and acoustic measurements were analyzed to expand upon current composite knowledge to develop a more fundamental understanding of the failure of brittle matrix laminates, their constituents, and interactions. In addition, a simple but effective method was developed to allow visual confirmation of post-test crack spacing via microscopy. To enhance fidelity of acquired data, some specimens were heat-treated (i.e. annealing) in order to alter the residual stress state. Differences in location, acoustic frequency, and magnitude of matrix cracking for different lay-ups have been quantified for unidirectional and [0/90] type architectures. Empirical results shows complex hysteretic mechanical and electrical behavior due to fiber debonding and frictional sliding of which no general model exists to capture the essence of this CMC system. The results of this work may be used in material research and development, stress analysis and design verification, manufacturing quality control, and in-situ system and component monitoring.

Committee: Gregory Morscher Dr. (Advisor); Wieslaw Binienda Dr. (Committee Member); Tirumalai Srivatsan Dr. (Committee Member) Subjects: Aerospace Materials; Mechanical Engineering

Doctor of Philosophy (Ph.D.), University of Dayton, 2014, Materials Engineering

Coiled carbon filaments have one of the most attractive three-dimensional forms in carbon materials due to their helical morphologies. Because of their shape and carbon structure, they exhibit excellent mechanical and electrical properties such as superelasticity, low Young's modulus, relatively high electrical conductivity, and good electromagnetic (EM) wave absorption. Therefore, they are good candidates as fillers in composite materials for tactile sensor and electromagnetic interference shielding. In medical areas of interests, coiled carbon filaments can be used as micro and nano heaters or trigger for thermotherapy and biosensors using EM wave exposure because absorbed EM waves by coiled carbon filaments are converted into heat. Although various shapes of coiled carbon filaments have been discovered, optimum synthesis conditions and growth mechanisms of coiled carbon filaments are poorly understood. The study of growth kinetics is significant not only to analyze catalyst activity but also to establish the growth mechanisms of coiled carbon filaments. The establishment of growth mechanisms would be useful for determining optimum synthesis conditions and maximizing the quantity of carbon filaments synthesized for a given application. In the first study, tip grown single helical carbon filaments or carbon nanocoils (CNCs) were synthesized by a chemical vapor deposition method using tin-iron-oxide (Sn-Fe-O) xerogel film catalyst. The Sn-Fe-O catalyst was prepared by a low-cost sol-gel method using stannous acetate and ferric acetate as precursors. The growth kinetics of CNCs were monitored by a thermogravimetric analyzer, and the experimental result was correlated using a one-dimensional kinetic model, corresponding to one-dimensional tip growth. In the second study, bidirectionally grown double helical filaments or carbon microcoils (CMCs) were synthesized using a chemical vapor deposition method. CMCs obtained at two reaction temperatures were compared (open full item for complete abstract)

Committee: Khalid Lafdi (Committee Chair); C. William Lee (Committee Member); Donald Klosterman (Committee Member); Tsonis Panagiotis (Committee Member); Usman Muhammad (Committee Member) Subjects: Materials Science

Master of Applied Communication Theory and Methodology, Cleveland State University, 2014, College of Liberal Arts and Social Sciences

This paper is designed to explore how online readers process information when online news articles have majority cues. These majority cues are conceptualized as a specific type of heuristic cue and this study discovered complex interaction effects of this heuristic cue. Heuristic and Systematic Model (HSM) and Elaboration Likelihood Model (ELM) successfully predict how these interaction effects work when these models work together. MANOVA and ANOVA analyses report significant interaction effects among heuristic cues, involvement, and argument quality on readers attitudes (attitude toward information and author's credibility) that supporting both Hypothesis 1 and 2. Specifically, in regard a Hypothesis 1, when argument quality is strong the heuristic cue increases the attitude toward information and author's credibility more positively when the information is about a low-involvement product. On the other hand, the heuristic cue decreases attitude toward information and author's credibility more negatively when the information is about a high-involvement product. Regarding a Hypothesis 2, when the heuristic cue is low, the strong argument quality increases the attitude toward information and author's credibility more positively when the information is about a high-involvement product. On the other hand, the strong argument quality decreases the attitude toward information and author's credibility more negatively when the information is about a low-involvement product. In summary, the explanations of both HSM and ELM are supported only when people use their cognitive resources efficiently. On the other hand, theories of Maximization of Cognitive Efficiency (MCE) and affordances explain when people need to use cognitive resources inefficiently. That is because humans are naturally moderate their information processing in the dynamic manner that maximizes their cognitive efficiency to interpret the given information and environment efficiently and in a timely manne (open full item for complete abstract)

Committee: EDWARD HOROWITZ Ph.D. (Committee Chair); CHERYL BRACKEN Ph.D. (Committee Member); GARY PETTEY Ph.D. (Committee Member) Subjects: Communication; Information Science; Journalism; Mass Communications; Mass Media; Multimedia Communications

PhD, University of Cincinnati, 2007, Arts and Sciences : Chemistry

Pseudouridine, the most abundant post-transcriptional modification in RNA, was derivatized with the water-soluble carbodiimide, N-cyclohexyl-N'-a-(4-methylmorpholinium) ethylcarbodiimide (CMC). Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was utilized as the mode of detection for CMC-derivatized pseudouridine. Initial studies involving method optimization were conducted on a simple homopolymer and heteropolymer DNA system. These studies were directed toward optimizing the CMC derivatization reaction conditions and ensuring its compatibility with MALDI-MS. After optimization, the method was applied to the determination of pseudouridine in a small RNA, Escherichia coli tRNATyrII. In addition to pseudouridine, this work revealed that the post-transcriptionally modified nucleoside, 2-methylthio-N6-isopentenyladenosine (ms2i6A) was also susceptible to derivatization by CMC. Method application studies were further expanded to include the detection of pseudouridines in a complicated mixture of E.coli tRNAs. For the complex mixture of tRNAs, endonuclease mapping and a signature digestion product approach was implemented with the CMC derivatization / MALDI-MS method for accurate identification and sequence placement of pseudouridine to individual tRNAs in the mixture. Further studies included the application of the CMC derivatization / MALDI-MS method for pseudouridine detection in a large RNA. Preliminary data was also generated from an affinity purification based approach for the detection of CMC derivatized oligonucleotides. These studies reveal the potential utility of the CMC derivatization / MALDI-MS approach as a fast and facile method for screening for pseudouridine in RNA.

Committee: Dr. Patrick Limbach (Advisor) Subjects: Chemistry, Analytical

PhD, University of Cincinnati, 2004, Arts and Sciences : Chemistry

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an important tool for high throughput analysis in the field of genome mapping, medical diagnostics and protein identification. Though it is the best option for rapid complex mixture analysis, it does suffer from ion suppression effects, which depend on the type of analytes in the mixture and the sample preparation techniques. The goal of this dissertation is to develop surfactant-aided MALDI-MS (SA-MALDI-MS) for the characterization of complex mixtures and to understand the role of the surfactant in such analyses. Critical micellar concentrations (CMC) of sodium dodecylsulfate (SDS), 0.1%-0.3% w/v, were found to be optimal for SA-MALDI-MS of complex mixtures. The presence of micelles was confirmed by surface tension experiments. To determine the role of these micelles, interactions between SDS and peptides of varying hydrophobicities were studied by fluorescence. Further, SA-MALDI-MS was used in peptide mass fingerprinting, modification mapping and serum profiling experiments to demonstrate the versatility of this technique. Peptide mapping experiments were performed on model proteins using MALDI and SA-MALDI MS. From these experiments it was found that on addition of SDS prior to MALDI analysis there was an increase in the number of tryptic peptides detected thereby improving the total sequence coverage of the analysis. It was found that interactions between peptides and SDS micelles depended on peptide hydrophobicity, sequence, size and charge. In an approach to determine the sites of interactions between MSP and other oxygen-evolving protein complex, chemical protection assays were used to label MSP, and SA-MALDI-MS along with sample fractionation were used to increase sequence coverage from peptide mapping experiments to identify sites of chemical modification. SA-MALDI-MS was also investigated as a sample preparation approach for serum protein profiling. Various clean-up methods were us (open full item for complete abstract)

Committee: Dr. Patrick Limbach (Advisor) Subjects:

Master of Arts, University of Toledo, 2010, English (as a Second Language)

This thesis explores language and gender on Facebook. A discussion board on a popular Facebook group is the focus of the study. 19 topic threads from the discussion board were examined. The first theme that I identified in the data is that males made disruptive statements in discussions. Next, males were more likely than females to attack other participants through the use of sarcasm and name calling, often using harsh and aggressive name calling. Although some females utilized personal attacks in discussions, they were more likely to criticize another participant's grammar. Females also used grammar corrections to facilitate relationships. Additionally, female participation was low in discussion threads that contained many arguments and attacks. Females seem to be more engaged in topics where arguments did not take place such as topics devoted to game board discussions where conflict was low. Limitations of the research are discussed and suggestions for future research are offered.

Committee: Melinda Reichelt Dr. (Committee Chair); Amy Capwell-Burns Dr. (Committee Member); Anthony Edgington Dr. (Committee Member) Subjects: Gender; Language; Linguistics; Mass Media; Womens Studies

Master of Arts, The Ohio State University, 2011, Communication

Computer-mediated communication (CMC) research has long been interested in how interpersonal impressions form online. This research argues that, given the advance of technology and the diversity in online environments, researchers must now consider the context in which social information appears in order to more fully understand the effects of social information on impression formation. This study found, in hypotheses based on correspondent inference theory (Jones & Davis, 1965) and the hyperpersonal model (Walther, 1996), that the context of a website impacts credibility impressions. An original 2 (valence of photograph: casual vs professional) x 2 (normative context: WebMD vs Facebook) experiment examining the impact of moving identical cues across contexts found normative expectations impact impression formation. In particular, this experiment assessed how observers judge a doctor's credibility and task-attractiveness based on whether they saw a normative or non-normative picture for the context of the website in which they are presented. Findings indicate support for a non-normativity effect: cues that defied normative expectations were more influential. Based on these findings, it is concluded that a non-normativity effect, based on expectations of the type of information for a specific context, drives the other effects.

Committee: Brandon Van Der Heide PhD (Advisor); Kelly Garrett PhD (Committee Member); Jesse Fox PhD (Committee Member) Subjects: Communication

Master of Arts, The Ohio State University, 2010, Communication

Just as visual cues influence our face-to-face conversations and behavior during cross-cutting political discussions, visual cues in computer-mediated communication (CMC) are hypothesized to do the same. The research presented here assesses the impact of visual cues offered by avatars on perceived source credibility, willingness to engage in cross-cutting political discussion, and reevaluation of a counter-attitudinal political idea. A 2x3 experiment revealed that there were no significant differences in credibility ratings, willingness to engage in cross-cutting political conversation, and reevaluation between those who interacted with a avatar high in human realism, one low in human realism, and no avatar. However, there was a significant interaction between the textual credibility of a message and the decision to reevaluate a counter attitudinal political idea when an avatar was present. These results indicate that when an avatar is present, cues to message credibility become more important in determining reevaluation. Implications for cue processing in CMC and future research are discussed.

Committee: R. Kelly Garrett PhD (Advisor); Brandon Van Der Heide PhD (Committee Member) Subjects: Communication; Political Science; Psychology