Being gay and being overweight are two stigmatized statuses in the United States. A range of work has considered the experience of being stigmatized and the consequences of stereotypes for overweight individuals and sexual minorities, but less research has examined the intersection of these two stigmas among larger gay men or collective efforts to resist such stigma. This dissertation extends this work by examining the joint consequences of being a sexual minority and having body dissatisfaction for men using a mixed methods design. In the first study, I contrast young gay men's weight dissatisfaction with that of heterosexual men to demonstrate the heightened risk of depression for overweight gay men using nationally representative data. But stigmatized individuals are not passive in their experience of weight and sexual orientation stereotypes. The second study qualitatively examines a subculture of gay men, the bears, to test theoretical models of stigma resistance. The results demonstrate the transferability of stigma resistance among multiple stigmatized attributes and the use of multiple strategies to resist one stigma. At the same time, it shows how subcultural dynamics both aid and undermine the resistance toward stigma, and the risk of reinforcing stigma's effect through criticizing others who embody a stereotype. The results also demonstrate how resistance strategies are both empowering and psychologically taxing for stigmatized individuals. / A Dissertation submitted to the Department of Sociology in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / August 31, 2012. / body image, gender, sexuality, stigma, stigma resistance, subculture / Includes bibliographical references. / John Reynolds, Professor Directing Dissertation; Jasminka Illich-Ernst, University Representative; Douglas Schrock, Committee Member; Koji Ueno, Committee Member.

The invention of the steamship had a widespread effect on both the world of trade and military conflict. However, current scholarship does not give sufficient credit to how important this piece of technology was. While not the sole cause of victory in colonial warfare, nor a guarantee of victory, the steamship was an indispensable tool in the expansion of colonialism in the 19th century. Allowing for the tactics of gunboat diplomacy, lightning fast wars, and vast improvements in logistics, the path of European colonialism was shaped by the steamship. In the Anglo-Burmese Wars, First Anglo-Sino War, and the Perry Expedition steamships were used to great effect in gaining favorable concessions and terms of trade for Europeans. Specifically, steamships allowed European forces to penetrate far further inland than was previously possible. Without such penetration, the large, centralized capitals of Ava, Peking, and Edo could not be threatened. Facing political challenges at home, the humiliation and danger of submission to foreign will had to be balanced by sufficient threat to these governments' very seats of power. Connected to this was improvements in logistics and the health of troops would see the cost of conducting these wars to a point of cost-effectiveness necessary. These conflicts were largely undertaken in an attempt to create new sources of revenue for European countries, and the steamship was invaluable in reducing the cost of waging war to an acceptable level. Lack of political unity and centrally located governments on the Asian side increased the efficacy of steamships. While not an immutable guarantee of victory, the steamship molded the type of imperialism seen and thus the world we know today. / A Thesis submitted to the Program in Asian Studies in partial fulfillment of the requirements for the degree of Master of Arts. / Fall Semester, 2012. / October 25, 2012. / First Anglo-Burmese War, First Anglo-Sino War, Perry Expedition, Second Anglo-Burmese War, Steamships, Technology in colonialism / Includes bibliographical references. / Jonathan Grant, Professor Directing Thesis; Claudia Liebeskind, Committee Member; Charles Upchurch, Committee Member.

Merrill (2002a) created a set of fundamental principles of instruction that can lead to effective, efficient, and engaging (e3) instruction. The First Principles of Instruction (Merrill, 2002a) are a prescriptive set of interrelated instructional design practices that consist of activating prior knowledge, using specific portrayals to demonstrate component skills, application of newly acquired knowledge and skills, and integrating the new knowledge and skills into the learner's world. The central underlying principle is contextualizing instruction based on real-world tasks. Merrill (in press) hypothesizes that if one or more of the First Principles are not implemented, then a diminution of learning and performance will occur. There are only a few studies that indicate the efficaciousness of the First Principles of Instruction. However, most claims of efficacy in the application and usage of the principles are anecdotal and empirically unsubstantiated. This phenomenon is not isolated to the First Principles of Instruction. Claims of effectiveness made by ISD model users have taken precedence over empirically validating ISD models. This phenomenon can be attributed to a lack of comprehensive model validation procedures as well as time restraints and other limited resources (Richey, 2005). Richey (2005) posits that theorists and model developers tend to postulate the validity of a model due to its logicality and being supported by literature, as is the case with the First Principles of Instruction. Likewise, designers tend to equate the validity of a model with an appropriate fit within their environment; that is, if using the model is easy, addresses client needs, supports workplace restraints, and the resulting product satisfies the client then the model is viewed as being valid (Gustafson & Branch, 2002; Richey, 2005). Richey and Klein (2007) emphasis the importance of conducting design and development research in order to validate the use of instructional design models, which includes the fundamental principles (e.g., First Principles of Instruction) that underlie instructional design models. These principles and models require research that is rigorous and assesses the model's applicability instead of relying on unsubstantiated testimonials of usefulness and effectiveness (Gustafson & Branch, 2002). In order to validate the use of principles and models researchers need to explore and describe the usage of the principles and models to determine the degree of implementation in different settings (Richey & Klein, 2007). The purpose of this study was to examine the use of the First Principles of Instruction (Merrill, 2002a) and the decisions made by instructional designers --including project leads, team leads, and designers-by-assignment. The investigation of the use of the First Principles was part of an effort to determine if these principles were conducive to being implemented during a fast-paced project that required the design and development of a large number of online modules. The predominant research question for this study was: How were the First Principles of Instruction used by instructional designers, in a short-term, high volume, rapid production of online K-12 teacher professional development modules? Four supporting questions were also addressed: 1) What were the conditions under which the First Principles of Instruction were used? 2) What design decisions were made during the project? 3) What is the level of understanding of the First Principles by instructional designers? 4) How frequently do the modules incorporate the First Principles of Instruction? This case study involved 15 participants who were all instructional designers and designers-by-assignment that worked on 49 science and math professional development modules for K-12 teachers within a short 11-week time period. Participant interviews, extant data --project management documents, e-mail communications, personal observations, recordings of meetings, participant surveys, and the evaluation of nine online modules consisted of the data collected in this design and development research study. The results indicated the First Principles of Instruction were not used at the level expected by the lead designer and may not be conducive to being applied as described by Merrill (2002a, 2007a, 2009a, 2009b) in this case. The frequency of use of the First Principles in the modules showed an overuse of the Activation/Tell principle in relationship to the number of Demonstrations/Show and Application/Ask applications. Results also indicated that the project requirements, personnel, designer experience, the physical setting, and training and meetings contributed to decision-making and ultimately to the use and misuse of the First Principles of Instruction. / A Dissertation submitted to the Department of Educational Psychology and Learning Systems in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / August 1, 2012. / Design and Development Research, First Principles of Instruction, Instructional Design Theories and Models, Instructional Systems Design, Online Learning, Task-centered Instruction / Includes bibliographical references. / Tristan E. Johnson, Professor Co-Directing Dissertation; James D. Klein, Professor Co-Directing Dissertation; Jonathan Adams, University Representative; Vanessa P. Dennen, Committee Member.

The oboe reed is both a blessing and a curse--the bane and the delight of every oboist. There is nothing greater than the satisfaction of creating an amazing reed that will do everything an oboist requires. A great reed allows one to play for hours and not grow exhausted. It helps produce easier articulation and response from the instrument, as well as a better musical line to help the oboist sound more fluid in his phrasing. A bad reed, however, will cause a lot of stress in the life of an oboist, forcing him to spend countless hours behind a reed desk. Due to the uniqueness of each reed and each oboist, no two players will ever produce an identical tone on the oboe. This is true even if two players use the same oboe with the exact same reed. The whole purpose behind reed making is not to create another level of difficulty for the oboist, but to uniquely bring out the best qualities of the oboe and the oboist's individuality. Reed making, while stressful in the early stages of learning, eventually becomes a very personal endeavor for each oboist. The more knowledge gained in the reed-making process, the greater the strive to perfect it. In reality, there is no such thing as a perfect reed. An oboist's goal, when making reeds, is to strive for response, correct pitch, stability, and a tone that is unwavering in beauty. The tone should not be so strident and shrill that it lacks depth, yet also not be so dark that the flexibility of the tone is hindered. As the majority of reed making taught today is based on the American style of reed making, few students get the opportunity to learn about reed making from the Philadelphia point of view. Most do not even realize the school of reed making they learn from is derived from the Philadelphia style. There are many guides already published and available for oboists today, but none refer to the oboe reed through the Philadelphia influence. This paper is not meant to state the Philadelphia reed-making process is the only correct way to make a reed. It is intended to enlighten young and professional oboists and to tweak their interest in experimenting with their own reeds to create an even better product. It is the goal of this project to present ideas of reed making to both amateur and professional oboists, who have not had the opportunity to study within the aforementioned Philadelphia music schools. It will allow them to take a look at their current reed-making skills and apply new ideas. One of the most beautiful aspects of reed making is that it is constantly changing. It is my hope that the information provided in this document, and supplied from other oboists influenced by the Philadelphia style, will open new reed-making ideas to many oboists. This document will contain all information I have accumulated in the years of study in Philadelphia and present the knowledge of reed making through my eyes. It will follow the process of reed making from raw materials through the finished reed, and discuss each detail that goes into creating the Philadelphia reed. Surveys on reed making, from other graduates from the Philadelphia area, are included in this study to serve as reinforcement to the ideals and principles that still hold true in the Philadelphia area today. Reed making has always been one of my strongest passions as an oboist and it is my wish to share the knowledge I have obtained throughout my years of study. / A Treatise submitted to the College of Music in partial fulfillment of the requirements for the degree of Doctor of Music. / Fall Semester, 2012. / September 27, 2012. / Oboe, Philadelphia, Reed / Includes bibliographical references. / Eric Ohlsson, Professor Directing Treatise; Richard Clary, University Representative; Deborah Bish, Committee Member.

Current educational reform efforts are focused on enhancing school and teacher accountability as a means of improving student learning. One policy initiative resulting from these efforts is the inclusion of outcome-based teacher performance (OTP) as a component of teacher evaluations. OTP is defined as a teacher's contribution to the learning outcomes of her students. An increasingly popular method for measuring OTP is a set of statistical techniques known as value-added models (VAMs). Despite their popularity, the validity of VAM estimates of OTP has not been fully established. This dissertation contributes to the ongoing validity debate by evaluating the construct validity of VAM estimates. Specifically, construct validity is evaluated by examining the theory of the process by which teachers contribute to student learning that is implicit to VAM estimation of OTP. Embedded within each VAM is a set of theoretical implications about the teaching-learning process. In addition, the identifying conditions necessary for the estimation of OTP from observational data impose restrictions on the teaching-learning process and therefore have theoretical implications. Evaluation of these implications indicates that most are inconsistent with theoretical, empirical, and logical evidence how teachers contribute to student learning outcomes. This evidence weakens the validity of the claim that VAMs can be used to measure OTP. The degree to which this claim is weakened, however, remains a question for future research. / A Dissertation submitted to the Askew School of Public Administration and Policy in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / July 30, 2012. / Assumptions, Production Function, Teacher Performance, Teaching-Learning Process, Value Added Models / Includes bibliographical references. / Robert J. Eger, III, Professor Co-Directing Dissertation; Lance deHaven-Smith, Professor Co-Directing Dissertation; Carolyn Herrington, University Representative; Alysia Roehrig, Committee Member; Anastasia Semykina, Committee Member.

This dissertation describes spin injection, transport, and detection experiments from Fe electrodes into a bulk AlGaAs channel. This semiconducting alloy is one of a class of persistent photoconductors, chosen as the spin transport medium because its carrier density can be tuned in a controlled manner via photoexcitation through the metal to insulator transition (MIT) in situ. This allows one to determine the dependence of spin lifetime on a variety of external parameters including carrier density, all on one sample. This research represents the first electrical spin-dependent measurements in this material and describes the dependence of the Hanle signal size and spin lifetime on bias, temperature, and carrier density. The photoexcitation needed to change the carrier density in this material comes from an infrared light-emitting diode (IR LED). The first step of this project was to characterize the new, highly Si doped Al0.3Ga0.7As heterostructures, in order to determine how the illumination of the sample will affect the parameters of the material. To complete this study, Hall crosses were fabricated from the AlGaAs material and the transport properties were measured between 350 mK and 165 K. The resistivity, carrier density, and mobility were determined as a function of temperature for a variety of different illumination times. From this data, the MIT, scattering mechanisms, and the shape of the band tail of the density of states (DOS) were investigated. In fact, this is the first work to electrically probe the DOS in AlGaAs. Once the materials were characterized, they were used to fabricate lateral spin transport devices. Spin transport and accumulation were studied in detail via Hanle effect measurements, which measure the dephasing of electron spins in a perpendicular magnetic field. From these measurements, the spin lifetime of the material can be calculated, and is in the nanosecond range for all measured carrier densities. The spin lifetimes are measured using three distinct measurement configurations which all give consistent results. The dependence of spin lifetime and Hanle signal size are reported as a function of bias, temperature, and carrier density. This is the first spin transport experiment using a persistently photoconductive material as the spin transport channel in order to change the carrier density of the material in situ. The research in this dissertation successfully provides a framework for the continuation of spin injection and detection studies in this and other alloy semiconductors, and provides insight into how the spin lifetime depends on the doping levels in semiconductors. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / August 17, 2012. / AlGaAs, density of states, metal-insulator transtion, spin accumulation, spin injection, spin transport / Includes bibliographical references. / Stephan von Molnár, Professor Directing Dissertation; Albert Stiegman, University Representative; Peng Xiong, Committee Member; Nicholas Bonesteel, Committee Member; Jorge Piekarewicz, Committee Member.

The purpose of this study was to determine the feasibility of Piano WizardTM as a viable technological and instructional tool for older adults. Piano Wizard's applicability for seniors was determined by participants' musical skill development, perceptions of personal fulfillment, attitudes toward music learning, and opinions about the software program Piano WizardTM. Secondary purposes of the study were: (1) to identify participants' motivation for enrolling in a music skills program and (2) to examine differences in participants' attitudes, perceptions, and skill development based on their: age, previous musical experience, socio-economic status, or participation in individual vs. partner lessons. Six 30-minute weekly sessions were offered to residents at two retirement communities of contrasting socio-economic status (SES). Thirty older adults volunteered to serve as participants, and twenty-five (N=25) completed the six weeks of instruction. Musical skill development was determined by participants' average accuracy scores, the number of pieces learned, and `song-level' achieved at the end of the six weeks. Results revealed that participants met two of the three pre-determined criteria indicating musical progress, and that there were no significant differences in musical skill development based on participants' previous musical experience, SES, or participation in individual vs. partner lessons; however, significant differences were found based on participants' age. Older participants achieved significantly lower accuracy scores, learned significantly fewer songs, and achieved significantly lower song levels than younger participants. Participants' perceptions of personal fulfillment were examined using a questionnaire, with "escape from routine" and "play and fun" ranked as the highest-rated benefits of the lessons. Ratings of social benefits were not significantly different between participants taking individual and partner lessons. Attitudes toward music learning were measured through participants' weekly journals. Analysis of journal entries revealed a ratio of approximately 7:1--positive to negative comments concerning the Piano WizardTM program and the piano lessons. Almost three-fourths of the participants reported that they would continue lessons using Piano WizardTM if given the opportunity, with indicated partiality towards the rich accompaniment, colored notation, and multi-sensory features of the program. The highest ranked reason for participating in lessons was "to expand my mind." Although further research is warranted, the findings of this study suggest that Piano WizardTM is a viable technological and instructional tool for older adults wishing to study piano. / A Dissertation submitted to the College of Music in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / October 23, 2012. / adult music education, computer assisted instruction, music and older adults, piano technology / Includes bibliographical references. / Alice-Ann Darrow, Professor Co-Directing Dissertation; Vicki McArthur, Professor Co-Directing Dissertation; Larry Gerber, University Representative; Judy Bowers, Committee Member; John Geringer, Committee Member.

We studied H-shell flashes on CO WDs accreting Hydrogen rich matter in regimes where they are believed to be on the border of stable accretion and of having dynamical mass loss. These systems are believed to be progenitors of SNe Ia, however, there is still some question of what range of accretion rates and WD masses allow for growth to the Chandrasekhar mass, if any do at all. Flashes that result in mass loss are also of interest as they enrich the Inter Stellar Medium. Initial models are calculated using a stationary evolution code that starts with a 0.5 M WD. Accretion of material of solar metalicity is employed, and nuclear burning is allowed, until the model reaches the desired masses of 0.8 M and 1.0 M for our study. The resultant initial models have structures that are in agreement with the previous works of [93, 26, 96] for accreting hot WD models. The flashes were calculated with an explicit hydrodynamics code that utilizes the PPM method, a second order Godunov scheme, allowing for high time resolution during the flash. This code is used in the co-moving frame to avoid chemical advection over time. Due to a recurrence of flashes of years to thousands of years, however, periods of steady nuclear burning were evolved in a quasi-static method, allowing for longer time steps than are possible in an explicit hydro code. Thus, evolution of the models followed an alternating quasi-static/explicit hydro evolution scheme until flash conditions were met, at which point the explicit hydro was employed. Use of an explicit hydro code has allowed for the observation of a new physical effect from wave dissipation. With our high time resolution, energy transport via waves, and detailed EOS, we found that at the onset of the flash, a reduction in the degeneracy pressure due to electron captures, results in a reduction of the total pressure. With a gravitational acceleration on the order of 108 in the shell, a reduction of the total pressure by 1% results in an in fall acceleration of 10 km . With such a strong in fall, compressional heating results in a hotter flash, with results showing temperatures over a billion degrees in all models. These high temperatures had consequences on the nucleosynthesis, as they allowed for rp-breakout during the flash. The effect of a "double" flash was found in one model. This resulted when the flash stalled in the H-shell, resulting in high temperature burning in only a portion of the shell. Once the H was exhausted in the flash region, cooling occurred and there was contraction of the H exhausted region. This contraction caused an in fall of the un-exhausted region which via compressional heating resulted in the flash to occur in the un-exhausted region. Such an effect may happen in any progenitor system in which the flash stalls and compression afterwards is suitable for a re-start of the flash. This effect may be observable with the current generation of instruments. With the high temperatures found in the flashes, rp-breakout nucleosynthesis was found to occur. Occurrence of rp-nucleosynthesis in these objects may make important sources of the chemical enrichment of isotopes below the iron group that are not know to be synthesized in hydrostatic stellar burning. The existence of rp-breakout in the flashes, shows the importance of nuclear physics in these objects. More precise nuclear reaction rate data are needed for proper energy generation and chemical evolution. With the occurrence of rp-nucleosynthesis in our models, it is especially advantageous to study radioactive proton rich nuclei. These studies are not without many difficulties in the laboratory, as many of the studies require the use of low intensity radioactive beams making clean, high statistic studies difficult. To address this issue, the hybrid target technique was used. This target technique was found to be a great tool for studying resonant proton scattering with exotic beams. It has been used to measure elastic and inelastic excitation functions in the study of 8 B via 7 Be+p scattering, as well as 12 N+p elastic scattering. With such success, the hybrid target technique can be a very useful tool for studying reactions that are important in the rp-process. We have studied the structure of the astrophysically important, radioactive isotope 8 B. Three new resonances have been suggested, a 0+ , 2+ , and 1+ which were predominantly in the inelastic channel and never before seen in previous studies. However, due to their high excitation energies and narrow width, none of the resonances are expected to effect the astrophysically important 7 Be(p,γ) reaction rate. Results were compared to continuum shell model as well as ab initio calculations and found to be in good agreement with both sets of predictions, with the notable exception of the 2+ state. The structure of 13 O, an isotope important in the pp-chain breakout was studied by 12 N+p elastic scattering. This work extended the 13 O excitation function to higher energies than the previous work of [120], however, the cross section was found to be rather flat. Due to the very low intensity of the radioactive 12 N beam, the experiment had very low statistics, 1+ making the observation of any states other than the known 2 very difficult. / A Thesis submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2012. / September 4, 2012. / Includes bibliographical references. / Peter Hoeflich, Professor Directing Thesis; Grigory Rogachev, Professor Directing Thesis; Munir Humayun, University Representative; Christopher Gerardy, Committee Member; Alexander Volya, Committee Member; Ingo Wiedenhover, Committee Member.

While access to images in general has improved in the last 20 years, due to both advances in electronic storage and dissemination and to improvements in the intellectual provisions of them, access to editorial cartoons lags behind access to other types of images. While there have been piecemeal or ad hoc efforts to organize large cartoon collections, these efforts have been based on the wants and needs of the organizers, publishers, or collectors. The purpose of this research was to gather information about user's descriptions of editorial cartoons. Specifically, it gathered terms and phrases provided by users to describe a set of editorial cartoons, both in an image tagging environment and in a simulated query environment. The population for this research was a blended sample; one population consisted of academics in fields that were assumed to have an interest in the research itself, and who were seen as likely to give a full, rich description of each image. The second population consisted of non-degree holding participants, against which the first results could be compared. The images used in this study were political cartoons from the five most recent Pulitzer Prize-winning editorial cartoonists. Content analysis of the cartoons' descriptions placed each description into one of Jörgensen's 12 Classes of image description, and the frequencies of each Class in this study were compared to similar studies. The results of this research show that while editorial cartoons can be described using Jörgensen's 12 Classes, they are described in very different ways than are other images. It was found that the Class ABSTRACT CONCEPTS was far more dominant when describing and searching for editorial cartoons than was so for other types of images; the Class LITERAL OBJECT was dominated by the attribute Text in both scenarios; VIEWER REACTIONS play a far larger role for these images than for others; and four Classes that are at least somewhat useful in searching for other types of images were almost unused when searching for editorial cartoons. Demographic variables show major differences in behavior among those of different education levels in tagging, and among different political views and genders when querying. Confirmatory interviews with image professionals and editorial cartoonists showed that the results would be of some use when implemented in the field. The results of this research would help inform efforts to index any image where the meaning of it was more important than the image content, and may help to describe all types of non-textual records of history and commentary. / A Dissertation submitted to the School of Library and Information Studies in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester, 2013. / January 16, 2013. / Communication and the arts, Editorial cartoons, Hstorical documents, Image description, Images, Metadata, Political cartoons / Includes bibliographical references. / Corinne Jörgensen, Professor Directing Dissertation; Lois Hawkes, University Representative; Michelle Kazmer, Committee Member; Paul Marty, Committee Member; Besiki Stvilia, Committee Member.

Growth over ontogeny can profoundly affect the form and function of biological structures. Since animal performance is tightly linked to morphological specialization, ontogenetic change in size may help structure that organism's ecological role. One measure of animal performance, bite force generation, has important ramifications in taxa which consume hard-shelled prey (durophagy). Since high bite force generation is presumably selected for in these taxa, durophagous animals provide an excellent study system for investigating ecomorphological and biomechanical consequences of growth in the feeding apparatus. Elasmobranchs (sharks, rays and skates), with relatively few cranial skeletal components make a simplified system in which to study feeding. Durophagous elasmobranchs are particularly fascinating from a material and biomechanical standpoint as their cartilaginous skeleton is typically much more pliable than the hard prey they consume. I examined through morphological dissection functional and evolutionary aspects as well as general trends in the cranial musculature of myliobatiform stingrays. Durophagous stingrays display a suite of specialized morphological characters, including hypertrophied jaw adductor muscles, characteristically deep, broad craniums, flattened, pavement-like teeth, reinforced skeletal structure, and novel tendon/sesamoid structures which redirect muscle forces during feeding. Non-durophagous stingrays are predominantly more dorso-ventrally flattened, have muscles which rely on direct, aponeurotic insertions on the skeletal structure, and display musculoskeletal specialization for jaw protrusion and independent lower jaw cartilage kinesis, relative to durophagous stingrays. In order to understand how growth affects feeding performance, an ontogenetic series of 26 cownose rays, Rhinoptera bonasus, were dissected in order to development a biomechanical model which predicts bite force generation. Muscle masses, orientation, cross-sectional areas and mechanical lever configurations were measured from the ontogenetic series of stingrays. Increases in jaw adductor muscle masses and cross-sectional areas resulted in positive allometry of bite force across ontogeny in R. bonasus. Mechanical advantage of the feeding apparatus was generally conserved throughout ontogeny, leaving increase in the size of the jaw adductors as the major component to allometric gains in bite force generation. Of primary importance to forceful biting in this taxon is the use of sesamoid structure associated with the insertion of the primary jaw adductor division. This fibrocartilaginous sesamoid serves to redirect lateral muscle forces anteriorly, transmitting force within the axial biting plane. However, measured bite forces obtained through electrostimulation of the jaw adductor divisions in live cownose rays were much higher than predicted by my biomechanical model. We believe this may be the result of differences in muscle physiology between selachian and batoid values for muscle fiber maximum tetanic tension. Caution must be prescribed when developing biomechanical models without validation through in vivo testing. / A Thesis submitted to the Department of Biological Science, College of Arts & Sciences in partial fulfillment of the requirements for the degree of Master of Science. / Fall Semester, 2012. / July 27, 2012. / batoid, bite force, durophagy, elasmobranch, feeding, functional morphology / Includes bibliographical references. / Gregory M. Erickson, Committee Member; Scott J. Steppan, Committee Member; Daniel R. Huber, Committee Member.