As the average American age increases, there is a need to study the spine biomechanics of adults with scoliosis. Most studies examining the mechanics of scoliosis have focused on in vitro testing or computer simulations, but in vivo testing of the mechanical response of a scoliotic spine has not yet been reported. The purpose of this study was to quantitatively define the passive stiffness properties of the in vivo scoliotic spine in three principle anatomical motions and identify differences relative to healthy controls. Scoliotic (n=14) and control (n=17) participants with no history of spondylolisthesis, spinal fracture, or spinal surgery participated in three different tests (torso lateral side bending, torso axial rotation, and torso flexion/extension) that isolated mobility to the in vivo lumbar spine. Scoliotic individuals with Cobb angles ranging 15-75 degrees were accepted. Applied torque was measured using a uni-directional load cell, and inertial measurement units (IMU) recorded angular displacement of the upper torso relative to the pelvis and lower extremities. Torque-rotational displacement data were fit using a double sigmoid function, resulting in excellent overall fit (R2 > 0.901). The neutral zone (NZ) width, or the range of motion where there is minimal internal resistance, was then calculated. Stiffnesses within the NZ and outside of the NZ were also calculated. Stiffness asymmetries were also computed within each trial. These parameters were statistically compared between factor of population and within factor of direction. There was an interaction effect between populations when comparing axial twist NZ width and lateral bend NZ width. The lateral bend NZ width magnitude was significantly smaller in scoliotic patients. NZ stiffness in the all three directions was greater in the scoliotic population. There was no significant difference in asymmetrical stiffness between populations. The present study is the first investigation to quantify the in vivo neutral zone and related mechanics of the scoliotic lumbar spine. Future research is needed to determine if the measured lumbar spine mechanical characteristics can help explain progression of scoliosis and complement scoliosis classification systems. / Master of Science

Lower back injuries are an illness which plague our society. Although almost everyone will experience some form of lower back pain in his or her lifetime, it is a sickness that is poorly understood, calling for new and innovative research. Much of this back pain is attributed to mechanical factors. Hence, it is important to understand the mechanics of the spine and the mechanical effects of degenerative changes that may lead to back pain. The spine is a complex three-dimensional structure and it is therefore necessary to study its mechanics with in vitro tests that replicate physiological movements as closely as possible. Traditional spinal testing machines have been unable to simulate the kinematic behaviour of intervertebral joints as they have limited degrees of freedom and cannot produce dynamic motion. The first aim of this research was to commission a robotic testing facility to overcome the limitations of traditional testing machines. This facility incorporated a six degree-of-freedom (DOF) robot arm with a six DOF force transducer. Mechanical tests performed on this facility could simulate the dynamic three-dimensional kinematics of the lumbar spine. In addition, this research aimed to assess the existence of a region of laxity during spinal joint motion defined as the Neutral Zone, and to determine the effect of specific lesions introduced into the intervertebral disc. To investigate these aims, in vitro mechanical tests on spinal specimens were performed using the robotic testing facility. To ensure these tests produced experimental results that were indicative of the mechanics of the spine in life, the intervertebral disc height had to be representative of the disc height in life. A set of experiments was performed to determine a method for ensuring this. The post-mortem disc height change due to a period of time exposed to a moist environment, freezing, defrosting and application of a constant compressive load was documented in a group of sheep spines. Specimens that were frozen immediately upon removal from the body produced the most predictable results. These specimens required no preloading to ensure the disc height during mechanical testing was similar to that in life. In accordance with this result, specimens used in the ensuing mechanical tests were frozen immediately on removal from the body and stored frozen until required for testing. Tests performed on sheep spines with the robotic facility verified the existence of a Neutral Zone. A criterion was determined that defined the Neutral Zone as the region of spinal joint rotation where the gradient of the load/deformation curve is within +/-0.5 dNm/degree from zero. This definition was used to determine the extent of the Neutral Zone in spinal motion during different movements. A Neutral Zone of approximately four degrees was found in intact spinal motion segments during flexion/extension. Only spinal musculature can stabilise the spine in this region of rotation. The removal of the zygapophysial joints increased the Neutral Zone in flexion/extension by approximately two degrees and caused the appearance of a Neutral Zone in axial rotation of approximately one degree. This suggests that during these motions, the zygapophysial joints are the main passive stabilisers. The mechanical effects of intervertebral disc lesions were examined by experimentally introducing three types of tears (rim lesions, radial tears and concentric tears) into sheep intervertebral discs and comparing the mechanical response of the injured joint to the joint's response prior to the creation of the lesions. Radial tears and concentric tears had no effect on the maximum moments resisted by the intervertebral disc or the hysteresis of the joint's response to motion. An anterior rim lesion increased the Neutral Zone by approximately 1.5 degrees and reduced the maximum moment resisted by the intervertebral disc by approximately 20% during extension in L1/L2 specimens. Rim lesions were also found to reduce the maximum moment resisted by the intervertebral disc in lateral bending and axial rotation for all levels by approximately 15% and 25% respectively. Rim lesions did not affect the hysteresis of intervertebral disc motion. In summary, this research commissioned a robotic testing facility capable of simulating the dynamic, three-dimensional kinematics of the lumbar spine and provided a unique insight into the three-dimensional mechanics of intervertebral joints. Testing was performed on sheep joints, however the outcomes provide an insight into the mechanical response of the human spine. The Neutral Zone was shown to exist but only in flexion/extension. This implies that damage to the spinal muscles may produce an unstable structure during flexion/extension within this Neutral Zone. Rim lesions reduce the ability of the intervertebral disc to resist all modes of motion. This suggests that the presence of rim lesions will produce overloading of other spinal elements and instigate progressive degenerative changes.

Crosslinking soft tissue has become more common in tissue engineering applications, and recent studies have demonstrated that soft tissue mechanical behavior can be directly altered through crosslinking, but increased understanding of how crosslinking affects intervertebral disc mechanical behavior is needed. In vitro testing of bovine disc and motion segments was used to characterize several important aspects of disc behavior in response to crosslinking after both soaking and injection treatment. The first study was a comparison of different crosslinkers to determine the effect on tensile properties of disc tissue. Circumferential specimens were taken from bovine annulus and then soak treated with an optimized crosslinking formulation or sham solution. A non-contacting laser micrometer was used to measure cross sectional area, after which tension testing until failure was performed to determine yield strain, yield stress, ultimate stress, peak modulus, and resilience. The crosslinkers were observed to produce different changes in the properties, with the measured properties generally increasing. The second study used bilateral annular injections to simulate a clinically relevant delivery method. The dose response of the motion segment’s neutral zone stability metrics against injection concentration was mapped. Concentrations of 20 mM and less had no significant effects on the stability metrics. 40mM demonstrated a change in neutral zone stiffness, while at least 80mM was required to significantly affect neutral zone length. Thus, meaningful changes in joint neutral zone stability were demonstrated using clinically relevant injection and chemical formulations. The third study used combinations of biochemical and accelerated mechanical cyclic loading to degrade gelatin and annulus fibrosus specimens with and without genipin treatment. Genipin crosslinking attenuated changes during cyclic loading to specimen geometry and compliance relative to control samples. Full recovery of genipin treated samples appeared to be hampered, at least partially from continued crosslinking during the accelerated testing. The fourth study tested the effect of genipin crosslinking to resist interlamellar shearing of the annulus lamella. Using a recently reported test method that shears adjacent lamella, crosslinked specimens were noted to have significantly higher yield force, peak force, and resilience compared to sham treated controls, supporting the hypothesis that crosslinking would increase the load bearing ability of the interface.

Philosophiae Doctor - PhD / Rehabilitation of edentulous jaws without the option of osseointegrating implants will remain the only treatment option within reach of many older patients for the foreseeable future. Many routine prosthodontic procedures are based on dogmas, because no high-level scientific evidence exists to either accept or reject them, among these is the “neutral zone” (NZ) concept. In spite of paucity of evidence using approved patient-based outcome instruments, it is generally agreed that the NZ should be respected when constructing complete dentures. The purpose of this research project was to determine how shapes of conventional and NZ mandibular dentures differ, and if the two different types of dentures impact differently on oral health–related quality of life by using an accepted oral health-related quality of life instrument as a patient-based outcome. Thirty nine edentulous patients were selected for this prospective, randomised, cross-over, single-blinded clinical trial. Two sets of complete dentures were made for each patient. One denture set was made following conventional biometric guidelines for determining the position of the mandibular posterior denture teeth in relation to the ridge; another set was made following a functional impression of the potential denture space. Each set of dentures was worn for at least two months. A similar number of types of dentures were delivered first. Widths of residual ridges and mandibular denture arches were measured using digital measuring software. Position of denture teeth was related to the ridge. Denture dimensions were compared by means of analysis of variance using the mixed procedure. Using formula of parabola, arch-widths were compared using paired t-tests. Pre- and post-treatment patient feedback was obtained by means of the 20-item Oral Health Impact Profile (OHIP-20) and a preference score. Treatment effect size (ES) was established based on the OHIP-20 scores. Relevant associations among denture dimensions, OHIP-20 scores, preference, age, gender, marital status, education, income, period of edentulousness, and quality of denture-bearing tissue were done using the generalised linear model and correlation analysis. For all statistical analysis, level of significance was determined at p<0.05. The mean age of the sample was 62.3 years. Twenty four patients were female. Mean period of edentulousness was 31 years and mean number of denture sets worn prior to the trial was 2.5. Except for the canine region, NZ dentures were statistically wider than anatomic dentures. The difference in mean widths between the two types of dentures was larger for female patients. Older patients had smaller differences in denture dimensions. More unfavourable denture-bearing tissue was associated with a larger difference in the two types of dentures. Both types of mandibular dentures significantly improved the OHRQoL of patients. Both types of dentures had a high treatment ES. The OHIP-20 instrument could not distinguish a statistical difference in impact on OHRQoL between the two treatment options. There was a minute difference in treatment ES between the two types of treatment. The only domain representing a small clinical benefit between NZ and anatomic dentures was “physical pain”, with the NZ dentures scoring better. There was no correlation between pre- and post-treatment scores for both types of dentures. No significant associations were found between post-treatment OHIP- 20 scores on the one hand and tissue scores, gender, age, education, marital status, period of edentulousness and denture dimension differences on the other hand. Based on OHIP-20 scores, there was a significant association between denture preference and NZ dentures, but not for the other preferences. No significant associations were found between denture preferences on the one hand and tissue scores, gender, age, period of edentulousness and denture dimension differences on the other hand. Even though no significant relationship was found between preference and gender, the majority of female patients preferred the NZ denture and the majority of male patients did not express a preference. Providing new complete dentures improved OHRQoL of edentulous patients. The majority of female patients preferred the NZ compared over the ANA denture. The NZ technique appeared to have a higher positive impact on OHRQoL of female patients compared to male patients.

Philosophiae Doctor - PhD / Rehabilitation of edentulous jaws without the option of osseointegrating implants will remain the only treatment option within reach of many older patients for the foreseeable future. Many routine prosthodontic procedures are based on dogmas, because no high-level scientific evidence exists to either accept or reject them, among these is the “neutral zone” (NZ) concept. In spite of paucity of evidence using approved patient-based outcome instruments, it is generally agreed that the NZ should be respected when constructing complete dentures. The purpose of this research project was to determine how shapes of conventional and NZ mandibular dentures differ, and if the two different types of dentures impact differently on oral health–related quality of life by using an accepted oral health-related quality of life instrument as a patient-based outcome. Thirty nine edentulous patients were selected for his prospective, randomised, cross-over, single-blinded clinical trial. Two sets of complete dentures were made for each patient. One denture set was made following conventional biometric guidelines for determining the position of the mandibular posterior denture teeth in relation to the ridge; another set was made following a functional impression of the potential denture space. Each set of dentures was worn for at least two months. A similar number of types of dentures were delivered first. Widths of residual ridges and mandibular denture arches were measured using digital measuring software. Position of denture teeth was related to the ridge. Denture dimensions were compared by means of analysis of variance using the mixed procedure. Using formula of parabola, arch-widths were compared using paired t-tests. Pre- and post-treatment patient feedback was obtained by means of the 20-item Oral Health Impact Profile (OHIP-20) and a preference score. Treatment effect size (ES) was established based on the OHIP-20 scores. Relevant associations among denture dimensions, OHIP-20 scores, preference, age, gender, marital status, education, income, period of edentulousness, and quality of denture-bearing tissue were done using the generalised linear model and correlation analysis. For all statistical analysis, level of significance was determined at p<0.05. The mean age of the sample was 62.3 years. Twenty four patients were female. Mean period of edentulousness was 31 years and mean number of denture sets worn prior to the trial was 2.5. Except for the canine region, NZ dentures were statistically wider than anatomic dentures. The difference in mean widths between the two types of dentures was larger for female patients. Older patients had smaller differences in denture dimensions. More unfavourable denture-bearing tissue was associated with a larger difference in the two types of dentures. Both types of mandibular dentures significantly improved the OHRQoL of patients. Both types of dentures had a high treatment ES. The OHIP-20 instrument could not distinguish a statistical difference in impact on OHRQoL between the two treatment options. There was a minute difference in treatment ES between the two types of treatment. The only domain representing a small clinical benefit between NZ and anatomic dentures was “physical pain”, with the NZ dentures scoring better. There was no correlation between pre- and post-treatment scores for both types of dentures. No significant associations were found between post-treatment OHIP- 20 scores on the one hand and tissue scores, gender, age, education, marital status, period of edentulousness and denture dimension differences on the other hand. Based on OHIP-20 scores, there was a significant association between denture preference and NZ dentures, but not for the other preferences. No significant associations were found between denture preferences on the one hand and tissue scores, gender, age, period of edentulousness and denture dimension differences on the other hand. Even though no significant relationship was found between preference and gender, the majority of female patients preferred the NZ denture and the majority of male patients did not express a preference.Providing new complete dentures improved OHRQoL of edentulous patients. The majority of female patients preferred the NZ compared over the ANA denture. The NZ technique appeared to have a higher positive impact on OHRQoL of female patients compared to male patients.

Historically, disenfranchised students in the American education system have been promised opportunity through successful participation in the school system. These promises are voiced in legislation like the Elementary and Secondary Education Act of 1965 and by executive actions like President Obama’s Race to the Top Initiative. Evidenced by the continuing education gap, the promises of success through education continue to evade many American children across the nation, especially students who are most in need of the support promised in these quixotic visions of opportunity. This is a qualitative interview study that aimed to gather the voices of educators involved in the implementation of the English Language Arts Common Core State Standards (ELA CCSS) to investigate the potential benefit of an information loop during the time period Bridges (2009) labeled the Neutral Zone, a period when change agents can reflect on and possibly enhance the implementation of an initiative. The study aimed to answer the following research question: What are the experiences of teachers, school principals, and district-level administrators during the transition to the ELA CCSS in three public school districts in the greater Los Angeles area? The narratives constructed throughout the interview process with the study’s participants point to the value of establishing an information loop during the Neutral Zone as an untapped vein of knowledge in the change process. This information can potentially be used to take inventory of the trajectory an implementation process has taken.

Biomechanical testing of cadaveric spinal segments forms the basis for our current understanding of healthy, pathological, and surgically treated spinal function. Over the past 40 years there has been a substantial amount of data published based on a spinal biomechanical testing regimen known as the flexibility method. This data has provided valuable clinical insights that have shaped our understanding of low back pain and its treatments. Virtually all previous lumbar spinal flexibility testing has been performed at room temperature, under very low motion rates, without the presence of a compressive follower-load to simulate upper body weight and the action of the musculature. These limitations of previous work hamper the applicability of published spinal biomechanics data, especially as researchers investigate novel ways of treating low back pain that are intended to restore the spine to a healthy biomechanical state. Thus, the purpose of this thesis work was to accurately characterize the rate-dependent flexibility of the lumbar spine at body temperature while in the presence of a compressive follower-load. A custom spine simulator with an integrated environmental chamber was developed and built as part of this thesis work. Cadaveric spinal motion segments were tested at 12 different rates of loading spanning the range of voluntary motion rates. The testing methodology allowed for comparison of spinal flexibility at room and body temperatures in the three primary modes of spinal motion, both with and without a compressive follower-load. Additionally, the work developed a stochastic model for rate-dependent spinal flexibility that allows for accurate prediction of spinal flexibility at any rate within the range of voluntary motion, based on a single flexibility test. In conclusion, the biomechanical response was significantly altered due to testing temperature, loading-rate, and application of a compressive follower-load. The author emphasizes the necessity to simulate the physiological environment during ex vivo biomechanical analysis of the lumbar spine in order to obtain a physiological response. Simplified testing procedures may be implemented only after the particular effect is known.

Approved for public release, distribution is unlimited / This thesis attempts to create a desire for change in DoD's current approach to Network Application Management (NAM). The evolution of NAM into Integrated Network Application Management (INAM) is a crucial component of Network Centric Warfare and achieving Information Superiority and Interoperability. INAM is outlined as three functional requirements, which are Network Awareness, Mission Prioritization linkage to Network Resources, and the Balancing of Service Management. Scenarios play a key role in illustrating the new threats that DoD faces today. These scenarios also identify limitations and challenges to NAM as it exists today. These challenges require significant improvements in flexibility and responsiveness, while providing for wide integration. Trends supporting change are identified in this thesis. Two of the more important trends are the rise of Architectural and Object Oriented Development. Examples such as Training and Testing Enabled Architecture (TENA), Surveillance and Target Acquisition Network (STAN), and Virtual Proving Ground (VPG) are clear examples of these trends. The merging of the Computer Industry's efforts to expand the reach of Operating Systems with the traditional efforts from Network Management is also a trend that is examined. Organizations like Distributed Management Task Force (DMTF) are important to such examinations. Successful change can not be achieved without planning for the transition. This thesis also presents some active transition efforts addressing Network Centric Warfare. TENA, VPG and Naval Postgraduate School's Information Technology Management Master's Program provide three examples of addressing transition in DoD. / Civilian, United States Army Yuma Proving Ground

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