The Effects of Locomotion-Induced Shock Loading on Tibiofemoral Bone Stress Response

Purpose/Hypothesis: Knee osteoarthritis (Coats, Zioupos, & Aspden) is a degenerative joint disease that negatively impacts the quality of life. About 9.3 million people in the U.S. population are affected. It has been suggested via magnetic resonance imaging (MRI) studies that bone marrow edema (i.e., indicative of bone stress response) and joint structure changes may be the main contributing factors of pain in OA. Frontal plane lower extremity (LE) alignment has been a topic of much interest regarding development of OA in the knee joint. It is hypothesized that varus alignment increases forces through the medial compartment of the knee, thereby leading to bone stress response and initiation of OA. The purpose was to investigate the effects of locomotion-induced shock loading and LE alignment on tibiofemoral bone stress response in older adults without knee OA. Number of Subjects: Five male and five female subjects with no medical diagnosis of knee OA (57.9 ± 3.9 years; 84.2 ± 12.7 kg; 1.7 ± 0.1 m) participated. Materials/Methods: Each subject underwent a clinical biomechanical testing session and an MRI assessment session. During the clinical biomechanical testing, static LE alignment was obtained by measuring the angle between the long axes of femur and tibia. Dynamic LE alignment, in particular the peak frontal plane LE angle during loading response of fast walking, was obtained using a 3-dimensional motion capturing system. During the MRI assessment session, a chemical-shift-encoded water-fat MRI protocol was applied to the dominant knee. MRI data was obtained before fast walking and immediately following a 30-minute fast walking session. Bone stress response was determined by quantifying the bone water content within the weight-bearing regions of iii the medial and lateral compartments. Paired t-tests were used to compare bone water content before and after fast walking. Pearson correlation coefficient analyses were used to determine the associations between LE alignment and changes in water content after fast walking. Results: The paired t-tests revealed no change in water content after fast walking within medial femur (p = 0.671), lateral femur (p =0.174), medial tibia (p = 0.461), and lateral tibia (p = 0.190). Pearson correlation coefficient analyses revealed a significant moderate correlation between increased bone water content of the medial femur and increased static varus alignment (R = 0.688, p =0.027). Additionally, a trend with moderate correlation was observed between increased bone water content of the medial tibia and increased static varus alignment (R = 0.437, p = 0.206). No association was found between changes in bone water content and dynamic alignment (p \u3c 0.05). Conclusions: This is the first study assessing the acute effects of locomotion on bone stress response in older adults without knee OA. Although there was no significant change in bone water content post locomotion, a greater varus alignment was associated with increased water content in the medial compartment. Clinical Relevance: Our findings provide further understanding of the contribution of LE alignment and development of OA. This research can impact the early detection, prevention, and interventions for individuals at risk for joint deformity and knee OA

Rescheduling with iterative repair

This paper presents a new approach to rescheduling called constraint-based iterative repair. This approach gives our system the ability to satisfy domain constraints, address optimization concerns, minimize perturbation to the original schedule, produce modified schedules, quickly, and exhibits 'anytime' behavior. The system begins with an initial, flawed schedule and then iteratively repairs constraint violations until a conflict-free schedule is produced. In an empirical demonstration, we vary the importance of minimizing perturbation and report how fast the system is able to resolve conflicts in a given time bound. We also show the anytime characteristics of the system. These experiments were performed within the domain of Space Shuttle ground processing

Rescheduling with iterative repair

This paper presents a new approach to rescheduling called constraint-based iterative repair. This approach gives our system the ability to satisfy domain constraints, address optimization concerns, minimize perturbation to the original schedule, and produce modified schedules quickly. The system begins with an initial, flawed schedule and then iteratively repairs constraint violations until a conflict-free schedule is produced. In an empirical demonstration, we vary the importance of minimizing perturbation and report how fast the system is able to resolve conflicts in a given time bound. These experiments were performed within the domain of Space Shuttle ground processing

Construction of equilibrium networks with an energy function

We construct equilibrium networks by introducing an energy function depending on the degree of each node as well as the product of neighboring degrees. With this topological energy function, networks constitute a canonical ensemble, which follows the Boltzmann distribution for given temperature. It is observed that the system undergoes a topological phase transition from a random network to a star or a fully-connected network as the temperature is lowered. Both mean-field analysis and numerical simulations reveal strong first-order phase transitions at temperatures which decrease logarithmically with the system size. Quantitative discrepancies of the simulation results from the mean-field prediction are discussed in view of the strong first-order nature.Comment: To appear in J. Phys.

Scheduling and rescheduling with iterative repair

This paper describes the GERRY scheduling and rescheduling system being applied to coordinate Space Shuttle Ground Processing. The system uses constraint-based iterative repair, a technique that starts with a complete but possibly flawed schedule and iteratively improves it by using constraint knowledge within repair heuristics. In this paper we explore the tradeoff between the informedness and the computational cost of several repair heuristics. We show empirically that some knowledge can greatly improve the convergence speed of a repair-based system, but that too much knowledge, such as the knowledge embodied within the MIN-CONFLICTS lookahead heuristic, can overwhelm a system and result in degraded performance

Goal-scenario-oriented requirements engineering for functional decomposition with bidirectional transformation to controlled natural language: Case study "body control module"

Requirements for embedded systems are mainly documented using natural language. This is due to the fact that natural language does not require special nomenclature knowledge and is accepted as the basis for contractual agreements. However, purely natural-language-based requirements engineering (RE) is often error-prone, potentially ambiguous, and does not foster traceability and hence requires tedious manual reviews and analyses. Model-based requirements engineering is often considered a possible solution as models enhance traceability, aid in stakeholder communication, and foster automatic model analysis and model checking. However, model-based requirements engineering is only slowly adopted in the industry, partly because no clear guidelines to their application exist, particularly in legally binding documents. In order to combine the advantages of model-based requirements engineering with the convenience of natural-language-based requirements engineering, we developed a combined RE approach that relies on both a controlled natural language (i.e., a natural language that is restricted in its expressiveness) as well as requirements models and defines a structured interface between both specification paradigms. The purpose of this document is to report on the application of the combined approach in an industrial case study from the automotive industry: a body control module. A body control module is an electronic control unit (ECU) that centralizes the control of body and comfort functions provided by multiple other ECUs distributed in a vehicle. The case study illustrates how controlled natural language as well as requirements models can be used in order to specify solution-neutral goal and scenario models as well as functional requirements of a body control module across multiple layers of abstraction

Turismo em Cabo Verde:um estudo exploratório

Esta dissertação é um trabalho exploratório sobre o turismo em Cabo Verde. Partindo de um esquema teórico herdeiro fundamentalmente da Sociologia e Antropologia do turismo, começaremos por discutir alguns dos seus temas centrais para o nosso objecto de estudo. O turismo em Cabo Verde é assumido como o eixo central do desenvolvimento do país e a indústria turística cabo-verdiana encontra-se em franca expansão. Através de uma caracterização do fenómeno turístico em Cabo Verde, desde o seu florescimento até aos dias de hoje, pretendemos dar conta da evolução do sector e das recentes reconfigurações no panorama turístico cabo-verdiano que se espelham nos discursos narrativos e visuais presentes na promoção turística deste destino. Com base numa análise do discurso promocional, procuramos desvendar a forma como este arquipélago é descrito enquanto destino turístico, revelando a diversidade de elementos presentes na imagem turística contemporânea de Cabo Verde.This dissertation is an exploratory work about tourism in Cape Verde. By framing a theoretical scheme based on the Sociology and the Anthropology of tourism, we discuss some of its themes that are critical to our object of study. Tourism in Cape Verde is taken as the central axis of the country‟s development, and the Cape Verdean touristic industry is in large expansion. Through a characterization of the touristic phenomenon in Cape Verde, since its beginnings until today, we attempt to report its evolution and the recent reconfigurations in the Cape Verdean touristic scenery which are reflected in narrative and visual discourses that promote this destination. By means of an analysis of the promotional discourse, we seek to unravel how this archipelago is described as a touristic destination, revealing the diversity of elements that build the contemporary touristic image of Cape Verde