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Access to abstract is permanently restricted to Ball State community only / Access to dissertation permanently restricted to Ball State community only / School of Physical Education, Sport, and Exercise Science

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The plant leaf is one of the most challenging natural objects to be realistically depicted by computer graphics due to its complex morphological and optical characteristics. Although many studies have been done on plant modeling, previous research on leaf modeling required for close-up realistic plant images is very rare. In this thesis, a novel method for modeling of the leaf shape based on the leaf venation is presented. As the first step of the method, the leaf domain is defined by the enclosure of the leaf boundary. Second, the leaf venation is interactively modeled as a hierarchical skeleton based on the actual leaf image. Third, the leaf domain is triangulated with the skeleton as constraints. The skeleton is articulated with nodes on the skeleton. Fourth, the skeleton is interactively transformed to a specific shape. A user can manipulate the skeleton using two methods which are complementary to each other: one controls individual joints on the skeleton while the other controls the skeleton through an intermediate spline curve. Finally, the leaf blade shape is deformed to conform to the skeleton by interpolation. An interactive modeler was developed to help a user to model a leaf shape interactively and several leaves were modeled by the interactive modeler. The ray-traced rendering images demonstrate that the proposed method is effective in the leaf shape modeling.

Researches on bone defects are focused on the use of composites due to the composite and well-organized hierarchical structure of the bone. In this study, it is aimed to develop Polycaprolactone based implants with different organic &amp / #8211 / DBM, HYA- and/or inorganic &amp / #8211 / bioglass, calcium sulfate- compositions for augmenting bone healing. Bioactivity of the discs was evaluated by scanning electron microscopy and EDS analysis after incubation in SBF for 1, 7 and 14 days. All bioglass containing groups showed apatite molecules at different incubation times. Degradation studies demonstrated that only PCL/BG/HYA discs had fast degradation upon incubations in PBS (4 and 6 weeks). Initial mechanical properties of composites were found to be directly related to the composition. However, decreases in disc mechanical properties were also obtained in the same order with the amount of water uptake at composite groups. According to biocompatibility studies investigated with cytotoxicity tests on Saos-2 cells, all groups, except the HYA involving one were found as biocompatible. After in vivo application of discs to critical size defects on rabbit humeri (for 7 weeks), their efficacy on healing was studied with computerized tomography, SEM and biomechanical tests. The results revealed that bone-implant interface formation has started for all groups with high bone densities at the interface of implant groups compared to empty defect sites of negative controls. Also the healing was suggested to be gradual from bone to implant site as microhardness values increased at regions closer to bone. However, regeneration was found to not reach to healthy bone levels.

Thesis (M.A.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Dec. 14, 2009). Includes bibliographical references (p. 134-141).

Abstract This project illustrates the use of the human's ability to balance according to his center of gravity as demonstrated in two applications. The center of gravity of a human is explained in detail in order to use it in controlling the Aldebaran NAO robot and in the robot-assisted balance training. The first application explains how a humanoid robot can mimic a human's movements via a three dimensional depth sensor where the sensor analyzes the position of a user's limbs and how the robot can lift one foot and balance on the other by redistributing the its body mass when the user lifts his foot. The results showed that this algorithm enabled NAO to successfully mimic the users' arms, and was able to balance on one foot by repositioning its center of mass. The second application investigates how individuals with stroke lean when undergoing robot-assisted balance training. In some instances, they can develop inappropriate leaning behaviors during the training. The Kinect sensor is used to assist in optimizing patients' results by integrating it with the training program. The results showed that the Kinect sensor can improve the efficiency of the process by giving users graphical information about their mass distribution and whether they are leaning correctly or not.

Proper embryonic patterning requires precise spatio-temporal regulation of retinoic acid (RA) activity. Morphogenesis can be regulated at the level of RA distribution, mainly via its synthesis and catabolism by the RALDH and CYP26 enzymes respectively, and at the level of RA-mediated transcription through activation of its cognate nuclear receptor, the retinoic acid receptors (RARs) α, β, and γ. Loss of Cyp26b1 leads to increased local levels of RA in tissues such as the limb and craniofacial structures, and results in neonatal lethality. Visible gross phenotypic defects in neonates include phocomelia (shortening of the limbs), adactyly (missing digits), micrognathia (shortened lower jaw), and open eyes at birth. In addition, these embryos exhibit cleft palate and have a paucity of vibrissal (whisker) and pelage (hair) follicles. We have previously shown that ablating the gene encoding RARγ in a Cyp26a1-null background was able to rescue the caudal abnormalities associated with improper RA exposure in these embryos by limiting aberrant RA signalling, and thus rescuing expression domains of target genes involved in caudal development. I show here that ablating Rarg in a Cyp26b1-null background is able to partially rescue the defects associated with loss of CYP26B1. These include a reduction in the severity of limb defects, rescued vibrissae, fused eyelids, and recovered aspects of axial skeletal development. This compound-null murine model illustrates that RARγ plays a specific role in transducing the RA signal within tissues that are affected by the loss of CYP26B1. Further molecular analysis of the pathways responsible for directing limb bud outgrowth and eyelid fusion provided insight into pathways regulated by RARγ in these rescued tissues. / Thesis (Ph.D, Pathology & Molecular Medicine) -- Queen's University, 2010-04-01 15:38:52.05

Access to abstract permanently restricted to Ball State community only. / School of Physical Education, Sport, and Exercise Science

Access to abstract permanently restricted to Ball State community only / Access to thesis permanently restricted to Ball State community only / School of Physical Education, Sport, and Exercise Science