京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第17859号 / 医博第3828号 / 新制||医||1000(附属図書館) / 30679 / 京都大学大学院医学研究科医学専攻 / (主査)教授 松田 秀一, 教授 佐藤 俊哉, 教授 戸口田 淳也 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DGAM

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Ice hockey players are at a high risk to sustain a concussion. Most of the concussion-inducing hits are to the jaw region, nevertheless, most players do not wear any protective gear shielding the jaw.  This parametric study used finite element simulations in LS-Dyna to evaluate the potential of foam materials in a jaw guard that could be attached to a helmet to reduce the concussion risk.  Here, it was investigated how nine different foam materials influence the ability of the jawguard to protect against concussion. Furthermore, aspects like foam thickness, shell thickness, and the impacting object were evaluated. In a second part, the formerly used HIII head model was exchanged with the KTH HBM, a FE model with a detailed representation of a jaw, and it was looked at how a movable jaw affects the head kinematics. Stiffer foams with a certain stress-strain behavior tend to aid best in energy absorption in the simulated crash scenarios and therefore lower the risk of sustaining a concussion. Impact angle and location influence the result significantly. Two simulated impacts show a decrease in concussion risk by up to 8.2\% and 6.9\% respectively when the jawguard was implemented, while the two other impacts resulted in an increase in concussion risk. Shell and foam thickness variation results depend mostly on the impact scenarios. However, it was found that a soft impactor helps tremendously in avoiding concussions. The hits on the KTH HBM tend to produce higher linear and angular accelerations but no significant difference is seen in angular velocity.  In conclusion, using stiff foams in ice hockey jawguards is a promising approach to attenuate impact energy caused by a collision during an ice hockey game. However, the effect of the jawguard on the concussion risk is very sensitive to the impact location and direction.

Automated grasping of objects of unknown geometry a priori has applications in many industries such as clearing a mine shaft after blasting, agricultural applications such as fruit and vegetable handling, and many roles in the service industry such as fetching items for a handicapped individual. In these roles the system environment is highly unstructured, and the robot must be able to react to different types of objects needing to be grasped. In this thesis a vision guided robotic grasp planner for unstructured environments is presented. An evaluation method for robotic grasping involving two distinct sets of objects is also presented. Both the grasp planner and evaluation metric are evaluated by experimentation using an articulated robotic arm with an eye-in-hand video camera, line laser, and pneumatic gripper. Multiple grasping experiments were performed with the objects in random poses on a modified tabletop deemed the playfield that did not allow objects to rest flat. The grasp planner focused on using a created model of the object from camera observations using silhouetting and line laser data. The object model and its computed convex hull were used to evaluate and select a single facet and point creating a grasping pair for the pneumatic gripper jaws. The grasp was attempted and then evaluated using a secondary camera and the developed evaluation method. iv Grasp success rates ranged from 80.30% (Rectangular Block on playfield 137 attempts) to 97.69% (Hexagonal Nut 173 attempts), with a mean grasp computation time for the hexagonal nut of 0.57s. / Master of Applied Science (MASc)

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ABSTRACT Background: Neck pain may influence jaw motor function. If so it would add to a growing body of evidence indicating the need for a more multidisciplinary care of affected patients. The aim of this systematic review was to review the current literature on this subject. Methods: A systematic literature search of the PubMed, Cochrane and Web of Science databases was carried out on September 20th, 2017. Included were studies with jaw motor function measurements, human participants ≥ 16 years old, with unspecified or experimental neck pain and without temporomandibular disorder (TMD) or tooth pain. Results: Of the 1701 initially identified articles, 32 were assessed in full text by two reviewers. Out of seven eligible articles, six were included after a risk of bias assessment. Two studies were contradictory on the effect of neck pain on maximal mouth opening. For maximal voluntary jaw clenching by individuals with/without neck pain, two studies showed no significant difference in force produced, and one study no significant difference in masseter muscle activity. One study showed a facilitated masseter stretch reflex in patients with neck pain. Conclusion: This systematic review shows how unexplored this field of research still is with a limited number of studies available. No firm conclusions could be drawn. Based on the included studies, neck pain seems to affect the jaw stretch reflex, but not the ability of the jaw muscles to produce force. Further research is warranted in the field of how neck pain may influence jaw motor function.

Background: Maximal voluntary occlusal bite force (MVOBF) is the maximal force applied by the jaw muscles in dental occlusion. MVOBF is one parameter for functional capacity of the jaw system.  Aim: To evaluate MVOBF in different positions in the bite and to evaluate possible intra-individual differences between sessions.  Methods: MVOBF was measured with an electronic bite force device, with transducers sensitive to force, in 20 healthy men (mean 24.5 years). Eligibility of participants was full dental occlusion, Angle Class I relation, no diagnosis according to Diagnostic criteria for temporomandibular disorders. The test included three repeated measurements on each site: first molar right, first molar left and central incisor, in random order, with test-retest study design. Unpaired T-test was used to test the MVOBF in different positions in the bite and paired T-test for possible intra-individual differences between sessions. A post hoc test for repeated measure one-way ANOVA was added.  Results: MVOBF in different positions in the bite was lower in the incisor area compared with the molar region (P<0.0001), but similar between right and left molar side (P=0.48 and P= 0.96, respectively). No intra-individual differences between sessions (molar right P= 0.40; molar left P= 0.81; incisor area P= 0.66). The intra-individual variability for repeated measurements showed variability for incisor area (P= 0.007), but not for molar right and left region (P=0.95 and P=0.49, respectively).  Conclusion: The results may provide reference values for MVOBF in young adult men, to be compared with men with pain or dysfunction in the jaw system.