Parametric resonance is a particular type of resonance in which a parameter in a system changes with time. A particularly interesting case is when the parameter changes in a periodic way, which can lead to very intricate behavior. This di↵ers from periodic forcing in that solutions are not necessarily periodic. A system in which parametric resonance is realized is when a fluid bath is shaken periodically, which leads to an e↵ective time dependent gravitational force. This system will be used to study the onset of surface waves in a bath with non-uniform topography. A linear model for the surface waves is derived from the Euler equations in the limit of shallow waves, which includes the geometry of the bottom and surface tension. Experiments are performed to compare with the proposed model and good qualitative agreement is found. Another experiment which relies on a shaking fluid bath is that of bouncing fluid droplets. In the case of two droplets the shaking allows for a larger bouncing droplet to attract a smaller moving droplet in a way that creates a bound system. This bound system is studied and shows some analogous properties to quantum systems, so a quantum mechanical model for a two dimensional atom is studied, as well as a proposed model for the droplet-wave system in terms of equations of fluid mechanics.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18790号 / 理博第4048号 / 新制||理||1582(附属図書館) / 31741 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中村 卓史, 教授 鶴 剛, 教授 田中 貴浩 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

No description available.

No description available.

No description available.

Chronic ankle instability (CAI), a pathological condition characterized by repetitive bouts of the ankle giving way, commonly develops following a lateral ankle sprain injury. Individuals with CAI have been shown to exhibit deficits in postural control and alterations in movement dynamics, which have been suggested to be contributing factors to the recurrent injury paradigm. The purpose of this investigation was to conduct a comprehensive biomechanical analyses to examine the influence of CAI on postural control and movement dynamics during a single leg squat, side-cut task, and single leg landing on an inverted surface. Fifteen participants with CAI and fifteen participants without CAI completed the study following a between-subjects design, with limb serving as the repeated measure during the single leg squat. Each participant completed a single leg squat, side-cut task, and unexpected and expected single leg landings on a tilted surface. Results from the single leg squat and single leg landings on the tilted surface were analyzed using a 2 x 2 mixed-model ANOVA, while results from the side-cut task were analyzed using an independent samples t-test. Statistical significance was considered for all dependent variables when p < 0.05. Individuals with CAI demonstrated impaired postural control, as indicated by reduced time-to-boundary, during the single leg squat compared to controls. Altered ankle joint kinetics and increased sagittal plane hip joint stiffness were observed in the CAI group compared to controls. With regards to the single leg landings on the inverted surface, during the unexpected landing condition the CAI group displayed altered neuromuscular control and ankle kinematics. However, when the landing on the inverted surface as expected, the CAI group exhibited similar motor control strategies to the control group. Findings from this study indicate CAI alters postural control and movement dynamics during functional and dynamic movements, which may be used by researchers and clinicians to develop rehabilitation protocols to restore maladaptive movement patterns in individuals that develop CAI.

No description available.

Oxidative stress (OS) occurs when DNA repair mechanisms are overcome by the amount of single and double strand DNA breaks caused by an accumulation of reactive oxygen species (ROS). Genomic instability (GI) by microsatellite instability (MSI) accumulation is characterized by changes in DNA single tandem repeats (STR) as a direct result of ROS. Deregulation of DNA repair and tumor suppressor pathways have been described as causes of tumor progression and metastasis. Studies in mammals have focused on GI and the implications of increased mutation frequency due to accumulation of MSI leading to development of diseases, including infertility and cancer. Ovarian cancer is a deadly disease displaying the highest mortality rate among gynecological cancers. Hereditary ovarian cancer displays GI that can be established early in primordial germinal cells (PCGs) development and migration across the genital ridge, where PGCs are exposed to ROS damage. The hypothesis of this study was ROS-induced GI is marked by the accumulation of MSI on repetitive sequences of DNA that override DNA repair, tumor suppressor and redox homeostasis pathways. In this study, we induced ROS in human ovarian cell lines by hydrogen peroxide (H2O2) exposure, as well as evaluated mouse PGCs to determine whether MSI occurs in specific regions of human and mouse genomes. Our results show that MSI was present in specific markers after ROS-induced damage in human ovarian cells and in mouse Sod1 knockout PGCs during cell migration, both of which accumulate specific mutations caused by free radical damage. Ovarian tumor cells and mouse PGCs showed an increase of MSI in 12 human and 5 mouse repetitive markers that are located near important genes related to DNA repair, tumor suppression, cell proliferation, apoptosis and differentiation. This could be a signal that leads to tumor initiation, formation and progression in adult ovarian cells due to improper DNA repair and tumor suppression mechanisms or in disruption of PGC migration that determines germinal cell pool selection during early embryonic development due to absence of cell antioxidant mechanisms. Therefore, these specific unstable STRs are novel biomarkers that could be useful in early diagnostics, prognosis, and successful therapy of ovarian tumorigenesis.

Glioblastoma multiforme (GBM) is an extremely aggressive and almost always fatal brain tumor. GBM literature indicates defective mismatch repair (MMR) mechanisms are not involved in GBM tumorigenesis as in other tumors, and instigating mechanisms of GBM tumorigenesis remain unclear. GBM and neural progenitor (NPR) cells were exposed to three concentrations of H2O2 (0, 0.5, and 1.0 μM), cultured, and then harvested 0, 2, 4, and 6 days post-exposure; DNA from cells was amplified with microsatellite primers, investigating whether or not H2O2 exposure affected microsatellite instability (MSI) in target sequences. Three out of six markers showed significant MSI in the H2O2-exposed NPR cells. Our results suggest H2O2, which generates reactive oxygen species (ROS), correlated with MSI accumulation that occurred in NPR cells in specific DNA regions. Thus, gene expression analysis to assess normal and abnormal gene expression of GBM and NPR cellss is warranted.

BACKGROUND: Whole body vibration (WBV) platforms are currently used as adjunctive training devices for exercise programs, and have been shown to facilitate flexibility. One of the biggest contributing factors to chronic ankle instability (CAI) is the lack of dorsiflexion after lateral ankle sprains and WBV may be an effective way to increase range of motion in this population. PURPOSE: Determine if WBV done concurrently with static stretching (SS) is more effective then SS alone in improving dorsiflexion ROM in subjects with CAI. METHODS: Subjects were divided into 3 groups (control, static stretch, and static stretch and vibrate). Subjects stretched 4 days/wk for 3 wks for 4 sets of 30 seconds alternating 2 different positions to stretch both the soleus and the gastrocnemius. Imposed vibration at 34 Hz 2mm during the stretches for the stretch group. ANALYSIS: Repeated measures ANOVA was performed using SPSS (version 19), with post-hoc Tukey tests as needed (p<.05). RESULTS: In both the straight and bent leg position, a significant group x time interaction was found for dorsiflexion range of motion. Post hoc tests revealed significance in the SV group between pre-tx and post-tx 1 and pre-tx and post-tx 2. No statistical significance was found between post-tx 1 and post-tx 2 in the SV group or at any time in the N or SS group. DISCUSSION: Static Stretching with vibration increases dorsiflexion ROM in subjects with CAI better than static stretching alone.