Footstep and Motion Planning in Semi-unstructured Environments Using Randomized Possibility Graphs

Traversing environments with arbitrary obstacles poses significant challenges for bipedal robots. In some cases, whole body motions may be necessary to maneuver around an obstacle, but most existing footstep planners can only select from a discrete set of predetermined footstep actions; they are unable to utilize the continuum of whole body motion that is truly available to the robot platform. Existing motion planners that can utilize whole body motion tend to struggle with the complexity of large-scale problems. We introduce a planning method, called the "Randomized Possibility Graph", which uses high-level approximations of constraint manifolds to rapidly explore the "possibility" of actions, thereby allowing lower-level motion planners to be utilized more efficiently. We demonstrate simulations of the method working in a variety of semi-unstructured environments. In this context, "semi-unstructured" means the walkable terrain is flat and even, but there are arbitrary 3D obstacles throughout the environment which may need to be stepped over or maneuvered around using whole body motions.Comment: Accepted by IEEE International Conference on Robotics and Automation 201

Dental Maturation in Children Treated for Acute Lymphocytic Leukemia

Acute lymphocytic leukemia (ALL) is a life-threatening disease primarily affecting children. Treatment currently consists of chemotherapy sometimes in combination with head irradiation. The literature documents the damage of treatment to the teeth (e.g., congenital absence, microdontia, abnormal crown- root ratios). The present study assessed the effects of treatment for ALL on the tempos of dental maturation (i.e., dental age) in a mixed longitudinal sample of 72 children treated for ALL at St Jude\u27s Children\u27s\u27 Research Hospital, Memphis, Tennessee. Panoramic radiographs had been taken as indicated to assess and maintain dental health in this retrospective study. Dental age was quantified both on a tooth-specific basis and averaged across all scorable teeth using published standards for American whites. The tempo of toothformation was gauged as dental age (DA) minus chronological age (CA). Children were developmentally normal (DA=CA) at the onset of ALL, and there was no sex difference in response to treatment. No statistically significant developmental delay was found during the first two years from the onset of treatment, perhaps because tooth mineralization progresses slowly enough that effects were obscured. From two years onward, DA was significantly depressed. The effect of chemotherapy alone only had a slight negative effect on DA. The addition of irradiation to chemotherapy had a significant additive effect on DA, as well as increasing the incidence of developmental variants such as stunted roots (i.e., roots with apical closure prior to achieving normal length). Importantly, there was no evidence of a compensatory increase in the tempo of growth following treatment. The chemotherapeutic treatment for ALL is a serious stressor to the body\u27s tempo of growth, and the addition of irradiation therapy significantly adds to the negative effect on the tempo of dental maturation. Significant developmental delay was not seen until two years after the start of treatment, either because the dentition is buffered from the stresses of treatment or because the morphological changes are slow to occur. The end result of treatment for ALL is delayed tooth maturation in addition to the previously documented risks of developmental dental anomalies

Faithful Estimation of Dynamics Parameters from CPMG Relaxation Dispersion Measurements

This work examines the robustness of fitting of parameters describing conformational exchange (kex, pa/b, and Δω) processes from CPMG relaxation dispersion data. We have analyzed the equations describing conformational exchange processes for the intrinsic inter-dependence of their parameters that leads to the existence of multiple equivalent solutions, which equally satisfy the experimental data. We have used Monte-Carlo simulations and fitting to the synthetic data sets as well as the direct 3-D mapping of the parameter space of kex, pa/b, and Δω to quantitatively assess the degree of the parameter inter-dependence. The demonstrated high correlation between parameters can preclude accurate dynamics parameter estimation from NMR spin-relaxation data obtained at a single static magnetic field. The strong parameter inter-dependence can readily be overcome through acquisition of spin-relaxation data at more than one static magnetic field thereby allowing accurate assessment of conformational exchange properties

Anatomy and Physiology of Knee Stability

Knee instability has been the focus of large number of studies over the last decade; however, a high incidence rate of injury still exists. The aim of this short report is to examine knee joint anatomy and physiology with respect to knee stability. Knee joint stability requires the integration of a complex set of anatomical structures and physiological mechanism. Compromising any of these structures leads to destabilisation and increased risk of injuries. This review highlights the structure and soft tissue of the knee that contribute to its stability and function. This introduction is part of the Journal of Functional Morphology and Kinesiology’s Special Issue “The Knee: Structure, Function and Rehabilitation”

Forecasting tropical cyclone surge

Hydrodynamic