An examination of the geologic features of Rock and Pipestone counties, Southwestern Minnesota, and their economic and environmental implications

The rock outcrops and glacial features exposed in Rock and Pipestone counties in southwestern Minnesota display unusual combinations of sedimentary features and occupy a strategic position for interpreting regional stratigraphic and tectonic events. Geologists have only recently begun to systematically study the area's features, and much of the past research has overlooked stratigraphic relationships and sedimentary structures, and instead emphasized the historic and economic aspects of the two counties' geologic deposits. Indeed the historic and economic aspects of the area's geologic features are extremely important, and to fully study the area and its geologic resources it is necessary to investigate the historic, economic, and environmental impact that the area's residents have had. This paper examines the stratigraphy and probable origins of the area's geologic deposits, and evaluates the area's resources with respect to their historic, economic, and environmental implications.No embarg

Contact-Aided Invariant Extended Kalman Filtering for Legged Robot State Estimation

This paper derives a contact-aided inertial navigation observer for a 3D bipedal robot using the theory of invariant observer design. Aided inertial navigation is fundamentally a nonlinear observer design problem; thus, current solutions are based on approximations of the system dynamics, such as an Extended Kalman Filter (EKF), which uses a system's Jacobian linearization along the current best estimate of its trajectory. On the basis of the theory of invariant observer design by Barrau and Bonnabel, and in particular, the Invariant EKF (InEKF), we show that the error dynamics of the point contact-inertial system follows a log-linear autonomous differential equation; hence, the observable state variables can be rendered convergent with a domain of attraction that is independent of the system's trajectory. Due to the log-linear form of the error dynamics, it is not necessary to perform a nonlinear observability analysis to show that when using an Inertial Measurement Unit (IMU) and contact sensors, the absolute position of the robot and a rotation about the gravity vector (yaw) are unobservable. We further augment the state of the developed InEKF with IMU biases, as the online estimation of these parameters has a crucial impact on system performance. We evaluate the convergence of the proposed system with the commonly used quaternion-based EKF observer using a Monte-Carlo simulation. In addition, our experimental evaluation using a Cassie-series bipedal robot shows that the contact-aided InEKF provides better performance in comparison with the quaternion-based EKF as a result of exploiting symmetries present in the system dynamics.Comment: Published in the proceedings of Robotics: Science and Systems 201

Patterns in participation: Factors influencing parent attendance at two, centre-based early childhood interventions

Interventions training parents of at-risk children have received considerable empirical support but their effectiveness is undermined by low attendance rates. This research sought to clarify why parents, even with the best of intentions, fail to follow through to full participation in workshop programs; and to provide insight into ways to improve parental engagement. We examined participation in Parents as Partners, a school-based, early childhood intervention. Demographic and ongoing educational, social, emotional and behavioural data for 136 parent-child dyads were gathered from parents, teachers and children. Mitigation of a wide range of factors previously identified as barriers to attendance was also attempted. A post-intervention survey was conducted to examine parents’ insights into their attendance patterns. Overall, 91 parents attended and 44 failed to attend any workshops. Higher parent education and SEI, and better child language skills were good predictors of attendance (87%), but poor predictors of nonattendance (42%). Additionally, parent-child dyad profiles suggested that children of nonattending parents were more likely to benefit from workshop content than attenders’ children. Survey data suggested that attenders organised their schedules to facilitate follow-through but nonattenders were unable to do so. Family characteristics and practical reasons were central, interacting factors affecting attendance. Parental self-organisation appeared to moderate follow-through and to stem from lifestyle constraints related to lower SEI and parent education. This produced high nonattendance rates in parents of children who most needed support. It is urgent to discover to what extent innovative delivery platforms currently being explored (e.g., internet/social media) can improve parental engagement

The Hyodo-Kato theorem for rational homotopy types

The Hyodo-Kato theorem relates the De Rham cohomology of a variety over a local field with semi-stable reduction to the log crystalline cohomology of the special fiber. In this paper we prove an analogue for rational homotopy types. In particular, this gives a comparison isomorphism for fundamental groups