Carnegie Mellon University

About: Carnegie Mellon University is a education organization based out in Pittsburgh, Pennsylvania, United States. It is known for research contribution in the topics: Computer science & Robot. The organization has 36317 authors who have published 104359 publications receiving 5975734 citations. The organization is also known as: CMU & Carnegie Mellon.

The focussed D* algorithm for real-time replanning

Abstract: Finding the lowest-cost path through a graph is central to many problems including route planning for a mobile robot If arc costs change during the traverse then the remainder of the path may need to be replanned. This is the case for a sensor-equipped mobile robot with imperfect information about its environment. As the robot acquires additional information via its sensors it can revise its plan to reduce the total cost of the traverse. If the prior information is grossly incomplete the robot may discover useful information in every piece of sensor data. During replanning, the robot must either wait for the new path to be computed or move in the wrong direction therefore rapid replanning is essential The D* algorithm (Dynamic A*) plans optimal traverses ID real-time by incrementally repairing paths to the robots state as new information is discovered. This paper describes an extension to D* that focusses the repairs to significantly reduce the total time required for the initial path calculation and subsequent replanning operations. This extension completes the development of the D* algorithm as a full generalizatin of A* for dynamic environments where arc costs can change during the traverse of the solution path.

Functional and anatomical cortical underconnectivity in autism: Evidence from an fMRI study of an executive function task and corpus callosum morphometry

Abstract: The brain activation of a group of high-functioning autistic participants was measured using functional magnetic resonance imaging during the performance of a Tower of London task, in comparison with a control group matched with respect to intelligent quotient, age, and gender. The 2 groups generally activated the same cortical areas to similar degrees. However, there were 3 indications of underconnectivity in the group with autism. First, the degree of synchronization (i.e., the functional connectivity or the correlation of the time series of the activation) between the frontal and parietal areas of activation was lower for the autistic than the control participants. Second, relevant parts of the corpus callosum, through which many of the bilaterally activated cortical areas communicate, were smaller in cross-sectional area in the autistic participants. Third, within the autism group but not within the control group, the size of the genu of the corpus callosum was correlated with frontal--parietal functional connectivity. These findings suggest that the neural basis of altered cognition in autism entails a lower degree of integration of information across certain cortical areas resulting from reduced intracortical connectivity. The results add support to a new theory of cortical underconnectivity in autism, which posits a deficit in integration of information at the neural and cognitive levels.

Group Versus Individual Training and Group Performance: The Mediating Role of Transactive Memory

Abstract: The task performance of laboratory work groups whose members were trained together or alone was investigated. At an initial training session, subjects were taught to assemble transistor radios. Some were trained in groups, others individually. A week later, subjects were asked to recall the assembly procedure and actually assemble a radio. Everyone performed these tasks in small work groups, each containing three persons of the same gender. Subjects in the group training condition worked in the same groups where they were trained, whereas subjects in the individual training condition worked in newly formed groups. Groups whose members were trained together recalled more about the assembly procedure and produced better-quality radios than groups whose members were trained alone. Through an analysis of videotape data, the mediating effects of various cognitive and social factors on the relationship between group training and performance were explored. The results indicated that group training improved group...

Developing Conceptual Understanding and Procedural Skill in Mathematics: An Iterative Process.

Abstract: The authors propose that conceptual and procedural knowledge develop in an iterative fashion and that improved problem representation is 1 mechanism underlying the relations between them. Two experiments were conducted with 5th- and 6th-grade students learning about decimal fractions. In Experiment 1, children's initial conceptual knowledge predicted gains in procedural knowledge, and gains in procedural knowledge predicted improvements in conceptual knowledge. Correct problem representations mediated the relation between initial conceptual knowledge and improved procedural knowledge. In Experiment 2, amount of support for correct problem representation was experimentally manipulated, and the manipulations led to gains in procedural knowledge. Thus, conceptual and procedural knowledge develop iteratively, and improved problem representation is 1 mechanism in this process.