Parallelizing RRT on large-scale distributed-memory architectures

This paper addresses the problem of parallelizing the Rapidly-exploring Random Tree (RRT) algorithm on large-scale distributed-memory architectures, using the Message Passing Interface. We compare three parallel versions of RRT based on classical parallelization schemes. We evaluate them on different motion planning problems and analyze the various factors influencing their performance

Parallelizing RRT on distributed-memory architectures

This paper addresses the problem of improving the performance of the Rapidly-exploring Random Tree (RRT) algorithm by parallelizing it. For scalability reasons we do so on a distributed-memory architecture, using the message-passing paradigm. We present three parallel versions of RRT along with the technicalities involved in their implementation. We also evaluate the algorithms and study how they behave on different motion planning problems

Enhancing the Transition-based RRT to deal with complex cost spaces

The Transition-based RRT (T-RRT) algorithm enables to solve motion planning problems involving configuration spaces over which cost functions are defined, or cost spaces for short. T-RRT has been successfully applied to diverse problems in robotics and structural biology. In this paper, we aim at enhancing T-RRT to solve ever more difficult problems involving larger and more complex cost spaces. We compare several variants of T-RRT by evaluating them on various motion planning problems involving different types of cost functions and different levels of geometrical complexity. First, we explain why applying as such classical extensions of RRT to T-RRT is not helpful, both in a mono-directional and in a bidirectional context. Then, we propose an efficient Bidirectional T-RRT, based on a bidirectional scheme tailored to cost spaces. Finally, we illustrate the new possibilities offered by the Bidirectional T-RRT on an industrial inspection problem

On the Design of Education Conditional Cash Transfer Programs and non Education Outcomes: The Case of Teenage Pregnancy

We investigate the effect of education Conditional Cash Transfer programs (CCTs) on teenage pregnancy. Our main concern is with how the size and sign of the effect may depend on the design of the program. Using a simple model we show that an education CCT that conditions renewal on school performance reduces teenage pregnancy; the program can increase teenage pregnancy if it does not condition on school performance. Then, using an original data base, we estimate the causal impact on teenage pregnancy of two education CCTs implemented in Bogotá (Subsidio Educativo, SE, and Familias en Acción, FA); both programs differ particularly on whether school success is a condition for renewal or not. We show that SE has negative average effect on teenage pregnancy while FA has a null average effect. We also find that SE has either null or no effect for adolescents in all age and grade groups while FA has positive, null or negative effects for adolescents in different age and grade groups. Since SE conditions renewal on school success and FA does not, we can argue that the empirical results are consistent with the predictions of our model and that conditioning renewal of the subsidy on school success crucially determines the effect of the subsidy on teenage pregnancy.teenage risk taking behavior, teenage pregnancy, education, conditional cash transfers, incentives

On the design of education conditional cash transfer programs and non education outcomes: the case of teenage pregnancy

ABSTRACTWe investigate the effect of education Conditional Cash Transfer programs (CCTs) on teenage pregnancy. Our main concern is with how the size and sign of the effect may depend on the design of the program. Using a simple model we show that an education CCT that conditions renewal on school performance reduces teenage pregnancy; the program can increase teenage pregnancy if it does not condition on school performance. Then, using an original data base, we estimate the causal impact on teenage pregnancy of two education CCTs implemented in Bogotá (Subsidio Educativo, SE, and Familias en Acción, FA); both programs differ particularly on whether school success is acondition for renewal or not. We show that SE has negative average effect on teenage pregnancy while FA has a null average effect. We also Find that SE has either null or no effect for adolescents in all age and grade groups while FA has positive, null or negative effects for adolescents in different age and grade groups. Since SE conditions renewal on school success and FA does not, we can argue that the empirical results are consistent with the predictions of our model and that conditioning renewal of the subsidy on school success crucially determines the eect of the subsidy on teenage pregnancy.Teenage risk taking behavior, Teenage pregnancy, Education, Conditional Cash Transfers, Incentives.

Improving I/O performance through an in-kernel disk simulator

This paper presents two mechanisms that can significantly improve the I/O performance of both hard and solid-state drives for read operations: KDSim and REDCAP. KDSim is an in-kernel disk simulator that provides a framework for simultaneously simulating the performance obtained by different I/O system mechanisms and algorithms, and for dynamically turning them on and off, or selecting between different options or policies, to improve the overall system performance. REDCAP is a RAM-based disk cache that effectively enlarges the built-in cache present in disk drives. By using KDSim, this cache is dynamically activated/deactivated according to the throughput achieved. Results show that, by using KDSim and REDCAP together, a system can improve its I/O performance up to 88% for workloads with some spatial locality on both hard and solid-state drives, while it achieves the same performance as a ‘regular system’ for workloads with random or sequential access patterns.Peer ReviewedPostprint (author's final draft

Several stories about tripeptides: basic components for modeling flexible protein structures

From a mechanical point of view, fragments of three consecutive amino acid residues (called tripeptides hereafter) are very interesting elements of polypeptide chains. Indeed, if we consider the bond torsion angles as the main degrees of freedom, the 6 angles in a tripeptide (3 pairs of phi-psi angles, neglecting the variation of omega angles) are the minimal number allowing full relative mobility of the two ends of the chain. Besides, using techniques originating from robotics, the angle values corresponding to a given pose of the two ends the can be obtained very efficiently. This property has been exploited over decades within conformational sampling methods applied to cyclic peptides or protein loops. It can also be used to enhance conformational sampling of globular proteins using Monte Carlo methods, or to conceive sophisticated algorithms for modeling large-amplitude conformational transitions. In the first part of my presentation, I will briefly talk about all these applications. Tripeptides are also interesting elements from a structural point of view. They are minimalistic fragments capturing local, sequence-dependent structural preferences of proteins. To encode and to analyze these structural properties, we have constructed an exhaustive database to tripeptide conformations extracted from experimentally-determined high-resolution protein structures. In the second part of the talk, I will show how this database can be used to construct realistic models of intrinsically disordered proteins (IDPs) and to predict the propensity of some regions to form secondary structure elements

Movilización de la competencia matemática representar a partir de una propuesta didáctica mediante el estudio de la función lineal

En este documento se presenta una propuesta inclusiva de la enseñanza de la ubicación y localización espacial para estudiantes de grado 3° incluyendo estudiantes con discapacidad visual, en la cual se desea realizar a la población inicialmente una apropiación conceptual por medio de procesos de formación e instrucción y un desarrollo del trabajo propuesto. Esta propuesta inclusiva en torno al pensamiento espacial, específicamente la localización (sistemas de referencia), permitirá que los estudiantes reconozcan y puedan describir las características de los sistemas de referencia, para ubicarse y orientarse en el espacio

Los reflejos de una idea: sobre los 860/880 Lake Shore Drive Esplanade apartments de Mies Van Der Rohe

Los reflejos de una idea: sobre los 860/880 Lake Shore Drive Esplanade apartments de Mies Van Der Roh