A direct method for trajectory optimization of rigid bodies through contact

Direct methods for trajectory optimization are widely used for planning locally optimal trajectories of robotic systems. Many critical tasks, such as locomotion and manipulation, often involve impacting the ground or objects in the environment. Most state-of-the-art techniques treat the discontinuous dynamics that result from impacts as discrete modes and restrict the search for a complete path to a specified sequence through these modes. Here we present a novel method for trajectory planning of rigid-body systems that contact their environment through inelastic impacts and Coulomb friction. This method eliminates the requirement for a priori mode ordering. Motivated by the formulation of multi-contact dynamics as a Linear Complementarity Problem for forward simulation, the proposed algorithm poses the optimization problem as a Mathematical Program with Complementarity Constraints. We leverage Sequential Quadratic Programming to naturally resolve contact constraint forces while simultaneously optimizing a trajectory that satisfies the complementarity constraints. The method scales well to high-dimensional systems with large numbers of possible modes. We demonstrate the approach on four increasingly complex systems: rotating a pinned object with a finger, simple grasping and manipulation, planar walking with the Spring Flamingo robot, and high-speed bipedal running on the FastRunner platform.United States. Defense Advanced Research Projects Agency. Maximum Mobility and Manipulation Program (Grant W91CRB-11-1-0001)National Science Foundation (U.S.) (Grant IIS-0746194)National Science Foundation (U.S.) (Grant IIS-1161909)National Science Foundation (U.S.) (Grant IIS-0915148

The Role of Skills, Knowledge, and Competencies in the Consumer Adaptation Process of Immigrants to Multicultural Marketplaces: an Analysis of the Food Consumption Practices of Mexican Immigrants to the UK

This thesis analyses the role that skills, knowledge, and competencies play in the process of consumer multiculturation of immigrant consumers. Adopting Demangeot et al.’s (2015) multifaceted conceptualisation of multicultural marketplaces and focusing on the food consumption practices of Mexican immigrant consumers to the UK, the thesis seeks to extend the scope of consumer multiculturation beyond identity construction. This research adopts a qualitative methodology involving in-depth interviews and participant observation with twenty Mexican immigrants residing in the UK, supplementing this with an analysis of posts on social media sites uploaded by members of the Mexican diaspora in the UK. The study is framed by adopting practice theory as a conceptual lens, and the data is analysed using a thematic approach. A practice theory lens allows the researcher to study practices, comprising competencies, materials, and meanings (Shove et al., 2012) as opposed to individual consumers as the unit of analysis, analysing the dynamic interactions of these three elements in the context of the immigrants’ food consumption practices, thus examining culture in action. The study contributes to the theory of consumer multiculturation in a number of ways. First it adds to previous studies that focus only on consumption by identifying that immigrant consumers engage in a creative form of ‘prosumption’ (Ritzer & Jurgenson, 2010), akin to ‘craft consumption’ (Campbell, 2005) as they create and innovate while adapting to the many cultural forces comprising multicultural marketplaces. Second, it broadens the focus from the individual consumer by acknowledging that immigrant consumers create social networks, through which they engage in sharing knowledge, skills, and competencies related to food, thus increasing the complex global forces operating within multicultural marketplaces. Third, it deepens our understanding of cultural authenticity by highlighting the performative role of immigrant consumers in the food authentication process

A Direct Method for Trajectory Optimization of Rigid Bodies Through Contact ∗

Direct methods for trajectory optimization are widely used for planning locally optimal trajectories of robotic systems. Many critical tasks, such as locomotion and manipulation, often involve impacting the ground or objects in the environment. Most state-of-the-art techniques treat the discontinuous dynamics that result from impacts as discrete modes and restrict the search for a complete path to a specified sequence through these modes. Here we present a novel method for trajectory planning through contact that eliminates the requirement for an a priori mode ordering. Motivated by the formulation of multi-contact dynamics as a Linear Complementarity Problem (LCP) for forward simulation, the proposed algorithm leverages Sequential Quadratic Programming (SQP) to naturally resolve contact constraint forces while simultaneously optimizing a trajectory and satisfying nonlinear complementarity constraints. The method scales well to high dimensional systems with large numbers of possible modes. We demonstrate the approach on four increasingly complex systems: rotating a pinned object with a finger, simple grasping and manipulation, planar walking with the Spring Flamingo robot, and high speed bipedal running on the FastRunner platform.

Análisis de los efectos expansivos y redistributivos del Programa para el Bienestar de las Personas Adultas Mayores en México y sus regiones

Analizamos el Programa para el Bienestar de las Personas Adultas Mayores, cuyas reglas de operación fueron modificadas en el ejercicio fiscal 2019 (población objetivo y monto del apoyo). A través de las matrices de contabilidad social para las regiones norte, centro, centro norte y sur de México, simulamos los efectos expansivos y redistributivos de los cambios en el programa. Concluimos que la región centro es la más beneficiada, en comparación con el resto del país. No obstante, en la región sur se registra la mayor expansión en el ingreso de los más pobres

International Society for Heart and Lung Transplantation consensus statement for the standardization of bronchoalveolar lavage in lung transplantation

Bronchoalveolar lavage (BAL) is a key clinical and research tool in lung transplantation (LTx). However, BAL collection and processing are not standardized across LTx centers. This International Society for Heart and Lung Transplantation-supported consensus document on BAL standardization aims to clarify definitions and propose common approaches to improve clinical and research practice standards. The following 9 areas are covered: (1) bronchoscopy procedure and BAL collection, (2) sample handling, (3) sample processing for microbiology, (4) cytology, (5) research, (6) microbiome, (7) sample inventory/tracking, (8) donor bronchoscopy, and (9) pediatric considerations. This consensus document aims to harmonize clinical and research practices for BAL collection and processing in LTx. The overarching goal is to enhance standardization and multicenter collaboration within the international LTx community and enable improvement and development of new BAL-based diagnostics