An autonomous folding unit mediates the assembly of two-stranded coiled coils

Subunit oligomerization of many proteins is mediated by coiled-coil domains. Although the basic features contributing to the thermodynamic stability of coiled coils are well understood, the mechanistic details of their assembly have not yet been dissected. Here we report a 13-residue sequence pattern that occurs with limited sequence variations in many two-stranded coiled coils and that is absolutely required for the assembly of the Dictyostelium discoideum actin-bundling protein cortexillin I and the yeast transcriptional activator GCN4. The functional relationship between coiled-coil “trigger” sequences was manifested by replacing the intrinsic trigger motif of GCN4 with the related sequence from cortexillin I. We demonstrate that these trigger sequences represent autonomous helical folding units that, in contrast to arbitrarily chosen heptad repeats, can mediate coiled-coil formation. Aside from being of general interest for protein folding, trigger motifs should be of particular importance in the protein de novo design.

Cell autonomous regulation of multiple Dishevelled-dependent pathways by mammalian Nkd

Genetic studies have identified Drosophila Naked Cuticle (Nkd) as an antagonist of the canonical Wnt/β-catenin signaling pathway, but its mechanism of action remains obscure [Zeng, W., Wharton, K. A., Jr., Mack, J. A., Wang, K., Gadbaw, M., et al. (2000) Nature (London) 403, 789–795]. Here we have cloned a cDNA encoding a mammalian homolog of Drosophila Nkd, mNkd, and demonstrated that mNkd interacts directly with Dishevelled. Dishevelled is an intracellular mediator of both the canonical Wnt pathway and planar cell polarity (PCP) pathway. Activation of the c-Jun-N-terminal kinase has been implicated in the PCP pathway. We showed that mNkd acts in a cell-autonomous manner not only to inhibit the canonical Wnt pathway but also to stimulate c-Jun-N-terminal kinase activity. Expression of mNkd disrupted convergent extension in Xenopus, consistent with a role for mNkd in the PCP pathway. These data suggest that mNkd may act as a switch to direct Dishevelled activity toward the PCP pathway, and away from the canonical Wnt pathway.

Novel Gq alpha isoform is a candidate transducer of rhodopsin signaling in a Drosophila testes-autonomous pacemaker.

DGq is the alpha subunit of the heterotrimeric GTPase (G alpha), which couples rhodopsin to phospholipase C in Drosophila vision. We have uncovered three duplicated exons in dgq by scanning the GenBank data base for unrecognized coding sequences. These alternative exons encode sites involved in GTPase activity and G beta-binding, NorpA (phospholipase C)-binding, and rhodopsin-binding. We examined the in vivo splicing of dgq in adult flies and find that, in all but the male gonads, only two isoforms are expressed. One, dgqA, is the original visual isoform and is expressed in eyes, ocelli, brain, and male gonads. The other, dgqB, has the three novel exons and is widely expressed. Remarkably, all three nonvisual B exons are highly similar (82% identity at the amino acid level) to the Gq alpha family consensus, from Caenorhabditis elegans to human, but all three visual A exons are divergent (61% identity). Intriguingly, we have found a third isoform, dgqC, which is specifically and abundantly expressed in male gonads, and shares the divergent rhodopsin-binding exon of dgqA. We suggest that DGqC is a candidate for the light-signal transducer of a testes-autonomous photosensory clock. This proposal is supported by the finding that rhodopsin 2 and arrestin 1, two photoreceptor-cell-specific genes, are also expressed in male gonads.

An intrinsic genetic program for autonomous differentiation of muscle cells in the ascidian embryo.

The B-line presumptive muscle cells of ascidian embryos have extensive potential for self-differentiation dependent on determinants prelocalized in the myoplasm of fertilized eggs. Ascidian larval muscle cells therefore provide an experimental system with which to explore an intrinsic genetic program for autonomous specification of embryonic cells. Experiments with egg fragments suggested that maternal mRNAs are one of the components of muscle determinants. Expression of larval muscle actin genes begins as early as the 32-cell stage, prior to the developmental fate restriction of the cells. The timing of initiation of the actin gene expression proceeds the expression of an ascidian homologue of vertebrate MyoD by a few hours. Mutations in the proximal E-box of the 5' flanking region of the actin genes did not alter the promoter activity for muscle-specific expression of reporter gene. These results, together with results of deletion constructs of fusion genes, suggest that muscle determinants regulate directly, or indirectly via regulatory factors other than MyoD, the transcription of muscle-specific structural genes leading to the terminal differentiation.

Parvovirus B19 promoter at map unit 6 confers autonomous replication competence and erythroid specificity to adeno-associated virus 2 in primary human hematopoietic progenitor cells.

The pathogenic human parvovirus B19 is an autonomously replicating virus with a remarkable tropism for human erythroid progenitor cells. Although the target cell specificity for B19 infection has been suggested to be mediated by the erythrocyte P-antigen receptor (globoside), a number of nonerythroid cells that express this receptor are nonpermissive for B19 replication. To directly test the role of expression from the B19 promoter at map unit 6 (B19p6) in the erythroid cell specificity of B19, we constructed a recombinant adeno-associated virus 2 (AAV), in which the authentic AAV promoter at map unit 5 (AAVp5) was replaced by the B19p6 promoter. Although the wild-type (wt) AAV requires a helper virus for its optimal replication, we hypothesized that inserting the B19p6 promoter in a recombinant AAV would permit autonomous viral replication, but only in erythroid progenitor cells. In this report, we provide evidence that the B19p6 promoter is necessary and sufficient to impart autonomous replication competence and erythroid specificity to AAV in primary human hematopoietic progenitor cells. Thus, expression from the B19p6 promoter plays an important role in post-P-antigen receptor erythroid-cell specificity of parvovirus B19. The AAV-B19 hybrid vector system may also prove to be useful in potential gene therapy of human hemoglobinopathies.

Planificación y supervisión de flotas de robots autónomos en tareas agrícolas

El control seguro y efectivo de las malas hierbas según los principios establecidos por la Agricultura de Precisión requiere una tecnología específica, avanzada y de coste asumible dentro de los márgenes de beneficio. El uso de plataformas móviles autónomas tanto terrestres como aéreas equipadas con sistemas de percepción innovadores, sistemas inteligentes de toma de decisión y herramientas que permitan la aplicación precisa de los tratamientos herbicidas, reduce el coste asociado a la operación así como los potenciales daños ambientales y el riesgo para los agricultores. Varios son los grupos internacionales de investigación dedicados al desarrollo de tecnologías basadas en sistemas robóticos capaces de optimizar las operaciones complejas implicadas en este tipo de tratamientos de precisión. El desarrollo de sistemas autónomos de ayuda al tratamiento preciso, tanto de cultivos extensivos (malas hierbas) como de leñosos, es el objetivo principal del proyecto RHEA (Robot Fleets for Highly Effective Agriculture and Forestry Management), financiado por el 7º Programa Marco de la CE y dirigido a minimizar los insumos (agroquímicos, combustible, etc.) a la vez que garantizar la calidad y seguridad del producto así como cubrir totalmente el campo independientemente del tamaño que éste tenga. RHEA propone utilizar una flota de robots pequeños/medianos tanto aéreos como terrestres para la inspección/monitorización y posterior aplicación de fitosanitarios, lo que presenta múltiples ventajas frente al tratamiento basado en la habitual máquina de mayores dimensiones y más tradicional. Entre otras, una flota de robots de tamaño pequeño/mediano reduce el impacto sobre la compactación del suelo e interactúa de un modo más seguro con los operarios, ya que la detección e interacción se puede distribuir en varios sistemas de detección y gestión de fallos como los propuestos en la presente tesis. El trabajo de investigación presentado en esta tesis se ha desarrollado dentro de este proyecto europeo y está relacionado con el diseño, desarrollo y evaluación del nivel más alto de la arquitectura RHEA, en otras palabras, con los tres aspectos fundamentales para conseguir que los robots de la flota ejecuten el trabajo eficientemente y sin intervención humana, es decir, con la planificación, la supervisión y la gestión completa e integrada de las tareas de inspección y tratamiento...

Developing Autonomous Microgrids: A Theoretical Case Study

Microgrids are autonomously operated, geographically clustered electricity generation and distribution systems that supply power in closed system settings; they are highly compatible with renewable energy sources and distributed generation technologies. Mocrogrids are currently a serially underutilized and underappreciated commodity in the energy infrastructure portfolio worldwide. To demonstrate feasibility under poor conditions (little renewable energy potential and high demand) this capstone project develops a theoretical case study in which a renewable microgrid is employed to power rural communities of southern Montgomery County, Arkansas. Utilizing commercially manufactured 1.5-megawatt wind turbines and a 1-megawatt solar panel generation system, 4-megawatts of lithium ion battery storage, and demand response technology, a microgrid is designed that supplies 235 households with reliable electricity supply.

Estimación bayesiana de características en robots móviles mediante muestreo de la densidad a posteriori

Comunicación presentada en el I Congrés Català d’Intel·ligència Artificial, Tarragona, Octubre de 1998.

Multi-agent system for control of robots inspired on the distributed activity and hormonal regulation of humans

Robotics is an emerging field with great activity. Robotics is a field that presents several problems because it depends on a large number of disciplines, technologies, devices and tasks. Its expansion from perfectly controlled industrial environments toward open and dynamic environment presents a many new challenges. New uses are, for example, household robots or professional robots. To facilitate the low cost, rapid development of robotic systems, reusability of code, its medium and long term maintainability and robustness are required novel approaches to provide generic models and software systems who develop paradigms capable of solving these problems. For this purpose, in this paper we propose a model based on multi-agent systems inspired by the human nervous system able to transfer the control characteristics of the biological system and able to take advantage of the best properties of distributed software systems. Specifically, we model the decentralized activity and hormonal variation.

Decomposition of human behavior using model of competencies: application to robotic control system

For many years, humans and machines have shared the same physical space. To facilitate their interaction with humans, their social integration and for more rational behavior has been sought that the robots demonstrate human-like behavior. For this it is necessary to understand how human behavior is generated, discuss what tasks are performed and how relate to themselves, for subsequent implementation in robots. In this paper, we propose a model of competencies based on human neuroregulator system for analysis and decomposition of behavior into functional modules. Using this model allow separate and locate the tasks to be implemented in a robot that displays human-like behavior. As an example, we show the application of model to the autonomous movement behavior on unfamiliar environments and its implementation in various simulated and real robots with different physical configurations and physical devices of different nature. The main result of this work has been to build a model of competencies that is being used to build robotic systems capable of displaying behaviors similar to humans and consider the specific characteristics of robots.

Awareness of L1 and L2 word-formation mechanisms for the development of a more autonomous L2 learner

Unlike traditional approaches, new communicative trends disregard the role of word-formation mechanisms. They tend to focus on syntax and/or vocabulary without analyzing the mechanisms involved in the creation of lexical items. In this paper, based on the analysis of the use of prefixes by L2 learners in oral and written productions, as provided by the SULEC, we emphasize the advantages that word-formation awareness and knowledge may have for the learners in terms of production, creativity, understanding, autonomy, and proficiency. Through the teaching of word-formation learners may more easily decipher, decode and/or encode messages, create words they have never seen before, etc.

Dynamic Visual Servoing With Chaos Control for Redundant Robots

This paper presents a new dynamic visual control system for redundant robots with chaos compensation. In order to implement the visual servoing system, a new architecture is proposed that improves the system maintainability and traceability. Furthermore, high performance is obtained as a result of parallel execution of the different tasks that compose the architecture. The control component of the architecture implements a new visual servoing technique for resolving the redundancy at the acceleration level in order to guarantee the correct motion of both end-effector and joints. The controller generates the required torques for the tracking of image trajectories. However, in order to guarantee the applicability of this technique, a repetitive path tracked by the robot-end must produce a periodic joint motion. A chaos controller is integrated in the visual servoing system and the correct performance is observed in low and high velocities. Furthermore, a method to adjust the chaos controller is proposed and validated using a real three-link robot.

Learning Probabilistic Features for Robotic Navigation Using Laser Sensors

SLAM is a popular task used by robots and autonomous vehicles to build a map of an unknown environment and, at the same time, to determine their location within the map. This paper describes a SLAM-based, probabilistic robotic system able to learn the essential features of different parts of its environment. Some previous SLAM implementations had computational complexities ranging from O(Nlog(N)) to O(N2), where N is the number of map features. Unlike these methods, our approach reduces the computational complexity to O(N) by using a model to fuse the information from the sensors after applying the Bayesian paradigm. Once the training process is completed, the robot identifies and locates those areas that potentially match the sections that have been previously learned. After the training, the robot navigates and extracts a three-dimensional map of the environment using a single laser sensor. Thus, it perceives different sections of its world. In addition, in order to make our system able to be used in a low-cost robot, low-complexity algorithms that can be easily implemented on embedded processors or microcontrollers are used.

Women's Songs. The Lullaby in the Spanish Autonomous Region of Valencia

A lullaby is a song performed almost exclusively by women in all cultures to make children fall asleep. But traditional lullaby singing has declined due to social change. This study analyzes its structure and content thoroughly and aspects of this tradition providing information on usage, customs, themes and types of melody, and reflecting the importance of this form of cultural expression.

3DCOMET: 3D compression methods test dataset

The use of 3D data in mobile robotics applications provides valuable information about the robot’s environment. However usually the huge amount of 3D information is difficult to manage due to the fact that the robot storage system and computing capabilities are insufficient. Therefore, a data compression method is necessary to store and process this information while preserving as much information as possible. A few methods have been proposed to compress 3D information. Nevertheless, there does not exist a consistent public benchmark for comparing the results (compression level, distance reconstructed error, etc.) obtained with different methods. In this paper, we propose a dataset composed of a set of 3D point clouds with different structure and texture variability to evaluate the results obtained from 3D data compression methods. We also provide useful tools for comparing compression methods, using as a baseline the results obtained by existing relevant compression methods.