The configuration multi-edge model: Assessing the effect of fixing node strengths on weighted network magnitudes

Complex networks grow subject to structural constraints which affect their measurable properties. Assessing the effect that such constraints impose on their observables is thus a crucial aspect to be taken into account in their analysis. To this end,we examine the effect of fixing the strength sequence in multi-edge networks on several network observables such as degrees, disparity, average neighbor properties and weight distribution using an ensemble approach. We provide a general method to calculate any desired weighted network metric and we show that several features detected in real data could be explained solely by structural constraints. We thus justify the need of analytical null models to be used as basis to assess the relevance of features found in real data represented in weighted network form.Comment: 11 pages. 4 figure

Co-circulation of a novel phlebovirus and Massilia virus in sandflies, Portugal

Free PMC Article: www.ncbi.nlm.nih.gov/pmc/articles/pmid/26497645/Background: In Portugal, entomological surveys to detect phleboviruses in their natural vectors have not been performed so far. Thus, the aims of the present study were to detect, isolate and characterize phleboviruses in sandfly populations of Portugal. Findings: From May to October 2007–2008, 896 female sandflies were trapped in Arrábida region, located on the southwest coast of Portugal. Phlebovirus RNA was detected by using a pan-phlebovirus RT-PCR in 4 out of 34 Phlebotomus perniciosus pools. Direct sequencing of the amplicons showed that 2 samples exhibited 72 % nucleotide identity with Arbia virus, and two showed 96 % nucleotide identity with Massilia virus. The Arbia-like virus (named Alcube virus) was isolated in cell culture and complete genomic sequences of one Alcube and two Massila viruses were determined using next-generation sequencing technology. Phylogenetic analysis demonstrated that Alcube virus clustered with members of the Salehabad virus species complex. Within this clade, Alcube virus forms a monophyletic lineage with the Arbia, Salehabad and Adana viruses sharing a common ancestor. Arbia virus has been identified as the most closely related virus with 20-28 % nucleotide and 10-27 % amino acid divergences depending on the analysed segment. Conclusions: We have provided genetic evidence for the circulation of a novel phlebovirus species named Alcube virus in Ph. perniciosus and co-circulation of Massilia virus, in Arrábida region, southwest of Portugal. Further epidemiological investigations and surveillance for sandfly-borne phleboviruses in Portugal are needed to elucidate their medical importance.This work was partially funded by the FCT project “New arboviruses isolated in Portugal. Risk assessment and public health application" (PTDC/SAU-SAP/119199/2010)

Model-assisted measurements of suspension-feeding flow velocities

Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis, measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers (Re). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re, pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8−520, and exhalant Re ranged from 15−1073. Volumetric pumping rates ranged from 1.7−7.4 l h−1 for Mya, 0.3−3.6 l h−1 for Mercenaria, and 0.07−0.97 l h−1 for Ciona. We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies

Testing the robustness of laws of polysemy and brevity versus frequency

The pioneering research of G.K. Zipf on the relationship between word frequency and other word features led to the formulation of various linguistic laws. Here we focus on a couple of them: the meaning-frequency law, i.e. the tendency of more frequent words to be more polysemous, and the law of abbreviation, i.e. the tendency of more frequent words to be shorter. Here we evaluate the robustness of these laws in contexts where they have not been explored yet to our knowledge. The recovery of the laws again in new conditions provides support for the hypothesis that they originate from abstract mechanisms.Peer ReviewedPostprint (author's final draft

The role of suction thrust in the metachronal paddles of swimming invertebrates

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Colin, S. P., Costello, J. H., Sutherland, K. R., Gemmell, B. J., Dabiri, J. O., & Du Clos, K. T. The role of suction thrust in the metachronal paddles of swimming invertebrates. Scientific Reports, 10(1), (2020): 17790, doi:10.1038/s41598-020-74745-y.An abundance of swimming animals have converged upon a common swimming strategy using multiple propulsors coordinated as metachronal waves. The shared kinematics suggest that even morphologically and systematically diverse animals use similar fluid dynamic relationships to generate swimming thrust. We quantified the kinematics and hydrodynamics of a diverse group of small swimming animals who use multiple propulsors, e.g. limbs or ctenes, which move with antiplectic metachronal waves to generate thrust. Here we show that even at these relatively small scales the bending movements of limbs and ctenes conform to the patterns observed for much larger swimming animals. We show that, like other swimming animals, the propulsors of these metachronal swimmers rely on generating negative pressure along their surfaces to generate forward thrust (i.e., suction thrust). Relying on negative pressure, as opposed to high pushing pressure, facilitates metachronal waves and enables these swimmers to exploit readily produced hydrodynamic structures. Understanding the role of negative pressure fields in metachronal swimmers may provide clues about the hydrodynamic traits shared by swimming and flying animals.This work was funded by National Science Foundation (NSF OCE 1829913 to SPC), the Alfred P. Sloan Foundation (to BJG) and the Gordon and Betty Moore Foundation (8835 to KRS). The work was also supported by the Roger Williams Foundation to Promote Scholarship and Teaching

Neuromuscular and Perceptual Responses to Sub-Maximal Eccentric Cycling

ObjectiveEccentric (ECC) cycle-ergometers have recently become commercially-available, offering a novel method for rehabilitation training. Many studies have reported that ECC cycling enables the development of higher levels of muscular force at lower cardiorespiratory and metabolic loads, leading to greater force enhancements after a training period. However, fewer studies have focused on the specific perceptual and neuromuscular changes. As the two latter aspects are of major interest in clinical settings, this review aimed to present an overview of the current literature centered on the neuromuscular and perceptual responses to submaximal ECC cycling in comparison to concentric (CON) cycling.DesignNarrative review of the literature.ResultsAt a given mechanical workload, muscle activation is lower in ECC than in CON while the characteristics of the musculo-articular system (i.e., muscle-tendon unit, fascicle, and tendinous tissue length) are quite similar. At a given heart rate or oxygen consumption, ECC cycling training results in greater muscular hypertrophy and strength gains than CON cycling. On the contrary, CON cycling training seems to enhance more markers of muscle aerobic metabolism than ECC cycling performed at the same heart rate intensity. Data concerning perceptual responses, and neuromuscular mechanisms leading to a lower muscle activation (i.e., neural commands from cortex to muscular system) at a given mechanical workload are scarce.ConclusionEven though ECC cycling appears to be a very useful tool for rehabilitation purposes the perceptual and neural commands from cortex to muscular system during exercise need to be further studied

Dual-arm dexterous mobile manipulator with new omnidirectional wheels

[ES] Este artículo describe un manipulador móvil, bimanual y con capacidad de manipulación diestra denominado MADAR (de Mobile Anthropomorphic Dual-Arm Robot). Básicamente puede dividirse en dos partes, una base móvil y una estructura superior portando dos brazos en configuración antropomorfa con manos mecánicas diestras equipadas con sensores táctiles. La base, completamente de desarrollo propio, es de forma circular y tiene tres ruedas con un diseño novedoso que permiten una movilidad omnidireccional. La estructura superior integra elementos comerciales, como los brazos, las manos y distintos sensores, que han sido adaptados para su funcionamiento conjunto. El artículo incluye tanto la descripción de los principales elementos del hardware como del software desarrollado para su control y uso.[EN] This article describes a mobile manipulator, equipped with two arms with dexterous capabilities, called MADAR (from Mobile Anthropomorphic Dual-Arm Robot). Basically, the manipulator can be divided into two parts, a mobile base and an upper structure that includes two arms with dexterous hands equipped with tactile sensors. The base, completely self-developed, is circular in shape and has three wheels with a novel design that allow omnidirectional mobility. The upper structure integrates commercial elements, such as the arms, the hands and dierent sensors. The article includes the description of the main elements of the hardware and the software developed for its control and use.Este trabajo ha sido parcialmente financiado por el gobierno español mediante el proyecto DPI2016-80077-R.Suárez, R.; Palomo-Avellaneda, L.; Martínez, J.; Clos, D.; García, N. (2020). Manipulador móvil, bibrazo y diestro con nuevas ruedas omnidireccionales. Revista Iberoamericana de Automática e Informática industrial. 17(1):10-21. https://doi.org/10.4995/riai.2019.11422OJS1021171ABB, Jan. 2018. YuMi. www.abb.com/yumi, visitado el 2019/02/12.Adascalitei, F., Doroftei, I., Jan. 2011. Practical applications for mobile robots based on mecanum wheels - a systematic survey. Romanian Review Precision Mechanics, Optics and Mechatronics, 21-29.Adept, Jan. 2018. Pioneer manipulator. https://www.generationrobots.com/media/PioneerManipulatordatasheet.pdf.Albu-Schöffer, A., Haddadin, S., Ott, C., Stemmer, A., Wimböck, T., Hirzinger, G., May 2007. The DLR lightweight robot: Design and control concepts for robots in human environments. Industrial Robot: An Int. J. 34 (5), 376-385. https://doi.org/10.1108/01439910710774386Andersen, T., 2015. Optimizing the Universal Robots ROS driver. Tech. rep., Technical University of Denmark, Department of Electrical Engineering.Arthur Ketels and M.J.G. van den Molengraft, 2014. Open ethercat society: Home of soem and soes. openethercatsociety.github.io, visitado el 2019/02/12.Batlle, J., Barjau, A., 2009. Holonomy in mobile robots. Robotics and Auton. Systems 57 (4), 433 - 440. https://doi.org/10.1016/j.robot.2008.06.001Batlle, J., Font-Llagunes, J., Barjau, A., Jan. 2010. Calibration for mobile robots with an invariant Jacobian. Robotics and Auton. Systems 58, 10-15. https://doi.org/10.1016/j.robot.2009.09.002Bischoff, R., Huggenberger, U., Prassler, E., May 2011. KUKA youBot - A mobile manipulator for research and education. In: Proc. IEEE Int. Conf. Robotics and Automation. pp. 1-4. https://doi.org/10.1109/ICRA.2011.5980575Bridgwater, L., A. Ihrke, C., Diftler, M., Abdallah, M., Radford, N., Rogers, J., Yayathi, S., S. Askew, R., M. Linn, D., 05 2012. The robonaut 2 handdesigned to do work with tools. In: Proceedings - IEEE International Conference on Robotics and Automation. pp. 3425-3430. https://doi.org/10.1109/ICRA.2012.6224772Butterfass, J., Fischer, M., Grebenstein, M., Haidacher, S., Hirzinger, G., 2004. Design and experiences with DLR hand II. In: Proc. of World Automation Congress. Vol. 15. pp. 105-110.Clos, D., Martı́nez, J., 2015. Omnidirectional wheel, and omnidirectional mobile device. World Intellectual Property Organization (Patent WO 2015/121521 A1, lens.org/084-354-767-767-633).Company, S. R., 2015. Shadow Robot Company. Shadow Dexterous Hand. [Online] http://www.shadowrobot.com.Dean-Leon, E., Pierce, B., Bergner, F., Mittendorfer, P., Ramirez-Amaro, K., Burger, W., Cheng, G., 2017. TOMM: Tactile omnidirectional mobile manipulator. In: Proc. IEEE Int. Conf. Robotics and Autom. pp. 2441-2447. https://doi.org/10.1109/ICRA.2017.7989284Fentanes, J. P., Zalama, E., Garc'ıa-Bermejo, J. G., 2012. Plataforma robótica para tareas de reconstrucci'on tridimensional de entornos exteriores. Revista Iberoamericana de Automática e Informática industrial 9 (1), 81-82. https://doi.org/10.1016/j.riai.2011.11.009Ferriere, L., Raucent, B., May 1998. ROLLMOBS, a new universal wheel concept. In: Proc. IEEE Int. Conf. Robotics and Automation. Vol. 3. pp. 1877-1882.Fitzgerald, C., Apr. 2013. Developing baxter. In: Proc. IEEE Int. Conf. Technologies for Practical Robot Appl. pp. 1-6. https://doi.org/10.1109/TePRA.2013.6556344Garcı́a, N., Rosell, J., Suárez, R., 2017. Motion planning by demonstration with human-likeness evaluation for dual-arm robots. IEEE Trans. Systems, Man, and Cybernetics: Systems PP (99), 1-10. https://doi.org/10.1109/TSMC.2017.2756856Gerum, P., 2004. Xenomai-Implementing a RTOS emulation framework on GNU/Linux. https://xenomai.org/documentation/xenomai-2.1/pdf/xenomai.pdf, visitado el 2019/05/31.Hermann, A., Sun, J., Xue, Z., Rühl, S. W., Oberländer, J., Roennau, A., Zöllner, J. M., Dillmann, R., July 2013. Hardware and software architecture of the bimanual mobile manipulation robot hollie and its actuated upper body. In: 2013 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM). Wollongong, NSW, Australia, pp. 286-292. https://doi.org/10.1109/AIM.2013.6584106IOC Robotics Lab, 2014. SOEM for RTNET and Xenomai. github.com/iocroblab/soem, visitado el 2019/02/12.Khatib, O., 1999. Mobile manipulation: The robotic as-sistant. Robotics and Auton. Systems 26 (2), 175 - 183. https://doi.org/10.1016/S0921-8890(98)00067-0Kröger, T., May 2011. Opening the door to new sensor-based robot applications - The Reflexxes Motion Libraries. In: IEEE Int. Conf. Robotics and Automation. pp. 1-4. https://doi.org/10.1109/ICRA.2011.5980578Kuka Robotics, 2018. KMR iiwa. www.kuka.com/en-us/products/mobility/mobile-robot-systems/kmr-iiwa, visitado el 2019/02/12.Kurazume, R., Hasegawa, T., Oct 2006. A new index of serial-link manipulator performance combining dynamic manipulability and manipulating force ellipsoids. IEEE Trans. Robotics 22 (5), 1022-1028. https://doi.org/10.1109/TRO.2006.878949Lind, M., Schrimpf, J., Ulleberg, T., 2010. Open real-time robot controller framework. In: Proc. CIRP Conf. Assembly Technology and Systems - Responsive, customer demand driven, adaptive assembly. pp. 13-18.Montaño, A., Suárez, R., 2015. Unknown object manipulation based on tactile information. In: IEEE/RSJ Int. Conf. Intelligent Robots and Systems. pp. 5642-5647. https://doi.org/10.1109/IROS.2015.7354178Montaño, A., Suárez, R., Oct 2018a. Improving grasping forces during the manipulation of unknown objects. In: 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). pp. 3490-3495. https://doi.org/10.1109/IROS.2018.8593655Montaño, A., Suárez, R., 2018b. Manipulation of unknown objects to improve the grasp quality using tactile information. Sensors 18 (5-1412). https://doi.org/10.3390/s18051412PAL Robotics, Jan. 2018. Tiago. tiago.pal-robotics.com, visitado el 2019/02/12.Pozyx NV, 2018. Creator Pozyx. www.pozyx.io, visitado el 2019/02/12.Quigley, M., Conley, K., Gerkey, B. P., Faust, J., Foote, T., Leibs, J., Wheeler, R., Ng, A. Y., 2009. Ros: an open-source robot operating system. In: ICRA Workshop on Open Source Software.Reitelshöfer, S., Ramer, C., Gräf, D., Matern, F., Franke, J., Dec. 2014. Combining a collaborative robot and a lightweight Jamming-Gripper to realize an intuitively to use and flexible co-worker. In: Proc. IEEE/SICE Int. Symp. System Integration. pp. 1-5. https://doi.org/10.1109/SII.2014.7028001Roa, M., Suárez, R., Cornellà, J., 2008. Medidas de calidad para la prensión de objetos. Revista Iberoamericana de Automática e Informatica Industrial, RIAI 5 (1), 66-82. https://doi.org/10.1016/S1697-7912(08)70124-9Rojas-de-Silva, A., Suárez, R., 2016. Grasping bulky objects with two anthropomorphic hands. In: IEEE/RSJ Int. Conf. Intelligent Robots and Systems. pp. 877-884. https://doi.org/10.1109/IROS.2016.7759154ROS-I Consortium, 2012. ROS-Industrial. rosindustrial.org/, visitado el 2019/02/12.Rosell, J., Pérez, A., Aliakbar, A., Muhayyuddin, Palomo, L., Garcı́a, N., Sept. 2014. The Kautham Project: A teaching and research tool for robot motion planning. In: Proc. IEEE Int. Conf. Emerging Technologies and Factory Automation. https://doi.org/10.1109/ETFA.2014.7005143Runge, G., Borchert, G., Raatz, A., Sept 2014. Design of a holonomic ball drive for mobile robots. In: Proc. IEEE/ASME Int. Conf. Mechatronic and Embedded Systems and Applications. pp. 1-6. https://doi.org/10.1109/MESA.2014.6935568Sadun, A. S., Jalani, J., Jamil, F., Sep. 2016. Grasping analysis for a 3-finger adaptive robot gripper. In: 2016 2nd IEEE International Symposium on Robotics and Manufacturing Automation (ROMA). pp. 1-6. https://doi.org/10.1109/ROMA.2016.7847806SCHUNK GmbH, 2011. Shunk dexterous hand - SDH2. schunk.com/us_en/gripping-systems/series/sdh/, visitado el 2019/02/12.SICK Vertriebs-GmbH, 2018. TiM5xx. www.sick.com/de/en/detection-and-ranging-solutions/2d-lidar-sensors/tim5xx/tim561-2050101/p/p369446, visitado el 2019/02/12.SimLab-Wonik Robotics, Set. 2012. Allegro hand is a low-cost and highly adaptive robotic hand. www.simlab.co.kr/Allegro-Hand.htm, visitadoel 2019/02/12.Suárez, R., Grosch, P., Jul 2004. Dexterous robotic hand ma-i, sofware and hardware architecture. In: Intelligent Manipulation and Grasping International Conference, IMG'04. pp. 91-96.Suárez, R., Rosell, J., Garcı́a, N., May 2015. Using synergies in dual-arm manipulation tasks. In: Proc. IEEE Int. Conf. Robotics and Automation. pp. 5655-5661. https://doi.org/10.1109/ICRA.2015.7139991Suárez, R., Palomo-Avellaneda, L., Martinez, J., Clos, D., Garcı́a, N., 2018.Development of a dexterous dual-arm omnidirectional mobile manipulator. IFAC-PapersOnLine 51 (22), 126 - 131, 12th IFAC Symposium on Robot Control SYROCO 2018. https://doi.org/10.1016/j.ifacol.2018.11.529SYNTENET, 2014. Projecto: Sincronización y teleoperación con interacción visual 3d de redes de manipuladores móviles y robots con articulaciones flexibles. Referencia: DPI2011-22471, Perido: 01/01/2012 al 31/12/2014, IP: Luis Basañez, IOC-UPC.Universal Robots, Feb. 2019. Ur5 collaborative robot arm. www.universal-robots.com/products/ur5-robot, visitado el 2019/02/12.Weiss Robotics, 2015. WTS-FT; Weiss Robotics GmbH&Co.KG. www.weiss-robotics.com/en/produkte/tactile-sensing/wts-ft-en/, visitado el 2019/02/12.Willow Garage, 2010. Willow Garage PR2. http://www.willowgarage.com/pages/pr2/overview, visitado el 2019/06/06

Replica theory for learning curves for Gaussian processes on random graphs

Statistical physics approaches can be used to derive accurate predictions for the performance of inference methods learning from potentially noisy data, as quantified by the learning curve defined as the average error versus number of training examples. We analyse a challenging problem in the area of non-parametric inference where an effectively infinite number of parameters has to be learned, specifically Gaussian process regression. When the inputs are vertices on a random graph and the outputs noisy function values, we show that replica techniques can be used to obtain exact performance predictions in the limit of large graphs. The covariance of the Gaussian process prior is defined by a random walk kernel, the discrete analogue of squared exponential kernels on continuous spaces. Conventionally this kernel is normalised only globally, so that the prior variance can differ between vertices; as a more principled alternative we consider local normalisation, where the prior variance is uniform