Human management of a robotic swarm

This paper proposes a management algorithm that allows a human operator to organize a robotic swarm via a robot leader. When the operator requests a robot to become a leader, nearby robots suspend their activities. The operator can then request a count of the robots, and assign them into subgroups, one for each task. Once the operator releases the leader, the robots perform the tasks they were assigned to. We report a series of experiments conducted with up to 30 e-puck mobile robots. On average, the counting and allocation algorithm correctly assigns 95 % of the robots in the swarm. The time to count the number of robots increases, on average, linearly with the number of robots, provided they are arranged in random formation

Growth, microstructure, and failure of crazes in glassy polymers

We report on an extensive study of craze formation in glassy polymers. Molecular dynamics simulations of a coarse-grained bead-spring model were employed to investigate the molecular level processes during craze nucleation, widening, and breakdown for a wide range of temperature, polymer chain length $N$, entanglement length $N_e$ and strength of adhesive interactions between polymer chains. Craze widening proceeds via a fibril-drawing process at constant drawing stress. The extension ratio is determined by the entanglement length, and the characteristic length of stretched chain segments in the polymer craze is $N_e/3$. In the craze, tension is mostly carried by the covalent backbone bonds, and the force distribution develops an exponential tail at large tensile forces. The failure mode of crazes changes from disentanglement to scission for $N/N_e\sim 10$, and breakdown through scission is governed by large stress fluctuations. The simulations also reveal inconsistencies with previous theoretical models of craze widening that were based on continuum level hydrodynamics

Sex-specific effects of gender identification on pain study recruitment

Epidemiological, clinical and laboratory studies show sex differences in pain responses, with women more sensitive to nociceptive stimulation and more vulnerable to long term pain conditions than men. Given evidence that males are culturally reinforced for the ability to endure (or under-report) pain, some of these findings might be explained by socio-cultural beliefs about gender-appropriate behaviour. One potential manifestation of these effects might be differential participation in pain studies, with males adhering to stereotypical masculine roles viewing participation as a way to demonstrate their masculinity. To test this possibility, we assessed gender identification in 137 healthy participants. At the end of the assessment, they were asked if they would like to participate in other research studies. Interested participants were then asked to participate in a study involving administration of pain-evoking stimulation. We compared individuals who agreed to participate in the pain study to those who declined. We observed a significant sex by participation interaction in masculine gender identification, such that males (but not females) who agreed to participate identified significantly more with masculine gender. Among masculine gender traits examined, we found that high levels of aggression and competitiveness were the strongest predictors of pain study participation. Our results suggest that male samples in pain studies might have higher levels of masculine gender identification than the wider male population. Taken together with previous findings of lower pain sensitivity (or reporting) in masculine-identifying males, these results suggest an explanation for some of the sex-related differences observed in pain responses. Perspective : To examine whether sex and gender affect willingness to participate in pain studies, we assessed gender identification in male and female participants, then attempted to recruit them to participate in a pain study. Males who agree to participate in pain studies are significantly higher in masculine gender identification than males who decline to participate or females who agree to participate. Males who agreed to participate were particularly high in aggressiveness and competitiveness

Low Energy Electron Point Projection Microscopy of Suspended Graphene, the Ultimate "Microscope Slide"

Point Projection Microscopy (PPM) is used to image suspended graphene using low-energy electrons (100-200eV). Because of the low energies used, the graphene is neither damaged or contaminated by the electron beam. The transparency of graphene is measured to be 74%, equivalent to electron transmission through a sheet as thick as twice the covalent radius of sp^2-bonded carbon. Also observed is rippling in the structure of the suspended graphene, with a wavelength of approximately 26 nm. The interference of the electron beam due to the diffraction off the edge of a graphene knife edge is observed and used to calculate a virtual source size of 4.7 +/- 0.6 Angstroms for the electron emitter. It is demonstrated that graphene can be used as both anode and substrate in PPM in order to avoid distortions due to strong field gradients around nano-scale objects. Graphene can be used to image objects suspended on the sheet using PPM, and in the future, electron holography

O vírus da queima do broto da soja no Brasil: etiologia, epidemiologia e controle.

Caracteristicas do virus; Modo de transmissao; Sintomas; Epidemiologia e controle; Distribuicao no Brasil e plantas hospedeiras; Danos e controle.bitstream/item/60659/1/Documentos-85.pd

Metastable liquid lamellar structures in binary and ternary mixtures of Lennard-Jones fluids

We have carried out extensive equilibrium molecular dynamics (MD) simulations to investigate the Liquid-Vapor coexistence in partially miscible binary and ternary mixtures of Lennard-Jones (LJ) fluids. We have studied in detail the time evolution of the density profiles and the interfacial properties in a temperature region of the phase diagram where the condensed phase is demixed. The composition of the mixtures are fixed, 50% for the binary mixture and 33.33% for the ternary mixture. The results of the simulations clearly indicate that in the range of temperatures $78 < T < 102 ^{\rm o}$K, --in the scale of argon-- the system evolves towards a metastable alternated liquid-liquid lamellar state in coexistence with its vapor phase. These states can be achieved if the initial configuration is fully disordered, that is, when the particles of the fluids are randomly placed on the sites of an FCC crystal or the system is completely mixed. As temperature decreases these states become very well defined and more stables in time. We find that below $90 ^{\rm o}$K, the alternated liquid-liquid lamellar state remains alive for 80 ns, in the scale of argon, the longest simulation we have carried out. Nonetheless, we believe that in this temperature region these states will be alive for even much longer times.Comment: 18 Latex-RevTex pages including 12 encapsulated postscript figures. Figures with better resolution available upon request. Accepted for publication in Phys. Rev. E Dec. 1st issu

Functional connectivity of the amygdala is linked to individual differences in emotional pain facilitation

The amygdala is central to emotional processing of sensory stimuli, including pain. Because recent findings suggest that individual differences in emotional processes play a part in the development of chronic pain, a better understanding of the individual patterns of functional connectivity that makes individuals susceptible to emotionally modulated facilitation of pain is needed. We therefore investigated the neural correlates of individual differences in emotional pain facilitation using resting-state functional magnetic resonance imaging (rs-fMRI) with an amygdala seed. Thirty-seven participants took part in 3 separate sessions, during which pain sensitivity was tested (session 1), participants underwent rs-fMRI (session 2), and emotional pain modulation was assessed (session 3). The amygdala served as seed for the rs-fMRI analysis, and whole-brain voxel-wise connectivity was tested. Pain modulatory scores were entered as regressor for the group analysis. Stronger connectivity of the amygdala to S1/M1, S2/operculum, and posterior parietal cortex at rest characterized individuals who showed greater pain facilitation by negative emotions. When comparing the amygdala networks associated with pain unpleasantness and with pain-intensity modulation, most of the identified areas were equally related to either pain rating type; only amygdala connectivity to S1/M1 was found to predict pain-intensity modulation specifically. We demonstrate that trait-like patterns of functional connectivity between amygdala and cortical regions involved in sensory and motor responses are associated with the individual amplitude of pain facilitation by negative emotional states. Our results are an early step toward improved understanding of the mechanisms that give rise to individual differences in emotional pain modulation

Functional architecture and specifications for Tolerancing Data and Knowledge Management

Part 1: Knowledge ManagementInternational audienceThe paper deals with the Computer-Aided Tolerancing and Product Data Management. It is especially focus on data and knowledge management system to support and improve the tolerancing tasks in product development process. The first part of the paper introduces an overview about the recent developments related to tolerancing supports and data management systems. Based on a literature survey and industrial issues, the second part proposes a functional architecture and specifications of the data and knowledge manage-ment system addressing the numerous needs clarified by tolerancing experts