Architecture for real-time coordination of multiple autonomous mobile units

Interest on using teams of mobile robots has been growing, due to their potential to cooperate for diverse purposes, such as rescue, de-mining, surveillance or even games such as robotic soccer. These applications require a real-time middleware and wireless communication protocol that can support an efficient and timely fusion of the perception data from different robots as well as the development of coordinated behaviours. Coordinating several autonomous robots towards achieving a common goal is currently a topic of high interest, which can be found in many application domains. Despite these different application domains, the technical problem of building an infrastructure to support the integration of the distributed perception and subsequent coordinated action is similar. This problem becomes tougher with stronger system dynamics, e.g., when the robots move faster or interact with fast objects, leading to tighter real-time constraints. This thesis work addressed computing architectures and wireless communication protocols to support efficient information sharing and coordination strategies taking into account the real-time nature of robot activities. The thesis makes two main claims. Firstly, we claim that despite the use of a wireless communication protocol that includes arbitration mechanisms, the self-organization of the team communications in a dynamic round that also accounts for variable team membership, effectively reduces collisions within the team, independently of its current composition, significantly improving the quality of the communications. We will validate this claim in terms of packet losses and communication latency. We show how such self-organization of the communications can be achieved in an efficient way with the Reconfigurable and Adaptive TDMA protocol. Secondly, we claim that the development of distributed perception, cooperation and coordinated action for teams of mobile robots can be simplified by using a shared memory middleware that replicates in each cooperating robot all necessary remote data, the Real-Time Database (RTDB) middleware. These remote data copies, which are updated in the background by the selforganizing communications protocol, are extended with age information automatically computed by the middleware and are locally accessible through fast primitives. We validate our claim showing a parsimonious use of the communication medium, improved timing information with respect to the shared data and the simplicity of use and effectiveness of the proposed middleware shown in several use cases, reinforced with a reasonable impact in the Middle Size League of RoboCup.

Mécanismes neuronaux médullaires, coordination musculaire et fonction motrice chez les sujets hémiparétiques

Dans l’hémiparésie consécutive à un AVC, une coactivation anormale des extenseurs du genou et de la cheville est souvent observée à la jambe atteinte lorsque la personne tente de bouger ou encore lors de la marche. Les mécanismes sous-jacents à cette coactivation sont mal compris. Bien que l’AVC entraîne une lésion supraspinale, des évidences démontrent le dysfonctionnement de certains circuits spinaux dans l’hémiparésie. Ce projet de doctorat visait à évaluer : 1) l’excitabilité des circuits spinaux intersegmentaires projetant des extenseurs du genou aux extenseurs de la cheville et 2) si un éventuel dysfonctionnement de ces circuits dans l’hémiparésie est associé à une coactivation anormale des extenseurs du genou et de la cheville lors de contractions statiques et au cours de la marche. La première étude compare la modulation de l’activité réflexe du soléaire suite à la stimulation du nerf fémoral entre des sujets hémiparétiques et sains. Une augmentation de la facilitation hétéronyme de courte latence et une diminution de l’inhibition ultérieure du réflexe H du soléaire ont été observées chez les sujets hémiparétiques. Ces résultats démontrent un dysfonctionnement des circuits intersegmentaires propriospinaux liant le quadriceps au soléaire suite à l’AVC. La deuxième étude démontre que ces changements dans la modulation hétéronyme des sujets hémiparétiques, évaluée au moyen de la méthode complexe basée sur l’activité réflexe du soléaire, sont similaires à ceux observés lorsque la modulation est évaluée en utilisant une méthode plus simple, soit celle de l’activité volontaire du soléaire. De plus, la modulation hétéronyme évaluée par les deux méthodes est corrélée avec l’atteinte motrice à la jambe parétique. La troisième étude a permis de quantifier une augmentation de la coactivation entre les extenseurs du genou et de la cheville lors de contractions volontaires statiques chez des personnes hémiparétiques par rapport à des personnes saines. De plus, le niveau accru de la coactivation involontaire des extenseurs de la cheville lors de l’activation volontaire des extenseurs du genou s’avère corrélé avec la modulation intersegmentaire du côté parétique. La quatrième étude a utilisé un indice temporel, soit l’intervalle entre les pics d’activation électromyographique (PAI), et un indice d’amplitude de coactivation (CAI) pour quantifier une augmentation de la coactivation entre les extenseurs du genou et de la cheville lors de la marche chez des personnes hémiparétiques par rapport à des personnes saines. Ces indices sont corrélés, pour certains groupes musculaires, avec la modulation intersegmentaire modifiée du côté parétique. Finalement, des résultats préliminaires montrent que la vibration mécanique du tendon rotulien (80 Hz) réduit la facilitation intersegmentaire accrue des sujets hémiparétiques. Ce projet doctoral a permis de mettre en lumière un dysfonctionnement de circuits spinaux liant le quadriceps et le soléaire dans l’hémiparésie consécutive à un AVC. Ce changement dans les mécanismes neurophysiologiques de la moelle épinière est corrélé avec des changements fonctionnels. Ainsi, ce dysfonctionnement pourrait contribuer à la coactivation involontaire entre les extenseurs du genou et de la cheville qui fait partie intégrante de la synergie pathologique en extension souvent rencontrée à la jambe parétique lors d’efforts en statique et pendant la marche. Finalement, une étude préliminaire suggère que la vibration mécanique serait une modalité sensorielle prometteuse pour réguler l’hyperexcitabilité des circuits spinaux qui contribuerait aux atteintes motrices chez les personnes hémiparétiques.

Coordination and control in project-based work: digital objects and infrastructures for delivery

A major infrastructure project is used to investigate the role of digital objects in the coordination of engineering design work. From a practice-based perspective, research emphasizes objects as important in enabling cooperative knowledge work and knowledge sharing. The term ‘boundary object’ has become used in the analysis of mutual and reciprocal knowledge sharing around physical and digital objects. The aim is to extend this work by analysing the introduction of an extranet into the public–private partnership project used to construct a new motorway. Multiple categories of digital objects are mobilized in coordination across heterogeneous, cross-organizational groups. The main findings are that digital objects provide mechanisms for accountability and control, as well as for mutual and reciprocal knowledge sharing; and that different types of objects are nested, forming a digital infrastructure for project delivery. Reconceptualizing boundary objects as a digital infrastructure for delivery has practical implications for management practices on large projects and for the use of digital tools, such as building information models, in construction. It provides a starting point for future research into the changing nature of digitally enabled coordination in project-based work.

Molecular mechanisms of oestrogen action on growth of human breast cancer cells in culture

Growth responses to oestrogen can be reproducibly obtained using a selection of oestrogen-receptor-containing human breast cancer cell lines, and molecular mechanisms have been shown to include modulation to growth factor/receptor/signalling pathways, cell-cycle proteins, apoptosis, differentiation, adhesion, motility and migration. Considerable progress has been made in understanding the molecular basis of oestrogen action on gene expression through the ligand-activated transcription factors human oestrogen receptor α (ERα) and ERβ and the resulting effects on global gene expression patterns, but the full profile of coordination of the alterations, which brings about changes in cell growth through genomic and non-genomic mechanisms remain to be fully elucidated. Oestrogen regulation of cell growth involves a complex cross-talk between oestrogen receptor and growth factor signalling pathways such that inhibition of one pathway may lead to stimulation of another, which may explain the remarkable ability of human breast cancer cells to escape from any mode of imposed growth inhibition be it oestrogen deprivation or administration of antioestrogen. Although studies on cell growth have focused to date on the effects of physiological oestrogens, many hundreds of environmental chemicals with oestrogenic properties have now been measured in the human breast. Whether or not the weight of evidence eventually establishes any causal link of complex mixtures of environmental oestrogenic chemicals with breast cancer, the presence of so many oestrogenic chemicals in the breast must influence resulting oestrogenic responses, and the impact of this additional oestrogenic burden needs to be taken into account in future studies on growth regulation of human breast cancer cells.

Online motor control in children with developmental coordination disorder: chronometric analysis of double-step reaching performance

Background
Although there are a number of plausible accounts to explain movement clumsiness in children [or developmental coordination disorder (DCD)], the cause(s) of the disorder remain(s) an issue of debate. One aspect of motor control that is particularly important to the fluid expression of skill is rapid online control (ROC). Data on DCD have been conflicting. While some recent work using double-step reaching suggests no difficulty in online control, others suggest deficits (e.g. based on sequential pointing). To help resolve this debate, we suggest two things: use of recent neuro-computational models as a framework for investigating motor control in DCD, and more rigorous investigation of double-step reaching. Our working assumption here is that ROC is only viable through the seamless integration of predictive (or forward) models of movement and feedback-based mechanisms.

Aim
The aim of this chronometric study was to explore ROC in children with DCD using a double-step reaching paradigm. We predicted slower online adjustments in DCD based on the argument that these children manifest a core difficulty in predictive control.

Methods
Participants were a group of 17 children with DCD and 27 typically developing children aged between 7 and 12 years. Visual targets were presented on a 17-inch LCD touch screen, inclined to an angle of 15° from horizontal. The children were instructed to press each target as it appeared as quickly and accurately as possible. For 80% of the trials, the central target location remained unchanged for the duration of the movement (non-jump trials), while for the remaining 20% of trials, the target jumped at movement onset to one of the two peripheral locations (jump trials). Reaction time (RT), movement time (MT) and reaching errors were recorded.

Results
For both groups, RT did not vary according to trial condition, while children with DCD were slower to initiate movement. Further, the MT of children with DCD was prolonged to a far greater extent on jump trials relative to controls, with a large effect size. As well, children with DCD committed significantly more errors, notably a reduced ability to inhibit central responses on jump trials.

Conclusion
Our findings help reconcile some disparate findings in the literature using similar tasks. The pattern of performance in children with DCD suggests impairment in the ability to make rapid online adjustments that are based on a predictive (or internal) model of the action. These results pave the way for future kinematic investigation.

Ligand-rare-earth ion energy transfer in coordination compounds. A theoretical approach

A theoretical approach to the energy transfer process that occurs between a ligand and a rare-earth ion in luminescent complexes is presented. A discussion on the energy transfer mechanisms involved and on the associated selection rules is made. Numerical estimates are also presented.

Energy-transfer mechanisms and emission quantum yields in Eu3+-based siloxane-poly(oxyethylene) nanohybrids

We report the energy-transfer mechanisms and emission quantum yield measurements of sol-gel-derived Eu3+-based nanohybrids. The matrix of these materials, classified as diureasils and termed U(2000) and U(600), includes urea cross-links between a siliceous backbone and polyether-based segments of two molecular weights, 2000 and 600, respectively. These materials are full-color emitters in which the Eu3+ (5)Do --> F-7(0-4) lines merge with the broad green-blue emission of the nanoscopic matrix's backbone. The excitation spectra show the presence of a large broad band (similar to 27000-29000 cm(-1)) undoubtedly assigned to a ligand-to-metal charge-transfer state. Emission quantum yields range from 2% to 13.0% depending on the polymer molecular weight and Eu3+ concentration. Energy transfer between the hybrid hosts and the cations arises from two different and independent processes: the charge-transfer band and energy transfer from the hybrid's emitting centers. The activation of the latter mechanisms induces a decrease in the emission quantum yields (relative to undoped nanohybrids) and permits a fine-tuning of the emission chromaticity across the Comission Internacionalle d'Eclairage diagram, e.g., (x, y) color coordinates from (0.21, 0.24) to (0.39, 0.36). Moreover, that activation depends noticeably on the ion local coordination. For the diureasils with longer polymer chains, energy transfer occurs as the Eu3+ coordination involves the carbonyl-type oxygen atoms of the urea bridges, which are located near the hybrid's host emitting centers. on the contrary, in the U(600)-based diureasils, the Eu3+ ions are coordinated to the polymer chains, and therefore, the distance between the hybrid's emitting centers and the metal ions is large enough to allow efficient energy-transfer mechanisms.

Foundations of macroeconomic policy coordination: fostering dialogue as a policy tool in Latin America

Includes bibliography

Grip and load force coordination in cyclical isometric manipulation task is not affected by the feedback type

Background: The relationship between normal and tangential force components (grip force - GF and load force - LF, respectively) acting on the digits-object interface during object manipulation reveals neural mechanisms involved in movement control. Here, we examined whether the feedback type provided to the participants during exertion of LF would influence GF-LF coordination and task performance. Methods. Sixteen young (24.7 ±3.8 years-old) volunteers isometrically exerted continuously sinusoidal FZ (vertical component of LF) by pulling a fixed instrumented handle up and relaxing under two feedback conditions: targeting and tracking. In targeting condition, FZ exertion range was determined by horizontal lines representing the upper (10 N) and lower (1 N) targets, with frequency (0.77 or 1.53 Hz) dictated by a metronome. In tracking condition, a sinusoidal template set at similar frequencies and range was presented and should be superposed by the participants' exerted FZ. Task performance was assessed by absolute errors at peaks (AEPeak) and valleys (AEValley) and GF-LF coordination by GF-LF ratios, maximum cross-correlation coefficients (r max), and time lags. Results: The results revealed no effect of feedback and no feedback by frequency interaction on any variable. AE Peak and GF-LF ratio were higher and rmax lower at 1.53 Hz than at 0.77 Hz. Conclusion: These findings indicate that the type of feedback does not influence task performance and GF-LF coordination. Therefore, we recommend the use of tracking tasks when assessing GF-LF coordination during isometric LF exertion in externally fixed instrumented handles because they are easier to understand and provide additional indices (e.g., RMSE) of voluntary force control. © 2013 Pedão et al.; licensee BioMed Central Ltd.

Criteria for the efficient coordination of the activities for data collection and the design of instruments for mapping and data collection applicable to countries of the Caribbean

Includes bibliography

A comparison of charge-transfer mechanisms at rotated disk electrode for biomimetic binuclear and tetranuclear oxo-manganese complex in aqueous solution

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Thermal analysis of coordination compounds. Part 3. Thermal decomposition of platinum complexes containing triphenylphosphine, triphenylarsine and triphenylstibine

Studies by thermogravimetric analysis (TG) and differential thermal analysis (DTA) of the complexes [PtCl2L2] (L is PPh3, AsPh3, SbPh3), [PtLn] (n = 3, L is SbPh3; n = 4, L is PPh3, AsPh3); [(PtL3)2N2]; [(PtL3)2C2] and [Pt(CO)2L2] (L is SbPh3) are described. Analysis of the TG and DTA curves showed that Pt(II) complexes of the type [PtCl2L2] have a higher thermal stability than the corresponding Pt(0) complexes of the type [PtLn], with the exception of [Pt(SbPh3)3], which is more stable than [PtCl2(SbPh3)2]. Thermal stabilities of each of the complexes are compared with those of the others in the series. Mechanisms of thermal decomposition of complexes of the types [PtCl2L2] and [PtLn] are proposed. Residues of the samples were characterized by chemical tests and IR spectroscopy. The residue from the thermal decomposition of [PtCl2L2] (L is PPh3, AsPh3) and [Pt(PPh3)4] is metallic platinum. For [Pt(AsPh3)4] the residue is a mixture of Pt and As, whereas for the complexes containing SbPh3 the residues are mixtures of Pt and Sb. In these cases, the proportional contents of Pt and As or Pt and Sb correspond to the stoichiometry of these elements in the respective complexes. The complexes {[Pt(SbPh3)3]2N2}, {[Pt(SbPh3)3]2C2} lose N2 or the ethynediyl group at 130-150°C and are transformed into [Pt(SbPh3)3]. © 1995.

CROSS-SECTORAL COORDINATION OF DISASTER RELIEF

Coordinating organizational activity across different sectors is crucial in disaster management. We analysed the response of 291 aid workers to the Haiti earthquake in 2010 and found that common incentives and a high degree of equality among aid organizations positively affected perceived network coordination. Large and public organizations were more likely to take leadership roles and high numbers of public organizations involved in the disaster response network led to improved network coordination. These results indicate the need for mechanisms that enable smaller and non-profit organizations to participate in network coordination and leadership.

Intracerebroventricularly delivered VEGF promotes contralesional corticorubral plasticity after focal cerebral ischemia via mechanisms involving anti-inflammatory actions

Vascular endothelial growth factor (VEGF) has potent angiogenic and neuroprotective effects in the ischemic brain. Its effect on axonal plasticity and neurological recovery in the post-acute stroke phase was unknown. Using behavioral tests combined with anterograde tract tracing studies and with immunohistochemical and molecular biological experiments, we examined effects of a delayed i.c.v. delivery of recombinant human VEGF(165), starting 3 days after stroke, on functional neurological recovery, corticorubral plasticity and inflammatory brain responses in mice submitted to 30 min of middle cerebral artery occlusion. We herein show that the slowly progressive functional improvements of motor grip strength and coordination, which are induced by VEGF, are accompanied by enhanced sprouting of contralesional corticorubral fibres that branched off the pyramidal tract in order to cross the midline and innervate the ipsilesional parvocellular red nucleus. Infiltrates of CD45+ leukocytes were noticed in the ischemic striatum of vehicle-treated mice that closely corresponded to areas exhibiting Iba-1+ activated microglia. VEGF attenuated the CD45+ leukocyte infiltrates at 14 but not 30 days post ischemia and diminished the microglial activation. Notably, the VEGF-induced anti-inflammatory effect of VEGF was associated with a downregulation of a broad set of inflammatory cytokines and chemokines in both brain hemispheres. These data suggest a link between VEGF's immunosuppressive and plasticity-promoting actions that may be important for successful brain remodeling. Accordingly, growth factors with anti-inflammatory action may be promising therapeutics in the post-acute stroke phase.