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Network dynamical systems are often characterized by the interlaced evolution of the node and edge dynamics, which are driven by both deterministic and stochastic factors. This manuscript offers a general mathematical model of coevolving network, which associates a state variable to each node and edge in the network, and describes their evolution through coupled stochastic differential equations. We study the emergence of synchronization, be it spontaneous or induced by a pinning control action, and provide sufficient conditions for local and global convergence. We enable the use of the Master Stability Function approach for studying coevolving networks, thereby obtaining conditions for almost sure local exponential convergence, whereas global conditions are derived using a Lyapunov-based approach. The theoretical results are then leveraged to design synchronization and pinning control protocols in two select applications. In the first one, the edge dynamics are tailored to induce spontaneous synchronization, whereas in the second the pinning edges are activated/deactivated and their weights modulated to drive the network towards the pinner's trajectory in a distributed fashion. [ABSTRACT FROM AUTHOR]

The topic of this manuscript is the stability analysis of continuous-time switched nonlinear systems with constraints on the admissible switching signals. Our particular focus lies in considering signals characterized by upper and lower bounds on the length of the switching intervals. We adapt and extend the existing theory of multiple Lyapunov functions, providing converse results and thus a complete characterization of uniform stability for this class of systems. We specify our results in the context of switched linear systems, providing the equivalence of exponential stability and the existence of multiple Lyapunov norms. By restricting the class of candidate Lyapunov functions to the set of quadratic functions, we are able to provide semidefinite-optimization-based numerical schemes to check the proposed conditions. We provide numerical examples to illustrate our approach and highlight its advantages over existing methods. [ABSTRACT FROM AUTHOR]

This paper presents novel stabilizability conditions for switched linear systems with arbitrary and uncontrollable underlying switching signals. We distinguish and study two particular settings: (i) the robust case, in which the active mode is completely unknown and unobservable, and (ii) the mode-dependent case, in which the controller depends on the current active switching mode. The technical developments are based on graph-theory tools, relying in particular on the path-complete Lyapunov functions framework. The main idea is to use directed and labeled graphs to encode Lyapunov inequalities to design robust and mode-dependent piecewise linear state-feedback controllers. This results in novel and flexible conditions, with the particular feature of being in the form of linear matrix inequalities (LMIs). Our technique thus provides a first controller-design strategy allowing piecewise linear feedback maps and piecewise quadratic (control) Lyapunov functions by means of semidefinite programming. Numerical examples illustrate the application of the proposed techniques, the relations between the graph order, the robustness, and the performance of the closed loop. [ABSTRACT FROM AUTHOR]

When steering the dynamics of network systems, the control design needs to cope with constraints on actuation and sensing, which often imply that the same control input is injected to each node in a given subset, and this input signal is a function of the state of this node subset. This common situation cannot be modeled in terms of standard pairwise interactions on digraphs, and we propose to use directed hypergraphs as the mathematical object suitable to describe this kind of directed, multibody interactions. We apply this framework to the pinning control problem in networks of coupled linear systems, and derive necessary and sufficient conditions for convergence onto the desired trajectory set by the pinner. Furthermore, we provide a dedicated control algorithm to identify the interconnections that are critical for network control. [ABSTRACT FROM AUTHOR]

Eco-genetic models describe the contemporary evolution of quantitative genetic traits by integrating the key ecological aspects with the modes of inheritance. Because of the flexibility in incorporating physiological, ecological, and genetic detail, eco-genetic models are typically individual-based and stochastic. Here we propose a deterministic eco-genetic population model to study the evolution of maturation schedules in exploited fish stocks. It is the first deterministic model addressing the evolution of the probabilistic maturation reaction norm (PMRN)—the genetic trait recognized to control maturation in fish species. The PMRN is the probability of interseasonal maturation as a function of age and size of juvenile individuals. Being independent of the growth trajectory followed by the individual, it can be considered a non-plastic phenotype, under limited change in temperature and climate. We consider the continuous age and size structures of the fish stock and explicitly represent foraging on a single food resource and mating under 1:1 sex ratio. Inheritance follows a single-locus-two-alleles Mendelian rule to limit the number of genotypes. We adapt the standard escalator boxcar train method for the simulation of physiologically structured population models to the case of two-dimensional age distributions—mature individuals being also distributed according to the age at maturation. The model simulations qualitatively reproduce empirical trends, specifically the genotypic redistribution toward early-maturing types under increasing exploitation and the eventual collapse of the stock. Interestingly, increased effort targeted at large sizes seems to erode the genetic diversity, an effect missed by stochastic models that might serve as warning to fishery managers and policy makers. [ABSTRACT FROM AUTHOR]

Persistent organic pollutants like organochlorine pesticides continue to contaminate large areas worldwide raising questions concerning their management. We designed and tested a method to link soil and water pollution in the watershed of the Galion River in Martinique. We first estimated the risk of soil contamination by chlordecone by referring to past use of land for banana cultivation and took 27 soil samples. We then sampled surface waters at 39 points and groundwater at 16 points. We tested three hypotheses linked to the source of chlordecone pollution at the watershed scale: (i) soils close to the river, (ii) soils close to the sampling point, (iii) throughout the sub-watershed generated at the sampling point. Graphical and statistical analysis showed that contamination of the river increased when it passed through an area with contaminated plots and decreased when it passed through area not contaminated by chlordecone. Modeling showed that the entire surface area of the watershed contributed to river pollution, suggesting that the river was mainly being contaminated by the aquifers and groundwater flows. Our method proved to be a reliable way to identify areas polluted by chlordecone at the watershed scale and should help stakeholders focus their management actions on both hot spots and the whole watershed. [ABSTRACT FROM AUTHOR]

We propose a constructive method to design a pinning control law that synchronizes a network of stochastic dynamical systems. Different from traditional pinning control, we add to the standard proportional controller a nonlinear feedback term that, in the absence of coupling, would minimize a given cost functional. We then derive analytic guarantees that the proposed control law can effectively synchronize coupled noisy systems described by stochastic differential equations. Building on our theoretical results, we provide an algorithm for control design, whose effectiveness is illustrated on numerical testbeds. Finally, we perform extensive Monte Carlo simulations to evaluate the performance of the proposed nonlinear pinning strategy and compare it against the traditional proportional law. [ABSTRACT FROM AUTHOR]

To provide a full characterization of proper palmar digital arteries (PPDA) in systemic sclerosis (SSc) with ultra-high frequency ultrasound (UHFUS), and to investigate possible relationships between digital macroangiopathy and microangiopathy. SSc patients without active digital ulcers and healthy controls (HC) were enrolled. Each subject underwent UHFUS 70 MHz evaluation of PPDA from II to V fingers bilaterally, searching for vessel occlusion and measuring the thickness of the three arterial layers and the systolic-diastolic excursion range. Microcirculation was investigated with capillaroscopy and laser speckle contrast analysis (LASCA). Forty-six SSc patients (87% female, mean age 55.5 years) and 15 HC comparable for age and sex were enrolled. UHFUS in SSc revealed the occlusion of 124 (16.8%) PPDA, whereas in HC they were all patent. Considering a finger with at least one PPDA occluded as ultrasonographically pathological, 67.4% patients presented ≥1 pathological fingers. All three arterial layers were significantly thicker and excursion range significantly reduced in SSc than in HC (p<0.001 for all). Seventy-three percent of fingers previously affected by digital ulcers, were ultrasonographically pathological. Disease duration was directly correlated to the thickness of all three arterial layers. No significant correlations emerged between capillaroscopy or LASCA findings and UHFUS features. UHFUS allows the characterization of vasculopathic involvement of PPDA in SSc, also showing subclinical vasculopathy. The lack of correlations between UHFUS and capillaroscopy or LASCA likely mirrors non-overlapping vasculopathic processes. UHFUS evaluation of PPDA emerges as complementary to microcirculation assessment for a more accurate and complete characterization of SSc vasculopathy. [ABSTRACT FROM AUTHOR]

This paper investigates, in the context of discrete-time switched systems, the problem of comparison for path-complete stability certificates. We introduce and study abstract operations on path-complete graphs, called lifts , which allow us to recover previous results in a general framework. Moreover, this approach highlights the existing relations between the analytical properties of the chosen set of candidate Lyapunov functions (the template) and the admissibility of certain lifts. This provides a new methodology for the characterization of the ordering relation of path-complete Lyapunov functions criteria, when a particular template is chosen. We apply our results to specific templates, notably the sets of primal and dual copositive norms, providing new stability certificates for positive switched systems. These tools are finally illustrated with the aim of numerical examples. [ABSTRACT FROM AUTHOR]

Animal sociability measurements based on inter-individual distances or nearest-neighbour distributions can be obtained automatically with telemetry collars. So far, all the indices that have been used require the whole group to be observed. Here, we propose an index of the variability in affinity relationships in groups of domestic herbivores, whose definition does not depend on group size and that can be used even if some data are missing. This index and its estimators are based on a function that measures how frequently an animal is closer than another one from a third animal. When no data are missing, we show that our estimator and the variance of the sociability matrix sensu Sibbald (considered as the reference method) are strongly correlated. We then consider two cases of missing data. In the first case, some animals are randomly missing, that is, to account for random breakdown of telemetry collars. Our estimator is unbiased by such missing data and its variance decreases as the number of observation dates increases. In the second case, the same animals are missing at all observation dates, that is, in large herds where there are more individuals to be observed than available telemetry collars. Our estimator of affinity variance within a group is biased by such missing data. Thus, it requires changing animals equipped with telemetry collars regularly during the experiment. Conversely, the estimator remains unbiased at the population level, that is, if several independent groups are being analysed. We finally illustrate how this estimator can be used by investigating changes in the variability of affinities according to group size in grazing heifers. [ABSTRACT FROM PUBLISHER]

We propose a novel Lyapunov construction for continuous-time switched systems relying on a graph theoretical Lyapunov construction. Starting with a finite family of continuously differentiable functions, suitable inequalities involving these functions and the vector fields defining the switched system are encoded in a direct and labeled graph. We then provide sufficient conditions for (asymptotic) stability subject to constrained switching times, by relying on the path-completeness of the chosen graph. The analysis is first carried out under the hypothesis of constant switching frequency. Then, the results are generalized to dwell time setting. In the case of linear dynamics, the graph formalism allows us to interpret the existing results on dwell time stability in a unified language. Some numerical examples illustrate the usefulness of the conditions. [ABSTRACT FROM AUTHOR]

Abstract: Values are desirable, trans-situational goals, varying in importance, that guide behavior. Research has demonstrated that universal values may alter in importance as a result of major life events. The present study examines the effect of spaceflight and the demands of astronauts'' job position as life circumstances that affect value priorities. We employed thematic content analysis for references to Schwartz’s well-established value markers in narratives (media interviews, journals, and pre-flight interviews) of seven Canadian astronauts and compared the results to the values of National Aeronautics and Space Administration (NASA) and Russian Space Agency (RKA) astronauts. Space flight did alter the level of importance of Canadian astronauts’ values. We found a U-shaped pattern for the values of Achievement and Tradition before, during, and after flight, and a linear decrease in the value of Stimulation. The most frequently mentioned values were Achievement, Universalism, Security, and Self-Direction. Achievement and Self Direction are also within the top 4 values of all other astronauts; however, Universalism was significantly higher among the Canadian astronauts. Within the value hierarchy of Canadian astronauts, Security was the third most frequently mentioned value, while it is in seventh place for all other astronauts. Interestingly, the most often mentioned value marker (sub-category) in this category was Patriotism. The findings have important implications in understanding multi-national crew relations during training, flight, and reintegration into society. [Copyright &y& Elsevier]

Chronic environmental pollutions are one of the most striking examples of negative externalities of intensive agriculture. To address this issue, an agroecological transition is necessary, requiring new design methods: While most design methods are suited to the field or farm scale, some innovations require an approach at the scale of the territory. In this article, we propose a new method to design an agricultural territory aiming to overcome an environmental pollution issue, i.e. to identify one or more combinations of agricultural practices, implemented by the farmers of the territory that reduce water pollution. We implemented the new method following three steps: first, we used a sociotechnical diagnosis to identify cognitive biases that prevent the actors from innovating in a disruptive way. Second, we used the K C method (based on C K theory) to allow actors to innovate in a disruptive way. Third, we used a serious game to continue the design of the innovations and to test and assess them in a safe place. We implemented this new method in the Galion River watershed in Martinique (French West Indies) whose river is polluted by herbicides. Using the method, actors have overcome existing path dependencies. Based on this, the method made it possible to design different innovations across scales in a participative way and with a systemic territorial point of view. Here, actors designed 15 innovations that enhance either the territory or the pooling of its resources. Among these, there was the sharing of the service of an itinerant breeder or the implementation of an ecotouristic circuit. Actors combined innovations across scales into three scenarios that created a new agricultural territory with fewer agricultural herbicides in the river. We suggest adding two participatory steps to improve the level of genericity of the method: a first step to discuss the initial question and the general organisation of the participatory process, followed by a second step dealing with how to insert the designed innovations in the serious game. Finally, we recommend this method in other territories requiring collective practice changes. [Display omitted] • Solving herbicide pollution in river required new design methods to innovate at territory scale • We built a new method combining sociotechnical system, C-K design theory and serious game • Our method successfully created 15 innovations that can be combined on a tropical watershed to reduce herbicides in the river • The innovative design helped actors to create new solutions beyond agricultural sector and beyond the plot scale [ABSTRACT FROM AUTHOR]

Starting from a finite family of continuously differentiable positive definite functions, we study conditions under which a function obtained by max–min combinations is a Lyapunov function, establishing stability for two kinds of nonlinear dynamical systems: (a) Differential inclusions where the set-valued right-hand-side comprises the convex hull of a finite number of vector fields, and (b) Autonomous switched systems with a state-dependent switching signal. We investigate generalized notions of directional derivatives for these max–min functions, and use them in deriving stability conditions with various degrees of conservatism, where more conservative conditions are numerically more tractable. The proposed constructions also provide nonconvex Lyapunov functions, which are shown to be useful for systems with state-dependent switching that do not admit a convex Lyapunov function. Several examples are included to illustrate the results. [ABSTRACT FROM AUTHOR]

Herbicides used in agriculture pollute water worldwide. However, several weed management alternatives can reduce herbicide applications. The understanding of interactions between agronomics and the learning and social processes that favor changes in practices on a territorial scale is still far from complete. Despite the call for systemic change approaches, most studies are still based on technology transfer. Research and extension services provide references on alternative weed management practices and promote their use among farmers. We surveyed 33 farmers in a 45 km2 tropical catchment plus five institutional extension services. We analyzed changes in weed management practices on the 33 farms belonging to three different agricultural chains: local diversified horticulture, sugarcane, and export banana. For each change, we analyzed the learning processes and the networks involved in information exchanges. First, we show that the complexity of the practices promoted by extension services limits their adoption. Second, we show that simple practices adopted by farmers are part of a slow trajectory of change involving the gradual acquisition of knowledge. A redesign of cropping systems can emerge as the result of a gradual adding of complexity in practices and/or a specific systemic change on a cropping system scale. Sharing knowledge and resources in a non-competitive way speeds up changes among farmers sharing resources and promotes the redesigning of cropping systems. Third, we show that the structure and functioning of relational networks limit changes in practices on a watershed scale. We thus recommend that innovation design should incorporate co-designing of the pathway of change, by designing a succession of simple changes rather than a complex final system only. We recommend including non-competitive resource pooling among farmers in the co-designing of innovation. • We analyzed changes in weed management; learning processes and network influences. • Past changes and learning influenced actual weed management systems. • System redesign emerged from succession of simple changes or from systemic changes. • Pooling resources and knowledge in a non-competitive way stimulated system redesign. • Network structures affect opportunities for farmers to share resource and knowledge. [ABSTRACT FROM AUTHOR]