This paper addresses the problem of leader–follower formation control in three dimensional space by exploring persistence of excitation (PE) of the desired formation. Using only bearing and relative ...velocity measurements, distributed control laws are derived for a group of agents with double-integrator dynamics. The key contribution is that the exponential stabilization of the actual formation to the desired one in terms of shape and scale is guaranteed as long as the PE conditions on the desired formation are satisfied. The approach generalizes stability results provided in prior work for leader–first follower (LFF) structures which are based on bearing rigidity and constraint consistence under a specific graph topology to ensure the exponential stabilization of the actual formation to a desired static geometric pattern up to a scale factor. Simulations results are provided to illustrate the performance of the proposed control method.
Neutrophils are polymorphonuclear leukocytes of the phagocytic system that act as first line of host defense against invading pathogens but are also important mediators of inflammation-induced ...injury. In contrast to other members of the innate immune system, neutrophils are classically considered a homogenous population of terminally differentiated cells with a well-defined and highly conserved function. Indeed, their short lifespan, the absent proliferative capacity, their limited ability to produce large amounts of cytokines, and the failure to recirculate from the tissue to the bloodstream have sustained this idea. However, increasing evidence over the last decade has demonstrated an unexpected phenotypic heterogeneity and functional versatility of the neutrophil population. Far beyond their antimicrobial functions, neutrophils are emerging as decision-shapers during innate and adaptive immune responses. These emerging discoveries open a new door to understand the role of neutrophils during homeostatic but also pathogenic immune processes. Thus, this review details novel insights of neutrophil phenotypic and functional heterogeneity during homeostasis and disease.
This paper addresses the design and experimental evaluation of a robust controller for a quadrotor landing maneuver comprising the approach to a landing slope and sliding on that slope, before coming ...to a complete halt. During the critical landing flight phase, the dynamics of the vehicle change with the type of contact with the ground, and a hybrid automaton, whose states reflect the several dynamic behaviors of the quadrotor, is employed to model the vehicle throughout the complete maneuver. The quadrotor landing problem is broken down as separate maneuver generation and robust trajectory tracking problems, which are combined to achieve a successful maneuver that is robust to possible uncertainties. The experimental results are provided to attest to the feasibility of the proposed landing procedure.
Abstract
At the frontline of the host defence response, neutrophil antimicrobial functions have adapted to combat infections and injuries of different origins and magnitude. The release of web-like ...DNA structures named neutrophil extracellular traps (NETs) constitutes an important mechanism by which neutrophils prevent pathogen dissemination or deal with microorganisms of a bigger size. At the same time, nuclear and granule proteins with microbicidal activity bind to these DNA structures promoting the elimination of entrapped pathogens. However, these toxic properties may produce unwanted effects in the host, when neutrophils uncontrollably release NETs upon persistent inflammation. As a consequence, NET accumulation can produce vessel occlusion, tissue damage, and prolonged inflammation associated with the progression and exacerbation of multiple pathologic conditions. This review outlines recent advances in understanding the mechanisms of NET release and functions in sterile disease. We also discuss mechanisms of physiological regulation and the importance of neutrophil heterogeneity in NET formation and composition.
We address the problem of a set of agents reaching consensus by computing the average of their initial states. We propose two randomized algorithms over a directed communication graph where either a ...random node broadcast its value or a randomly selected pair of nodes communicate in a distributed fashion. The proposed algorithms guarantee convergence in three important definitions, namely: almost surely, in expectation, and in the mean-square sense. We show how the parameters of the algorithm can be optimized to improve the rate of convergence and compare its rates of convergence for directed and undirected graphs.
This paper presents the steps for developing a low-cost POrtableNavigation Tool for Underwater Scenarios (PONTUS) to be used as a localization device for subsea targets. PONTUS consists of an ...integrated ultra-short baseline acoustic positioning system aided by an inertial navigation system. Built on a practical design, it can be mounted on an underwater robotic vehicle or be operated by a scuba diver. It also features a graphical user interface that provides information on the tracking of the designated target, in addition to some details on the physical properties inside PONTUS. A full disclosure of the architecture of the tool is first presented, followed by thorough technical descriptions of the hardware components ensemble and the software development process. A series of experiments was carried out to validate the developed prototype, and the results are presented herein, which allow assessing its overall performance.
Atheroprogression is a consequence of nonresolved inflammation, and currently a comprehensive overview of the mechanisms preventing resolution is missing. However, in acute inflammation, resolution ...is known to be orchestrated by a switch from inflammatory to resolving lipid mediators. Therefore, we hypothesized that lesional lipid mediator imbalance favors atheroprogression.
To understand the lipid mediator balance during atheroprogression and to establish an interventional strategy based on the delivery of resolving lipid mediators.
Aortic lipid mediator profiling of aortas from Apoe
mice fed a high-fat diet for 4 weeks, 8 weeks, or 4 months revealed an expansion of inflammatory lipid mediators, Leukotriene B4 and Prostaglandin E2, and a concomitant decrease of resolving lipid mediators, Resolvin D2 (RvD2) and Maresin 1 (MaR1), during advanced atherosclerosis. Functionally, aortic Leukotriene B4 and Prostaglandin E2 levels correlated with traits of plaque instability, whereas RvD2 and MaR1 levels correlated with the signs of plaque stability. In a therapeutic context, repetitive RvD2 and MaR1 delivery prevented atheroprogression as characterized by halted expansion of the necrotic core and accumulation of macrophages along with increased fibrous cap thickness and smooth muscle cell numbers. Mechanistically, RvD2 and MaR1 induced a shift in macrophage profile toward a reparative phenotype, which secondarily stimulated collagen synthesis in smooth muscle cells.
We present evidence for the imbalance between inflammatory and resolving lipid mediators during atheroprogression. Delivery of RvD2 and MaR1 successfully prevented atheroprogression, suggesting that resolving lipid mediators potentially represent an innovative strategy to resolve arterial inflammation.
This paper addresses the problem of nonlinear height tracking control of an automobile active air suspension with the output state constraints and time-varying disturbances. The proposed control ...strategy guarantees that the ride height stays within a predefined range, and converges closely to an arbitrarily small neighborhood of the desired height, ensuring uniform ultimate boundedness. The designed nonlinear observer is able to compensate for the time-varying disturbances caused by external random road excitation and perturbations, achieving robust performance. Simulation results obtained from the co-simulation (AMESim-Matlab/Simulink) are given and analyzed, demonstrating the efficiency of the proposed control methodology.
Obesity-associated diseases such as Type 2 diabetes, liver disease and cardiovascular diseases are profoundly mediated by low-grade chronic inflammation of the adipose tissue. Recently, the ...importance of neutrophils and neutrophil-derived myeloperoxidase and neutrophil elastase on the induction of insulin resistance has been established. Since neutrophil elastase and myeloperoxidase are critically involved in the release of neutrophil extracellular traps (NETs), we here hypothesized that NETs may be relevant to early adipose tissue inflammation. Thus, we tested the effect of the Peptidyl Arginine Deiminase 4 inhibitor Cl-amidine, a compound preventing histone citrullination and subsequent NET release, in a mouse model of adipose tissue inflammation. C57BL6 mice received a 60% high fat diet for 10 weeks and were treated with either Cl-amidine or vehicle. Flow cytometry of adipose tissue and liver, immunohistological analysis and glucose and insulin tolerance tests were performed to determine the effect of the treatment and diet. Although high fat diet feeding induced insulin resistance no significant effect was observed between the treatment groups. In addition no effect was found in leukocyte infiltration and activation in the adipose tissue and liver. Therefore we concluded that inhibition of neutrophil extracellular trap formation may have no clinical relevance for early obesity-mediated pathogenesis of the adipose tissue and liver.
Onset of cardiovascular complications as a consequence of atherosclerosis exhibits a circadian incidence with a peak in the morning hours. Although development of atherosclerosis extends for long ...periods of time through arterial leukocyte recruitment, we hypothesized that discrete diurnal invasion of the arterial wall could sustain atherogenic growth. Here, we show that myeloid cell recruitment to atherosclerotic lesions oscillates with a peak during the transition from the activity to the resting phase. This diurnal phenotype is regulated by rhythmic release of myeloid cell-derived CCL2, and blockade of its signaling abolished oscillatory leukocyte adhesion. In contrast, we show that myeloid cell adhesion to microvascular beds peaks during the early activity phase. Consequently, timed pharmacological CCR2 neutralization during the activity phase caused inhibition of atherosclerosis without disturbing microvascular recruitment. These findings demonstrate that chronic inflammation of large vessels feeds on rhythmic myeloid cell recruitment, and lay the foundation for chrono-pharmacology-based therapy.
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•Myeloid cells adhere to atherosclerotic lesions in a circadian fashion•Circulating myeloid cells deposit CCL2 rhythmically on the arterial endothelium•Myeloid cell adhesion patterns in macro- and microcirculation are 12 hr phase shifted•Chrono-pharmacological treatment strategy targets early atherosclerosis development
Winter et al. identify an oscillatory myeloid cell recruitment pattern to atherosclerotic lesions regulated, in part, by rhythmic deposition of CCL2 on arterial endothelium. These findings lay the foundation for a chrono-pharmacological treatment strategy targeting early lesion development without disturbing microvascular recruitment of myeloid cells.
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