For input delayed systems, the sequential subpredictor (SSP) control scheme has the advantage that arbitrarily large delays can be tolerated in the control loop by introducing more and more ...subpredictors. However, an exact delay compensation is not possible in the presence of time-varying delay mismatches, and larger delays cannot therefore be obtained by increasing the number of subpredictors. To alleviate this limitation and enhance robustness against time-varying delay uncertainties, a generalized sequential subpredictor (SSP) control scheme is proposed by introducing new observer parameters that can be designed via Linear Matrix Inequalities (LMI) and Cone-Complementarity Linearization (CCL) algorithm. Finally, the effectiveness of the proposed method is illustrated by a simulation example.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A novel distributed predictor-feedback control scheme is presented.•We have introduced a weighting factor in the prediction scheme.•Event-triggered control is combined with weighting prediction ...scheme.•The proposed method outperforms other approaches for interconnected systems with delays.•A CCL algorithm is provided to design the controller parameters.
The paper investigates the control design of interconnected time delay systems by means of distributed predictor-feedback delay compensation approaches and event-triggered mechanism. The idea behind delay compensation is to counteract the negative effects of delays in the control-loop by feeding back future predictions of the system state. Nevertheless, an exact prediction of the overall system state vector cannot be obtained providing that each system has only knowledge of their local data regarding the system model and state variables. Consequently, predictor-feedback delay compensation may lose effectiveness if the coupling between subsystems is sufficiently strong. To circumvent this drawback, the proposed distributed predictor-feedback control incorporates extra degree of freedom for control synthesis by introducing new weighting factors for each local prediction term. The design of the weighting factors is addressed, together with the event-triggered parameters, by an algorithm based on Linear Matrix Inequalities (LMI) and the Cone Complementarity Linearization (CCL). Simulation results are provided to show the achieved improvements and validate the effectiveness of the proposed method, even in the case that other control strategies fail to stabilize the closed-loop system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper proposes novel conditions based on linear matrix inequalities (LMI) for stability analysis of arbitrarily-fast time-varying delays systems. The time-varying delay interval is divided into ...smaller pieces in order to obtain an equivalent switched model with multiple time-varying delays of smaller interval, which differently from other existing approaches, the maximum switching frequency is not required for stability analysis. Thus, by the use of augmented Lyapunov-Krasovskii functionals and the Finsler’s lemma, together with some relationships among state variables intentionally defined, the inherent conservatism can be progressively reduced by refining more and more the delay partition. The superiority of the proposed method is illustrated through two benchmark examples.
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Oaks (Quercus, Fagaceae) are the dominant tree genus of North America in species number and biomass, and Mexico is a global center of oak diversity. Understanding the origins of oak diversity is key ...to understanding biodiversity of northern temperate forests.
A phylogenetic study of biogeography, niche evolution and diversification patterns in Quercus was performed using 300 samples, 146 species. Next-generation sequencing data were generated using the restriction-site associated DNA (RAD-seq) method. A time-calibrated maximum likelihood phylogeny was inferred and analyzed with bioclimatic, soils, and leaf habit data to reconstruct the biogeographic and evolutionary history of the American oaks.
Our highly resolved phylogeny demonstrates sympatric parallel diversification in climatic niche, leaf habit, and diversification rates. The two major American oak clades arose in what is now the boreal zone and radiated, in parallel, from eastern North America into Mexico and Central America.
Oaks adapted rapidly to niche transitions. The Mexican oaks are particularly numerous, not because Mexico is a center of origin, but because of high rates of lineage diversification associated with high rates of evolution along moisture gradients and between the evergreen and deciduous leaf habits. Sympatric parallel diversification in the oaks has shaped the diversity of North American forests.
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This paper investigates the exponential stability of uncertain time delay systems using a novel descriptor redundancy approach based on delay partitioning. First, the original system is casted into ...an equivalent descriptor singular state-space representation by introducing redundant state variables so that the resulting delay is progressively reduced. From the equivalent model and applying Lyapunov Functional method, a sufficient condition based on Linear Matrix Inequalities (LMIs) for exponential stability with guaranteed decay rate performance is obtained. As a result, the inherent conservatism of Lyapunov-Krasovskii functional techniques can arbitrarily be reduced by increasing the number of delay partition intervals including decay rate performance and model uncertainties in polytopic form. Various benchmark examples are provided to validate the effectiveness of the proposed method, showing better trade-off between conservatism and performance in comparison to previous approaches.
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The lateral hypothalamus (LH) controls energy balance. LH melanin-concentrating-hormone (MCH) and orexin/hypocretin (OH) neurons mediate energy accumulation and expenditure, respectively. MCH cells ...promote memory and appropriate stimulus-reward associations; their inactivation disrupts energy-optimal behaviour and causes weight loss. However, MCH cell dynamics during wakefulness are unknown, leaving it unclear if they differentially participate in brain activity during sensory processing. By fiberoptic recordings from molecularly defined populations of LH neurons in awake freely moving mice, we show that MCH neurons generate conditional population bursts. This MCH cell activity correlates with novelty exploration, is inhibited by stress and is inversely predicted by OH cell activity. Furthermore, we obtain brain-wide maps of monosynaptic inputs to MCH and OH cells, and demonstrate optogenetically that VGAT neurons in the amygdala and bed nucleus of stria terminalis inhibit MCH cells. These data reveal cell-type-specific LH dynamics during sensory integration, and identify direct neural controllers of MCH neurons.
Urolithins, metabolites produced by the gut microbiota from the polyphenols ellagitannins and ellagic acid, are discovered by the research group in humans almost 20 years ago. Pioneering research ...suggests urolithins as pleiotropic bioactive contributors to explain the health benefits after consuming ellagitannin‐rich sources (pomegranates, walnuts, strawberries, etc.). Here, this study comprehensively updates the knowledge on urolithins, emphasizing the review of the literature published during the last 5 years. To date, 13 urolithins and their corresponding conjugated metabolites (glucuronides, sulfates, etc.) have been described and, depending on the urolithin, detected in different human fluids and tissues (urine, blood, feces, breastmilk, prostate, colon, and breast tissues). There has been a substantial advance in the research on microorganisms involved in urolithin production, along with the compositional and functional characterization of the gut microbiota associated with urolithins metabolism that gives rise to the so‐called urolithin metabotypes (UM‐A, UM‐B, and UM‐0), relevant in human health. The design of in vitro studies using physiologically relevant assay conditions (molecular forms and concentrations) is still a pending subject, making some reported urolithin activities questionable. In contrast, remarkable progress has been made in the research on the safety, bioactivity, and associated mechanisms of urolithin A, including the first human interventions.
About 20 years ago, urolithins are discovered as bioavailable metabolites produced by the human gut microbiota from ellagitannins and ellagic acid. Pioneering investigations suggested pleiotropic effects for urolithins that growing evidence confirms, especially for urolithin A. Here, we update the knowledge on urolithins metabolism, bioactivity, and associated gut microbiota, emphasizing the literature published in the last 5 years.
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The full consensus on the role of dietary polyphenols as human‐health‐promoting compounds remains elusive. The two‐way interaction between polyphenols and gut microbiota (GM) (i.e., modulation of GM ...by polyphenols and their catabolism by the GM) is determinant in polyphenols’ effects. The identification of human metabotypes associated with a differential gut microbial metabolism of polyphenols has opened new research scenarios to explain the inter‐individual variability upon polyphenols consumption. The metabotypes unequivocally identified so far are those involved in the metabolism of isoflavones (equol and(or) O‐desmethylangolesin producers versus non‐producers) and ellagic acid (urolithin metabotypes, including producers of only urolithin‐A (UM‐A), producers of urolithin‐A, isourolithin‐A, and urolithin‐B (UM‐B), and non‐producers (UM‐0)). In addition, the microbial metabolites (phenolic‐derived postbiotics) such as equol, urolithins, valerolactones, enterolactone, and enterodiol, and 8‐prenylnaringenin, among others, can exert differential health effects. The knowledge is updated and position is taken here on i) the two‐way interaction between GM and polyphenols, ii) the evidence between phenolic‐derived postbiotics and health, iii) the role of metabotypes as biomarkers of GM and the clustering of individuals depending on their metabotypes (metabotyping) to explain polyphenols’ effects, and iv) the gut microbial metabolism of catecholamines to illustrate the intersection between personalized nutrition and precision medicine.
Human metabotypes (HMs) are at the crossroads of polyphenols' (PPs) health effects. HMs, associated with a differential gut microbial metabolism of PPs, have opened new scenarios to explain the inter‐individual variability upon PPs intake. The two‐way interaction between gut microbiota (GM) and PPs, the phenolic postbiotics, the metabotyping, and HMs as biomarkers of GM participate in this complex cocktail.
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Deeply stratified settlements are a distinctive site type featuring prominently in diverse later prehistoric landscapes of the Old World. Their massive materiality has attracted the curiosity of lay ...people and archaeologists alike. Nowadays a wide variety of archaeological projects are tracking the lifestyles and social practices that led to the building-up of such superimposed artificial hills. However, prehistoric tell-dwelling communities are too often approached from narrow local perspectives or discussed within strict time- and culture-specific debates. There is a great potential to learn from such ubiquitous archaeological manifestations as the physical outcome of cross-cutting dynamics and comparable underlying forces irrespective of time and space.This volume tackles tells and tell-like sites as a transversal phenomenon whose commonalities and divergences are poorly understood yet may benefit from cross-cultural comparison. Thus, the book intends to assemble a representative range of ongoing theory - and science -based fieldwork projects targeting this kind of sites. With the aim of encompassing a variety of social and material dynamics, the volume's scope is diachronic - from the Earliest Neolithic up to the Iron Age-, and covers a very large region, from Iberia in Western Europe to Syria in the Middle East. The core of the volume comprises a selection of the most remarkable contributions to the session with a similar title celebrated in the European Association of Archaeologists Annual Meeting held at Barcelona in 2018. In addition, the book includes invited chapters to round out underrepresented areas and periods in the EAA session with relevant research programmes in the Old World. To accomplish such a cross-cultural course, the book takes a case-based approach, with contributions disparate both in their theoretical foundations - from household archaeology, social agency and formation theory - and their research strategies - including geophysical survey, microarchaeology and high-resolution excavation and dating.
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(Poly)phenols (PPs) constitute a large family of phytochemicals with high chemical diversity that are known to be active principles of plant-derived nutraceuticals and herbal ...medicinal products. Their pharmacological activity, however, is difficult to demonstrate due to their mild physiological effects, and to the large inter-individual variability observed. Many PPs have little bioavailability and reach the colon almost unaltered. There they encounter the gut microbes resulting in a two-way interaction in which PPs modulate the gut microbiota composition, and the intestinal microbes catabolize the ingested PPs to release metabolites that are often more active and better absorbed than the native phenolic compounds. The type and quantity of the PP metabolites produced in humans depend on the gut microbiota composition and function, and different metabotypes have been identified. However, not all the metabolites have the same biological activity, and therefore the final health effects of dietary PPs depend on the gut microbiota composition. Stratification in clinical trials according to individuals’ metabotypes is necessary to fully understand the health effects of PPs. In this review, we present and discuss the most significant and updated knowledge regarding the reciprocal interrelation of the gut microbiota with dietary PPs as a key factor that modulates the health effects of these compounds. The review will focus in those PPs that are known to be metabolized by gut microbiota resulting in bioactive metabolites.
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