5,333 research outputs found

    Safe Drone Flight with Time-Varying Backup Controllers

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    The weight, space, and power limitations of small aerial vehicles often prevent the application of modern control techniques without significant model simplifications. Moreover, high-speed agile behavior, such as that exhibited in drone racing, make these simplified models too unreliable for safety-critical control. In this work, we introduce the concept of time-varying backup controllers (TBCs): user-specified maneuvers combined with backup controllers that generate reference trajectories which guarantee the safety of nonlinear systems. TBCs reduce conservatism when compared to traditional backup controllers and can be directly applied to multi-agent coordination to guarantee safety. Theoretically, we provide conditions under which TBCs strictly reduce conservatism, describe how to switch between several TBC's and show how to embed TBCs in a multi-agent setting. Experimentally, we verify that TBCs safely increase operational freedom when filtering a pilot's actions and demonstrate robustness and computational efficiency when applied to decentralized safety filtering of two quadrotors.Comment: Submitted to IROS 202

    Activation of waste tire char by cyclic liquid-phase oxidation

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    Activation of waste tire char was performed by successive cycles of liquid-phase oxidation followed by desorption in inert atmosphere at 650 °C. Significant differences in porosity development were found for the three oxidizing agents evaluated: nitric acid > hydrogen peroxide > ammonium persulfate. A linear increase of burn-off with the number of cycles was observed, reaching values between 63 and 90% after 15 activation cycles. Within the range tested, a higher concentration of the oxidizing agent (15 vs 30% v) led to higher burn-off, especially in the case of H2O2, however no differences were observed in terms of BET surface area (S BET) developed per unit of burn-off. SBET values around 750-400 m2/g were obtained by activation with HNO3 and H2O2, respectively. The activated carbons prepared by activation with HNO3 showed much higher mesopore volume (0.47-0.60 cm3/g) and some contribution of microporosity (0.03-15 cm 3/g). The mesopore size distribution in the samples activated with HNO3 (2-7 nm) was displaced to lower values than in the case of H2O2 (4-10 nm). The comparison with cyclic activation with air shows that liquid-phase oxidation provides higher porosity development, especially in the mesopore region but at the expense of higher burn-offThe authors greatly appreciate financial support from the Spanish Ministerio de Ciencia e Innovación (CTQ2009-09983) and the Ministerio de Economía y Competitividad (CTQ2012-32821

    Differential Immune-Reactivity and Subcellular Distribution Reveal the Multifunctional Character of Profilin in Pollen as Major Effect of Sequences Polymorphism

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    Trabajo presentado al Annual Meeting of the American Society of Agronomy and Crop Science Society and Soil Science Society of America, celebrado en Cincinnati (USA) del 21 al 24 de octubre de 2012.Profilin, one of the major allergen (Ole e 2) of olive (Olea europaea L.) pollen, are broadly distributed actin-monomer-binding proteins (ABP). They display a major regulatory role in actin cytoskeleton dynamics, driving cell morphogenesis, sexual reproduction, and translating signals into cellular responses to different environmental stresses. Plants exhibit multiple profilin isoforms w ith distinctive biochemical properties, and differentially regulated. How ever, it is still an open question w hether these profilin isoforms, generated by multiple gene sequence polymorphism, are functionally different, as well as the role of that polymorphism in pollen allergy. Particularly, in differential epitopes generation, profilin isoforms sensitization and cross-reactivity among cultivars, and even among species. In the present study, w e have used mature pollen from olive, birch, hazel, timothy-grass, and maize, in addition to olive germinating pollen and seeds, w ith the aim to analyze the immune-reactivity and subcellular localization of profilin by using polyclonal and specific isoforms antibodies against olive and maize profilins. The results show ed immune-reactivity differences betw een the five species analyzed, betw een olive cultivars, as w ell as between reproductive and vegetative profilins. Furthermore, the existence of different profilin isoforms w as revealed along pollen germination stages. A differential subcellular distribution of profilin isoforms w as found in olive pollen. They w ere localized in the nucleus, pollen aperture regions, pollen and tube w alls and pollen tip, in addition to a general cytoplasmic distribution, in comparison to controls. Data suggest that profilin family might contain numerous functionally distinctive isoforms, spatial-temporal differentially expressed and regulated during vegetative development, pollen maturation and pollen tube grow th. Furthermore, differential immune-reactivity revealed in the study might point out the involvement of common shared and specific epitopes, generated by sequence polymorphism, in differential olive pollen cultivar sensitization of allergenic patients, and cross-reaction to pollen from different species.This study was supported by the following European Regional Development Fund cofinanced grants: MCINN BFU 2004-00601/BFI, BFU 2008-00629, BFU2011-22779, CICE (Junta de Andalucía) P2010-CVI15767, P2010-AGR6274, P2011-CVI-7487, P2011-CVI-7487, and by the coordinated project Spain/Germany MEC HA2004-0094.Peer reviewe

    Basal Diet Determined Long-Term Composition of the Gut Microbiome and Mouse Phenotype to a Greater Extent than Fecal Microbiome Transfer from Lean or Obese Human Donors

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    The Western dietary pattern can alter the gut microbiome and cause obesity and metabolic disorders. To examine the interactions between diet, the microbiome, and obesity, we transplanted gut microbiota from lean or obese human donors into mice fed one of three diets for 22 weeks: (1) a control AIN93G diet; (2) the total Western diet (TWD), which mimics the American diet; or (3) a 45% high-fat diet-induced obesity (DIO) diet. We hypothesized that a fecal microbiome transfer (FMT) from obese donors would lead to an obese phenotype and aberrant glucose metabolism in recipient mice that would be exacerbated by consumption of the TWD or DIO diets. Prior to the FMT, the native microbiome was depleted using an established broad-spectrum antibiotic protocol. Interestingly, the human donor body type microbiome did not significantly affect final body weight or body composition in mice fed any of the experimental diets. Beta diversity analysis and linear discriminant analysis with effect size (LEfSe) showed that mice that received an FMT from obese donors had a significantly different microbiome compared to mice that received an FMT from lean donors. However, after 22 weeks, diet influenced the microbiome composition irrespective of donor body type, suggesting that diet is a key variable in the shaping of the gut microbiome after FMT

    Dietary Intervention with Black Raspberries to Reduce Colitis Symptoms in Mice Fed Either Standard AIN93G Diet or the Total Western Diet (P05-021-19)

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    Approximately 1.4 million people suffer from inflammatory bowel disease, which is a major risk factor for developing colitis associated colorectal cancer (CAC). Dietary interventions with the goal to reduce colon inflammation and encourage gut microbiome homeostasis may be a strategy to reduce the risk of CAC. The antioxidants and anti-inflammatory compounds present in black raspberries (BRB) have demonstrated protective effects in the colon epithelium and may alter the composition of the gut microbiome. Previously, we showed that dietary supplementation with black raspberries significantly suppressed colitis and colon tumorigenesis promoted by the consumption of a Western type diet in mice. The goal of this study was to compare the efficacy of dietary intervention with whole, freeze-dried black raspberries on colitis and colon tumorigenesis in mice consuming either a standard diet or a Western type diet that emulates typical U.S. nutrient intakes
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