Plant-associated microbes are important for the growth and health of their hosts. As a result of numerous prior studies, we know that host genotypes and abiotic factors influence the composition of ...plant microbiomes. However, the high complexity of these communities challenges detailed studies to define experimentally the mechanisms underlying the dynamics of community assembly and the beneficial effects of such microbiomes on plant hosts. In this work, from the distinctive microbiota assembled by maize roots, through host-mediated selection, we obtained a greatly simplified synthetic bacterial community consisting of seven strains (Enterobacter cloacae, Stenotrophomonas maltophilia, Ochrobactrum pituitosum, Herbaspirillum frisingense, Pseudomonas putida, Curtobacterium pusillum, and Chryseobacterium indologenes) representing three of the four most dominant phyla found in maize roots. By using a selective culture-dependent method to track the abundance of each strain, we investigated the role that each plays in community assembly on roots of axenic maize seedlings. Only the removal of E. cloacae led to the complete loss of the community, and C. pusillum took over. This result suggests that E. cloacae plays the role of keystone species in this model ecosystem. In planta and in vitro, this model community inhibited the phytopathogenic fungus Fusarium verticillioides, indicating a clear benefit to the host. Thus, combined with the selective culture-dependent quantification method, our synthetic seven-species community representing the root microbiome has the potential to serve as a useful system to explore how bacterial interspecies interactions affect root microbiome assembly and to dissect the beneficial effects of the root microbiota on hosts under laboratory conditions in the future.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
In this technical note, the problem of switching stabilization for slowly switched linear systems is investigated. In particular, the considered systems can be composed of all unstable subsystems. ...Based on the invariant subspace theory, the switching signal with mode-dependent average dwell time (MDADT) property is designed to exponentially stabilize the underlying system. Furthermore, sufficient condition of stabilization for switched systems with all stable subsystems under MDADT switching is also given. The correctness and effectiveness of the proposed approaches are illustrated by a numerical example.
The present study evaluated the effect of dietary sodium butyrate (NaBT) supplementation on the growth performance, intestinal microbiota composition, and liver health of largemouth bass Micropterus ...salmoides fed high-fat diets. Four isonitrogenous and isolipid diets were formulated: a high-fat diet and the high-fat diet supplemented by 0.05% NaBT, 0.1% NaBT, or 0.2% NaBT. Each diet was randomly distributed to triplicate tanks (200L) containing 30 fish (initial weight 4.0 ± 0.1 g) per tank. The experimental fish were fed to apparent satiation twice daily for 60 days. The orthogonal polynomial contrasts showed that the weight gain rate (WGR) and specific growth rate (SGR) increased linearly (P < 0.05) with increasing dietary NaBT levels (P < 0.05). No significant differences were found for feed intake (FI), feed conversion ratio (FCR), condition factor (CF), viscerosomatic index (VSI), and hepatosomatic index (HSI). There were no differences in the alpha diversity indices (including Operational Taxonomic Units, Chao index, and Simpson index) of intestinal microbiota between the various dietary groups (P > 0.05). For the intestinal microbiota composition, the proportion of Proteobacteria were linearly and cubically increased, whereas the proportion of Tenericutes and Mesomycoplasma were linearly and cubically decreased with the increase of dietary NaBT levels (P < 0.05). The increasing dietary NaBT levels led to significantly quadratic decrease of alanine aminotransferase (ALT) (P < 0.05), linear and quadratic decrease of aspartate aminotransferase (AST) (P < 0.05), and linear, quadratic, and cubic decrease of diamine oxidase (DAO) (P < 0.05). Hepatic triglyceride (TG) and total cholesterol (TCHO) contents decreased linearly and quadratically with the increase of dietary NaBT levels (P < 0.05). Increasing dietary NaBT levels linearly, quadratically, and cubically decreased the malondialdehyde (MDA) contents (P < 0.05). Total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) activity levels increased linearly with the increasing dietary NaBT levels (P < 0.05). As the dietary NaBT levels gradually increased, the relative expression of carnitine palmitoyl transferase (CPT1) and peroxisome proliferator-activated receptor α (PPARα) increased linearly, quadratically, and cubically (P < 0.05), while the relative expression of sterol regulatory element binding protein 1 (SREBP 1) decreased linearly, quadratically, and cubically (P < 0.05). The relative expression of tumor necrosis factor α (TNF-α) and cysteinyl aspartate specific protease 3 (Caspase 3) decreased linearly and quadratically with the increasing NaBT levels (P < 0.05). Pearson correlation analysis showed that fish growth was closely correlated with microbiota composition, hepatic lipid accumulation, hepatic antioxidant-related parameters, and hepatic gene expression (P < 0.05). These results indicated that NaBT could be used to alleviate the negative influence of high-fat diets on fish growth, intestinal microbiota homeostasis, and liver health.
•Growth of Micropterus salmoides fed high-fat diets was improved by sodium butyrate.•NaBT alleviates the high-fat diet-induced liver injury and gut microbiota dysbiosis.•The gut microbiota and PPARα play key roles in the beneficial effects of NaBT.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, the problem of switching stabilization for a class of switched nonlinear systems is studied by using average dwell time (ADT) switching, where the subsystems are possibly all unstable. ...First, a new concept of ADT is given, which is different from the traditional definition of ADT. Based on the new proposed switching signals, a sufficient condition of stabilization for switched nonlinear systems with unstable subsystems is derived. Then, the T-S fuzzy modeling approach is applied to represent the underlying nonlinear system to make the obtained condition easily verified. A novel multiple quadratic Lyapunov function approach is also proposed, by which some conditions are provided in terms of a set of linear matrix inequalities to guarantee the derived T-S fuzzy system to be asymptotically stable. Finally, a numerical example is given to demonstrate the effectiveness of our developed results.
This article focuses on the tracking control problem for switched nonlinear systems in strict-feedback form subject to an output constraint. In order to prevent transgression of the constraint, a ...barrier Lyapunov function is employed, which grows to infinity when its arguments approach domain boundaries. Under the simultaneous domination assumption, a continuous controller for the switched system is constructed. Furthermore, asymptotic tracking is achieved without violation of the constraint, and all closed-loop signals keep bounded, when a mild requirement on the initial condition is satisfied. Finally, a simulation example is provided to illustrate the effectiveness of the proposed results.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
In this paper, a new adaptive approximation-based tracking controller design approach is developed for a class of uncertain nonlinear switched lower-triangular systems with an output constraint using ...neural networks (NNs). By introducing a novel barrier Lyapunov function (BLF), the constrained switched system is first transformed into a new system without any constraint, which means the control objectives of the both systems are equivalent. Then command filter technique is applied to solve the so-called "explosion of complexity" problem in traditional backstepping procedure, and radial basis function NNs are directly employed to model the unknown nonlinear functions. The designed controller ensures that all the closed-loop variables are ultimately boundedness, while the output limit is not transgressed and the output tracking error can be reduced arbitrarily small. Furthermore, the use of an asymmetric BLF is also explored to handle the case of asymmetric output constraint as a generalization result. Finally, the control performance of the presented control schemes is illustrated via two examples.
Carbon taxes increase costs for energy-consuming firms and can impact firms‘ ability to compete with other firms located in regions without that tax. This paper considers the effect of asymmetric ...carbon taxation when firms are able to adjust their energy efficiency investment levels to reflect the presence of the tax. Using a dynamic model of firm competition, we find that allowing firms to adjust their energy efficiency levels in response to a carbon tax could potentially allow firms to significantly mitigate the competition effects of that carbon tax. In our baseline parameterization, additional energy efficiency investments non-trivially mitigates profit loss for the firm facing the carbon tax as well as spurring adding energy efficiency investments in the non-taxing jurisdiction, thus reducing carbon leakage. This increase in energy efficiency can potentially reduce total energy usage by the firm in the taxing jurisdiction by more than the carbon tax alone. While the quantitative impact of energy efficiency investments on firm competitiveness depends on the nature of the industry, from a policy standpoint, the ability of energy efficiency investments to mitigate cross-border emissions leakage and negative competition effects without policy interventions such as a carbon border tax softens these two common criticisms of unilateral regional carbon taxes.
•Regional carbon taxes can impact firms' ability to compete with untaxed firms.•Improving firm energy efficiency can mitigate some of these negative effects.•Improving firm energy efficiency can also reduce carbon leakage.•These effects can soften common criticisms of a regional carbon tax.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper considers the problem of adaptive fuzzy backstepping-based output-feedback controller design for a class of uncertain switched nonlinear stochastic systems in lower-triangular form without ...the measurements of the system states. By combining fuzzy logic systems' universal approximation ability and dynamic surface control technique in the adaptive backstepping recursive design with a modified average dwell-time scheme, a new adaptive fuzzy control approach is presented for the switched system. More specifically, a switched observer is constructed to reduce the conservativeness aroused by the employ of a common observer, and individual coordinate transformations for subsystems are given up by adopting a common coordinate transformation of all subsystems. It is proved that the overall closed-loop system is stable in the sense of semi-globally uniformly ultimately bounded in mean square, and the output of the switched system converges to a small neighborhood of the origin with appropriate choice of design parameters. Finally, simulation studies are provided to demonstrate the validity of the proposed control method.
When mining in high dimensional data, the curse of dimensionality is one of the major difficulty to overcome. In this paper, a weighted feature selection strategy is developed and embedded in ...bacterial based algorithms to reduce the feature dimension in classification. The proposed weighted feature selection strategy distinguishes the features by their classification performances as well as the occurrence frequency in population according to the two matrices. The objectives of minimizing the number of features, maximizing the performance, and minimizing the computational cost are all considered. Regarding the drawback of bacterial based algorithms, Bacterial Colony Optimization based feature selection algorithm is proposed to decrease the computational complexity as well as improve the search ability even in discrete optimization problems. To test the effectiveness of the proposed feature selection method, four bacterial based methods with the weighted strategy embedded have been compared with four classical feature selection methods and three well-known population based algorithms using 15 cancer micro-array datasets with different numbers of features and classes. The results show that the weighted feature selection strategies embedded have improved the feature selection capability of bacterial algorithms. The new proposed mechanisms embedded in Bacterial Colony Optimization method can overcome the limitation of the traditional bacterial based algorithms using premature termination to decrease the computational time, and provide comparable or in most cases better solutions than other feature selection methods considered in the comparison.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Mesoporous materials are materials with high surface area and intrinsic porosity, and therefore have attracted great research interest due to these unique structures. Mesoporous titanium dioxide ...(TiO₂) is one of the most widely studied mesoporous materials given its special characters and enormous applications. In this article, we highlight the significant work on mesoporous TiO₂ including syntheses and applications, particularly in the field of photocatalysis, energy and biology. Different synthesis methods of mesoporous TiO₂-including sol⁻gel, hydrothermal, solvothermal method, and other template methods-are covered and compared. The applications in photocatalysis, new energy batteries and in biological fields are demonstrated. New research directions and significant challenges of mesoporous TiO₂ are also discussed.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
PDF
