This paper studies a leader-following rendezvous problem for a double integrator multi-agent system where the leader system can generate a class of signals such as ramp signal and sinusoidal signals ...with arbitrary amplitudes and initial phases. Motivated by some techniques in output regulation theory, we propose a dynamic distributed state feedback control protocol that is able to maintain the connectivity of an initially connected communication network, and, at the same time, achieve the objective of the asymptotic tracking of all followers to the leader regardless of external disturbances.
The cooperative output regulation problem for singular multi-agent systems subject to static networks was studied recently under the assumption that each follower system satisfies the standard ...assumption. In this paper, we further study the same problem for singular multi-agent systems subject to jointly connected switching networks. First, by introducing a static output feedback control, we remove the unnecessary standard assumption on the singular system in the existing result. Then, we derive a reduced-order normal multi-agent system and obtain a distributed output measurement feedback control law based on the existing result on the normal multi-agent system. Finally, we show that the composition of the static output feedback control law and the distributed output measurement feedback control law solves the cooperative output regulation problem for the original singular multi-agent system. Our result enlarges the class of systems whose cooperative output regulation problem is solvable.
Multiple-input-multiple-output (MIMO) techniques have been actively pursued recently in underwater acoustic communications to increase the data rate over the bandwidth-limited channels. In this ...communication, we present a MIMO system design, where spatial multiplexing is applied with orthogonal-frequency-division-multiplexing (OFDM) signals. The proposed receiver works on a block-by-block basis, where null subcarriers are used for Doppler compensation, pilot subcarriers are used for channel estimation, and a MIMO detector consisting of a hybrid use of successive interference cancellation and soft minimum mean square error (MMSE) equalization is coupled with low-density parity-check (LDPC) channel decoding for iterative detection on each subcarrier. The proposed design has been tested using data recorded from three different experiments. A spectral efficiency of 3.5 b/s/Hz was approached in one experiment, while a data rate of 125.7 kb/s over a bandwidth of 62.5 kHz was achieved in another. These results suggest that MIMO-OFDM is an appealing solution for high-data-rate transmissions over underwater acoustic channels.
Two benzoylpyridine-carbazole based fluorescence materials DCBPy and DTCBPy, bearing two carbazolyl and 4-(t-butyl)carbazolyl groups, respectively, at the meta and ortho carbons of the benzoyl ring, ...were synthesized. These molecules show very small ΔE ST of 0.03 and 0.04 eV and transient PL characteristics indicating that they are thermally activated delayed fluorescence (TADF) materials. In addition, they show extremely different photoluminescent quantum yields in solution and in the solid state: in cyclohexane the value are 14 and 36%, but in the thin films, the value increase to 88.0 and 91.4%, respectively. The OLEDs using DCBPy and DTCBPy as dopants emit blue and green light with EQEs of 24.0 and 27.2%, respectively, and with low efficiency roll-off at practical brightness level. The crystal structure of DTCBPy reveals a substantial interaction between the ortho donor (carbazolyl) and acceptor (4-pyridylcarbonyl) unit. This interaction between donor and acceptor substituents likely play a key role to achieve very small ΔE ST with high photoluminescence quantum yield.
Tumor vasculature abnormality creates a microenvironment that is not suitable for anti-tumor immune response and thereby induces resistance to immunotherapy. Remodeling of dysfunctional tumor blood ...vessels by anti-angiogenic approaches, known as vascular normalization, reshapes the tumor microenvironment toward an immune-favorable one and improves the effectiveness of immunotherapy. The tumor vasculature serves as a potential pharmacological target with the capacity of promoting an anti-tumor immune response. In this review, the molecular mechanisms involved in tumor vascular microenvironment-modulated immune reactions are summarized. In addition, the evidence of pre-clinical and clinical studies for the combined targeting of pro-angiogenic signaling and immune checkpoint molecules with therapeutic potential are highlighted. The heterogeneity of endothelial cells in tumors that regulate tissue-specific immune responses is also discussed. The crosstalk between tumor endothelial cells and immune cells in individual tissues is postulated to have a unique molecular signature and may be considered as a potential target for the development of new immunotherapeutic approaches.
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•Microbial networks were distinctly different among seasons.•Networks with higher complexity and more keystone taxa exhibited higher stability.•Water temperature and pH influenced ...microbial networks and community stability.•Keystone taxa could be regarded as the indicators of community stability.
Seasonal variations of environmental factors generally result in considerable changes in microbiomes, yet we still lack a clear understanding of how microbial communities maintain their ecological stability. Here, we analyze a long-term (nine years) high-throughput sequencing dataset by network analysis to illustrate how the microbial stability varies among seasons in lake ecosystems. The results showed that the microbial networks were distinctly different among seasons, and the most complex network in autumn exhibited the highest stability. We found that the strong connecting structures among microbes (large modules) were significantly (P < 0.05) correlated with water temperature and pH, which would negatively affect keystone taxa and destabilize microbial communities. The networks with more keystone taxa were generally stable and the removal of keystone taxa would result in unstable networks. Moreover, the keystone taxa were specific among seasons due to environmental filtering and relevant interspecific interactions. These results suggested that seasonal variations of environmental factors could influence microbial networks and community stability via the regulation of keystone taxa. Thus, the keystone taxa could be used as indicators to reflect the seasonal stability of microbial communities in lake ecosystems. These findings improve our understanding of the microbial seasonal co-occurrence patterns and reveal the mechanism how microbial communities maintain their seasonal stability in aquatic ecosystems.
The tissue engineering approach for repairing osteochondral (OC) defects involves the fabrication of a biological tissue scaffold that mimics the physiological properties of natural OC tissue (
e.g.
..., the gradient transition between the cartilage surface and the subchondral bone). The OC tissue scaffolds described in many research studies exhibit a discrete gradient (
e.g.
, a biphasic or tri/multiphasic structure) or a continuous gradient to mimic OC tissue attributes such as biochemical composition, structure, and mechanical properties. One advantage of a continuous gradient scaffold over biphasic or tri/multiphasic tissue scaffolds is that it more closely mimics natural OC tissue since there is no distinct interface between each layer. Although research studies to this point have yielded good results related to OC regeneration with tissue scaffolds, differences between engineered scaffolds and natural OC tissue remain; due to these differences, current clinical therapies to repair OC defects with engineered scaffolds have not been successful. This paper provides an overview of both discrete and continuous gradient OC tissue scaffolds in terms of cell type, scaffold material, microscale structure, mechanical properties, fabrication methods, and scaffold stimuli. Fabrication of gradient scaffolds with three-dimensional (3D) printing is given special emphasis due to its ability to accurately control scaffold pore geometry. Moreover, the application of computational modeling in OC tissue engineering is considered; for example, efforts to optimize the scaffold structure, mechanical properties, and physical stimuli generated within the scaffold-bioreactor system to predict tissue regeneration are considered. Finally, challenges associated with the repair of OC defects and recommendations for future directions in OC tissue regeneration are proposed.
The tissue engineering approach for repairing osteochondral (OC) defects involves the fabrication of a biological tissue scaffold that mimics the physiological properties of natural OC tissue (
e.g.
, the gradient transition between the cartilage surface and the subchondral bone).
The emergence of various e-commerce sites has led to an increase in review sites for various services and products. People nowadays easily get information about products and services that will be ...used through reviews. Here sentiment analysis plays an important role in classifying the polarity of product reviews. However, with a large number of reviews, a sentiment analysis that only gives overall polarity is not sufficient. This will make it difficult to find the reviews of certain aspects (features) of the product. Aspect-based sentiment analysis as fine-grained sentiment analysis is able to provide specific polarity for each aspect contained in a sentence. Various kinds of development methods have been carried out to provide accurate results in aspect-based sentiment analysis. This paper will discuss the various deep learning methods that have been carried out and provide the possibility of research that can be carried out from Aspect-Based Sentiment Analysis.
Trifluoromethyl‐bearing 5‐membered rings are prevalent in bioactive molecules, but modular approaches to these compounds by functionalization of robust C(sp3)−H bonds in a direct and selective manner ...are extremely challenging. Herein we report the rhodium‐catalyzed α‐CF3‐α‐alkyl carbene insertion into C(sp3)−H bonds of a broad range of substrates to access 7 types of CF3‐bearing saturated 5‐membered carbo‐ and heterocycles. The reaction is particularly effective for benzylic C−H insertion exerting good site‐, diastereo‐ and enantiocontrol, and applicable to the synthesis of chiral CF3 analogues of bioactive molecules. Ruthenium α‐CF3‐α‐alkyl carbene complexes underwent stoichiometric reactions to give C−H insertion products, lending evidence for the involvement of metal α‐CF3‐α‐alkyl carbene species in the catalytic cycle. DFT calculations revealed that the π⋅⋅⋅π attraction and intra‐carbene C−H⋅⋅⋅F hydrogen bond elucidate the origin of selectivity of the benzylic C−H insertion reactions.
A modular approach to access CF3‐bearing 5‐membered carbo‐ and heterocycles via catalytic C (sp3)−H insertion is demonstrated. In the case of carbocycles, an asymmetric benzylic C−H insertion process allowed to reach high regio‐, diastereo‐ and enantioselectivities. This protocol can be applied to the synthesis of chiral CF3 analogues of medicinal agents and natural products. The origin of selectivity was investigated by DFT calculations.
The rise of multi-cloud systems has been spurred. For safety-critical missions, it is important to guarantee their security and reliability. To address trust constraints in a heterogeneous ...multi-cloud environment, this work proposes a novel scheduling method called matching and multi-round allocation (MMA) to optimize the makespan and total cost for all submitted tasks subject to security and reliability constraints. The method is divided into two phases for task scheduling. The first phase is to find the best matching candidate resources for the tasks to meet their preferential demands including performance, security, and reliability in a multi-cloud environment; the second one iteratively performs multiple rounds of re-allocating to optimize tasks execution time and cost by minimizing the variance of the estimated completion time. The proposed algorithm, the modified cuckoo search (MCS), hybrid chaotic particle search (HCPS), modified artificial bee colony (MABC), max-min, and min-min algorithms are implemented in CloudSim to create simulations. The simulations and experimental results show that our proposed method achieves shorter makespan, lower cost, higher resource utilization, and better trade-off between time and economic cost. It is more stable and efficient.
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