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Motivation Intercellular communication (i.e. cell–cell communication) plays an essential role in multicellular organisms coordinating various biological processes. Previous studies discovered that feedback loops between two cell types are a widespread and vital signaling motif regulating development, regeneration and cancer progression. While many computational methods have been developed to predict cell–cell communication based on gene expression datasets, these methods often predict one-directional ligand–receptor interactions from sender to receiver cells and are not suitable to identify feedback loops. Results Here, we describe ligand–receptor loop (LRLoop), a new method for analyzing cell–cell communication based on bi-directional ligand–receptor interactions, where two pairs of ligand–receptor interactions are identified that are responsive to each other and thereby form a closed feedback loop. We first assessed LRLoop using bulk datasets and found our method significantly reduces the false positive rate seen with existing methods. Furthermore, we developed a new strategy to assess the performance of these methods in single-cell datasets. We used the between-tissue interactions as an indicator of potential false-positive prediction and found that LRLoop produced a lower fraction of between-tissue interactions than traditional methods. Finally, we applied LRLoop to the single-cell datasets obtained from retinal development. We discovered many new bi-directional ligand–receptor interactions among individual cell types that potentially control proliferation, neurogenesis and/or cell fate specification. Availability and implementation An R package is available at https://github.com/Pinlyu3/LRLoop. The source code can be found at figshare (https://doi.org/10.6084/m9.figshare.20126138.v1). The datasets can be found at figshare (https://doi.org/10.6084/m9.figshare.20126021.v1). Supplementary information Supplementary data are available at Bioinformatics online. [ABSTRACT FROM AUTHOR]

The grid-connected control technology of ac/dc hybrid microgrids affects power quality, stability, robustness, and other indicators. In order to achieve high-quality and reliability of ac/dc hybrid microgrids connected to a distributed network, this paper proposes a robust control method for grid-connected ac/dc hybrid microgrids based on mixed sensitivity. First, the grid-connected model of ac/dc hybrid microgrids is equivalent to the superposition theorem; then, the problem of how to control grid-connection can be transformed to the problem of how to deal with mixed sensitivity by considering the influence of the distributed network on ac/dc hybrid microgrids as a disturbance. Second, the grid-connected robust controller can be obtained by using the Riccati method repeatedly, which can ensure good nominal performance of the system and enhance the robustness of the system. Finally, the validity and feasibility of the proposed control method can be verified with three simulation conditions. [ABSTRACT FROM AUTHOR]

Summary Developing tissues dictate the amount and type of innervation they require by secreting neurotrophins, which promote neuronal survival by activating distinct tyrosine kinase receptors. Here, we show that nerve growth factor (NGF) signaling through neurotrophic tyrosine kinase receptor type 1 (TrkA) directs innervation of the developing mouse femur to promote vascularization and osteoprogenitor lineage progression. At the start of primary ossification, TrkA-positive axons were observed at perichondrial bone surfaces, coincident with NGF expression in cells adjacent to centers of incipient ossification. Inactivation of TrkA signaling during embryogenesis in TrkA F592A mice impaired innervation, delayed vascular invasion of the primary and secondary ossification centers, decreased numbers of Osx-expressing osteoprogenitors, and decreased femoral length and volume. These same phenotypic abnormalities were observed in mice following tamoxifen-induced disruption of NGF in Col2-expressing perichondrial osteochondral progenitors. We conclude that NGF serves as a skeletal neurotrophin to promote sensory innervation of developing long bones, a process critical for normal primary and secondary ossification. [ABSTRACT FROM AUTHOR]

Abstract: With increasing concern over greenhouse gas (GHG) emission, more and more wind turbines are connected to electric power systems. Since many of these new wind farms employ doubly-fed induction generators (DFIG), power engineers find it is necessary to understand the characteristics of the DFIG better. This paper presents the DFIG as a synchronous/asynchronous hybrid. Like the synchronous generator, the real power characteristics are shown to depend on the rotor voltage magnitude |V R| and angle δ. Like the induction machine, the real power characteristics also depend on the slip s. [Copyright &y& Elsevier]

An intraday, multi-objective, hierarchical and coordinated operation scheduling method for a multi-energy system (MES), which uses 15-min and 5-min scheduling intervals for different energy subsystems, is proposed. According to the characteristics of MES and the response time of energy conversion equipment, energy subsystems are dispatched on different dispatch intervals instead of unified dispatch intervals to dispatch energy subsystems. In a case study, the prediction error rate for a load is 5% and 2% when the dispatch interval is 15 min and 5 min, respectively; the prediction error rates for wind and solar energy output are 10% and 5%, respectively. Dispatching different subsystems with different intervals according to their characteristics reduces the impact of source and load uncertainties, which improves energy management. Multi-energy power dispatch considers exergy efficiency and the operation cost to improve the utilization energy efficiency. The Tchebycheff method, which considers the fuzzy entropy weight, is employed to balance the objectives between highest exergy efficiency and lowest operation cost. Numerical studies demonstrate that the operation cost of a multi-objective system is ¥500.8877 higher than that of a system with the objective of lowest operation cost. The exergy efficiency is increased by 3.94%, and the operation cost, which is reduced by ¥1706.9606, is 2.13% lower than that for the objective of highest exergy efficiency. Thus, the proposed method can balance the objectives between highest exergy efficiency and lowest operation cost. These findings provide a multi-dimensional dispatch scheme for dispatchers and highlight the development potential of an MES. • An intraday two-stage multi-objective dispatch method for a MES is proposed. • The power are scheduled considering varied response times of MES. • Two objectives of highest exergy efficiency and lowest operation cost are considered. [ABSTRACT FROM AUTHOR]