Mammalian Wnt proteins are believed to act as short-range signals, yet have not been previously visualized in vivo. Self-renewal, proliferation and differentiation are coordinated along a putative ...Wnt gradient in the intestinal crypt. Wnt3 is produced specifically by Paneth cells. Here we have generated an epitope-tagged, functional Wnt3 knock-in allele. Wnt3 covers basolateral membranes of neighbouring stem cells. In intestinal organoids, Wnt3-transfer involves direct contact between Paneth cells and stem cells. Plasma membrane localization requires surface expression of Frizzled receptors, which in turn is regulated by the transmembrane E3 ligases Rnf43/Znrf3 and their antagonists Lgr4-5/R-spondin. By manipulating Wnt3 secretion and by arresting stem-cell proliferation, we demonstrate that Wnt3 mainly travels away from its source in a cell-bound manner through cell division, and not through diffusion. We conclude that stem-cell membranes constitute a reservoir for Wnt proteins, while Frizzled receptor turnover and 'plasma membrane dilution' through cell division shape the epithelial Wnt3 gradient.
In this paper, a new load frequency control (LFC) for multi-area power systems is developed based on the direct-indirect adaptive fuzzy control technique. LFCs for each area are designed based on ...availability of frequency deviation of each area and tie-line power deviation between areas. The fuzzy logic system approximation capabilities are exploited to develop suitable adaptive control law and parameter update algorithms for unknown interconnected LFC areas. An H ∞ tracking performance criterion is introduced to minimize the approximation errors and the external disturbance effects. The proposed controller guarantees stability of the overall closed-loop system. Simulation results for a real three-area power system prove the effectiveness of the proposed LFC and show its superiority over a classical PID controller and a type-2 fuzzy controller.
Creating electrically conductive polymer composites with extremely low nanofiller concentration by melt compounding is a major research challenge. At low nanofiller concentration, the valuable ...properties of polymers are preserved and the feasibility of the composite is promoted. In this work, an organically modified clay (OMC) was utilized to alter the structure and consequently the electrical resistivity of carbon nanotubes (CNT)/polypropylene (PP) composite. As a result of OMC incorporation, the electrical percolation threshold concentration (EPTC) was reduced from 1.0 wt% CNT for the CNT/PP composite to 0.5 wt% CNT for the CNT:OMC/PP composite, corresponding to 50% reduction in the amount of CNT. The macro-dispersion analysis did not reveal any significant difference between the dispersion of CNT in the CNT/PP and CNT:OMC/PP composites. However, the processing behavior analysis showed a significant decrease in mixing torque and consequently mixing energy due to the addition of OMC. The decrease in mixing torque and/or mixing energy decreases the destruction of CNT aspect ratio. In addition, the DSC analysis showed a decrease in composite crystallinity due to OMC addition. This finding reveals a thinner insulating crystalline layer at the surface of CNT particles and consequently higher electrical conductivity. Based on these experimental findings, it can be speculated that the addition of OMC promoted the conductivity of the composite by decreasing the mixing shear stress and/or polymer crystallinity.
•We present a new improvement to the grey wolf algorithm.•The new improvement is tested with twenty-three benchmark functions.•The new improvement is compared with four published algorithms.•The new ...improvement is applied to grid-connected wind power plants.•The new improvement is verified by simulation results.
The grey wolf optimizer (GWO) is a new meta-heuristic algorithm inspired from the leadership and prey searching, encircling, and hunting of the grey wolves’ community. The GWO algorithm has the advantages of simplicity (less control parameters), flexibility, and globalism. In this paper, a simple and efficient augmentation for the GWO (AGWO) algorithm is proposed for better hunting performance. The AGWO algorithm focuses on increasing the possibility of the exploration process over the exploitation process by modifying the behavior of the control parameter (a) and position updating. The AGWO is suitable to the low number of search agents such as the electric power system application. The proposed AGWO algorithm is verified using twenty-three benchmark test functions and is applied to the grid-connected permanent magnet synchronous generator driven by variable speed wind turbine (PMSG-VSWT). The obtained results of the AGWO algorithm are compared with the results of the original GWO and other algorithms. The comparisons verified that the proposed AGWO is significantly augmented the performance of the original GWO algorithm without affecting its simplicity and easy implementation.
The aim of this study was to assess the shear bond strength of 3D-printed and milled provisional restorations using various resin materials and surface finishes. There were 160 preliminary samples in ...all, and they were split into two groups: the milled group and the 3D-printed group. Based on the resin used for repair (composite or polymethylmethacrylate (PMMA)) and the type of surface treatment utilized (chemical or mechanical), each group was further divided into subgroups. The specimens were subjected to thermocycling from 5 °C to 55 °C for up to 5000 thermal cycles with a dwell time of 30 s. The mechanical qualities of the repaired material underwent testing for shear bond strength (SBS). To identify the significant differences between the groups and subgroups, a statistical analysis was carried out. Three-way ANOVA was used to analyze the effects of each independent component (the material and the bonding condition), as well as the interaction between the independent factors on shear bond strength. Tukey multiple post-hoc tests were used to compare the mean results for each material under various bonding circumstances. The shear bond strengths of the various groups and subgroups differed significantly (p < 0.05). When compared to the milled group, the 3D-printed group had a much greater mean shear bond strength. When compared to PMMA repair, the composite resin material showed a noticeably greater shear bond strength. In terms of surface treatments, the samples with mechanical and chemical surface treatments had stronger shear bonds than those that had not received any. The results of this study demonstrate the effect of the fabrication method, resin type, and surface treatment on the shear bond strength of restored provisional restorations. Particularly when made using composite material and given surface treatments, 3D-printed provisional restorations showed exceptional mechanical qualities. These results can help dentists choose the best fabrication methods, resin materials, and surface treatments through which to increase the durability and bond strength of temporary prosthesis.
Purpose
The purpose of this paper is to investigate the impact of servant leadership on work engagement and affective commitment among academics in higher education. Moreover, the paper highlights ...the role of job satisfaction as an intervening mechanism among the examined variables.
Design/methodology/approach
Self-administered questionnaires were distributed to academics working in the Palestinian higher education sector. We used structural equation modelling to examine the hypotheses.
Findings
A positive relationship was found between servant leadership and affective commitment. The relationship between servant leadership and work engagement is fully mediated by job satisfaction, whereas partial mediation was found between servant leadership and affective commitment. Both work engagement and affective commitment have a positive impact on academics’ job performance.
Practical implications
The paper provides a fertile ground for higher education managers concerning the role of leadership in stimulating work engagement and organisational commitment among academics.
Originality/value
First, the paper is one of the few studies that empirically examines servant leadership in higher education using data coming from a non-Western context because most of the servant leadership research is conducted in the Western part of the world (Parris and Peachey, 2013). Second, we empirically provide evidence for the argument that servant leadership is needed in higher education. Third, the paper contributes to the limited body of research on work engagement and commitment in the higher education sector.
Background Most children with detectable peanut-specific IgE (P-sIgE) are not allergic to peanut. We addressed 2 non–mutually exclusive hypotheses for the discrepancy between allergy and ...sensitization: (1) differences in P-sIgE levels between children with peanut allergy (PA) and peanut-sensitized but tolerant (PS) children and (2) the presence of an IgE inhibitor, such as peanut-specific IgG4 (P-sIgG4 ), in PS patients. Methods Two hundred twenty-eight children (108 patients with PA, 77 PS patients, and 43 nonsensitized nonallergic subjects) were studied. Levels of specific IgE and IgG4 to peanut and its components were determined. IgE-stripped basophils or a mast cell line were used in passive sensitization activation and inhibition assays. Plasma of PS subjects and patients submitted to peanut oral immunotherapy (POIT) were depleted of IgG4 and retested in inhibition assays. Results Basophils and mast cells sensitized with plasma from patients with PA but not PS patients showed dose-dependent activation in response to peanut. Levels of sIgE to peanut and its components could only partially explain differences in clinical reactivity between patients with PA and PS patients. P-sIgG4 levels ( P = .023) and P-sIgG4 /P-sIgE ( P < .001), Ara h 1–sIgG4 /Ara h 1–sIgE ( P = .050), Ara h 2–sIgG4 /Ara h 2–sIgE ( P = .004), and Ara h 3–sIgG4 /Ara h 3–sIgE ( P = .016) ratios were greater in PS children compared with those in children with PA. Peanut-induced activation was inhibited in the presence of plasma from PS children with detectable P-sIgG4 levels and POIT but not from nonsensitized nonallergic children. Depletion of IgG4 from plasma of children with PS (and POIT) sensitized to Ara h 1 to Ara h 3 partially restored peanut-induced mast cell activation ( P = .007). Conclusions Differences in sIgE levels and allergen specificity could not justify the clinical phenotype in all children with PA and PS children. Blocking IgG4 antibodies provide an additional explanation for the absence of clinical reactivity in PS patients sensitized to major peanut allergens.
Cloud computing is a recent and significant development in the domain of network applications with a new information technology perspective. This study attempts to develop a hybrid model to predict ...motivators influencing the adoption of cloud computing services by information technology (IT) professionals. The research proposes a new model by extending the Technology Acceptance Model (TAM) with three external constructs namely computer self-efficacy, trust, and job opportunity. One of the main contributions of this research is the introduction of a new construct, Job Opportunity (JO), for the first time in a technology adoption study. Data were collected from 101 IT professional and analyzed using multiple linear regression (MLR) and neural network (NN) modeling. Based on the RMSE values from the results of these models NN models were found to outperform the MLR model. The results obtained from MLR showed that computer self-efficacy, perceived usefulness, trust, perceived ease of use, and job opportunity. However, the NN models result showed that the best predictor of cloud computing adoption are job opportunity, trust, perceived usefulness, self-efficacy, and perceived ease of use. The findings of this study confirm the need to extend the fundamental TAM when studying a recent technology like cloud computing. This study will provide insights to IT service providers, government agencies, academicians, researchers and IT professionals.
•An understanding of factors influencing adoption of cloud computing services by individual users in a workplace setting.•A hybrid model including Multiple Linear Regression and Neural Network Modeling is proposed.•A new construct, “job opportunity” is introduced.•The two most important factors influencing cloud computing adoption are job opportunity and trust.
A path planning and control approach of a non-holonomic three-wheeled mobile robot (WMR) for online navigation in road following and roundabout environments is presented in this paper. We proposed a ...complete navigation algorithm that enables the WMR to autonomously navigate on the road with various scenarios. With such an algorithm, the robot is able to localize itself within the road environment and find a collision free-path starting from a pre-defined start position to a goal point using a novel approach called laser simulator (LS). The path planning and roundabout detection are determined based on LS and sensor fusion of a laser range finder, camera, and odometry measurements. The sensor fusion algorithm is used to remove noises and uncertainties from sensors' data and provide optimum measurements for path planning. A robot motion control scheme is used for the purpose of controlling the kinematic parameters of WMR using a resolved acceleration control coupled with an active force control for rejecting the disturbances. Experimental results show the capability of the proposed algorithms to robustly drive the robot on the road following and roundabout environments.
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