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To address the problems of network congestion and spectrum resources shortage in multi-user large-scale scenarios, this paper proposes a twice random access OFDMA-NOMA-RA protocol combining the advantages of orthogonal frequency division multiple access (OFDMA) and non-orthogonal multiple access (NOMA). The idea of this protocol is that OFMDA is used to divide the entire frequency field into multiple orthogonal resource units (RUs), and NOMA is used on each RU to enable more users to access the channel and improve spectrum efficiency. Based on the protocol designed in this paper, in the case of imperfect successive interference cancellation (SIC), the probability of successful competition subchannels and the outage probability are derived for two scenarios: Users occupy the subchannel individually and users share the subchannel. Moreover, when two users share the channel, the decoding order of the users and the corresponding probabilities are considered. Then, the system throughput is obtained. To achieve better outage performance in the system, the optimal power allocation algorithm is proposed in this paper, which enables the optimal power allocation strategy to be obtained. Numerical results show that the larger the imperfect SIC coefficient, the worse the outage performance of weak users. Compared with pure OFDMA and NOMA, OFDMA-NOMA-RA always maintains an advantage when the imperfect SIC coefficient is less than a specific value. [ABSTRACT FROM AUTHOR]

Aims: During the COVID-19 epidemic, nurses played a crucial role in clinical treatment. As a special group, front-line nurses, especially those assigned to support Hubei Province in the fight against COVID-19 between February and April 2020, brought diverse experiences from different provinces in China in taking care of COVID-19 patients and role cognition. Therefore, our purpose is to explore the real coping experience and role cognition of front-line nurses during the novel coronavirus outbreak to provide relevant experience references for society and managers in the face of such major public health emergencies in the future. Design: This qualitative study was performed using the phenomenological hermeneutics method. Method: This is a qualitative phenomenological study. Semi-structured in-depth interviews were used to collect data. The interviewees were 53 front-line nurses who assisted and supported the fight against COVID-19 in Hubei Province during the COVID-19 epidemic. Data were collected through individual online and telephone interviews using a semi-structured interview during March 2020. The COREQ guidance was used to report this study. Results: The findings revealed that front-line nurses assisting in the fight against COVID-19 developed a context-specific role cognition of their work and contribution to society. The qualitative analysis of the data revealed 15 subcategories and 5 main categories. These five themes represented the different roles identified by nurses. The roles included expectations, conflicts, adaptation, emotions, and flow of blessing. Belief in getting better, a sense of honor, and training could help them to reduce feelings of conflict in this role and adapt more quickly. Discussion: This article discusses the real coping experience and role cognition of front-line nurses during the novel coronavirus epidemic. It provides relevant experience references for society and managers to face similar major public health emergencies in the future. This study makes a significant contribution to the literature because it demonstrates how non-local nurses sent to Hubei to work perceived their roles as part of a larger narrative of patriotism, duty, solidarity, and hope. [ABSTRACT FROM AUTHOR]

As a non-toxic copolymer of isobutylene and maleic anhydride, Isobam is successfully used as a dispersant and a gelling agent for fabricating porous Si3N4 ceramics by gel casting. The dispersity and rheological properties of the Si3N4 slurry are influenced by the pH, milling time, and Isobam content which varies from 0.1 ​wt.% to 0.6 ​wt.%, and these factors are investigated. The slurry with 40 ​vol.% solid content and milled for 4 ​h has a high zeta potential at pH 12 (adjusted by Tetramethyl ammonium hydroxide (TMAH)), which means that the particles are well dispersed. The mechanisms of TMAH are electrostatic repulsion and steric hindrance. The viscosity of the slurry increases with the increase of Isobam content. After pressureless sintering at 1700 ​°C for 2 ​h, a uniform unique interlocking microstructure of rod-like β-Si3N4 grains is observed, which may improve the flexural strength of the ceramics by intergranular fracture and particle pullout of β-Si3N4 grains. The density and porosity of the samples fluctuate negligibly with the increase of Isobam content, and the Si3N4 ceramic with 0.1 ​wt.% Isobam exhibits the highest bending strength of 251.6 ​MPa among all samples. [ABSTRACT FROM AUTHOR]

The present study aimed to screen potential target genes for the early diagnosis and treatment of early metastatic clear cell renal cell carcinoma (ccRCC) using the microarray data of early metastatic and non-metastatic ccRCC samples. The DNA microarray dataset GSE47352 was downloaded from Gene Expression Omnibus and included 4 early metastatic and 5 non-metastatic ccRCC samples. Differentially expressed genes (DEGs) were screened using the limma package. Then, pheatmap package was used to conduct two-way clustering for the DEGs. Subsequently, MAPPFinder and GenMAPP were employed separately to perform functional and pathway enrichment analysis for the DEGs. Additionally, a protein-protein interaction (PPI) network was constructed using Cytoscape, and small drug molecules were searched using Connectivity map (cmap). In total, 196 upregulated and 163 downregulated genes were identified. DEGs, including JUN, tumor necrosis factor (TNF), Ras homolog family member B (RHOB) and transforming growth factor ß2 (TGFß2) were significantly enriched in the signaling pathway of renal cell carcinoma. Furthermore, nuclear receptor subfamily 4 group A member 1 (NR4A1) was significantly enriched in the mitogen-activated protein kinase signaling pathway; in addition, laminin subunit a (LAMA) 1, LAMA2 and LAMA4 were significantly enriched in extracellular matrix-receptor interaction. JUN (degree=6) had the highest degree in the PPI network. Thapsigargin (score=-0.913) possessed the highest performance in terms of the treatment of early metastatic ccRCC. In the present study, it was discovered that certain DEGs, including JUN, TNF, RHOB, NR4A1, TGFß2, LAMA1, LAMA2 and LAMA4 were potential target genes associated with early metastatic ccRCC. In addition, thapsigargin could be used as an efficient small drug molecule for the treatment of early metastatic ccRCC. [ABSTRACT FROM AUTHOR]

Tub 2.1, a monoclonal antibody commonly used to measure cellular tubulin content, is widely believed to recognize all β-tubulin isotypes. Though it has been used for more than two decades, the epitope for this antibody is not well established. We report for the first time that contrary to common belief, this antibody does not react with all isotypes of β-tubulin. Of the seven vertebrate β-tubulins, the more divergent class V and VI isotypes are not recognized by this antibody. Among the isotypes that do react, binding is similar for β2, β3, β4a and β4b but lower for β1, the most abundant isotype. Expression of chimeric tubulins verified that the epitope for Tub 2.1 is near the C-terminal end of β-tubulin. Site-directed mutagenesis of this region in nonreactive β5 to match the sequence of β4b resulted in strong reaction to Tub 2.1 and narrowed the epitope to amino acids 431–436. [ABSTRACT FROM PUBLISHER]

The T-peel fractured surfaces of bonded films of ethylene/1-octene copolymers with different 1-octene contents were characterized using atomic force microscopy (AFM) and analyzed by fractal analysis. The AFM images showed strong dependence on the bonding temperature, peel rate, and the 1-octene content visually. This dependence has been demonstrated quantitatively by the fractal analyses which quantified an irregular surface by fractal dimensions and characteristic sizes. Two regimes showing fractal features were identified for each surface. In Regime I (higher magnifications) the welding and the following T-peel fracture procedures did little to change the fractal dimensions compared with the original surfaces before welding. But there were significant changes in Regime II (lower magnification) before welding and after T-peel fracture tests. The length scale that separated these two regimes is of the same order as that of polyethylene lamellar crystal structures. This suggests that the amorphous chains interdiffused across the interface while unmelted interfacial crystal structures remain essentially unaltered during the autohesion process. A "stitch-welding" autohesion mechanism was proposed to describe the bonding process in which only chains in the amorphous portions could interdiffuse. During the T-peel fracture tests, a crystal structure on the interface is either pulled over to the other side of the interface due to the interdiffused chains, remains unchanged, or is used as an anchor to pull a crystal structure from the other side of the interface. The characteristic sizes at which the fractal characteristics emerge were shown to be larger for the surfaces fractured at higher peel rates, which corresponds to higher fracture energy. This suggests that the appearance of fractal behavior at larger scales requires higher fracture energies. The characteristic sizes and fractal dimensions were also shown to depend on the molecular structure. [ABSTRACT FROM AUTHOR]

We introduce a class of Bayesian infinite mixture models first introduced by Lo (1984) to determine the credibility premium for a non-homogeneous insurance portfolio. The Bayesian infinite mixture models provide us with much flexibility in the specification of the claim distribution. We employ the sampling scheme based on a weighted Chinese restaurant process introduced in Lo et al. (1996) to estimate a Bayesian infinite mixture model from the claim data. The Bayesian sampling scheme also provides a systematic way to cluster the claim data. This can provide some insights into the risk characteristics of the policyholders. The estimated credibility premium from the Bayesian infinite mixture model can be written as a linear combination of the prior estimate and the sample mean of the claim data. Estimation results for the Bayesian mixture credibility premiums will be presented. [ABSTRACT FROM AUTHOR]