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Modal global linear stability analysis of thermal convection is performed with the linearized lattice Boltzmann method (LLBM). The onset of Rayleigh–Bénard convection in rectangular cavities with conducting and adiabatic sidewalls and the instability of two-dimensional (2-D) and three-dimensional (3-D) natural convection in cavities are studied. The method of linearizing the local equilibrium probability distribution function that was first proposed by Pérez et al. (Theor. Comp. Fluid Dyn., vol. 31, 2017, pp. 643–664) is extended to solve the coupled linear Navier–Stokes equations together with the linear energy equation in this work. A multiscale analysis is also performed to recover the macroscopic linear Navier–Stokes equations from the discrete lattice Boltzmann equations for both the single and multiple relaxation time models. The present LLBM is implemented in the framework of the Palabos library. It is validated by calculating the linear critical value of 2-D natural convection that the LLBM with the multiple relaxation time model has an error less than 1 % compared with the spectral method. The instability mechanism of the flow is explained by kinetic energy transfer analysis. It is shown that the buoyancy mechanism and inertial mechanism tend to stabilize the Hopf bifurcation of the 2-D natural convection at Pr < 0.08 and Pr > 1, respectively. For 3-D natural convection, subcritical bifurcation of the Hopf type is found for low-Prandtl-number fluids (Pr < 0.1).
Ahsan, Sinha, and Srinivasan (2020) studied the motives of knowledge-intensive Indian firms’ international expansion based on resource-based considerations and the locational advantages offered by host countries. They identified firm characteristics associated with strategic asset-seeking, opportunity-seeking, and market-seeking motives. In this replication study, we examine Ahsan et al.'s (2020) model in the Chinese context. Based on our improved empirical model, our findings reveal some similarities but more importantly some key differences in the antecedents of internationalization motives between Indian and Chinese firms. Drawing on insights from prior studies, we propose that these differences can be attributed to differences in absorptive capacity, international expansion scales and patterns, ownership type, and the home institutional contexts in which Indian and Chinese firms operate. Overall, this replication study demonstrates the importance of contextualizing international business research.
Topological transition and helicity conversion of vortex torus knots and links are studied using direct numerical simulations of the incompressible Navier–Stokes equations. We find three topological transitional routes (viz. merging, reconnection and transition to turbulence) in the evolution of vortex knots and links over a range of torus aspect ratios and winding numbers. The topological transition depends not only on the initial topology but also on the initial geometry of knots/links. For small torus aspect ratios, the initially knotted or linked vortex tube rapidly merges into a vortex ring with a complete helicity conversion from the writhe and link components to the twist. For large torus aspect ratios, the vortex knot or link is untied into upper and lower coiled loops via the first vortex reconnection, with a helicity fluctuation including loss of writhe and link, and generation of twist. Then, the relatively unstable lower loop can undergo a secondary reconnection to split into multiple small vortices with a similar helicity fluctuation. Surprisingly, for moderate torus aspect ratios, the incomplete reconnection of tangled vortex loops together with strong vortex interactions triggers transition to turbulence, in which the topological helicity decomposition fails due to the breakdown of vortex core lines.
The subduction model of the Neo-Tethys during the Early Cretaceous has always been a controversial topic, and the scarcity of Early Cretaceous magmatic rocks in the southern part of the Gangdese batholith is the main cause of this debate. To address this issue, this article presents new zircon U–Pb chronology, zircon Hf isotope, whole-rock geochemistry and Sr–Nd isotope data for the Early Cretaceous quartz diorite dykes with adakite affinity in Liuqiong, Gongga. Zircon U–Pb dating of three samples yielded ages of c. 141–137 Ma, indicating that the Liuqiong quartz diorite was emplaced in the Early Cretaceous. The whole-rock geochemical analysis shows that the Liuqiong quartz diorite is enriched in large-ion lithophile elements (LILEs) and light rare-earth elements (LREEs) and is depleted in high-field-strength elements (HFSEs), which are related to slab subduction. Additionally, the Liuqiong quartz diorite has high SiO2, Al2O3 and Sr contents, high Sr/Y ratios and low heavy rare-earth element (HREE) and Y contents, which are compatible with typical adakite signatures. The initial 87Sr/86Sr values of the Liuqiong adakite range from 0.705617 to 0.705853, and the whole-rock ϵNd(t) values vary between +5.78 and +6.24. The zircon ϵHf(t) values vary from +11.5 to +16.4. Our results show that the Liuqiong adakite magma was derived from partial melting of the Neo-Tethyan oceanic plate (mid-ocean ridge basalt (MORB) + sediment + fluid), with some degree of subsequent peridotite interaction within the overlying mantle wedge. Combining regional data, we favour the interpretation that the Neo-Tethyan oceanic crust was subducted at a low angle beneath the Gangdese during the Early Cretaceous.
In this paper, effects of discharge parameters and modulation frequency on the signal of laser-induced fluorescence measurements of ion velocity distribution functions are investigated in the LIF Test Source. A maximum modulation frequency is found for each given set of parameters, beyond which the signal gradually declines. Meanwhile, this maximum modulation frequency occurred consistently at ~1/10 of the theoretical frequency limit and photon counts received by a photomultiplier tube, which indicates that as modulation frequency and the associated per-pulse-excitation-event count decrease, the transition from the macroscopic statistical signal to the microscopic probabilistic signal is a gradual process.
In automotive digital development, 3D prototype creation is a team effort of designers and engineers, each contributing with ideas and technical evaluations through means of computer simulations. To support the team in the 3D design ideation and exploration task, we propose an interactive design system for assisted design explorations and faster performance estimations. We utilize the advantage of deep learning-based autoencoders to create a low-dimensional latent manifold of 3D designs, which is utilized within an interactive user interface to guide and strengthen the decision-making process.
This paper presents an approach for evaluating exoskeleton support concepts through biomechanical analyses on a musculoskeletal human model. By simplifying the support forces of an exoskeleton as external forces, different support concepts can be biomechanically evaluated for the respective use case without concrete design specifications of the exoskeleton. This enables an estimation of the resulting relief and strain on the human body in the early stages of exoskeleton development. To present the approach, the use case of working at and above head height with a power tool is chosen.
To date, there is limited evidence for health care providers regarding the determinants of early assessment of poor outcomes of adult in-patients due to earthquakes. This study aimed to explore factors related to early assessment of adult earthquake trauma patients (AETPs).
The data on 29,933 AETPs in the West China Earthquake Patients Database (WCEPD) were analyzed retrospectively. Then, 37 simple variables that could be obtained rapidly upon arrival at the hospital were collected. The least absolute shrinkage and selection operator (LASSO) regression analyses were performed. A nomogram was then constructed.
Nine independent mortality-related factors that contributed to AETP in-patient mortality were identified. The variables included age (OR:1.035; 95%CI, 1.027-1.044), respiratory rate ([RR]; OR:1.091; 95%CI, 1.050-1.133), pulse rate ([PR]; OR:1.028; 95%CI, 1.020-1.036), diastolic blood pressure ([DBP]; OR:0.96; 95%CI, 0.950-0.970), Glasgow Coma Scale ([GCS]; OR:0.666; 95%CI, 0.643-0.691), crush injury (OR:3.707; 95%CI, 2.166-6.115), coronary heart disease ([CHD]; OR:4.025; 95%CI, 1.869-7.859), malignant tumor (OR:4.915; 95%CI, 2.850-8.098), and chronic kidney disease ([CKD]; OR:5.735; 95%CI, 3.209-10.019).
The nine mortality-related factors for ATEPs, including age, RR, PR, DBP, GCS, crush injury, CHD, malignant tumor, and CKD, could be quickly obtained on hospital arrival and should be the focal point of future earthquake response strategies for AETPs. Based on these factors, a nomogram was constructed to screen for AETPs with a higher risk of in-patient mortality.
The Kármán–Howarth–Monin–Hill equation is employed to study the production and interscale energy transfer in a boundary layer undergoing bypass transition due to free-stream turbulence. The energy flux between different length scales is calculated at several streamwise locations covering the laminar, transitional and turbulent regimes. Maps of scale energy production and flux vectors are visualised on two-dimensional planes and three-dimensional hyper-planes that comprise both physical and separation spaces. In the transitional region, the maps show strong inverse cascade in the streamwise direction near the wall. The energy flux vectors emanate from a region of strong production and transfer energy to larger streamwise scales. To provide deeper insight into the origin of the inverse cascade process, we decompose the energy flux vector into components arising from nonlinear interactions between velocity fluctuations, mean flow inhomogeneity, pressure and viscous effects. The inverse cascade is mainly due to the nonlinear interaction component, and in the earliest stages of transition this component competes with that due to mean flow inhomogeneity. By superposing the instantaneous velocity fields and the energy flux vectors, we relate the inverse cascade process to the growth of turbulent spots. Once the transition process is complete, the maps become very similar to those observed in other fully developed turbulent flows, such as channel flow. Finally we characterise the nonlinear interaction term using probability density functions (PDFs) evaluated at different wall-normal heights. The PDFs are asymmetric and wide-skirted as in homogeneous isotropic turbulence, but are skewed towards positive values reflecting the inverse cascade.
Pneumatic muscle actuator (PMA) similar to biological muscle is a new type of pneumatic actuator. The flexible manipulator based on PMAs was constructed to simulate the actual movement of the human upper arm. Considering the model errors and external disturbances, the fuzzing sliding mode control based on the saturation function was proposed. Compared with other fuzzy control methods, fuzzy control and saturation function are used to adjust the robust terms to improve the tracking accuracy and reduce the high-frequency chattering.
The current COVID-19 pandemic contributed by the SARS-CoV-2 has put in place an urgent need for new and promising antiviral therapeutics. The viral RNA-dependent RNA polymerase (RdRp) enzyme plays a vital role in viral replication for all RNA viruses, including SARS-CoV-2, thereby making it a prime and promising candidate for novel antiviral targeting. Interestingly, the human telomerase reverse transcriptase (hTERT), a common catalytic subunit of the telomerase enzyme in many cancers, has also been identified with structural and functional similarities to the viral RdRp. Therefore, it becomes essential to evaluate and consider anticancer drugs that target hTERT towards antiviral RdRp activity, and vice versa. For instance, Floxuridine, an hTERT inhibitor, and VX-222, a hepatitis C virus RdRp inhibitor, are now gaining recognition as a potential antiviral against SARS-CoV-2 and anti-hTERT for cancer, simultaneously. While limited studies on hTERT inhibitors for use as viral RdRp, and anti-RdRp inhibitors as hTERT inhibitors are available, in this review, we aim at bringing to light this close structural and functional relationship between both these enzymes. We punctuate this idea with specific examples on how potential anticancer inhibitors can effectively be brought to use as inhibitors against the SARS-CoV-2 virus, a relatively new pathogen, compared to the very well-studied field of cancer research.
The fact that many Chinese business organizations incorporate social function units into their structures as well as social services into their practice has surprisingly received insufficient attention in organization studies. To theorize an organizational model that resembles community building in many aspects, we conduct case studies on this phenomenon and explain it from a new perspective, focusing on community arrangement within organizations. Our study draws on theoretical insights from institutional logic perspectives and builds a new conceptual schema through which to view organizations as communities. In our case studies of five firms in four cities, we find that, despite changes in the larger society, these Chinese firms built and maintained a model for organizations that communities can be embedded in organizations of various scales and in various industries. This community model of organizations offers new theoretical insights into organizations more broadly and has practical implications for improving the quality of employees’ work life.
Embryo quality determines the success of in vitro fertilization and embryo transfer (IVF-ET) treatment. Biomarkers for the evaluation of embryo quality have some limitations. Apoptosis in cumulus cells (CCs) is important for ovarian function. PTEN (phosphatase and tensin homolog) is a well known tumour suppressor gene that functions as a mediator of apoptosis and is crucial for mammalian reproduction. In the present study, we analyzed the expression level of PTEN in human CCs and aimed to investigate its association with embryo developmental competence in IVF treatment cycles. The PTEN mRNA level in CCs was measured using real-time fluorescence quantitative PCR. The association of the differential expression of PTEN with embryo quality was analyzed. Our data showed that PTEN mRNA levels were significantly decreased in CCs surrounding mature oocytes compared with immature oocytes. Similar changes were found in the analysis of fertilization and blastocyst formation. The speculation that the measurement of PTEN mRNA levels in human CCs would provide a useful tool for selecting oocytes with greater chances to implant into the uterus needs to be further verified through single-embryo transfer in the future. The proapoptotic mechanism of PTEN in human reproduction needs to be further studied.
Big data has been reported widely to facilitate epidemic prevention and control in health care during the coronavirus disease 2019 (COVID-19) pandemic. However, there is still a lack of practical experience in applying it to hospital prevention and control. This study is devoted to the practical experience of design and implementation as well as the preliminary results of an innovative big data-driven COVID-19 risk personnel screening management system in a hospital. Our screening system integrates data sources in four dimensions, which includes Health Quick Response (QR) code, abroad travelling history, transportation close contact personnel and key surveillance personnel. Its screening targets cover all patients, care partner and staff who come to the hospital. As of November 2021, nearly 690 000 people and 5.79 million person-time had used automated COVID-19 risk screening and monitoring. A total of 10 376 person-time (0.18%) with abnormal QR code were identified, 242 person-time with abroad travelling history were identified, 925 person-time were marked based on the data of key surveillance personnel, no transportation history personnel been reported and no COVID-19 nosocomial infection occurred in the hospital. Through the application of this system, the hospital's expenditure on manpower and material resources for epidemic prevention and control has also been significantly reduced. Collectively, this study has proved to be an effective and efficient model for the use of digital health technology in response to the COVID-19 pandemic. Based on the data from multiple sources, this system has an irreplaceable role in identifying close contacts or suspicious person, and can significantly reduce the social burden caused by COVID-19, especially the human resources and economic costs of hospital prevention and control. It may provide guidance for clinical epidemic prevention and control in hospitals, as well as for future public health emergencies.
The role of neurological proteins in the development of bipolar disorder (BD) and schizophrenia (SCZ) remains elusive now. The current study aims to explore the potential genetic correlations of plasma neurological proteins with BD and SCZ.
By using the latest genome-wide association study (GWAS) summary data of BD and SCZ (including 41,917 BD cases, 11,260 SCZ cases, and 396,091 controls) derived from the Psychiatric GWAS Consortium website (PGC) and a recently released GWAS of neurological proteins (including 750 individuals), we performed a linkage disequilibrium score regression (LDSC) analysis to detect the potential genetic correlations between the two common psychiatric disorders and each of the 92 neurological proteins. Two-sample Mendelian randomisation (MR) analysis was then applied to assess the bidirectional causal relationship between the neurological proteins identified by LDSC, BD and SCZ.
LDSC analysis identified one neurological protein, NEP, which shows suggestive genetic correlation signals for both BD (coefficient = −0.165, p value = 0.035) and SCZ (coefficient = −0.235, p value = 0.020). However, those association did not remain significant after strict Bonferroni correction. Two sample MR analysis found that there was an association between genetically predicted level of NEP protein, BD (odd ratio [OR] = 0.87, p value = 1.61 × 10−6) and SCZ (OR = 0.90, p value = 4.04 × 10−6). However, in the opposite direction, there is no genetically predicted association between BD, SCZ, and NEP protein level.
This study provided novel clues for understanding the genetic effects of neurological proteins on BD and SCZ.
Autoimmune thyroiditis (AIT) has a complex aetiology and the susceptibility to it is determined by a combination of genetic and environmental factors, although these are not yet fully understood. The present research aimed to explore the DNA methylation patterns in whole blood of extrinsic apoptotic signalling pathway-related genes in AIT among areas with different iodine levels. We selected the iodine-fortification areas, iodine-adequate areas and water-based iodine-excess areas from Shandong Province of China as survey sites. Totally, 176 AIT cases and 176 controls were included. MethylTargetTM and QT-PCR technology were used to detect candidate genes’ DNA methylation levels and mRNA expression levels, respectively. We found that death associated protein kinase 1 (DAPK1) DNA methylation levels in AIT cases (especially in female) were significantly higher than controls (t = 2·7715, P = 0·0059; t = 2·4638, P = 0·0143 in female). There were differences in DAPK1 (t = 2·5384, P = 0·0121), TNF superfamily member 8 (t = 2·1667, P = 0·0334) and TNF-α-induced protein 8 (TNFAIP8) (t = 2·5672, P = 0·0121) genes methylation between cases and controls with different water iodine levels. The mRNA expression of DAPK1 (t = 4·329, P < 0·001) and TNFAIP8 (t = 3·775, P < 0·001) in the cases was increased. We identified the differences in the DNA methylation status of the extrinsic apoptotic signalling pathway-related genes between AIT and controls and in different iodine levels areas. The results were verified at the mRNA level. The environmental iodine may affect DNA methylation to some extent.