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Background: With the rapid growth of healthcare services, health insurance fraud detection has become an important measure to ensure efficient use of public funds. Traditional fraud detection methods have tended to focus on the attributes of a single visit and have ignored the behavioural relationships of multiple visits by patients. Methods: We propose a health insurance fraud detection model based on a multilevel attention mechanism that we call MHAMFD. Specifically, we use an attributed heterogeneous information network (AHIN) to model different types of objects and their rich attributes and interactions in a healthcare scenario. MHAMFD selects appropriate neighbour nodes based on the behavioural relationships at different levels of a patient's visit. We also designed a hierarchical attention mechanism to aggregate complex semantic information from the interweaving of different levels of behavioural relationships of patients. This increases the feature representation of objects and makes the model interpretable by identifying the main factors of fraud. Results: Experimental results using real datasets showed that MHAMFD detected health insurance fraud with better accuracy than existing methods. Conclusions: Experiment suggests that the behavioral relationships between patients' multiple visits can also be of great help to detect health care fraud. Subsequent research fraud detection methods can also take into account the different behavioral relationships between patients. [ABSTRACT FROM AUTHOR]

• Fully resolved simulations of fluid-particle systems. • Surface reaction with significant heat effects. • Temperature-dependent reaction rates determined by the Arrhenius equation. • Simulation parameters adopted from realistic POX reaction. In this paper, an efficient ghost-cell based immersed boundary method (IBM) is used to perform direct numerical simulation (DNS) of reactive fluid-particle systems. With an exothermic first order reaction proceeding at the exterior particle surface, the solid temperature rises and consequently increases the reaction rate via an Arrhenius temperature dependence. In other words, the heat and mass transport is dependently coupled through the particle thermal energy equation and the Arrhenius equation, and they offer dynamic boundary conditions for the fluid phase thermal energy equation and species equation respectively. The fluid-solid coupling is enforced at the exact position of the particle surface by implicit incorporation of the boundary conditions into the discretized momentum, species and thermal energy conservation equations of the fluid phase. Different fluid-particle systems are studied with increasing complexity: a single sphere, three spheres and a dense array consisting of hundreds of randomly generated particles. In these systems the mutual impacts between heat and mass transport processes are investigated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fully resolved simulations of heat transfer problems in tubular fluid-particle systems. • Handles mixed boundary conditions, i.e. isothermal and isoflux, consistently. • Investigation of the influence of particle sizes and passive particles. • Comparison between two classes of immersed boundary method, i.e. CFM and DFM. Abstract In this paper two immersed boundary methods (IBM), specifically a continuous forcing method (CFM) and a discrete forcing method (DFM), are applied to perform direct numerical simulations (DNSs) of heat transfer problems in tubular fluid-particle systems. Both IBM models are built on the well-developed models utilized in momentum transfer studies, and have the capability to handle mixed boundary conditions at the particle surface as encountered in industrial applications with both active and passive particles. Following a thorough verification of both models for the classical Graetz-Nusselt problem, we subsequently apply them to study a much more advanced Graetz-Nusselt problem of more practical importance with a dense stationary array consisting of hundreds of particles randomly positioned inside a tube with adiabatic wall. The influence of particle sizes and fractional amount of passive particles is analyzed at varying Reynolds numbers, and the simulation results are compared between the two IBM models, finding good agreement. Our results thus qualify the two employed IBM modules for more complex applications. [ABSTRACT FROM AUTHOR]

In this paper, an efficient ghost-cell based immersed boundary method is introduced to perform direct numerical simulation (DNS) of mass transfer problems in particulate flows. The fluid-solid coupling is achieved by implicit incorporation of the boundary conditions into the discretized momentum and species conservation equations of the fluid phase. Taking the advantage of a second order quadratic interpolation scheme utilized in the reconstruction procedures, the unique feature of this ghost-cell based immersed boundary method is its capability to handle mixed boundary conditions at the exact position of the particle surface as encountered in systems with interplay between surface reactions and diffusion. A fixed Eulerian grid is used to solve the conservation equations for the entire computational domain. Following a detailed verification of the method in the limiting case of unsteady molecular diffusion without convection, we apply our method to study fluid-particle mass transfer for flow around a single sphere and a dense stationary array consisting of hundreds of spheres over a range of Damköhler numbers. [ABSTRACT FROM AUTHOR]

Background: Telomeres consist of repetitive DNA sequences at the chromosome ends to protect chromosomal stability, and primarily maintained by telomerase or occasionally by alternative telomere lengthening of telomeres (ALT) through recombination-based mechanisms. Additional mechanisms that may regulate telomere maintenance remain to be explored. Simultaneous measurement of telomere length and transcriptome in the same human embryonic stem cell (hESC) revealed that mRNA expression levels of UBQLN1 exhibit linear relationship with telomere length. Methods: In this study, we first generated UBQLN1-deficient hESCs and compared with the wild-type (WT) hESCs the telomere length and molecular change at RNA and protein level by RNA-seq and proteomics. Then we identified the potential interacting proteins with UBQLN1 using immunoprecipitation-mass spectrometry (IP-MS). Furthermore, the potential mechanisms underlying the shortened telomeres in UBQLN1-deficient hESCs were analyzed. Results: We show that Ubiquilin1 (UBQLN1) is critical for telomere maintenance in human embryonic stem cells (hESCs) via promoting mitochondrial function. UBQLN1 deficiency leads to oxidative stress, loss of proteostasis, mitochondria dysfunction, DNA damage, and telomere attrition. Reducing oxidative damage and promoting mitochondria function by culture under hypoxia condition or supplementation with N-acetylcysteine partly attenuate the telomere attrition induced by UBQLN1 deficiency. Moreover, UBQLN1 deficiency/telomere shortening downregulates genes for neuro-ectoderm lineage differentiation. Conclusions: Altogether, UBQLN1 functions to scavenge ubiquitinated proteins, preventing their overloading mitochondria and elevated mitophagy. UBQLN1 maintains mitochondria and telomeres by regulating proteostasis and plays critical role in neuro-ectoderm differentiation. [ABSTRACT FROM AUTHOR]

Pancake bouncing of water droplets on superhydrophobic surfaces has been extensively studied, because the reduction in solid–liquid contact time shows great potential for self-cleaning, anti-icing, etc. However, the behavior of a pancake-bouncing droplet in the ambient air and its subsequent interaction with the underlying surface remain unrevealed, which is actually crucial for practical applications. In this Letter, we comprehensively investigate the overall dynamics of droplets on post-array superhydrophobic surfaces by extending the range of impact velocities. An unreported phenomenon was observed, whereby the retracting droplet undergoes vertical elongation and re-contacts the underlying surface following the pancake bouncing event. As the impact velocity increases, the submillimeter-scale posts notably influence the droplet splash, where tiny droplets are ejected from the edges of lateral liquid jets through the posts. Experimental results and scale analysis show that the critical Weber number for this jet splash phenomenon decreases with the post spacing and the post edge length over a certain range. The violent jet splash occurring at higher Weber numbers reduces the mass of the remaining droplet and, consequently, diminishes the diameter prior to retraction, thereby suppressing the secondary contact with the surface. Our findings are believed to provide valuable insight for the understanding and the application of the pancake bouncing effect. [ABSTRACT FROM AUTHOR]

Salvianolic acid B (Sal B) has previously reported anti-hepatic fibrosis effects, though it is not clear if it can inhibit hepatic fibrosis by regulating the hedgehog (Hh) signaling pathway. The aim of the present study was to explore the roles and mechanism of Sal B in preventing and treating liver fibrosis in rats. The study also aimed to determine the role of the Hh signaling pathway in this process. A rat model of liver fibrosis was induced through the subcutaneous injection of 50% carbon tetrachloride, followed by treatment with Sal B. After gavage, blood was collected to detect serum markers of liver injury. The degree of liver fibrosis and tissue damage was assessed using histopathological analysis. Western blotting and reverse transcription-quantitative PCR were used to detect the expression levels of TGF-β1 and Hh signaling pathway-related genes, including Sonic hedgehog (Shh) protein, membrane protein receptor protein patched homolog 1 (Ptch1), membrane protein receptor Smoothened (Smo) and transcription factor glioma-associated oncogene homolog 1 (Gli1). Serum alanine aminotransferase, aspartate aminotransferase and total bilirubin levels were decreased, whilst levels of albumin were increased in rats with liver fibrosis that were treated with Sal B (P<0.05). Additionally, significant increases in TGF-β1, Shh, Ptch1, Smo, Gli1 and α-smooth muscle actin expression levels were observed in the liver tissues of rats with hepatic fibrosis (P<0.05). However, Sal B treatment significantly reduced the expression levels of these proteins (P<0.05). In conclusion, the results of the present study suggested that the Hh signaling pathway may be activated during the process of rat liver fibrosis. Thus, Sal B may exert its anti-hepatic fibrosis effects, at least in part, by inhibiting the activation of the Hh signaling pathway. [ABSTRACT FROM AUTHOR]