With wide applications, the smoothed particle hydrodynamics method (abbreviated as SPH) has become an important numerical tool for solving complex flows, in particular those with a rapidly moving ...free surface. For such problems, the incompressible Smoothed Particle Hydrodynamics (ISPH) has been shown to yield better and more stable pressure time histories than the traditional SPH by many papers in literature. However, the existing ISPH method directly approximates the second order derivatives of the functions to be solved by using the Poisson equation. The order of accuracy of the method becomes low, especially when particles are distributed in a disorderly manner, which generally happens for modelling violent water waves. This paper introduces a new formulation using the Rankine source solution. In the new approach to the ISPH, the Poisson equation is first transformed into another form that does not include any derivative of the functions to be solved, and as a result, does not need to numerically approximate derivatives. The advantage of the new approach without need of numerical approximation of derivatives is obvious, potentially leading to a more robust numerical method. The newly formulated method is tested by simulating various water waves, and its convergent behaviours are numerically studied in this paper. Its results are compared with experimental data in some cases and reasonably good agreement is achieved. More importantly, numerical results clearly show that the newly developed method does need less number of particles and so less computational costs to achieve the similar level of accuracy, or to produce more accurate results with the same number of particles compared with the traditional SPH and existing ISPH when it is applied to modelling water waves.
ABSTRACT
We investigate a correlation between the dark matter content of elliptical galaxies and their ellipticity ϵ that was initially reported in 2014. We use new determinations of dark matter and ...ellipticities that are posterior to that time. Our data set consists of 237 elliptical galaxies passing a strict set of criteria that selects a homogeneous sample of typical elliptical galaxies. We find a relation between the mass-to-light ratio and ellipticity ϵ that is well fitted by M/L = (14.1 ± 5.4)ϵ, which agrees with the result reported in 2014. Our analysis includes 135 galaxies that were not in the 2014 analysis, and includes data sets with refined versions of previous methods. The consistency between the present and 2014 analyses reduces the possibility that the initial observation of the correlation came from approximations in the methods used to estimate dark matter content or lower resolution data, thereby lending support to a physical origin.
Dental caries is closely associated with the microbial disequilibrium between acidogenic/aciduric pathogens and alkali-generating commensal residents within the dental plaque. Fluoride is a widely ...used anticaries agent, which promotes tooth hard-tissue remineralization and suppresses bacterial activities. Recent clinical trials have shown that oral hygiene products containing both fluoride and arginine possess a greater anticaries effect compared with those containing fluoride alone, indicating synergy between fluoride and arginine in caries management. Here, we hypothesize that arginine may augment the ecological benefit of fluoride by enriching alkali-generating bacteria in the plaque biofilm and thus synergizes with fluoride in controlling dental caries. Specifically, we assessed the combinatory effects of NaF/arginine on planktonic and biofilm cultures of Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis with checkerboard microdilution assays. The optimal NaF/arginine combinations were selected, and their combinatory effects on microbial composition were further examined in single-, dual-, and 3-species biofilm using bacterial species–specific fluorescence in situ hybridization and quantitative polymerase chain reaction. We found that arginine synergized with fluoride in suppressing acidogenic S. mutans in both planktonic and biofilm cultures. In addition, the NaF/arginine combination synergistically reduced S. mutans but enriched S. sanguinis within the multispecies biofilms. More importantly, the optimal combination of NaF/arginine maintained a “streptococcal pressure” against the potential growth of oral anaerobe P. gingivalis within the alkalized biofilm. Taken together, we conclude that the combinatory application of fluoride and arginine has a potential synergistic effect in maintaining a healthy oral microbial equilibrium and thus represents a promising ecological approach to caries management.
As the world's most populous country with the largest aging population and a rapidly growing economy, China is receiving increased attention from both the Chinese government and the governments of ...other countries that face low fertility and aging problems. This unprecedented shift of demographic structure has repercussions for many aspects of development including economic growth, social welfare, elder care, and other public welfare issues in China. Balancing population aging and economic growth requires innovative strategies and represents both challenges and opportunities for China.
Insulin resistance is one of the critical pathogeneses of type 2 diabetes mellitus (T2DM). Elevated levels of plasma branched-chain amino acids (BCAAs) are associated with insulin resistance. Recent ...studies have demonstrated the role of Porphyromonas gingivalis in the development of insulin resistance. However, the mechanisms by which P. gingivalis induces insulin resistance are still unclear. The purpose of this study was to investigate whether P. gingivalis induces insulin resistance through BCAA biosynthesis. We established a murine model of periodontitis by infecting mice with P. gingivalis. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs were measured. A P. gingivalis BCAA aminotransferase-deficient strain (∆bcat) was constructed, and its kinetic growth, biofilm formation, and in vivo colonization were compared with its wild-type strain. Alveolar bone loss, insulin sensitivity, and the plasma level of BCAAs of the mice infected with either wild-type strain or ∆bcat strain were further measured. We found that periodontal infection with P. gingivalis significantly upregulated the plasma level of BCAAs and aggravated the high-fat diet (HFD)–induced insulin resistance. Bcat deletion did not alter the growth, biofilm formation, and in vivo colonization of P. gingivalis. More important, the ∆bcat strain was unable to upregulate the plasma level of BCAAs and induce insulin resistance in HFD-fed mice. These findings suggest that the BCAA biosynthesis of P. gingivalis plays a critical role in the development of insulin resistance in the HFD-fed mice. The BCAA biosynthesis pathways may provide a potential target for the disruption of linkage between periodontitis and T2DM.
Over 100 trigonometric parallaxes and proper motions for masers associated with young, high-mass stars have been measured with the Bar and Spiral Structure Legacy Survey, a Very Long Baseline Array ...key science project, the European VLBI Network, and the Japanese VLBI Exploration of Radio Astrometry project. These measurements provide strong evidence for the existence of spiral arms in the MilkyWay, accurately locatingmany arm segments and yielding spiral pitch angles ranging from about 7degrees to 20degrees. Assuming a "universal" spiral galaxy form for the rotation curve, we estimate the thin disk scale length to be 2.44 + or - 0.16 kpc. With this large data set, the parameters R sub(0) and Theta sub(0) are no longer highly correlated and are relatively insensitive to different forms of the rotation curve.
During Treponema pallidum (T. pallidum) infection, the host's immune system actively engages in pursuit and elimination of T. pallidum, while T. pallidum skillfully employs various mechanisms to ...evade immune recognition. Macrophages exhibit incomplete clearance of T. pallidum in vitro and the underlying mechanism of how T. pallidum resists the attack of macrophage remains unclear.
To investigate the effect of T. pallidum membrane protein Tp47 on the phagocytosis of macrophages.
THP-1-derived macrophages were used to investigate the role of Tp47 in the secretion of Prostaglandin E2 (PGE2) in macrophages and the mechanism by which Tp47 induced the production of PGE2, as well as the impact of PGE2 on the macrophage's phagocytosis.
Tp47 (1-10 μg/mL) significantly inhibited the phagocytosis of latex beads and T. pallidum in macrophages (p ≤ 0.05). PGE2 production by macrophages could be induced by Tp47, and the phagocytic function of macrophages could be restored using PGE2 antibody. Tp47 produced PGE2 by activating the PERK/NF-κB/COX-2 pathway in macrophages. Inhibitors targeting PERK, NF-κB and COX-2, respectively, reduced the level of PGE2 and restored the phagocytic function of macrophages.
Tp47-induced PGE2 production via the PERK/NF-κB/COX-2 pathway contributed to macrophage phagocytosis inhibition, which potentially contributes to immune evasion during the T. pallidum infection.
There is currently limited data on which drug should be used to improve blood pressure (BP) control in patients with resistant hypertension (RH). We performed a systematic review and meta-analysis of ...published studies evaluating the anti-hypertensive benefit of aldosterone antagonists (AA) as an add-on therapy in patients with RH. A systematic literature search for eligible studies was conducted until June 2014, using literature databases and hand search. Studies were stratified according to controlled vs uncontrolled design and analyzed using random-effect models. We identified 13 eligible studies involving a total of 2640 patients, consisting of 3 randomized controlled trials, and 10 observational studies without a control group. In controlled studies, there was a reduction in mean systolic and diastolic BP of -16.5 (95% confidence interval (CI), -30.0 to -3.0) and -4.1 (95% CI, -7.8 to -0.32) mm Hg, respectively, compared with control. In uncontrolled studies, there was a reduction in mean systolic and diastolic BP of -19.7 (95% CI, -23.2 to -16.2) and -9.1 (95% CI, -10.3 to -7.8) mm Hg, respectively, compared with pre-AA therapy. Subgroup analysis showed that the systolic BP change was more pronounced in patients with baseline systolic BP >150 mm Hg (weighted mean difference (WMD), -23.1 mm Hg) than in patients with ⩽150 mm Hg (WMD, -15.4 mm Hg) (between groups P<0.001), suggesting that the baseline systolic BP was a predictor of the BP response to AA treatment. Furthermore, AA demonstrated a mild increase in serum potassium and creatinine (for both, P<0.001). The findings suggest that AA as an add-on therapy was effective for lowering systolic and diastolic BP in patients with RH.
The importance of the spin-orbit coupling (SOC) effect in Fe-based superconductors (FeSCs) has recently been under hot debate. Considering the Hund’s coupling-induced electronic correlation, the ...understanding of the role of SOC in FeSCs is not trivial and is still elusive. Here, through a comprehensive study ofSe77andFe57nuclear magnetic resonance, a nontrivial SOC effect is revealed in the nematic state of FeSe. First, the orbital-dependent spin susceptibility, determined by the anisotropy of theFe57Knight shift, indicates a predominant role from the3dxyorbital, which suggests the coexistence of local and itinerant spin degrees of freedom in the FeSe. Then, we reconfirm that the orbital reconstruction below the nematic transition temperature (Tnem∼90K) happens not only on the3dxzand3dyzorbitals but also on the3dxyorbital, which is beyond a trivial ferro-orbital order picture. Moreover, our results also indicate the development of a coherent coupling between the local and itinerant spin degrees of freedom belowTnem, which is ascribed to a Hund’s coupling-induced electronic crossover on the3dxyorbital. Finally, because of a nontrivial SOC effect, sizable in-plane anisotropy of the spin susceptibility emerges in the nematic state, suggesting a spin-orbital-intertwined nematicity rather than a simple spin- or orbital-driven nematicity. The present work not only reveals a nontrivial SOC effect in the nematic state but also sheds light on the mechanism of nematic transition in FeSe.
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