•In this paper, we examine whether gold or Bitcoin is a safe haven against economic policy uncertainty (EPU).•We combine the GARCH model and quantile regression with dummy variables, which include ...the extreme situations of average condition and different quantiles.•Hedge and safe-haven roles of gold and Bitcoin against EPU shocks are correlated with their bearish or bullish market situation.•Bitcoin reacts more responsive to EPU shocks and gold maintains stability with smaller hedge and safe-haven coefficients.
Calculating the hedge and safe-haven properties of gold and Bitcoin via GARCH model and quantile regression with dummy variables. We find that: (1) Neither gold nor Bitcoin can serve as a strong hedge or safe-haven for economic policy uncertainty (EPU) at the average condition. (2) Bitcoin is more responsive to EPU shocks, while gold maintains stability with smaller hedge and safe-haven coefficients. (3) In most cases, both gold and Bitcoin can act as the weak hedge and weak safe-haven against EPU during the extreme bearish and bullish markets, which two can be considered for portfolio diversification during the normal market.
The dreamlet (drumbeat-beamlet) transform can provide us an efficient method to represent physical wavefield, because the dreamlet basis satisfies automatically the wave equation, which is a ...distinctive feature different from mathematical basis, such as Fourier and curvelet. It can obtain an estimation of true signal from the observed noisy data by abandoning those insignificant components in the dreamlet domain. However, we have found that a more accurate estimation can be achieved by a damped version of the dreamlet representation. We have theoretically derived the damped dreamlet representation and given its geometric interpretation and analysis. Two applications of the proposed method have been explored in this paper: seismic random noise suppression and seismic data interpolation. Various examples demonstrate that the damped dreamlet representation-based technique has a superior performance compared with the mathematical-basis-based representation and rank-reduction-based techniques.
Summary
Douchi are good food for obesity prevention, but limited information is known about the potential relationship between hyperlipidaemic effect and intestinal microbiological regulation of ...Douci. To explore the hyperlipidaemic effect of Douchi fermented by Rhizopus chinensis 12 on hyperlipidaemia rats and the correlation between intestinal flora and hyperlipidaemic effect. The intervention with Douchi significantly (P < 0.05) reduced the levels of total cholesterol, total triglyceride and low‐density lipoprotein cholesterol, increased the level of high‐density lipoprotein cholesterol, and improved liver damage and fat cell hypertrophy caused by high‐fat diet. Douchi also increased the anti‐ atherosclerosis index and reduced the levels of human oxidized low‐density lipoprotein, tumour necrosis factor‐α, monocyte chemotactic protein‐1, C‐reactive protein, interleukin‐6 and interleukin‐1β. Furthermore, Douchi regulated the expression of key proteins and significantly (P < 0.05) reversed the decrease in the richness and diversity of the gut microbiota caused by high‐fat feeding. The correlation analysis revealed that the relative abundance of Romboutsia was positively correlated with four lipids and inflammatory factors, while that of Lactobacillus, Allobaculum, unidentified_Corynebacterium, Aerococcus, Facklamia, Alcaligenes and unidentified_Clostridiales was negatively correlated. Douchi modulated the activate lipid metabolism and reduced the level of serum inflammatory factors by regulating the balance of the gut microbiota to achieve the anti‐hyperlipidaemic effect.
Purpose
To evaluate the effect of soft contact lens with concentric ring bifocal and peripheral add multifocal designs on controlling myopia progression in school‐aged children.
Methods
We ...systematically searched MEDLINE, EMBASE, Cochrane Library and reference lists of included trials. Methodological quality of included trials was assessed using Jadad Scale and Newcastle‐Ottawa Quality Assessment Scale items.
Results
We identified five randomised controlled trials (RCTs) and three cohort studies with a total of 587 myopic children. Compared with the control group, concentric ring bifocal soft contact lenses showed less myopia progression with a weighted mean difference (WMD) of 0.31 D (95% CI, 0.05~0.57 D, p = 0.02) and less axial elongation with a WMD of −0.12 mm (95% CI, approximately −0.18 to −0.07 mm, p < 0.0001) at 12 months. Relative to the control group, peripheral add multifocal soft contact lenses showed less myopia progression with a WMD of 0.22 D (95% CI 0.14~0.31 D, p < 0.0001) and less axial elongation of −0.10 mm (95% CI −0.13~0.07 mm, p < 0.0001) at 12 months, respectively. The soft contact lenses with concentric ring bifocal and peripheral add multifocal designs produced additional myopia control rates of 30~38% for slowing myopia progression and 31~51% for lessening axial elongation within 24 months.
Conclusions
Both concentric ring bifocal and peripheral add multifocal soft contact lenses are clinically effective for controlling myopia in school‐aged children, with an overall myopia control rates of 30~50% over 2 years. Concentric ring bifocal soft contact lenses seem to have greater effect than peripheral add multifocal soft contact lenses.
Full waveform inversion (FWI) is a powerful tool to understand the real complicated earth model. As FWI is a highly nonlinear problem and depends strongly on the initial model, how to effectively ...retrieve the large-scale background model is critical for the success of FWI. For elastic FWI (EFWI), the inversion challenge increases because the P-wave and S-wave are coupled together if no mode separation technologies are applied. In this article, we develop a new EFWI strategy, where we simultaneously implement the angle decomposition and mode separation for the wavefield. Based on the analysis of radiation patterns of different parameters and the fact that small scattering angles correspond to large-scale model perturbations, we can retrieve the large-scale background model of the P-wave velocity with pure small scattering angle P-P mode wavefield. On the other hand, the pure small scattering angle S-S, S-P, and P-S mode wavefields are used to estimate the large-scale background model of the S-wave velocity. The correctly retrieved large-scale background models further guarantee the success of subsequent fine structure retrieving for the P- and S-wave velocity models by using different wave modes. The proposed method is able to reduce the cycle-skipping problem and the multiparameter crosstalk problem simultaneously. Numerical examples show that the proposed method provides much improved inversion results than the conventional EFWI, which demonstrates the validity of the proposed method.
Porous materials have been widely used in batteries and supercapacitors attribute to their large internal surface area (usually 100–1000m2g−1) and porosity that can favor the electrochemical ...reaction, interfacial charge transport, and provide short diffusion paths for ions. As a new type of porous crystalline materials, metal-organic frameworks (MOFs) have received huge attention in the past decade due to their unique properties, i.e. huge surface area (up to 7000m2g−1), high porosity, low density, controllable structure and tunable pore size. A wide range of applications including gas separation, storage, catalysis, and drug delivery benefit from the recent fast development of MOFs. However, their potential in electrochemical energy storage has not been fully revealed. Herein, the present mini review appraises recent and significant development of MOFs and MOF-derived materials for rechargeable lithium ion batteries and supercapacitors, to give a glimpse into these potential applications of MOFs.
MOFs with large surface area and high porosity can offer more reaction sites and charge carriers diffusion path. Thus MOFs are used as cathode, anode, electrolyte, matrix and precursor materials for lithium ion battery, and also as electrode and precursor materials for supercapacitors. Display omitted
•MOFs have potential in electrochemical area due to their high porosity and diversity.•We summarized and compared works on MOFs for lithium ion battery and supercapacitor.•We pointed out critical challenges and provided possible solutions for future study.
A facile and scalable in situ synthesis strategy is developed to fabricate carbon-encapsulated Fe3O4 nanoparticles homogeneously embedded in two-dimensional (2D) porous graphitic carbon nanosheets ...(Fe3O4@C@PGC nanosheets) as a durable high-rate lithium ion battery anode material. With assistance of the surface of NaCl particles, 2D Fe@C@PGC nanosheets can be in situ synthesized by using the Fe(NO3)3·9H2O and C6H12O6 as the metal and carbon precursor, respectively. After annealing under air, the Fe@C@PGC nanosheets can be converted to Fe3O4@C@PGC nanosheets, in which Fe3O4 nanoparticles (∼18.2 nm) coated with conformal and thin onion-like carbon shells are homogeneously embedded in 2D high-conducting carbon nanosheets with a thickness of less than 30 nm. In the constructed architecture, the thin carbon shells can avoid the direct exposure of encapsulated Fe3O4 to the electrolyte and preserve the structural and interfacial stabilization of Fe3O4 nanoparticles. Meanwhile, the flexible and conductive PGC nanosheets can accommodate the mechanical stress induced by the volume change of embedded Fe3O4@C nanoparticles as well as inhibit the aggregation of Fe3O4 nanoparticles and thus maintain the structural and electrical integrity of the Fe3O4@C@PGC electrode during the lithiation/delithiation processes. As a result, this Fe3O4@C@PGC electrode exhibits superhigh rate capability (858, 587, and 311 mAh/g at 5, 10, and 20 C, respectively, 1 C = 1 A/g) and extremely excellent cycling performance at high rates (only 3.47% capacity loss after 350 cycles at a high rate of 10 C), which is the best one ever reported for an Fe3O4-based electrode including various nanostructured Fe3O4 anode materials, composite electrodes, etc.
Onion(Allium cepa L.) is a very important vegetable crop widely cultivated throughout the world. In this study, we measured total anthocyanins and flavonols of onions of three colors. The fresh ...weight(FW) of total anthocyanins were(29.99±1.19),(9.64±1.30) and(0.75±0.40) mg 100 g^–1 fruit in red, yellow and white onions, respectively. Likewise, the FW of total flavonoids were(111.10±5.98),(36.64±3.59), and 0 mg 100 g^–1 in red, yellow and white, respectively. Four types of anthocyanins(delphinidin 3,5-diglycosides, cyanidin 3,5-diglycosides, cyanidin 3-glycosides and cyanidin 3-(6′′-malonyl)-glucopyranoside) and two kinds of flavonoids(quercetin and quercetin 3-glycosides) were identified in two varieties(red and yellow bulb) of onions by HPLC/DAD-ESI/MS. The total polyphenol contents were also measured by means of Folin-Ciocalteu method. Moreover, all the concentrations of anthocyanins, flavonoids and polyphenols showed significantly positive correlations with antioxidant activities measured by DPPH˙, ABTS˙+ and FRAP assays. This study provided information on anthocyanin and flavonoids compositions that will be useful for onion breeding.