基于改进Black-Litterman模型的投资组合优化

考虑到金融市场“非完全有效性”且投资者“非完全理性”,通过贝叶斯框架建立了投资者观点与多渠道信息相结合的改进Black-Litterman模型,由此确定了最优的个性化投资策略.在中国股票市场的实证研究中,利用SVM-ARIMA-GARCH模型解决了投资者观点量化的问题.对比几类参考策略,改进Black-Litterman模型所确定的最优投资策略的样本外绩效表现更加稳健,在不同市场行情下均能获得较高的夏普比率和较低的换手率.

Vibration Reduction by a Partitioned Dynamic Vibration Absorber with Acoustic Black Hole Features

Vibration quality is a vital indicator for assessing the progress of modern equipment.The dynamic vibration absorber(DVA)based on the acoustic black hole(ABH)feature is a new passive control method that manipulates waves.It offers efficient energy focalization and broad-spectrum vibration suppression,making it highly promising for applications in large equipment such as aircraft,trains,and ships.Despite previous advancements in ABH-DVA development,certain challenges remain,particularly in ensuring effective coupling with host structures during control.To address these issues,this study proposes a partitioned ABH-featured dynamic vibration absorber(PABH-DVA)with partitions in the radial direction of the disc.By employing a plate as the host structure,simulations and experiments were conducted,demonstrating that the PABH-DVA outperforms the original symmetric ABH-DVA in terms of damping performance.The study also calculated and compared the coupling coefficients of the two ABH-DVAs to uncover the mechanism behind the enhanced damping.Simulation results revealed that the PABH-DVA exhibits more coupled modes,occasionally with lower coupling coefficients than the symmetric ABH-DVA.The influence of frequency ratio and modal mass was further analyzed to explain the reasons behind the PABH-DVA's superior damping performance.Additionally,the study discussed the impact of the number of slits and their orientation.This research further explains the coupling mechanism between the ABH-DVA and the controlled structure,and provides new ideas for the further application of ABH in engineering.

A progress review of black carbon deposition on Arctic snow and ice and its impact on climate change

The rapid warming of the Arctic,accompanied by glacier and sea ice melt,has significant consequences for the Earth’s climate,ecosystems,and economy.Black carbon(BC)deposition on snow and ice can trigger a significant reduction in snow albedo and accelerate melting of snow and ice in the Arctic.By reviewing the published literatures over the past decades,this work provides an overview of the progress in both the measurement and modeling of BC deposition and its impact on Arctic climate change.In summary,the maximum value of BC deposition appears in the western Russian Arctic(26 ng·g^(–1)),and the minimum value appears in Greenland(3 ng·g^(–1)).BC records in the Arctic ice core already peaked in 1920s and 1970s,and shows a regional difference between Greenland and Canadian Arctic.The different temporal variations of Arctic BC ice core records in different regions are closely related to the large variability of BC emissions and transportation processes across the Arctic region.Model simulations usually underestimate the concentration of BC in snow and ice by 2–3 times,and cannot accurately reflect the seasonal and regional changes in BC deposition.Wet deposition is the main removal mechanism of BC in the Arctic,and observations show different seasonal variations in BC wet deposition in Ny-Ålesund and Barrow.This discrepancy may result from varying contributions of anthropogenic and biomass burning(BB)emissions,given the strong influence by BC from BB emissions at Barrow.Arctic BC deposition significantly influences regional climate change in the Arctic,increasing fire activities in the Arctic have made BB source of Arctic BC more crucial.On average,BC in Arctic snow and ice causes an increase of+0.17 W·m^(–2)in radiative forcing and 8 Gt·a^(–1)in runoff in Greenland.As stressed in the latest Arctic Monitoring and Assessment Programme report,reliable source information and long-term and high-resolution observations on Arctic BC deposition will be crucial for a more comprehensive understanding and a better mitigation strategy of Arctic BC.In the future,it is necessary to collect more observations on BC deposition and the corresponding physical processes(e.g.,snow/ice melting,surface energy balance)in the Arctic to provide reliable data for understanding and clarifying the mechanism of the climatic impacts of BC deposition on Arctic snow and ice.

How is a black hole created from nothing?

Using the synchronous coordinates,the creation of a Schwarzschild black hole immersed in a de Sitter spacetime can be viewed as a coherent creation of a collection of timelike geodesics.The previously supposed conical singularities do not exist at the horizons of the constrained instanton.Instead,the unavoidable irregularity is presented as a nonvanishing second fundamental form elsewhere at the quantum transition 3-surface.The same arguments can be applied to charged,topological,or higher dimensional black hole cases.

Assessing the Efficacy of Lemongrass (Cymbopogon citratus) and Sambong (Blumea balsamifera) Extracts in Combating Black Pod Disease: Sustainable Solutions for Controlling Phytophthora megakarya in Cameroon’s Cocoa Plantations

The use of plant extracts as antifungal agents is gaining increasing attention, particularly for the control of black pod disease in cocoa. Despite extensive research, current strategies haven’t been entirely effective. This study evaluated the effectiveness of Cymbopogon citratus and Blumea balsamifora leaf extracts, both individually and in combination, against Phytophthora megakarya. We assessed the efficacy of the most promising combination (75% B. balsamifera, 25% C. citratus) after storage at room temperature for up to 9 days. Agar microdilution and in vivo bioassays were conducted to determine antifungal susceptibility and effectiveness. Blumea extract exhibited the highest overall inhibitory activity, with the lowest minimum inhibitory concentration (117 µl mL−1) while C. citratus had a narrower range of MIC (146 to 233 µl mL−1). The combination of C. citratus and B. balsamifera demonstrated a synergistic effect against P. megakarya, achieving growth inhibition on V8 media (92.72 ± 4.20% to 100%) and on artificially infected detached pod cortex (92.24 ± 4.53% to 98.75 ± 1.25%), which was not significantly different from the positive control (Ridomil). Furthermore, this combination maintained its effectiveness for up to 9 days at room temperature. These findings suggest that combining plant extracts can enhance their antifungal properties.

Black Garlic as an Antiviral for Herpes Simplex Virus-2 in Lung Cells

Allicin, an antioxidant, is known for providing garlic with its unique fragrance and taste, as well as for its antimicrobial properties. Black garlic, a fermented form of garlic, contains higher levels of antioxidants than fresh garlic. Antioxidants play a vital role in alleviating cellular stress during viral infections. Viral infections result in oxidative stress through the production of reactive oxidative species (ROS). A prolonged state of oxidative stress can result in cell death, DNA damage, and disease progression. In this study, black garlic extract (BGE) is evaluated for its ability to mitigate cytopathic effects and oxidative stress caused by herpes simplex virus-2 (HSV-2) infections in vitro. Antiviral assays were performed to determine the percent of viral inhibition resulting from treatment with the BGE. ROS-GloTM H2O2 assays were then completed to measure the post-infection ROS levels of BGE-treated virus and cells. The results thus far suggest that BGE may inhibit viral infection and decrease levels of oxidative stress.

Polyphenol components in black chokeberry(Aronia melanocarpa)as clinically proven diseases control factors——an overview

The black chokeberry is rich in polyphenols,including flavonoids with anthocyanins,flavanols and lavonols as the main components and a variety of phenolic acids represented by chlorogenic acid.Because of these polyphenols,black chokeberry has the effect of preventing and adjuvant therapy diseases.This study summarized the current research results on the types and contents of functional components in black chokeberry,and analyzed their digestion,absorption and metabolism in human body.On this basis,the disease control functions that have been proved effective in clinical research were reviewed and analyzed.These studies showed that black chokeberry have good prevention and adjuvant therapy effects on hyperlipidemia,hypertension,diabetes and inflammation.Because there are different functional components in black chokeberry,its prevention and treatment of the same disease can come from multiple pathways,which provides a more reliable effectiveness for the disease control of different populations.

Carbonic anhydrase 2 mediates anti-obesity effects of black tea as thermogenic activator

Obesity is a metabolic disorder due to over-accumulation of adipose tissue and ultimately becomes a“disease”.Brown adipose tissue(BAT)thermogenesis and white adipose tissue(WAT)browning emerge as a potential strategy of anti-obesity by dissipating energy as heat.However,drugs based on adipose tissue thermogenesis have not been successfully approved yet.In current study,we found that black tea extract(BTE)obtained by patentauthorized manufacturing process prevented body weight gain as novel thermogenic activator with reduction of adiposity,improvement of adipose distribution,and glucose metabolism improvement in diet-induced obesity mice.Mechanismly,anti-obesity effect of BTE depends on promoting BAT thermogenesis and WAT browning with upregulation of uncoupling protein 1(UCP1),especially visceral adipose tissue(VAT)with browning resistance.Specifically,utilizing in silico approach of network pharmacology and molecular docking,we identified carbonic anhydrase 2(CA2)in nitrogen metabolism as anti-obesity target of BTE and further elucidated that protein kinase B(AKT)signaling pathway linked CA2 and UCP1.Meanwhile gut microbiota regulation may prompt the CA2-dependent thermogenesis activation.Our findings demonstrated anti-obesity effect of BTE as thermogenic activator through CA2-mediated BAT thermogenesis and WAT browning via CA2-AKT-UCP1 signaling pathway,which could be developed as promising anti-obesity agent with good safety and efficacy.

View of thermodynamic phase transition of the charged Gauss-Bonnet AdS black hole via the shadow

We examine thermodynamic phase transition(PT)of the charged Gauss-Bonnet Ad S black hole(BH)by utilizing the shadow radius.In this system,we rescale the corresponding Gauss-Bonnet coefficientαby a factor of 1/(D-4),and ensure thatαis positive to avoid any singularity problems.The equation derived for the shadow radius indicates that it increases as the event horizon radius increases,making it an independent variable for determining BH temperature.By investigating the PT curve in relation to shadows,we can observe that the shadow radius can be used as an alternative to the event horizon radius in explaining the phenomenon of BH PT.Furthermore,the results indicate that an increase in the parameterαcorresponds to a decrease in the temperature of the BH.By utilizing the relationship between the temperature and the shadow radius,it is possible to obtain the thermal profile of the Gauss-Bonnet AdS BH.It is evident that there is an N-type variation in temperature for pressures P<P_(c).Additionally,as the parameterαincreases,the region covered by shadow expands while the temperature decreases.The utilization of BH shadows as a probe holds immense significance in gaining a deeper understanding of BH thermodynamic behavior.

A Novel Derivation of Black Hole Entropy in all Dimensions from Truly Point Mass Sources

It is explicitly shown how the Schwarzschild Black Hole Entropy (in all dimensions) emerges from truly point mass sources at r=0due to a non-vanishing scalar curvature involving the Dirac delta distribution. In order to achieve this, one is required to extend the domain of r to negative values −∞≤r≤+∞. It is the density and anisotropic pressure components associated with the point mass delta function source at the origin r=0which furnish the Schwarzschild black hole entropy in all dimensions D≥4after evaluating the Euclidean Einstein-Hilbert action. Two of the most salient results are i) that the observed spacetime dimension D=4is precisely singled out from all the other dimensions when the strong and weak energy conditions are met, and ii) the point mass source described in this work is not the result of a spherically symmetric gravitational collapse of a star as described by the Oppenheimer-Snyder model because we are not neglecting the pressure. As usual, it is required to take the inverse Hawking temperature βHas the length of the circle Sβ1obtained from a compactification of the Euclidean time in thermal field theory which results after a Wick rotation, it=τ, to imaginary time. This approach can be generalized to the Reissner-Nordstrom and Kerr-Newman metrics. The physical implications of this finding warrant further investigation since it suggests a profound connection between the notion of gravitational entropy and spacetime singularities.

Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian,SW China:Constraints from in situ LA-ICP-MS Analysis of Pyrite

A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite.The results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan profile.The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional environments.The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from seawater.Overall,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.

Triple points and phase transitions of D-dimensional dyonic Ad S black holes with quasitopological electromagnetism in Einstein–Gauss–Bonnet gravity

By considering the negative cosmological constant Λ as a thermodynamic pressure, we study the thermodynamics and phase transitions of the D-dimensional dyonic Ad S black holes(BHs) with quasitopological electromagnetism in Einstein–Gauss–Bonnet(EGB) gravity. The results indicate that the small/large BH phase transition that is similar to the van der Waals(vdW) liquid/gas phase transition always exists for any spacetime dimensions. Interestingly, we then find that this BH system exhibits a more complex phase structure in 6-dimensional case that is missed in other dimensions.Specifically, it shows for D = 6 that we observed the small/intermediate/large BH phase transitions in a specific parameter region with the triple point naturally appeared. Moreover, when the magnetic charge turned off, we still observed the small/intermediate/large BH phase transitions and triple point only in 6-dimensional spacetime, which is consistent with the previous results. However, for the dyonic Ad S BHs with quasitopological electromagnetism in Einstein–Born–Infeld(EBI) gravity, the novel phase structure composed of two separate coexistence curves observed by Li et al. [Phys. Rev. D105 104048(2022)] disappeared in EGB gravity. This implies that this novel phase structure is closely related to gravity theories, and seems to have nothing to do with the effect of quasitopological electromagnetism. In addition, it is also true that the critical exponents calculated near the critical points possess identical values as mean field theory. Finally, we conclude that these findings shall provide some deep insights into the intriguing thermodynamic properties of the dyonic Ad S BHs with quasitopological electromagnetism in EGB gravity.

Analysis of flavor and widely metabolomics differences in black sesame before and after processing

The objective of this study was to determine the differences of aroma and taste in three black sesame originsbefore and after processing via flavor and widely metabolomics.By analyzing the sensory characteristics and metabolites of raw and treated black sesame from China,Vietnam,and Myanmar,treated Chinese sesame have the most significant change in hardness after thermal processing,low viscosity and was easy to chew.The electronic nose could distinguish between raw and treated sesame due to the aroma distribution.The reason of treated sesame from China was“fragrant”is due to the highest content(2545.50μg/kg)of total pyrazines including 2,5-dimethylpyrazine,2-ethyl-5-methylpyrazine,2,3,5-trimethylpyrazine,3-ethyl-2,5-dimethylpyrazine.933 metabolites were detected via a wide targeted metabolomics in the taste of raw and treated sesame.Based on the analysis of metabolites related to bitterness,145 substances were selected.The main bitter contributors may be amino acids,dipeptides and organic acids.

Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal‑Lightweighted Water Electrolysis

The metal-lightweighted electrocatalysts for water splitting are highly desired for sustainable and economic hydrogen energy deployments,but challengeable.In this work,a low-content Ni-functionalized approach triggers the high capability of black phosphorene(BP)with hydrogen and oxygen evolution reaction(HER/OER)bifunctionality.Through a facile in situ electro-exfoliation route,the ionized Ni sites are covalently functionalized in BP nanosheets with electron redistribution and controllable metal contents.It is found that the as-fabricated Ni-BP electrocatalysts can drive the water splitting with much enhanced HER and OER activities.In 1.0 M KOH electrolyte,the optimized 1.5 wt%Nifunctionalized BP nanosheets have readily achieved low overpotentials of 136 mV for HER and 230 mV for OER at 10 mA cm^(−2).Moreover,the covalently bonding between Ni and P has also strengthened the catalytic stability of the Ni-functionalized BP electrocatalyst,stably delivering the overall water splitting for 50 h at 20 mA cm^(−2).Theoretical calculations have revealed that Ni–P covalent binding can regulate the electronic structure and optimize the reaction energy barrier to improve the catalytic activity effectively.This work confirms that Ni-functionalized BP is a suitable candidate for electrocatalytic overall water splitting,and provides effective strategies for constructing metal-lightweighted economic electrocatalysts.

Generalized Newton’s Theory of Universal Gravitation and Black Holes

The Newton’s theory of universal gravitation is generalized. Significantly strong at short distances central interaction of bodies and particles is established in comparison with Newtonian. A connection is found with Black Holes, with the horizon of events. Possibility of systematization of all Black Holes is shown. An illustration is given on the example of Black Hole SgrA*.

Charged Particles Capture Cross-section by a Weakly Charged Schwarzschild Black Hole

We study the capture cross-section of charged particles by a weakly charged Schwarzschild black hole.The dependence of the maximum impact parameter for capture on the particle’s energy is investigated numerically for different values of the electromagnetic coupling strength between the particle and the black hole.The capture cross-section is then calculated.We show that the capture cross-section is independent of the electromagnetic coupling for ultra-relativistic particles.The astrophysical implications of our results are discussed.

Thermodynamics in a quantum corrected Reissner-Nordstr?m-AdS black hole and its GUP-corrections

We calculate the thermodynamic quantities in the quantum corrected Reissner-Nordstr?m-AdS(RN-AdS)black hole,and examine their quantum corrections.By analyzing the mass and heat capacity,we give the critical state and the remnant state,respectively,and discuss their consistency.Then,we investigate the quantum tunneling from the event horizon of massless scalar particle by using the null geodesic method,and charged massive boson W^(±)and fermions by using the Hamilton-Jacob method.It is shown that the same Hawking temperature can be obtained from these tunneling processes of different particles and methods.Next,by using the generalized uncertainty principle(GUP),we study the quantum corrections to the tunneling and the temperature.Then the logarithmic correction to the black hole entropy is obtained.

Black radish root extract alleviates sodium valproate-induced liver damage via inhibiting mitochondrial membrane potential collapse and oxidative stress in mice

Objective:To explore the effect of black radish(Raphanus sativus L.var niger)root extract on liver enzymes,oxidative stress,and histopathological alterations in mice with sodium valproate-induced hepatotoxicity.Methods:Thirty-two mice were divided into four groups:the control group received drinking water by gavage,the second group was administered with 100 mg/kg of sodium valproate,the third group received 300 mg/kg of black radish root extract,and the fourth group was given both sodium valproate(100 mg/kg)and black radish root extract(300 mg/kg).After 28 days,the mice were euthanized,and serum levels of aspartate aminotransferase(AST),alanine aminotransferase(ALT),and alkaline phosphatase(ALP),along with liver malondialdehyde(MDA),reactive oxygen species(ROS),mitochondrial parameters,tumor necrosis factor-alpha(TNF-α)gene expression,and histopathological changes were assessed.Results:Sodium valproate caused hepatic damage in mice,characterized by elevated serum levels of liver enzymes,increased MDA and ROS levels and TNF-αgene expression,as well as histopathological alterations.The black radish root extract significantly alleviated sodium valproate-caused hepatic injury by decreasing the serum levels of ALT and AST,MDA,ROS,TNF-αgene expression,as well as mitochondrial impairment,but did not have a significant effect on sodium valproate-induced histopathological changes.Conclusions:The black radish root extract demonstrates protective effects against sodium valproate-induced liver injury,possibly through mitigating oxidative stress,mitochondrial impairment,and inflammatory mediator expression.

Timing and Spectral Analysis of the Black Hole X-Ray Binary MAXI J1803-298 with Insight-HXMT Data

We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft state.Within the Insight-HXMT data set,compared to the previous work,we identify a more prolonged presence of typeC quasi-periodic oscillations(QPOs)with centroid frequencies ranging from~0.16 to 6.3 Hz,which present correlations with the hardness ratio and the photon index of the Comptonized component.For QPO frequencies less than~2 Hz,the QPO phase lags are hard(photons of 10–19 keV arrive later than those of 1–4 keV),while at higher frequencies,the lags become soft at and above~4 Hz.Furthermore,the spectra in all Insight-HXMT observations consist of a multi-color blackbody component and a Comptonized component,as commonly observed in classical black hole X-ray binaries.We analyze state transitions and the evolution of accretion geometry in this work.The fitted inner disk radius increases abnormally during the low hard state,hypothesized to result from the corona condensing onto the inner disk.Additionally,two significant drops in flux are observed during the soft intermediate state,maybe implying changes in the corona/jet and the disk,respectively.

Thermodynamics of charged AdS black hole surrounded by quintessence in restricted phase space

We study thermodynamics of charged AdS black hole surrounded by quintessence in a new formalism which is called the restricted phase space thermodynamics.This context is based on Visser’s holographic thermodynamics with a fixed antide Sitter radius and a variable Newton constant.The conjugate variables,central charge C and the chemical potential m,are introduced as a new pair of thermodynamic variables.We find that the iso-e-charge T-S curve becomes non-monotonic when Q<Q_(c).Correspondingly,the F-T curve exhibits a swallow tail structure.This behavior is considered as a van der Waals-like phase transition.As the value of b related to the energy density of Kiselev’s fluid becomes larger,the critical temperature T_(c)will decrease.Thus,the van derWaals-like phase transition will occur at lower temperature.There is always a non-quilibrium transition from a small unstable black hole to a large stable black hole state in the isocoltage T-S process.There exist a maximum and a Hawking-Page phase transition points in theμ-C plane.As the value of b related to Kiselev’s fluid becomes larger,the Hawking-Page phase transition will occur at lower temperature in the isovoltageμ-T process.For other values of the state parameterω,there also exists van der Waals-like phase transition.