Modeling implied volatility(IV)is important for option pricing,hedging,and risk management.Previous studies of deterministic implied volatility functions(DIVFs)propose two parameters,moneyness and time to maturity,to ...Modeling implied volatility(IV)is important for option pricing,hedging,and risk management.Previous studies of deterministic implied volatility functions(DIVFs)propose two parameters,moneyness and time to maturity,to estimate implied volatility.Recent DIVF models have included factors such as a moving average ratio and relative bid-ask spread but fail to enhance modeling accuracy.The current study offers a generalized DIVF model by including a momentum indicator for the underlying asset using a relative strength index(RSI)covering multiple time resolutions as a factor,as momentum is often used by investors and speculators in their trading decisions,and in contrast to volatility,RSI can distinguish between bull and bear markets.To the best of our knowledge,prior studies have not included RSI as a predictive factor in modeling IV.Instead of using a simple linear regression as in previous studies,we use a machine learning regression algorithm,namely random forest,to model a nonlinear IV.Previous studies apply DVIF modeling to options on traditional financial assets,such as stock and foreign exchange markets.Here,we study options on the largest cryptocurrency,Bitcoin,which poses greater modeling challenges due to its extreme volatility and the fact that it is not as well studied as traditional financial assets.Recent Bitcoin option chain data were collected from a leading cryptocurrency option exchange over a four-month period for model development and validation.Our dataset includes short-maturity options with expiry in less than six days,as well as a full range of moneyness,both of which are often excluded in existing studies as prices for options with these characteristics are often highly volatile and pose challenges to model building.Our in-sample and out-sample results indicate that including our proposed momentum indicator significantly enhances the model’s accuracy in pricing options.The nonlinear machine learning random forest algorithm also performed better than a simple linear regression.Compared to prevailing option pricing models that employ stochastic variables,our DIVF model does not include stochastic factors but exhibits reasonably good performance.It is also easy to compute due to the availability of real-time RSIs.Our findings indicate our enhanced DIVF model offers significant improvements and may be an excellent alternative to existing option pricing models that are primarily stochastic in nature.展开更多
Using support vector regression （SVR）, a novel non-parametric method for recovering implied risk-neutral probability density function （IRNPDF） is investigated by solving linear operator equations. First, the SVR p...Using support vector regression （SVR）, a novel non-parametric method for recovering implied risk-neutral probability density function （IRNPDF） is investigated by solving linear operator equations. First, the SVR principle for function approximation is introduced, and an SVR method for solving linear operator equations with knowing some values of the right-hand function and without knowing its form is depicted. Then, the principle for solving the IRNPDF based on SVR and the method for constructing cross-kernel functions are proposed. Finally, an empirical example is given to verify the validity of the method. The results show that the proposed method can overcome the shortcomings of the traditional parametric methods, which have strict restrictions on the option exercise price; meanwhile, it requires less data than other non-parametric methods, and it is a promising method for the recover of IRNPDF.展开更多
This paper deals with options on assets, such as stocks or indexes, which pay cash dividends. Pricing methods which consider discrete dividends are usually computationally expensive and become infeasible when one cons...This paper deals with options on assets, such as stocks or indexes, which pay cash dividends. Pricing methods which consider discrete dividends are usually computationally expensive and become infeasible when one considers multiple dividends paid during the option lifetime. This is the case of long-term options and options on indexes. The first purpose of this paper is to assess efficient and accurate numerical procedures which yield consistent prices for both European and American options when the underlying asset pays discrete dividends. The authors then analyze some methodologies to extract information on implied volatilities and dividends from quoted option prices. Implied dividends can also be computed using a modified version of the well-known put-call parity relationship. This technique is straightforward, nevertheless, its use is limited to European options, and when dealing with equities, most traded options are of American type. As an alternative, the numerical inversion of pricing methods, such as efficient interpolated binomial method, can be used. This paper applies different procedures to obtain implied volatilities and dividends of listed stocks of the Italian derivatives market （IDEM）.展开更多
This paper concerns an inverse problem of recovering implied volatility in short-term interest rate model from the market prices of zero-coupon bonds. Based on lineariza-tion, an analytic solution, which is given as a...This paper concerns an inverse problem of recovering implied volatility in short-term interest rate model from the market prices of zero-coupon bonds. Based on lineariza-tion, an analytic solution, which is given as a power series, is derived for the direct problem.By neglecting high order terms in the power series, an integral equation about the pertur-bation of volatility is formulated and the Tikhonov regularization method is applied to solvethe integral equation. Finally numerical experiments are given and the results show that the method is effective.展开更多
The recently developed Bitcoin futures and options contracts in cryptocurrency derivatives exchanges mark the beginning of a new era in Bitcoin price risk hedging.The need for these tools dates back to the market cras...The recently developed Bitcoin futures and options contracts in cryptocurrency derivatives exchanges mark the beginning of a new era in Bitcoin price risk hedging.The need for these tools dates back to the market crash of 1987,when investors needed better ways to protect their portfolios through option insurance.These tools provide greater flexibility to trade and hedge volatile swings in Bitcoin prices effectively.The violation of constant volatility and the log-normality assumption of the Black–Scholes option pricing model led to the discovery of the volatility smile,smirk,or skew in options markets.These stylized facts;that is,the volatility smile and implied volatilities implied by the option prices,are well documented in the option literature for almost all financial markets.These are expected to be true for Bitcoin options as well.The data sets for the study are based on short-dated Bitcoin options(14-day maturity)of two time periods traded on Deribit Bitcoin Futures and Options Exchange,a Netherlandsbased cryptocurrency derivative exchange.The estimated results are compared with benchmark Black–Scholes implied volatility values for accuracy and efficiency analysis.This study has two aims:(1)to provide insights into the volatility smile in Bitcoin options and(2)to estimate the implied volatility of Bitcoin options through numerical approximation techniques,specifically the Newton Raphson and Bisection methods.The experimental results show that Bitcoin options belong to the commodity class of assets based on the presence of a volatility forward skew in Bitcoin option data.Moreover,the Newton Raphson and Bisection methods are effective in estimating the implied volatility of Bitcoin options.However,the Newton Raphson forecasting technique converges faster than does the Bisection method.展开更多
The close relationship between the English words and culture is analyzed in this article.Only by understanding the hidden cultural meanings in the English words,can college students truly have a good command of them a...The close relationship between the English words and culture is analyzed in this article.Only by understanding the hidden cultural meanings in the English words,can college students truly have a good command of them and can their communicative ability be improved.展开更多
The yield on the 10-year U.S.Treasury Note is among the most cited interest rates by investors,policymakers,and financial institutions.We show that the 10-year Treasury yield’s forward-looking volatility,a VIX-style ...The yield on the 10-year U.S.Treasury Note is among the most cited interest rates by investors,policymakers,and financial institutions.We show that the 10-year Treasury yield’s forward-looking volatility,a VIX-style measure that is a proxy for uncertainty about future interest rates,is a useful state variable capable of predicting the returns and volatility of crude oil prices over the near term.Using monthly data from 2003 to 2020,we document that higher implied volatility in the 10-year U.S.Treasury derivatives market predicts declining oil prices and higher forward-looking volatility in those prices.Our results are robust to different subsamples and various empirical designs.展开更多
INTRODUCTION Surface waves propagating along the seafloor are general ly called Scholte waves,and were first discovered and studied in the early 1950s(Kugler et al.,2005;Buchen and Ben-Hador,1996).Scholte waves exhibi...INTRODUCTION Surface waves propagating along the seafloor are general ly called Scholte waves,and were first discovered and studied in the early 1950s(Kugler et al.,2005;Buchen and Ben-Hador,1996).Scholte waves exhibit a dispersion phenomenon,which implies that their velocity varies with frequency.Low-frequency Scholte waves can propagate over long distances on the seabed with little attenuation(Bohlen et al.,2004).The particle mo tion of Scholte waves in a solid medium changes from a retro grade to a prograde ellipse(Klein et al.,2005;McMechan and Yedlin,1981).展开更多
The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos, recently giving rise to intense debates. The proce...The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos, recently giving rise to intense debates. The process of thermalization is intricate, involving many time-evolution trajectories in the reduced Hilbert space of the system. By considering two different expansion forms of the density matrices adopted in the biorthogonal and right-state time evolutions, we derive two versions of the Gorini–Kossakowski–Sudarshan–Lindblad(GKSL)master equations describing the non-Hermitian systems coupled to a bosonic heat bath in thermal equilibrium. By solving the equations, we identify a sufficient condition for thermalization under both time evolutions, resulting in Boltzmann biorthogonal and right-eigenstate statistics, respectively. This finding implies that the recently proposed biorthogonal random matrix theory needs an appropriate revision. Moreover, we exemplify the precise dynamics of thermalization and thermodynamic properties with test models.展开更多
1 Copyright Information For Authors Submission of a manuscript implies:that the work described has not been published before(except in the form of an abstract or as part of a published lecture,review,or thesis);that i...1 Copyright Information For Authors Submission of a manuscript implies:that the work described has not been published before(except in the form of an abstract or as part of a published lecture,review,or thesis);that it is not under consideration for publication elsewhere;that its publication has been approved by all co-authors,if any,as well astacitly or explicitly-by the responsible authorities at the institution where the work was carried out.展开更多
Although research on microplastics(MPs)interactions with other soil pollutants is increasingly becoming available,most studies do not consider risks to soil fertility or plant growth.This review aims:1)to summarize th...Although research on microplastics(MPs)interactions with other soil pollutants is increasingly becoming available,most studies do not consider risks to soil fertility or plant growth.This review aims:1)to summarize the results of current studies on interactions between MPs,heavy metals,and organic pollutants;and 2)subsequently evaluate risks to the soil-plant nexus.Available-literature shows that polypropylene,polyethylene and polylactic acid increase cadmium(Cd)bioavailability and subsequently reduce root growth.Such effects are not evident in sandy or clay soils due to the formation of CdCO3 and iron-oxide by altered bacterial communities that stabilize Cd contamination.Chronic instead of short-term exposure to polystyrene in copper(Cu)-polluted soils decreases crop yield.With coexistence of MPs and lead(Pb)in soil,the uptake of Pb in crops increases,causing altered malondialdehyde content and superoxide dismutase and guaiacol peroxidase activities.Moreover,co-toxicity of polystyrene or polytetrafluoroethylene with arsenic(As)decreases root biomass,photosynthesis rate and the chlorophyll-a content.In alkaline soil,polyvinyl-chloride could decrease the bioavailability of MeHg due to changes in the abundance of Proteobacteria,and Firmicutes.We also found strong interactions between MPs and organic pollutants.Polystyrene decreases negative impacts of sulfamethazine on bacterial diversity,and structure in soil.Polyethylene,polyvinyl-chloride and polystyrene have a strong adsorption capacity for 17β-estradiol.This implies that 17β-estradiol toxicity can be reduced by these MPs.At low concentrations,polyethylene,polypropylene,and polystyrene have low affinity to diazepam.In conclusion,serious ecological risks are associated with MPs and other pollutants'interactions to soil-plant system.展开更多
Conversational Implicature Theory is one important theory of pragmatics. It focuses on the implied meaning of the speakers and plays an important role in speech communication.
设l∈N,δ=k/p-k+1/2,以及<p<1.本文的主要结果是建立广义BochnerRiesz平均的核的某种分解: ((1-|ξ|~l)~σ+)^(x)=sum from f=1 to J(k,l,p) b_f((1-|ξ|~2)ь+ζ)^(x)+T(|x|),其中T满足 T^(n+1)(s)≤cmin{(1+s)_(k-n-2),(1+s)^(...设l∈N,δ=k/p-k+1/2,以及<p<1.本文的主要结果是建立广义BochnerRiesz平均的核的某种分解: ((1-|ξ|~l)~σ+)^(x)=sum from f=1 to J(k,l,p) b_f((1-|ξ|~2)ь+ζ)^(x)+T(|x|),其中T满足 T^(n+1)(s)≤cmin{(1+s)_(k-n-2),(1+s)^(-k,p)},0<s<∞以及n=[K(1/p-1)]·作为上述分解的一个直接结果,我们得到:临界阶广义Bochner-Riesz平均在H^p(R^k)上的a.e.收敛性。展开更多
To discover new chemotypes of nematicides with proper toxicological profiles, a series of novel 1,2,3-benzotriazin-4-one derivatives were synthesized and further bioevaluated. The bioassay results showed that most of ...To discover new chemotypes of nematicides with proper toxicological profiles, a series of novel 1,2,3-benzotriazin-4-one derivatives were synthesized and further bioevaluated. The bioassay results showed that most of the synthesized compounds were endowed with moderate to good control efficacy against Meloidogyne incognita at 10.0 mg/L in vivo. Among them, compounds 6k and 6p displayed 100%inhibitory activities at this concentration, which implied that they could be used as lead compounds for promising nematicides.展开更多
Glyphosate has been used worldwide for nearly 40 years,and 30 types of resistant weeds have been reported.Glyphosate is mass-produced and widely used in China,but few studies and reports on glyphosate-resistant weeds ...Glyphosate has been used worldwide for nearly 40 years,and 30 types of resistant weeds have been reported.Glyphosate is mass-produced and widely used in China,but few studies and reports on glyphosate-resistant weeds and resistance mechanisms exist.Previous studies found a goosegrass species with high glyphosate resistance from orchards in South China and its glyphosate resistant mechanism was described in this study.The cDNAof 5-enolpyruvylshikimate-3-phosphate synthase（EPSPS,EC 2.5.1.19）,the target enzyme of glyphosate,was cloned from the glyphosate-resistant and-susceptible goosegrass,respectively,and referred as EPSPS-R and EPSPS-S.The Pro106 residue was known to be involved in the glyphosate resistance in most goosegrass populations.However,sequence analysis did not find the mutation at the Pro106 residue in the R biotype EPSPS amino acid sequence.The residue 133 and 382 was mutated in the R biotype EPSPS amino acid sequence instead,but it did not affect the EPSPS-S and EPSPS-R genes sensitivities to glyphosate.RT-PCR and Western blot analyses suggested that EPSPS mRNA and protein are mainly present in the shoot tissues both in the R and S goosegrass biotypes.The EPSPS-R rapidly responds to the glyphosate in R-biotype goosegrass and the induced expression was detected at 12 h post glyphosate treatment.The mRNA and protein expression of EPSPS-R increased constantly as the increasing concentration of glyphosate.However,the expression of the EPSPS-S was not induced significantly by glyphosate in the S goosegrass biotype.Quantification of real-time PCR results showed that the copy number of the EPSPS in R-biotype goosegrass was 4.7 times higher than that in the S goosegrass biotype.All the results implied that EPSPS gene amplification might mainly caused the glyphosate resistance of a goosegrass population collected from orchards in South China.展开更多
修辞学是英语专业学生在二、三年级必学的一个内容,也是教学的重点,各套教材在这一阶段对此都有安排.英语在其漫长的语言发展史中,逐步形成了丰富的修辞手法,其中最常见也最重要的可算simile明喻.metaphor暗喻.personification拟人、hyp...修辞学是英语专业学生在二、三年级必学的一个内容,也是教学的重点,各套教材在这一阶段对此都有安排.英语在其漫长的语言发展史中,逐步形成了丰富的修辞手法,其中最常见也最重要的可算simile明喻.metaphor暗喻.personification拟人、hyper-bole夸张、euphemism委婉和metonymy借代这几种了.在数年的教学实践中.笔者发现.metaphor和metonymy是其中较易混淆的两种,学生们常感到难以区分,判断中错误率较高.问题出在哪里呢?关键是没有很好掌握两种修辞格的本质和区别.首先让我们来看看它们的定义.由于英汉修辞格的名称和含义不是完全对应的.所以我们着重看对英语修辞格的诠释:Metaphor—A metaphor,like a simile,alsomakes a comparison between two unlike ele-ments,but unlike a simile,this Comparisonis implied,rather than stated.《英汉辞海》的metaphor一条是:用一个词或短语指出常见的一种物体或概念以代替另一种,从而暗示它们之间的相似之处.展开更多
Volatility is an important variable in the financial market. We propose a model-free implied volatility method to measure the volatility and test the volatility risk premium. The model-free implied volatility does not...Volatility is an important variable in the financial market. We propose a model-free implied volatility method to measure the volatility and test the volatility risk premium. The model-free implied volatility does not depend on the option pricing model, and extracts information from all the option contracts. We provide empirical evidence from the S & P 500 index option that model-free implied volatility is more accurate to forecast the future volatility and the volatility risk premium does not exist.展开更多
The Catcher in the Rye has been popular with readers since its publication,and critics at home and abroad have also conducted a lot of research on it.But they mainly proceed from the author and the text to evaluate an...The Catcher in the Rye has been popular with readers since its publication,and critics at home and abroad have also conducted a lot of research on it.But they mainly proceed from the author and the text to evaluate and analyze,ignoring the readers who are essential participants in text interpretation in the eyes of reader-response critics.In order to make up for this shortcoming,this article will take Iser’s reader-response criticism as a research perspective,starting from the three aspects of implied reader,response-inviting structure,and gaps to explore the interaction between the text of The Catcher in the Rye and the readers during the reading process.This research is expected to provide a new interpretation of this novel and provide reference for future research in related fields.展开更多
文摘Modeling implied volatility(IV)is important for option pricing,hedging,and risk management.Previous studies of deterministic implied volatility functions(DIVFs)propose two parameters,moneyness and time to maturity,to estimate implied volatility.Recent DIVF models have included factors such as a moving average ratio and relative bid-ask spread but fail to enhance modeling accuracy.The current study offers a generalized DIVF model by including a momentum indicator for the underlying asset using a relative strength index(RSI)covering multiple time resolutions as a factor,as momentum is often used by investors and speculators in their trading decisions,and in contrast to volatility,RSI can distinguish between bull and bear markets.To the best of our knowledge,prior studies have not included RSI as a predictive factor in modeling IV.Instead of using a simple linear regression as in previous studies,we use a machine learning regression algorithm,namely random forest,to model a nonlinear IV.Previous studies apply DVIF modeling to options on traditional financial assets,such as stock and foreign exchange markets.Here,we study options on the largest cryptocurrency,Bitcoin,which poses greater modeling challenges due to its extreme volatility and the fact that it is not as well studied as traditional financial assets.Recent Bitcoin option chain data were collected from a leading cryptocurrency option exchange over a four-month period for model development and validation.Our dataset includes short-maturity options with expiry in less than six days,as well as a full range of moneyness,both of which are often excluded in existing studies as prices for options with these characteristics are often highly volatile and pose challenges to model building.Our in-sample and out-sample results indicate that including our proposed momentum indicator significantly enhances the model’s accuracy in pricing options.The nonlinear machine learning random forest algorithm also performed better than a simple linear regression.Compared to prevailing option pricing models that employ stochastic variables,our DIVF model does not include stochastic factors but exhibits reasonably good performance.It is also easy to compute due to the availability of real-time RSIs.Our findings indicate our enhanced DIVF model offers significant improvements and may be an excellent alternative to existing option pricing models that are primarily stochastic in nature.
基金The National Natural Science Foundation of China (No.70671025)
文摘Using support vector regression （SVR）, a novel non-parametric method for recovering implied risk-neutral probability density function （IRNPDF） is investigated by solving linear operator equations. First, the SVR principle for function approximation is introduced, and an SVR method for solving linear operator equations with knowing some values of the right-hand function and without knowing its form is depicted. Then, the principle for solving the IRNPDF based on SVR and the method for constructing cross-kernel functions are proposed. Finally, an empirical example is given to verify the validity of the method. The results show that the proposed method can overcome the shortcomings of the traditional parametric methods, which have strict restrictions on the option exercise price; meanwhile, it requires less data than other non-parametric methods, and it is a promising method for the recover of IRNPDF.
文摘This paper deals with options on assets, such as stocks or indexes, which pay cash dividends. Pricing methods which consider discrete dividends are usually computationally expensive and become infeasible when one considers multiple dividends paid during the option lifetime. This is the case of long-term options and options on indexes. The first purpose of this paper is to assess efficient and accurate numerical procedures which yield consistent prices for both European and American options when the underlying asset pays discrete dividends. The authors then analyze some methodologies to extract information on implied volatilities and dividends from quoted option prices. Implied dividends can also be computed using a modified version of the well-known put-call parity relationship. This technique is straightforward, nevertheless, its use is limited to European options, and when dealing with equities, most traded options are of American type. As an alternative, the numerical inversion of pricing methods, such as efficient interpolated binomial method, can be used. This paper applies different procedures to obtain implied volatilities and dividends of listed stocks of the Italian derivatives market （IDEM）.
基金Supported by the National Natural Science Foundation of China(11171349)
文摘This paper concerns an inverse problem of recovering implied volatility in short-term interest rate model from the market prices of zero-coupon bonds. Based on lineariza-tion, an analytic solution, which is given as a power series, is derived for the direct problem.By neglecting high order terms in the power series, an integral equation about the pertur-bation of volatility is formulated and the Tikhonov regularization method is applied to solvethe integral equation. Finally numerical experiments are given and the results show that the method is effective.
文摘The recently developed Bitcoin futures and options contracts in cryptocurrency derivatives exchanges mark the beginning of a new era in Bitcoin price risk hedging.The need for these tools dates back to the market crash of 1987,when investors needed better ways to protect their portfolios through option insurance.These tools provide greater flexibility to trade and hedge volatile swings in Bitcoin prices effectively.The violation of constant volatility and the log-normality assumption of the Black–Scholes option pricing model led to the discovery of the volatility smile,smirk,or skew in options markets.These stylized facts;that is,the volatility smile and implied volatilities implied by the option prices,are well documented in the option literature for almost all financial markets.These are expected to be true for Bitcoin options as well.The data sets for the study are based on short-dated Bitcoin options(14-day maturity)of two time periods traded on Deribit Bitcoin Futures and Options Exchange,a Netherlandsbased cryptocurrency derivative exchange.The estimated results are compared with benchmark Black–Scholes implied volatility values for accuracy and efficiency analysis.This study has two aims:(1)to provide insights into the volatility smile in Bitcoin options and(2)to estimate the implied volatility of Bitcoin options through numerical approximation techniques,specifically the Newton Raphson and Bisection methods.The experimental results show that Bitcoin options belong to the commodity class of assets based on the presence of a volatility forward skew in Bitcoin option data.Moreover,the Newton Raphson and Bisection methods are effective in estimating the implied volatility of Bitcoin options.However,the Newton Raphson forecasting technique converges faster than does the Bisection method.
文摘The close relationship between the English words and culture is analyzed in this article.Only by understanding the hidden cultural meanings in the English words,can college students truly have a good command of them and can their communicative ability be improved.
文摘The yield on the 10-year U.S.Treasury Note is among the most cited interest rates by investors,policymakers,and financial institutions.We show that the 10-year Treasury yield’s forward-looking volatility,a VIX-style measure that is a proxy for uncertainty about future interest rates,is a useful state variable capable of predicting the returns and volatility of crude oil prices over the near term.Using monthly data from 2003 to 2020,we document that higher implied volatility in the 10-year U.S.Treasury derivatives market predicts declining oil prices and higher forward-looking volatility in those prices.Our results are robust to different subsamples and various empirical designs.
基金supported by the research project of the China National Petroleum Corporation(No.2021ZG02)National Natural Science Foundation of China(Nos.42004091,62127815,42150201)+1 种基金Beijing Natural Science Foundation(No.8222030)sponsored by the Chinese“111”project(No.B20011).
文摘INTRODUCTION Surface waves propagating along the seafloor are general ly called Scholte waves,and were first discovered and studied in the early 1950s(Kugler et al.,2005;Buchen and Ben-Hador,1996).Scholte waves exhibit a dispersion phenomenon,which implies that their velocity varies with frequency.Low-frequency Scholte waves can propagate over long distances on the seabed with little attenuation(Bohlen et al.,2004).The particle mo tion of Scholte waves in a solid medium changes from a retro grade to a prograde ellipse(Klein et al.,2005;McMechan and Yedlin,1981).
基金supported by the National Key Research and Development Program of China (Grant No.2022YFA1402700)the National Natural Science Foundation of China (Grant Nos.12174020,12088101,11974244,and U2230402)。
文摘The application of the eigenstate thermalization hypothesis to non-Hermitian quantum systems has become one of the most important topics in dissipative quantum chaos, recently giving rise to intense debates. The process of thermalization is intricate, involving many time-evolution trajectories in the reduced Hilbert space of the system. By considering two different expansion forms of the density matrices adopted in the biorthogonal and right-state time evolutions, we derive two versions of the Gorini–Kossakowski–Sudarshan–Lindblad(GKSL)master equations describing the non-Hermitian systems coupled to a bosonic heat bath in thermal equilibrium. By solving the equations, we identify a sufficient condition for thermalization under both time evolutions, resulting in Boltzmann biorthogonal and right-eigenstate statistics, respectively. This finding implies that the recently proposed biorthogonal random matrix theory needs an appropriate revision. Moreover, we exemplify the precise dynamics of thermalization and thermodynamic properties with test models.
文摘1 Copyright Information For Authors Submission of a manuscript implies:that the work described has not been published before(except in the form of an abstract or as part of a published lecture,review,or thesis);that it is not under consideration for publication elsewhere;that its publication has been approved by all co-authors,if any,as well astacitly or explicitly-by the responsible authorities at the institution where the work was carried out.
基金gratefully acknowledge funding from the Postdoctoral Directional Training Foundation of Yunnan(Grant No.EO3A581261)CAS-President’s International Fellowship Initiative(2021PB00094)+1 种基金National Natural Science Foundation of China(Grant No.31861143002)Prof.Jianchu Xu acknowledges funding from Yunnan Department of Sciences and Technology of China(Grant Nos 202101AS070045,202205 AM070007,202302AE090023,202303AP140001).
文摘Although research on microplastics(MPs)interactions with other soil pollutants is increasingly becoming available,most studies do not consider risks to soil fertility or plant growth.This review aims:1)to summarize the results of current studies on interactions between MPs,heavy metals,and organic pollutants;and 2)subsequently evaluate risks to the soil-plant nexus.Available-literature shows that polypropylene,polyethylene and polylactic acid increase cadmium(Cd)bioavailability and subsequently reduce root growth.Such effects are not evident in sandy or clay soils due to the formation of CdCO3 and iron-oxide by altered bacterial communities that stabilize Cd contamination.Chronic instead of short-term exposure to polystyrene in copper(Cu)-polluted soils decreases crop yield.With coexistence of MPs and lead(Pb)in soil,the uptake of Pb in crops increases,causing altered malondialdehyde content and superoxide dismutase and guaiacol peroxidase activities.Moreover,co-toxicity of polystyrene or polytetrafluoroethylene with arsenic(As)decreases root biomass,photosynthesis rate and the chlorophyll-a content.In alkaline soil,polyvinyl-chloride could decrease the bioavailability of MeHg due to changes in the abundance of Proteobacteria,and Firmicutes.We also found strong interactions between MPs and organic pollutants.Polystyrene decreases negative impacts of sulfamethazine on bacterial diversity,and structure in soil.Polyethylene,polyvinyl-chloride and polystyrene have a strong adsorption capacity for 17β-estradiol.This implies that 17β-estradiol toxicity can be reduced by these MPs.At low concentrations,polyethylene,polypropylene,and polystyrene have low affinity to diazepam.In conclusion,serious ecological risks are associated with MPs and other pollutants'interactions to soil-plant system.
文摘Conversational Implicature Theory is one important theory of pragmatics. It focuses on the implied meaning of the speakers and plays an important role in speech communication.
文摘设l∈N,δ=k/p-k+1/2,以及<p<1.本文的主要结果是建立广义BochnerRiesz平均的核的某种分解: ((1-|ξ|~l)~σ+)^(x)=sum from f=1 to J(k,l,p) b_f((1-|ξ|~2)ь+ζ)^(x)+T(|x|),其中T满足 T^(n+1)(s)≤cmin{(1+s)_(k-n-2),(1+s)^(-k,p)},0<s<∞以及n=[K(1/p-1)]·作为上述分解的一个直接结果,我们得到:临界阶广义Bochner-Riesz平均在H^p(R^k)上的a.e.收敛性。
基金financial supported by the National High Technology Research and Development Program of China(National 863 Program,No.2013AA065202)the National Natural Science Foundation of China(No.21272071)+1 种基金supported by the Special Fund for Agro-scientific Research in the Public Interest(No.201103007)the Fundamental Research Funds for the Central Universities
文摘To discover new chemotypes of nematicides with proper toxicological profiles, a series of novel 1,2,3-benzotriazin-4-one derivatives were synthesized and further bioevaluated. The bioassay results showed that most of the synthesized compounds were endowed with moderate to good control efficacy against Meloidogyne incognita at 10.0 mg/L in vivo. Among them, compounds 6k and 6p displayed 100%inhibitory activities at this concentration, which implied that they could be used as lead compounds for promising nematicides.
基金supported by the National Natural Science Foundation of China(31301683)the Science and Technology Planning Project of Guangdong Province,China(2012A020100009)
文摘Glyphosate has been used worldwide for nearly 40 years,and 30 types of resistant weeds have been reported.Glyphosate is mass-produced and widely used in China,but few studies and reports on glyphosate-resistant weeds and resistance mechanisms exist.Previous studies found a goosegrass species with high glyphosate resistance from orchards in South China and its glyphosate resistant mechanism was described in this study.The cDNAof 5-enolpyruvylshikimate-3-phosphate synthase（EPSPS,EC 2.5.1.19）,the target enzyme of glyphosate,was cloned from the glyphosate-resistant and-susceptible goosegrass,respectively,and referred as EPSPS-R and EPSPS-S.The Pro106 residue was known to be involved in the glyphosate resistance in most goosegrass populations.However,sequence analysis did not find the mutation at the Pro106 residue in the R biotype EPSPS amino acid sequence.The residue 133 and 382 was mutated in the R biotype EPSPS amino acid sequence instead,but it did not affect the EPSPS-S and EPSPS-R genes sensitivities to glyphosate.RT-PCR and Western blot analyses suggested that EPSPS mRNA and protein are mainly present in the shoot tissues both in the R and S goosegrass biotypes.The EPSPS-R rapidly responds to the glyphosate in R-biotype goosegrass and the induced expression was detected at 12 h post glyphosate treatment.The mRNA and protein expression of EPSPS-R increased constantly as the increasing concentration of glyphosate.However,the expression of the EPSPS-S was not induced significantly by glyphosate in the S goosegrass biotype.Quantification of real-time PCR results showed that the copy number of the EPSPS in R-biotype goosegrass was 4.7 times higher than that in the S goosegrass biotype.All the results implied that EPSPS gene amplification might mainly caused the glyphosate resistance of a goosegrass population collected from orchards in South China.
文摘修辞学是英语专业学生在二、三年级必学的一个内容,也是教学的重点,各套教材在这一阶段对此都有安排.英语在其漫长的语言发展史中,逐步形成了丰富的修辞手法,其中最常见也最重要的可算simile明喻.metaphor暗喻.personification拟人、hyper-bole夸张、euphemism委婉和metonymy借代这几种了.在数年的教学实践中.笔者发现.metaphor和metonymy是其中较易混淆的两种,学生们常感到难以区分,判断中错误率较高.问题出在哪里呢?关键是没有很好掌握两种修辞格的本质和区别.首先让我们来看看它们的定义.由于英汉修辞格的名称和含义不是完全对应的.所以我们着重看对英语修辞格的诠释:Metaphor—A metaphor,like a simile,alsomakes a comparison between two unlike ele-ments,but unlike a simile,this Comparisonis implied,rather than stated.《英汉辞海》的metaphor一条是:用一个词或短语指出常见的一种物体或概念以代替另一种,从而暗示它们之间的相似之处.
文摘Volatility is an important variable in the financial market. We propose a model-free implied volatility method to measure the volatility and test the volatility risk premium. The model-free implied volatility does not depend on the option pricing model, and extracts information from all the option contracts. We provide empirical evidence from the S & P 500 index option that model-free implied volatility is more accurate to forecast the future volatility and the volatility risk premium does not exist.
文摘The Catcher in the Rye has been popular with readers since its publication,and critics at home and abroad have also conducted a lot of research on it.But they mainly proceed from the author and the text to evaluate and analyze,ignoring the readers who are essential participants in text interpretation in the eyes of reader-response critics.In order to make up for this shortcoming,this article will take Iser’s reader-response criticism as a research perspective,starting from the three aspects of implied reader,response-inviting structure,and gaps to explore the interaction between the text of The Catcher in the Rye and the readers during the reading process.This research is expected to provide a new interpretation of this novel and provide reference for future research in related fields.
