This paper is an attempt to study the minimization problem of the risk probability of piecewise deterministic Markov decision processes(PDMDPs)with unbounded transition rates and Borel spaces.Different from the expect...This paper is an attempt to study the minimization problem of the risk probability of piecewise deterministic Markov decision processes(PDMDPs)with unbounded transition rates and Borel spaces.Different from the expected discounted and average criteria in the existing literature,we consider the risk probability that the total rewards produced by a system do not exceed a prescribed goal during a first passage time to some target set,and aim to find a policy that minimizes the risk probability over the class of all history-dependent policies.Under suitable conditions,we derive the optimality equation(OE)for the probability criterion,prove that the value function of the minimization problem is the unique solution to the OE,and establish the existence ofε(≥0)-optimal policies.Finally,we provide two examples to illustrate our results.展开更多
Extensions of Merton’s model(EMM)considering the firm’s payments and generating new types of firm value distribution are suggested.In the open log-value/time space,these distributions evolve from initially normal to...Extensions of Merton’s model(EMM)considering the firm’s payments and generating new types of firm value distribution are suggested.In the open log-value/time space,these distributions evolve from initially normal to negatively skewed ones,and their means are concave-down functions of time.When payments are set to zero or proportional to the firm value,EMM turns into the Geometric Brownian model(GBM).We show that risk-neutral probabilities(RNPs)and the no-arbitraging principle(NAP)follow from GBM.When firm’s payments are considered,RNPs and NAP hold for the entire market for short times only,but for long-term investments,RNPs and NAP just temporarily hold for individual stocks as far as mean year returns of the firms issuing those stocks remain constant,and fail when the mean year returns decline.The developed method is applied to firm valuation to derive continuous-time equations for the firm present value and project NPV.展开更多
BACKGROUND Hereditary non-polyposis colon cancer is a dominantly inherited syndrome of colorectal cancer(CRC),with heightened risk for younger population.Previous studies link its susceptibility to the DNA sequence po...BACKGROUND Hereditary non-polyposis colon cancer is a dominantly inherited syndrome of colorectal cancer(CRC),with heightened risk for younger population.Previous studies link its susceptibility to the DNA sequence polymorphism along with Amsterdam and Bethesda criteria.However,those fail in term of applicability.AIM To determine a clear cut-off of MSH2 gene expression for CRC heredity grouping factor.Further,the study also aims to examine the association of risk factors to the CRC heredity.METHODS The cross-sectional study observed 71 respondents from May 2018 to December 2019 in determining the CRC hereditary status through MSH2 mRNA expression using reverse transcription-polymerase chain reaction and the disease’s risk factors.Data were analyzed through Chi-Square,Fischer exact,t-test,Mann-Whitney,and multiple logistics.RESULTS There are significant differences of MSH2 within CRC group among tissue and blood;yet,negative for significance between groups.Through the blood gene expression fifth percentile,the hereditary CRC cut-off is 11059 fc,dividing the 40 CRC respondents to 32.5%with hereditary CRC.Significant risk factors include age,family history,and staging.Nonetheless,after multivariate control,age is just a confounder.Further,the study develops a probability equation with area under the curve 82.2%.CONCLUSION Numerous factors have significant relations to heredity of CRC patients.However,true important factors are staging and family history,while age and others are confounders.The study also established a definite cut-off point for heredity CRC based on mRNA MSH2 expression,11059 fc.These findings shall act as concrete foundations on further risk factors and/or genetical CRC future studies.展开更多
An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to r...An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to restore the role in energy production. We depict the situation coming from a marvelous history of discoveries started at the beginning of the XX century;heroes are recalled who made possible something that is inconceivable today: design, construction and production of electricity in a few years;that history was tainted by intentional nuclear explosions, </span><i><span style="font-size:12px;font-family:Verdana;">i.e.</span></i><span style="font-size:12px;font-family:Verdana;"> the original sin that we are now paying. Then, we attempt to show that the societal risk is an inherent part of the civilization. Restoring the public trust (towards nuclear fission technology) by matching nuclear safety with the current technological status and advancers in risk assessment is the key objective. The </span></span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">independent assessment</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;">, or a principle for the exploitation of nuclear energy already stated in the 50’s of the previous century, shall then re-appear. This is used to erect the signpost for a </span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">dynamic barricade</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;"> to further reduce the risk of operation of nuclear reactors and to match the design with current technological capabilities and with the frontiers of the research.展开更多
A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard ...A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard alpha anomaly distribution, which reflects the occurrence rate and size of anomalies present in the finished part material of titanium rotors. Since anomalies rarely occur naturally, an experimental method is proposed to obtain the anomaly distribution for titanium alloy aeroengine disks to reflect and equivalently replace the manufacturing development in titanium industry. In general, the anomaly distribution information can be divided into two parts: the Probability of Detection(POD) curve and the detected anomaly distribution, which contains the size and frequency data of the detected anomalies. The distribution can be established based on several appropriate assumptions and derivation steps with different confidence levels of POD curves and detected anomaly distributions. In this case, the distribution can be obtained in a relatively short time as a key input to the probability-based damage tolerance methodology. Then the Probability of Failure(POF) can be calculated, and the value is found to vary with different confidence levels. On this basis, the conservative estimated POF can be obtained in conjunction with confidence levels.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11931018,11961005)Guangdong Province Key Laboratory of Computational Science at the Sun Yat-sen University(No.2020B1212060032)the Natural Science Foundation of Guangxi Province(No.2020GXNSFAA297196)。
文摘This paper is an attempt to study the minimization problem of the risk probability of piecewise deterministic Markov decision processes(PDMDPs)with unbounded transition rates and Borel spaces.Different from the expected discounted and average criteria in the existing literature,we consider the risk probability that the total rewards produced by a system do not exceed a prescribed goal during a first passage time to some target set,and aim to find a policy that minimizes the risk probability over the class of all history-dependent policies.Under suitable conditions,we derive the optimality equation(OE)for the probability criterion,prove that the value function of the minimization problem is the unique solution to the OE,and establish the existence ofε(≥0)-optimal policies.Finally,we provide two examples to illustrate our results.
基金The author is infinitely thankful to his friend and colleague M.Rubinstein for valuable discussions and an invariable interest to his work.The author is also thankful to C.Miller for his high estimation of the author’s efforts.Of course,all errors are author’s full responsibility.
文摘Extensions of Merton’s model(EMM)considering the firm’s payments and generating new types of firm value distribution are suggested.In the open log-value/time space,these distributions evolve from initially normal to negatively skewed ones,and their means are concave-down functions of time.When payments are set to zero or proportional to the firm value,EMM turns into the Geometric Brownian model(GBM).We show that risk-neutral probabilities(RNPs)and the no-arbitraging principle(NAP)follow from GBM.When firm’s payments are considered,RNPs and NAP hold for the entire market for short times only,but for long-term investments,RNPs and NAP just temporarily hold for individual stocks as far as mean year returns of the firms issuing those stocks remain constant,and fail when the mean year returns decline.The developed method is applied to firm valuation to derive continuous-time equations for the firm present value and project NPV.
文摘BACKGROUND Hereditary non-polyposis colon cancer is a dominantly inherited syndrome of colorectal cancer(CRC),with heightened risk for younger population.Previous studies link its susceptibility to the DNA sequence polymorphism along with Amsterdam and Bethesda criteria.However,those fail in term of applicability.AIM To determine a clear cut-off of MSH2 gene expression for CRC heredity grouping factor.Further,the study also aims to examine the association of risk factors to the CRC heredity.METHODS The cross-sectional study observed 71 respondents from May 2018 to December 2019 in determining the CRC hereditary status through MSH2 mRNA expression using reverse transcription-polymerase chain reaction and the disease’s risk factors.Data were analyzed through Chi-Square,Fischer exact,t-test,Mann-Whitney,and multiple logistics.RESULTS There are significant differences of MSH2 within CRC group among tissue and blood;yet,negative for significance between groups.Through the blood gene expression fifth percentile,the hereditary CRC cut-off is 11059 fc,dividing the 40 CRC respondents to 32.5%with hereditary CRC.Significant risk factors include age,family history,and staging.Nonetheless,after multivariate control,age is just a confounder.Further,the study develops a probability equation with area under the curve 82.2%.CONCLUSION Numerous factors have significant relations to heredity of CRC patients.However,true important factors are staging and family history,while age and others are confounders.The study also established a definite cut-off point for heredity CRC based on mRNA MSH2 expression,11059 fc.These findings shall act as concrete foundations on further risk factors and/or genetical CRC future studies.
文摘An attempt is made to locate nuclear technology within a logical context considering history, risks, societal catastrophes and perspectives: the need is identified for a new direction in the exploitation in order to restore the role in energy production. We depict the situation coming from a marvelous history of discoveries started at the beginning of the XX century;heroes are recalled who made possible something that is inconceivable today: design, construction and production of electricity in a few years;that history was tainted by intentional nuclear explosions, </span><i><span style="font-size:12px;font-family:Verdana;">i.e.</span></i><span style="font-size:12px;font-family:Verdana;"> the original sin that we are now paying. Then, we attempt to show that the societal risk is an inherent part of the civilization. Restoring the public trust (towards nuclear fission technology) by matching nuclear safety with the current technological status and advancers in risk assessment is the key objective. The </span></span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">independent assessment</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;">, or a principle for the exploitation of nuclear energy already stated in the 50’s of the previous century, shall then re-appear. This is used to erect the signpost for a </span><span style="font-family:Verdana;font-size:12px;">“</span><span style="font-family:Verdana;font-size:12px;">dynamic barricade</span><span style="font-family:Verdana;font-size:12px;">”</span><span style="font-family:Verdana;font-size:12px;"> to further reduce the risk of operation of nuclear reactors and to match the design with current technological capabilities and with the frontiers of the research.
基金funded by the National Natural Science Foundation of China and Civil Aviation Administration of China(No.U1833109)the Innovation Team of Complex System Safety and Airworthiness of Aero Engine from the Co-Innovation Center for Advanced Aeroengine of China。
文摘A probability-based damage tolerance methodology has been proposed to improve the recognition of material anomalies, especially hard alpha(TiN) anomalies for aeroengine rotor disks. A key input to this method is hard alpha anomaly distribution, which reflects the occurrence rate and size of anomalies present in the finished part material of titanium rotors. Since anomalies rarely occur naturally, an experimental method is proposed to obtain the anomaly distribution for titanium alloy aeroengine disks to reflect and equivalently replace the manufacturing development in titanium industry. In general, the anomaly distribution information can be divided into two parts: the Probability of Detection(POD) curve and the detected anomaly distribution, which contains the size and frequency data of the detected anomalies. The distribution can be established based on several appropriate assumptions and derivation steps with different confidence levels of POD curves and detected anomaly distributions. In this case, the distribution can be obtained in a relatively short time as a key input to the probability-based damage tolerance methodology. Then the Probability of Failure(POF) can be calculated, and the value is found to vary with different confidence levels. On this basis, the conservative estimated POF can be obtained in conjunction with confidence levels.
