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Optimal Dividend Strategy in Compound Binomial Model with Bounded Dividend Rates

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Acta Mathematicae Applicatae Sinica 2014年第4期30卷 859-870页

作者： Ji-yang tan Xiang-qun yang School of Mathematics and Computational Science Xiangtan University College of Mathematics and Computer Science Hunan Normal University

We consider the compound binomial model, and assume that dividends are paid to the shareholders according to an admissible strategy with dividend rates bounded by a *** company controls the amount of dividends in order to maximize the cumulative expected discounted dividends prior to ruin. We show that the optimal value function is the unique solution of a discrete HJB equation. Moreover, we obtain some properties of the optimal payment strategy, and offer a simple algorithm for obtaining the optimal strategy. The key of our method is to transform the value function. Numerical examples are presented to illustrate the transformation method.

关键词： compound binomial model optimal dividend strategy transformation

THE UNIQUENESS FOR ALGEBROID FUNCTIONS OF FINITE ORDER

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Acta Mathematica Scientia 2020年第4期40卷 981-990页

作者： yang tan Yinying KONG School of Applied Mathematics Beijing Normal UniversityZhuhai 519085China School of Statistics and Mathematics Institute of Capital Market and Audit Governance Studies for the Great Bay Area(GuangdongHong-KongMacao)Guangdong University of Finance and EconomicsGuangzhou 510320China

In this article,we discuss,by Nevanlinna theory,the influence of multiple values and deficiencies on the uniqueness problem of algebroid *** get several uniqueness theorems of algebroid functions which include an at m... 详细信息

关键词： multiple values deficiencies order uniqueness algebroid functions

Hemorrhoidectomy- making sense of the surgical options

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World Journal of Gastroenterology 2014年第45期20卷 16976-16983页

作者： Danson Yeo Kok-yang tan Department of Surgery Alexandra Health Khoo Teck Puat Hospital

While debate continues as to which is the best surgical method for the treatment of hemorrhoids, none of the currently available surgical methods approach the ideal surgical option, which is one that is effective while being safe and painless. In reality, the less painful the procedure, the more likely it is to be associated with recurrence post-op. Where hemorrhoids surgery is concerned, there isn’t a “one size fits all” option. Most of the randomized controlled trials performed to date include hemorrhoids of various grades and with a focus on only comparing surgical methods while failing to stratify the outcomes according to the grade of hemorrhoid. We believe that surgery needs to be tailored not only to the grade of the hemorrhoids, but also to the size, circumferential nature of the disease, and prevailing symptomatology.

关键词： Hemorrhoidectomy Doppler-guided hemorrhoidal artery ligation Stapler LigaSure Conventional

High-efficiency unidirectional wavefront manipulation for broadband airborne sound with a planar device

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Chinese Physics B 2022年第3期31卷 342-349页

作者： yang tan Bin Liang Jianchun Cheng Key Laboratory of Modern Acoustics(Ministry of Education) Institute of AcousticsDepartment of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210093China

In the past decade, one-way manipulation of sound has attracted rapidly growing attention with application potentials in a plethora of scenarios ranging from ultrasound imaging to noise control. Here we propose a design of a planar device capable of unidirectionally harnessing the transmitted wavefront for broadband airborne sound. Our mechanism is to use the broken spatial symmetry to give rise to different critical angles for plane waves incident along opposite *** the positive direction, the incoming sound is allowed to pass with high efficiency and be arbitrarily molded into the desired shape while any reversed wave undergoes a total reflection. We analytically derive the working bandwidth and incident angle range, and present a practical implementation of our strategy. The performance of our proposed device is demonstrated both theoretically and numerically via distinct examples of production of broadband anomalous refraction,acoustic focusing and non-diffractive beams for forward transmitted wave while virtually blocking the reversed *** advantages of simple design, planar profile, broad bandwidth and high efficiency, our design opens the possibility for novel one-way acoustic device and may have important impact on diverse applications in need of special control of airborne sound.

关键词： acoustic metamaterials one-way wavefront manipulation broadband planar device

Approximation for Ruin Probability in the Sparre Andersen Model with Interest

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Acta Mathematicae Applicatae Sinica 2006年第2期22卷 333-344页

作者： Ji-yang tan Xiang-qun yang Department of Mathematics Hunan Normal University Changsha 410081 China

We consider the Sparre Andersen model modified by the inclusion of interest on the surplus. Approximation for the ultimate ruin probability is derived by rounding. And upper bound and lower bound are also derived by rounding-down and rounding-up respectively. According to the upper bound and lower bound, we can easily obtain the error estimation of the approximation. Applications of the results to the compound Poisson model are given.

关键词： Sparre Andersen model compound Poisson model force of interest ruin probability

Optically pumped Milliwatt Whispering-Gallery microcavity laser

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Light(Science & Applications) 2023年第10期12卷 2154-2162页

作者： Huiqi Li Zhaocong Wang Lei Wang yang tan Feng Chen School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinanChina

Whispering-gallery-mode microcavity lasers possess remarkable characteristics such as high Q factors and compact geometries,making them an essential element in the evolution of ***,solid-state whispering-gallery-mode lasers have previously suffered from low output power and limited optical conversion efficiency,hindering their ***,we present the achievement of milliwatt laser emissions at a wavelength of 1.06µm from a solid-state whispering-gallery-mode *** accomplish this,we construct a whispering-gallery-mode microcavity(with a diameter of 30µm)using a crystalline Nd:YAG thin film obtained through carbon-implantation enhanced etching of a Nd:YAG *** microcavity laser demonstrates a maximum output power of 1.12 mW and an optical conversion efficiency of 12.4%.Moreover,our unique eccentric microcavity design enables efficient coupling of free-space pump light,facilitating integration with a *** integration allowed for single-wavelength laser emission from the waveguide,achieving an output power of 0.5 mW and an optical conversion efficiency of 6.18%.Our work opens up new possibilities for advancing solid-state whispering-gallery-mode lasers,providing a viable option for compact photonic sources.

关键词： laser pumped waveguide

Current research and treatment for gastrointestinal stromal tumors

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World Journal of Gastroenterology 2017年第27期23卷 4856-4866页

作者： Kheng Tian Lim Kok yang tan Department of Surgery Khoo Teck Puat Hospital

Gastrointestinal stromal tumors(GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and have gained considerable research and treatment interest,especially in the last two decades. GISTs are driven by mutations commonly found in the KIT gene and less commonly in the platelet-derived growth factor receptor alpha gene,BRAF gene and succinate dehydrogenase gene. GISTs behave in a spectrum of malignant potential,and both the tumor size and mitotic index are the most commonly used prognostic criteria. Whilst surgical resection can offer the best cure,targeted therapy in the form of tyrosine kinase inhibitors(TKIs) has revolutionized the management options. As the first-line TKI,imatinib offers treatment for advanced and metastatic GISTs,adjuvant therapy in high-risk GISTs and as a neoadjuvant agent to downsize large tumors prior to resection. The emergence of drug resistance has altered some treatment options,including prolonging the first-line TKI from 1 to 3 years,increasing the dose of TKI or switching to second-line TKI. Other newer TKIs,such as sunitinib and regorafenib,may offer some treatment options for imatinib-resistant GISTs. New molecular targeted therapies are being evaluated,such as inhibitors of BRAF,heat shock protein 90,glutamine and mitogenactivated protein kinase signaling,as well as inhibitors of apoptosis proteins antagonist and even immunotherapy. This editorial review summarizes the recent research trials and potential treatment targets that may influence our future patient-specific management of GISTs. The current guidelines in GIST management from Europe,North America and Asia are highlighted.

关键词： Gastrointestinal stromal tumors KIT gene Platelet-derived growth factor receptor alpha gene BRAF gene Succinate dehydrogenase gene CD117 Tyrosine kinase inhibitor Molecular targeted therapy

Fiber and colorectal diseases: Separating fact from fiction

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World Journal of Gastroenterology 2007年第31期13卷 4161-4167页

作者： Kok-yang tan Francis Seow-Choen Department of Surgery Alexandra Hospital Singapore Seow-Choen Colorectal Centre Pte Ltd Singapore

Whilst fruits and vegetables are an essential part of our dietary intake, the role of fiber in the prevention of colorectal diseases remains controversial. The main feature of a high-fiber diet is its poor digestibility. Soluble fiber like pectins, guar and ispaghula produce viscous solutions in the gastrointestinal tract delaying small bowel absorption and transit. Insoluble fiber, on the other hand, pass largely unaltered through the gut. The more fiber is ingested, the more stools will have to be passed. Fermentation in the intestines results in build up of large amounts of gases in the colon. This article reviews the physiology of ingestion of fiber and defecation. It also looks into the impact of dietary fiber on various colorectal diseases. A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has fiber been found to be useful in chronic constipation and irritable bowel syndrome. It is also not useful in the treatment of perianal conditions. The diverticulosis theory should also be challenged. The authors urge clinicians to keep an open mind about fiber. One must be aware of the truths and myths about fiber before recommending it.

关键词： Fiber Physiology Colorectal cancer Constipation Irritable bowel syndrome Diverticulosis Hemorrhoids

Dividend-Reinsurance Strategy in the Sparre Andersen Model

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Acta Mathematica Sinica,English Series 2013年第2期29卷 405-416页

作者： Ji yang tan Lin XIAO Shao Yue LIU Xiang Qun yang Department of Statistics Xiangtan University HPCSIP Key Laboratory Ministry of Education Department of Mathematics Hu'nan Normal University

In this paper, we introduce a reinsurance strategy into the Sparre Andersen risk model with a horizon dividend barrier, which is named dividend-reinsurance strategy. It is shown that the value function of the new strategy far exceeds that of the optimal barrier strategy （even that of the optimal dividend strategy）. Some results on the advantages of the new strategy are obtained, and the methods for computing the value functions are provided. Numerical illustrations for Erlang （2） and compound Poisson risk models are also given.

关键词： Sparre Andersen model reinsurance expected discounted penalty function iteration constant dividend barrier