15 research outputs found

    Boundary Value Problem for r2d2f/dr2+f=f3r^2 {d^2 f/dr^2} + f = f^3 (I): Existence and Uniqueness

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    In this paper we study the equation r2d2f/dr2+f=f3r^2 {d^2 f/dr^2} + f = f^3 with the boundary conditions f(1)=0f(1)=0, f()=1f(\infty)=1 and f(r)>0f(r) > 0 for 1<r<1<r<\infty. The existence of the solution is proved by using topological shooting argument. And the uniqueness is proved by variation method. Using the asymptotics of f(r)f(r) as r1r \to 1, in the following papers we will discuss the global solution for 0<r<0<r<\infty, and give explicit asymptotics of f(r)f(r) as r0r \to 0 and as rr \to \infty, and the connection formulas for the parameters in the asymptotics. Based on these results, we will solve the boundary value problem f(0)=0f(0) =0, f()=1f(\infty) =1, which is the goal of this work. Once people discuss the regular solution of this equation, this boundary value problem must be considered. This problem is useful to study the Yang-Mills potential related equations, and the method used for this equation is applicible to other similar equations.Comment: 12 page

    Boundary Value Problem for r2d2f/dr2+f=f3r^2 d^2 f/dr^2 + f = f^3 (III): Global Solution and Asymptotics

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    Based on the results in the previous papers that the boundary value problem yy+y=y3,y(0)=0,y()=1y'' - y' + y = y^3, y(0) = 0, y(\infty) =1 with the condition y(x)>0y(x) > 0 for 0<x<0<x<\infty has a unique solution y(x)y^*(x), and a=y(0)a^*= y^{*^{'}}(0) satisfies 0<a<1/40<a^*<1/4, in this paper we show that yy+y=y3,<x<0y'' - y' + y = y^3, -\infty < x < 0, with the initial conditions y(0)=0,y(0)=a y(0) = 0, y'(0) = a^* has a unique solution by using functional analysis method. So we get a globally well defined bounded function y(x),<x<+y^*(x), -\infty < x < +\infty. The asymptotics of y(x)y^*(x) as xx \to - \infty and as x+x \to +\infty are obtained, and the connection formulas for the parameters in the asymptotics and the numerical simulations are also given. Then by the properties of y(x)y^*(x), the solution to the boundary value problem r2f+f=f3,f(0)=0,f()=1r^2 f'' + f = f^3, f(0)= 0, f(\infty)=1 is well described by the asymptotics and the connection formulas.Comment: 11 pages, 2 fingure

    Boundary value problem for r

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    We study the equation r2d2f/dr2+f=f3 with the boundary conditions f(1)=0, f(∞)=1, and f(r)>0 for 1<r<∞. The existence of the solution is proved using a topological shooting argument. And the uniqueness is proved by a variation method

    Orthonormal Polynomials on the Unit Circle and Spatially Discrete Painlev\'e II Equation

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    We consider the polynomials ϕn(z)=κn(zn+bn1zn1+>...)\phi_n(z)= \kappa_n (z^n+ b_{n-1} z^{n-1}+ >...) orthonormal with respect to the weight exp(λ(z+1/z))dz/2πiz\exp(\sqrt{\lambda} (z+ 1/z)) dz/2 \pi i z on the unit circle in the complex plane. The leading coefficient κn\kappa_n is found to satisfy a difference-differential (spatially discrete) equation which is further proved to approach a third order differential equation by double scaling. The third order differential equation is equivalent to the Painlev\'e II equation. The leading coefficient and second leading coefficient of ϕn(z)\phi_n(z) can be expressed asymptotically in terms of the Painlev\'e II function.Comment: 16 page

    The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019

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    Background In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15-39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15-39 years to define adolescents and young adults. Findings There were 1.19 million (95% UI 1.11-1.28) incident cancer cases and 396 000 (370 000-425 000) deaths due to cancer among people aged 15-39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59.6 [54.5-65.7] per 100 000 person-years) and high-middle SDI countries (53.2 [48.8-57.9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14.2 [12.9-15.6] per 100 000 person-years) and middle SDI (13.6 [12.6-14.8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23.5 million (21.9-25.2) DALYs to the global burden of disease, of which 2.7% (1.9-3.6) came from YLDs and 97.3% (96.4-98.1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe