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Selected References on quasilinear elliptic PDE
ChinaAbel 2012-4-3 16:26
untill May 10, 2005 Books lecture notes 1. H. Aikava, M Essen, Akawa, Potential theory selected topics, Lecture notes in Math. 1633, Springer-Verlag, 1996 2. E. DiBenedetto, Degenerate parabolic equations. Springer-Verlag, New York, 1993 3. P. Drabek, A. Kufner, F. Nicolosi, Quasilinear elliptic equations with degenerations and singularities, Walter de Gruyter, Berlin. 1997 4. Giaquinta, Mariano Multiple integrals in the calculus of variations and nonlinear elliptic systems. Annals of Mathematics Studies, 105. Princeton University Press, Princeton, NJ, 1983. 5. E. Giusti, Direct methods in the calculus of variations, World Scientific Publishing Co., Inc., River Edge, NJ, 2003. 6. Juha Heinonen, Tero Kilpel¨ainen, Olli Martio, Nonlinear potential theory of degenerate elliptic equations. Oxford Univ. Press, Oxford, 1993. (2nd edition, DOVER PUBN INC,2006 ) 7. Ladyzhenskaya, O. A.; Uraltseva, N. N. Line˘ınye i kvaziline˘ınye uravneniya llipticheskogo tipa. (Russian) Second edition, revised. Izdat. “Nauka”, Moscow, 1973. 576 pp. 8. Ireneo Peral, Multiplicity of solutions for the p-Laplacian. Int. center for theoretical physics, Trieste, 1997 9. The p-Harmonic Equation and Recent Advances in Analysis - Contemporary Mathematics 370, Ed. Pietro Poggi-Corradini, Kansas State University, Editor - AMS, 2005 10. M. Struwe, Variational methods with applications, Sec. Ed. Springer-Verlag, New York, 1993 Papers From 2000 on 1. W. Allegretto, Sturm theorems for degenerate elliptic equations. Proc. Amer. Math. Soc. 129:10 (2001),3031–3035. 2. A. Anane, N Tsouli, On a resonance condition between the first and the second eigenvalues for the p-Laplacian, Int. J. Math. Sci., 26:10 (2001) 625 - 634. 3. Aronsson, Gunnar; Crandall, Michael G.; Juutinen, Petri A tour of the theory of absolutely minimizing functions. Bull. Amer. Math. Soc. (N.S.) 41 (2004), no. 4, 439–505. 4. C. Azizieh, P. Clement, E. Mitidieri, Existence and a priori estimates for positive solutions of p-Laplace systems. J. Diff. Equa. 184:2 (2002) 422–442. 5. V. Benci, A. M. Micheletti and D. Visetti, An Eigenvalue Problem for a Quasilinear Elliptic Field Equation, J. Diff. Equa. 184:2(2002) 299-320 6. G. Bognar, P. Drabek, The p-Laplacian equation with superlinear and supercritical growth, multiplicity of radial solutions. Nonlinear Anal. 60:4 (2005)719–728. 7. T. Bhattacharya, On the properties of 1-harmonic functions and an application to capacitary convex rings. Electron. J. Diff. Equa. 101 (2002) 8. H. Brezis, Y. Li, Topology and Sobolev spaces. J. Funct. Anal. 183:2 (2001) 321–369. 9. P. Clement, J. Fleckinger, E. Mitidieri, F. de Thelin, Existence of positive solutions for a nonvariational quasilinear elliptic system. J. Diff. Equa. 166:2 (2000) 455–477. 10. M. Cuesta, D. G: de Figueiredo, J. P. Gossez, A nodal domain property for the p−Laplacian. C. R. Acad. Sci. I - Math. 330:8 (2000) 669-673. 11. L. Damascelli, F. Pacella, Monotonicity and symmetry results for p-Laplace equations And applications, Adv. Diff. Equa. 5 (2000) 1179 1200. , 1 p 2, Via the moving plane method. 12. P. Drabek, P. Girg, P. Tak*ˇc, M. Ulm, The Fredholm alternative for the p-Laplacian: bifurcation from infinity, existence and multiplicity. Indiana Univ. Math. J. 53:2 (2004) 433–482. 13. Y. Du, and Z. Guo, Liouville type results and eventual flatness of positive solutions for p−Laplace equations. Adv. Diff. Equa. 7 (2002) 1479 - 1512. 14. M. Garcia-Huidobro, R. Manasevich, J. Serrin, M. Tang, C. Yarur, Ground states and free boundary problems for the n-Laplacian in n-dimensional space . J. Func. Anal. , 172 (2000) 177-201. 15. M. Garcia-Huidobro, R. Manasevich, P. Yan, M. Zhang, A p-Laplacian problem with a multipoint boundary condition. Nonlinear Anal. 59:4 (2004) 319–333. 16. Z. Guo, J. R. L. Webb, Structure of boundary blow-up solutions for quasi-linear elliptic problems. II. Small and intermediate solutions. J. Diff. Equa. 211:1 (2005) 187–217. 17. Z. Guo and J. R. L. Webb, Spike-Layer solutions for quasilinear elliptic equations. Comm. Contemp. Math. 5:6 (2003) 883–920. 18. I. E. Hadi, N. Tsouli, Strong unique continuation of the eigenfunctions for the p-Laplacian operator, Int. J. Math. Math. Sci. 25:3 (2001) 213-216. 19. F. Hang, F. Lin, Topology of Sobolev mappings. Math Res. Lett. 8:3 (2001) 321–330 20. F. Hang, F. Lin, Topology of Sobolev mappings. II. Acta Math. 191:1 (2003) 55–107. 21. F. Hang, F. Lin, Topology of Sobolev mappings. III. Comm. Pure Appl. Math. 56:10 (2003) 1383–1415. 22. Juutinen, Petri; Lindqvist, Peter, A theorem of Rado’s type for the solutions of a quasi-linear equation. Math. Res. Lett. 11 (2004), no. 1, 31–34. 23. Juutinen, Petri; Lindqvist, Peter; Manfredi, Juan J., On the equivalence of viscosity solutions and weak solutions for a quasi-linear equation. SIAM J. Math. Anal. 33 (2001), no. 3, 699– 717 24. Juutinen, Petri; Lindqvist, Peter; Manfredi, Juan J., The infinity Laplacian: examples and observations. Papers on analysis, 207–217, Rep. Univ. Jyv¨askyl¨a Dep. Math. Stat., 83, Univ. Jyv¨askyl¨a, Jyv¨askyl¨a, 2001. 25. Lindqvist, Peter; Manfredi, Juan; Saksman, Eero, Superharmonicity of nonlinear ground states. Rev. Mat. Iberoamericana 16 (2000), no. 1, 17–28. 26. R. Manasevich, J. Mawhin, The spectrum of p-Laplacian systems under Dirichlet, Neumann and periodic boundary conditions. Morse theory, minimax theory and their applications to nonlinear differential equations, 201–216, New Stud. Adv. Math., 1, Int. Press, Somerville, MA, 2003. 27. R. Manasevich, G. Sweers, A comparison result for perturbed radial p-Laplacians. J. Math. Anal. Appl. 291:1 (2004) 1–19. 28. P. Pucci, J. Serrin, The strong maximum principle revisited. J. Diff. Equa. 196:1 (2004), 1–66. 29. J. Serrin, H. Zou, Cauchy-Liouville and universal boundedness theorems for quasilinear elliptic equations and inequalities. Acta Math. 189:1 (2002) 79–142. 30. P. Takaˇc, On the Fredholm alternative for the p-Laplacian at the first eigenvalue. Indiana Univ. Math. J. 51:1 (2002) 187–237. 1990–1999 1. Acerbi, E.; Fusco, N. Local regularity for minimizers of nonconvex integrals., Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4) 16 (1989), no. 4, 603–636 (1990) 2. W. Allegretto, Y. X. Huang, Principal eigenvalues and Sturm comparison via Picone’s identity. J. Diff. Equa. 156:2 (1999) 427–438. 3. Alvarez, O. Lasry, J.-M.; Lions, P.-L., Convex viscosity solutions and state constraints. J. Math. Pures Appl. (9) 76 (1997), no. 3, 265–288. 4. A. Ambrosetti, J. Garcia Azorero, I. Pearal Alonso, Multiplicity results for some nonlinear elliptic equations, J. Func. Anal. 137 ( 1996) 219-242. 5. A. Anane, N Tsouli, On the second eigenvalue of the p-Laplacian, Pitman Research Notes in Math. 343 (1996) 1-9. 6. G. Aronsson, On p−harmonic functions, convex duality and an asymptotic formula for injection mould filling. Euro. J of Appl. Math. 7 ( 1996 ) 417 - 437 7. P. A. Binding, Y. X. Huang, Existence and nonexistence of positive eigenfunctions for the p−laplacian, Proc. Amer. Math. Soci. 123:6 (1995) 1383- 1388 8. Y. Cheng, An eigenvalue problem for quasilinear elliptic equations, Math. Nachr. 196 (1998) pp.43-59 9. Y. Cheng, On the positive solutions of a quasilinear elliptic system, Czech. Math. J. 47:4 (1997) pp.681-687 10. Y. Cheng, H¨older continuity of the inverse of p-Laplacian, J. Math. Anal. Appl. 221:2 (1998) pp.734-748 11. Crandall, Michael G.; Ishii, Hitoshi, The maximum principle for semicontinuous functions. Differential Integral Equations 3 (1990), no. 6, 1001–1014. 12. L. Damascelli, F. Pacella, Monotonicity and symmetry results for p-Laplace equations , 1 p 2, via the moving plane method. Ann. Scuola Norm. Sup. Pisa CL. Sci. IV Ser. 26 (1998) 689 707. 13. DiBenedetto, E.; Manfredi, J. On the higher integrability of the gradient of weak solutions of certain degenerate elliptic systems.Amer. J. Math. 115 (1993), no. 5, 1107–1134. 14. J. Fleckinger, E. M. Harrel II, F. de Thelin, Boundary behavior and estimates for solutions of equations containing the p−Laplacian. Elctronic J of Diff. Equa. 38 ( 1999) 1 - 19. 15. Fukagai, Nobuyoshi; Ito, Masayuki; Narukawa, Kimiaki, Limit as p ! 1 of p-Laplace eigenvalue problems and L1-inequality of the Poincar type. Differential Integral Equations 12 (1999), no. 2, 183–206. 16. J. Garcia Azorero, I. Peral Alonso, Some results about the existence of a second positive solution in a quasiliear critical problem, Indiana Univ math. J. 43:3 (1994) 941-957 17. J. Garcia Azorero, I. Peral Alonso, Multiplicty of solutions for elliptic problem with critical exponent or with a nonsymmetric term. Trans. Amer. Math. Soci. 323:2 (1991) 877-895. 18. Greco, L., Iwaniec,T. and Sbordone, C., Inverting the p-harmonic operator. Manuscripta Math. 92 (1997), no. 2, 249–258 19. Iwaniec, Tadeusz, p-harmonic tensors and quasiregular mappings. Ann. of Math. (2) 136 (1992), no. 3, 589–624. 20. P. Lindqvist, On the equation r(|ru|p−2ru) + |u|p−2u = 0. Proc. Amer. Math. Soci. 109 (1990) 157 -164. 21. Jensen, Robert, Uniqueness of Lipschitz extensions: minimizing the sup norm of the gradient. Arch. Rational Mech. Anal. 123 (1993), no. 1, 51–74. 22. Juutinen, Petri; Lindqvist, Peter; Manfredi, Juan J. The 1-eigenvalue problem. Arch. Ration. Mech. Anal. 148 (1999), no. 2, 89–105 23. Kilpelinen, Tero, A Rad type theorem for p-harmonic functions in the plane. Electron. J. Differential Equations 1994, No. 09, approx. 4 pp. (electronic). 24. Manfredi, Juan J. Isolated singularities of p-harmonic functions in the plane. SIAM J. Math. Anal. 22 (1991), no. 2, 424–439. 25. J. Serrin, H. Zou, Symmetry of ground states of quasilinear elliptic equations. Arch. Ration. Mech. Anal. 148:4 (1999) 265–290. Until 1989 1. Acerbi, E.; Fusco, N., Regularity for minimizers of nonquadratic functionals: the case 1 p 2. J. Math. Anal. Appl. 140 (1989), no. 1, 115–135. 2. Aronsson, Gunnar Extension of functions satisfying Lipschitz conditions. Ark. Mat. 6 1967 551–561 (1967). 3. Aronsson, Gunnar Representation of a p-harmonic function near a critical point in the plane. Manuscripta Math. 66 (1989), no. 1, 73–95. 4. T. Bhattacharya, Radial symmetry of the first eigenfunction for the p-Laplacian in the ball. Proc. Amer. Math. Soc. 104:1 (1988) 169–174. 5. M. Del Pino, M. Elgueta, R. Manasevich, A homotopic deformation along p of a Leray- Schauder degree result and existence for (|u0|p−2u0)0 + f(t, u) = 0, u(0) = u(T) = 0, p 1. J. Diff. Equa. 80 (1989) 1-13. 6. E. Di Benedetto, C1, local regularity of weak solutions of degenerate elliptic equations. Nonlinear analysis, 7:8 (1983) 827 -850. 7. H. Egnell , Existence and nonexistence for the m−laplace equations involving critical Sobolev exponents. Arch. Rational Mech. Anal. 104 (1988) 57 - 77. 8. J. Garcia Azorero, I. Pearal Alonso, Existence and nonexistence for the p−laplacian: Nonlinear eigenvalues.Comm. Partial Diff. Equa. 12 (1987) 1389 - 1430 9. Iwaniec, T., Projections onto gradient fields and Lp-estimates for degenerated elliptic operators. Studia Math. 75 (1983), no. 3, 293–312. 10. Iwaniec, Tadeusz; Manfredi, Juan J., Regularity of p-harmonic functions on the plane. Rev. Mat. Iberoamericana 5 (1989), no. 1-2, 1–19. 11. Jensen, Robert, Uniqueness criteria for viscosity solutions of fully nonlinear elliptic partial differential equations. Indiana Univ. Math. J. 38 (1989), no. 3, 629–667. 12. Kr`al, J. Some extension results concerning harmonic functions. J. London Math. Soc. (2) 28 (1983), no. 1, 62–70. 13. J. L. Lewis, Regularity of the derivatives of solutions to certain degenerate elliptic equations, Indiana Univ. Math. J 32 (1983) 849-858. 14. G. Lieberman, Boundary regularity for solutions of degenerate elliptic equations. Nonlinear analysis, 12:11 (1988) 1203 -1219. 15. Lindqvist, Peter, On the definition and properties of p-superharmonic functions. J. Reine Angew. Math. 365 (1986), 67–79. 16. Manfredi, Juan J. p-harmonic functions in the plane. Proc. Amer. Math. Soc. 103 (1988), no. 2, 473–479. 17. S. Sakaguchi, Concavity properties of solutions to some degenerate quasilinear elliptic Dirichlet problems. Ann. Scuola Norm. Sup. Pisa 14:3 (1987) 403–421. 18. Manfredi, Juan J.; Weitsman, Allen On the Fatou theorem for p-harmonic functions. Comm. Partial Differential Equations 13 (1988), no. 6, 651–668. 19. P. Tolksdorf, Regularity for a more general class of quasilinear elliptic equations. J. Diff. Equa., 51 (1984) 126 - 150. 20. Uhlenbeck, K., Regularity for a class of non-linear elliptic systems. Acta Math. 138 (1977), no. 3-4, 219–240. (by Yuanji Cheng, Juan J. Manfredi)
个人分类: 非线性科学论文集|0 个评论
水波
热度 1 math611 2011-4-13 10:28
渺渺水波低赤岸,蒙蒙云气淡扶桑。---- 王安石 偏微分方程要介绍的一部分内容是波的传播。内容上需要推导方程和解的讨论,包括弦的振动、膜的振动以及高维体的振动。 理解波的传播可以通过实际观察。这里依据方程做了一视频供参考,帮助理解波传播的性质。详细请见: http://v.youku.com/v_show/id_XMjU4NDMwNzg0.html (高清) 有点搞笑的是居然被Youku放到了“ 原创频道 原创列表 自拍作品 ”,自拍作品哦?是不是骗过了编辑不得而知。 模拟演示的是一滴水滴入水中后荡起的涟漪,可以看见通过堤坝间的小缺口后还会产生衍射。视频还反映了波在边界和堤坝上产生的多次反射。 查阅更多相关主题的贴子: 水波 PDE 波动方程 模拟
3399 次阅读|1 个评论
Functional Analysis,Sobolev Spaces and PDE
ChinaAbel 2010-12-7 13:30
仅限学术研究使用,严禁商业用途,作者和出版社如有异议,我立即删除附件。如果觉得本书比较好,请购买正版图书。也欢迎各位博友讨论本书内容。欢迎学术交流。 Functional Analysis,Sobolev Spaces and Partial Differential Equations (Haim Brezis)(2011) Preface This book has its roots in a course I taught for many years at the University of Paris. It is intended for students who have a good background in real analysis (as expounded, for instance, in the textbooks of G. B. Folland , A. W. Knapp , and H. L. Royden ). I conceived a program mixing elements from two distinct worlds: functional analysis (FA) and partial differential equations (PDEs). The first part deals with abstract results in FA and operator theory. The second part concerns the study of spaces of functions (of one or more real variables) having specific differentiability properties: the celebrated Sobolev spaces, which lie at the heart of the modern theory of PDEs. I show how the abstract results from FA can be applied to solve PDEs. The Sobolev spaces occur in a wide range of questions, in both pure and applied mathematics. They appear in linear and nonlinear PDEs that arise, for example, in differential geometry, harmonic analysis, engineering, mechanics, and physics. They belong to the toolbox of any graduate student in analysis. Unfortunately, FA and PDEs are often taught in separate courses, even though they are intimately connected. Many questions tackled in FA originated in PDEs (for a historical perspective, see, e.g., J. Dieudonn and H. BrezisF. Browder ). There is an abundance of books (even voluminous treatises) devoted to FA. There are also numerous textbooks dealing with PDEs. However, a synthetic presentation intended for graduate students is rare. and I have tried to fill this gap. Students who are often fascinated by the most abstract constructions in mathematics are usually attracted by the elegance of FA. On the other hand, they are repelled by the neverending PDE formulas with their countless subscripts. I have attempted to present a smooth transition from FA to PDEs by analyzing first the simple case of onedimensional PDEs (i.e., ODEsordinary differential equations), which looks much more manageable to the beginner. In this approach, I expound techniques that are possibly too sophisticated for ODEs, but which later become the cornerstones of the PDE theory. This layout makes it much easier for students to tackle elaborate higher-dimensional PDEs afterward. Functional Analysis,Sobolev Spaces and Partial Differential Equations (Haim Brezis)
个人分类: 电子图书(仅限学术研究使用,禁止商业用途)|8395 次阅读|1 个评论
MATLAB求解PDE问题(4)——总结
热度 4 lyknq 2010-10-13 11:16
通过前面三篇的介绍,大家已经能够掌握 PDEToolbox 求解椭圆型方程的用法了。本篇在前面三篇的基础上,大致介绍 PDEToolbox 中一些其它函数的用法,供大家理解。 我们先总结下利用 PDEToolbox 求解 PDE(s) 的基本步骤:第一要把方程化为标准形式,不论是椭圆方程,还是其他类型的方程,均要化为标准形式后才能利用工具箱求解;第二要写出表示求解区域和几何区域文件以及表示边界条件的边界条件文件;完成这两步后,后面的步骤就容易了。依次为网格初始化,加密网格(或者使用自适应网格);根据方程的类型使用相应的计算函数;对结果进行分析计算以及可视化处理。 PDEToolbox 能够求解的方程类型前面也已说过,有椭圆型方程,抛物型方程,双曲型方程,特征值方程,非线性方程五类。其中抛物型和双曲型涉及到时间,应按照要求给出初始值。特征值问题是一个齐次问题,即边界条件中 g=0 , r=0 。非齐次部分将会被自动删去,这在理解工具箱自带的 squareb2 边界条件时尤为重要。 下面以一段程序来尽量多介绍几个函数的用法,关于这些函数的用法大家可以从网络、工具箱的用户说明手册、各种介绍工具箱的数据中得到详细的说明。 g='yourgeom'; b='yourbound'; 以上两行确定几何区域和边界条件 =initmesh('yourgeom'); % 网格初始化 = refinemesh('yourgeom',p,e,t); % 网格加密 = refinemesh('yourgeom',p,e,t); 以上三行初始化网格并加密 c='your content c'; % 系数 a='your content a'; f='your content f'; 以上三行确定方程参数,注意特征值问题是齐次问题,不需要 f U= assempde(b,p,e,t,c,a,f); % 求解椭圆型PDE问题 U=parabolic(u0,tlist,b,p,e,t,c,a,f,d); % 求解抛物型PDE问题 U=hyperbolic(u0,ut0,tlist,b,p,e,t,c,a,f,d); % 求解双曲型PDE问题 =pdeeig(b,p,e,t,c,a,d,r); % 求解特征值PDE问题 U=pdenonlin(b,p,e,t,c,a,f); % 求解非线性PDE问题 U=poisolv(b,p,e,t,f); % 求矩形网格上泊松方程的快速解 以上六行根据自己遇到的问题选定一行即可。如果涉及到时间,需要给出初值等,详细用法可以从 UserGuider 中获取。 pdecont(p,t,U) %绘制等值线图 pdeplot(p,e,t,'PropertyName',PropertyValue,) %一般PDE工具箱绘制函数 pdesurf(p,t,u) % 绘制表面图 以上三行是结果可视化的命令,可以根据自己的需要选择。 上面的示例程序是利用 PDE 工具箱求解 PDE 问题的总体步骤。对于任意一种 PDE ,均可以按照给出的程序步骤进行计算。如果需要对计算结果进行处理,比如说求梯度等, PDE 工具箱也提供了相应的命令,这里就不再介绍了。下面介绍下自适应网格求解 PDE 问题,还命令的用法如下 =adaptmesh(g,b,c,a,f , 'PropertyName',PropertyValue); % 生成自适应网格并求解 PDE 问题 注意,该命令将网格生成和求解问题合在一起了,如果求解非线性 PDE 问题时,属性中的非线性开关应设置为 'on' 。 介绍 PDEToolbox 的这几篇博文到这里就结束了,这也算是对自己这段时间来使用工具箱经验的总结。刚接触时在设定几何区域和边界条件处遇到了很多问题,在挣扎了许久后终于学会如何使用 PDEToolbox 。希望通过这几篇博文,新接触到 PDE 工具箱的人可以更加容易得掌握其用法。大家可以任意使用博文的全部或片段,转载请说明出处,谢谢。
个人分类: 生活点滴|4060 次阅读|12 个评论
MATLAB求解PDE问题(3)——确定边界条件
热度 2 lyknq 2010-10-12 23:46
前一篇给出了如何确定几何区域,本篇接着给出如何确定边界条件,在几何区域和边界条件都确定好之后,就可以利用 PDEToolbox 对给定的 PDE 进行计算了。先回忆下前面的边界条件: 上面的四个边界条件中,前两个是 Dirichlet 边界,后两个是 Neumann 边界。我们先了解下 PDEToolbox 中规定有三种边界条件,一是 Dirichlet 边界条件,一是广义 Neumann 条件,一是混合边界条件(只用于方程组)。这和传统的定义有所不同,按照传统的观点, PDEToolbox 中的广义 Neumann 条件应该是混合边界条件( Robin 边界条件),而传统的 Neumann 边界条件是指边界处的法向导数为零。我们先不考虑方程组, Dirichlet 边界条件和广义 Neumann 条件写成如下形式: 其中 是外法线方向, 是边界法向量与x 轴的夹角。 规定边界条件的 m 文件是 pdebound 函数,该函数并不提供边界条件,而是要求用户按照规定的方法给出边界条件,用户可以自己给定函数的名字。我们计算中给出的边界条件函数是 mybound 。调用格式为 =mybound(p,e,u,time) 。 pdebound 函数中最主要的内容是 bl 矩阵, bl 包括了所有的边界信息。 bl 的每一列都是边界条件矩阵的对应列,每一列都必须满足下面的规则: 第一行是方程的维数 N ,一个方程 N=1 ,两个方程构成的方程组, N=2 ,; 第二行是 Dirichlet 边界条件数 M , Dirichlet 边界条件时 M=N ,广义 Neumann 边界条件时 M=0 ,如果是方程组, 0MN 之间表示混合边界条件; 第三行到第 3+N 2 -1 行是表示 q 的字符串的长度,这个长度按与 q 有关的列方向的次序储存; 第 3+N 2 行到第 3+N 2 +N-1 是表示 g 的字符串的长度; 第 3+N 2 +N 行到第 3+N 2 +N+MN-1 是表示 h 的字符串的长度,这个长度按与 h 有关的列方向的次序储存; 第 3+N 2 +N+MN 行到第 3+N 2 +N+MN+M-1 是表示 r 的字符串的长度; 接下来的行是包括 MATLAB 文本表达式所表示的真实边界条件函数。文本表达式是将实际的表达式通过 double 函数转化为 ASCII 码后的表达式。文本字符串的长度与前面四行规定的长度是一致的,两个字符串之间没有分隔符。可以插入含有下列变量的文本表达式: 二维坐标 x 和 y ; 边界线段参数 s ,弧长的比例。在边界线段的起始处 s=0 ,向着线段的终点处增加到 s=1 ; 外法向量分量 nx , ny 。如果要用到切向量,可以用 tx 和 ty 表示,其中 tx=-ny , ty=nx ; 解 u (除非已指定输入参数 u ); 时间 t (除非已指定输入参数 time )。 注意,在只有一个方程的时候,即 N=1 ,如果 M=0 时,即是广义 Neumann 边界条件,此时不需要表示 表示 Dirichlet 边界条件的 h , r 两行,因此表示 q 和 g 的字符串从第 5 行开始(前四行分别为 N,M,q,g 的指示行);如果 M=1 ,此时表示 h , r 的字符串从第 9 行开始(前六行分别是 N,M,q,g,h,r 的指示行,第七八行表示 q , g ,它们均为 0 , ASCII 码为 48 ) 下面看下我们计算你的例子中边界 mybound 函数的内容: function =mybound(p,e,u,time) % upper=double('2-2*x-x.^2');% y=1上边界条件函数 % down =double('x.^2'); % y=0下边界条件函数 % left =double('y.^2'); % x=0左边界条件函数 % right=double('2-2*y-y.^2'); % x=1右边界条件函数 % upper=upper'; % 转化为列向量 % down =down'; % left =left'; % right=right'; % bl= ; if any(size(u)) =pdeexpd(p,e,u,time,bl); else =pdeexpd(p,e,time,bl); end 规定边界条件的矩阵 bl 较为复杂,详细的解释可以使大家省不少时间,但是也容易把大家整晕,我也是在这方面花费了不少功夫。下面具体分析下 bl 中的两列。第一列对应着上边界条件( Neumann 边界条件): 与边界条件的标准形式比较,有, q=0 , g=2-2*x-x.^2 ,于是第一列可以写为 ' 其中 1 表示 N=1 ,即一个方程, 0 表示 Neumann 边界条件; 1 表示 q 的长度; 10 表示 g 的长度, '0' 表示 q=0 ,长度为 1 ; '2-2*x-x.^3' 表示 g=2-2*x-x.^2 ,转化为 ASCII 码后长度为 10 。因此第一列最终写为 ' 第三列对应着下边界条件,是 Dirichlet 边界条件: 与标准形式比较,有, h=1 , r=x.^2 ,于是第三列可以写为 ' 按顺序依次为, 1 表示 N=1 ,一个方程; 1 表示 Dirichlet 边界条件; 1 表示 q 的长度,此时必为 1 ; 1 表示 g 的长度,此时也必为 1 ; 1 表示 h 的长度是 1 ; 4 表示 r 的长度为 4 ; '0' 表示 q 的值为 0 ( 0 的字符串长度是 1 ); '0' 表示 g 的值是 0 ; '1' 表示 h=1 ( 1 的 ASCII 码是 49 ); 'x.^2' 表示 r=x.^2 ,转化为 ASCII 码后长度是 4 。于是第三列可以写为 ' 此时第三列的长度小于第一列的长度,缺几个长度就可以添加几个 ASCII 码的 0 ,表示空,这样第三列就是 mybound 中的第三列了,如下 ' 最后附上 mybound 的 m 文件,有需要的可以下载。 mybound文件
个人分类: 生活点滴|3904 次阅读|2 个评论
MATLAB求解PDE问题(2)——确定几何区域
lyknq 2010-10-12 18:58
前一篇介绍了如何利用 Matlab 求解椭圆型方程,下面介绍如何确定求解的几何区域。 PDEToolbox 中规定几何区域的 m 文件是 pdegeom.m 。但是 pdegeom 并不是一个可以调用的函数,它只是规定了应该何如定义区域,具体的区域则要根据研究的问题来决定。 函数 pdegeom 释义如下: 参数为 0 个时,即没有参数时,返回边界的段数; 参数为 1 个时,即只有 bs ,返回输出区域边界的参变量范围矩阵 d ; 参数为 2 个时,返回每段边界长度为 s 时的坐标。 函数参数意义 bs 表示指定的边缘线段,如矩形边界为四段,三角开边界肯定为三段。 s 为第 bs 段线段弧长的近似(估计)值, bs 与 s 可以为向量,但是要一一对应,即 bs 为几个值, s 也得为几个值。输出变量 是每条线段起点和终点所对应的坐标。这个函数编制的关键是,函数内边界上的坐标 ((x(t),y(t)) 是用参变量 t 表示的,返回值是求得边界任意长度时的坐标( x(t),y(t) )值,参量可以有很多种选法。 回到前一篇中,给定的方程的求解区域是 的一个正方形,我们将它命名为 mygeom 。下面我们来看下 mygeom 是怎么编写的。 function =mygeom(bs,s) nbs=4; % 表示边界的段数 if nargin==0, x=nbs; % 不给定输入变量时,输出表示几何区域边界的线段数 return end d= ; bs1=bs(:)'; if find(bs11 | bs1nbs), error('PDE:squareg:InvalidBs', 'Non existent boundary segment number.') end if nargin==1, x=d(:,bs1); % 给定一个输入变量时,输出区域边界数据的矩阵 return end x=zeros(size(s)); y=zeros(size(s)); =size(bs); if m==1 n==1, bs=bs*ones(size(s)); % expand bs elseif m~=size(s,1) || n~=size(s,2), error('PDE:squareg:SizeBs', 'bs must be scalar or of same size as s.'); end if ~isempty(s), % 第一段边界 ii=find(bs==1); if length(ii) x(ii)=interp1( , ,s(ii));% 通过参量来确定边界上的值 y(ii)=interp1( , ,s(ii));% end % 第二段边界 ii=find(bs==2); if length(ii) x(ii)=interp1( , ,s(ii)); y(ii)=interp1( , ,s(ii)); end % 第三段边界 ii=find(bs==3); if length(ii) x(ii)=interp1( , ,s(ii)); y(ii)=interp1( , ,s(ii)); end % 第四段边界 ii=find(bs==4); if length(ii) x(ii)=interp1( , ,s(ii)); y(ii)=interp1( , ,s(ii)); end end 编辑完该函数后,可以利用 pdeplot 函数来测试设置的几何区域是否满足要求。在 matlab 命令窗口输入: pdegplot('mygeom'), axis equal =initmesh('mygeom'); pdemesh(p,e,t),axisequal 结果如下: mygeom 的 m 文件放在附件里,大家可以下载。本篇写作时参考了刘平的博客,已在前面指出,另参考了《偏微分方程的MATLAB解法》及《MATLAB PDE Toolbox User Guide》,有兴趣的读者可以参阅。 mygeom文件下载
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MATLAB求解PDE问题(1)——概述、例子
热度 3 lyknq 2010-10-12 14:57
MATLABPDET oolbox 提供利用有限元方法 求解 偏微分方程的 GUI 以及相应的命令行函数。利用该工具箱可以求解椭圆型方程、抛物型方程、双曲型方程、特征值方程以及非线性方程。 PDEToolbox 的功能非常强大,网上有许多利用 PDEToolbox 解决各种物理问题的论文,还有专门介绍工具箱的参考书。 网上的例子虽然很多,但是大部分是介绍 PDE 工具箱自带的一些例子,这些例子中解的区域,边界条件是 PDE 工具箱已经编写好的,直接调用就可以。对于该如何自己设定求解区域及边界条件,却很少有人涉及。网上搜索发现只有 刘平 在博客中详细介绍过求解区域的设定。下面以一个椭圆型方程的例子来详细说明求解的各个步骤,希望对大家能有所帮助。 设要求如下形式的椭圆方程的解: 按照 PDE 的要求,将方程化为标准形式 求解后的图像如下,第一幅图是解的图像,第二幅是计算误差。从第二幅图可以看到,计算的最大误差是10 -3 方量级。 通过这个例子我们可以基本掌握 PDE 求解偏微分方程的步骤和方法,后面我将详细介绍如何设置区域及边界条件。掌握了区域和边界条件的设定,就可以轻松求解遇到的偏微分方程了。 图后是附带的matlab命令以及注释,并提供m文件附件下载,下载后解压即可。希望能对大家有所帮助。 下面是编写的求解上述方程的 matlab语句 及说明: g='mygeom'; b='mybound'; 定义区域,边界条件。 mygeom 是定义区域的子函数名,函数名可根据自己的 需要取定,区域的确定规则由 pdegeom 函数说明,注意 pdegeom 函数只是说 明如何定义区域,它并不直接确定区域; mybound 是定义边界条件的子函数 名,与区域类似,边界的确定规则由函数 pdebound 确定。后面我会详细介绍 区域和边界的取法。 = initmesh(g); 网格初始化,此处也可以写成 =initmesh('mygeom'); 这样可以省略上面的 语句 = refinemesh(g,p,e,t); = refinemesh(g,p,e,t); 加密网格两次,需要加密几次重复几次即可,根据具体问题确定加密次数 U= assempde(b,p,e,t,1,0,'2*(x+y)-4'); 调用 assempde 函数计算方程的数值解, assempde 函数的详细用法可以参考 MATH 网站或者 PDE 的使用指南。常用的用法是 =assempde(b,p,e,t,c,a,f) ,其中 b 为边界条件,此处也可以写为 'mybound' , p,e,t ,为网格参数, c,a,f ,为方程的参数,后面也可以加猜测值以及各种属性。 pdesurf(p,t,U) grid on; xlabel('x');ylabel('y');zlabel('u') colorbar view( ) 画出解的图形。 注意,为了让结果更直观一些,使用 view 函数 调整了视点位 置。大家可以自行调整视角,满意即可。 exact=p(1,:).^2+p(2,:).^2-p(1,:).*p(2,:).*(p(1,:)+p(2,:)); exact=exact'; figure pdesurf(p,t,U-exact) grid on xlabel('x');ylabel('y');zlabel('error') colorbar view( ) 由于方程有解析解,我们可以比较数值计算的误差。如果能求得解析解,我 们也不会设计各种方法求数值解了,因此,这一步在大多数情况下是用不上 的,这里只是为了比较计算结果,验证计算的精度。 m文件下载
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明年4月英国剑桥牛顿数学研究所的一个学术会议
伍渝江 2010-8-17 23:47
明年4月4-8日,英国剑桥的 Isaac Newton 数学科学研究所和威尔士的数学与计算科学研究所(WIMCS)将联合在Swansea大学举办一个 PDE计算挑战的学术会议。具体信息如下: ---------------------------------------------------------------------------------------------------------------------- INI/WIMCS MEETING 2011 In April 2011, the Isaac Newton Institute for Mathematical Sciences (INI), Cambridge,and the Wales Instituteof Mathematical and Computational Sciences (WIMCS) will jointly organise a meeting on Computational Challenges in Partial Differential Equations at Swansea University. The meeting will start on Monday, April 4th and end on Friday, April 8th. This will be a follow-up meeting which, hopefully, will build upon the success of the six-month research programme, of the same name , that was held at the INI in 2003. Financial support for the meeting has been provided by the INI , WIMCS and the Centre for Numerical Analysis and Intelligent Software (NAIS). ORGANISERS The scientific organisers of the meeting are: Mark Ainsworth, University of Strathclyde Charles M. Elliott, University of Warwick Kenneth Morgan, Swansea University Endre Sli, University of Oxford MEETING FORMAT The meeting will consist of eight half-day sessions, each concentrating on a particular research area that is currently attracting significant interest within the community. The sessions will address the following themes: Multiscale modelling Interface modelling PDEs on surfaces and geometric evolution problems Biomedical applications, including new modelling techniques and patient-specific applications Computational rheology Atomistic-to-continuum passage, density functional theory and quasi-continuum methods Low order modelling: widening the range of high-fidelity time-dependent simulations Uncertainty modelling SPEAKERS Each half-day session will consist of invited presentations by four leading scientists. The following have agreed to participate and make presentations: A. Abdulle, EPFL, Switzerland S. Adhikari, Swansea University, UK J. W. Barrett, Imperial College London, UK S. Bartels, Universitt Bonn, Germany E. Cancs, CERMICS-ENPC, France S. J. Cox, Aberystwyth University, UK K. Deckelnick, Otto-von-Guericke-Universitt, Magdeburg, Germany Q. Du, Pennsylvania State University, USA G. Dziuk, Universitt Freiburg, Germany R. S. Elliott, University of Minnesota, USA C. Farhat, Stanford University, USA L. Formaggia, Politecnico di Milano, Italy T. Y. Hou, Caltech, USA G. E. Karniadakis, Brown University, USA C. Le Bris, CERMICS-ENPC, France T. Lelivre, CERMICS-ENPC, France P. Lin, University of Dundee, UK J. S. Lowengrub, UC Irvine, USA Y. Maday, Universit Pierre et Marie Curie, France K. Miller, The University of Western Australia, Australia G. S. Mishuris, Aberystwyth University, UK P. Nithiarasu, Swansea University, UK C. Ortner, University of Oxford, UK A. T. Patera, MIT, USA J. Peraire, MIT, USA D. Peric, Swansea University, UK T. N. Phillips, Cardiff University, UK W. Ren, Courant Institute, USA G. Rozza, EPFL, Switzerland S. Ruuth, Simon Fraser University, Canada S. Sherwin, Imperial College London, UK B. Stinner, University of Warwick, UK PROGRAMME An outline version of the programme has been prepared. This will be updated as more information becomes available. LOCATION The meeting will be held on the campus of Swansea University, in theFaraday Building. The location of this buildingis clearly marked on the campus map . Swanseacan be reached by road or by direct train service from London. The nearestmajor airport is Cardiff , with international connections via Amsterdam and Paris. REGISTRATION FEES The registration fee is 155. This covers attendance at the sessions, the welcome drinks reception on April 4th and the special dinner on April 7th. The costs of morning coffee, afternoon tea and lunches, for each day, are also included. To register, please complete and return the registration form . ACCOMMODATION A limited number of en-suite rooms, in student campus accommodation, are available. To reserve accommodation, please complete and return the accommodation form . CONTACT DETAILS Please address queries forfurther informationto k.morgan@swansea.ac.uk
个人分类: 学海泛舟|4860 次阅读|0 个评论
老药物,新用途 ——万艾可那些有爱的副作用
songshuhui 2010-6-12 00:07
游识猷 发表于 2010-06-10 12:48 研究者们近来发现,广受欢迎的药物万艾可(又名伟哥、威尔刚、Viagra)又有了最新的一种功能,而且这项功能将来很可能对女性大有裨益读到这里先别急着露出心领神会的神秘微笑,这项功能大约和你心中所浮现的猜想不太一样。 倒不是说辉瑞制药(Pfizer)没和您打过同一个主意,但是很不幸地,万艾可在广大女性受众那里的实验效果实在一般。至于为什么在男性身上神奇无比的蓝色小药丸到女性那里就不管用了呢? 有人说,原因如下图所示。 这当然只是个玩笑。不过一心想攻下女性市场的辉瑞可笑不出来,他们最后只好转向开发与万艾可作用机理完全不同的药物。最新的进展是一种叫UK-414495的药物,刚在兔子身上做了实验。实验据说很成功 ,虽然出现了一些和研究本身质量无关的不太和谐的评论 兔子!难道你觉得它们生得还不够多么? 外国的野兔泛滥起来确实让他们头痛不已,好像兔子多得他们都不知该拿它们怎么办了。前不久,瑞典干脆把野兔塞锅炉里当柴火烧来供暖。 西方国家之所以会有这种何不烧肉糜的烦恼,在我看来,还是我泱泱天朝的各种兔肉食谱没有得到足够推广的缘故。 离题了,打住,回来正题。研究者们究竟发现万艾可能给女性同胞带来什么福音呢? 辅助治疗肿瘤。 对,您没看错,您眼神好着呢,就是辅助治疗肿瘤。 要说万艾可的这种功能,其实最早算是它的副作用之一。 有人不信了,还能有这么好的副作用?简直比正作用还彪悍了。 其实想当年,万艾可这个药最初的作用也不是造福男性,它这个现在的主要疗效当初的副作用,也是这么东方不亮西方亮地被人发现的。 当年辉瑞一帮子人窝在英国肯特郡的三明治小镇(Sandwich, Kent)里,研究这个代号叫UK-92480的药物时,原本是打算拿它来控制血压和治疗心绞痛的。 当在英国进行临床试验时,辉瑞发觉,虽然临床数据证明这药控制血压的效果那是相当的一般,可是这药在男性参与者中却是出乎意料地受欢迎,自愿报名入实验组的人潮简直是挡也挡不住 辉瑞立刻意识到,一个大馅饼砸到他们头上了。 不过,为什么一个设计来控制血压的药能有那么不可思议的副作用呢?这就得从万艾可的作用机理说起。 我们的身体是一个非常精密的系统,有着各种调控机制来令人体能更好地利用自己的资源,有时这些机制可说是精巧不已。例如,我们的血液总量就那么多,当一个人运动的时候,他可能希望血液能更多地流向自己的肺部和四肢;当他考试的时候,恨不得大部分的血液都涌向大脑,让他能灵感如泉涌;而当他吃饭的时候,他又需要血液更多的流向自己的胃肠,以帮助胃肠更好地吸收养分。当他看到一个美女双眼为之一亮的时候,他就需要血液流向该去的地方 可是我们的血流动力来源就那么一颗心脏,这颗泵怎么才能在自己单调的一张一弛间实现那么多复杂的调控呢? 来自心脏的动力是统一的改不了,要不这样,我改局部的阻力还不行吗? 于是乎这时候我们的血管就来帮忙了。 别看血管细,那血管壁还分了内中外三层,中间那层叫中膜的有许多平滑肌细胞,那就是我们要重点介绍的能缩能伸的主角。 血管中膜里的平滑肌细胞平常维持在收缩状态,这时候血管也比较收窄,意味着阻力比较大,流入的血液量相对少一些。当需要增加某处血液流量时,从脑部发出的信号顺着神经纤维到达那处血管里的非肾上腺非胆碱能(NANC)神经细胞,这种细胞于是释放出一氧化氮(NO)作为神经递质到自身周围,一氧化氮就是传令兵一号,它去找下线传达信息,下线是谁呢?原来周围的细胞里面有一种蛋白酶,叫鸟苷酸环化酶(guanylate cyclase),这种酶一看,一氧化氮来了,噢,该干活了,就开始制造环单磷酸鸟酐(cyclic guanosine monophosphate),简称cGMP的一个分子。cGMP功能很多,不过在这个系统里,它就是传令兵二号,它被制造出来以后就去找平滑肌细胞传达上面的最新指示:别绷着,放松点。平滑肌细胞收到这讯息,就慢慢松弛拉长,整个血管也随之舒张,那里的血液流量自然也就增加了。 有人就琢磨了,那要是我又想收窄血管了怎么办? 不难。其实啊,这整套机制里,还有个重点人物没出场呢。 这号人物叫磷酸二酯酶(phosphodiesterase),简称PDE。PDE属于潜伏在那儿专门破坏革命队伍的角色,一看到cGMP就把他拉到一边,转化为三磷酸鸟苷(GTP)。当脑部传来信号时,cGMP就被源源不断地制造出来,平滑肌细胞也因而保持拉长的状态。但当脑部不再传来信号时,cGMP就只有消耗没有产出,原本留下的传令兵再多也经不起PDE这么持续和平演变啊。cGMP一消耗殆尽,平滑肌细胞收不到信号了,就又回复原本的收缩状态,于是血管变窄,血液流量下降到原始水平。 所以这出名为血流调控的戏剧里,正面角色包括一氧化氮和cGMP,这俩都是能增加血液流量的分子。反派就是PDE,这小子不干好事,专拖cGMP的后腿。这么一总结我们就清楚了,要增加某处的血液供应,一种办法是增加干活的人手,另一种办法就是减少拖后腿的。 万艾可采用的就是后一种办法。 有人又琢磨了,你说万艾可一个口服药,吃下去以后药物被吸收,然后随着血液流动运输到全身,你说它怎么就能针对性地对某重点部位的PDE进行裁员呢?要是它先从肠胃的PDE下手,那不成了助消化药了吗? 原来我们体内的PDE其实是一大类,就目前所知,至少有十一种PDE分布在人体各部位,其中PDE5就主要分布在那个重点区域。知道这点以后,万艾可的发明就变得顺理成章了,辉瑞发现这个学名叫枸橼酸西地那非(sildenafil citrate)的东西结构上恰好和PDE5十分契合,它跟PDE5一块儿的时候,借用一句歌词,那就是你是风儿我是沙缠缠绵绵到天涯,PDE5忙起来就没功夫搭理cGMP了,于是cGMP就能不断累积,于是那儿的血流量就越来越增加,于是局部不断充血,于是于是辉瑞就有了一只会下金蛋的母鸡。 万艾可大获成功之后,其他制药公司眼都红了。要说确实原理弄清楚以后,类似的PDE5抑制物其实没那么难研制。于是,礼来公司(Eli Lilly and Company)做了个Tadalafil(商品名Cialis);拜耳(Bayer Pharmaceuticals)、葛兰素史克(GlaxoSmithKline)再加上先灵葆雅(Schering-Plough)三家联合推出了vardenafil(商品名Levitra);都急吼吼地冲来分一杯羹。 实际上,vardenafil才是这次研究者实验中更多地使用的药物。可惜vardenafil的名气实在差万艾可一大截,结果许多新闻媒体报导时,还是打着万艾可的招牌报导。不知三巨头看到那些报道时候,会不会仰天吐一口血,叹一句既生瑜何生亮。 言归正传,还是回来接着说万艾可到底怎么能辅助肿瘤治疗吧。 我们前面提到了万艾可的主要作用对象是PDE5,而且说了,PDE5主要分布在某重点区域。 主要二字,就代表别处也是有一点PDE5的。 比如说,脑子里。 因此,一个人服用万艾可以后,脑部的PDE5也会受到抑制,结果就是脑部的cGMP相对增多了。 cGMP这个传令兵比较十项全能,除了放松血管平滑肌以外,它还能控制离子通道、细胞凋亡、肝糖分解、眼部光传递系统等等等等,不一而足。 这就带来了万艾可的一些副作用有的人抱怨服用以后头痛,有的人则表示视觉受到影响,比如整个世界都有点偏色,确切地说,偏蓝一点。这其实就代表了万艾可对脑部眼部都有影响力。 此外,因为脑部的cGMP还能辅助记忆形成的过程,2006年美国国家卫生院(National Institutes of Health)的研究员就证实了万艾可能让老鼠在迷宫里认路认得快点基本上,这就代表了学习能力和记忆力的提高。 万艾可对脑部的这些副作用倒是让研究人员想起了一个困扰他们已久的事儿脑部肿瘤的给药问题。 我们的大脑可说是全身最重要的器官,因此我们也进化出一整套最为严密谨慎地保护着它的机制。这套机制中,就包括血脑屏障(blood brain barrier,BBB)。简单说来,就是比起全身其他组织器官的毛细血管,脑部的毛细血管结构上尤为紧密,大多数物质无法通过脑部的毛细血管壁进入脑组织。很容易想见,这样做可以保护大脑免受许多伤害。 但当脑部出现肿瘤时,或者当别处的肿瘤转移到脑部时,这样的肿瘤就也受到了类似结构的保护,称为血脑肿瘤屏障(blood-brain tumor barrier ,BTB)。 有些肿瘤明明对化疗药物非常敏感,比如HER2检测呈阳性的乳癌就对单克隆抗体赫赛汀(Herceptin)有着很好的反应。但当这种乳癌转移到脑部以后,赫赛汀因为难以通过血脑肿瘤屏障,就很难抵达脑部的转移灶加以控制。 自然母亲创造出这个屏障是为了保护我们的大脑远离各种危险物质,但现在我们需要穿透屏障给药时,却遇到了麻烦。主要研究者之一,Maxine Dunitz神经外科研究所的Julia Y Ljubimova博士如是说。 所以,你应该能想见当研究者们发现口服万艾可居然能增加血脑肿瘤屏障的渗透性时他们能有多高兴。 在最初的实验中,万艾可把血脑肿瘤屏障的渗透性增加了1.8倍,而三巨头推出的vardenafil则提高了2.7倍。实验人员于是选定vardenafil做为后续实验的用药。随后,实验人员培养出身上种植有人类肺癌和乳癌细胞的小鼠,确定它们都有脑部转移后,把它们随机分成四组给药,一组给盐水,一组单给赫赛汀,一组单给vardenafil,最后一组则同时给赫赛汀与vardenafil两种药。结果显示,同时给予赫赛汀和vardenafil的小鼠在生存时间上比起其余三组有了明显提高肺癌组延长了30%,而乳癌组延长了20%。 Ljubimova博士对此结果当然非常满意,我们现在已经展示了如何让大分子透过血脑肿瘤屏障,以后我们会继续对纳米医学里的更多大分子药物采用这种策略,这将为脑部肿瘤的治疗开启一个全新的世界。 万艾可帮忙治脑瘤,这确实是一个崭新的世界。 传说里,这一把蓝色小药丸还有更多匪夷所思的非主流作用帮助球队获胜、拯救濒危动物、解决粮食危机,以及,帮助CIA反恐 如有好奇的读者想知道有关具体情形,不妨移步最后一条参考资料的网址,自行观赏、惊叹、赞美、铭记之。 【完】 参考资料 C.P. Wayman, D. Baxter, L. Turner, P.H. Van Der Graaf and A.M. Naylor; UK-414,495, a selective inhibitor of neutral endopeptidase, potentiates pelvic nerve-stimulated increases in female genital blood flow in the anaesthetized rabbit; British Journal of Pharmacology 2010; Volume 160 Issue 1, Pages 51 59 http://www.time.com/time/specials/packages/article/0,28804,1945379_1944626,00.html http://en.wikipedia.org/wiki/Sildenafil http://health.howstuffworks.com/viagra3.htm http://en.wikipedia.org/wiki/Cyclic_guanosine_monophosphate Phosphodiesterase inhibition by sildenafil citrate attenuates a maze learning impairment in rats induced by nitric oxide synthase inhibition Psychopharmacology (Berl). 2006 Jan;183(4):439-45. http://www.eurekalert.org/pub_releases/2010-05/cmc-dnu050710.php Hu J, Ljubimova JY, Inoue S, Konda B, Patil R, et al. (2010) Phosphodiesterase Type 5 Inhibitors Increase Herceptin Transport and Treatment Efficacy in Mouse Metastatic Brain Tumor Models. PLoS ONE 5(4): e10108. doi:10.1371/journal.pone.0010108 http://jandan.net/2010/03/29/5-weird-uses-of-viagra.html 扩展阅读: 吃伟哥可能有听力损失风险? 小药片 性安全 万艾可为什么是蓝色的 ? 万艾可问题 :Zeng Amy(附众答案)
个人分类: 医学|2838 次阅读|0 个评论
Notes on Partial Differential Equations(John K. Hunter)
热度 1 ChinaAbel 2010-4-11 20:52
Abstract. These are notes from a two-quarter class on PDEs that are heavily based on the book Partial Differential Equations by L. C. Evans, together with other sources that are mostly listed in the Bibliography. The notes cover roughly Chapter 2 and Chapters 5--7 in Evans. There is no claim to any originality in the notes, but I hope for some readers at least they will provide a useful supplement. Notes on Partial Differential Equations ( John K.Hunter ).pdf Notes on Partial Differential Equations ( John K.Hunter ).pdf Measure Theory ( John K. Hunter ).pdf
个人分类: 电子图书(仅限学术研究使用,禁止商业用途)|6033 次阅读|1 个评论
Variational Methods for PDE
ChinaAbel 2009-1-14 22:36
1. Variational Problems in SBV . 2. Critical Point Theorems and Applications to Nonlinear Differential Equations 3. Critical Exponents and Dimensions for Elliptic Equations 4. Variational Problems in the Space of Functions of Bounded Variation 5. Variational Techniques for Sturm-Liouville Eigenvalue problem 6. Variational Inequalities of Elliptic and Parabolic Type 7. Variational Methods for k-Hessian Equations 8. A local minimax-newton's method for finding critical points with symmetries 9. Lusternik-Schnirelman theory in partially ordered ordered Hilbert spaces
个人分类: 电子图书(仅限学术研究使用,禁止商业用途)|299 次阅读|0 个评论
The Notes for PDE and Harmonic Analysis
ChinaAbel 2008-12-19 22:35
1. Notes on the p-Laplace equation . 2. Topics in Harmonic Analysis . 3. Lecures on Lipschitz analysis . 4. Nonlinear potential theory on metric spaces . 5. The Obstacle Problem . 6. Lectures on Regularity of free boundaries in Obstacle-type 7. Heat Method in Nonlinear Elliptic Equations
个人分类: 电子图书(仅限学术研究使用,禁止商业用途)|522 次阅读|0 个评论
一些早期的文献Variational Methods for PDE
ChinaAbel 2008-12-19 10:18
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