A NOTE ON GLOBAL ATTRACTIVITY OF THE MODEL FOR THE SURVIVAL OF THE RED BLOOD CEELS WITH SEVERAL DELAYS

1 IntroductionConsider the red blood ceels growth model with several delayswhere r(t) E C([0, oo), (0, oo)), Pil ri) n e (0, oo), and r1 2 r2 2'' 2 rm.Eq.(l) was used first by Wazewska-Czyzewska and Lasota [l] as a model forthe survival of the red blood ceels in an animal, see also Arino and Kimmel[2]. There are a lot of activities concerning the asymptotic behavior of (1),see for examp1e [3] and the references cited therein. The following results wasobtained in [l, 3, 4].N'(t) = --pN(t)…     

Enumerating rooted simple planar maps

The main purpose of this paper is to find the number of combinatorially distinct rooted simpleplanar maps,i.e.,maps having no loops and no multi-edges,with the edge number given.We haveobtained the following results.1.The number of rooted boundary loopless planar [m,2]-maps.i.e.,maps in which there areno loops on the boundaries of the outer faces,and the edge number is m,the number of edges on theouter face boundaries is 2,is(?)for m≥1.G_0~N=0.2.The number of rooted loopless planar [m,2]-maps is(?)3.The number of rooted simple planar maps with m edges H_m~s satisfies the following recursiveformula:(?)where H_m~(NL) is the number of rooted loopless planar maps with m edges given in [2].4.In addition,γ(i,m),i≥1,are determined by(?)for m≥i.γ(i,j)=0,when i>j.     

一类替换环的偏序$K_{0}$-群的无扭性

A ring R is called orthogonal if for any two idempotents e and f in R, the condition that e and f are orthogonal in R implies the condition that [eR] and [fR] are orthogonal in K0（R）^＋, i.e., [eR]∧[fR] = 0. In this paper, we shall prove that the K0-group of every orthogonal, IBN2 exchange ring is always torsion-free, which generalizes the main result in [3].     

ON ThE OPTIMUM MASS RATIOS OF STEP-ROCKETS

In this paper, the writer will give a concrete counter-example to show that an important argument in [1]and [2](i. e. in this problem the extreme-point and the optimum mass Rat ios were the same) was Somewhat incorrect in general.Then how to find the optimum mass Ratios in Reneral situation? To do this, The writer went a step further to discuss the work of [1], [2], and obtained not only some important new results such as the existance and uniqueness of the extreme-points in[2], but also proposed the idea of theoretical permissible region as well as the idea of practical permissible region etc. Then proposed a method for determining the optimum mass Ratios, Hence some results in [1] and[2] were improved and perfected.     

关于Gauss过程增量的若干结果

Let {X(t);t≥0}be a Gaussian process with stationary increments,X(0)=0(a.s.),EX(t)=0 andσ~2(h)=EX(t+h)-X(t)~=EZ~2(h)=Coh~(2α),0<α≤1.In this paper,we first prove that the Levy's theorem of the modulus of continuityof the Wiener process is also true for {X(t);t≥0};i.e.Furthermore,we point out that some results on increments of the Wiener processesin[3]and[4]remain true for the increments of {X(t);t≥0}.     

Density of Integers That Are the Sum of Four Cubes of Primes

gi. IntroductionIt is conjectured that all sufficielltly large integers e satisfying some necessaly congruenceconditions are the sum of four cubes of primes, i.e.(see e.g. [1]). Such a strong conjecture is out of reach at present; but it is reasonable, inview of the following results of Hua and Davenport respectively. A theorem of Hua[3'4] statesthst almost all positive integers, with t * 0, 12(mod 9) are the sum of five cubes of praies,while DavenPOrt's result in 12] asserts that almost all…     

控制调幅波耗散方程的整体吸引子的有限维

§ 1　IntroductionIn this paperwe shall study successively the equationsgiven in [1 ,2 ] .Underthe sameconditions(i.e.the initial boundary value and other conditions) as in[1 ,2 ] ,the upperbound of the dimension of their global attractor will be obtained respectively.Theexistence of the global attractors have been proved in[1 ,2 ] .This paper is organized as follows:In§ 2 ,we derive the Frechet differential of the solution operator s(t) for theperturbed system.In§ 3 ,we show the finite di…     

On the Radius of Analyticity of Solutions to 3D Navier-Stokes System with Initial Data in Lp

Given initial data u₀ ∈ L^p(R³) for some p in[3, 18/5[, the auhtors ?rst prove that 3D incompressible Navier-Stokes system has a unique solution u = uL+v with uL def = et^?u0 and v ∈ e L^∞([0, T]; ˙ H^{5/2 ? 6/p} ) ∩ L¹(]0, T[; ˙H^{9/2 ? 6/p} ) for some positive time T. Then they derive an explicit lower bound for the radius of space analyticity of v, which in particular extends the corresponding results in [Chemin, J.-Y., Gallagher, I. and Zhang, P., On the radius of analyticity of solutions to semi-linear parabolic system, Math. Res. Lett., 27, 2020, 1631– 1643, Herbst, I. and Skibsted, E., Analyticity estimates for the Navier-Stokes equations, Adv. in Math., 228, 2011, 1990–2033] with initial data in ˙H^s(R³) for s∈[1/2,3/2[.     

ON THE SENSITIVITY OF THE LDU FACTORIZATION

1　IntroductionG.W.Stewart,X.-W.Chang and A.Barralund etc.have done lot of perturbationanalyses on LU,QR and Cholesky factorizations( see[5] ,[6] ,[1 ] ,[2 ] ,[4 ] ,[3 ] ) .We givesensitivity analysisfor LDU factorization in this paper.The LDU factorization ( or LDMT) is an important method in numerical linear algebra( see [7] ) ,and can be viewed as the general form for LDLT factorization. The differencebetween LDU and LU factorizations in upper triangular matrix U,i.e. U is uni…     

Two Theorems on Volume and Dihedral Angles of a n—dimensional Simplex

In this paper,we obtain thorem 1 on volum of a n-dimensional simplex and theorem 2 on dihedral angles of a simplex.Besides.We obtain Vasic inequality in E^n and its extension.The results in this paper contain and improve the results in paper[1]、[2]、[3]、[4].