Multilevelverfahren für nichtlineare Finite-Element Ausgleichsprobleme

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A Least Squares Mixed Finite Element Method For

For the coupling of ow and deformation in variably saturated porous media we propose a mixed nite element method based on a least-squares principle. This approach is motivated by the fact that all process variables, i.e., hydraulic potential and uid ux as well as displacement eld and stress tensor, are approximated directly by suitable nite element spaces. For the ow model we consider both fully saturated and variably saturated porous media. The deformation is assumed to be linearly elastic. Our approach combines a least-squares approach for variably saturated subsurface ow with a recently developed least-squares formulation for linear elasticity. Standard -conforming piecewise linear and quadratic nite elements are used for the hydraulic potential and for (each component of) the displacement, respectively. For the ux and stress components, the H(div)-conforming Raviart-Thomas spaces (of lowest order) are used. Computational results are presented for some test problems including two-dimensional fully saturated and one-dimensional variably saturated problems

Numerical Approximation of Water-Air Two-Phase Flow By The . . .

A new model for two-phase flow of water and air in soil is presented. This leads to a system of two mass balance equations and two equations representing conservation of momentum of fluid and gas, respectively. This paper is concerned with the verification of this model for the special case of a rigid soil skeleton by computational experiments. Its numerical treatment is based on the Raviart-Thomas mixed finite element method combined with an implicit Euler time discretization. The feasibility of the method is illustrated for some test examples of one- and two-dimensional two-phase flow problems

Developmental competence and mRNA expression of preimplantation in vitro-produced embryos from prepubertal and postpubertal cattle and their relationship with apoptosis after intraovarian administration of IGF-1.

Recombinant human Insulin-like growth factor-I (hIGF-1) was administered to one ovary of prepubertal and postpubertal cattle to determine its effects on (1) oocyte developmental competence, (2) the expression pattern of six developmentally important genes (GLUT3, GLUT8, AKT1, BCL-XL, BAD, and BAX), and (3) its relationship with apoptosis (female Holstein-Friesian). Oocytes were retrieved from 7- to 10-mo-old prepubertal dairy calves (preP), 11- to 18-mo-old postpubertal heifers (postP), and cows via ultrasound-guided follicular aspiration. Immature oocytes were matured in vitro then fertilized and cultured up to the blastocyst stage. Apoptosis was determined by terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) in 8-d blastocysts. Similar low blastocyst yields were observed in the IGF-1-treated preP group (11.2+/-2.4%), the control preP group (10.4+/-3.0%), and in the IGF-1 postP group (10.9+/-2.3%). These were lower (P<or=0.01) compared with the control postP group (21.2+/-3.8%) and with cows (23+/-3.7%). The expression profile of the six genes was partly affected by age and IGF-1 treatment. Apoptosis was correlated with the age of the oocyte donors and was increased in blastocysts derived from prepubertal heifers. Results show that apoptosis is a critical feature of the acquisition of developmental competence of oocytes from prepubertal cattle and that IGF-1 did not beneficially affect oocyte developmental competence