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Search Results: 1 - 10 of 3643 matches for " Jens Grosche "
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Response of sinusoidal mouse liver cells to choline-deficient ethionine-supplemented diet
Elke Ueberham, Jan B?ttger, Uwe Ueberham, Jens Grosche, Rolf Gebhardt
Comparative Hepatology , 2010, DOI: 10.1186/1476-5926-9-8
Abstract: CDE diet leads to an activation of all cells of the hepatic sinusoid in the mouse liver. Beside oval cells, also HSCs and Kupffer cells proliferate. The entire fraction of proliferating cells in mouse liver as well as endothelial cells and cholangiocytes express M2-pyruvate kinase. Concomitantly, GFAP, long considered a unique marker of quiescent HSCs was upregulated in activated HSCs and expressed also in cholangiocytes and oval cells.Our results point to an important role of all types of sinusoidal cells in regeneration from CDE induced liver damage and call for utmost caution in using traditional marker for identifying specific cell types. Thus, M2-pyruvate kinase should no longer be used for estimating the oval cell response in mouse liver. CDE diet leads to activation of GFAP positive HSCs in the pericentral zone of liver lobulus. In the periportal zone the detection of GFAP in biliary cells and oval cells, calls other cell types as progenitors of hepatocytes into question under CDE diet conditions.Oval cell reaction occurs under pathological conditions in human liver and in early stages of experimental hepatocarcinogenesis protocols in rodents provided hepatocyte proliferation is impaired. A frequently used protocol applies ethionine, the ethyl analogon of methionine, together with a choline deficient diet (CDE) [1]. During CDE diet many metabolic changes in hepatocytes take place leading to deposition of lipids in hepatocytes and massive lethal deterioration of this cell type. Surviving hepatocytes are no longer able to proliferate and to repopulate the damaged tissue. Instead, oval cells, the bipotential progenitor cells of liver that are resistant against the destroying mechanisms, are activated and enrich. For proliferation they require a typical microenvironment which is provided by cells of the hepatic sinusoids closely adjacent to them. The pivotal role of an intrahepatic inflammatory response in this process, and the recruitment of Kupffer cells and ot
Effects of Direct Instruction in Reading Accuracy
Michael Grosche
Empirische Sonderp?dagogik , 2011,
Abstract: Despite tremendous societal relevance and high prevalence of functional illiteracy in Germany, it is unknown which basic education methods in reading instruction are effective with adults. Consequently, the present multiple baseline study with three adult struggling readers evaluates a direct instruction approach in reading accuracy. Due to low rates of learning, results are somewhat inconsistent. Namely, learners only partially increased their reading skills, there was limited generalizability of learning, and a temporarily decline in reading skills. This pattern could be explained by specific learning barriers of functionally illiterate adults. Limitations of the study and societal implications are discussed.
Path Integration and Separation of Variables in Spaces of Constant Curvature in Two and Three Dimensions
Christian Grosche
Physics , 1993, DOI: 10.1002/prop.2190420602
Abstract: In this paper path integration in two- and three-dimensional spaces of constant curvature is discussed: i.e.\ the flat spaces $\bbbr^2$ and $\bbbr^3$, the two- and three-dimensional sphere and the two- and three dimensional pseudosphere. The Laplace operator in these spaces admits separation of variables in various coordinate systems. In all these coordinate systems the path integral formulation will be stated, however in most of them an explicit solution in terms of the spectral expansion can be given only on a formal level. What can be stated in all cases, are the propagator and the corresponding Green function, respectively, depending on the invariant distance which is a coordinate independent quantity. This property gives rise to numerous identities connecting the corresponding path integral representations and propagators in various coordinate systems with each other.
Path Integral Representations on the Complex Sphere
Christian Grosche
Physics , 2007,
Abstract: In this paper we discuss the path integral representations for the coordinate systems on the complex sphere S3C. The Schroedinger equation, respectively the path integral, separates in exactly 21 orthogonal coordinate systems. We enumerate these coordinate systems and we are able to present the path integral representations explicitly in the majority of the cases. In each solution the expansion into the wave-functions is stated. Also, the kernel and the corresponding Green function can be stated in closed form in terms of the invariant distance on the sphere, respectively on the hyperboloid.
Path Integration Via Summation of Perturbation Expansions and Applications to Totally Reflecting Boundaries, and Potential Steps
Christian Grosche
Physics , 1993, DOI: 10.1103/PhysRevLett.71.1
Abstract: The path integral for the propagator is expanded into a perturbation series, which can be exactly summed in the case of $\delta$-function perturbations giving a closed expression for the (energy-dependent) Green function. Making the strength of the $\delta$-function perturbation infinite repulsive, produces a totally reflecting boundary, hence giving a path integral solution in half-spaces in terms of the corresponding Green function. The example of the Wood-Saxon potential serves by an appropriate limiting procedure to obtain the Green function for the step-potential and the finite potential-well in the half-space, respectively.
Selberg Supertrace Formula for Super Riemann Surfaces III: Bordered Super Riemann Surfaces
Christian Grosche
Physics , 1993, DOI: 10.1007/BF02101748
Abstract: This paper is the third in a sequel to develop a super-analogue of the classical Selberg trace formula, the Selberg supertrace formula. It deals with bordered super Riemann surfaces. The theory of bordered super Riemann surfaces is outlined, and the corresponding Selberg supertrace formula is developed. The analytic properties of the Selberg super zeta-functions on bordered super Riemann surfaces are discussed, and super-determinants of Dirac-Laplace operators on bordered super Riemann surfaces are calculated in terms of Selberg super zeta-functions.
Path Integral Solution of a Class of Explicitly Time-Dependent Potentials
Christian Grosche
Physics , 1993, DOI: 10.1016/0375-9601(93)90048-5
Abstract: A specific class of explicitly time-dependent potentials is studied by means of path integrals. For this purpose a general formalism to treat explicitly time-dependent space-time transformations in path integrals is sketched. An explicit time-dependent model under consideration is of the form $V(q,t)=V[q/\zeta(t)]/\zeta^2(t)$, where $V$ is a usual potential, and $\zeta(t)=(at^2+2bt+c)^{1/2}$. A recent result of Dodonov et al.\ for calculating corresponding propagators is incorporated into the path integral formalism by performing a space-time transformation. Some examples illustrate the formalism.
An Introduction into the Feynman Path Integral
Christian Grosche
Physics , 1993,
Abstract: In this lecture a short introduction is given into the theory of the Feynman path integral in quantum mechanics. The general formulation in Riemann spaces will be given based on the Weyl- ordering prescription, respectively product ordering prescription, in the quantum Hamiltonian. Also, the theory of space-time transformations and separation of variables will be outlined. As elementary examples I discuss the usual harmonic oscillator, the radial harmonic oscillator, and the Coulomb potential. Lecture given at the graduate college ''Quantenfeldtheorie und deren Anwendung in der Elementarteilchen- und Festk\"orperphysik'', Universit\"at Leipzig, 16-26 November 1992.
$δ$-Function Perturbations and Boundary Problems by Path Integration
Christian Grosche
Physics , 1993, DOI: 10.1002/andp.19935050606
Abstract: A wide class of boundary problems in quantum mechanics is discussed by using path integrals. This includes motion in half-spaces, radial boxes, rings, and moving boundaries. As a preparation the formalism for the incorporation of $\delta$-function perturbations is outlined, which includes the discussion of multiple $\delta$-function perturbations, $\delta$-function perturbations along perpendicular lines and planes, and moving $\delta$-function perturbations. The limiting process, where the strength of the $\delta$-function perturbations gets infinite repulsive, has the effect of producing impenetrable walls at the locations of the $\delta$-function perturbations, i.e.\ a consistent description for boundary problems with Dirichlet boundary-condition emerges. Several examples illustrate the formalism.
Path Integral Approach for for Quantum Motion on Spaces of Non-constant Curvature According to Koenigs: Three Dimensions
Christian Grosche
Physics , 2007,
Abstract: In this contribution a path integral approach for the quantum motion on three-dimensional spaces according to Koenigs, for short``Koenigs-Spaces'', is discussed. Their construction is simple: One takes a Hamiltonian from three-dimensional flat space and divides it by a three-dimensional superintegrable potential. Such superintegrable potentials will be the isotropic singular oscillator, the Holt-potential, the Coulomb potential, or two centrifugal potentials, respectively. In all cases a non-trivial space of non-constant curvature is generated. In order to obtain a proper quantum theory a curvature term has to be incorporated into the quantum Hamiltonian. For possible bound-state solutions we find equations up to twelfth order in the energy E.
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