1,391 research outputs found
Recycling probability and dynamical properties of germinal center reactions
We introduce a new model for the dynamics of centroblasts and centrocytes in
a germinal center. The model reduces the germinal center reaction to the
elements considered as essential and embeds proliferation of centroblasts,
point mutations of the corresponding antibody types represented in a shape
space, differentiation to centrocytes, selection with respect to initial
antigens, differentiation of positively selected centrocytes to plasma or
memory cells and recycling of centrocytes to centroblasts. We use exclusively
parameters with a direct biological interpretation such that, once determined
by experimental data, the model gains predictive power. Based on the experiment
of Han et al. (1995b) we predict that a high rate of recycling of centrocytes
to centroblasts is necessary for the germinal center reaction to work reliably.
Furthermore, we find a delayed start of the production of plasma and memory
cells with respect to the start of point mutations, which turns out to be
necessary for the optimization process during the germinal center reaction. The
dependence of the germinal center reaction on the recycling probability is
analyzed.Comment: 30 pages, 8 figure
Equivariant Deformations of Horospherical Surfaces
The classical Goursat transform for minimal surfaces is interpreted as conformal transformation of the Gauss map, allowing us to bend these surfaces for certain geometric purposes. A simple analogue of this deformation is defined for CMC1 surfaces which makes the Goursat transform equivariant with respect to the Lawson correspondence, thereby increasing the number of explicitly computable examples of minimal/CMC1 cousin pairs. We then indicate how the Goursat transformation law and integrability conditions for the spin curve of a horospherical surface are analogous to the Lorentz transformation law and equations of motion for the wavefunction of a massless fermion
Resonance region neutronics of unit cells in fast and thermal reactors
Originally presented as the first author's thesis, (Ph. D.)--in the M.I.T. Dept. of Nuclear Engineering, 1977Includes bibliographical references (p. 226-229)ERDA research and development E(11-1)--2250 UC-79P LMFBR-Physic
Cluster-state quantum computation
This article is a short introduction to and review of the cluster-state model
of quantum computation, in which coherent quantum information processing is
accomplished via a sequence of single-qubit measurements applied to a fixed
quantum state known as a cluster state. We also discuss a few novel properties
of the model, including a proof that the cluster state cannot occur as the
exact ground state of any naturally occurring physical system, and a proof that
measurements on any quantum state which is linearly prepared in one dimension
can be efficiently simulated on a classical computer, and thus are not
candidates for use as a substrate for quantum computation.Comment: 15 pages, resubmitted version accepted to Rev. Math. Phy
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