12,140 research outputs found
Determining Structurally Identifiable Parameter Combinations Using Subset Profiling
Identifiability is a necessary condition for successful parameter estimation
of dynamic system models. A major component of identifiability analysis is
determining the identifiable parameter combinations, the functional forms for
the dependencies between unidentifiable parameters. Identifiable combinations
can help in model reparameterization and also in determining which parameters
may be experimentally measured to recover model identifiability. Several
numerical approaches to determining identifiability of differential equation
models have been developed, however the question of determining identifiable
combinations remains incompletely addressed. In this paper, we present a new
approach which uses parameter subset selection methods based on the Fisher
Information Matrix, together with the profile likelihood, to effectively
estimate identifiable combinations. We demonstrate this approach on several
example models in pharmacokinetics, cellular biology, and physiology
Ground State Spin Structure of Strongly Interacting Disordered 1D Hubbard Model
We study the influence of on-site disorder on the magnetic properties of the
ground state of the infinite U 1D Hubbard model. We find that the ground state
is not ferromagnetic. This is analyzed in terms of the algebraic structure of
the spin dependence of the Hamiltonian. A simple explanation is derived for the
1/N periodicity in the persistent current for this model.Comment: 3 pages, no figure
Projection of two biphoton qutrits onto a maximally entangled state
Bell state measurements, in which two quantum bits are projected onto a
maximally entangled state, are an essential component of quantum information
science. We propose and experimentally demonstrate the projection of two
quantum systems with three states (qutrits) onto a generalized maximally
entangled state. Each qutrit is represented by the polarization of a pair of
indistinguishable photons - a biphoton. The projection is a joint measurement
on both biphotons using standard linear optics elements. This demonstration
enables the realization of quantum information protocols with qutrits, such as
teleportation and entanglement swapping.Comment: 4 pages, 3 figures, published versio
Breaking of N=8 magicity in 13Be
Structure of Be was investigated with antisymmetrized molecular
dynamics. The variation after spin and parity projections was performed. An
unnatural parity state was suggested to be lower than state
indicating that vanishing of the N=8 magic number occurs in Be. A
low-lying state with a configuration was also suggested.
Developed cluster structures were found in the intruder states. Lowering
mechanism of the intruder states was discussed in terms of molecular orbitals
around a core.Comment: 9 pages, 8 figures, submitted to PR
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