320,337 research outputs found
Building an Open Social Learning Community Around a DSpace Repository on Statistics
4th International Conference on Open RepositoriesThis presentation was part of the session : Conference PostersIn this paper we describe a project which aims to build an open social learning community around a learning object repository (LOR) based on DSpace containing learning resources about Statistics. We combine the preservation capabilities of DSpace with the facilities of a tagging mechanism such as Delicious. On top of this ensemble we intend to build a new browsing interface for improving users' learning experience when using the LOR. We also intend to gather and analyze usage data in order to better understand the real learning process in virtual learning environments.Spanish Government Grant under Refs. TIN2006-15107-C06 and EA2008-015
Controllability Issues of Linear Ensemble Systems
We address an open problem in ensemble control: Whether there exist
controllable linear ensemble systems over high dimensional parameterization
spaces? We provide a negative answer: Any real-analytic linear ensemble system
is not -controllable, for , if the dimension
of its parameterization space is greater than one
Spectral Decorrelation of Nuclear Levels in the Presence of Continuum Decay
The fluctuation properties of nuclear giant resonance spectra are studied in
the presence of continuum decay. The subspace of quasi-bound states is
specified by one-particle one-hole and two-particle two-hole excitations and
the continuum coupling is generated by a scattering ensemble. It is found that,
with increasing number of open channels, the real parts of the complex
eigenvalues quickly decorrelate. This appears to be related to the transition
from power-law to exponential time behavior of the survival probability of an
initially non-stationary state.Comment: 10 Pages, REVTEX, 4 PostScript figure
Jacobians and rank 1 perturbations relating to unitary Hessenberg matrices
In a recent work Killip and Nenciu gave random recurrences for the
characteristic polynomials of certain unitary and real orthogonal upper
Hessenberg matrices. The corresponding eigenvalue p.d.f.'s are
beta-generalizations of the classical groups. Left open was the direct
calculation of certain Jacobians. We provide the sought direct calculation.
Furthermore, we show how a multiplicative rank 1 perturbation of the unitary
Hessenberg matrices provides a joint eigenvalue p.d.f generalizing the circular
beta-ensemble, and we show how this joint density is related to known
inter-relations between circular ensembles. Projecting the joint density onto
the real line leads to the derivation of a random three-term recurrence for
polynomials with zeros distributed according to the circular Jacobi
beta-ensemble.Comment: 23 page
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