4,623 research outputs found
Contractions: Nijenhuis and Saletan tensors for general algebraic structures
Generalizations in many directions of the contraction procedure for Lie
algebras introduced by E.J.Saletan are proposed. Products of arbitrary nature,
not necessarily Lie brackets, are considered on sections of finite-dimensional
vector bundles. Saletan contractions of such infinite-dimensional algebras are
obtained via a generalization of the Nijenhuis tensor approach. In particular,
this procedure is applied to Lie algebras, Lie algebroids, and Poisson
structures. There are also results on contractions of n-ary products and
coproducts.Comment: 25 pages, LateX, corrected typo
Completely integrable systems: a generalization
We present a slight generalization of the notion of completely integrable
systems to get them being integrable by quadratures. We use this generalization
to integrate dynamical systems on double Lie groups.Comment: Latex, 15 page
Construction of completely integrable systems by Poisson mappings
Pulling back sets of functions in involution by Poisson mappings and adding
Casimir functions during the process allows to construct completely integrable
systems. Some examples are investigated in detail.Comment: AmsTeX, 9 page
Generalized n-Poisson brackets on a symplectic manifold
On a symplectic manifold a family of generalized Poisson brackets associated
with powers of the symplectic form is studied. The extreme cases are related to
the Hamiltonian and Liouville dynamics. It is shown that the Dirac brackets can
be obtained in a similar way.Comment: Latex, 10 pages, to appear in Mod. Phys. Lett.
A variational principle for volume-preserving dynamics
We provide a variational description of any Liouville (i.e. volume
preserving) autonomous vector fields on a smooth manifold. This is obtained via
a ``maximal degree'' variational principle; critical sections for this are
integral manifolds for the Liouville vector field. We work in coordinates and
provide explicit formulae
The Influence of Medicare Home Health Payment Incentives: Does Payer Source Matter?
During the late 1990s, an interim payment system (IPS) was instituted to constrain Medicare home health care expenditures. Previous research has largely focused on the implications of the IPS for Medicare patients, but our study broadens the analysis to consider patients with other payer sources. Using the National Home and Hospice Care Survey, we found similar effects of the IPS across payer types. Specifically, the IPS was associated with a decrease in access to care for the sickest patients, less agency assistance with activities of daily living, and shorter length-of-use. However, these changes did not translate into worse discharge outcomes.Medicare, health, incentives
Examining the efficacy of a genotyping-by-sequencing technique for population genetic analysis of the mushroom Laccaria bicolor and evaluating whether a reference genome is necessary to assess homology
Given the diversity and ecological importance of Fungi, there is a lack of population genetic research on these organisms. The reason for this can be explained in part by their cryptic nature and difficulty in identifying genets. In addition the difficulty (relative to plants and animals) in developing molecular markers for fungal population genetics contributes to the lack of research in this area. This study examines the ability of restriction-site associated DNA (RAD) sequencing to generate SNPs in Laccaria bicolor. Eighteen samples of morphologically identified L. bicolor from the United States and Europe were selected for this project. The RAD sequencing method produced anywhere from 290 000 to more than 3 000 000 reads. Mapping these reads to the genome of L. bicolor resulted in 84 000-940 000 unique reads from individual samples. Results indicate that incorporation of non-L. bicolor taxa into the analysis resulted in a precipitous drop in shared loci among samples, suggests the potential of these methods to identify cryptic species. F-statistics were easily calculated, although an observable "noise" was detected when using the "All Loci" treatment versus filtering loci to those present in at least 50% of the individuals. The data were analyzed with tests of Hardy-Weinburg equilibrium, population genetic statistics (FIS and FST), and population structure analysis using the program Structure. The results provide encouraging feedback regarding the potential utility of these methods and their data for population genetic analysis. We were unable to draw conclusions of life history of L. bicolor populations from this dataset, given the small sample size. The results of this study indicate the potential of these methods to address population genetics and general life history questions in the Agaricales. Further research is necessary to explore the specific application of these methods in the Agaricales or other fungal groups
Substitution Laws and Innovation in the Pharmaceutical Industry
When the sensors readings are perturbed by an unknown stochastic time jitter, classical system identification algorithms based on additive amplitude perturbations will give biased estimates. We here outline the maximum likelihood procedure, for the case of both time and amplitude noise, in the frequency domain, based on the measurement DFT. The method directly applies to output error continuous time models, while a simple sinusoid in noise example is used to illustrate the bias removal of the proposed method
Reduction of Lie-Jordan Banach algebras and quantum states
A theory of reduction of Lie-Jordan Banach algebras with respect to either a
Jordan ideal or a Lie-Jordan subalgebra is presented. This theory is compared
with the standard reduction of C*-algebras of observables of a quantum system
in the presence of quantum constraints. It is shown that the later corresponds
to the particular instance of the reduction of Lie-Jordan Banach algebras with
respect to a Lie-Jordan subalgebra as described in this paper. The space of
states of the reduced Lie-Jordan Banach algebras is described in terms of
equivalence classes of extensions to the full algebra and their GNS
representations are characterized in the same way. A few simple examples are
discussed that illustrates some of the main results
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