81 research outputs found
Functoriality and duality in Morse-Conley-Floer homology
In~\cite{rotvandervorst} a homology theory --Morse-Conley-Floer homology--
for isolated invariant sets of arbitrary flows on finite dimensional manifolds
is developed. In this paper we investigate functoriality and duality of this
homology theory. As a preliminary we investigate functoriality in Morse
homology. Functoriality for Morse homology of closed manifolds is
known~\cite{abbondandoloschwarz, aizenbudzapolski,audindamian,
kronheimermrowka, schwarz}, but the proofs use isomorphisms to other homology
theories. We give direct proofs by analyzing appropriate moduli spaces. The
notions of isolating map and flow map allows the results to generalize to local
Morse homology and Morse-Conley-Floer homology. We prove Poincar\'e type
duality statements for local Morse homology and Morse-Conley-Floer homology.Comment: To appear in the Journal of Fixed Point theory and its Application
Morse-Conley-Floer Homology
For Morse-Smale pairs on a smooth, closed manifold the Morse-Smale-Witten
chain complex can be defined. The associated Morse homology is isomorphic to
the singular homology of the manifold and yields the classical Morse relations
for Morse functions. A similar approach can be used to define homological
invariants for isolated invariant sets of flows on a smooth manifold, which
gives an analogue of the Conley index and the Morse-Conley relations. The
approach will be referred to as Morse-Conley-Floer homology
Morse theory on spaces of braids and Lagrangian dynamics
In the first half of the paper we construct a Morse-type theory on certain
spaces of braid diagrams. We define a topological invariant of closed positive
braids which is correlated with the existence of invariant sets of parabolic
flows defined on discretized braid spaces. Parabolic flows, a type of
one-dimensional lattice dynamics, evolve singular braid diagrams in such a way
as to decrease their topological complexity; algebraic lengths decrease
monotonically. This topological invariant is derived from a Morse-Conley
homotopy index and provides a gloablization of `lap number' techniques used in
scalar parabolic PDEs.
In the second half of the paper we apply this technology to second order
Lagrangians via a discrete formulation of the variational problem. This
culminates in a very general forcing theorem for the existence of infinitely
many braid classes of closed orbits.Comment: Revised version: numerous changes in exposition. Slight modification
of two proofs and one definition; 55 pages, 20 figure
Continuation Sheaves in Dynamics: Sheaf Cohomology and Bifurcation
Continuation of algebraic structures in families of dynamical systems is
described using category theory, sheaves, and lattice algebras. Well-known
concepts in dynamics, such as attractors or invariant sets, are formulated as
functors on appropriate categories of dynamical systems mapping to categories
of lattices, posets, rings or abelian groups. Sheaves are constructed from such
functors, which encode data about the continuation of structure as system
parameters vary. Similarly, morphisms for the sheaves in question arise from
natural transformations. This framework is applied to a variety of lattice
algebras and ring structures associated to dynamical systems, whose algebraic
properties carry over to their respective sheaves. Furthermore, the cohomology
of these sheaves are algebraic invariants which contain information about
bifurcations of the parametrized systems
Undoped and in-situ B doped GeSn epitaxial growth on Ge by atmospheric pressure-chemical vapor deposition
The Drosophila homologue of Rootletin is required for mechanosensory function and ciliary rootlet formation in chordotonal sensory neurons
BACKGROUND: In vertebrates, rootletin is the major structural component of the ciliary rootlet and is also part of the tether linking the centrioles of the centrosome. Various functions have been ascribed to the rootlet, including maintenance of ciliary integrity through anchoring and facilitation of transport to the cilium or at the base of the cilium. In Drosophila, Rootletin function has not been explored. RESULTS: In the Drosophila embryo, Rootletin is expressed exclusively in cell lineages of type I sensory neurons, the only somatic cells bearing a cilium. Expression is strongest in mechanosensory chordotonal neurons. Knock-down of Rootletin results in loss of ciliary rootlet in these neurons and severe disruption of their sensory function. However, the sensory cilium appears largely normal in structure and in localisation of proteins suggesting no strong defect in ciliogenesis. No evidence was found for a defect in cell division. CONCLUSIONS: The role of Rootletin as a component of the ciliary rootlet is conserved in Drosophila. In contrast, lack of a general role in cell division is consistent with lack of centriole tethering during the centrosome cycle in Drosophila. Although our evidence is consistent with an anchoring role for the rootlet, severe loss of mechanosensory function of chordotonal (Ch) neurons upon Rootletin knock-down may suggest a direct role for the rootlet in the mechanotransduction mechanism itself
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