12,556 research outputs found
Modulational instability of nonlinear polarization mode coupling in microresonators
We investigate frequency comb generation in the presence of polarization
effects induced by nonlinear mode coupling in microresonator devices. A set of
coupled temporal Lugiato-Lefever equations are derived to model the propagation
dynamics, and an in-depth study is made of the modulational instability of
their multistable homogeneous steady-state solutions. It is shown that new
kinds of instabilities can occur for co-propagating fields that interact
through nonlinear cross-phase modulation. These instabilities display
properties that differ from their scalar counterpart, and are shown to result
in the generation of new types of incoherently coupled frequency comb states.Comment: 8 pages, 7 figure
Spin Measurements in lp -> hX Deep Inelastic Scattering
The production of hadrons in polarized lepton-nucleon deep inelastic
scattering is discussed. The helicity density matrix of the hadron is computed
within the QCD hard scattering formalism and its elements are shown to yield
information on the spin structure of the nucleon and the spin dependence of the
quark fragmentation process. The case of vector mesons is considered in
more detail and estimates are given.Comment: 3 pages, LaTeX, no figures. Talk delivered by J. Hansson at the XII
International Symposium on High Energy Spin Physics, Amsterdam, Sept. 10-14,
1996. To be published in the proceeding
A Scalar Wigner Theory for Polarized Light in Nonlinear Kerr Media
A scalar Wigner distribution function for describing polarized light is
proposed in analogy with the treatment of spin variables in quantum kinetic
theory. The formalism is applied to the propagation of circularly polarized
light in nonlinear Kerr media and an extended phase space evolution equation is
derived along with invariant quantities. We further consider modulation
instability as well as the extension to partially coherent fields.Comment: 6 page
Dynamical two electron states in a Hubbard-Davydov model
We study a model in which a Hubbard Hamiltonian is coupled to the dispersive
phonons in a classical nonlinear lattice. Our calculations are restricted to
the case where we have only two quasi-particles of opposite spins, and we
investigate the dynamics when the second quasi-particle is added to a state
corresponding to a minimal energy single quasi-particle state. Depending on the
parameter values, we find a number of interesting regimes. In many of these,
discrete breathers (DBs) play a prominent role with a localized lattice mode
coupled to the quasiparticles. Simulations with a purely harmonic lattice show
much weaker localization effects. Our results support the possibility that DBs
are important in HTSC.Comment: 14 pages, 12 fig
Functional morphology of the primary olfactory centers in the brain of the hermit crab Coenobita clypeatus (Anomala, Coenobitidae)
Terrestrial hermit crabs of the genus Coenobita display strong behavioral responses to volatile odors and are attracted by chemical cues of various potential food sources. Several aspects of their sense of aerial olfaction have been explored in recent years including behavioral aspects and structure of their peripheral and central olfactory pathway. Here, we use classical histological methods and immunohistochemistry against the neuropeptides orcokinin and allatostatin as well as synaptic proteins and serotonin to provide insights into the functional organization of their primary olfactory centers in the brain, the paired olfactory lobes. Our results show that orcokinin is present in the axons of olfactory sensory neurons, which target the olfactory lobe. Orcokinin is also present in a population of local olfactory interneurons, which may relay lateral inhibition across the array of olfactory glomeruli within the lobes. Extensive lateral connections of the glomeruli were also visualized using the histological silver impregnation method according to Holmes-Blest. This technique also revealed the structural organization of the output pathway of the olfactory system, the olfactory projection neurons, the axons of which target the lateral protocerebrum. Within the lobes, the course of their axons seems to be reorganized in an axon-sorting zone before they exit the system. Together with previous results, we combine our findings into a model on the functional organization of the olfactory system in these animals
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