2,574 research outputs found
The influence of differential rotation on the detectability of gravitational waves from the r-mode instability
Recently, it was shown that differential rotation is an unavoidable feature
of nonlinear r-modes. We investigate the influence of this differential
rotation on the detectability of gravitational waves emitted by a newly born,
hot, rapidly-rotating neutron star, as it spins down due to the r-mode
instability. We conclude that gravitational radiation may be detected by the
advanced laser interferometer detector LIGO if the amount of differential
rotation at the time the r-mode instability becomes active is not very high.Comment: 8 pages, 6 figures, revtex
CP^n, or, entanglement illustrated
We show that many topological and geometrical properties of complex
projective space can be understood just by looking at a suitably constructed
picture. The idea is to view CP^n as a set of flat tori parametrized by the
positive octant of a round sphere. We pay particular attention to submanifolds
of constant entanglement in CP^3 and give a few new results concerning them.Comment: 28 pages, 9 figure
Phase transition in a mean-field model for sympatric speciation
We introduce an analytical model for population dynamics with intra-specific
competition, mutation and assortative mating as basic ingredients. The set of
equations that describes the time evolution of population size in a mean-field
approximation may be decoupled. We find a phase transition leading to sympatric
speciation as a parameter that quantifies competition strength is varied. This
transition, previously found in a computational model, occurs to be of first
order.Comment: accepted for Physica
The role of biophysical information for the management of fallow systems.
Editado por Reinhard Lieberei, Helmut Bianchi, Vera Boehm, Christoph Reisdorff. Publicado também em GERMAN-BRAZILIAN WORKSHOP ON NEOTROPICAL ECOSYSTEMS: ARCHIEMENTS AND PROPECTS OF COOPERATIVE RESEARCH, 2000, Hamburg. Program and abstracts. Hamburg: SHIFT: MADAM: WAVES, 2000. p. 104
Modification of traditional fallow system towards ecologically sound options.
Editado por Reinhard Lieberei, Helmut Bianchi, Vera Boehm, Christoph Reisdorff. Publicado também em GERMAN-BRAZILIAN WORKSHOP ON NEOTROPICAL ECOSYSTEMS: ARCHIEMENTS AND PROPECTS OF COOPERATIVE RESEARCH, 2000, Hamburg. Program and abstracts. Hamburg: SHIFT: MADAM: WAVES, 2000. p. 65
A constructive algorithm for the Cartan decomposition of SU(2^N)
We present an explicit numerical method to obtain the Cartan-Khaneja-Glaser
decomposition of a general element G of SU(2^N) in terms of its `Cartan' and
`non-Cartan' components. This effectively factors G in terms of group elements
that belong in SU(2^n) with n<N, a procedure that can be iterated down to n=2.
We show that every step reduces to solving the zeros of a matrix polynomial,
obtained by truncation of the Baker-Campbell-Hausdorff formula, numerically.
All computational tasks involved are straightforward and the overall truncation
errors are well under control.Comment: 15 pages, no figures, matlab file at
http://cam.qubit.org/users/jiannis
Ultracold heteronuclear molecules and ferroelectric superfluids
We analyze the possibility of a ferroelectric transition in heteronuclear
molecules consisting of Bose-Bose, Bose-Fermi or Fermi-Fermi atom pairs. This
transition is characterized by the appearance of a spontaneous electric
polarization below a critical temperature. We discuss the existence of a
ferroelectric Fermi liquid phase for Fermi molecules and the existence of a
ferroelectric superfluid phase for Bose molecules characterized by the
coexistence of ferroelectric and superfluid orders. Lastly, we propose an
experiment to detect ferroelectric correlations through the observation of
coherent dipole radiation pulses during time of flight.Comment: 4 pages and 3 figure
Complex networks generated by the Penna bit-string model: emergence of small-world and assortative mixing
The Penna bit-string model successfully encompasses many phenomena of population evolution, including inheritance, mutation, evolution, and aging. If we consider social interactions among individuals in the Penna model, the population will form a complex network. In this paper, we first modify the Verhulst factor to control only the birth rate, and introduce activity-based preferential reproduction of offspring in the Penna model. The social interactions among individuals are generated by both inheritance and activity-based preferential increase. Then we study the properties of the complex network generated by the modified Penna model. We find that the resulting complex network has a small-world effect and the assortative mixing property
Instability of three dimensional conformally dressed black hole
The three dimensional black hole solution of Einstein equations with negative
cosmological constant coupled to a conformal scalar field is proved to be
unstable against linear circularly symmetric perturbations.Comment: 5 pages, REVTe
F-wave versus P-wave Superconductivity in Organic Conductors
Current experimental results suggest that some organic quasi-one-dimensional
superconductors exhibit triplet pairing symmetry. Thus, we discuss several
potential triplet order parameters for the superconducting state of these
systems within the functional integral formulation. We compare weak spin-orbit
coupling , , and symmetries via several thermodynamic
quantities. For each symmetry, we analyse the temperature dependences of the
order parameter, condensation energy, specific heat, and superfluid density
tensor.Comment: 5 pages, 4 figure
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