569 research outputs found
Self-similar solutions of semilinear wave equations with a focusing nonlinearity
We prove that in three space dimensions a nonlinear wave equation
with being an odd integer has a countable
family of regular spherically symmetric self-similar solutions.Comment: 12 pages, 3 figures, minor corrections to match the published versio
Search for CP-violating nuclear magnetic quadrupole moment using the LuOH cation
The CP-violating interaction of the nuclear magnetic quadrupole moment (MQM)
of the Lu nucleus with electrons in the molecular cation LuOH is
studied. The resulting effect is expressed in terms of CP-odd parameters, such
as quantum chromodynamics angle , quark electric dipole moment
(EDM) and chromo-EDM. For this we have performed a calculation of the nuclear
MQM as well as the molecular constant that characterises the interaction of
this MQM of Lu with electrons. Additionally, we predict the hyperfine
structure constants for the ground electronic state of LuOH. We conclude
that LuOH is a promising system to measure the nuclear MQM
Black Hole Critical Phenomena Without Black Holes
Studying the threshold of black hole formation via numerical evolution has
led to the discovery of fascinating nonlinear phenomena. Power-law mass
scaling, aspects of universality, and self-similarity have now been found for a
large variety of models. However, questions remain. Here I briefly review
critical phenomena, discuss some recent results, and describe a model which
demonstrates similar phenomena without gravity.Comment: 13 pages, 6 figures; Submission for the proceedings of ICGC 2000 in
the journal Preman
Centennial clonal stability of asexual Daphnia in Greenland lakes despite climate variability
Climate and environmental condition drive biodiversity at many levels of biological organization, from populations to ecosystems. Combined with paleoecological reconstructions, palaeogenetic information on resident populations provides novel insights into evolutionary trajectories and genetic diversity driven by environmental variability. While temporal observations of changing genetic structure are often made of sexual populations, little is known about how environmental change affects the long‐term fate of asexual lineages. Here, we provide information on obligately asexual, triploid Daphnia populations from three Arctic lakes in West Greenland through the past 200–300 years to test the impact of environmental change on the temporal and spatial population genetic structure. The contrasting ecological state of the lakes, specifically regarding salinity and habitat structure may explain the observed lake‐specific clonal composition over time. Palaeolimnological reconstructions show considerable regional environmental fluctuations since 1,700 (the end of the Little Ice Age), but the population genetic structure in two lakes was almost unchanged with at most two clones per time period. Their local populations were strongly dominated by a single clone that has persisted for 250–300 years. We discuss possible explanations for the apparent population genetic stability: (a) persistent clones are general‐purpose genotypes that thrive under broad environmental conditions, (b) clonal lineages evolved subtle genotypic differences unresolved by microsatellite markers, or (c) epigenetic modifications allow for clonal adaptation to changing environmental conditions. Our results motivate research into the mechanisms of adaptation in these populations, as well as their evolutionary fate in the light of accelerating climate change in the polar regions
Integrability in Theories with Local U(1) Gauge Symmetry
Using a recently developed method, based on a generalization of the zero
curvature representation of Zakharov and Shabat, we study the integrability
structure in the Abelian Higgs model. It is shown that the model contains
integrable sectors, where integrability is understood as the existence of
infinitely many conserved currents. In particular, a gauge invariant
description of the weak and strong integrable sectors is provided. The
pertinent integrability conditions are given by a U(1) generalization of the
standard strong and weak constraints for models with two dimensional target
space. The Bogomolny sector is discussed, as well, and we find that each
Bogomolny configuration supports infinitely many conserved currents. Finally,
other models with U(1) gauge symmetry are investigated.Comment: corrected typos, version accepted in J. Phys.
Pseudo-relativistic Hartree-Fock and fully relativistic Dirac-Hartree-Fock calculations of radiative parameters in the fifth spectrum of lutetium (Lu V)
peer reviewe
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