Stable cosmic vortons.

We present solutions in the gauged U(1)×U(1) model of Witten describing vortons-spinning flux loops stabilized against contraction by the centrifugal force. Vortons were heuristically described many years ago; however, the corresponding field theory solutions were not obtained and so the stability issue remained open. We construct explicitly a family of stationary vortons characterized by their charge and angular momentum. Most of them are unstable and break in pieces when perturbed. However, thick vortons with a small radius preserve their form in the 3+1 nonlinear dynamical evolution. This gives the first ever evidence of stable vortons and impacts several branches of physics where they could potentially exist. These range from cosmology, since vortons could perhaps contribute to dark matter, to QCD and condensed matter physics.

Biological characterization of Russian Mycoplasma gallisepticum field isolates.

An earlier study on commercial chickens and turkeys with a history of respiratory disease established Mycoplasma gallisepticum infection rates on 164 poultry farms of the Russian Federation. Forty-seven (29%) of these poultry farms were M. gallisepticum-positive by polymerase chain reaction but isolation of the mycoplasma was successful only on 10 farms. Five field isolates from different farms were selected for pathogenicity studies in specific pathogen-free chicks. Clinical signs, seroconversion, culture rates, air sac and tracheal lesions and mean tracheal mucosal thickness were all assessed in comparison with the reference strain, S6. Of the five isolates, MG140905 and MG070607 appeared to be slightly more pathogenic than the other three, as indicated by clinical signs, culture-positive rates and lesions, but only isolate MG140905 differed statistically (P < 0.05) from them, thus proving to be the most pathogenic. However, none of the Russian field isolates was as pathogenic as the S6 strain by the parameters measured. Stress or other factors such as concurrent bacterial or viral infections may have served as exacerbating factors for the disease seen in the naturally affected flocks. Sequence analysis of the gapA and mgc2 genes showed that MG140905 clustered with M. gallisepticum R(low) and was more distant from the majority of the Russian isolates.

Superconducting vortices in semilocal models.

It is shown that the SU(2) semilocal model--the Abelian Higgs model with two complex scalars--admits a new class of stationary, straight string solutions carrying a persistent current and having finite energy per unit length. In the plane orthogonal to their direction they correspond to a nontrivial deformation of the embedded Abrikosov-Nielsen-Olesen (ANO) vortices by the current flowing through them. The new solutions bifurcate with the ANO vortices in the limit of vanishing current. They can be either static or stationary. In the stationary case, the relative phase of the two scalars rotates at constant velocity, giving rise to an electric field and angular momentum, while the energy remains finite. The new static vortex solutions have lower energy than the ANO vortices and could be of considerable importance in various physical systems (from condensed matter to cosmic strings).

Resonant excitations of the 't Hooft-Polyakov monopole.

The spherically symmetric magnetic monopole in an SU(2) gauge theory coupled to a massless Higgs field is shown to possess an infinite number of resonances or quasinormal modes. These modes are eigenfunctions of the isospin 1 perturbation equations with complex eigenvalues, E(n)=omega(n)-igamma(n), satisfying the outgoing radiation condition. For n--> infinity, their frequencies omega(n) approach the mass of the vector boson, M(W), while their lifetimes 1/gamma(n) tend to infinity. The response of the monopole to an arbitrary initial perturbation is largely determined by these resonant modes, whose collective effect leads to the formation of a long living breatherlike excitation with an amplitude decaying at late times as t(-5/6).