Cosmological tachyon condensation

We consider the prospects for dark matter/energy unification in k-essence type theories. General mappings are established between the k-essence scalar field, the hydrodynamic and braneworld descriptions. We develop an extension of the general relativistic dust model that incorporates the effects of both pressure and the associated acoustic horizon. Applying this to a tachyon model, we show that this inhomogeneous "variable Chaplygin gas" does evolve into a mixed system containing cold dark matter like gravitational condensate in significant quantities. Our methods can be applied to any dark energy model as well as to mixtures of dark energy and traditional dark matter.Comment: 22 pages, 3 figures, title changed, typos corrected, accepted in Phys. Rev.

Between fragmenting and multiplying: scale-shift processes in Serbian and Croatian antiwar activisms

This paper follows the almost contemporaneous emergence of the two primary antiwar initiatives in Belgrade and Zagreb to explore how they acted as hotbeds from which permanent human rights organizations appeared in the newly created nation-states. Drawing mostly upon in-depth interviews with antiwar activists from Serbia and Croatia, I argue that the dominant patterns of protest expansion were different in the two countries. While cooperation and tensions existed within both antiwar groups, the Antiwar Campaign of Croatia acted as a broker, leading toward the multiplication of civic initiatives; on the other hand, the Belgrade Center for Antiwar Action was characterized by ideological, professional, and personal divisions, which caused a rapid fragmentation of antiwar undertakings. This paper outlines the main reasons for such expansion patterns (scale-shift processes) and discusses them in the light of recent theoretical advances in political contention studies

Chaplygin Gas Cosmology - Unification of Dark Matter and Dark Energy

The models that unify dark matter and dark energy based upon the Chaplygin gas fail owing to the suppression of structure formation by the adiabatic speed of sound. Including string theory effects, in particular the Kalb-Ramond field, we show how nonadiabatic perturbations allow a successful structure formation.Comment: 7 pages, presented by N. B. at IRGAC 2006, Barcelona, 11-15 July 2006, typos corrected, concluding paragraph slightly expanded, final version, accepted in J. Phys. A, special issu

Enhancement of preasymptotic effects in inclusive beauty decays

We extend Voloshin's recent analysis of charmed and beauty hyperon decays based on SU(3) symmetry and heavy quark effective theory, by introducing a rather moderate model-dependence, in order to obtain more predictive power, e.g. the values of lifetimes of the (\Lambda_{b},\Xi_{b}) hyperon triplet and the lifetime of \Omega_{b}. In this way we obtain an improvement of the ratio \tau(\Lambda_{b})/\tau(B_{d}^{0}) \sim 0.9 and the hierarchy of lifetimes \tau(\Lambda_{b}) \simeq \tau(\Xi_{b}^{0}) < \tau(\Xi_{b}^{-}) < \tau(\Omega_{b}) with lifetimes of \Xi_{b}^{-} and \Omega_{b} exceeding the lifetime of \Lambda_{b} by 22% and 35%, respectively.Comment: Latex2e, 12 pages, 3 eps figures include

On the Formation of Degenerate Heavy Neutrino Stars

The dynamics of a self-gravitating cold Fermi gas is described using the analogy with an interacting self-gravitating Bose condensate having the same Thomas-Fermi limit. The dissipationless formation of a heavy neutrino star through gravitational collapse and ejection of matter is demonstrated numerically. Such neutrino stars offer an alternative to black holes for the supermassive compact dark objects at the centers of galaxies.Comment: 11 pages, 3 figures, Latex, elsart.sty, fig1 improved, to appear in Phys. Lett.

General-Relativistic Thomas-Fermi model

A system of self-gravitating massive fermions is studied in the framework of the general-relativistic Thomas-Fermi model. We study the properties of the free energy functional and its relation to Einstein's field equations. A self-gravitating fermion gas we then describe by a set of Thomas-Fermi type self-consistency equations.Comment: 7 pages, LaTex, to appear in Gen. Rel. Gra

On the Segregation Phenomenon in Complex Langevin Simulation

In the numerical simulation of certain field theoretical models, the complex Langevin simulation has been believed to fail due to the violation of ergodicity. We give a detailed analysis of this problem based on a toy model with one degree of freedom ($S=-\beta\cos\theta$). We find that the failure is not due to the defect of complex Langevin simulation itself, but rather to the way how one treats the singularity appearing in the drift force. An effective algorithm is proposed by which one can simulate the ${1/\beta}$ behaviour of the expectation value $$ in the small $\beta$ limit.Comment: (20 pages + 8 figures on request). Siegen Si-93-8, Tokuyama TKYM-93-

Gauging the Shadow Sector with SO(3)

We examine the phenomenology of a low-energy extension of the Standard Model, based on the gauge group SU(3) x SU(2) x U(1) x SO(3), with SO(3) operating in the shadow sector. This model offers $\nu_{e} \to \nu_{s}$ and $\nu_{\mu} \to \nu_{\tau}$ oscillations as the solution of the solar and atmospheric neutrino problems. Moreover, it provides a neutral heavy shadow lepton X that could play the role of a cold dark matter particle.Comment: 8 page

Focal laryngeal dystonia: diagnostics, therapeutics and novelties in neurophysiologic research

Aim of study: To present and discuss diagnostic procedures, therapeutic options and novelties in neurophysiological research of laryngeal dystonia (LD), a rare movement disorder with an unknown cause affecting the intrinsic muscles of the larynx. Material and methods: 1) Literature overview of the on the standard guidelines in the diagnostics and treatment of LD; 2) The use of transcranial magnetic stimulation (TMS) in the neurophysiologic research of LD by investigation of cortical silent period (cSP) reflecting the intracortical inhibitory process mediated by GABAA and GABAB receptors; 3) The use of navigated TMS in mapping the laryngeal motor cortex by investigating the duration of cortical silent period in two LD cases, abductor and adductor LD type. Results: The study presents standard diagnostic, treatment of LD disorder, and results of investigation by groups from School of Medicine, University of Minnesota, Minneapolis, MN, USA and School of Medicine, University of Split, Croatia on the duration of cSP in vocal and cricothyroid muscles in LD patients and healthy control subjects. The research groups presented norms for cSP duration in vocal and cricothyroid muscle in healthy subjects and pointed to the altered (shortened) duration of the cSP in LD patients (adductor type). Conclusion: The cSP measure might be useful neurophysiologic biomarker for understanding the LD disorder. In LD, the cortical activation during phonation may not be efficiently or effectively associated with inhibitory processes, leading to muscular dysfunction. Promising techniques such as TMS might bring new light to the diagnosis and treatment of LD disorder

Focal laryngeal dystonia: diagnostics, therapeutics and novelties in neurophysiologic research

Aim of study: To present and discuss diagnostic procedures, therapeutic options and novelties in neurophysiological research of laryngeal dystonia (LD), a rare movement disorder with an unknown cause affecting the intrinsic muscles of the larynx. Material and methods: 1) Literature overview of the on the standard guidelines in the diagnostics and treatment of LD; 2) The use of transcranial magnetic stimulation (TMS) in the neurophysiologic research of LD by investigation of cortical silent period (cSP) reflecting the intracortical inhibitory process mediated by GABAA and GABAB receptors; 3) The use of navigated TMS in mapping the laryngeal motor cortex by investigating the duration of cortical silent period in two LD cases, abductor and adductor LD type. Results: The study presents standard diagnostic, treatment of LD disorder, and results of investigation by groups from School of Medicine, University of Minnesota, Minneapolis, MN, USA and School of Medicine, University of Split, Croatia on the duration of cSP in vocal and cricothyroid muscles in LD patients and healthy control subjects. The research groups presented norms for cSP duration in vocal and cricothyroid muscle in healthy subjects and pointed to the altered (shortened) duration of the cSP in LD patients (adductor type). Conclusion: The cSP measure might be useful neurophysiologic biomarker for understanding the LD disorder. In LD, the cortical activation during phonation may not be efficiently or effectively associated with inhibitory processes, leading to muscular dysfunction. Promising techniques such as TMS might bring new light to the diagnosis and treatment of LD disorder