Fermi spectra and their gauge invariance in hot and dense Abelian and non-Abelian theories

The one-loop Fermi spectra (one-particle and collective ones) are found for all momenta in the $T^2$-approximation and their gauge invariance in hot and dense Abelian and non-Abelian theories is studied. It is shown that the one-particle spectrum, if the calculation accuracy is kept strictly, is gauge invariant for all momenta and has two branches as the bare one. The collective spectrum always has four branches which are gauge dependent including also their |\q|=0 limit. The exception is the case $m,\mu=0$ for which this spectrum is gauge invariant for all momenta as well.Comment: 16 pages, latex, no figure

Investigation of the Kerr-lens Mode Locking Ability of Cr:ZnSe Solid-State Laser

The theoretical calculation for nonlinear refractive index in Cr: ZnSe - active medium predicts the strong defocusing cascaded second-order nonlinearity within 2000 - 3000 nm spectral range. On the basis of this result the optimal cavity configuration for Kerr-lens mode locking is proposed that allows to achieve a sub-100 fs pulse duration. The numerical simulations testify about strong destabilizing processes in the laser resulting from a strong self-phase modulation. The stabilization of the ultrashort pulse generation is possible due to spectral filtering that increases the pulse duration up to 300 fs.Comment: 14 pages, 8 Postscript figures, LaTeX, commented Maple program is presented on http://www.geocities.com/optomaple

Soliton absorption spectroscopy

We analyze optical soliton propagation in the presence of weak absorption lines with much narrower linewidths as compared to the soliton spectrum width using the novel perturbation analysis technique based on an integral representation in the spectral domain. The stable soliton acquires spectral modulation that follows the associated index of refraction of the absorber. The model can be applied to ordinary soliton propagation and to an absorber inside a passively modelocked laser. In the latter case, a comparison with water vapor absorption in a femtosecond Cr:ZnSe laser yields a very good agreement with experiment. Compared to the conventional absorption measurement in a cell of the same length, the signal is increased by an order of magnitude. The obtained analytical expressions allow further improving of the sensitivity and spectroscopic accuracy making the soliton absorption spectroscopy a promising novel measurement technique.Comment: 9 pages, 7 figures

Soliton Generation and Picosecond Collapse in Solid-State Lasers with Semiconductor Saturable Absorber

Based on self - consistent field theory we study a soliton generation in cw solid-state lasers with semiconductor saturable absorber. Various soliton destabilizations, i.e. the switch from femtosecond to picosecond generation (''picosecond collapse''), an automodulation regime, breakdown of soliton generation and hysteresis behavior, are predicted.Comment: 14 pages, 6 Postscript figures, Te

Factors and conditions of functioning and development of modern regional socio-economic systems

Purpose: The purpose of this article is the systemic modernization of scientific ideas relating to the essential factors and conditions of functioning and development of regional socioeconomic systems. Design/Methodology/Approach: To substantiate the article about the possibility of overcoming the socio-economic stagnation and recession of the region's economy based on modernization of research tools and management of local and regional socio-economic processes using modern agglomerative technologies and methods. Findings: Finding lies in clarifying the arrangement, structure and importance of socioeconomic processes, factors and conditions of local, regional and interregional level that determine the effectiveness and sustainability of functioning of the economy. Practical Implications: Are determined by the possibility to use authors' scientific results for audit, evaluation and adjustment of regional socio-economic impacts, measures and development programs, used during designing, forecast and assessment of socio-economic and complex efficiency of local and regional socio-economic activeness in the cities and municipal areas. Originality / Value: It is substantiated by development of the theory and methodology of regional studies of socio-economic factors and conditions that determine long-term prospects of stable functioning and sustainable development of the regional economy on the basis of adaptation of the basic direction of the system and reproduction processes.peer-reviewe