Keldysh field theory for nonequilibrium condensation in a parametrically pumped polariton system

We develop a quantum field theory for parametrically pumped polaritons using Keldysh Green's function techniques. By considering the mean-field and Gaussian fluctuations, we find that the low energy physics of the highly non-equilibrium phase transition to the optical parametric oscillator regime is in many ways similar to equilibrium condensation. In particular, we show that this phase transition can be associated with an effective chemical potential, at which the system's bosonic distribution function diverges, and an effective temperature. As in equilibrium systems, the transition is achieved by tuning this effective chemical potential to the energy of the lowest normal mode. Since the occupations of the modes are available, we determine experimentally observable properties, such as the luminescence and absorption spectra.Comment: 16 pages, 14 figure

Keldysh field theory for nonequilibrium condensation in a parametrically pumped polariton system

We develop a quantum field theory for parametrically pumped polaritons using Keldysh Green's function techniques with which the occupations of the excitation spectra can be calculated. By considering the mean field and Gaussian fluctuations, we find that the highly nonequilibrium phase transition to the optical parametric oscillator regime is in some ways similar to equilibrium condensation. In particular, we show that this phase transition can be associated with an effective chemical potential, at which the system's bosonic distribution function diverges, and an effective temperature for low energy modes. As in equilibrium systems, the transition is achieved by tuning this effective chemical potential to the energy of the lowest normal mode. Since the nonequilibrium occupations of the modes are available, we determine experimentally observable properties such as the luminescence and absorption spectra

Rare quantum metastable states in the strongly dispersive Jaynes-Cummings oscillator

We present evidence of metastable rare quantum-fluctuation switching for the driven dissipative Jaynes-Cummings oscillator coupled to a zero-temperature bath in the strongly dispersive regime. We show that single-atom complex amplitude bistability is accompanied by the appearance of a low-amplitude long-lived transient state, hereinafter called `dark state', having a distribution with quasi-Poissonian statistics both for the coupled qubit and cavity mode. We find that the dark state is linked to a spontaneous flipping of the qubit state, detuning the cavity to a low-photon response. The appearance of the dark state is correlated with the participation of the two metastable states in the dispersive bistability, as evidenced by the solution of the Master Equation and single quantum trajectories.Comment: Extensively revised text, 18 revised figures (16 in main and 2 in appendix), 38(+1) references, appendi

Infrastructure's and housing's development in the rural areas in Poland - some problems

The article refers to an analysis and an evaluation of changes in the technical infrastructure and housing in the rural areas in Poland in the years 1995-2008. The article covered all rural and rural-urban (excluding urban parts) gminas in Poland that altogether amount to 2,172 units (as of 2008). It was stated that in the rural areas in Poland a population density increases and it is caused mainly by dynamic suburbanisation processes and by a population movement from cities and towns towards suburban gminas, in the less degree by a natural increase. In the article there were presented spatial variations of rural gminas in the following elements: a length of the water-line and sewerage networks per 100 km2; a share of water-line and of sewerage systems’ users; a number of dwellings per 1,000 population; a number of rooms per 1 person; the usable floor space of a dwelling in m2 per 1 person; a share of dwellings fitted with water-line system and a share of dwellings equipped with flush toilet and bathroom. It was also shown that there are relationships between population density and infrastructure’s and housing’s elements by proving positive as well as negative correlations

How to reduce the number of rating scale items without predictability loss?

Rating scales are used to elicit data about qualitative entities (e.g., research collaboration). This study presents an innovative method for reducing the number of rating scale items without the predictability loss. The "area under the receiver operator curve method" (AUC ROC) is used. The presented method has reduced the number of rating scale items (variables) to 28.57\% (from 21 to 6) making over 70\% of collected data unnecessary. Results have been verified by two methods of analysis: Graded Response Model (GRM) and Confirmatory Factor Analysis (CFA). GRM revealed that the new method differentiates observations of high and middle scores. CFA proved that the reliability of the rating scale has not deteriorated by the scale item reduction. Both statistical analysis evidenced usefulness of the AUC ROC reduction method.Comment: 14 pages, 5 figure

POLISH TOWNS AND THE CHANGES IN THEIR AREAS AND POPULATION DENSITIES

DOI: 10.2478 Available on-line at: http://www.bulletinofgeography.umk.pl http://versita.com/bgssThis article presents the spatial and population density changes in Polish towns in the years 1960–2003. The assumed time frame allowed identifying area changes for a complete set of towns in different socio-economic conditions: the period of intense industrialisation, the economic crisis of the 1980s, the period of economic transition and finally in the years of a market economy. The investigation revealed that the trend shown by changes and the size of a town as measured by the number of its population are distinctly interrelated. It also demonstrated a much stronger dynamics of changes in the first subperiod, i.e. years 1960–1985, followed by a phase of relative stabilization (compared with the previous period) after the year 1980 (mainly of the spatial changes). Moreover, change intensity and change trends observed for the urban areas and population densities vary considerably in terms of space

Simultaneous bistability of qubit and resonator in circuit quantum electrodynamics

We explore the joint activated dynamics exhibited by two quantum degrees of freedom: a cavity mode oscillator which is strongly coupled to a superconducting qubit in the strongly coherently driven dispersive regime. Dynamical simulations and complementary measurements show a range of parameters where both the cavity and the qubit exhibit sudden simultaneous switching between two metastable states. This manifests in ensemble averaged amplitudes of both the cavity and qubit exhibiting a partial coherent cancellation. Transmission measurements of driven microwave cavities coupled to transmon qubits show detailed features which agree with the theory in the regime of simultaneous switching

A comparison of the Antileukaemic Effects of Recombinant Human Tumour Necrosis Factor-α and its Muteins on Leukaemia L1210 and Leukaemia P388 in Mice

We investigated the influence of recombinant human tumour necrosis factor alpha (TNF-α) and its derivatives termed muteins III, V, VI—in which the first 3 to 7 amino acids of native TNF-α have been replaced—on the survival time of mice inoculated with leukaemia L1210 or leukaemia P338. TNF-α prolonged the survival of mice with leukaemia L1210 but did not have any therapeutic activity in leukaemia P388-bearing mice. Muteins-treated mice with leukaemia P388 lived longer than animals receiving TNF-α, while those inoculated with leukaemia L1210 did not show any significant prolongation of life compared with the TNF-α treated group. The results presented in this report indicate that the antileukaemic activity of TNF-α is governed at least in part by the nature of the N-terminal amino acids