Generalizing Planck's Law: Nonequilibrium Emission of Excited Media

Using a quantum-kinetic many-body approach, exact results for the interacting system of field and matter in a specified geometry are presented. It is shown that both the spectral function of photons and the field fluctuations split up into vacuum- and medium-induced contributions, for which explicit expressions are derived. Using Poynting's theorem, the incoherent emission is analyzed and related to the coherent absorption as may be measured in a linear transmission-reflection experiment. Their ratio defines the medium-induced population of the modes of the transverse electromagnetic field and so generalizes Planck's law to an arbitrarily absorbing and dispersing medium in a nonequilibrium steady state. For quasi-equilibrium, this population develops into a Bose distribution whose chemical potential marks the crossover from absorption to gain and, also, characterizes the degree of excitation. Macroscopic quantum phenomena such as lasing and quantum condensation are discussed on this footing.Comment: minor corrections and extended discussion, as publishe

Absorption and emission of polariton modes in a ZnSe-ZnSSe heterostructure

We investigate the absorption and emission of a 25 nm ZnSe layer, which was grown on a GaAs buffer and cladded by ZnSSe layers. Due to the coupling of light with the exciton resonances, polariton modes propagate through the ZnSe layer. Their interferences appear as additional peaks in the reflection spectra and can be explained by the effect of spatial dispersion. We present additional experimental results for the emission of the sample after excitation by a pump pulse, showing corresponding interference peaks of the polariton modes, whose maxima strongly decrease to higher energies. Our exact theoretical analysis shows that the ratio of emission and absorption is given by the population of the globally defined states of the electromagnetic field, i.e. the polariton distribution which is generated by the pump pulse. This distribution, being far from thermal quasiequilibrium, shows pronounced peaks at the polariton modes depending on the energy of the pump pulse.Comment: 5 pages, 2 figures, RevTex4, changes: as publishe

Optimized Cell Planning for Network Slicing in Heterogeneous Wireless Communication Networks

We propose a cell planning scheme to maximize the resource efficiency of a wireless communication network while considering quality-of-service requirements imposed by different mobile services. In dense and heterogeneous cellular 5G networks, the available time-frequency resources are orthogonally partitioned among different slices, which are serviced by the cells. The proposed scheme achieves a joint optimization of the resource distribution between network slices, the allocation of cells to operate on different slices, and the allocation of users to cells. Since the original problem formulation is computationally intractable, we propose a convex inner approximation. Simulations show that the proposed approach optimizes the resource efficiency and enables a service-centric network design paradigm.Comment: This article has been accepted for publication in a future issue of the IEEE Communications Letters, https://ieeexplore.ieee.org/document/8368293, (c) 2018 IEE

Timidity, emotionality, and activity in rats deprived of grooming

The purpose of this current study was to investigate the effect of restriction of grooming, by means of collars, on activity, emotionality, and timidity. On the basis of the common occurrence of grooming when under stress some relationship between licking and emotionality was assumed to exist by the author. it was therefore expected that differences would be found among the treatment group. The current study made use of a three factor design. One factor was the treatment factor, another factor was the replications factor, and the third was the days factor. The days factor has repeated measures and the replications factor was random