Initial Allocation Effects in Permit Markets with Bertrand Output Oligopoly

We analyse the efficiency effects of the initial permit allocation given to firms with market power in both permit and output market. We examine two models: a long- run model with endogenous technology and capacity choice, and a short-run model with fixed technology and capacity. In the long run, quantity pre-commitment with Bertrand competition can yield Cournot outcomes also under emissions trading. In the short run, Bertrand output competition reproduces the effects derived under Cournot competition, but displays higher pass-through profits. In a second-best setting of overallocation, a tighter emissions target tends to improve permit-market efficiency in the short run.Emissions trading, Initial permit allocation, Bertrand competition, EU ETS, Endogenous technology choice, Kreps and Scheinkman, Resource /Energy Economics and Policy, L13, Q28, D43,

Atmosphere above a large solar pore

A large solar pore with a granular light bridge was observed on October 15, 2008 with the IBIS spectrometer at the Dunn Solar Telescope and a 69-min long time series of spectral scans in the lines Ca II 854.2 nm and Fe I 617.3 nm was obtained. The intensity and Doppler signals in the Ca II line were separated. This line samples the middle chromosphere in the core and the middle photosphere in the wings. Although no indication of a penumbra is seen in the photosphere, an extended filamentary structure, both in intensity and Doppler signals, is observed in the Ca II line core. An analysis of morphological and dynamical properties of the structure shows a close similarity to a superpenumbra of a sunspot with developed penumbra. A special attention is paid to the light bridge, which is the brightest feature in the pore seen in the Ca II line centre and shows an enhanced power of chromospheric oscillations at 3-5 mHz. Although the acoustic power flux in the light bridge is five times higher than in the "quiet" chromosphere, it cannot explain the observed brightness.Comment: 6 pages, 3 figures, accepted in Journal of Physics: Conference Serie

Statistics of conductance oscillations of a quantum dot in the Coulomb-blockade regime

The fluctuations and the distribution of the conductance peak spacings of a quantum dot in the Coulomb-blockade regime are studied and compared with the predictions of random matrix theory (RMT). The experimental data were obtained in transport measurements performed on a semiconductor quantum dot fabricated in a GaAs-AlGaAs heterostructure. It is found that the fluctuations in the peak spacings are considerably larger than the mean level spacing in the quantum dot. The distribution of the spacings appears Gaussian both for zero and for non-zero magnetic field and deviates strongly from the RMT-predictions.Comment: 7 pages, 4 figure

Chromospheric heating by acoustic waves compared to radiative cooling

Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of solar atmosphere. A weak chromospheric plage near a large solar pore NOAA 11005 was observed on October 15, 2008 in the lines Fe I 617.3 nm and Ca II 853.2 nm with the Interferometric Bidimemsional Spectrometer (IBIS) attached to the Dunn Solar Telescope. Analyzing the Ca II observations with spatial and temporal resolutions of 0.4" and 52 s, the energy deposited by acoustic waves is compared with that released by radiative losses. The deposited acoustic flux is estimated from power spectra of Doppler oscillations measured in the Ca II line core. The radiative losses are calculated using a grid of seven 1D hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of maps of radiative losses and acoustic flux is 72 %. In quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only of about 15 %. In active areas with photospheric magnetic field strength between 300 G and 1300 G and inclination of 20-60 degrees, the contribution increases from 23 % (chromospheric network) to 54 % (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.Comment: 9 pages, 10 figures. Accepted for publication in The Astrophysical Journa

Dynamics of the solar atmosphere above a pore with a light bridge

Context: Solar pores are small sunspots lacking a penumbra that have a prevailing vertical magnetic field component. They can include light bridges at places with locally reduced magnetic field. Like sunspots, they exhibit a wide range of oscillatory phenomena. Aims: A large isolated pore with a light bridge (NOAA 11005) is studied to obtain characteristics of a chromospheric filamentary structure around the pore, to analyse oscillations and waves in and around the pore, and to understand the structure and brightness of the light bridge. Methods: Spectral imaging observations in the line Ca II 854.2 nm and complementary spectropolarimetry in Fe I lines, obtained with the DST/IBIS spectrometer and HINODE/SOT spectropolarimeter, were used to measure photospheric and chromospheric velocity fields, oscillations, waves, the magnetic field in the photosphere, and acoustic energy flux and radiative losses in the chromosphere. Results: The chromospheric filamentary structure around the pore has all important characteristics of a superpenumbra: it shows an inverse Evershed effect and running waves, and has a similar morphology and oscillation character. The granular structure of the light bridge in the upper photosphere can be explained by radiative heating. Acoustic waves leaking up from the photosphere along the inclined magnetic field in the light bridge transfer enough energy flux to balance the total radiative losses of the light-bridge chromosphere. Conclusions: The presence of a penumbra is not a necessary condition for the formation of a superpenumbra. The light bridge is heated by radiation in the photosphere and by acoustic waves in the chromosphere.Comment: 14 pages, 14 figures, 3 tables, accepted for publication in Astrononomy & Astrophysic

Transport properties of quantum dots with hard walls

Quantum dots are fabricated in a Ga[Al]As-heterostructure by local oxidation with an atomic force microscope. This technique, in combination with top gate voltages, allows us to generate steep walls at the confining edges and small lateral depletion lengths. The confinement is characterized by low-temperature magnetotransport measurements, from which the dots' energy spectrum is reconstructed. We find that in small dots, the addition spectrum can qualitatively be described within a Fock-Darwin model. For a quantitative analysis, however, a hard-wall confinement has to be considered. In large dots, the energy level spectrum deviates even qualitatively from a Fock-Darwin model. The maximum wall steepness achieved is of the order of 0.4 meV/nm.Comment: 9 pages, 5 figure

Transport properties of quantum dots with hard walls

Quantum dots are fabricated in a Ga[Al]As-heterostructure by local oxidation with an atomic force microscope. This technique, in combination with top gate voltages, allows us to generate steep walls at the confining edges and small lateral depletion lengths. The confinement is characterized by low-temperature magnetotransport measurements, from which the dots' energy spectrum is reconstructed. We find that in small dots, the addition spectrum can qualitatively be described within a Fock-Darwin model. For a quantitative analysis, however, a hard-wall confinement has to be considered. In large dots, the energy level spectrum deviates even qualitatively from a Fock-Darwin model. The maximum wall steepness achieved is of the order of 0.4 meV/nm.Comment: 9 pages, 5 figure