Regulatory SPS instruments in meat trade

Policy makers have to choose between different potentially risk-reducing instruments regulating agri-food trade. Analysing the meat sector, the paper aims at identifying least trade distorting regulations for different policy goals relevant to the SPS agreement. For this purpose, a non-linear gravity model is estimated by Poisson pseudo-maximum likelihood and applied to a panel data set at HS 4-digit level. Regulations are distinguished by a frequency approach allowing to identify the least trade distorting regulation for each policy objective. The results suggest significant differences of trade impacts between types of sanitary regulations.agri-food trade, gravity model, Poisson regression, Agricultural and Food Policy, Food Consumption/Nutrition/Food Safety, International Relations/Trade, C23, F14, Q17,

Sequential and co-tunneling behavior in the temperature-dependent thermopower of few-electron quantum dots

We have studied the temperature dependent thermopower of gate-defined, lateral quantum dots in the Coulomb blockade regime using an electron heating technique. The line shape of the thermopower oscillations depends strongly on the contributing tunneling processes. Between 1.5 K and 40 mK a crossover from a pure sawtooth- to an intermitted sawtooth-like line shape is observed. The latter is attributed to the increasing dominance of cotunneling processes in the Coulomb blockade regime at low temperatures.Comment: 4 pages, 4 figures, submitted to Phys. Rev.

100 [Hundert] Jahre Echolot : die Tiefe hören ; 4000 Jahre Tiefenmessung im Ozean

Ausstellung „Die Tiefe hören“: Sie beschäftigt sich mit der Entwicklung des Echolots, für das der Kieler Physiker und Unternehmer Alexander Behm vor genau 100 Jahren das erste Patent erhielt. Echolote sind bis heute nicht nur wichtige Hilfsmittel der Schifffahrt, sondern auch unverzichtbare Werkzeuge bei der Erkundung der Ozeanböden. Die Ausstellung zeigt die Entwicklung der Tiefenmessung im Ozean von den Handloten im alten Ägypten bis zur Vermessung der Wasseroberfläche mit Satelliten sowie mit Autonomen Tiefseegeräten, die mit modernen Fächerecholoten ausgestattet sind

Probing the band structure of InAs/GaAs quantum dots by capacitance-voltage and photoluminescence spectroscopy

The band structure of self-assembled InAs quantum dots, embedded in a GaAs matrix, is probed with capacitance-voltage spectroscopy and photoluminescence(PL)spectroscopy. The electron energy levels in the quantum dots with respect to the electron ground state of the wetting layer (WL) are determined from the capacitance-voltage measurements with a linear lever arm approximation. In the region where the linear lever arm approximation is not valid anymore (after the charging of the WL), the energetic distance from the electron ground state of the WL to the GaAs conduction band edge can be indirectly inferred from a numerical simulation of the conduction band under different gate voltages. In combination with PL measurements, the complete energy band diagram of the quantum dot sample is extracted

Spin photocurrents and circular photon drag effect in (110)-grown quantum well structures

We report on the study of spin photocurrents in (110)-grown quantum well structures. Investigated effects comprise the circular photogalvanic effect and so far not observed circular photon drag effect. The experimental data can be described by an analytical expression derived from a phenomenological theory. A microscopic model of the circular photon drag effect is developed demonstrating that the generated current has spin dependent origin.Comment: 6 pages, 3 figure

Observation of two relaxation mechanisms in transport between spin split edge states at high imbalance

Using a quasi-Corbino geometry to directly study electron transport between spin-split edge states, we find a pronounced hysteresis in the I-V curves, originating from slow relaxation processes. We attribute this long-time relaxation to the formation of a dynamic nuclear polarization near the sample edge. The determined characteristic relaxation times are 25 s and 200 s which points to the presence of two different relaxation mechanisms. The two time constants are ascribed to the formation of a local nuclear polarization due to flip-flop processes and the diffusion of nuclear spins.Comment: Submitted to PR