A blessing in disguise?! Discretion in the context of EU decision-making, national transposition and legitimacy regarding EU directives

This dissertation looks into the role of discretion granted by EU directives in EU legislative decision-making and national transposition processes. It applies a qualitative single country-study, focusing on the transposition of six directives in the Netherlands, from the policy areas of consumer protection, environment and justice and home affairs (migration). In the theoretical part the concept of discretion is explored, using insights from both the legal and political sciences. The empirical analysis then presents both EU and national processes regarding the six directives, addressed individually as well as in a comparative manner. This study contributes to clarifying the reasons and circumstances regarding the granting of different margins of discretion to Member States and the effects of discretion on EU negotiations and national transposition. It confirms that discretion can have facilitating and impeding effects on transposition, explains why, and identifies other factors affecting transposition by interacting with discretion. Additionally, a more fine-grained approach to measuring discretion is proposed than hitherto. Finally, but addressed separately from the empirical analysis, the link between discretion and legitimacy is elaborated. It is argued that discretion in national transposition processes can be used to enhance the directives’ input, throughput and output legitimacy within national law

Nonequilibrium stabilization of charge states in double quantum dots

We analyze the decoherence of charge states in double quantum dots due to cotunneling. The system is treated using the Bloch-Redfield generalized master equation for the Schrieffer-Wolff transformed Hamiltonian. We show that the decoherence, characterized through a relaxation $\tau_{r}$ and a dephasing time $\tau_{\phi}$, can be controlled through the external voltage and that the optimum point, where these times are maximum, is not necessarily in equilibrium. We outline the mechanism of this nonequilibrium-induced enhancement of lifetime and coherence. We discuss the relevance of our results for recent charge qubit experiments.Comment: 5 pages, 5 figure

It’s not all about the money—landowner motivation and high voltage grid development

The transition to a renewable energy future requires the extensive expansion of current high voltage grids. Due to the amount of land needed for expansion, issues related to land use have led to increased grid development opposition among landowners which in turn leads to significant project planning and budget overruns. Yet knowledge about why landowners support or object to high voltage grid development is limited. In this study, we use a theory on pluralism to uncover and categorize the multiplicity of motivations of 200 individual landowners in the Netherlands. Our results indicate that only a small number of landowners who oppose grid development focus on individual monetary gain through compensation for limits on their land use. Furthermore, most landowners find the fair and equal distribution of both the advantages and disadvantages of such limits more important than individual financial compensation. As such, overcoming contentious land use issues related to high voltage grid development by way of high individual financial compensation isn’t the only solution. Highlights: Land use conflicts affect expansions of high voltage grids crucial for meeting CO2 objectives Motivations of landowners are unevenly divided among different rationalities Most individual landowners do support high voltage grid developments Individual financial compensation isn’t the only solution

Strain engineering for GeSn/SiGeSn multiple quantum well laser structures

Optically pumped GeSn laser have been realized, thus alloying of group IV elements germanium (Ge) and tin (Sn) has a large potential to be a solution for Si-photonics, since a direct bandgap for Sn incorporations above ~9 at.% is obtained [1]. The value of the bandgap can further be controlled by adding Si into the mix, which can be exploited for the formation of heterostructures for carrier confinement [2]. However, a sufficiently large difference in energy ΔE between the indirect L-valley and the direct Г-valley is required to achieve room temperature lasing. Recently lasing was reported at 180K in GeSn alloys with Sn concentrations as high as 22,3% [3]. Alternatively ΔE can be increased by adding tensile strain to the GeSn layers. Here we will discuss that an appropriate combination of Sn concentration and strain will be advantageous to tailor gain and temperature stability of the structures. Please click Additional Files below to see the full abstract

The Hubbard Model at Infinite Dimensions: Thermodynamic and Transport Properties

We present results on thermodynamic quantities, resistivity and optical conductivity for the Hubbard model on a simple hypercubic lattice in infinite dimensions. Our results for the paramagnetic phase display the features expected from an intuitive analysis of the one-particle spectra and substantiate the similarity of the physics of the Hubbard model to those of heavy fermion systems. The calculations were performed using an approximate solution to the single-impurity Anderson model, which is the key quantity entering the solution of the Hubbard model in this limit. To establish the quality of this approximation we compare its results, together with those obtained from two other widely used methods, to essentially exact quantum Monte Carlo results.Comment: 29 pages, 16 figure

Kinetic model of II-VI(001) semiconductor surfaces: Growth rates in atomic layer epitaxy

We present a zinc-blende lattice gas model of II-VI(001) surfaces, which is investigated by means of Kinetic Monte Carlo (KMC) simulations. Anisotropic effective interactions between surface metal atoms allow for the description of, e.g., the sublimation of CdTe(001), including the reconstruction of Cd-terminated surfaces and its dependence on the substrate temperature T. Our model also includes Te-dimerization and the potential presence of excess Te in a reservoir of weakly bound atoms at the surface. We study the self-regulation of atomic layer epitaxy (ALE) and demonstrate how the interplay of the reservoir occupation with the surface kinetics results in two different regimes: at high T the growth rate is limited to 0.5 layers per ALE cycle, whereas at low enough T each cycle adds a complete layer of CdTe. The transition between the two regimes occurs at a characteristic temperature and its dependence on external parameters is studied. Comparing the temperature dependence of the ALE growth rate in our model with experimental results for CdTe we find qualitative agreement.Comment: 9 pages (REVTeX), 8 figures (EPS). Content revised, references added, typos correcte

Infinitesimal incommensurate stripe phase in an axial next-nearest-neighbor Ising model in two dimensions

An axial next-nearest-neighbor Ising (ANNNI) model is studied by using the non-equilibrium relaxation method. We find that the incommensurate stripe phase between the ordered phase and the paramagnetic phase is negligibly narrow or may vanish in the thermodynamic limit. The phase transition is the second-order transition if approached from the ordered phase, and it is of the Kosterlitz-Thouless type if approached from the paramagnetic phase. Both transition temperatures coincide with each other within the numerical errors. The incommensurate phase which has been observed previously is a paramagnetic phase with a very long correlation length (typically $\xi\ge 500$). We could resolve this phase by treating very large systems ($\sim 6400\times 6400$), which is first made possible by employing the present method.Comment: 12 pages, 10 figures. To appear in Phys.Rev.

Cyclotron effective masses in layered metals

Many layered metals such as quasi-two-dimensional organic molecular crystals show properties consistent with a Fermi liquid description at low temperatures. The effective masses extracted from the temperature dependence of the magnetic oscillations observed in these materials are in the range, m^*_c/m_e \sim 1-7, suggesting that these systems are strongly correlated. However, the ratio m^*_c/m_e contains both the renormalization due to the electron-electron interaction and the periodic potential of the lattice. We show that for any quasi-two-dimensional band structure, the cyclotron mass is proportional to the density of states at the Fermi energy. Due to Luttinger's theorem, this result is also valid in the presence of interactions. We then evaluate m_c for several model band structures for the \beta, \kappa, and \theta families of (BEDT-TTF)_2X, where BEDT-TTF is bis-(ethylenedithia-tetrathiafulvalene) and X is an anion. We find that for \kappa-(BEDT-TTF)_2X, the cyclotron mass of the \beta-orbit, m^{*\beta}_c, is close to 2 m^{*\alpha}_c, where m^{*\alpha}_c is the effective mass of the \alpha- orbit. This result is fairly insensitive to the band structure details. For a wide range of materials we compare values of the cyclotron mass deduced from band structure calculations to values deduced from measurements of magnetic oscillations and the specific heat coefficient.Comment: 12 pages, 3 eps figure

Formation of Small-Scale Condensations in the Molecular Clouds via Thermal Instability

A systematic study of the linear thermal instability of a self-gravitating magnetic molecular cloud is carried out for the case when the unperturbed background is subject to local expansion or contraction. We consider the ambipolar diffusion, or ion-neutral friction on the perturbed states. In this way, we obtain a non-dimensional characteristic equation that reduces to the prior characteristic equation in the non-gravitating stationary background. By parametric manipulation of this characteristic equation, we conclude that there are, not only oblate condensation forming solutions, but also prolate solutions according to local expansion or contraction of the background. We obtain the conditions for existence of the Field lengths that thermal instability in the molecular clouds can occur. If these conditions establish, small-scale condensations in the form of spherical, oblate, or prolate may be produced via thermal instability.Comment: 16 page, accepted by Ap&S