Inverting the regulatory rules? Optimizing airport regulation to account for commercial revenues

This paper analyzes the role of commercial revenues in today's airport regulatory system. We find that the current regulatory regime only partially achieves core aims such as welfare maximization. After highlighting instances in which airport price regulation is not economically justified, we explore the potential for airports to exercise market power in the commercial sector. In certain circumstances, we advocate the introduction of an 'inverted' dual till system under which commercial as opposed to aviation revenues are the focus of price regulation. The suitability of such a system varies from airport to airport, however, depending on various factors, such as the airport's competitive environment and the presence of capacity constraints. --Airport regulation,non-aviation revenues,price differentiation,single till,dual till

InN dielectric function from the midinfrared to the visible range

The dispersion of the dielectric function for wurtzite InN is analytically evaluated in the region near the fundamental energy gap. The real part of the dielectric function has a logarithmic singularity at the absorption edge. This results in the large contribution into the optical dielectric constant. For samples with degenerate carriers, the real part of the dielectric function is divergent at the absorption edge. The divergence is smeared with temperatures or relaxation rate. The imaginary part of the dielectric function has a plateau far away from the absorption onset.Comment: 5 pages, 2 figure

Inverting the regulatory rules? Optimizing airport regulation to account for commercial revenues

This paper analyzes the role of commercial revenues in today's airport regulatory system. We find that the current regulatory regime only partially achieves core aims such as welfare maximization. After highlighting instances in which airport price regulation is not economically justified, we explore the potential for airports to exercise market power in the commercial sector. In certain circumstances, we advocate the introduction of an 'inverted' dual till system under which commercial as opposed to aviation revenues are the focus of price regulation. The suitability of such a system varies from airport to airport, however, depending on various factors, such as the airport's competitive environment and the presence of capacity constraints

Fixation principles in metaphyseal bone—a patent based review

Osteoporotic changes start in cancellous bone due to the underlying pathophysiology. Consequently, the metaphyses are at a higher risk of "osteoporotic” fracture than the diaphysis. Furthermore, implant purchase to fix these fractures is also affected by the poor bone quality. In general, researchers and developers have worked on three different approaches to address the problem of fractures to osteoporotic bone: adapted anchoring techniques, improved load distribution as well as transfer with angular stable screws, and augmentation techniques using bone substitutes. A patent-based review was performed to evaluate which ideas were utilized to improve fixation in osteoporotic, metaphyseal bone, especially in the proximal femur, and to analyze whether the concept had entered clinical use. Anchoring devices that are either extramedullary or intramedullary have a long clinical history. However, demanding surgical techniques and complications, especially in poor quality bone, are justification that such implants and their corresponding surgical techniques need to be improved upon. Expanding elements have been evaluated in the laboratory. The results are promising and the potential of this approach has yet to be fully exploited in the clinics. Internal fixators with angular stable screws open the door for many new anchorage ideas and have great potential for further optimization of load distribution and transfer. Augmentation techniques may improve anchorage in osteoporotic bone. However, the properties of bone substitute materials will need to be modified and improved upon in order to meet the demanding requirements. If we summarise the development process and the clinical use of implants to date, we have to clearly state that more factors than simply biomechanical advantage will determine the clinical success of a new fixation principle or a new implant. Instead, fracture treatment of patients with osteoporosis really needs an interdisciplinary approach

Translation-Based Dictionary Alignment for Under-Resourced Bantu Languages

Despite a large number of active speakers, most Bantu languages can be considered as under- or less-resourced languages. This includes especially the current situation of lexicographical data, which is highly unsatisfactory concerning the size, quality and consistency in format and provided information. Unfortunately, this does not only hold for the amount and quality of data for monolingual dictionaries, but also for their lack of interconnection to form a network of dictionaries. Current endeavours to promote the use of Bantu languages in primary and secondary education in countries like South Africa show the urgent need for high-quality digital dictionaries. This contribution describes a prototypical implementation for aligning Xhosa, Zimbabwean Ndebele and Kalanga language dictionaries based on their English translations using simple string matching techniques and via WordNet URIs. The RDF-based representation of the data using the Bantu Language Model (BLM) and - partial - references to the established WordNet dataset supported this process significantly

Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

The characteristics of the excitonic absorption and emission around the fundamental bandgap of wurtzite Mg(x)Zn(1-x)O grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy with Mg contents between x = 0 and x = 0.23 are studied using spectroscopic ellipsometry and photoluminescence (PL) measurements. The ellipsometric data were analyzed using a multilayer model yielding the dielectric function (DF). The imaginary part of the DF for the alloys exhibits a pronounced feature which is attributed to exciton-phonon coupling (EPC) similar to the previously reported results for ZnO. Thus, in order to determine reliable transition energies, the spectral dependence is analyzed by a model which includes free excitonic lines, the exciton continuum, and the enhanced absorption due to EPC. A line shape analysis of the temperature-dependent PL spectra yielded in particular the emission-related free excitonic transition energies, which are compared to the results from the DF line-shape analysis. The PL linewidth is discussed within the framework of an alloy disorder model

Electroreflectance characterization of AlInGaN/GaN high-electron mobility heterostructures

Room temperature electroreflectance (ER) spectroscopy has been used to study the fundamental properties of AlxInyGa${}_{1-x-y}$N/AlN/GaN heterostructures under different applied bias. The (0001)-oriented heterostructures were grown by metal-organic vapor phase epitaxy on sapphire. The band gap energy of the AlxInyGa${}_{1-x-y}{\rm{N}}$ layers has been determined from analysis of the ER spectra using Aspnes' model. The obtained values are in good agreement with a nonlinear band gap interpolation equation proposed earlier. Bias-dependent ER allows one to determine the sheet carrier density of the two-dimensional electron gas and the barrier field strength

Universality of electron accumulation at wurtzite c- and a-plane and zinc-blende InN surfaces

Electron accumulation is found to occur at the surface of wurtzite (112¯0), (0001), and (0001¯) and zinc-blende (001) InN using x-ray photoemission spectroscopy. The accumulation is shown to be a universal feature of InN surfaces. This is due to the low Г-point conduction band minimum lying significantly below the charge neutrality level

Luminescence from two-dimensional electron gases in InAlN/GaN heterostructures with different In content

The luminescence properties of InxAl1−xN/GaN heterostructures are investigated systematically as a function of the In content (x = 0.067 − 0.208). The recombination between electrons confined in the two-dimensional electron gas and free holes in the GaN template is identified and analyzed. We find a systematic shift of the recombination with increasing In content from about 80 meV to only few meV below the GaN exciton emission. These results are compared with model calculations and can be attributed to the changing band profile and originating from the polarization gradient between InAlN and GaN

A Look Into Homomorphic Cryptography and the BV Homomorphic Encryption Scheme

Vi tar en titt på det homomorfiske kryptosystemet BV og ser i tillegg på sikkerhets-, korrekthets- of compakthets-bevis for dette som et eksempel på hvordan man driver med homomorfisk kryptografi og hvordan man kan skrive bevis i feltet. Vi utvider bevisene i den opprinnelige artikkelen i et forsøk om å gjøre dem lettere å følge.We take a look at the BV homomorphic encryption scheme and security, correctness, and compactness proofs for this encryption scheme as an example of how homomorphic encryption is done, and how proofs in the field are written. We expand the proofs in the original paper in an attempt to make the arguments easier to follow