Adlayer core-level shifts of admetal monolayers on transition metal substrates and their relation to the surface chemical reactivity

Using density-functional-theory we study the electronic and structural properties of a monolayer of Cu on the fcc (100) and (111) surfaces of the late 4d transition metals, as well as a monolayer of Pd on Mo bcc(110). We calculate the ground states of these systems, as well as the difference of the ionization energies of an adlayer core electron and a core electron of the clean surface of the adlayer metal. The theoretical results are compared to available experimental data and discussed in a simple physical picture; it is shown why and how adlayer core-level binding energy shifts can be used to deduce information on the adlayer's chemical reactivity.Comment: RevTeX, 7 pages, 2 figure

Satellite system performance assessment for in-flight entertainment and air traffic control

Concurrent satellite systems have been proposed for IFE (In-Flight Entertainment) communications, thus demonstrating the capability of satellites to provide multimedia access to users in aircraft cabin. At the same time, an increasing interest in the use of satellite communications for ATC (Air Traffic Control) has been motivated by the increasing load of traditional radio links mainly in the VHF band, and uses the extended capacities the satellite may provide. However, the development of a dedicated satellite system for ATS (Air Traffic Services) and AOC (Airline Operational Communications) seems to be a long-term perspective. The objective of the presented system design is to provide both passenger application traffic access (Internet, GSM) and a high-reliability channel for aeronautical applications using the same satellite links. Due to the constraints in capacity and radio bandwidth allocation, very high frequencies (above 20 GHz) are considered here. The corresponding design implications for the air interface are taken into account and access performances are derived using a dedicated simulation model. Some preliminary results are shown in this paper to demonstrate the technical feasibility of such system design with increased capacity. More details and the open issues will be studied in the future of this research work

Tiberio Claudio Donato e i "progymnasmata"

pp. 177-199Le Interpretationes Vergilianae di Tiberio Claudio Donato rappresentano una interessante strumento per studiare la diffusione e la proposizione dei progymnasmata nella metà latina dell’Impero poiché integrano, seppur in modo parziale, le scarse informazioni offerte in proposito dalla letteratura manualistica, quasi completamente perduta. In particolare, attraverso un’analisi mirata delle ricorrenze del locus communis, sono stati individuati due differenti impieghi di questo e degli altri esercizi preliminari: uno ‘esegetico’, vale a dire un uso consapevole di questa categoria retorica come strumento di critica letteraria, e uno ‘letterario’, ossia un ricorso – spesso dissimulato – ai progymnasmata come modello formale di composizione artistica. Questo secondo aspetto permette di comprendere, almeno in parte, alcune tendenze letterarie proprie del periodo tardoantico.The work of Tiberius Claudius Donatus represents an interesting tool for study the spreading of progymnasmata in the latin part of Empire, because they integrate, even though partially, the few informations we have about ‘handbook literature’, almost completely lost. In particular, through an analisys of recurrences of the locus communis, it is possible to single out two different uses of this one and others preliminary exercises: the first ‘exegetic’, i.e. a conscius use of this retorical category as a tool of literary criticism; the second ‘literary’, i.e. a use of progymnasmata, often dissimulated, as a formal model of artistic composition

Cursim scripsi quae potui: Tiberio Claudio Donato rilegge il suo "libro"

This paper contains a detailed analysis of the final epistle of Tiberius Claudius Donatus’ Interpretationes Vergilianae, addressed to his son Donatianus. Through a comparison with Verg. Aen. VII 641-646 (and Donatus’ interpretation of these lines) it is possible to argue that Donatus was envisioning this epistle as the conclusion of a long work (the commentary itself) and the starting point of a new endeavour: the writing of a thirteenth book covering all the Realien of the Aeneid

Comparing building blocks of life: sequence alignment and evaluation of predicted structural and functional features

Heringa, J. [Promotor]Feenstra, K.A. [Copromotor

Does one size fit all at all times ? The role of country specificities and state dependencies in predicting banking crises. National Bank of Belgium Working Paper No. 297

Given the indisputable cost of policy inaction in the run-up to banking crises as well as the negative side effects of unwarranted policy activation, policymakers would strongly benefit from early-warning thresholds that more accurately predict crises and produce fewer false alarms. This paper presents a novel yet intuitive methodology to compute country-specific and state-dependent thresholds for early-warning indicators of banking crises. Our results for a selection of early-warning indicators for banking crises in 14 EU countries show that the benefits of applying the conditional moments approach can be substantial. The methodology provides more robust signals and improves the early-warning performance at the country-specific level, by accounting for country idiosyncrasies and state dependencies, which play an important role in national supervisory authorities’ macroprudential surveillance

Determination of the strange-quark mass from QCD pseudoscalar sum rules

A new determination of the strange-quark mass is discussed, based on the two-point function involving the axial-vector current divergences. This Green function is known in perturbative QCD up to order O(alpha_s^3), and up to dimension-six in the non-perturbative domain. The hadronic spectral function is parametrized in terms of the kaon pole, followed by its two radial excitations, and normalized at threshold according to conventional chiral-symmetry. The result of a Laplace transform QCD sum rule analysis of this two-point function is: m_s(1 GeV^2) = 155 pm 25 MeV.Comment: Invited talk given by CAD at QCD98, Montpellier, July 1998. To appear in Nucl.Phys.B Proc.Suppl. Latex File. Four (double column) page

Volcano: An interactive sword generator

In this work, we introduce Volcano, a tool for the procedural generation of 3D models of swords. Unlike common procedural content generation tools, it exploits interactive evolution to reduce as much as possible the effort of the users during the generation process. Indeed, Volcano allows to forge the desired type of swords through a rather simple visual exploration of the design space. The 3D models generated with the tool can be directly used as game assets or further developed with a standard modeling software. A prototype of Volcano was tested by 30 users, including both students and game developers. The feedbacks received are very positive: tools like Volcano might be useful both for players, to create user contents, and for developers, to speed-up the design of game contents

Enhanced oxidation activity from modified ceria: MnOx-ceria, CrOx-ceria and Mg doped VOx-ceria

Ceria is an important component of catalysts for oxidation reactions that proceed through the Mars-van Krevelen mechanism, promoting activity. A paradigm example of this is the VOx–CeO2 system for oxidative dehydrogenation reactions, where vanadium oxide species are supported on ceria and a special synergy between them is behind the enhanced activity: reduction of the catalyst is promoted by ceria undergoing reduction. This leads to favourable oxygen vacancy formation and hydrogen adsorption energies—useful descriptors for the oxidation activity of VOx–CeO2 catalysts. In this paper, we examine if this promoting effect on ceria-based catalysts holds for other metal oxide modifiers and we investigate MnOn– and CrOn–CeO2(111) (n = 0 − 4) as examples. We show, combining density functional theory calculations and statistical thermodynamics that similarly to the vanadia modifier, the stable species in each case is MnO2– and CrO2–CeO2. Both show favourable energetics for oxygen vacancy formation and hydrogen adsorption, indicating that VO2–CeO2 is not the only system of this type that can have an enhanced activity for oxidation reactions. However, the mechanism involved in each case is different: CrO2–CeO2 shows similar properties to VO2–CeO2 with ceria reduction upon oxygen removal stabilising the 5+ oxidation state of Cr. In contrast, with MnO2–CeO2, Mn is preferentially reduced. Finally, a model system of VO2–Mg:CeO2 is explored that shows a synergy between VO2 modification and Mg doping. These results shed light on the factors involved in active oxidation catalysts based on supported metal oxides on ceria that should be taken into consideration in a rational design of such catalysts