354 research outputs found
Vom alchemisten zum borsenspekulanten goethes "Faust" John Law und die moderne okonomie
No full textMoney and capital, Bd.8: bankers and financiers - socio aspects / A. Mosser, A. Teichova, R. Tilly and H. Wixforth
Rezensionen
No full textReviews on Dieter Engels (Hrsg.): 300 Jahre externe Finanzkontrolle in Deutschland - gestern, heute und morgen. Festschrift zur 300. Wiederkehr der Errichtung der Preußischen General-Rechenkammer (Andreas Thier); Joachim Scholtyseck: Die Geschichte der National-Bank 1921 bis 2011 (Harald Wixforth); Thorsten Beckers: Kapitalmarktpolitik im Wiederaufbau. Der westdeutsche Wertpapiermarkt zwischen Staat und Wirtschaft 1945-1957 (Friederike Sattler); Rudolf Bogensperger: Eine Sparkasse (nicht nur) für die Wiener. Die Geschäftspolitik der Zentralsparkasse der Gemeinde Wien im Kontext der Entwicklung des österreichischen Sparkassensektors (Christian Dirninger)
Standing surface acoustic waves in studied by time resolved X-ray diffraction at Petra III
No full textWe have carried out time resolved stroboscopic diffraction experiments on standing surface acoustic waves (SAWs) of Rayleigh type on a LiNbO3 substrate. A novel timing system has been developed and commissioned at the storage ring Petra III of Desy, allowing for phase locked stroboscopic diffraction experiments applicable to a broad range of timescales and experimental conditions. The combination of atomic structural resolution with temporal resolution on the picosecond time scale allows for the observation of the atomistic displacements for each time (or phase) point within the SAW period. A seamless transition between dynamical and kinematic scattering regimes as a function of the instantaneous surface amplitude induced by the standing SAW is observed. The interpretation and control of the experiment, in particular disentangling the diffraction effects (kinematic to dynamical diffraction regime) from possible non-linear surface effects is unambiguously enabled by the precise control of phase between the standing SAW and the synchrotron bunches. The example illustrates the great flexibility and universality of the presented timing system, opening up new opportunities for a broad range of time resolved experiments
Ausgaben der Länder in zukunftsorientierten Aufgabenbereichen
No full textSteuerungsrelevante und zukunftsorientierte Aufgabenbereiche der Länder wie die öffentliche Sicherheit, das Schulwesen oder die Infrastrukturausgaben haben in den letzten Jahren deutlich an Gewicht gewonnen. Allerdings gibt es kaum fundierte Analysen, da die statistischen Informationen dazu am aktuellen Rand nicht vorliegen. Um einen besseren Überblick zu erhalten, hat der Autor den Versuch unternommen, mithilfe der Meldungen der Länder zu den Kernhaushalten aktuelle Daten für die wichtigen Aufgabenbereiche aufzubereiten. Die Ergebnisse zeigen, dass sich die Länder in diesen Bereichen mehr engagiert haben als in der Öffentlichkeit wahrgenommen wird.In recent years, the German federal states (Länder) have increased their engagement in many policy areas at the centre of current public debate (e.g. public safety, education and infrastructure). However, this cannot be confi rmed using official data from the statistical office, since the annual statistics of expenditure and revenue - the only data source with this task reference - is current only through 2011. The author has tried to close this gap using data for the core budgets of the Länder which the national agency ha s not yet published. The results show that the Länder are more involved than widely perceived in all three functions of government examined here
Microfluidics for miniaturized laboratories on a chip
No full textMicrofluidic systems promise solutions for high throughput and highly specific analysis for biology, medicine and chemistry while consuming only tiny amounts of reactants and space. On these lab-on-a-chip platforms often multiple physical effects such as electrokinetic, acoustic or capillary phenomena from various disciplines are exploited to gain the optimal functionality. The fluidics on these small length scales differ significantly from our experience of the macroscopic world. In this Review we survey some of the approaches and techniques to handle minute amounts of fluid volumes in microfluidic systems with special focus on surface acoustic wave driven fluidics, a technique developed in our laboratory. Here, we outline the basics of this technique and demonstrate, for example, how acoustic mixing and fluid actuation is realized. Furthermore we discuss the interplay of different physical effects in microfluidic systems and illustrate their usefulness for several applications
Electronic and excitonic properties of self-assembled semiconductor quantum rings
No full textContains fulltext :
75794.pdf (Publisher’s version ) (Open Access
Time-resolved coherent X-ray diffraction imaging of surface acoustic waves
No full textTime-resolved coherent X-ray diffraction experiments of standing surface acoustic waves, illuminated under grazing incidence by a nanofocused synchrotron beam, are reported. The data have been recorded in stroboscopic mode at controlled and varied phase between the acoustic frequency generator and the synchrotron bunch train. At each time delay (phase angle), the coherent far-field diffraction pattern in the small-angle regime is inverted by an iterative algorithm to yield the local instantaneous surface height profile along the optical axis. The results show that periodic nanoscale dynamics can be imaged at high temporal resolution in the range of 50 ps (pulse length). (C) 2014 International Union of Crystallograph
Theory of the electronic states of semiconductor heterostructures
No full textThis thesis is concerned with theoretical calculations of the properties of electronic bound states in semiconductor heterostructures. The complex band structure empirical pseudopotential method (EPM) is used as the foundation of the work. Spin orbit coupling and strain effects (due to lattice mismatch) are included in familiar ways, as is the transfer matrix method, allowing the study of arbitrarily configured heterostructures. These techniques are used to investigate the unusually deep InAs/AlSb conduction band well. The strong possibility of intraband transitions at electro magnetic wavelengths around 1.55µm is predicted, with corresponding enhanced momentum matrix elements and joint density of states over interband transitions. An InAs/GaSb/AlSb asymmetric well is investigated, paying particular attention to the bound states in the vicinity of the InAs/GaSb band overlap. The electron-like states are found to cross with heavy hole and anti-cross with light hole-like states, as a function of heterostructure dimension or applied electrostatic field. This is analogous to the hybridisation of states in the in-plane band structure, except that for zero in-plane wave vector there can be no appreciable hybridisation of electron and heavy hole states. A technique is described that has been developed to extract envelope functions from heterostructure wavefunctions calculated using the realistic complex band structure EPM approach. These envelope functions conform to Burt’s theory (M. G. Burt, J. Phys.: Condens. Matt. 4, 6651 (1992)) in that they are uniquely defined, continuous and smooth over all space. Comparisons with traditional effective mass envelope functions are made. The extracted envelope functions are used to demonstrate conclusively Burt's predictions (M. G. Burt, Superlatt. Mi- crostruct. 17, 335 (1995)) concerning the inadequacy of certain approximations for the calculation of interband dipole matrix elements and charge oscillation. Finally, the issue of k • p operator ordering is convincingly settled, in favour of 'ordered' over 'symmetrised' Hamiltonians, by comparison to EPM calculations, and using EPM derived k • p parameters
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