@inproceedings{997, author = {{Carlson, Emma and Karl, Holger and Wolisz, Adam and Prehofer, Christian}}, booktitle = {{Proc. European Wireless}}, location = {{Barcelona/Spain}}, title = {{{Distributed allocation of time slots for real-time traffic in a wireless multi-hop network}}}, year = {{2004}}, } @article{998, author = {{Mengesha, Seble and Karl, Holger and Wolisz, Adam}}, journal = {{Proc. of MedHocNet 2004}}, title = {{{Capacity increase of multi-hop cellular wlans exploiting data rate adaptation and frequency recycling}}}, year = {{2004}}, } @article{4160, author = {{Hehenkamp, Burkhard and Leininger, W. and Possajennikov, A.}}, issn = {{0176-2680}}, journal = {{European Journal of Political Economy}}, number = {{4}}, pages = {{1045--1057}}, publisher = {{Elsevier BV}}, title = {{{Evolutionary equilibrium in Tullock contests: spite and overdissipation}}}, doi = {{10.1016/j.ejpoleco.2003.09.002}}, volume = {{20}}, year = {{2004}}, } @article{4270, abstract = {{The adiabatic driving of the resonant electron dynamics in a one-dimensional resonant photonic band gap is proposed as an optical mechanism for nonlinear ultrafast switching. Pulsed excitation inside the photonic gap results in an ultrafast suppression and recovery of the gap. This behavior results from the adiabatic carrier dynamics due to rapid radiative damping inside the band gap.}}, author = {{Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Prineas, John P. and Nielsen, Nils C. and Kuhl, Jürgen and Khitrova, Galina and Gibbs, Hyatt M. and Giessen, Harald and Koch, Stephan W.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{23}}, publisher = {{American Physical Society (APS)}}, title = {{{Adiabatically driven electron dynamics in a resonant photonic band gap: Optical switching of a Bragg periodic semiconductor}}}, doi = {{10.1103/physrevb.70.233302}}, volume = {{70}}, year = {{2004}}, } @article{4274, abstract = {{We present a theory of the optical line shape of coherent intersubband transitions in a semiconductor quantum well, considering non-Markovian LO-phonon scattering as major broadening mechanism. We show that a quantum kinetic approach leads to additional polaron resonances and a resonance enhancement for gap energies close to the phonon energy.}}, author = {{Butscher, S. and Förstner, Jens and Waldmüller, I. and Knorr, A.}}, issn = {{0370-1972}}, journal = {{physica status solidi (b)}}, keywords = {{tet_topic_qw}}, number = {{11}}, pages = {{R49--R51}}, publisher = {{Wiley}}, title = {{{Polaron signatures in the line shape of semiconductor ;intersubband transitions: quantum kinetics of the electron–phonon interaction}}}, doi = {{10.1002/pssb.200409053}}, volume = {{241}}, year = {{2004}}, } @article{4277, abstract = {{We investigate the temporal and spectral properties of subpicosecond pulses transmitted on the heavy-hole exciton transition through a multiple-quantum-well Bragg structure, exhibiting a one-dimensional photonic band gap. At low light intensities, a temporal propagation beating is observed. This beating is strongly dependent on the optical dephasing time T2 which is dominated by the radiative interwell coupling. In an intermediate intensity regime, the Pauli-blocking nonlinearity leads to gradual suppression of the photonic band gap and vanishing of the linear propagation beating. For highly nonlinear excitation, we find signatures of selfinduced transmission due to Rabi flopping and adiabatic following of the carrier density. Numerical simulations using the semiconductor Maxwell-Bloch equations are in excellent agreement with the experimental data up to intensities for which higher many-particle correlations become more important and self-phase modulation occurs in the sample substrate.}}, author = {{Nielsen, N. C. and Kuhl, J. and Schaarschmidt, M. and Förstner, Jens and Knorr, A. and Koch, S. W. and Khitrova, G. and Gibbs, H. M. and Giessen, H.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qw}}, number = {{7}}, publisher = {{American Physical Society (APS)}}, title = {{{Linear and nonlinear pulse propagation in a multiple-quantum-well photonic crystal}}}, doi = {{10.1103/physrevb.70.075306}}, volume = {{70}}, year = {{2004}}, } @inproceedings{4279, abstract = {{We demonstrate temporal and spatial pulse compression and modulational instabilities in the nonlinear defocusing regime near the band edge of bulk GaAs. Experiment and theory show that spatiotemporal coupling is responsible for these surprising phenomena.}}, author = {{Nielsen, Nils. C. and Siederdissen, Tilmann H. zu and Kuhl, Jürgen and Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Koch, Stephan W. and Giessen, Harald }}, booktitle = {{International Conference on Ultrafast Phenomena 2004}}, isbn = {{3-54024-110-8}}, keywords = {{tet_topic_polariton}}, location = {{Niigata (Japan)}}, publisher = {{Technical Digest (CD) (Optical Society of America, 2004)}}, title = {{{Subpicosecond spatiotemporal pulse compression in a nonlinear defocusing material}}}, year = {{2004}}, } @inproceedings{4280, abstract = {{Theoretically and experimentally, we investigate temporal phase evolution during Rabi-flopping on the A-exciton resonance in CdSe using a novel fast-scanning XFROG method and observe phase changes smaller than π/2 compared to the slightly-chirped input pulse.}}, author = {{Höner zu Siederdissen, Tilman and Nielsen, Nils Christian. and Kuhl, Jürgen and Förstner, Jens and Knorr, Andreas and Giessen, Harald}}, booktitle = {{International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-770-9}}, keywords = {{tet_topic_qd}}, location = {{San Francisco, California (USA)}}, publisher = {{OSA}}, title = {{{Temporal phase evolution during excitonic Rabi flopping in semiconductors}}}, doi = {{10.1364/iqec.2004.imb3}}, year = {{2004}}, } @inproceedings{4281, abstract = {{The coupled spatiotemporal characteristics of subpicosecond pulses propagating in the nonlinear defocusing regime near the band edge of bulk GaAs are investigated experimentally and theoretically. We demonstrate pulse compression both in time and transverse space.}}, author = {{Nielsen, Nils C. and Kuhl, Jürgen and Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Koch, Stephan W. and Giessen, Harald }}, booktitle = {{Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-770-9}}, keywords = {{tet_topic_polariton}}, location = {{San Francisco, California (USA)}}, publisher = {{Technical Digest (CD) (Optical Society of America, 2004)}}, title = {{{Temporal and spatial compression of near-resonant pulses in a nonlinear defocusing semiconductor }}}, year = {{2004}}, } @inproceedings{4282, abstract = {{We investigate theoretically the ultrafast nonlinear suppression of the resonant photonic band gap by strong laser pulses in semiconductor multiple qnantum wells. We achieve good agreement with our measurements on reflection samples.}}, author = {{Schaarschmidt, Martin and Förstner, Jens and Knorr, Andreas and Prineas, John P. and Nielsen, Nils C. and Kuhl, Jürgen and Kithrova, Galina and Gibbs, Hyatt M. and Giessen, Harald and Koch, Stephan W.}}, booktitle = {{Conference on Lasers and Electro-Optics/International Quantum Electronics Conference and Photonic Applications Systems Technologies}}, isbn = {{1-55752-778-4 }}, keywords = {{tet_topic_qw}}, location = {{San Francisco, California (USA) }}, publisher = {{OSA}}, title = {{{Nonlinear light pulse propagation in Bragg-periodic multiple semiconductor quantum well samples: ultrafast switching of a resonant photonic band gap}}}, doi = {{10.1364/iqec.2004.iwa3}}, year = {{2004}}, } @inbook{4286, abstract = {{Due to their many-particle character and their application in quantum cascade lasers, optical intersubband excitations in semiconductor quantum wells have become the focus of many recent publications [1,2]. In samples of high quality, intrinsic processes like electron-electron and electron-phonon many particle correlations determine the basic optical and transport properties such as lineshape and ultrafast dynamics. At the same time, intersubband excitations allow the direct investigation of dynamical properties of an important model system of many particle physics - the two-dimensional electron gas. We here present a microscopic theory for the intersubband dynamics and absorption. The calculation of absorption spectra of MQW systems is in principle composed of two parts: the determination of the polarization in a single quantum well within a density matrix approach as the source of electromagnetic radiation (Fig. 1a) and the calculation of the generated fields in the geometry of interest (Fig. 1b) within a Green's function approach [3,4]. We will here focus on the so-called single-pass geometry (cf. Fig. 1b, [5]).}}, author = {{Waldmüller, Ines and Förstner, Jens and Knorr, Andreas }}, booktitle = {{Nonequilibrium Physics at Short Time Scales}}, editor = {{Morawetz, Klaus}}, isbn = {{9783642057458}}, keywords = {{tet_topic_qw}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Self-consistent Projection Operator Theory of Intersubband Absorbance in Semiconductor Quantum Wells}}}, doi = {{10.1007/978-3-662-08990-3}}, year = {{2004}}, } @phdthesis{4319, abstract = {{In dieser Arbeit wird eine Theorie vorgestellt, welche die quantenmechanische Vielteilchenphysik der Licht-Materie Wechselwirkung in Halbleiternanostrukturen beschreibt. Diese mikroskopische Beschreibung wird durch Kombination eines allgemeinen Dichtematrixansatzes mit speziellen Methoden zur Auswertung der Maxwellgleichungen wie der zeitaufgelösten Finite-Differenzen-Methode (FDTD) erreicht. Die Theorie wird auf verschiedene physikalische Situationen angewendet, wie z.B. Lichtausbreitung in Volumenhalbleitern, Interband- und Intersubbandübergänge in Quantenfilmstrukturen und optische Anregung von Quantenpunkten. Der Fokus liegt dabei auf der Beschreibung der linearen und nichtlinearen Antwort des Vielteilchensystems und seiner Ankopplung an das elektromagnetische Feld. In diesem Zusammenhang wird sowohl die Erzeugung als auch der Zerfall von optischen Anregungen untersucht, indem verschiedene Kopplungsmechanismen wie Elektron-Phonon-, Elektron-Photon- und Elektron-Elektron-Wechselwirkung berücksichtigt werden. Im Bereich der linearen Optik, also für Anregung mit geringer Intensität, ermöglicht die Theorie die Berechnung von Absorptionsspektren. Verschiedene Effekte in linearer Optik werden in dieser Arbeit untersucht und beschrieben: Linienaufspaltung durch Polaritonen im Volumenmaterial, Zunahme der Linienbreite bei Intersubbandübergängen verursacht durch Elektron-Elektron- und Elektron- Phonon-Streuung in einzelnen Quantenfilmen, Bildung einer optischen Bandlücke durch starke radiative Kopplung in Vielfilmstrukturen in Bragg-Geometrie, Phononenseitenbänder verursacht durch quantenkinetische Effekte in einzelnen Quantenpunkten und schliesslich Superradianz und Interferenzeffekte in Quantenpunktgittern. Bei nichtlinearer Anregung treten Dichte-Rabiflops als fundamentale Prozesse in allen betrachteten Systemen auf und können als kohärente Be- und Entvölkerung von quantenmechanischen Zuständen beobachtet werden. Der Einfluss von starker Lichtkopplung und verschiedenen Wechselwirkungen auf dynamische Größen wie die Besetzung wird untersucht. Bei nichtlinearer Propagation, bei der sich ein starker Lichtpuls über längere Strecken in einem System bewegt, wird selbstinduzierte Verstärkung der Transmission näher betrachtet. Des weiteren werden von der Coulombwechselwirkung verursachte nichtlineare Effekte wie exzitoninduziertes Dephasieren in Volumenmaterial und verschränkte Zustände in Quantenpunkten untersucht, die einen Zusammenbruch der Hartree-Fock- Näherung darstellen. Zusammenfassend werden in dieser Arbeit verschiedene lineare und nichtlineare optische Effekte in Halbleiternanostrukturen verschiedener Dimensionalität mit Hilfe einer allgemeinen Theorie, die einen Dichtematrixansatz mit den Maxwellschen Gleichungen kombiniert, untersucht.}}, author = {{Förstner, Jens}}, keywords = {{tet_topic_qd, tet_topic_qw, tet_topic_phc}}, title = {{{Light Propagation and Many-Particle Effects in Semiconductor Nanostructures}}}, doi = {{10.14279/depositonce-999}}, year = {{2004}}, } @article{5596, author = {{Kabst, Rüdiger}}, journal = {{ International Journal of Human Resource Management.}}, number = {{1}}, pages = {{1--16}}, title = {{{Human Resource Management for International Joint Ventures: Expatriation and Selective Control}}}, volume = {{15}}, year = {{2004}}, } @article{5601, author = {{Weber, W and Kabst, Rüdiger}}, journal = {{Management Revue: The International Review of Management Studies. }}, number = {{2}}, pages = {{271--278}}, title = {{{Human Resource Management: The Need for Theory and Diversity}}}, volume = {{15}}, year = {{2004}}, } @article{5662, abstract = {{Spam als unerwünschte Massen-E-Mail hat die Grenze von der Belästigung zur ökonomischen Relevanz längst überschritten. Ihr relativer Anteil am gesamten, weltweiten E-Mail-Aufkommen stieg in den vergangenen Jahren auf mehr als 50% im Jahr 2003. Es entstehen jährlich volkswirtschaftliche Schäden in Milliardenhöhe. Zur Bekämpfung des Spam-Problems werden neben gesetzlichen Regelungen vor allem technische Lösungen eingesetzt, bei denen das Blockieren und Filtern von E-Mails in praktisch eingesetzten Anti-Spam-Systemen dominieren. Dieser Artikel führt in die Spam-Problematik ein und beschreibt, bewertet und klassifiziert die derzeit bedeutendsten Verfahren zur Bekämpfung von Spam.}}, author = {{Schryen, Guido}}, journal = {{Wirtschaftsinformatik}}, keywords = {{Spam, E-Mail, Spoofing, Blockieren, Filtern, Lightweight Mail Transfer Agent Authentication Protocol (LMAP)}}, number = {{4}}, pages = {{281--288}}, publisher = {{Springer}}, title = {{{Effektivität von Lösungsansätzen zur Bekämpfung von Spam}}}, volume = {{46}}, year = {{2004}}, } @inproceedings{5663, abstract = {{Spam as unsolicited e-mail to a large number of recipients is known to ecome an increasingly disturbing and costly issue of electronic business and internet traffic. Mainly technical-oriented approaches are applied with a focus on blocking, filtering, and authentication mechanisms based on the domain name system. They come along with different drawbacks and have all low effectiveness in common. The article sketches these approaches, shows its limitations, and proposes an account-based approach where the number of e-mails per day and account is restricted.}}, author = {{Schryen, Guido}}, booktitle = {{Proceedings of the IADIS International Conference WWW/Internet 2004. vol. 2}}, editor = {{Isaias, Pedro}}, keywords = {{e-mail, spam, filtering, blocking, LMAP, SMTP account}}, pages = {{937--940}}, publisher = {{IADIS Press}}, title = {{{Fighting Spam: Motivating an Account-based Approach}}}, year = {{2004}}, } @inproceedings{5664, abstract = {{Remote Internet voting systems still suffer from many security problems which rely on the clients, the servers, and the network connections. Denial-ofservice attacks and viruses still belong to the most challenging security issues. Projects and studies like the ?Voting Technology Project? of CALTECH and MIT or SERVE of the US Department of Defense set up to gain experience evidence many of the notional weaknesses of current Internet voting systems.}}, author = {{Schryen, Guido}}, booktitle = {{Workshop of the ESF TED Programme}}, pages = {{121--131}}, title = {{{How Security Problems Can Compromise Remote Internet Voting Systems}}}, year = {{2004}}, } @inbook{5666, author = {{Schryen, Guido}}, booktitle = {{Digitale Teilung - digitale Integration : Perspektiven der Internetnutzung}}, editor = {{Gehrke, Gernot}}, pages = {{45--51}}, publisher = {{KOPAED-Verlag}}, title = {{{Neulich am Hotspot - Bringt Mobiles Internet die Menschen ins Netz?}}}, year = {{2004}}, } @article{6486, author = {{Deißinger, T. and Kremer, H.-Hugo}}, journal = {{Erziehungswissenschaft und Beruf}}, number = {{2}}, pages = {{163--175}}, title = {{{Das Praxissemester im Rahmen des Diplomstudiengangs Wirtschaftspädagogik an der Universität Konstanz - Organisation und didaktische Ausrichtung}}}, year = {{2004}}, } @inbook{6487, author = {{Kremer, H.-Hugo}}, booktitle = {{Studien zur Dynamik des Berufsbildungssystems. Forschungsbeiträge zur Struktur-, Organisations- und Curriculumentwicklung}}, editor = {{Reinisch, H. and Eckert, M. and Tramm, T.}}, pages = {{189--202}}, title = {{{Virtuelle Foren - Konsequenzen für Forschung und Entwicklung}}}, year = {{2004}}, }