@inproceedings{2023, author = {{Awerbuch, Baruch and Scheideler, Christian}}, booktitle = {{Proceedings of the Twenty-Sixth Annual ACM Symposium on Principles of Distributed Computing, PODC 2007, Portland, Oregon, USA, August 12-15, 2007}}, isbn = {{978-1-59593-616-5}}, pages = {{370----371}}, publisher = {{ACM}}, title = {{{A denial-of-service resistant DHT}}}, doi = {{10.1145/1281100.1281178}}, year = {{2007}}, } @inbook{3002, author = {{Blömer, Johannes and Krummel, Volker}}, booktitle = {{Selected Areas in Cryptography}}, isbn = {{9783540773597}}, pages = {{96--109}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Analysis of Countermeasures Against Access Driven Cache Attacks on AES}}}, doi = {{10.1007/978-3-540-77360-3_7}}, year = {{2007}}, } @book{1106, author = {{Geierhos, Michaela}}, publisher = {{Ludwig-Maximilians-Universität}}, title = {{{Grammatik der Menschenbezeichner in biographischen Kontexten}}}, volume = {{2}}, year = {{2007}}, } @article{18591, abstract = {{Using density-functional theory, we investigate the stability of the half-metallic ground state of magnetite under different strain conditions. The effects of volume relaxation and internal degrees of freedom are fully taken into account. For hydrostatic compression, planar strain in the (001) plane and uniaxial strain along the [001] direction, we derive quantitative limits beyond which magnetite becomes metallic. As a major new result, we identify the bond length between the octahedrally coordinated iron atoms and their neighbouring oxygen atoms as the main characteristic parameter, and we show that the transition occurs if external strain reduces this interatomic distance from 2.06 Å in equilibrium to below a critical value of 1.99 Å. Based on this criterion, we also argue that planar strain due to epitaxial growth does not lead to a metallic state for magnetite films grown on (111)-oriented substrates.}}, author = {{Friák, Martin and Schindlmayr, Arno and Scheffler, Matthias}}, issn = {{1361-6633}}, journal = {{New Journal of Physics}}, number = {{1}}, publisher = {{IOP Publishing and Deutsche Physikalische Gesellschaft}}, title = {{{Ab initio study of the half-metal to metal transition in strained magnetite}}}, doi = {{10.1088/1367-2630/9/1/005}}, volume = {{9}}, year = {{2007}}, } @inproceedings{2214, abstract = {{We present a randomized block-level storage virtualization for arbitrary heterogeneous storage systems that can distribute data in a fair and redundant way and can adapt this distribution in an efficient way as storage devices enter or leave the system. More precisely, our virtualization strategies can distribute a set of data blocks among a set of storage devices of arbitrary non-uniform capacities so that a storage device representing x% of the capacity in the system will get x% of the data (as long as this is in principle possible) and the different copies of each data block are stored so that no two copies of a data block are located in the same device. Achieving these two properties is not easy, and no virtualization strategy has been presented so far that has been formally shown to satisfy fairness and redundancy while being time- and space-eflcient and allowing an efficient adaptation to a changing set of devices.}}, author = {{Brinkmann, André and Effert, Sascha and Meyer auf der Heide, Friedhelm and Scheideler, Christian}}, booktitle = {{IEEE International Conference on Distributed Computing Systems (ICDCS)}}, title = {{{Dynamic and redundant data placement}}}, year = {{2007}}, } @techreport{6287, abstract = {{Spamming remains a form of Internet abuse, which burdens the Internet infrastructure, is generally regarded as an annoyance, and is said to cause a huge economic harm. Many technological, organizational, and legislative anti-spam measures have already been proposed and implemented, but have not led to any substantial decrease in the number of spam e-mails. We propose a scalable and flexible infrastructure framework that integrates several anti-spam measures and that features both a technological and an organizational facet. The key element of our infrastructure is a new organizational unit that reliably and transparently limits the number of e-mails that can be sent per day and per account. We also analyze the proposed framework in terms of its theoretical effectiveness, the required resources, and its limitations.}}, author = {{Schryen, Guido}}, keywords = {{Email, Infrastructure, Internet, Spam}}, title = {{{Preventing E-mail Spam: The Conceptualization and the Analysis of an Infrastructure Framework}}}, year = {{2007}}, } @article{5652, abstract = {{More than half of world-wide e-mail traffic ? an estimated total of several billion e-mails per day ? consists of spam. This is becoming a considerable disturbance to telecommunications. Spam is also closely related to other kinds of cyber crime as it possibly contains malicious software or is pursuing some kind of fraudulent aim, such as phishing. Besides technical and organizational measures, many countries have introduced anti-spam legislation. However, today's world-wide legislative coverage of spam is heterogeneous, and its effectiveness is controversially discussed. This article describes important parameters by which anti-spam legislation can vary and gives an overview and analysis of world-wide anti-spam legislation, including the European Directive 2002/58/EC, the U.S. CANSPAM Act of 2003, and international cooperation, such as the London Action Plan. The article then proceeds to discuss the effectiveness of current laws, and it identifies problems resulting from the fact that an international phenomenon is being addressed by national legislation. Finally, the article presents suggestions for overcoming some of these problems.}}, author = {{Schryen, Guido}}, journal = {{Information and Communications Technology Law}}, number = {{1}}, pages = {{17--32}}, publisher = {{Taylor \& Francis}}, title = {{{Anti-spam legislation: An analysis of laws and their effectiveness}}}, volume = {{16}}, year = {{2007}}, } @inproceedings{5654, abstract = {{Spamming remains a form of Internet abuse, which burdens the Internet infrastructure, is generally regarded as an annoyance, and is said to cause economic harm to the tune of about several billion US\$ per year. Many technological, organizational, and legislative anti-spam measures have already been proposed and implemented, but have not led to any substantial decrease in the number of spam e-mails. We propose here a new infrastructure framework that combines several anti-spam measures in a framework that features both a technological and an organizational facet. The key element of our infrastructure is a new organizational unit that reliably and transparently limits he number of e-mails that can be sent per day and per account. This paper first gives an overview of the framework, then it provides technological and organizational details of the infrastructure, the deployment of which depends to a large degree on its acceptance and propagation by the ICANN, the ISOC, and by large e-mail service providers. Finally, the paper discusses the limitations and drawbacks of the proposed framework.}}, author = {{Schryen, Guido}}, booktitle = {{40th Annual Hawaii International Conference on System Sciences}}, title = {{{Armed for the spam battle - a technological and organizational infrastructure framework}}}, year = {{2007}}, } @article{5655, abstract = {{Spam e-mails have become a serious technological and economic problem. Up to now, by deploying complementary anti-spam measures, we have been reasonably able to withstand spam e-mails and use the Internet for regular communication. However, if we are to avert the danger of losing the Internet e-mail service in its capacity as a valuable, free and worldwide medium of open communication, anti-spam activities should be performed more systematically than is currently the case regarding the mainly heuristic, anti-spam measures in place. A formal framework, within which the existing delivery routes that a spam e-mail may take, and anti-spam measures and their effectiveness can be investigated, will perhaps encourage a shift in methodology and pave the way for new, holistic anti-spam measures. This paper presents a model of the Internet e-mail infrastructure as a directed graph and a deterministic finite automaton and draws on automata theory to formally derive the spam delivery routes. The most important anti-spam measures are then described. Methods controlling only specific delivery routes are evaluated in terms of how effectively they cover the modeled e-mail infrastructure; methods operating independently of any particular routes receive a more general assessment.}}, author = {{Schryen, Guido}}, journal = {{The Journal of Information Systems Security (AIS Special Interest Group in Security)}}, keywords = {{e-mail, spam, e-mail infrastructure, anti-spam measures, spamming options}}, number = {{2}}, pages = {{66--90}}, title = {{{Do anti-spam measures effectively cover the e-mail communication network? A formal approach}}}, volume = {{3}}, year = {{2007}}, } @article{5658, abstract = {{Email communication is encumbered with a mass of email messages which their recipients have neither requested nor require. Even worse, the impacts of these messages are far from being simply an annoyance, as they also involve economic damage. This manuscript examines the resource ?email addresses?, which is vital for any potential bulk mailer and spammer. Both a methodology and a honeypot conceptualization for implementing an empirical analysis of the usage of email addresses placed on the Internet are proposed here. Their objective is to assess, on a quantitative basis, the extent of the current harassment and its development over time. This ?framework? is intended to be extensible to measuring the effectiveness of address-obscuring techniques. The implementation of a pilot honeypot is described, which led to key findings, some of them being: (1) Web placements attract more than two-thirds (70\%) of all honeypot spam emails, followed by newsgroup placements (28.6\%) and newsletter subscriptions (1.4\%), (2) the proportions of spam relating to the email addresses? top-level domain can be statistically assumed to be uniformly distributed, (3) More than 43\% of addresses on the web have been abused, whereas about 27\% was the case for addresses on newsgroups and only about 4\% was the case for addresses used for a newsletter subscription, (4) Regarding the development of email addresses? attractiveness for spammers over time, the service ?web sites? features a negative linear relationship, whereas the service ?Usenet? hows a negative exponential relationship. (5) Only 1.54\% of the spam emails showed an interrelation between the topic of the spam email and that of the location where the recipient?s address was placed, so that spammers are assumed to send their emails in a ?context insensitive? manner. The results of the empirical analysis motivate the need for the protection of email addresses through obscuration. We analyze this need by formulating requirements for address obscuring techniques and we reveal to which extent today?s most relevant approaches fulfill these requirements.}}, author = {{Schryen, Guido}}, journal = {{Computers & Security}}, keywords = {{Address-obfuscating techniques, email, empirical analysis, honeypot, security by design, security by obscurity, spam}}, number = {{5}}, pages = {{361--372}}, publisher = {{Elsevier}}, title = {{{The Impact that Placing Email Addresses on the Internet has on the Receipt of Spam ? An Empirical Analysis}}}, volume = {{2}}, year = {{2007}}, } @inproceedings{11720, author = {{Bevermeier, Maik and Ebel, Tobias and Haeb-Umbach, Reinhold}}, booktitle = {{Multi-Carrier Spread Spectrum 2007}}, title = {{{Channel Estimation by Exploiting Sublayer Information in OFDM Systems}}}, year = {{2007}}, } @inproceedings{11722, author = {{Bevermeier, Maik and Haeb-Umbach, Reinhold}}, booktitle = {{Multi-Carrier Spread Spectrum 2007}}, title = {{{Combined Time and Frequency Domain OFDM Channel Estimation}}}, year = {{2007}}, } @inproceedings{11785, abstract = {{In this paper we present a novel channel impulse response estimation technique for block-oriented OFDM transmission based on combining estimators: the estimates provided by a Kalman filter operating in the time domain and a Wiener filter in the frequency domain are optimally combined by taking into account their estimated error covariances. The resulting estimator turns out to be identical to the MAP estimator of correlated jointly Gaussian mean vectors. Different variants of the proposed scheme are experimentally investigated in an EEEE 802.11a-like system setup. They compare favourably with known approaches from the literature resulting in reduced mean square estimation error and bit error rate. Further, robustness and complexity issues are discussed}}, author = {{Haeb-Umbach, Reinhold and Bevermeier, Maik}}, booktitle = {{IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2007)}}, keywords = {{bit error rate, block-oriented OFDM transmission, channel estimation, channel impulse response estimation, combining estimators, error statistics, frequency domain estimation, Gaussian mean vectors, Gaussian processes, Kalman filter, Kalman filters, MAP estimator, maximum likelihood estimation, OFDM channel estimation, OFDM modulation, time domain estimation, time-frequency analysis, Wiener filter, Wiener filters}}, pages = {{III--277--III--280}}, title = {{{OFDM Channel Estimation Based on Combined Estimation in Time and Frequency Domain}}}, doi = {{10.1109/ICASSP.2007.366526}}, volume = {{3}}, year = {{2007}}, } @article{11799, abstract = {{In this paper, we propose a novel similarity measure to be used for localizing mobile terminals by comparing measured signal power levels with a database of predictions. The proposed measure provides the possibility to incorporate inherent information about signal power level measurements requested by the serving base station but not reported by the mobile terminal. Increased positioning accuracy was observed both in simulations and with real field data}}, author = {{Haeb-Umbach, Reinhold and Peschke, Sven}}, journal = {{IEEE Transactions on Vehicular Technology}}, keywords = {{cellular phone positioning, cellular radio, measured signal power levels, mobile handsets, mobility management (mobile radio)}}, number = {{1}}, pages = {{368--372}}, title = {{{A Novel Similarity Measure for Positioning Cellular Phones by a Comparison With a Database of Signal Power Levels}}}, doi = {{10.1109/TVT.2006.889563}}, volume = {{56}}, year = {{2007}}, } @inproceedings{11822, author = {{Ion, Valentin and Haeb-Umbach, Reinhold}}, booktitle = {{Interspeech 2007}}, title = {{{Multi-Resolution Soft Features for Channel-Robust Distributed Speech Recognition}}}, year = {{2007}}, } @inproceedings{11883, abstract = {{In this paper, we experimentally evaluate algorithms for velocity estimation of a GSM 900 mobile terminal which are based on the analysis of the statistical properties of the fast fading process. It is shown how theses statistics can be obtained from the training sequences present in downlink transmission bursts without establishing an active connection. Realistic simulations of a GSM channel according to the COST 207 channel models have been conducted. These models incorporate effects like multipath propagation, fading, cochannel interference and additive noise. It is shown that velocity estimation by searching for the maximum slope of the power density spectrum of the fast fading performs best.}}, author = {{Peschke, Sven and Haeb-Umbach, Reinhold}}, booktitle = {{4th Workshop on Positioning Navigation and Communication (WPNC 2007)}}, keywords = {{additive noise, cellular radio, channel estimation, cochannel interference, COST 207 channel models, downlink transmission bursts, fading channels, fading process, GSM downlink signalling, mobile terminals, multipath channels, multipath propagation, power density spectrum, statistical analysis, statistical properties, telecommunication links, telecommunication terminals, velocity estimation}}, pages = {{217--222}}, title = {{{Velocity Estimation of Mobile Terminals by Exploiting GSM Downlink Signalling}}}, doi = {{10.1109/WPNC.2007.353637}}, year = {{2007}}, } @article{11927, abstract = {{Maximizing the output signal-to-noise ratio (SNR) of a sensor array in the presence of spatially colored noise leads to a generalized eigenvalue problem. While this approach has extensively been employed in narrowband (antenna) array beamforming, it is typically not used for broadband (microphone) array beamforming due to the uncontrolled amount of speech distortion introduced by a narrowband SNR criterion. In this paper, we show how the distortion of the desired signal can be controlled by a single-channel post-filter, resulting in a performance comparable to the generalized minimum variance distortionless response beamformer, where arbitrary transfer functions relate the source and the microphones. Results are given both for directional and diffuse noise. A novel gradient ascent adaptation algorithm is presented, and its good convergence properties are experimentally revealed by comparison with alternatives from the literature. A key feature of the proposed beamformer is that it operates blindly, i.e., it neither requires knowledge about the array geometry nor an explicit estimation of the transfer functions from source to sensors or the direction-of-arrival.}}, author = {{Warsitz, Ernst and Haeb-Umbach, Reinhold}}, journal = {{IEEE Transactions on Audio, Speech, and Language Processing}}, keywords = {{acoustic signal processing, arbitrary transfer function, array signal processing, blind acoustic beamforming, direction-of-arrival, direction-of-arrival estimation, eigenvalues and eigenfunctions, generalized eigenvalue decomposition, gradient ascent adaptation algorithm, microphone arrays, microphones, narrowband array beamforming, sensor array, single-channel post-filter, spatially colored noise, transfer functions}}, number = {{5}}, pages = {{1529--1539}}, title = {{{Blind Acoustic Beamforming Based on Generalized Eigenvalue Decomposition}}}, doi = {{10.1109/TASL.2007.898454}}, volume = {{15}}, year = {{2007}}, } @inproceedings{11934, author = {{Warsitz, Ernst and Haeb-Umbach, Reinhold and Tran Vu, Dang Hai}}, booktitle = {{Interspeech 2007}}, title = {{{Blind Adaptive Principal Eigenvector Beamforming for Acoustical Source Separation}}}, year = {{2007}}, } @inproceedings{11941, author = {{Windmann, Stefan and Haeb-Umbach, Reinhold}}, booktitle = {{Interspeech 2007}}, title = {{{An Approach to Iterative Speech Feature Enhancement and Recognition}}}, year = {{2007}}, } @misc{34780, author = {{Süßmann, Johannes}}, booktitle = {{sehepunkte}}, keywords = {{Karl V., Historiographiegeschichte, Gedenken}}, number = {{4}}, title = {{{[Rez. v.] C. Scott Dixon/Martina Fuchs (Hg.): The Histories of Emperor Charles V [...]. Münster. Aschendorff 2005}}}, volume = {{7}}, year = {{2007}}, }