Foundations for Uniform Interpolation and Forgetting in Expressive Description Logics

We study uniform interpolation and forgetting in the description logic ALC. Our main results are model-theoretic characterizations of uniform inter- polants and their existence in terms of bisimula- tions, tight complexity bounds for deciding the existence of uniform interpolants, an approach to computing interpolants when they exist, and tight bounds on their size. We use a mix of model- theoretic and automata-theoretic methods that, as a by-product, also provides characterizations of and decision procedures for conservative extensions

On the Runtime of Randomized Local Search and Simple Evolutionary Algorithms for Dynamic Makespan Scheduling

Evolutionary algorithms have been frequently used for dynamic optimization problems. With this paper, we contribute to the theoretical understanding of this research area. We present the first computational complexity analysis of evolutionary algorithms for a dynamic variant of a classical combinatorial optimization problem, namely makespan scheduling. We study the model of a strong adversary which is allowed to change one job at regular intervals. Furthermore, we investigate the setting of random changes. Our results show that randomized local search and a simple evolutionary algorithm are very effective in dynamically tracking changes made to the problem instance.Comment: Conference version appears at IJCAI 201

Asset price booms and monetary policy

The paper aims at deriving some stylised facts for financial, real, and monetary policy developments during asset price booms by means of aggregating information contained in 38 boom periods since the 1970s for 18 OECD countries. We observe 26 macroeconomic variables in a pre-boom, boom and post-boom phase. Not all booms lead to large output losses. We divide our sample in high-cost and low-cost booms and analyse the differences. High-cost booms are clearly those in which real estate prices and investment crash in the post-boom periods. In general it is difficult to distinguish a highcost from a low-cost boom at an early stage. However, high-cost booms seem to follow very rapid growth in the real money and real credit stocks just before the boom and at the early stages of a boom. During high-cost booms, rates of change of real estate prices and consumption growth are significantly higher and the investment (especially housing) GDP ratio deviation from trend rises faster over the whole boom period. There is also evidence that high-cost booms are associated with significantly looser monetary policy conditions over the boom period, especially towards the late stage of a boom. We finally discuss the results with regard to the theoretical literature. The looser monetary policy at the later stage of high-cost booms could be interpreted in different ways. It could be that excessively loose monetary policy contributes to extending the boom and exacerbating the real and financial imbalances. Alternatively, observed monetary policy could reflect a desirable, pre-emptive loosening in anticipation of an asset price crash to come. JEL Classification: E44, E52, E58and monetary policy developments, real, The paper aims at deriving some stylised facts for financial

Stand-off Detection at the DLR Laser Test Range Applying Laser-Induced Breakdown Spectroscopy

The DLR laser test range at Lampoldshausen allows for optical measurements under daylight conditions at distances up to 130 m. This infrastructure is very suitable for the development of stand-off detection systems of biological, chemical and explosive hazardous substances. In a first step, laser-induced breakdown spectroscopy (LIBS) has been introduced to this test site. A basic LIBS set-up and first LIBS spectra of selected samples are presented. A Nd:YAG laser beam was focussed by a Cassegrain type telescope onto different samples at distances exceeding 50 m. The light of the generated plasma plume was collected by a Newtonian telescope, and analyzed by a gated broadband CCD-spectrometer system. The Nd:YAG laser yields pulse energies up to 800 mJ at a wavelength of 1064 nm and a pulse width of 8 ns. Optionally the second and third harmonics can be extracted. LIBS spectra from 10 nm layers of gold on a silicon wafer were recorded. In addition, LIBS spectra from black powder were measured, and compared to the spectrum of potassium nitrate, which is a main component of black powder and shows very characteristic emission. LIBS spectra of the above samples have also been acquired with an excitation laser wavelength in the eye-safe region. Recorded spectra are measured as a function of the laser wavelength, pulse energy, and energy density on the target and are compared to the literature

Evidence for Non-Random Hydrophobicity Structures in Protein Chains

The question of whether proteins originate from random sequences of amino acids is addressed. A statistical analysis is performed in terms of blocked and random walk values formed by binary hydrophobic assignments of the amino acids along the protein chains. Theoretical expectations of these variables from random distributions of hydrophobicities are compared with those obtained from functional proteins. The results, which are based upon proteins in the SWISS-PROT data base, convincingly show that the amino acid sequences in proteins differ from what is expected from random sequences in a statistical significant way. By performing Fourier transforms on the random walks one obtains additional evidence for non-randomness of the distributions. We have also analyzed results from a synthetic model containing only two amino-acid types, hydrophobic and hydrophilic. With reasonable criteria on good folding properties in terms of thermodynamical and kinetic behavior, sequences that fold well are isolated. Performing the same statistical analysis on the sequences that fold well indicates similar deviations from randomness as for the functional proteins. The deviations from randomness can be interpreted as originating from anticorrelations in terms of an Ising spin model for the hydrophobicities. Our results, which differ from previous investigations using other methods, might have impact on how permissive with respect to sequence specificity the protein folding process is -- only sequences with non-random hydrophobicity distributions fold well. Other distributions give rise to energy landscapes with poor folding properties and hence did not survive the evolution.Comment: 16 pages, 8 Postscript figures. Minor changes, references adde

Local Interactions and Protein Folding: A 3D Off-Lattice Approach

The thermodynamic behavior of a three-dimensional off-lattice model for protein folding is probed. The model has only two types of residues, hydrophobic and hydrophilic. In absence of local interactions, native structure formation does not occur for the temperatures considered. By including sequence independent local interactions, which qualitatively reproduce local properties of functional proteins, the dominance of a native state for many sequences is observed. As in lattice model approaches, folding takes place by gradual compactification, followed by a sequence dependent folding transition. Our results differ from lattice approaches in that bimodal energy distributions are not observed and that high folding temperatures are accompanied by relatively low temperatures for the peak of the specific heat. Also, in contrast to earlier studies using lattice models, our results convincingly demonstrate that one does not need more than two types of residues to generate sequences with good thermodynamic folding properties in three dimensions.Comment: 18 pages, 11 Postscript figure

Prediction of dynamic pairwise wake vortex separations for approach and landing

Design and performance of the Wake Vortex Prediction and Monitoring System WSVBS are described. The WSVBS has been developed to tactically increase airport capacity for approach and landing on single runways as well as closely-spaced parallel runways. It is thought to dynamically adjust aircraft separations dependent on weather conditions and the resulting wake vortex behavior without compro-mis>ing safety. Dedicated meteorological instrumentation and short-term numerical terminal weather prediction provide the input to the prediction of wake-vortex behavior and respective safety areas. LIDAR monitors the correctness of WSVBS predictions in the most critical gates at low altitude. The WSVBS is integrated in the arrival manager AMAN of DLR. Performance tests of the WSVBS have been accomplished at Frankfurt airport in winter 2006/07 and at Munich Airport in summer 2010. Aircraft separations for landings on single runways have been compared employing the concepts of either heavy-medium weight class combinations or dynamic pairwise separations where individual aircraft type pairings are considered. For the very conservative baseline setup of the WSVBS the potential capacity gains of dynamic pairwise operations for single runways appear to be very small. On the other hand, the consideration of individual aircraft types and their respective wake characteristics may almost double the fraction of time when radar separation could be applied

Polyphasische Taxonomie, Kerngenom und Lebenszyklus von Rhodopirellula-Stämmen

This thesis focused on three major projects dealing with the planctomycetes of the species Rhodopirellula baltica. In a polyphasic taxonomic study the morphological, physiological and chemotaxonomic characteristics of 17 newly isolated strains were investigated. Based on the obtained results and phylogenetic data ten new Rhodopirellula species were introduced along with one new genus. The physiology of the strains was studied with regard to the influence of ammonium on their life style. Using flow cytometry an increase of aggregated cells compared to single cells was observed parallel to an increase of the ammonium concentration. In chemostat cultures an ammonium shock induced the formation of a R. baltica biofilm by attachment of cells to the fermenter wall. With ten strains the Rhodopirellula core genome was determined by microarray analysis and genome sequencing. Both methods were compared. The R. baltica core genome contains 3314 shared genes according to microarray analysis and 4232 shared genes according to genome annotation. The investigations of this work are the basis for future comparative studies between Rhodopirellula species

Survivability : A Unifiying Concept for the Transient Resilience of Deterministic Dynamical Systems

16 pagesNon peer reviewedPreprin