2,150 Works

A genome-wide study of two-component signal transduction systems in eight newly sequenced mutans streptococci strains

Lifu Song, Padhmanand Sudhakar, Wei Wang, Georg Conrads, Anke Brock, Jibin Sun, Irene Wagner-Döbler & An-Ping Zeng
Mutans streptococci are a group of gram-positive bacteria including the primary cariogenic dental pathogen Streptococcus mutans and closely related species. Two component systems (TCSs) composed of a signal sensing histidine kinase (HK) and a response regulator (RR) play key roles in pathogenicity, but have not been comparatively studied for these oral bacterial pathogens.

A logic-based approach to multimedia interpretation

Atila Kaya
In this thesis, we present a novel approach for the automatic generation of rich semantic metadata based on surface-level information. For the extraction of the required surface-level information, state-of-the-art analysis tools are used. The approach exploits a logic-based formalism as the foundation for knowledge representation and reasoning. To develop a declarative approach, we formalize a multimedia interpretation algorithm that exploits formal inference services offered by a state-of-the-art reasoner. Furthermore, we present the semantic interpretation engine,...

Combined FEM-SPH simulations for ice in compression

Niklas Düchting
Within this chapter the outcome of the numerical investigation on a combined FEM-SPH simulation is summed up. The practical approach of this project allows only a rather sim-ple assessment and there are aspects that need to be investigated further. An outlook in-dicates possible aspects for future research. Regarding the correlation of the contact forces the results of the final simulations pre-sented in section 3.3.1 are satisfying. The ability to model the transformation of the ma-terial...

Inteins, valuable genetic elements in molecular biology and biotechnology

Skander Elleuche & Stefanie Pöggeler
Inteins are internal protein elements that self-excise from their host protein and catalyze ligation of the flanking sequences (exteins) with a peptide bond. They are found in organisms in all three domains of life, and in viral proteins. Intein excision is a posttranslational process that does not require auxiliary enzymes or cofactors. This self-excision process is called protein splicing, by analogy to the splicing of RNA introns from pre-mRNA. Protein splicing involves only four intramolecular...

Windkanalversuche für einen sechsmastigen Segler nach Prölss

Bernd Wagner
Windkanalversuche für einen sechsmastigen Segler nach Prölss

Electrochemical tuning of the optical properties of nanoporous gold

Dirk Jalas, Li-Hua Shao, Rashmi Canchi, Toshiya Okuma, Slawa Lang, Alexander Petrov, Jörg Weißmüller & Manfred Eich
Using optical in-situ measurements in an electrochemical environment, we study the electrochemical tuning of the transmission spectrum of films from the nanoporous gold (NPG) based optical metamaterial, including the effect of the ligament size. The long wavelength part of the transmission spectrum around 800 nm can be reversibly tuned via the applied electrode potential. The NPG behaves as diluted metal with its transition from dielectric to metallic response shifted to longer wavelengths. We find that the...

Evaluation of the unsteady propeller performance behind ships in waves

Katja Wöckner-Kluwe
In the present work a close and unsteady coupling procedure between a RANS-method and a potential-flow method is developed. The work is motivated by the large computational effort for unsteady viscous-flow simulations using geometrically resolved propellers. By combining the two methods for the simulation of the operating propeller in the ship's wake, the analysis of the dynamics of ships and operating propellers in seaways becomes possible. Inside the coupling the RANS-method is used to compute...

Rissbildung in fugenlosen Kaianlagen - ein Berechnungsmodell für massige Bauteile aus Stahlbeton

Jens Wasner
The thesis contributes to the determination of the effective restraint action in large jointless quays. The focus is on the particular cracking behaviour of the voluminous reinforced concrete superstructures. For this purpose special mechanical models are developed. With those the non-linear material behaviour and bond relation are mapped to reality. After an introduction about the development of container shipping different types of quays with jointless superstructure are presented. Then the material properties of concrete and...

On the direct kinematics problem of parallel mechanisms

Arthur Seibel, Stefan Schulz & Josef Schlattmann
The direct kinematics problem of parallel mechanisms, that is, determining the pose of the manipulator platform from the linear actuators’ lengths, is, in general, uniquely not solvable. For this reason, instead of measuring the lengths of the linear actuators, we propose measuring their orientations and, in most cases, also the orientation of the manipulator platform. This allows the design of a low-cost sensor system for parallel mechanisms that completely renounces length measurements and provides a...

Design for X : Beiträge zum 23. DfX-Symposium Oktober 2012

Dieter Krause, Kristin Paetzold & Sandro Wartzack
Das Symposium Design for X findet nun bereits zum 23. Mal statt, in diesem Jahr inmitten der wunderschönen Altstadt Bambergs. Der Austragungsort wechselt, der Geist des Symposiums bleibt: Auch in diesem Jahr stehen Doktoranden, die Ihre Forschungsprojekte vorstellen und diskutieren möchten im Vordergrund. Ergänzt werden diese durch vier Keynote-Vorträge, hauptsächlich von Industrievertretern, die in Plenarvorträgen über den entsprechenden Stand und aktuelle Herausforderungen in der Produktentwicklung berichten. Ich freue mich sehr, dass gerade in diesem Jahr...

Elastic and plastic poisson’s ratios of nanoporous gold

Lukas Lührs, Celal Soyarslan, Jürgen Markmann, Swantje Bargmann & Jörg Weißmüller
We explore the elastic and plastic Poisson’s ratios, mE and mP, of nanoporous gold, using digital image correlation during compression experiments including load/unload segments. The two coefficients differ significantly, with mE independent of the ligament size, L, and with a trend for mP / L at not too large L. Disorder in the network of ligaments may explain why mE is smaller than predicted by lattice-based models. Finite element simulations, based on the Deshpande–Fleck constitutive...

RUVIVAL Publication Series Volume 3

Joachim Behrendt, Dario Fröndhoff, Andrea Munoz Ardila, Maria Monina Orlina, Máryeluz Rueda Morales & Ruth Schaldach
RUVIVAL Publication Series is a compilation of literature reviews on topics concerned with the revitalisation of rural areas. RUVIVAL Publication Series is part of the e-learning project RUVIVAL and each of the three contributions in this publication is connected to further interactive multimedia material, which can be reached under www.ruvival.de. The first literature review is concerned with urine utilisation as a fertiliser in agriculture. Urine contains four important nutrients for plant growth: nitrogen (N), phosphorus...

Die hydrodynamischen Größen bei der Roll- und Querbewegung eines Küstenmotorschiffes auf tiefem Wasser

Harald Keil
Die hydrodynamischen Größen bei der Roll- und Querbewegung eines Küstenmotorschiffes auf tiefem Wasser

Gypsum scaling during reverse osmosis desalination − characterization and effects of natural organic matter

Jan Benecke
Desalination of brackish and salty water by reverse osmosis (RO) has been increasingly applied to address regional water shortages. Especially at high water recovery, the crystallization of sparingly soluble salts near or on the membrane surface (‘scaling’) is a serious limitation during RO operation. This dissertation characterizes scaling by gypsum (CaSO4∙2H2O) and its interactions with natural organic matter (NOM) in cross-flow RO and stirred beaker crystallization experiments. The results show that gypsum scaling and associated...

Kombinatorisches und Kreatives zum Verhältnis von Mathematik und Bibliothek

Thomas Hapke
Ausgehend von einer Aussage des Chemikers Wilhelm Ostwald zur Kombinatorik als Komponente von Kreativität wird in diesem Essay durch Zitate aus der "Bibliothek von Babel" von Jorge Luis Borges der Zusammenhang zwischen Bibliothek und Kombinatorik und damit Mathematik illustriert. Abschliessend wird das Verhältnis von Kombinatorik und Kreativität im Rahmen von modernen Ideen eines alternativen Umgangs mit dem Urheberrecht (Creative Commons) thematisiert: Die "Bibliothek von Babel", die alle Werke enthält, die aus der Kombination von allen...

The implementation of performance-oriented systems

Tim Schiederig
The study at hand examines the strategic perspective of the emerging phenomenon of performance-oriented systems, e.g. car-sharing or cloud computing, in the mobility, IT, energy and chemical industries. In all four industries, firms have likewise implemented a novel system-based offering recently, which is providing the performance of their products for shared use. The existing literature that has already acknowledged the phenomenon is fragmented across different areas of expertise. The emphasis of the contributions resides on...

Potentialtheoretische Berechnungen des Strömungsfeldes eines Deltaflügels mit Hilfe von Elementarwirbeln

Christian Heckel
Potentialtheoretische Berechnungen des Strömungsfeldes eines Deltaflügels mit Hilfe von Elementarwirbeln Für die Berechnung von Strömungsfeldern und den hierdurch induzierten Druck-verteilungen hat sich in vielen Fällen die Anwendung der Potentialtheorie bewährt. Ins besondere zeigt sich bei Flügelprofilen, auch unter Berücksichtigung von Kavitationserscheinungen, eine sehr gute Übereinstimmung von Theorie und Messung. Die Eignung der Potentialtheorie motivierte daher ihre Anwendung auf die Berechnung des Strömungsfeldes eines Deltaflügels. Experimentelle Untersuchungen dieses Flügeltyps weisen für Profile mit kleinem Seitenverhältnis typische...

Nanofiltration for safe drinking water in underdeveloped regions – a feasibility study

Sreenivasan Ramaswami, Zafar Navid Ahmad, Maximilian Slesina, Joachim Behrendt & Ralf Otterpohl
The fact from the United Nations that in 2015, about 663 million people worldwide did not have access to an improved drinking water source, does not resemble the reality wherein more than 1.8 billion people worldwide were consuming water which is unsafe for drinking. Nanofiltration, with the ability to reject several trace organic compounds, heavy metals and viruses at a lower energy demand than reverse osmosis, has found application for the production of high quality...

Stadthygiene und Abwasserreinigung nach der Hamburger Cholera-Epidemie : Umweltforschung vor 100 Jahren im Spiegel der Bibliothek der Sielklär-Versuchsstation Hamburg-Eppendorf

Dirk Schubert, Martin Oldenburg & Thomas Hapke
[Ausstellung in der Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 19. Juli 1993 bis 25. September 1993] Die "Bibliothek der Sielklär-Versuchsstation Hamburg-Eppendorf", eine ca. 450 Bände umfassende Spezialbibliothek zur Wasser- und Abwasserforschung um die Jahrhundertwende, ist durch eine Schenkung 1984 an die Universitätsbibliothek der Technischen Universität Hamburg-Harburg gekommen. Im Bestand dieser Bibliothek und damit auch in dieser Ausstellung spiegelt sich die Umwelt- und Abwasserforschung Ende des 19. Jahrhunderts wider. Bibliotheks- und buchgeschichtlich interessant ist dabei nicht, daß...

Bulk nested-network nanoporous gold via dealloying

Zhen Qi
A two-step dealloying strategy has been established via controlled dealloying to fabricate hierarchical nanoporous gold which has two well distinguished levels of ligaments from a bulk solid. Starting out from a dilute solid solution of Au in Ag, controlled electrochemical corrosion yields nanoporous Ag-Au alloy as an intermediate product. Coarsening of the porous alloy creates the large ligaments of the upper hierarchy level. Those are then again dealloyed, which creates the fine ligaments of the...

A novel cyclodextrin glycosyltransferase from alkaliphilic amphibacillus sp. NPST-10 : purification and properties

Abdelnasser S. S. Ibrahim, Ali A. Al-Salamah, Mohamed A. El-Tayeb, Yahya B. Elbadawi & Garabed Antranikian
Screening for cyclodextrin glycosyltransferase (CGTase)-producing alkaliphilic bacteria from samples collected from hyper saline soda lakes (Wadi Natrun Valley, Egypt), resulted in isolation of potent CGTase producing alkaliphilic bacterium, termed NPST-10. 16S rDNA sequence analysis identified the isolate as Amphibacillus sp. CGTase was purified to homogeneity up to 22.1 fold by starch adsorption and anion exchange chromatography with a yield of 44.7%. The purified enzyme was a monomeric protein with an estimated molecular weight of 92...

Ein Oszillator zur Ermittlung hydrodynamischer Massen und Dämpfungswerte

Harald Keil & Hans Thiemann
Ein Oszillator zur Ermittlung hydrodynamischer Massen und Dämpfungswerte

A symmetry exploiting Lanczos method for symmetric Toeplitz matrices

Heinrich Voß
Several methods for computing the smallest eigenvalues of a symmetric and positive definite Toeplitz matrix T have been studied in the literature. The most of them share the disadvantage that they do not reflect symmetry properties of the corresponding eigenvector. In this note we present a Lanczos method which approximates simultaneously the odd and the even spectrum of T at the same cost as the classical Lanczos approach.

Die Erzeugung von Rotationskörpern aus vorgegebenen Singularitätenverteilungen

Maria Kirsch
Die Erzeugung von Rotationskörpern aus vorgegebenen Singularitätenverteilungen

Computability Theory

Karl-Heinz Zimmermann
This book is a development of class notes for a two-hour lecture including a two-hour lab held for second-year Bachelor students of Computer Science at the Hamburg University of Technology during the last few years. The course aims to present the basic results of computability theory, including well-known mathematical models of computability such as the Turing machine, the unlimited register machine (URM), and GOTO and LOOP programs, the principal classes of computational functions like the...

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