10,167 Works

Vibrational-state and isotope dependence of high-order harmonic generation in water molecules

Mirjam Falge, Volker Engel & Manfred Lein
We report calculations on high-order harmonic generation in water molecules. Spectra are determined for various initial vibrational states of H2O and its isotope D2O. It is demonstrated that the ratio of the spectra for D2O and H2O is close to unity when the initial state is the vibronic ground state, indicating that nuclear dynamics is of minor importance. For vibrationally excited initial states, the high-harmonic intensities show a clear dependence on both the initial-state quantum...

Two-center interference and ellipticity in high-order harmonic generation from H2+

Elmar V. Van Der Zwan & Manfred Lein
We present a theoretical investigation into the two-center interference in aligned H2+. The influence of the laser field on the recombination step is investigated by comparing laser-induced harmonic generation with harmonic generation from field-free collisions of Gaussian wave packets with the core. We find that for different Gaussian wave packets colliding with the molecule, the interference minimum occurs at the same alignment angle. The same result is obtained for the laser-induced spectrum when only a...

Photoelectron circular dichroism of chiral molecules studied with a continuum-state-corrected strong-field approximation

Ingo Dreissigacker & Manfred Lein
Motivated by recent experiments on circular dichroism in the photoelectron momentum distributions from strong-field ionization of chiral molecules [C. Lux, Angew. Chem. Int. Ed. 51, 5001 (2012)1433-785110.1002/anie.201109035; C. S. Lehmann, J. Chem. Phys. 139, 234307 (2013)JCPSA60021-960610.1063/1.4844295], we investigate the origin of this effect theoretically. We show that it is not possible to describe photoelectron circular dichroism with the commonly used strong-field approximation due to its plane-wave nature. We therefore apply the Born approximation to the...

Signatures of Molecular Orbital Structure in Lateral Electron Momentum Distributions from Strong-Field Ionization

Ingo Petersen, Jost Henkel & Manfred Lein
Strong-field ionization of aligned diatomic and polyatomic molecules such as O2, N2, C2H4, and others in circularly polarized laser fields is investigated theoretically. By calculating the emission-angle-resolved lateral width of the momentum distribution perpendicular to the polarization plane, we show that nodal planes in molecular orbitals are directly imprinted on the angular dependence of the width. We demonstrate that orbital symmetries can be distinguished with the information obtained by observing the lateral width in addition...

Adiabaticity in the lateral electron-momentum distribution after strong-field ionization

Jost Henkel, Manfred Lein, Volker Engel & Ingo Dreissigacker
By solving the time-dependent Schrödinger equation for atoms in short laser pulses of different polarizations, it is shown that in strong-field ionization without rescattering, the lateral width of the electron-momentum distribution corresponds adiabatically to the instantaneous laser field on a sub-laser-cycle time scale, as expected in pure tunneling ionization. In contrast to the distributions along the polarization direction, the width is affected little by depletion or Coulomb effects. © 2012 American Physical Society.

Semiclassical two-step model for strong-field ionization

N.I. Shvetsov-Shilovski, Manfred Lein, L.B. Madsen, E. Räsänen, C. Lemell, J. Burgdörfer, D.G. Arbó & K. Tokési
We present a semiclassical two-step model for strong-field ionization that accounts for path interferences of tunnel-ionized electrons in the ionic potential beyond perturbation theory. Within the framework of a classical trajectory Monte Carlo representation of the phase-space dynamics, the model employs the semiclassical approximation to the phase of the full quantum propagator in the exit channel. By comparison with the exact numerical solution of the time-dependent Schrödinger equation for strong-field ionization of hydrogen, we show...

Determination of ionization and tunneling times in high-order harmonic generation

Jing Zhao & Manfred Lein
From the numerical solution of the time-dependent Schrödinger equation, we obtain the times of ionization and return of the laser-driven electron in high-order harmonic generation by probing the dynamics with a second harmonic field polarized orthogonal to the fundamental field and observing the harmonic emission in dependence on the two-color delay. Our retrieval method using complex-time evolution gives ionization and return times in excellent agreement with the quantum-orbit model, while a retrieval based on real-time...

Eine Schule für alle! : Grundlagen und Leitlinien für eine gelingende Umsetzung von Inklusion am Beispiel ausgewählter Schulen

Julia Schulze
Die Vision der Inklusion und der damit verbundenen Etablierung einer Schule für alle kann als ein globales Phänomen bezeichnet werden (vgl. Löser & Werning, 2015, S. 18). Durch eine Ratifizierung der UN-Behindertenrechtskonvention im Jahr 2008 haben sich viele Länder und insbesondere auch Deutschland zur Gewährleistung eines inklusiven Schulsystems verpflichtet. „Die Einführung inklusiver Bildungssysteme, die den Bedürfnissen aller Lernenden gerecht werden, stellt [dabei] weltweit eine zentrale Aufgabe der Bildungspolitik wie auch der Praxis von Schulen dar“...

Expert*innen für die Räume dieser Welt?! : Eine empirische Untersuchung zur Professionalität von Erdkundelehrkräften im Umgang mit Raummodulen am Beispiel von Australien und Ozeanien

Julia Althoff
This paper discusses the geography curriculum for grammar schools in Lower Saxony (Germany) in the 12th and 13th grade. The curriculum does not only prescribe thematic modules (‘Fachmodule’) but also alternating regional modules (‘Raummodule’). The latter ones are defined with reference to a concept subdividing the world into ‘cultural continents’ from the 1960s (‘Kulturerdteilkonzept’). Even though geography teachers in Lower Saxony may choose either the thematic modules or the regional modules as the superordinate structure...

Crack propagation in rubber blends : impact of blend morphology and energy dissipation mechanisms around the crack tip

Matthias Wunde
This works deals with crack growth investigations of tire tread compounds in laboratory. These measurements are usually performed with the Tear Fatigue Analyzer. In the Tear Fatigue Analyzer notched strip samples are loaded dynamically and the resulting crack growth rate dc/dn is measured. This way the crack growth rate dc/dn in dependence of tearing energy T can be determined for a compound under specific loading condition. The tearing energy T describes the energy available for...

Assessing the Application Potential of Selected Ecosystem-Based, Low-Regret Coastal Protection Measures

C. Gabriel David, Nannina Schulz & Torsten Schlurmann
Climate change and subsequent processes triggered by climate change demand novel assessments and protection schemes in coastal environments, as frequency and intensity of extreme events as well as mean sea water levels are expected to rise. Most often, conventional coastal engineering approaches are solely built for protection purposes, but often come with negative side-effects to the coastal environment and communities. During the last decade, new concepts in coastal engineering have started emerging. Several technical measures...

Vision-based indoor localization via a visual slam approach

M. Li & F. Rottensteiner
With an increasing interest in indoor location based services, vision-based indoor localization techniques have attracted many attentions from both academia and industry. Inspired by the development of simultaneous localization and mapping technique (SLAM), we present a visual SLAM-based approach to achieve a 6 degrees of freedom (DoF) pose in indoor environment. Firstly, the indoor scene is explored by a keyframe-based global mapping technique, which generates a database from a sequence of images covering the entire...

Supervised detection of bomb craters in historical aerial images using convolutional neural networks

D. Clermont, C. Kruse, F. Rottensteiner & C. Heipke
The aftermath of the air strikes during World War II is still present today. Numerous bombs dropped by planes did not explode, still exist in the ground and pose a considerable explosion hazard. Tracking down these duds can be tackled by detecting bomb craters. The existence of a dud can be inferred from the existence of a crater. This work proposes a method for the automatic detection of bomb craters in aerial wartime images. First...

Xenogeneic modulation of the ClpCP protease of Bacillus subtilis by a phage-encoded adaptor-like protein

N. Mulvenna, I. Hantke, L. Burchell, S. Nicod, D. Bell, K. Turgay & S. Wigneshweraraj
Like eukaryotic and archaeal viruses, which coopt the host's cellular pathways for their replication, bacteriophages have evolved strategies to alter the metabolism of their bacterial host. SPO1 bacteriophage infection of Bacillus subtilis results in comprehensive remodeling of cellular processes, leading to conversion of the bacterial cell into a factory for phage progeny production. Acluster of 26 genes in the SPO1 genome, called the host takeover module, encodes for potentially cytotoxic proteins that specifically shut down...

Apoptosis and cell cycle regulation in a basal model system : insights from the placozoan Trichoplax adhaerens

Sarah Rolfes
Complex gene networks regulated by master control genes are critical for the coordination of fundamental molecular and cellular processes in metazoans. Their misfunction might cause severe diseases like cancer. In this thesis, two evolutionary highly conserved master control genes, namely p53 and Myc, have been comprehensively analyzed in the simple metazoan model system Trichoplax adhaerens (phylum Placozoa). Additionally, the newly described species, Polyplacotoma mediterranea, will provide further promising possibilities for functional and comparative studies. The...

Nachhaltigkeitsbewertung und -bewusstsein entlang der „textilen Kette“ am Beispiel ausgewählter Unternehmen : Ein didaktisches Modell zur Vermittlung von „Transformative Literacy“ im Rahmen schulischer Bildungsprozesse und Lehrerbildungsangebote

Christiane Meyer & Christine Höbermann
DBU Abschlussbericht AZ 33711. Anlass des Vorhabens war u.a. der Bedarf an Unterrichtseinheiten, die dezidiert Nachhaltigkeitskriterien unter Berücksichtigung der Dimensionen nachhaltiger Entwicklung (Ökologie, Ökonomie, Soziales, aber auch Kultur und Politik) fokussieren und orientiert an einem ganzheitlichen Modell zur Werte-Bildung sowie den Wissensformen einer „Transformative Literacy“ zu Nachhaltigkeitsbewertung und -bewusstsein beitragen. Aufgrund der lebensweltlichen Bedeutung von Kleidung insbesondere für Jugendliche bietet sich die „textile Kette“ als Kontext mit fachlicher und ethischer Komplexität, globalen Verflechtungen und unternehmerischen...

Handheld optoacoustic probe facilitating nearfield investigations through a transparent detector

Elias Möller
Modern medicine relies strongly on measurement devices, enabling the physician to investigate the human body in ever greater detail. In addition to established techniques of optical microscopy, ultrasound, x-ray and magnetic resonance imaging, optoacoustic (OA) imaging is on its path to enter the clinics. The research field of optoacoustics already produced a variety of remarkable setups, from high resolution microscopy to deep penetrating tomography. Through the broad range of wavelengths available for this technique, it...

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species

Corinna E. Dreher, Molly E. Cummings & Heike Pröhl
Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O....

Multiple sexual signals: calls over colors for mate attraction in an aposematic, color-diverse poison frog

Corinna E. Dreher & Heike Pröhl
Sexual signals indicate species identity and mate quality, and their importance for mate attraction is largely recognized. Recently, research in animal communication has started to integrate multiple signal modalities and evaluate their interactions. However, mate choice experiments across animal taxa have been limited to laboratory conditions, and assessments of multiple sexual signals under field conditions are still lacking. We take advantage of the divergence in visual and acoustic signals among populations of the Neotropical poison...

Brassica napus L. cultivars show a broad variability in their morphology, physiology and metabolite levels in response to sulfur limitations and to pathogen attack

Annekathrin Weese, Philip Pallmann, Jutta Papenbrock & Anja Riemenschneider
Under adequate sulfur supply, plants accumulate sulfate in the vacuoles and use sulfur-containing metabolites as storage compounds. Under sulfur-limiting conditions, these pools of stored sulfur-compounds are depleted in order to balance the nitrogen to sulfur ratio for protein synthesis. Stress conditions like sulfur limitation and/or pathogen attack induce changes in the sulfate pool and the levels of sulfur-containing metabolites, which often depend on the ecotypes or cultivars. We are interested in investigating the influence of...

Salicornia as a crop plant in temperate regions: selection of genetically characterized ecotypes and optimization of their cultivation conditions

Devesh Singh, Anne K. Buhmann, Tim J. Flowers, Charlotte E. Seal & Jutta Papenbrock
Rising sea levels and salinization of groundwater due to global climate change result in fast-dwindling sources of freshwater. Therefore, it is important to find alternatives to grow food crops and vegetables. Halophytes are naturally evolved salt-tolerant plants that are adapted to grow in environments that inhibit the growth of most glycophytic crop plants substantially. Members of the Salicornioideae are promising candidates for saline agriculture due to their high tolerance to salinity. Our aim was to...

The alternative Medicago truncatula defense proteome of ROS - defective transgenic roots during early microbial infection

Leonard Muriithi Kiirika, Udo Schmitz & Frank Colditz
ROP-type GTPases of plants function as molecular switches within elementary signal transduction pathways such as the regulation of ROS synthesis via activation of NADPH oxidases (RBOH-respiratory burst oxidase homolog in plants). Previously, we reported that silencing of the Medicago truncatula GTPase MtROP9 led to reduced ROS production and suppressed induction of ROS-related enzymes in transgenic roots (MtROP9i) infected with pathogenic (Aphanomyces euteiches) and symbiotic microorganisms (Glomus intraradices, Sinorhizobium meliloti). While fungal infections were enhanced, S....

Integrated GNSS Attitude Determination and Positioning for Direct Geo-Referencing

Nandakumaran Nadarajah, Jens-André Paffenholz & Peter J.G. Teunissen
Direct geo-referencing is an efficient methodology for the fast acquisition of 3D spatial data. It requires the fusion of spatial data acquisition sensors with navigation sensors, such as Global Navigation Satellite System (GNSS) receivers. In this contribution, we consider an integrated GNSS navigation system to provide estimates of the position and attitude (orientation) of a 3D laser scanner. The proposed multi-sensor system (MSS) consists of multiple GNSS antennas rigidly mounted on the frame of a...

Storage and transformation of organic matter fractions in cryoturbated permafrost soils across the Siberian Arctic

Norman Gentsch, Robert Mikutta, Ricardo J. Eloy Alves, Jin Barta, Petr Čapek, Antje Gittel, Gustaf Hugelius, Peter Kuhry, Nikolay Lashchinskiy, Juri Palmtag, Andreas Richter, Hana Šantrůčková, Jörg Schnecker, Olga Shibistova, Tim Urich, B. Wild & Georg Guggenberger
In permafrost soils, the temperature regime and the resulting cryogenic processes are important determinants of the storage of organic carbon (OC) and its small-scale spatial variability. For cryoturbated soils, there is a lack of research assessing pedon-scale heterogeneity in OC stocks and the transformation of functionally different organic matter (OM) fractions, such as particulate and mineral-associated OM. Therefore, pedons of 28 Turbels were sampled in 5 m wide soil trenches across the Siberian Arctic to...

Cochlear Dummy Electrodes for Insertion Training and Research Purposes: Fabrication, Mechanical Characterization, and Experimental Validation

Jan-Philipp Kobler, Anandhan Dhanasingh, Raphael Kiran, Claude Jolly & Tobias Ortmaier
To develop skills sufficient for hearing preservation cochlear implant surgery, surgeons need to performseveral electrode insertion trials in ex vivo temporal bones, thereby consuming relatively expensive electrode carriers. The objectives of this study were to evaluate the insertion characteristics of cochlear electrodes in a plastic scala tympani model and to fabricate radio opaque polymer filament dummy electrodes of equivalent mechanical properties. In addition, this study should aid the design and development of new cochlear electrodes....

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