TY - CHAP A1 - Abdennadher, Slim A1 - Ismail, Haythem A1 - Khoury, Frederick T1 - Transforming imperative algorithms to constraint handling rules N2 - Different properties of programs, implemented in Constraint Handling Rules (CHR), have already been investigated. Proving these properties in CHR is fairly simpler than proving them in any type of imperative programming language, which triggered the proposal of a methodology to map imperative programs into equivalent CHR. The equivalence of both programs implies that if a property is satisfied for one, then it is satisfied for the other. The mapping methodology could be put to other beneficial uses. One such use is the automatic generation of global constraints, at an attempt to demonstrate the benefits of having a rule-based implementation for constraint solvers. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41533 ER - TY - THES A1 - Adelhelm, Philipp T1 - Novel carbon materials with hierarchical porosity : templating strategies and advanced characterization T1 - Neue Kohlenstoffmaterialien mit hierarchischer Porosität : Strategien der Templatierung und erweiterte Charakterisierung N2 - The aim of this work was the generation of carbon materials with high surface area, exhibiting a hierarchical pore system in the macro- and mesorange. Such a pore system facilitates the transport through the material and enhances the interaction with the carbon matrix (macropores are pores with diameters > 50 nm, mesopores between 2 – 50 nm). Thereto, new strategies for the synthesis of novel carbon materials with designed porosity were developed that are in particular useful for the storage of energy. Besides the porosity, it is the graphene structure itself that determines the properties of a carbon material. Non-graphitic carbon materials usually exhibit a quite large degree of disorder with many defects in the graphene structure, and thus exhibit inherent microporosity (d < 2nm). These pores are traps and oppose reversible interaction with the carbon matrix. Furthermore they reduce the stability and conductivity of the carbon material, which was undesired for the proposed applications. As one part of this work, the graphene structures of different non-graphitic carbon materials were studied in detail using a novel wide-angle x-ray scattering model that allowed precise information about the nature of the carbon building units (graphene stacks). Different carbon precursors were evaluated regarding their potential use for the synthesis shown in this work, whereas mesophase pitch proved to be advantageous when a less disordered carbon microstructure is desired. By using mesophase pitch as carbon precursor, two templating strategies were developed using the nanocasting approach. The synthesized (monolithic) materials combined for the first time the advantages of a hierarchical interconnected pore system in the macro- and mesorange with the advantages of mesophase pitch as carbon precursor. In the first case, hierarchical macro- / mesoporous carbon monoliths were synthesized by replication of hard (silica) templates. Thus, a suitable synthesis procedure was developed that allowed the infiltration of the template with the hardly soluble carbon precursor. In the second case, hierarchical macro- / mesoporous carbon materials were synthesized by a novel soft-templating technique, taking advantage of the phase separation (spinodal decomposition) between mesophase pitch and polystyrene. The synthesis also allowed the generation of monolithic samples and incorporation of functional nanoparticles into the material. The synthesized materials showed excellent properties as an anode material in lithium batteries and support material for supercapacitors. N2 - Kohlenstoffmaterialien finden aufgrund ihrer Vielseitigkeit heute in den unterschiedlichsten Bereichen des täglichen Lebens ihren Einsatz. Bekannte Beispiele sind Kohlenstofffasern in Verbundwerkstoffen, Graphit als trockenes Schmiermittel, oder Aktivkohlen in Filtersystemen. Ferner wird Graphit als Elektrodenmaterial auch in Lithium-Ionen-Batterien verwendet. Wegen knapper werdender Ressourcen von Öl und Gas wurde in den letzten Jahren verstärkt an der Entwicklung neuer Materialien für die Speicherung von Wasserstoff und elektrischer Energie gearbeitet. Die Nanotechnologie ist dabei auch für neue Kohlenstoffmaterialien zukunftsweisend, denn sie stellt weitere Anwendungsmöglichkeiten in Aussicht. In dieser Arbeit wurden hierzu mittels des sogenannten Nanocastings neue Kohlenstoffmaterialien für Energieanwendungen, insbesondere zur Speicherung von elektrischer Energie entwickelt. Die Eigenschaften eines Kohlenstoffmaterials beruhen im Wesentlichen auf der Struktur des Kohlenstoffs im molekularen Bereich. Die in dieser Arbeit hergestellten Materialen bestehen aus nichtgraphitischem Kohlenstoff und wurden im ersten Teil der Arbeit mit den Methoden der Röntgenstreuung genau untersucht. Eine speziell für diese Art von Kohlenstoffen kürzlich entwickelte Modellfunktion wurde dazu an die experimentellen Streubilder angepasst. Das verwendete Modell basiert dabei auf den wesentlichen Strukturmerkmalen von nichtgraphitischem Kohlenstoff und ermöglichte von daher eine detaillierte Beschreibung der Materialien. Im Gegensatz zu den meisten nichtgraphitischen Kohlenstoffen konnte gezeigt werden, dass die Verwendung von Mesophasen-Pech als Vorläufersubstanz (Precursor) ein Material mit vergleichsweise geringem Grad an Unordnung ermöglicht. Solch ein Material erlaubt eine ähnlich reversible Einlagerung von Lithium-Ionen wie Graphit, weist aber gleichzeitig wegen des nichtgraphitischen Charakters eine deutlich höhere Speicherfähigkeit auf. Zur Beschreibung der Porosität eines Materials verwendet man die Begriffe der Makro-, Meso-, und Mikroporen. Die Aktivität eines Materials kann durch die Erhöhung der Oberfläche noch erheblich gesteigert werden. Hohe Oberflächen können insbesondere durch die Schaffung von Poren im Nanometerbereich erzielt werden. Um die Zugänglichkeit zu diesen Poren zu steigern, weist ein Material idealerweise zusätzlich ein kontinuierliches makroporöses Transportsystem (Porendurchmesser d > 50 nm) auf. Solch eine Art von Porosität über mehrere Größenordnungen wird allgemein als „hierarchische Porosität“ bezeichnet. Für elektrochemische Anwendungen sind sogenannte Mesoporen (d = 2 – 50 nm) relevant, da noch kleinere Poren (Mikroporen, d < 2 nm) z.B. zu einer irreversiblen Bindung von Lithium- Ionen führen können. Wird Mesophasen-Pech als Kohlenstoffprekursor verwendet, kann die Entstehung dieser Mikroporen verhindert werden. Im zweiten und dritten Teil der Arbeit konnte mit den Methoden des „Nanocastings“ zum ersten Mal die spezielle Struktur des Mesophasen-Pech basierenden Kohlenstoffmaterials mit den Vorteilen einer hierarchischen (makro- / meso-) Porosität kombiniert werden. Im ersten Syntheseverfahren wurde dazu ein sogenanntes „hartes Templat“ mit entsprechender Porosität aus Siliziumdioxid repliziert. Aufgrund der hohen Viskosität des Pechs und der geringen Löslichkeit wurde dazu ein Verfahren entwickelt, das die Infiltration des Templates auch auf der Nanometerebene ermöglicht. Das Material konnte in Form größerer Körper (Monolithen) hergestellt werden, die im Vergleich zu Pulvern eine bessere technische Verwendung ermöglichen. Im zweiten Syntheseverfahren konnte die Herstellung eines hierarchisch makro- / mesoporösen Kohlenstoffmaterials erstmals mittels eines weichen Templates (organisches Polymer) erreicht werden. Die einfache Entfernung von weichen Templaten durch eine geeignete Temperaturbehandlung, macht dieses Verfahren im Vergleich zu hart templatierten Materialien kostengünstiger und stellt eine technische Umsetzung in Aussicht. Desweiteren erlaubt das Syntheseverfahren die Herstellung von monolithischen Körpern und die Einbindung funktionaler Nanopartikel. Die hergestellten Materialien zeigen exzellente Eigenschaften als Elektrodenmaterial in Lithium-Ionen-Batterien und als Trägermaterial für Superkondensatoren. KW - Mesoporosität KW - hierarchische Porosität KW - weiche und harte Templatierung KW - Kohlenstoffmaterialien KW - Weitwinkelröntgenstreuung KW - Mesoporosity KW - hierarchical porosity KW - soft and hard templating KW - carbon materials KW - wide-angle x-ray scattering Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-15053 ER - TY - JOUR A1 - Agne, Stefanie A1 - Preick, Michaela A1 - Straube, Nicolas A1 - Hofreiter, Michael T1 - Simultaneous Barcode Sequencing of Diverse Museum Collection Specimens Using a Mixed RNA Bait Set JF - Frontiers in Ecology and Evolution N2 - A growing number of publications presenting results from sequencing natural history collection specimens reflect the importance of DNA sequence information from such samples. Ancient DNA extraction and library preparation methods in combination with target gene capture are a way of unlocking archival DNA, including from formalin-fixed wet-collection material. Here we report on an experiment, in which we used an RNA bait set containing baits from a wide taxonomic range of species for DNA hybridisation capture of nuclear and mitochondrial targets for analysing natural history collection specimens. The bait set used consists of 2,492 mitochondrial and 530 nuclear RNA baits and comprises specific barcode loci of diverse animal groups including both invertebrates and vertebrates. The baits allowed to capture DNA sequence information of target barcode loci from 84% of the 37 samples tested, with nuclear markers being captured more frequently and consensus sequences of these being more complete compared to mitochondrial markers. Samples from dry material had a higher rate of success than wet-collection specimens, although target sequence information could be captured from 50% of formalin-fixed samples. Our study illustrates how efforts to obtain barcode sequence information from natural history collection specimens may be combined and are a way of implementing barcoding inventories of scientific collection material. KW - target capture KW - type specimens KW - molecular species identification KW - museum specimens KW - cross-species capture Y1 - 2022 U6 - https://doi.org/10.3389/fevo.2022.909846 SN - 2296-701X VL - 10 PB - Frontiers Media S.A. CY - Lausanne, Schweiz ER - TY - GEN A1 - Albrecht, O. A1 - Cumming, W. A1 - Kreuder, W. A1 - Laschewsky, André A1 - Ringsdorf, Helmut T1 - Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface N2 - Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 079 KW - Monolayers KW - liquid crystals KW - discotics Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17124 ER - TY - GEN A1 - Allefeld, Carsten A1 - Frisch, Stefan A1 - Schlesewsky, Matthias T1 - Detection of early cognitive processing by event-related phase synchronization analysis N2 - In order to investigate the temporal characteristics of cognitive processing, we apply multivariate phase synchronization analysis to event-related potentials. The experimental design combines a semantic incongruity in a sentence context with a physical mismatch (color change). In the ERP average, these result in an N400 component and a P300-like positivity, respectively. The synchronization analysis shows an effect of global desynchronization in the theta band around 288ms after stimulus presentation for the semantic incongruity, while the physical mismatch elicits an increase of global synchronization in the alpha band around 204ms. Both of these effects clearly precede those in the ERP average. Moreover, the delay between synchronization effect and ERP component correlates with the complexity of the cognitive processes. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 074 KW - phase synchronization KW - coherence KW - semantic incongruity KW - color change KW - N400 KW - P300 KW - theta KW - alpha Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-20126 ER - TY - JOUR A1 - Aloui, Ali A1 - Tayech, Amel A1 - Arbi Mejri, Mohamed A1 - Makhlouf, Issam A1 - Clark, Cain C. T. A1 - Granacher, Urs A1 - Zouhal, Hassane A1 - Ben Abderrahman, Abderraouf T1 - Reliability and Validity of a New Taekwondo-Specific Change-of-Direction Speed Test With Striking Techniques in Elite Taekwondo Athletes: A Pilot Study JF - Frontiers in Physiology N2 - The purpose of this study was to examine the test-retest reliability, and convergent and discriminative validity of a new taekwondo-specific change-of-direction (COD) speed test with striking techniques (TST) in elite taekwondo athletes. Twenty (10 males and 10 females) elite (athletes who compete at national level) and top-elite (athletes who compete at national and international level) taekwondo athletes with an average training background of 8.9 ± 1.3 years of systematic taekwondo training participated in this study. During the two-week test-retest period, various generic performance tests measuring COD speed, balance, speed, and jump performance were carried out during the first week and as a retest during the second week. Three TST trials were conducted with each athlete and the best trial was used for further analyses. The relevant performance measure derived from the TST was the time with striking penalty (TST-TSP). TST-TSP performances amounted to 10.57 ± 1.08 s for males and 11.74 ± 1.34 s for females. The reliability analysis of the TST performance was conducted after logarithmic transformation, in order to address the problem of heteroscedasticity. In both groups, the TST demonstrated a high relative test-retest reliability (intraclass correlation coefficients and 90% compatibility limits were 0.80 and 0.47 to 0.93, respectively). For absolute reliability, the TST’s typical error of measurement (TEM), 90% compatibility limits, and magnitudes were 4.6%, 3.4 to 7.7, for males, and 5.4%, 3.9 to 9.0, for females. The homogeneous sample of taekwondo athletes meant that the TST’s TEM exceeded the usual smallest important change (SIC) with 0.2 effect size in the two groups. The new test showed mostly very large correlations with linear sprint speed (r = 0.71 to 0.85) and dynamic balance (r = −0.71 and −0.74), large correlations with COD speed (r = 0.57 to 0.60) and vertical jump performance (r = −0.50 to −0.65), and moderate correlations with horizontal jump performance (r = −0.34 to −0.45) and static balance (r = −0.39 to −0.44). Top-elite athletes showed better TST performances than elite counterparts. Receiver operating characteristic analysis indicated that the TST effectively discriminated between top-elite and elite taekwondo athletes. In conclusion, the TST is a valid, and sensitive test to evaluate the COD speed with taekwondo specific skills, and reliable when considering ICC and TEM. Although the usefulness of the TST is questioned to detect small performance changes in the present population, the TST can detect moderate changes in taekwondo-specific COD speed. KW - taekwondo-specific testing KW - sport-specific performance KW - striking combat sports KW - sensitivity KW - taekwondo electronic scoring system Y1 - 2022 U6 - https://doi.org/10.3389/fphys.2022.774546 SN - 1664-042X VL - 13 SP - 1 EP - 15 PB - Frontiers CY - Lausanne, Schweiz ER - TY - RPRT A1 - Amann, Erwin A1 - Rzepka, Sylvi T1 - The Effect of Goal-Setting Prompts in a Blended Learning Environment BT - Evidence from a Field Experiment T2 - CEPA Discussion Papers N2 - We investigate how inviting students to set task-based goals affects usage of an online learning platform and course performance. We design and implement a randomized field experiment in a large mandatory economics course with blended learning elements. The low-cost treatment induces students to use the online learning system more often, more intensively, and to begin earlier with exam preparation. Treated students perform better in the course than the control group: they are 18.8% (0.20 SD) more likely to pass the exam and earn 6.7% (0.19 SD) more points on the exam. There is no evidence that treated students spend significantly more time, rather they tend to shift to more productive learning methods. The heterogeneity analysis suggests that higher treatment effects are associated with higher levels of behavioral bias but also with poor early course behavior. T3 - CEPA Discussion Papers - 25 KW - natural field experiment KW - blended learning KW - behavioral economics KW - goal-setting Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-493476 SN - 2628-653X N1 - The trial is registered in the AEA RCT registry, RCT ID AEARCTR-28790 (https://doi.org/10.1257/rct.2928-1.0). IS - 25 ER - TY - RPRT A1 - Amoroso, Sara A1 - Herrmann, Benedikt A1 - Kritikos, Alexander T1 - The Role of Regulation and Regional Government Quality for High Growth Firms BT - The Good, the Bad, and the Ugly T2 - CEPA Discussion Papers N2 - High growth firms (HGFs) are important for job creation and considered to be precursors of economic growth. We investigate how formal institutions, like product- and labor-market regulations, as well as the quality of regional governments that implement these regulations, affect HGF development across European regions. Using data from Eurostat, OECD, WEF, and Gothenburg University, we show that both regulatory stringency and the quality of the regional government influence the regional shares of HGFs. More importantly, we find that the effect of labor- and product-market regulations ultimately depends on the quality of regional governments: in regions with high quality of government, the share of HGFs is neither affected by the level of product market regulation, nor by more or less flexibility in hiring and firing practices. Our findings contribute to the debate on the effects of regulations by showing that regulations are not, per se, “good, bad, and ugly”, rather their impact depends on the efficiency of regional governments. Our paper offers important building blocks to develop tailored policy measures that may influence the development of HGFs in a region. T3 - CEPA Discussion Papers - 71 KW - High growth firms KW - Regulation KW - Quality of regional governments KW - Regions Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-612771 SN - 2628-653X IS - 71 ER - TY - THES A1 - Andersen, Audrée T1 - Surfactant dynamics at interfaces : a series of second harmonic generation experiments T1 - Surfactant Dynamik an Grenzflächen : eine Studie über SHG-Experimente N2 - Adsorption layers of soluble surfactants enable and govern a variety of phenomena in surface and colloidal sciences, such as foams. The ability of a surfactant solution to form wet foam lamellae is governed by the surface dilatational rheology. Only systems having a non-vanishing imaginary part in their surface dilatational modulus, E, are able to form wet foams. The aim of this thesis is to illuminate the dissipative processes that give rise to the imaginary part of the modulus. There are two controversial models discussed in the literature. The reorientation model assumes that the surfactants adsorb in two distinct states, differing in their orientation. This model is able to describe the frequency dependence of the modulus E. However, it assumes reorientation dynamics in the millisecond time regime. In order to assess this model, we designed a SHG pump-probe experiment that addresses the orientation dynamics. Results obtained reveal that the orientation dynamics occur in the picosecond time regime, being in strong contradiction with the two states model. The second model regards the interface as an interphase. The adsorption layer consists of a topmost monolayer and an adjacent sublayer. The dissipative process is due to the molecular exchange between both layers. The assessment of this model required the design of an experiment that discriminates between the surface compositional term and the sublayer contribution. Such an experiment has been successfully designed and results on elastic and viscoelastic surfactant provided evidence for the correctness of the model. Because of its inherent surface specificity, surface SHG is a powerful analytical tool that can be used to gain information on molecular dynamics and reorganization of soluble surfactants. They are central elements of both experiments. However, they impose several structural elements of the model system. During the course of this thesis, a proper model system has been identified and characterized. The combination of several linear and nonlinear optical techniques, allowed for a detailed picture of the interfacial architecture of these surfactants. N2 - Amphiphile vereinen zwei gegensätzliche Strukturelemente in einem Molekül, eine hydrophile Kopfgruppe und ein hydrophobe, meist aliphatische Kette. Aufgrund der molekularen Asymmetrie erfolgt eine spontane Adsorption an der Wasser-Luft Grenzfläche. Die Adsorptionsschicht verändert die makroskopischen Eigenschaften des Materials, z.B. die Grenzflächenspannung wird erniedrigt. Amphiphile sind zentrale Bauelemente der Kolloid- und Grenzflächenforschung, die Phänomene, wie Schäume ermöglichen. Eine Schaumlamelle besteht aus einem dünnen Wasserfilm, der durch zwei Adsorptionsschichten stabilisiert wird. Die Stabilität der Lamelle wird durch die Grenzflächenrheologie entscheidend geprägt. Die wesentliche makroskopische Größe in diesem Zusammenhang ist das so genannte Grenzflächendilatationsmodul E. Es beschreibt die Fähigkeit des Systems die Gleichgewichtsgrenzflächenspannung nach einer Expansion oder Dilatation der Adsorptionschicht wieder herzustellen. Das Modul E ist eine komplexe Größe, in dem der Imaginärteil direkt mit der Schaumstabilität korreliert. Diese Arbeit widmet sich der Grenzflächenrheologie. In der Literatur werden zwei kontroverse Modelle zur Interpretation dieser Größe diskutiert. Diese Modelle werden experimentell in dieser Arbeit überprüft. Dies erfordert die Entwicklung neuer experimenteller Aufbauten basierend auf nichtlinearen, optischen Techniken. Mit diesen Experimenten konnte eines der Modelle bestätigt werden. KW - Tensid KW - Grenzflächenchemie KW - Nichtlineare Spektroskopie KW - Oscillating Bubble KW - surfactants KW - nonlinear optics KW - surface rheology KW - air-water interface KW - oscillating bubble Y1 - 2005 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6553 ER - TY - RPRT A1 - Andres, Maximilian A1 - Bruttel, Lisa Verena A1 - Friedrichsen, Jana T1 - How communication makes the difference between a cartel and tacit collusion BT - a machine learning approach T2 - CEPA Discussion Papers N2 - This paper sheds new light on the role of communication for cartel formation. Using machine learning to evaluate free-form chat communication among firms in a laboratory experiment, we identify typical communication patterns for both explicit cartel formation and indirect attempts to collude tacitly. We document that firms are less likely to communicate explicitly about price fixing and more likely to use indirect messages when sanctioning institutions are present. This effect of sanctions on communication reinforces the direct cartel-deterring effect of sanctions as collusion is more difficult to reach and sustain without an explicit agreement. Indirect messages have no, or even a negative, effect on prices. T3 - CEPA Discussion Papers - 53 KW - cartel KW - collusion KW - communication KW - machine learning KW - experiment Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-562234 SN - 2628-653X ER -