Refine
Year of publication
Document Type
- Article (594)
- Preprint (299)
- Postprint (257)
- Conference Proceeding (160)
- Doctoral Thesis (51)
- Working Paper (48)
- Review (36)
- Monograph/Edited Volume (26)
- Part of a Book (24)
- Other (16)
Language
- English (1515) (remove)
Is part of the Bibliography
- no (1515) (remove)
Keywords
- Curriculum Framework (31)
- European values education (31)
- Europäische Werteerziehung (31)
- Familie (31)
- Family (31)
- Lehrevaluation (31)
- Studierendenaustausch (31)
- Unterrichtseinheiten (31)
- curriculum framework (31)
- lesson evaluation (31)
Institute
- Institut für Mathematik (309)
- Extern (259)
- Institut für Physik und Astronomie (119)
- Vereinigung für Jüdische Studien e. V. (108)
- Department Linguistik (91)
- Department Psychologie (86)
- Institut für Chemie (65)
- Hasso-Plattner-Institut für Digital Engineering GmbH (55)
- Historisches Institut (52)
- Institut für Umweltwissenschaften und Geographie (49)
Absorption and fluorescence properties of 4 hydraulic oils (3 biological and 1 petroleum-based) were investigated. In-situ LIF (laser-induced fluorescence) analysis of the oils on a brown sandy loam soil was performed. With calibration, quantitative detection was achieved. Estimated limits of detection were below ca. 500 mg/kg for the petroleum-based oil and ca. 2000 mg/kg for one biological oil. A semi-quantitative classification scheme is proposed for monitoring of the biological oils. This approach was applied to investigate the migration of a biological oil in soil-containing compartments, namely a soil column and a soil bed.
Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.
Steady-state and time-resolved fluorescence methods were applied to investigate the fluorescence properties of humic substances of different origins. Using standard 2D emission and total luminescence spectra, fluorescence maxima, the width of the fluorescence band and a relative fluorescence quantum efficiency were determined. Different trends for fulvic acids and humic acids were observed indicating differences in the heterogeneity of the sample fractions. The complexity of the fluorescence decay of humic substances is discussed and compared to simple model compounds. The effect of oxidation of humic substances on their fluorescence properties is discussed as well.
In a recent contribution in Nature (vol. 442, pp. 555-558) Austin & Vivanco showed that sunlight is the dominant factor for decomposition of grass litter in a semi-arid grassland in Argentine. The quantification of this effect was portrayed as a novel finding. I put this result in the context of three other publications from as early as 1980 that quantified photodegradation. My synopsis shows that photodegradation is an important process in semi-arid grasslands in South America, North America and eastern Europe.
In the present study, photophysical properties of [N]phenylenes were studied by means of stationary and time-resolved absorption and fluorescence spectroscopy (in THF at room temperature). For biphenylene (1) and linear [3]phenylene (2a), internal conversion (IC) with quantum yields ΦIC > 0.99 is by far the dominant mechanism of S1 state deactivation. Angular [3]phenylene (3a), the zig-zag [4]- and [5]phenylenes (3b), (3c), and the triangular [4]phenylene (4) show fluorescence emission with fluorescence quantum yieds and lifetimes between ΦF = 0.07 for (3a) and 0.21 for (3c) and τF = 20 ns for (3a) and 81 ns for (4). Also, compounds (3) and (4) exhibit triplet formation upon photoexcitation with quantum yields as high as ΦISC = 0.45 for (3c). The strong differences in the fluorescence properties and in the triplet fromation efficiencies between (1) and (2a) on one hand and (3) and (4) on the other are related to the remarkable variation of the internal conversion (IC) rate constants kIC. A tentative classification of (1) and (2a) as “fast IC compounds”, with kIC > 109 s-1, and of (3) and (4) as “slow IC compounds”, with kIC ≈ 107 s-1, is suggested. This classification cannot simply be related to Hückel’s rule-type concepts of aromaticity, because the group of “fast IC compounds” consists of “antiaromatic” (1) and “aromatic” (2a), and the group of “slow IC compounds” consists of “antiaromatic” (3b), (4) and “aromatic” (3a), (3c). The IC in the [N]phenylenes is discussed within the framework of the so-called energy gap law established for non-radiative processes in benzenoid hydrocarbons.
The drift time spectra of polycyclic aromatic hydrocarbons (PAH), alkylbenzenes and alkylphenylethers were recorded with a laser-based ion mobility (IM) spectrometer. The ion mobilities of all compounds were determined in helium as drift gas. This allows the calculation of the diffusion cross sections (Omegacalc) on the basis of the exact hard sphere scattering model (EHSSM) and their comparison with the experimentally determined diffusion cross sections (Omegaexp). These Omegaexp/Omegacalc-correlations are presented for molecules with a rigid structure like PAH and prove the reliability of the theoretical model and experimental method. The increase of the selectivity of IM spectrometry is demonstrated using resonance enhanced multiphoton ionisation (REMPI) at atmospheric pressure, realized by tuneable lasers. The REMPI spectra of nine alkylbenzenes and alkylphenylethers are investigated. On the basis of these spectra, the complete qualitative distinction of eight compounds in a mixture is shown. These experiments are extended to alkylbenzene isomer mixtures.
Semiclassical asymptotics for the scattering amplitude in the presence of focal points at infinity
(2006)
We consider scattering in $\R^n$, $n\ge 2$, described by the Schr\"odinger operator $P(h)=-h^2\Delta+V$, where $V$ is a short-range potential. With the aid of Maslov theory, we give a geometrical formula for the semiclassical asymptotics as $h\to 0$ of the scattering amplitude $f(\omega_-,\omega_+;\lambda,h)$ $\omega_+\neq\omega_-$) which remains valid in the presence of focal points at infinity (caustics). Crucial for this analysis are precise estimates on the asymptotics of the classical phase trajectories and the relationship between caustics in euclidean phase space and caustics at infinity.
This paper focuses on some of the factors explaining recent trends in decentralisation, and some areas where decentralisation has had a positive impact, including bringing citizens into public affairs, improving sub-national public administration, and stimulating local economic development. It concludes by exploring the dangers and the implications for governments of differing capabilities starting out on the decentralisation path. More specifically, the paper stresses the underlying incentive structures within states in reform. It suggests a country-specific discussion of both vertical and horizontal incentive structures in decentralisation, as well as clear-cut accountability within a public sector in change. While vertical incentive structures mean defined rules for intergovernmental relationships, horizontal incentive structures mean defined rules between local governments, their citizens and the local private sector. Both sets of incentives need to be reformed jointly to stimulate better results from decentralisation and for better performance of local government. Neglecting one of them, could harm development. Above all, politics and processes are key to understanding, and eventually, managing decentralisation effectively.
The end of the cold war division of the Baltic Sea in 1989, and the three Baltic states’ return to independence in 1991 created new opportunities for the decision-makers of the area, as well as new possibilities for fashioning security in the region. This article will examine the security debate affecting the Baltic Sea region in the post-cold war period, and in particular, the relevance of the European Union to that debate. The following section will examine various concepts of security relevant to the Baltic region; the third section looks at the EU and the Baltic area; and the last part deals with the implications that EU membership by the Baltic Sea states may have for the security of the Baltic Sea zone.
The article mobilises the concept of strategic culture in order to identify the impact of history upon contemporary security policy. The article will first look at the "wholesale construction" of a strategic culture after the Second World War in West Germany before exploring its impact upon security policy since the end of the Cold War in two areas: the Bundeswehr's out-of-area role and conscription. The central argument presented here is that the strategic culture of the former Federal Republic now writ large on to the new united Germany sets the context within which security policies are designed. This strategic culture, as will be argued, acts as both a facilitating and a restraining variable on behaviour, making certain policy options possible and others impossible.
Observers of international politics have been conscious of the growing international involvement of non-central governments (NCGs), particularly in federal systems. These have been supplemented by the internationalisation of subnational actors in quasi-federal and even unitary states. One of the difficulties is that analysis has often been locked into the dominant paradigm debate in International Relations concerning who and who are not significant actors. Having briefly explored the nature of this changing environment, marked by a growing emphasis on access rather than control as a policy objective and the emergence of what is termed a 'catalytic diplomacy', the discussion focuses on the need for linkage between the levels of government in the pursuit of international as well as domestic policy goals. The nature of linkage mechanisms are discussed.
On the basis of the Dynamic Syntax framework, this paper argues that the production pressures in dialogue determining alignment effects and given versus new informational effects also drive the shift from case-rich free word order systems without clitic pronouns into systems with clitic pronouns with rigid relative ordering. The paper introduces assumptions of Dynamic Syntax, in particular the building up of interpretation through structural underspecification and update, sketches the attendant account of production with close coordination of parsing and production strategies, and shows how what was at the Latin stage a purely pragmatic, production-driven decision about linear ordering becomes encoded in the clitics in theMedieval Spanish system which then through successive steps of routinization yield the modern systems with immediately pre-verbal fixed clitic templates.
We analyze anaphoric phenomena in the context of building an input understanding component for a conversational system for tutoring mathematics. In this paper, we report the results of data analysis of two sets of corpora of dialogs on mathematical theorem proving. We exemplify anaphoric phenomena, identify factors relevant to anaphora resolution in our domain and extensions to the input interpretation component to support it.
Received views of utterance context in pragmatic theory characterize the occurrent subjective states of interlocutors using notions like common knowledge or mutual belief. We argue that these views are not compatible with the uncertainty and robustness of context-dependence in humanhuman dialogue. We present an alternative characterization of utterance context as objective and normative. This view reconciles the need for uncertainty with received intuitions about coordination and meaning in context, and can directly inform computational approaches to dialogue.
Goal-oriented dialog as a collaborative subordinated activity involving collective acceptance
(2006)
Modeling dialog as a collaborative activity consists notably in specifying the contain of the Conversational Common Ground and the kind of social mental state involved. In previous work (Saget, 2006), we claim that Collective Acceptance is the proper social attitude for modeling Conversational Common Ground in the particular case of goal-oriented dialog. We provide a formalization of Collective Acceptance, besides elements in order to integrate this attitude in a rational model of dialog are provided; and finally, a model of referential acts as being part of a collaborative activity is provided. The particular case of reference has been chosen in order to exemplify our claims.
A key problem for models of dialogue is to explain the mechanisms involved in generating and responding to clarification requests. We report a 'Maze task' experiment that investigates the effect of 'spoof' clarification requests on the development of semantic co-ordination. The results provide evidence of both local and global semantic co-ordination phenomena that are not captured by existing dialogue co-ordination models.
How does a shared lexicon arise in population of agents with differing lexicons, and how can this shared lexicon be maintained over multiple generations? In order to get some insight into these questions we present an ALife model in which the lexicon dynamics of populations that possess and lack metacommunicative interaction (MCI) capabilities are compared. We ran a series of experiments on multi-generational populations whose initial state involved agents possessing distinct lexicons. These experiments reveal some clear differences in the lexicon dynamics of populations that acquire words solely by introspection contrasted with populations that learn using MCI or using a mixed strategy of introspection and MCI. The lexicon diverges at a faster rate for an introspective population, eventually collapsing to one single form which is associated with all meanings. This contrasts sharply with MCI capable populations in which a lexicon is maintained, where every meaning is associated with a unique word. We also investigated the effect of increasing the meaning space and showed that it speeds up the lexicon divergence for all populations irrespective of their acquisition method.
Demonstratives, in particular gestures that "only" accompany speech, are not a big issue in current theories of grammar. If we deal with gestures, fixing their function is one big problem, the other one is how to integrate the representations originating from different channels and, ultimately, how to determine their composite meanings. The growing interest in multi-modal settings, computer simulations, human-machine interfaces and VRapplications increases the need for theories ofmultimodal structures and events. In our workshopcontribution we focus on the integration of multimodal contents and investigate different approaches dealing with this problem such as Johnston et al. (1997) and Johnston (1998), Johnston and Bangalore (2000), Chierchia (1995), Asher (2005), and Rieser (2005).
A new method is used in an eye-tracking pilot experiment which shows that it is possible to detect differences in common ground associated with the use of minimally different types of indefinite anaphora. Following Richardson and Dale (2005), cross recurrence quantification analysis (CRQA) was used to show that the tandem eye movements of two Swedish-speaking interlocutors are slightly more coupled when they are using fully anaphoric indefinite expressions than when they are using less anaphoric indefinites. This shows the potential of CRQA to detect even subtle processing differences in ongoing discourse.
Verbal or visual? : How information is distributed across speech and gesture in spatial dialog
(2006)
In spatial dialog like in direction giving humans make frequent use of speechaccompanying gestures. Some gestures convey largely the same information as speech while others complement speech. This paper reports a study on how speakers distribute meaning across speech and gesture, and depending on what factors. Utterance meaning and the wider dialog context were tested by statistically analyzing a corpus of direction-giving dialogs. Problems of speech production (as indicated by discourse markers and disfluencies), the communicative goals, and the information status were found to be influential, while feedback signals by the addressee do not have any influence.