@article{GuentnerKroldeArajoetal.2004,
  author    = {G{\"u}ntner, Andreas and Krol, Marten S. and de Arajo, Jos{\´e} Carlos and Bronstert, Axel},
  title     = {Simple water balance modelling of surface reservoir systems in a large data-scarce semiarid region},
  issn      = {0262-6667},
  year      = {2004},
  abstract  = {Water resources in dryland areas are often provided by numerous surface reservoirs. As a basis for securing future water supply, the dynamics of reservoir systems need to be simulated for large river basins, accounting for environmental change and an increasing water demand. For the State of Ceara in semiarid Northeast Brazil, with several thousands of reservoirs, a simple deterministic water balance model is presented. Within a cascade-type approach, the reservoirs are grouped into six classes according to storage capacity, rules for flow routing between reservoirs of different size are defined, and water withdrawal and return flow due to human water use is accounted for. While large uncertainties in model applications exist, particularly in terms of reservoir operation rules, model validation against observed reservoir storage volumes shows that the approach is a reasonable simplification to assess surface water availability in large river basins. The results demonstrate the large impact of reservoir storage on downstream flow and stress the need for a coupled simulation of runoff generation, network redistribution and water use},
  language  = {en}
}
@article{SchulzeSeiler2004,
  author    = {Schulze, Bert-Wolfgang and Seiler, J{\"o}rg},
  title     = {Boundary value problems with global projection conditions},
  issn      = {0022-1236},
  year      = {2004},
  abstract  = {Parametrices of elliptic boundary value problems for differential operators belong to an algebra of pseudodifferential operators with the transmission property at the boundary. However, generically, smooth symbols on a manifold with boundary do not have this property, and several interesting applications require a corresponding more general calculus. We introduce here a new algebra of boundary value problems that contains Shapiro-Lopatinskij elliptic as well as global projection conditions; the latter ones are necessary, if an analogue of the Atiyah-Bott obstruction does not vanish. We show that every elliptic operator admits (up to a stabilisation) elliptic conditions of that kind. Corresponding boundary value problems are then Fredholm in adequate scales of spaces. Moreover, we construct parametrices in the calculus. (C) 2003 Elsevier Inc. All rights reserved},
  language  = {en}
}
@article{BlumeBauerBronstert2004,
  author    = {Blume, Theresa and Bauer, Andreas and Bronstert, Axel},
  title     = {Experimental techniques for the Investigation of Runoff Processes in a Small Catchment in the Chilean Andes},
  isbn      = {3-937758-18-6},
  year      = {2004},
  language  = {en}
}
@article{RabinovichSchulzeTarkhanov2004,
  author    = {Rabinovich, Vladimir and Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
  title     = {Boundary value problems in oscillating cuspidal wedges},
  issn      = {0035-7596},
  year      = {2004},
  abstract  = {The paper is devoted to pseudodifferential boundary value problems in domains with cuspidal wedges. We show a criterion for the Fredholm property of a boundary value problem and derive estimates of solutions close to edges},
  language  = {en}
}
@article{FedosovSchulzeTarkhanov2004,
  author    = {Fedosov, Boris and Schulze, Bert-Wolfgang and Tarkhanov, Nikolai Nikolaevich},
  title     = {On the index theorem for symplectic orbifolds},
  issn      = {0373-0956},
  year      = {2004},
  abstract  = {We give an explicit construction of the trace on the algebra of quantum observables on a symplectiv orbifold and propose an index formula},
  language  = {en}
}
@article{NazajkinskijSavinSterninetal.2004,
  author    = {Nazajkinskij, Vladimir E. and Savin, Anton and Sternin, Boris Ju. and Schulze, Bert-Wolfgang},
  title     = {On the index of differential operators on manifolds with edges},
  issn      = {1064-5624},
  year      = {2004},
  language  = {en}
}
@article{NazajkinskijSavinSterninetal.2004,
  author    = {Nazajkinskij, Vladimir E. and Savin, Anton and Sternin, Boris Ju. and Schulze, Bert-Wolfgang},
  title     = {On the existence of elliptic problems on manifolds with edges},
  issn      = {1064-5624},
  year      = {2004},
  language  = {en}
}
@article{NazajkinskijSavinSterninetal.2004,
  author    = {Nazajkinskij, Vladimir E. and Savin, Anton and Sternin, Boris Ju. and Schulze, Bert-Wolfgang},
  title     = {Pseudodifferential operators on manifolds with edges},
  issn      = {1064-5624},
  year      = {2004},
  language  = {en}
}
@unpublished{KrainerSchulze2004,
  author    = {Krainer, Thomas and Schulze, Bert-Wolfgang},
  title     = {The conormal symbolic structure of corner boundary value problems},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26662},
  year      = {2004},
  abstract  = {Ellipticity of operators on manifolds with conical singularities or parabolicity on space-time cylinders are known to be linked to parameter-dependent operators (conormal symbols) on a corresponding base manifold. We introduce the conormal symbolic structure for the case of corner manifolds, where the base itself is a manifold with edges and boundary. The specific nature of parameter-dependence requires a systematic approach in terms of meromorphic functions with values in edge-boundary value problems. We develop here a corresponding calculus, and we construct inverses of elliptic elements.},
  language  = {en}
}
@unpublished{NazaikinskiiSavinSchulzeetal.2004,
  author    = {Nazaikinskii, Vladimir and Savin, Anton and Schulze, Bert-Wolfgang and Sternin, Boris},
  title     = {Differential operators on manifolds with singularities : analysis and topology : Chapter 7: The index problem on manifolds with singularities},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26700},
  year      = {2004},
  abstract  = {Contents: Chapter 7: The Index Problemon Manifolds with Singularities Preface 7.1. The Simplest Index Formulas 7.1.1. General properties of the index 7.1.2. The index of invariant operators on the cylinder 7.1.3. Relative index formulas 7.1.4. The index of general operators on the cylinder 7.1.5. The index of operators of the form 1 + G with a Green operator G 7.1.6. The index of operators of the form 1 + G on manifolds with edges 7.1.7. The index on bundles with smooth base and fiber having conical points 7.2. The Index Problem for Manifolds with Isolated Singularities 7.2.1. Statement of the index splitting problem 7.2.2. The obstruction to the index splitting 7.2.3. Computation of the obstruction in topological terms 7.2.4. Examples. Operators with symmetries 7.3. The Index Problem for Manifolds with Edges 7.3.1. The index excision property 7.3.2. The obstruction to the index splitting 7.4. Bibliographical Remarks},
  language  = {en}
}
@unpublished{HarutjunjanSchulze2004,
  author    = {Harutjunjan, Gohar and Schulze, Bert-Wolfgang},
  title     = {Boundary problems with meromorphic symbols in cylindrical domains},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26735},
  year      = {2004},
  abstract  = {We show relative index formulas for boundary value problems in cylindrical domains and Sobolev spaces with different weigths at ±∞. The amplitude functions are meromorphic in the axial covariable and take values in the space of boundary value problems on the cross section of the cylinder.},
  language  = {en}
}
@article{DelgrandeSchaub2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten},
  title     = {Reasoning with sets of preferences in default logic},
  issn      = {0824-7935},
  year      = {2004},
  abstract  = {We present a general approach for representing and reasoning with sets of defaults in default logic, focusing on reasoning about preferences among sets of defaults. First, we consider how to control the application of a set of defaults so that either all apply (if possible) or none do (if not). From this, an approach to dealing with preferences among sets of default rules is developed. We begin with an ordered default theory, consisting of a standard default theory, but with possible preferences on sets of rules. This theory is transformed into a second, standard default theory wherein the preferences are respected. The approach differs from other work, in that we obtain standard default theories and do not rely on prioritized versions of default logic. In practical terms this means we can immediately use existing default logic theorem provers for an implementation. Also, we directly generate just those extensions containing the most preferred applied rules; in contrast, most previous approaches generate all extensions, then select the most preferred. In a major application of the approach, we show how semimonotonic default theories can be encoded so that reasoning can be carried out at the object level. With this, we can reason about default extensions from within the framework of a standard default logic. Hence one can encode notions such as skeptical and credulous conclusions, and can reason about such conclusions within a single extension},
  language  = {en}
}
@article{DelgrandeSchaubTompitsetal.2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten and Tompits, Hans and Wang, Kewen},
  title     = {A classification and survey of preference handling approchaches in nonmonotonic reasoning},
  issn      = {0824-7935},
  year      = {2004},
  abstract  = {In recent years, there has been a large amount of disparate work concerning the representation and reasoning with qualitative preferential information by means of approaches to nonmonotonic reasoning. Given the variety of underlying systems, assumptions, motivations, and intuitions, it is difficult to compare or relate one approach with another. Here, we present an overview and classification for approaches to dealing with preference. A set of criteria for classifying approaches is given, followed by a set of desiderata that an approach might be expected to satisfy. A comprehensive set of approaches is subsequently given and classified with respect to these sets of underlying principles},
  language  = {en}
}
@article{BorchertAngerSchaubetal.2004,
  author    = {Borchert, P. and Anger, Christian and Schaub, Torsten and Truszczynski, M.},
  title     = {Towards systematic benchmarking in answer set programming : the dagstuhl initiative},
  isbn      = {3-540- 20721-x},
  year      = {2004},
  language  = {en}
}
@article{DelgrandeSchaub2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten},
  title     = {Consistency-based approaches to merging knowledge based : preliminary report},
  isbn      = {92-990021-0-X},
  year      = {2004},
  language  = {en}
}
@article{KonczakLinkeSchaub2004,
  author    = {Konczak, Kathrin and Linke, Thomas and Schaub, Torsten},
  title     = {Graphs and cologings for answer set programming : adridged report},
  isbn      = {3-540- 20721-x},
  year      = {2004},
  language  = {en}
}
@article{FloeterSelbigSchaub2004,
  author    = {Fl{\"o}ter, Andr{\´e} and Selbig, Joachim and Schaub, Torsten},
  title     = {Finding metabolic pathways in decision forests},
  isbn      = {3-540-23221-4},
  year      = {2004},
  language  = {en}
}
@article{BoeselLinkeSchaub2004,
  author    = {Boesel, Andreas and Linke, Thomas and Schaub, Torsten},
  title     = {Profiling answer set programming : the visualization component of the noMoRe System},
  isbn      = {3-540-23242-7},
  year      = {2004},
  language  = {en}
}
@article{DelgrandeSchaubTompits2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten and Tompits, Hans},
  title     = {Domain-specific preference for causal reasoning and planning},
  isbn      = {1-577-35201-7},
  year      = {2004},
  language  = {en}
}
@article{DelgrandeSchaub2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten},
  title     = {Two approaches to merging knowledge bases},
  isbn      = {3-540-23242-7},
  year      = {2004},
  language  = {en}
}
@article{DelgrandeSchaubTompitsetal.2004,
  author    = {Delgrande, James Patrick and Schaub, Torsten and Tompits, Hans and Woltran, Stefan},
  title     = {On Computing belief change operations using quantifield boolean formulas},
  issn      = {0955-792X},
  year      = {2004},
  abstract  = {In this paper, we show how an approach to belief revision and belief contraction can be axiomatized by means of quantified Boolean formulas. Specifically, we consider the approach of belief change scenarios, a general framework that has been introduced for expressing different forms of belief change. The essential idea is that for a belief change scenario (K, R, C), the set of formulas K, representing the knowledge base, is modified so that the sets of formulas R and C are respectively true in, and consistent with the result. By restricting the form of a belief change scenario, one obtains specific belief change operators including belief revision, contraction, update, and merging. For both the general approach and for specific operators, we give a quantified Boolean formula such that satisfying truth assignments to the free variables correspond to belief change extensions in the original approach. Hence, we reduce the problem of determining the results of a belief change operation to that of satisfiability. This approach has several benefits. First, it furnishes an axiomatic specification of belief change with respect to belief change scenarios. This then leads to further insight into the belief change framework. Second, this axiomatization allows us to identify strict complexity bounds for the considered reasoning tasks. Third, we have implemented these different forms of belief change by means of existing solvers for quantified Boolean formulas. As well, it appears that this approach may be straightforwardly applied to other specific approaches to belief change},
  language  = {en}
}
@article{FloeterNicolasSchaubetal.2004,
  author    = {Fl{\"o}ter, Andr{\´e} and Nicolas, Jacques and Schaub, Torsten and Selbig, Joachim},
  title     = {Threshold extraction in metabolite concentration data},
  year      = {2004},
  abstract  = {Motivation: Continued development of analytical techniques based on gas chromatography and mass spectrometry now facilitates the generation of larger sets of metabolite concentration data. An important step towards the understanding of metabolite dynamics is the recognition of stable states where metabolite concentrations exhibit a simple behaviour. Such states can be characterized through the identification of significant thresholds in the concentrations. But general techniques for finding discretization thresholds in continuous data prove to be practically insufficient for detecting states due to the weak conditional dependences in concentration data. Results: We introduce a method of recognizing states in the framework of decision tree induction. It is based upon a global analysis of decision forests where stability and quality are evaluated. It leads to the detection of thresholds that are both comprehensible and robust. Applied to metabolite concentration data, this method has led to the discovery of hidden states in the corresponding variables. Some of these reflect known properties of the biological experiments, and others point to putative new states},
  language  = {en}
}
@article{SarsakovSchaubTompitsetal.2004,
  author    = {Sarsakov, Vladimir and Schaub, Torsten and Tompits, Hans and Woltran, Stefan},
  title     = {A compiler for nested logic programming},
  isbn      = {3-540- 20721-x},
  year      = {2004},
  language  = {en}
}
@article{OskinovaFeldmeierHamann2004,
  author    = {Oskinova, Lidia M. and Feldmeier, Achim and Hamann, Wolf-Rainer},
  title     = {X-ray emission lines from inhomogeneous stellar winds},
  issn      = {0004-6361},
  year      = {2004},
  abstract  = {It is commonly adopted that X-rays from O stars are produced deep inside the stellar wind, and transported outwards through the bulk of the expanding matter which attenuates the radiation and affects the shape of emission line profiles. The ability of the X-ray observatories Chandra and XMM-Newton to resolve these lines spectroscopically provided a stringent test for the theory of the X-ray production. It turned out that none of the existing models was able to fit the observations consistently. The possible caveat of these models was the underlying assumption of a smooth stellar wind. Motivated by the evidence that the stellar winds are in fact structured, we present a 2-D numerical model of a stochastic, inhomogeneous wind. Small parcels of hot, X-ray emitting gas are permeated by cool, absorbing wind material which is compressed into thin shell fragments. Wind fragmentation alters the radiative transfer drastically, compared to homogeneous models of the same mass-loss rate. X-rays produced deep inside the wind, which would be totally absorbed in a homogeneous flow, can effectively escape from a fragmented wind. The wind absorption becomes wavelength independent if the individual fragments are optically thick. The X-ray line profiles are flat-topped in the blue part and decline steeply in the red part for the winds with a short acceleration zone. For the winds where the acceleration extends over significant distances, the lines can appear nearly symmetric and only slightly blueshifted, in contrast to the skewed, triangular line profiles typically obtained from homogeneous wind models of high optical depth. We show that profiles from a fragmented wind model can reproduce the observed line profiles from zeta Orionis. The present numerical modeling confirms the results from a previous study, where we derived analytical formulae from a statistical treatment},
  language  = {en}
}
@article{BrownBarrettOskinovaetal.2004,
  author    = {Brown, John C. and Barrett, R. K. and Oskinova, Lidia M. and Owocki, S. P. and Hamann, Wolf-Rainer and de Jong, J. A. and Kaper, L. and Henrichs, H. F.},
  title     = {Inference of hot star density stream properties from data on rotationally recurrent DACs},
  issn      = {0004-6361},
  year      = {2004},
  abstract  = {The information content of data on rotationally periodic recurrent discrete absorption components (DACs) in hot star wind emission lines is discussed. The data comprise optical depths tau(w,phi) as a function of dimensionless Doppler velocity w=(Deltalambda/lambda(0))(c/v(infinity)) and of time expressed in terms of stellar rotation angle phi. This is used to study the spatial distributions of density, radial and rotational velocities, and ionisation structures of the corotating wind streams to which recurrent DACs are conventionally attributed. The simplifying assumptions made to reduce the degrees of freedom in such structure distribution functions to match those in the DAC data are discussed and the problem then posed in terms of a bivariate relationship between tau(w, phi) and the radial velocity v(r)(r), transverse rotation rate Omega(r) and density rho(r, phi) structures of the streams. The discussion applies to cases where: the streams are equatorial; the system is seen edge on; the ionisation structure is approximated as uniform; the radial and transverse velocities are taken to be functions only of radial distance but the stream density is allowed to vary with azimuth. The last kinematic assumption essentially ignores the dynamical feedback of density on velocity and the relationship of this to fully dynamical models is discussed. The case of narrow streams is first considered, noting the result of Hamann et al. (2001) that the apparent acceleration of a narrow stream DAC is higher than the acceleration of the matter itself, so that the apparent slow acceleration of DACs cannot be attributed to the slowness of stellar rotation. Thus DACs either involve matter which accelerates slower than the general wind flow, or they are formed by structures which are not advected with the matter flow but propagate upstream (such as Abbott waves). It is then shown how, in the kinematic model approximation, the radial speed of the absorbing matter can be found by inversion of the apparent acceleration of the narrow DAC, for a given rotation law. The case of broad streams is more complex but also more informative. The observed tau(w,phi) is governed not only by v(r)(r) and Omega(r) of the absorbing stream matter but also by the density profile across the stream, determined by the azimuthal (phi(0)) distribution function F- 0(phi(0)) of mass loss rate around the stellar equator. When F-0(phi(0)) is fairly wide in phi(0), the acceleration of the DAC peak tau(w, phi) in w is generally slow compared with that of a narrow stream DAC and the information on v(r)(r), Omega(r) and F-0(phi(0)) is convoluted in the data tau(w, phi). We show that it is possible, in this kinematic model, to recover by inversion, complete information on all three distribution functions v(r)(r), Omega(r) and F- 0(phi(0)) from data on tau(w, phi) of sufficiently high precision and resolution since v(r)(r) and Omega(r) occur in combination rather than independently in the equations. This is demonstrated for simulated data, including noise effects, and is discussed in relation to real data and to fully hydrodynamic models},
  language  = {en}
}
@phdthesis{Laubrock2004,
  author    = {Laubrock, Jochen},
  title     = {Proportional slowing in old adults is modulated by episodic memory demands : an investigation of age-related slowing using compatible and arbitrary stimulus-response mappings},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001782},
  school      = {Universit{\"a}t Potsdam},
  year      = {2004},
  abstract  = {Das dominante Datenmuster im Bereich des kognitiven Alterns ist der Alters-x-Komplexit{\"a}tseffekt. Die vorliegende Studie untersucht, ob das Muster statt durch einen {\"u}blicherweise postulierten unspezifischen durch einen spezifischen Mechanismus erkl{\"a}rt werden kann: die mit dem Alter abnehmende Reliabilit{\"a}t episodischer Akkumulatoren. In sechs Reaktionszeit-Experimenten wurden junge und {\"a}ltere Erwachsene verglichen, dabei wurden fr{\"u}he kognitive (Stroop-Bedingung) und episodische Schwierigkeit (Reiz-Reaktions-Zuordnung) orthogonal manipuliert. Die vorhergesagte Dreifachinteraktion der beiden Faktoren mit dem Alter zeigte sich {\"u}ber die Experimente hinweg relativ konsistent. Eine modifizierte Brinley-Analyse ergibt deutlich unterschiedliche Steigungen der Regressionsgeraden im Alt-Jung-Raum f{\"u}r niedrige und hohe episodische Schwierigkeit. Als methodischer Beitrag wird im Anhang ein zur modifizierten Brinley-Analyse passendes Regressionsmodell entwickelt, das aus einigen einfachen Verarbeitungsannahmen folgt. Es wird gezeigt, dass in einer klassischen Brinley Metaanalyse die Steigung neben der theoretisch interessierenden Varianz von theoretisch uninteressanter Zwischen-Experiment-Varianz beeinflusst wird.},
  language  = {en}
}
@article{Oberauer2004,
  author    = {Oberauer, Klaus},
  title     = {Simultaneous execution of two cognitive operations : Evidence from a continuous updating paradigm},
  year      = {2004},
  language  = {en}
}
@article{EgbeKietzkeCarbonnieretal.2004,
  author    = {Egbe, D. A. M. and Kietzke, Thomas and Carbonnier, B. and Muhlbacher, D. and Horhold, H. H. and Neher, Dieter and Pakula, T.},
  title     = {Synthesis, characterization, and photophysical, electrochemical, electroluminescent, and photovoltaic properties of yne-containing CN-PPVs},
  year      = {2004},
  abstract  = {Alkoxy-substituted CN-containing phenylene-vinylene-alt-phenylene-ethynylene hybrid polymers (CN-PPV-PPE), 3a, 3b, and 7a, were obtained from luminophoric dialdehydes 1 by step growth polymerization via Knoevenagel reaction as high molecular-weight materials. Corresponding CN-free polymers 3c and 7b and an ethynylene-free polymer 5 with similar side chains were synthesized for the purpose of comparison. The chemical structures of the polymers were confirmed by IR, H-1 and C-13 NMR, and elemental analysis. Thermal characterization was conducted by means of thermogravimetric analysis and differential scanning calorimetry. Morphology was investigated by means of optical microscopy and small-angle light scattering. The final morphologies are determined by the molecular characteristics (side chains volume fraction, backbone stiffness) of the studied polymers. All the CN-containing polymers 3b, 5, and 7a exhibit higher fluorescence quantum yield in solid state (50 to 60\%), but lower quantum yields (12-40\%) in dilute chloroform solution, in total contrast to CN-free polymers 3c, 3d, and 7b. Identical optical, E-g(opt), and electrochemical band gap energies, E- g(ec), were obtained for 3b, 3c and 3d with intrinsic self-assembly ability, whereas a discrepancy, DeltaE(g), was observed in the cases of the fully substituted polymers 5, 7a, and 7b, whose values are dependent on the level of backbone stiffness and length of the side groups combined with the presence or absence of CN units. The incorporation of CN units in 3b and 7a lowers their respective LUMO level by 220 and 350 meV compared to their corresponding CN-free counterparts 3c and 7b, suggesting an improvement of the electron-accepting strength. Polymers 3b and 7a are efficient electron acceptors suitable for photovoltaic application. The experiments indicate that 3b is a better electron acceptor when used together with M3EH-PPV, but transport properties seem to be better for 7a. With 3b, high external quantum efficiencies of up to 23\%, an open circuit voltage of up to 1.52 V, and a white light energy efficiency of 0.65\% could be realized in bilayer solar cell devices. LED-devices of configuration ITO/PEDOT:PSS/polymer/Ca/Al from 3b, 3c, 7a, and 7b showed low turn-on voltages between 2 and 2.5 V. The CN-free polymers 3c and 7b exhibit far better EL parameters than their corresponding CN containing counterparts 3b and 7a},
  language  = {en}
}
@article{KietzkeNeherKumkeetal.2004,
  author    = {Kietzke, Thomas and Neher, Dieter and Kumke, Michael Uwe and Montenegro, Rivelino V. D. and Landfester, Katharina and Scherf, Ullrich},
  title     = {A nanoparticle approach to control the phase separation in polyfluorene photovoltaic devices},
  year      = {2004},
  abstract  = {Polymer solar cell devices with nanostructured blend layers have been fabricated using single- and dual- component polymer nanospheres. Starting from an electron-donating and an electron-accepting polyfluorene derivative, PFB and F8BT, dissolved in suitable organic solvents, dispersions of solid particles with mean diameters of ca. 50 nm, containing either the pure polymer components or a mixture of PFB and F8BT in each particle, were prepared with the miniemulsion process. Photovoltaic devices based on these particles have been studied with respect to the correlation between external quantum efficiency and layer composition. It is shown that the properties of devices containing a blend of single-component PFB and F8BT particles differ significantly from those of solar cells based on blend particles, even for the same layer composition. Various factors determining the quantum efficiency in both kinds of devices are identified and discussed, taking into account the spectroscopic properties of the particles. An external quantum efficiency of ca. 4\% is measured for a device made from polymer blend nanoparticles containing PFB:F8BT at a weight ratio of 1:2 in each individual nanosphere. This is among the highest values reported so far for photovoltaic cells using this material combination},
  language  = {en}
}
@article{BagnichBasslerNeher2004,
  author    = {Bagnich, Sergey A. and Bassler, H. and Neher, Dieter},
  title     = {Sensitized phosphorescence of benzil-doped ladder-type methyl-poly(para-phenylene)},
  issn      = {0021-9606},
  year      = {2004},
  abstract  = {The delayed luminescence and phosphorescence of ladder-type methyl-poly(para-phenylene) (MeLPPP) doped with benzil at a concentration of 20\% by weight has been measured. The introduction of benzil leads to a dramatic reduction of the polymer singlet emission. At the same time, a new band with maximum at 611 nm appears, corresponding to the phosphorescence of MeLPPP. The phosphorescence decay on the short time scale is close to an exponential law with a time decay of 15 ms. This indicates that benzil can efficiently sensitize the phosphorescence of the polymer. In addition, a broad and featureless emission is observed in the delayed luminescence spectra of benzil-doped MeLPPP, which is attributed to an exciplex formed between the polymer host and the dopant. We further observe that the delayed fluorescence is enhanced by the addition of benzil. It is concluded that the delayed fluorescence of benzil-doped MeLPPP is mainly due to the annihilation of triplet excitons on the polymer. Finally, efficient triplet-triplet energy transfer from the benzil-doped polymer to the red-emitting phosphorescent dye Pt(II)octaethylporphyrin is established. (C) 2004 American Institute of Physics},
  language  = {en}
}
@article{KulikovskyNeherMecheretal.2004,
  author    = {Kulikovsky, Lazar and Neher, Dieter and Mecher, E. and Meerholz, Klaus and Horhold, H. H. and Ostroverkhova, O.},
  title     = {Photocurrent dynamics in a poly(phenylene vinylene)-based photorefractive composite},
  issn      = {1098-0121},
  year      = {2004},
  abstract  = {All parameters describing the charge carrier dynamics in a poly(phenylene vinylene)-based photorefractive (PR) composite relevant to PR grating dynamics were determined using photoconductivity studies under various illumination conditions. In particular, the values of the coefficients for trap filling and recombination of charges with ionized sensitizer molecules could be extracted independently. It is concluded that the PR growth time without preillumination is mostly determined by the competition between deep trap filling and recombination with ionized sensitizer molecules. Further, the pronounced increase in PR speed upon homogeneous preillumination (gating) as reported recently is quantitatively explained by deep trap filling},
  language  = {en}
}
@article{BommerAbrahamsonStrasseretal.2004,
  author    = {Bommer, Julian J. and Abrahamson, Norman A. and Strasser, F. O. and Pecker, Alain and Bard, Pierre-Yves and Bungum, Hilmar and Cotton, Fabrice and F{\"a}h, Donat and Sabetta, F. and Scherbaum, Frank and Studer, Jost},
  title     = {The challenge of defining upper bounds on earthquake ground motions},
  issn      = {0895-0695},
  year      = {2004},
  language  = {en}
}
@article{ZentelBehlNeheretal.2004,
  author    = {Zentel, Rudolf and Behl, Marc and Neher, Dieter and Zen, Achmad and Lucht, Sylvia},
  title     = {Nanostructured polytriarylamines : orientation layers for polyfluorene},
  issn      = {0065-7727},
  year      = {2004},
  language  = {en}
}
@article{ScherbaumCottonSmit2004,
  author    = {Scherbaum, Frank and Cotton, Fabrice and Smit, P.},
  title     = {On the use of response spectral-reference data for the selection and ranking of ground-motion models for seismic-hazard analysis in regions of moderate seismicity : the case of rock motion},
  issn      = {0037-1106},
  year      = {2004},
  abstract  = {The use of ground-motion-prediction equations to estimate ground shaking has become a very popular approach for seismic-hazard assessment, especially in the framework of a logic-tree approach. Owing to the large number of existing published ground-motion models, however, the selection and ranking of appropriate models for a particular target area often pose serious practical problems. Here we show how observed around-motion records can help to guide this process in a systematic and comprehensible way. A key element in this context is a new, likelihood based, goodness-of-fit measure that has the property not only to quantify the model fit but also to measure in some degree how well the underlying statistical model assumptions are met. By design, this measure naturally scales between 0 and 1, with a value of 0.5 for a situation in which the model perfectly matches the sample distribution both in terms of mean and standard deviation. We have used it in combination with other goodness-of-fit measures to derive a simple classification scheme to quantify how well a candidate ground-rnotion-prediction equation models a particular set of observed-response spectra. This scheme is demonstrated to perform well in recognizing a number of popular ground-motion models from their rock-site- recording, subsets. This indicates its potential for aiding the assignment of logic-tree weights in a consistent and reproducible way. We have applied our scheme to the border region of France, Germany, and Switzerland where the M-w 4.8 St. Die earthquake of 22 February 2003 in eastern France recently provided a small set of observed-response spectra. These records are best modeled by the ground-motion-prediction equation of Berge-Thierry et al. (2003), which is based on the analysis of predominantly European data. The fact that the Swiss model of Bay et al. (2003) is not able to model the observed records in an acceptable way may indicate general problems arising from the use of weak-motion data for strong-motion prediction},
  language  = {en}
}
@article{ScherbaumSchmedesCotton2004,
  author    = {Scherbaum, Frank and Schmedes, J. and Cotton, Fabrice},
  title     = {On the conversion of source-to-site distance measures for extended earthquake source models},
  issn      = {0037-1106},
  year      = {2004},
  abstract  = {One of the major challenges in engineering seismology is the reliable prediction of site-specific ground motion for particular earthquakes, observed at specific distances. For larger events, a special problem arises, at short distances, with the source-to-site distance measure, because distance metrics based on a point-source model are no longer appropriate. As a consequence, different attenuation relations differ in the distance metric that they use. In addition to being a source of confusion, this causes problems to quantitatively compare or combine different ground- motion models; for example, in the context of Probabilistic Seismic Hazard Assessment, in cases where ground-motion models with different distance metrics occupy neighboring branches of a logic tree. In such a situation, very crude assumptions about source sizes and orientations often have to be used to be able to derive an estimate of the particular metric required. Even if this solves the problem of providing a number to put into the attenuation relation, a serious problem remains. When converting distance measures, the corresponding uncertainties map onto the estimated ground motions according to the laws of error propagation. To make matters worse, conversion of distance metrics can cause the uncertainties of the adapted ground-motion model to become magnitude and distance dependent, even if they are not in the original relation. To be able to treat this problem quantitatively, the variability increase caused by the distance metric conversion has to be quantified. For this purpose, we have used well established scaling laws to determine explicit distance conversion relations using regression analysis on simulated data. We demonstrate that, for all practical purposes, most popular distance metrics can be related to the Joyner-Boore distance using models based on gamma distributions to express the shape of some "residual function." The functional forms are magnitude and distance dependent and are expressed as polynomials. We compare the performance of these relations with manually derived individual distance estimates for the Landers, the Imperial Valley, and the Chi-Chi earthquakes},
  language  = {en}
}
@article{StillerKarageorgievGeueetal.2004,
  author    = {Stiller, Burkhard and Karageorgiev, Peter and Geue, Thomas and Morawetz, Knut and Saphiannikova, Marina and Mechau, Norman and Neher, Dieter},
  title     = {Optically induced mass transport studied by scanning near-field optical- and atomic force microscopy},
  issn      = {0204-3467},
  year      = {2004},
  abstract  = {Some functionalised thin organic films show a very unusual property, namely the light induced material transport. This effect enables to generate three-dimensional structures on surfaces of azobenzene containing films only caused by special optical excitation. The physical mechanisms underlying this phenomenon have not yet been fully understood, and in addition, the dimensions of structures created in that way are macroscopic because of the optical techniques and the wavelength of the used light. In order to gain deeper insight into the physical fundamentals of this phenomenon and to open possibilities for applications it is necessary to create and study structures not only in a macroscopic but also in nanometer range. We first report about experiments to generate optically induced nano structures even down to 100 nm size. The optical stimulation was therefore made by a Scanning Near-field Optical Microscope (SNOM). Secondly, physical conditions inside optically generated surface relief gratings were studied by measuring mechanical properties with high lateral resolution via pulse force mode and force distance curves of an AFM},
  language  = {en}
}
@article{YangNeher2004,
  author    = {Yang, X. H. and Neher, Dieter},
  title     = {Polymer electrophosphorescence devices with high power conversion efficiencies},
  issn      = {0003-6951},
  year      = {2004},
  abstract  = {We demonstrate efficient single-layer polymer phosphorescent light-emitting devices based on a green-emitting iridium complex and a polymer host co-doped with electron-transporting and hole-transporting molecules. These devices can be operated at relatively low voltages, resulting in a power conversion efficiency of up to 24 lm/W at luminous efficiencies exceeding 30 cd/A. The overall performances of these devices suggest that efficient electrophosphorescent devices with acceptable operating voltages can be achieved in very simple device structures fabricated by spin coating. (C) 2004 American Institute of Physics},
  language  = {en}
}
@article{YangNeherHerteletal.2004,
  author    = {Yang, X. H. and Neher, Dieter and Hertel, D. and Daubler, T. K.},
  title     = {Highly efficient single-layer polymer electrophosphorescent devices},
  issn      = {0935-9648},
  year      = {2004},
  abstract  = {A commercially available Ir complex has been employed for the preparation of highly efficient (see Figure) single-layer phosphorescent polymer light,emitting diodes by use of appropriate thermal treatment and proper adjustment of the layer composition. These devices exhibit essentially no dependence of the driving field on the concentration of the Ir complex, suggesting that the build-up of space-charge in the layer is insignificant},
  language  = {en}
}
@article{HeydenreichKochKovacsetal.2004,
  author    = {Heydenreich, Matthias and Koch, Andreas and Kovacs, J. and Toth, G. and Kleinpeter, Erich},
  title     = {Electronic influences on (3)J(C,H) coupling constants via -S-, -S(O)- and -SO2--: their determination, calculation and comparison of detection methods},
  issn      = {0749-1581},
  year      = {2004},
  abstract  = {(3)J(C,H) coupling constants via a sulfur atom in two series of compounds, both including a sulfide, a sulfoxide and a sulfone, were detected experimentally and calculated by quantum mechanical methods. In the first series (1-3) the coupling between a hydrogen, bonded to an Sp(3) carbon, and an Sp(2) carbon is treated; the second series (4- 6) deals with the coupling between a hydrogen, bonded to an Sp3 carbon, and an Sp3 carbon. Different pulse sequences (broadband HMBC, SelJres, 1D HSQMBC, J-HMBC-2, selective J-resolved long-range experiment and IMPEACH-MBC) proved to be useful in determining the long-range (3)J(C,H) coupling constants. However, the dynamic behaviour of two of the compounds (4 and 6) led to weighted averages of the two coupling constants expected (concerning equatorial and axial positions of the corresponding hydrogens). DFT calculations proved to be useful to calculate not only the (3)J(C,H) coupling constants but also the different contributions of FC, PSO, DSO and SD terms; the calculation of the Fermi contact term (FC) was found to be sufficient for the correct estimation of (3)J(C,H) coupling constants. Copyright (C) 2004 John Wiley Sons, Ltd},
  language  = {en}
}
@article{HeydenreichWolfWolleretal.2004,
  author    = {Heydenreich, Matthias and Wolf, G. and Woller, Jochen and Kleinpeter, Erich},
  title     = {Restricted rotation of the amino group and ring inversion in highly substituted anilines. A dynamic NMR and computational study},
  issn      = {0040-4020},
  year      = {2004},
  abstract  = {The reaction of cyclic ylidene malononitriles with acetylene (di)carboxylic acid esters led to the production of nine bicyclic systems incorporating highly substituted (5/6) anilines. The free energy of activation (DeltaG(\#)) for the restricted rotation about the aniline-NH2 bond was experimentally measured in each case and a correlation was evident between the increase in steric strain in the ground state, the electron withdrawing capabilities of the ring substituents, and a reduction in the rotational barrier. For four of the compounds, the slow ring interconversion (chairreversible arrowchair) for the annelated saturated seven-membered ring that formed part of the bicyclic system was also evident. In these four compounds, both dynamic processes were also studied theoretically using ab initio methods whilst the ring interconversion was additionally studied using molecular dynamic simulations. The interconversion between the two stable chair forms was deemed to occur via a conformation series consisting of chairreversible arrowboatreversible arrowtwist-boatreversible arrowboatreversible arrowchair. (C) 2004 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{KleinpeterKlod2004,
  author    = {Kleinpeter, Erich and Klod, Sabrina},
  title     = {Separation of anisotropic and steric substituent effects - nuclear chemical shielding analysis of H-4 and C-4 in phenanthrene and 11-ethynylphenanthrene},
  year      = {2004},
  abstract  = {The anisotropic effect of a proximally introduced ethynyl group on the chemical shifts of H-4 and C-4 of the phenanthrene skeleton was calculated using GIAO-HF/NICS methodology. The anisotropic effect, long considered to be the source of the considerable downfield shift of H-4 in 11-ethynylphenanthrene in comparison to the chemical shift value of the corresponding proton in phenanthrene, was determined to be only negligible in magnitude on the basis of these calculations. Partitioning of the natural chemical shieldings of H-4 and C-4 by the NCS-NBO method into various contributions from the C-C and C-H bonds present in each molecule revealed that steric compression was able to account for the large downfield shifts of both H-4 and C-4 in 11-ethynylphenanthrene relative to phenanthrene. Thus, the substituent effect is almost totally permeated by this latter interaction and not by the aforementioned process, which was previously presumed to be the sole underlying cause},
  language  = {en}
}
@article{KoetzGuentherKosmellaetal.2004,
  author    = {Koetz, Joachim and G{\"u}nther, Claudia and Kosmella, Sabine and Kleinpeter, Erich and Wolf, Gunter},
  title     = {Polyelectrolyte induced structural changes in the isotropic phase of the system sulfobetaine/pentanol/toluene/ water},
  year      = {2004},
  language  = {en}
}
@article{TewsBlaumJeltsch2004,
  author    = {Tews, J{\"o}rg and Blaum, Niels and Jeltsch, Florian},
  title     = {Structural and animal species diversity in arid and semi-arid savannas of the southern Kalahari},
  year      = {2004},
  language  = {en}
}
@article{KleinpeterKlodRudorf2004,
  author    = {Kleinpeter, Erich and Klod, Sabrina and Rudorf, Wolf-Dieter},
  title     = {Electronic state of push-pull alkenes : an experimental dynamic NMR and theoretical ab initio MO study},
  year      = {2004},
  abstract  = {The H-1 and C-13 NMR spectra of a number of push-pull alkenes were recorded and the C-13 chemical shifts calculated employing the GIAO perturbation method. Of the various levels of theory tried, MP2 calculations with a triple- zeta-valence basis set were found to be the most effective for providing reliable results. The effect of the solvent was also considered but only by single-point calculations. Generally, the agreement between the experimental and theoretically calculated C-13 chemical shifts was good with only the carbons of the carbonyl, thiocarbonyl, and cyano groups deviating significantly. The substituents on the different sides of the central C=C partial double bond were classified qualitatively with respect to their donor (S,S < S,N < N,N) and acceptor properties (CdropN < C=O < C=S) and according to the ring size on the donor side (6 < 7 < 5). The geometries of both the ground (GS) and transition states (TS) of the restricted rotation about the central C=C partial double bond were also calculated at the HF and MP2 levels of theory and the free energy differences compared with the barriers to rotation determined experimentally by dynamic NMR spectroscopy. Structural differences between the various push-pull alkenes were reproduced well, but the barriers to rotation were generally overestimated theoretically. Nevertheless, by correlating the barriers to rotation and the length of the central C=C partial double bonds, the push-pull alkenes could be classified with respect to the amount of hydrogen bonding present, the extent of donor-acceptor interactions (the push-pull effect), and the level of steric hindrance within the molecules. Finally, by means of NBO analysis of a set of model push-pull alkenes (acceptors: - CdropN, -CH=O, and -CH=S; donors: S, O, and NH), the occupation numbers of the bonding pi orbitals of the central C=C partial double bond were shown to quantitatively describe the acceptor powers of the substituents and the corresponding occupation numbers of the antibonding pi* orbital the donor powers of the substituents. Thus, for the first time an estimation of both the acceptor and the donor properties of the substituents attached to the push-pull double bond have been separately quantified. Furthermore, both the balance between strong donor/weak acceptor substituents (and vice versa) and the additional influences on the barriers to rotation (hydrogen bonding and steric hindrance in the GSs and TSs) could be differentiated},
  language  = {en}
}
@article{KleinpeterSeidl2004,
  author    = {Kleinpeter, Erich and Seidl, Peter Rudolf},
  title     = {The gamma- and the delta-effects in C-13 NMR spectroscopy in terms of nuclear chemical shielding (NCS) analysis},
  year      = {2004},
  abstract  = {Carbon-13 NMR is widely used in the determination of the stereochemistry of organic compounds. Changes in chemical shifts caused by interactions of groups that are close in space normally result in shielding of the carbon and deshielding of the hydrogen nuclei that are involved. This is not always the case, however, and further work on the origin of these effects would be desirable. Early applications of theoretical methods to the study of NMR shielding parameters were not particularly successful, but in recent years, the calculation of NMR shielding parameters by theoretical methods has developed into a useful and popular tool for structural studies by NMR. A promising approach to the problem of distinguishing and evaluating stereochemical influences on carbon and hydrogen chemical shifts is provided by natural chemical shielding (NCS) analysis. This method allows a partitioning of theoretical NMR shieldings into magnetic contributions from bonds and lone pairs of the molecule using the natural bond orbital (NBO) method. In order to investigate the origins of steric effects, we employed the NCS analysis to axial/equatorial-Me-cyclohexane, norbornane and exo/endo-Me-norbornane, in addition to n-pentane in the anti, gauche and g(P) g(M) conformations. Our results indicate that distortions in molecular structure due to steric effects can result in bond stretching or compression or in angular distortions. Changes in bond lengths result in the predictable shielding or deshielding of the nuclei that are involved. Where the molecular framework may be distorted to alleviate strain, chemical shifts appear to reflect changes in angles. Copyright (C) 2004 John Wiley Sons, Ltd},
  language  = {en}
}
@article{HolzbergerHoldtKleinpeter2004,
  author    = {Holzberger, Anja and Holdt, Hans-J{\"u}rgen and Kleinpeter, Erich},
  title     = {Conformational analysis of mixed oxathia crown ethers and their complexational ability towards Ag(I) and Pd(II) : an experimental solution NMR and theoretical molecular modelling study},
  issn      = {1477-0520},
  year      = {2004},
  abstract  = {Both the conformation and flexibility of four mixed oxathia crown ethers and their Ag(I) and Pd(II) complexes were studied by H-1 NMR (delta, J, NOE, T-1), C-13 NMR, dynamic 1H NMR spectroscopy and molecular modelling. The stoichiometry and stability constants of the complexes were determined from corresponding Job's plots in the case of Ag(I) complexes as the interchange between free and complexed states was fast on the NMR timescale; interchange for the Pd(II) complexes was sufficiently slow such that distinct sub-spectra were observable for the free and complexed states. In all cases where complexation was observed, 1 : 1 complexes were formed. Global minima structures determined from the modelling studies were analysed with respect to the barriers to ring interconversion, the flexibility of the species in solution and the preferred complexation of Ag(I) and Pd(II) to the sulfur atoms of the crown ethers},
  language  = {en}
}
@article{KleinpeterKlod2004,
  author    = {Kleinpeter, Erich and Klod, Sabrina},
  title     = {Ab initio calculation of the anisotropic/ring current effects of amino acid residues to locate the position of substrates in the binding site of enzymes},
  year      = {2004},
  abstract  = {The ring current effects of aromatic moieties and the anisotropic effects of the C=O and C-X (X = C, N, S) bonds and of the NH=C(NH2)-NH- moiety in the side chains of amino acid residues of proteins were ab initio calculated based on nuclear independent chemical shieldings as employed by P.v.R. Schleyer. Hereby, quantitative information about the spatial extension, sign and scope of the corresponding ring current/anisotropic effects was obtained and they were visualized as iso-chemical-shielding-surfaces. Examining this quantitative information compared with experimental NMR chemical shifts, the role of the corresponding amino acid residues in binding substrates in the binding site of enzymes was studied. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{HolzbergerKleinpeter2004,
  author    = {Holzberger, Anja and Kleinpeter, Erich},
  title     = {Solution structure of the palladium(II) complex of 1,4,7,10-tetrathiacyclododec-2-ene-2,3-dicarbonitrile},
  issn      = {0749-1581},
  year      = {2004},
  abstract  = {The solution structure of the Pd(II) complex of mn-12-S-4 was studied in detail by NMR spectroscopy. The stoichiometry of the complex was determined by H-1 NMR titration experiments. (3)J(H,H) coupling constants were extracted from the 2D J-resolved NMR spectrum of the complex providing information concerning the S-C-C-S torsional angles. Further conclusions about the conformation of [Pd(mn-12-S-4)](BF4)(2) were drawn from experimental NOES. The results of the NMR study were corroborated by molecular modelling. Copyright (C) 2004 John Wiley Sons, Ltd},
  language  = {en}
}
@article{HolzbergerHoldtKleinpeter2004,
  author    = {Holzberger, Anja and Holdt, H. N. and Kleinpeter, Erich},
  title     = {NMR spectroscopic and molecular modelling study of the solution structure and the complexational behavior of maleonitrile tetrathia crown ethers with silver(I)},
  year      = {2004},
  abstract  = {The flexibility and complex formation of two maleonitrile tetrathia crown ethers were studied in solution using H-1 and C-13 NMR spectroscopy and molecular modelling. Both the stoichiometry and the stability of the complexes that these crown ethers form with Ag(I) were determined by NMR titration measurements. Spin-lattice relaxation time measurements provided information concerning the donor atoms involved in complex formation and also the intramolecular mobility of the free and complexed ligands. Molecular modelling was also used to gain further insight into the conformational space of the free ligands and their silver(I) complexes. Copyright (C) 2004 John Wiley Sons, Ltd},
  language  = {en}
}
@article{KochMikhovaKleinpeter2004,
  author    = {Koch, Andreas and Mikhova, Bozhana and Kleinpeter, Erich},
  title     = {Ab initio MP2/GIAO/NBO study of the delta-syn-axial effect in C-13 NMR spectroscopy},
  issn      = {0022-2860},
  year      = {2004},
  abstract  = {The C-13 chemical shifts of 20 rigid bicyclic compounds have been calculated with ab initio HF and MP2 methods. The calculations showed very good reproducibility of the experimental values. The molecular orbital interactions in the rigid, nearly planar delta-syn-axial fragments in the isomeric groups of norbornane derivatives 1.x-4.x were studied in detail and were employed to explain the deshielding delta-syn-axial effect in C-13 NMR spectroscopy. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{SzatmariMartinekLazaretal.2004,
  author    = {Szatmari, Istvan and Martinek, T. A. and Lazar, L. and Koch, Andreas and Kleinpeter, Erich and Neuvonen, Kari and Fulop, Ferenc},
  title     = {Stereoelectronic effects in ring-chain tautomerism of 1,3-diarylnaphth[1,2-e][1,3]oxazines and 3-alkyl-1- arylnaphth[1,2-e][1,3]oxazines},
  issn      = {0022-3263},
  year      = {2004},
  abstract  = {The disubstitution effects of X and Y in 1-(Y-phenyl)-3-(X-phenyl)-2,3-dihydro-1H-naphth[1,2-e][1,3]oxazines on the ring-chain tautomerism, the delocalization of the nitrogen lone pair (anomeric effect), and the C-13 NMR chemical shifts were analyzed by using multiple linear regression analysis. Study of the three-component equilibrium B reversible arrow A reversible arrow C revealed that the chain reversible arrow trans (A reversible arrow B) equilibrium constants are significantly influenced by the inductive effect (sigma(F)) of substituent Y on the 1-phenyl ring. In contrast, no significant substituent dependence on Y was observed for the chain reversible arrow cis (A reversible arrow C) equilibrium. There was an analogous dependence for the epimerization (C reversible arrow B) constants of 1-(Y-phenyl)-3- alkyl-2,3-dihydro-1H-naphth[1,2-e] [1,3]oxazines. With these model compounds, significant overlapping energies of the nitrogen lone pair was observed by NBO analysis in the trans forms B (to sigma*(C1-C1'), sigma*(C1-C10b), and sigma*(C3-O4)) and in the cis forms C (to sigma*(C1-H), sigma*(C1-C10b), and sigma*(C3-O4)). The effects of disubstitution revealed some characteristic differences between the cis and trans isomers. However, the results do not suggest that the anomeric effect predominates in the preponderance of the trans over the cis isomer. When the C-13 chemical shift changes induced Y by substituents X and Y (SCS) were subjected to multiple linear regression analysis, negative rho(F)(Y) and rho(F)(X) values were observed at C-1 and C-3 for both the cis and trans isomers. In contrast, the positive rho(R)(Y) values at C-1 and the negative rho(R)(X) values at C-3 observed indicated the contribution of resonance structures f (rho(R) > 0) and g (rho(R) < 0), respectively. The classical double bond-no-bond resonance structures proved useful in explaining the substituent sensitivities of the donation energies and the behavior of the SCS values},
  language  = {en}
}
@article{HausmannKassKlodetal.2004,
  author    = {Hausmann, J. and Kass, S. and Klod, Sabrina and Kleinpeter, Erich and Kersting, Berthold},
  title     = {Binucleating aza-sulfonate and aza-sulfinate macrocycles : Synthesis and coordination chemistry},
  issn      = {1434-1948},
  year      = {2004},
  abstract  = {The preparation and ligating properties of S-oxygenated derivatives of a macrobinucleating hexaazadithiophenolate macrocycle H2L1 of the Robson type towards nickel(II) and zinc(II) ions are reported. Nickel complexes of the hexaazadiphenylsulfonate ligand (L-2)(2-)[(L-2)Ni-2(II)(mu-L)](+)(L = m-Cl-OBz(-) (3), Cl- (4) and OAc- (6)] are readily obtained in high yields by oxidation of the respective [(L-1)Ni-2(II)(mu-L)](+) parent complexes [L = m- Cl-OBz- (2), Cl- (1), OAc- (5)] with meta-chloroperoxybenzoic acid or hydrogen peroxide. Decomposition of the sulfonate complexes gives the free macrocycle H2L2 which, upon treatment with Zn(OAc)(2)(.)2H(2)O, produces the diamagnetic zinc complex [(L-2)Z(2)(II)(OAc)](+) (8). A dinuclear Cu-II complex of the hexaazadisulfinate derivative (L-3')(2-), [(L-3)CU2II](2+) (9), is formed rather unexpectedly by air oxidation of (L-1)(2-) in the presence of Cu-I. The crystal- structure determinations of the perchlorate or tetraphenylborate salts of 2, 3, and 4 show that the new ligands support the formation of binuclear complexes with bowl-shaped, calixarene-like binding cavities. NMR spectroscopic studies of 8 show that the complexes retain their solid-state structures in solution. A crystal-structure determination of 9 reveals two five-coordinate Cu-II ions bridged by the two sulfinate functions of (L-3)(2-)},
  language  = {en}
}
@article{MiklosKanizsaiThomasetal.2004,
  author    = {Miklos, F. and Kanizsai, I. and Thomas, Steffen and Kleinpeter, Erich and Sillanpaa, R. and Stajer, G.},
  title     = {Preparation and structure of diexo-oxanorbornane-fused 1,3-heterocycles},
  issn      = {0385-5414},
  year      = {2004},
  abstract  = {Via the reaction of diexo-oxanorbornanedicarboxylic anhydride with toluene, the diexo-aroylcarboxylic acid (3a) was prepared, which exists partly as the tautomeric lactol (3b). With bifunctional reagents, 3a yields fused heterocycles containing three-six rings. Thus, alkylenediamines result in imidazole- and 1,3-diazepine-fused oxygen- bridged isoindolones (6a,b), alkanolamines form the oxazole- and 1,3-oxazine-fused oxanorbornene derivatives (7a-c), and o-phenylenediamine undergoes cyclization to furnish the condensed benzimidazole (8). The reaction of 3a with diexo- aminonorbornanecarbohydrazide yields a pyrimidopyridazine containing six condensed rings (9). In a similar reaction with diendo-aminonorbornenecarbohydrazide, cyclopentadiene cleaves off to give the tricyclic retro Diels-Alder product (10). The structures, and particulary the configurations at the oxanorbornane ring systems and the position of the aryl substituent, were established by means of 1D- and 2D-NMR spectroscopy and, for 3b and 7c, also by X-Ray measurements},
  language  = {en}
}
@article{TaddeiKleinpeter2004,
  author    = {Taddei, F. and Kleinpeter, Erich},
  title     = {The anomeric effect in substituted cyclohexanes : I. The role of hyperconjugative interactions and steric effect in monosubstituted cyclohexanes},
  issn      = {0166-1280},
  year      = {2004},
  abstract  = {The relative energy of conformers, DeltaE, of monosubstituted cyclohexanes with OR (R = Me, Et, i-Pr and t-Bu) and R substituents (R = Me, Et, i-Pr and t-Bu) was calculated with MO ab initio theory at RHF, MP2 and QCISD levels with the 6-311G* and 6-311 + G* basis sets. A selected group of delocalizing interactions were calculated with the natural bond orbital method in order to quantify the hyperconjugative contribution, DeltaE(hyp.), to the relative stability of conformers. From the calculated values of DeltaE and DeltaE(hyp.) an estimate of the differential steric effect, DeltaE(ster.), of substituents in cyclohexane was obtained. The values of DeltaE(hyp), and DeltaE(ster.) show that they have a similar magnitude for OR substituents, while for R substituents the values of are greater. The shift in the conformational equilibrium towards the axial conformer, the so-called anomeric effect, takes place when, within a series of substituents, hyperconjugative interactions and steric interactions balance in favour of the stability of this conformer. (C) 2004 Elsevier B.V. All rights reserved},
  language  = {en}
}
@article{StarkeSarodnickOvcharenkoetal.2004,
  author    = {Starke, I. and Sarodnick, Gerhard and Ovcharenko, V. V. and Pihlaja, Kalevi and Kleinpeter, Erich},
  title     = {Quinoxalines : Part 13: Synthesis and mass spectrometric study of aryloxymethylquinoxalines and benzo[b]furylquinoxalines},
  issn      = {0040-4020},
  year      = {2004},
  abstract  = {A series of new aryloxymethylquinoxalines, benzo[b]- and naphtho[2,1-b] fury] quinoxalines, possessing potential biological activity, was prepared, characterized by IR and NMR spectroscopy and their electron ionization (EI) mass spectra studied in detail. The aryloxymethylquinoxalines were obtained by reacting halogenomethylquinoxalines with bifunctional O-nucleophiles. The benzo[b]furylquinoxalines and naphtho[2, I -b]furylquinoxalines were prepared via two routes, which differed in the order of the two cyclization steps involved in the syntheses. The composition of the ions obtained by El mass spectrometry were determined by accurate mass measurements and the fragmentation pathways clarified by B/E linked scans and collision induced dissociation. The mass spectrometric behaviour of the compounds studied as to the possible loss of OH' radicals proved to be very characteristic. (C) 2004 Elsevier Ltd. All rights reserved},
  language  = {en}
}
@article{QuZhangGrimsdaleetal.2004,
  author    = {Qu, J. Q. and Zhang, J. Y. and Grimsdale, A. C. and Mullen, K. and Jaiser, Frank and Yang, X. H. and Neher, Dieter},
  title     = {Dendronized perylene diimide emitters : Synthesis, luminescence, and electron and energy transfer studies},
  issn      = {0024-9297},
  year      = {2004},
  abstract  = {Aggregation of chromophores in the solid state commonly causes undesirable red shifts in the emission spectra and/or emission quenching. To overcome this problem, we have prepared soluble perylenetetracarboxidiimide dyes in which the chromophores are effectively shielded by polyphenylene dendrimers attached in the bay positions. Models show that attachment of the shielding units in the bay position should provide more efficient shielding than attaching them via the imide moieties. The dendrimers possess excellent film-forming properties due to alkyl substituents on their peripheries. The lack of a red shift in emission upon going from solution to the solid state indicates the dendrons suppress interaction of the emissive cores, leading to pure red-orange emission. Single-layer LEDs produce red-orange emission with relatively low efficiency especially for the higher generation dendrons, which is attributed to poor charge conduction. LEDs using blends of the dendrimers and the undendronized dye as a model compound in PVK have been investigated, and a model to extract relative charge injection rates through the dendritic scaffold from the spectral contributions in the EL spectra is developed},
  language  = {en}
}
@article{ZenPflaumHirschmannetal.2004,
  author    = {Zen, Achmad and Pflaum, J. and Hirschmann, S. and Zhuang, W. and Jaiser, Frank and Asawapirom, Udom and Rabe, J. P. and Scherf, Ullrich and Neher, Dieter},
  title     = {Effect of molecular weight and annealing of poly (3-hexylthiophene)s on the performance of organic field-effect transistors},
  year      = {2004},
  abstract  = {The optical, structural, and electrical properties of thin layers made from poly(3-hexylthiophene) (P3HT) samples of different molecular weights are presented. As reported in a previous paper by Kline et al., Adv. Mater 2003, 15, 1519, the mobilities of these layers are a strong function of the molecular weight, with the largest mobility found for the largest molecular weight. Atomic force microscopy studies reveal a complex polycrystalline morphology which changes considerably upon annealing. X-ray studies show the occurrence of a layered phase for all P3HT fractions, especially after annealing at 1.50 degreesC . However, there is no clear correlation between the differences in the transport properties and the data from structural investigations. In order to reveal the processes limiting the mobility in these layers, the transistor properties were investigated as a function of temperature. The mobility decreases continuously with increasing temperatures; with the same trend pronounced thermochromic effects of the P3HT films occur. Apparently, the polymer chains adopt a more twisted, disordered conformation at higher temperatures, leading to interchain transport barriers. We conclude that the backbone conformation of the majority of the bulk material rather than the crystallinity of the layer is the most crucial parameter controlling the charge transport in these P3HT layers. This interpretation is supported by the significant blue-shift of the solid-state absorption spectra with decreasing molecular weight, which is indicative of a larger distortion of the P3HT backbone in the low-molecular weight P3HT layers},
  language  = {en}
}
@article{YangJaiserNeheretal.2004,
  author    = {Yang, Xiao Hui and Jaiser, Frank and Neher, Dieter and Lawson, PaDreyia V. and Br{\´e}das, Jean-Luc and Zojer, Egbert and G{\"u}ntner, Roland and Scanduicci de Freitas, Patricia and Forster, Michael and Scherf, Ullrich},
  title     = {Suppression of the keto-emission in polyfluorene light-emitting diodes : Experiments and models},
  issn      = {1616-301X},
  year      = {2004},
  abstract  = {The spectral characteristics of polyfluorene (PF)-based light-emitting diodes (LEDs) containing a defined low concentration of either keto-defects or of the polymer poly(9.9-octylfuorene-co-benzothiadiazole) (F8BT) are preseneted. Both types of blend layers were tested in different device configurations with respect to the relative and absolute intensities of green blue emission components. It is shown that blending hole-transporting molecules into the emission layer at low concentration or incorporation of a suitable hole-transport layer reduces the green emission contribution in the electroluminescence (EL) spectrum of the PF:F8BT blend, which is similar to what is observed for the keto- containing PF layer. We conclude that the keto-defects in PF homopolymer layers mainly constitute weakly emissive electron traps, in agreement with the results of quantum-mechanical calculations},
  language  = {en}
}
@article{ScheichNiesenSeckleretal.2004,
  author    = {Scheich, Christoph and Niesen, F. H. and Seckler, Robert and Bussow, K.},
  title     = {An automated in vitro protein folding screen applied to a human dynactin subunit},
  issn      = {0961-8368},
  year      = {2004},
  abstract  = {The preparation of proteins for structural and functional analysis using the Escherichia coli expression system is often hampered by the formation of insoluble intracellular protein aggregates (inclusion bodies). Transferring those proteins into their native states by in vitro protein folding requires screening for the best buffer conditions and suitable additives. However, it is difficult to assess the success of such a screen if no biological assay is available. We established a fully automated folding screen and a system to detect folded protein that is based on analytical hydrophobic interaction chromatography and tryptophan fluorescence spectroscopy. The system was evaluated with two model enzymes (carbonic anhydrase II and malate dehydrogenase), and was successfully applied to the folding of the p22 subunit of human dynactin, which is expressed in inclusion bodies in E. coli. The described screen allows for high-throughput folding analysis of inclusion body proteins for structural and functional analyses},
  language  = {en}
}
@article{KlieglGrabnerRolfsetal.2004,
  author    = {Kliegl, Reinhold and Grabner, Ellen and Rolfs, Martin and Engbert, Ralf},
  title     = {Length, frequency, and predictability effects of words on eye movements in reading},
  year      = {2004},
  language  = {en}
}
@article{OberauerKliegl2004,
  author    = {Oberauer, Klaus and Kliegl, Reinhold},
  title     = {Simultaneous cognitive operations in working memory after dual-task practice},
  issn      = {0096-1523},
  year      = {2004},
  abstract  = {The authors tested the hypothesis that with adequate practice, people can execute 2 cognitive operations in working memory simultaneously. In Experiment 1, 6 students practiced updating 2 items in working memory through 2 sequences of operations (1 numerical, 1 spatial). In different blocks, imperative stimuli for the 2 sequences of operations were presented either simultaneously or sequentially. Initially, most participants experienced substantial dual-task costs. After 24 sessions of practice, operation latencies for simultaneous presentation were equal to the maximum of times for the 2 operations in the sequential condition, suggesting perfect timesharing. Experiment 2 showed that a reduction of dual-task costs requires practice on the combination of the 2 updating tasks, not just practice on each individual task. Hence, the reduction of dual-task costs cannot be explained by shortening or automatization of individual operations},
  language  = {en}
}
@article{Engbert2004,
  author    = {Engbert, Ralf},
  title     = {Microsaccades keep the eyes' balance during fixation},
  year      = {2004},
  abstract  = {During fixation of a stationary target, small involuntary eye movements exhibit an erratic trajectory-a random walk. Two types of these fixational eye movements are drift and microsaccades (small-amplitude saccades). We investigated fixational eye movements and binocular coordination using a statistical analysis that had previously been applied to human posture control. This random-walk analysis uncovered two different time scales in fixational eye movements and identified specific functions for microsaccades. On a short time scale, microsaccades enhanced perception by increasing fixation errors. On a long time scale, microsaccades reduced fixation errors and binocular disparity (relative to pure drift movements). Thus, our findings clarify the role of oculomotor processes during fixation},
  language  = {en}
}
@article{EngbertKlieglLongtin2004,
  author    = {Engbert, Ralf and Kliegl, Reinhold and Longtin, Andre},
  title     = {Complexity of eye movements in reading},
  year      = {2004},
  abstract  = {During reading, our eyes perform complicated sequences of fixations on words. Stochastic models of eye movement control suggest that this seemingly erratic behaviour can be attributed to noise in the oculomotor system and random fluctuations in lexical processing. Here, we present a qualitative analysis of a recently published dynamical model [Engbert et al., 2002] and propose that deterministic nonlinear control accounts for much of the observed complexity of eye movement patterns during reading. Based on a symbolic coding technique we analyze robust statistical features of simulated fixation sequences},
  language  = {en}
}
@article{RolfsEngbertKliegl2004,
  author    = {Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold},
  title     = {Microsaccade orientation supports attentional enhancement opposite to a peripheral cue},
  year      = {2004},
  language  = {en}
}