@article{KleinRosenberger2018, author = {Klein, Markus and Rosenberger, Elke}, title = {Tunneling for a class of difference operators}, series = {Annales Henri Poincar{\´e} : a journal of theoretical and mathematical physics}, volume = {19}, journal = {Annales Henri Poincar{\´e} : a journal of theoretical and mathematical physics}, number = {11}, publisher = {Springer International Publishing}, address = {Cham}, issn = {1424-0637}, doi = {10.1007/s00023-018-0732-0}, pages = {3511 -- 3559}, year = {2018}, abstract = {We analyze a general class of difference operators Hε=Tε+Vε on ℓ2((εZ)d), where Vε is a multi-well potential and ε is a small parameter. We derive full asymptotic expansions of the prefactor of the exponentially small eigenvalue splitting due to interactions between two "wells" (minima) of the potential energy, i.e., for the discrete tunneling effect. We treat both the case where there is a single minimal geodesic (with respect to the natural Finsler metric induced by the leading symbol h0(x,ξ) of Hε) connecting the two minima and the case where the minimal geodesics form an ℓ+1 dimensional manifold, ℓ≥1. These results on the tunneling problem are as sharp as the classical results for the Schr{\"o}dinger operator in Helffer and Sj{\"o}strand (Commun PDE 9:337-408, 1984). Technically, our approach is pseudo-differential and we adapt techniques from Helffer and Sj{\"o}strand [Analyse semi-classique pour l'{\´e}quation de Harper (avec application {\`a} l'{\´e}quation de Schr{\"o}dinger avec champ magn{\´e}tique), M{\´e}moires de la S.M.F., 2 series, tome 34, pp 1-113, 1988)] and Helffer and Parisse (Ann Inst Henri Poincar{\´e} 60(2):147-187, 1994) to our discrete setting.}, language = {en} } @article{KleinRosenberger2012, author = {Klein, Markus and Rosenberger, Elke}, title = {Tunneling for a class of difference operators}, series = {ANNALES HENRI POINCARE}, volume = {13}, journal = {ANNALES HENRI POINCARE}, number = {5}, publisher = {Springer}, address = {Basel}, issn = {1424-0637}, doi = {10.1007/s00023-011-0152-x}, pages = {1231 -- 1269}, year = {2012}, abstract = {We analyze a general class of difference operators on where is a multi-well potential and is a small parameter. We decouple the wells by introducing certain Dirichlet operators on regions containing only one potential well, and we shall treat the eigenvalue problem for as a small perturbation of these comparison problems. We describe tunneling by a certain interaction matrix, similar to the analysis for the Schrodinger operator [see Helffer and Sjostrand in Commun Partial Differ Equ 9:337-408, 1984], and estimate the remainder, which is exponentially small and roughly quadratic compared with the interaction matrix.}, language = {en} } @unpublished{KleinRosenberger2012, author = {Klein, Markus and Rosenberger, Elke}, title = {Tunneling for a class of difference operators}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56989}, year = {2012}, abstract = {We analyze a general class of difference operators containing a multi-well potential and a small parameter. We decouple the wells by introducing certain Dirichlet operators on regions containing only one potential well, and we treat the eigenvalue problem as a small perturbation of these comparison problems. We describe tunneling by a certain interaction matrix similar to the analysis for the Schr{\"o}dinger operator, and estimate the remainder, which is exponentially small and roughly quadratic compared with the interaction matrix.}, language = {en} } @article{NeidhardtZagrebnov1998, author = {Neidhardt, Hagen and Zagrebnov, Valentin A.}, title = {Trotter-Kato product formula and symmetrically-normed ideals}, year = {1998}, language = {en} } @article{NeidhardtZagrebnov1999, author = {Neidhardt, Hagen and Zagrebnov, Valentin A.}, title = {Trotter-Kato product formula and operator-norm convergence}, year = {1999}, language = {en} } @article{Zagrebnov2020, author = {Zagrebnov, Valentin}, title = {Trotter product formula on Hilbert and Banach spaces for operator-norm convergence}, series = {Lectures in pure and applied mathematics}, journal = {Lectures in pure and applied mathematics}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-485-2}, issn = {2199-4951}, doi = {10.25932/publishup-47197}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-471971}, pages = {23 -- 34}, year = {2020}, language = {en} } @article{BrungsGraeter2000, author = {Brungs, Hans and Gr{\"a}ter, Joachim}, title = {Trees and Valuation Rings}, year = {2000}, language = {en} } @article{DeneckePabhapote2001, author = {Denecke, Klaus-Dieter and Pabhapote, Nittiya}, title = {Tree-recognizers and tree-hyperrecognizers}, year = {2001}, language = {en} } @article{ArwornDenecke2001, author = {Arworn, Srichan and Denecke, Klaus-Dieter}, title = {Tree Transformations defined by Hypersubstitutions}, issn = {1509 - 9415}, year = {2001}, language = {en} } @article{DeneckeLeeratanavalee2003, author = {Denecke, Klaus-Dieter and Leeratanavalee, Sorasak}, title = {Tree transformations defined by generalized hypersubstitutions}, year = {2003}, language = {en} } @unpublished{GairingHoegeleKosenkova2016, author = {Gairing, Jan and H{\"o}gele, Michael and Kosenkova, Tetiana}, title = {Transportation distances and noise sensitivity of multiplicative L{\´e}vy SDE with applications}, volume = {5}, number = {2}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, issn = {2193-6943}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-86693}, pages = {24}, year = {2016}, abstract = {This article assesses the distance between the laws of stochastic differential equations with multiplicative L{\´e}vy noise on path space in terms of their characteristics. The notion of transportation distance on the set of L{\´e}vy kernels introduced by Kosenkova and Kulik yields a natural and statistically tractable upper bound on the noise sensitivity. This extends recent results for the additive case in terms of coupling distances to the multiplicative case. The strength of this notion is shown in a statistical implementation for simulations and the example of a benchmark time series in paleoclimate.}, language = {en} } @article{GairingHoegeleKosenkova2017, author = {Gairing, Jan and H{\"o}gele, Michael and Kosenkova, Tetiana}, title = {Transportation distances and noise sensitivity of multiplicative Levy SDE with applications}, series = {Stochastic processes and their application}, volume = {128}, journal = {Stochastic processes and their application}, number = {7}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0304-4149}, doi = {10.1016/j.spa.2017.09.003}, pages = {2153 -- 2178}, year = {2017}, abstract = {This article assesses the distance between the laws of stochastic differential equations with multiplicative Levy noise on path space in terms of their characteristics. The notion of transportation distance on the set of Levy kernels introduced by Kosenkova and Kulik yields a natural and statistically tractable upper bound on the noise sensitivity. This extends recent results for the additive case in terms of coupling distances to the multiplicative case. The strength of this notion is shown in a statistical implementation for simulations and the example of a benchmark time series in paleoclimate.}, language = {en} } @article{Schulze1995, author = {Schulze, Bert-Wolfgang}, title = {Transmission algebras on singular spaces with components of different dimensions}, year = {1995}, language = {en} } @article{WichaHuisingaKloft2017, author = {Wicha, Sebastian G. and Huisinga, Wilhelm and Kloft, Charlotte}, title = {Translational pharmacometric evaluation of typical antibiotic broad-spectrum combination therapies against staphylococcus aureus exploiting in vitro information}, series = {CPT: pharmacometrics \& systems pharmacology}, volume = {6}, journal = {CPT: pharmacometrics \& systems pharmacology}, publisher = {Wiley}, address = {Hoboken}, issn = {2163-8306}, doi = {10.1002/psp4.12197}, pages = {512 -- 522}, year = {2017}, abstract = {Broad-spectrum antibiotic combination therapy is frequently applied due to increasing resistance development of infective pathogens. The objective of the present study was to evaluate two common empiric broad-spectrum combination therapies consisting of either linezolid (LZD) or vancomycin (VAN) combined with meropenem (MER) against Staphylococcus aureus (S. aureus) as the most frequent causative pathogen of severe infections. A semimechanistic pharmacokinetic-pharmacodynamic (PK-PD) model mimicking a simplified bacterial life-cycle of S. aureus was developed upon time-kill curve data to describe the effects of LZD, VAN, and MER alone and in dual combinations. The PK-PD model was successfully (i) evaluated with external data from two clinical S. aureus isolates and further drug combinations and (ii) challenged to predict common clinical PK-PD indices and breakpoints. Finally, clinical trial simulations were performed that revealed that the combination of VAN-MER might be favorable over LZD-MER due to an unfavorable antagonistic interaction between LZD and MER.}, language = {en} } @article{Schrohe1996, author = {Schrohe, Elmar}, title = {Traces on the cone algebra with asymptotics}, year = {1996}, language = {en} } @article{GrubbSchrohe2001, author = {Grubb, G. and Schrohe, Elmar}, title = {Trace expansions and the noncommutative dresidue for manifolds with boundary}, year = {2001}, language = {en} } @misc{WeisserStueblerMatheisetal.2017, author = {Weisser, Karin and St{\"u}bler, Sabine and Matheis, Walter and Huisinga, Wilhelm}, title = {Towards toxicokinetic modelling of aluminium exposure from adjuvants in medicinal products}, series = {Regulatory toxicology and pharmacology : official journal of the International Society for Regulatory Toxicology and Pharmacology}, volume = {88}, journal = {Regulatory toxicology and pharmacology : official journal of the International Society for Regulatory Toxicology and Pharmacology}, publisher = {Elsevier}, address = {San Diego}, issn = {0273-2300}, doi = {10.1016/j.yrtph.2017.02.018}, pages = {310 -- 321}, year = {2017}, abstract = {As a potentially toxic agent on nervous system and bone, the safety of aluminium exposure from adjuvants in vaccines and subcutaneous immune therapy (SCIT) products has to be continuously reevaluated, especially regarding concomitant administrations. For this purpose, knowledge on absorption and disposition of aluminium in plasma and tissues is essential. Pharmacokinetic data after vaccination in humans, however, are not available, and for methodological and ethical reasons difficult to obtain. To overcome these limitations, we discuss the possibility of an in vitro-in silico approach combining a toxicokinetic model for aluminium disposition with biorelevant kinetic absorption parameters from adjuvants. We critically review available kinetic aluminium-26 data for model building and, on the basis of a reparameterized toxicokinetic model (Nolte et al., 2001), we identify main modelling gaps. The potential of in vitro dissolution experiments for the prediction of intramuscular absorption kinetics of aluminium after vaccination is explored. It becomes apparent that there is need for detailed in vitro dissolution and in vivo absorption data to establish an in vitro-in vivo correlation (IVIVC) for aluminium adjuvants. We conclude that a combination of new experimental data and further refinement of the Nolte model has the potential to fill a gap in aluminium risk assessment. (C) 2017 Elsevier Inc. All rights reserved.}, language = {en} } @article{NeidhardtZagrebnov1996, author = {Neidhardt, Hagen and Zagrebnov, Valentin A.}, title = {Towards the right Hamiltonians for singular perturbations via regularization and extension theory}, year = {1996}, language = {en} } @article{AcevedoReichCubasch2016, author = {Acevedo, Walter and Reich, Sebastian and Cubasch, Ulrich}, title = {Towards the assimilation of tree-ring-width records using ensemble Kalman filtering techniques}, series = {Climate dynamics : observational, theoretical and computational research on the climate system}, volume = {46}, journal = {Climate dynamics : observational, theoretical and computational research on the climate system}, publisher = {Springer}, address = {New York}, issn = {0930-7575}, doi = {10.1007/s00382-015-2683-1}, pages = {1909 -- 1920}, year = {2016}, abstract = {This paper investigates the applicability of the Vaganov-Shashkin-Lite (VSL) forward model for tree-ring-width chronologies as observation operator within a proxy data assimilation (DA) setting. Based on the principle of limiting factors, VSL combines temperature and moisture time series in a nonlinear fashion to obtain simulated TRW chronologies. When used as observation operator, this modelling approach implies three compounding, challenging features: (1) time averaging, (2) "switching recording" of 2 variables and (3) bounded response windows leading to "thresholded response". We generate pseudo-TRW observations from a chaotic 2-scale dynamical system, used as a cartoon of the atmosphere-land system, and attempt to assimilate them via ensemble Kalman filtering techniques. Results within our simplified setting reveal that VSL's nonlinearities may lead to considerable loss of assimilation skill, as compared to the utilization of a time-averaged (TA) linear observation operator. In order to understand this undesired effect, we embed VSL's formulation into the framework of fuzzy logic (FL) theory, which thereby exposes multiple representations of the principle of limiting factors. DA experiments employing three alternative growth rate functions disclose a strong link between the lack of smoothness of the growth rate function and the loss of optimality in the estimate of the TA state. Accordingly, VSL's performance as observation operator can be enhanced by resorting to smoother FL representations of the principle of limiting factors. This finding fosters new interpretations of tree-ring-growth limitation processes.}, language = {en} } @book{SchmidtKluske1995, author = {Schmidt, Hans-J{\"u}rgen and Kluske, Sabine}, title = {Towards a no hair theorem for higher order gravit}, year = {1995}, language = {en} } @article{KluskeSchmidt1996, author = {Kluske, Sabine and Schmidt, Hans-J{\"u}rgen}, title = {Towards a cosmic no hair theorem for higher-order gravity}, year = {1996}, language = {en} } @article{Schmidt2000, author = {Schmidt, Hans-J{\"u}rgen}, title = {Topologische Aspekte in der Kosmologie}, year = {2000}, language = {de} } @article{KongDeuberKittilaeetal.2018, author = {Kong, Xiang-Zhao and Deuber, Claudia A. and Kittil{\"a}, Anniina and Somogyv{\´a}ri, M{\´a}rk and Mikutis, Gediminas and Bayer, Peter and Stark, Wendelin J. and Saar, Martin O.}, title = {Tomographic Reservoir Imaging with DNA-Labeled Silica Nanotracers: The First Field Validation}, series = {Environmental science \& technology}, volume = {52}, journal = {Environmental science \& technology}, number = {23}, publisher = {American Chemical Society}, address = {Washington}, issn = {0013-936X}, doi = {10.1021/acs.est.8b04367}, pages = {13681 -- 13689}, year = {2018}, abstract = {This study presents the first field validation of using DNA-labeled silica nanoparticles as tracers to image subsurface reservoirs by travel time based tomography. During a field campaign in Switzerland, we performed short-pulse tracer tests under a forced hydraulic head gradient to conduct a multisource-multireceiver tracer test and tomographic inversion, determining the two-dimensional hydraulic conductivity field between two vertical wells. Together with three traditional solute dye tracers, we injected spherical silica nanotracers, encoded with synthetic DNA molecules, which are protected by a silica layer against damage due to chemicals, microorganisms, and enzymes. Temporal moment analyses of the recorded tracer concentration breakthrough curves (BTCs) indicate higher mass recovery, less mean residence time, and smaller dispersion of the DNA-labeled nanotracers, compared to solute dye tracers. Importantly, travel time based tomography, using nanotracer BTCs, yields a satisfactory hydraulic conductivity tomogram, validated by the dye tracer results and previous field investigations. These advantages of DNA-labeled nanotracers, in comparison to traditional solute dye tracers, make them well-suited for tomographic reservoir characterizations in fields such as hydrogeology, petroleum engineering, and geothermal energy, particularly with respect to resolving preferential flow paths or the heterogeneity of contact surfaces or by enabling source zone characterizations of dense nonaqueous phase liquids.}, language = {en} } @book{Schulze2003, author = {Schulze, Bert-Wolfgang}, title = {Toeplitz operators, and ellipticity of boundary value problems with global projection conditions}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, publisher = {Univ.}, address = {Potsdam}, issn = {1437-739X}, pages = {66 S.}, year = {2003}, language = {en} } @unpublished{Schulze2003, author = {Schulze, Bert-Wolfgang}, title = {Toeplitz operators, and ellipticity of boundary value problems with global projection conditions}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26510}, year = {2003}, abstract = {Ellipticity of (pseudo-) differential operators A on a compact manifold X with boundary (or with edges) Y is connected with boundary (or edge) conditions of trace and potential type, formulated in terms of global projections on Y together with an additional symbolic structure. This gives rise to operator block matrices A with A in the upper left corner. We study an algebra of such operators, where ellipticity is equivalent to the Fredhom property in suitable scales of spaces: Sobolev spaces on X plus closed subspaces of Sobolev spaces on Y which are the range of corresponding pseudo-differential projections. Moreover, we express parametrices of elliptic elements within our algebra and discuss spectral boundary value problems for differential operators.}, language = {en} } @unpublished{Harutyunyan2001, author = {Harutyunyan, Anahit V.}, title = {Toeplitz operators and division theorems in anisotropic spaces of holomorphic functions in the polydisc}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26110}, year = {2001}, abstract = {This work is an introduction to anisotropic spaces, which have an ω-weight of analytic functions and are generalizations of Lipshitz classes in the polydisc. We prove that these classes form an algebra and are invariant with respect to monomial multiplication. These operators are bounded in these (Lipshitz and Djrbashian) spaces. As an application, we show a theorem about the division by good-inner functions in the mentioned classes is proved.}, language = {en} } @book{Harutjunjan2001, author = {Harutjunjan, A. V.}, title = {Toeplitz operators and division theorems in anisotropic spaces of holomorphic functions in the polydisc}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, publisher = {Univ.}, address = {Potsdam}, issn = {1437-739X}, pages = {20 S.}, year = {2001}, language = {en} } @article{GavrilovKasperMelnikovetal.1999, author = {Gavrilov, V. R. and Kasper, Uwe and Melnikov, V. N. and Rainer, Martin}, title = {Toda chains with type A(m) Lie algebra for multidimensional m-component perfect fluid cosmology}, year = {1999}, language = {en} } @article{GavrilovKasperMelnikovetal.1998, author = {Gavrilov, V. R. and Kasper, Uwe and Melnikov, V. N. and Rainer, Martin}, title = {Toda chains with type A m Lie algebra for multidimensional m-component perfect fluid cosmology}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik}, volume = {1998, 02}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik}, publisher = {Univ.}, address = {Potsdam}, pages = {12 Bl.}, year = {1998}, language = {en} } @article{PathirajaAnghileriBurlandoetal.2018, author = {Pathiraja, Sahani Darschika and Anghileri, Daniela and Burlando, Paolo and Sharma, Ashish and Marshall, Lucy and Moradkhani, Hamid}, title = {Time-varying parameter models for catchments with land use change}, series = {Hydrology and earth system sciences : HESS}, volume = {22}, journal = {Hydrology and earth system sciences : HESS}, number = {5}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1027-5606}, doi = {10.5194/hess-22-2903-2018}, pages = {2903 -- 2919}, year = {2018}, abstract = {Rapid population and economic growth in Southeast Asia has been accompanied by extensive land use change with consequent impacts on catchment hydrology. Modeling methodologies capable of handling changing land use conditions are therefore becoming ever more important and are receiving increasing attention from hydrologists. A recently developed data-assimilation-based framework that allows model parameters to vary through time in response to signals of change in observations is considered for a medium-sized catchment (2880 km(2)) in northern Vietnam experiencing substantial but gradual land cover change. We investigate the efficacy of the method as well as the importance of the chosen model structure in ensuring the success of a time-varying parameter method. The method was used with two lumped daily conceptual models (HBV and HyMOD) that gave good-quality streamflow predictions during pre-change conditions. Although both time-varying parameter models gave improved streamflow predictions under changed conditions compared to the time-invariant parameter model, persistent biases for low flows were apparent in the HyMOD case. It was found that HyMOD was not suited to representing the modified baseflow conditions, resulting in extreme and unrealistic time-varying parameter estimates. This work shows that the chosen model can be critical for ensuring the time-varying parameter framework successfully models streamflow under changing land cover conditions. It can also be used to determine whether land cover changes (and not just meteorological factors) contribute to the observed hydrologic changes in retrospective studies where the lack of a paired control catchment precludes such an assessment.}, language = {en} } @unpublished{LouisRouquier2009, author = {Louis, Pierre-Yves and Rouquier, Jean-Baptiste}, title = {Time-to-Coalescence for interacting particle systems : parallel versus sequential updating}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49454}, year = {2009}, abstract = {Studying the influence of the updating scheme for MCMC algorithm on spatially extended models is a well known problem. For discrete-time interacting particle systems we study through simulations the effectiveness of a synchronous updating scheme versus the usual sequential one. We compare the speed of convergence of the associated Markov chains from the point of view of the time-to-coalescence arising in the coupling-from-the-past algorithm. Unlike the intuition, the synchronous updating scheme is not always the best one. The distribution of the time-to-coalescence for these spatially extended models is studied too.}, language = {en} } @phdthesis{Angwenyi2019, author = {Angwenyi, David}, title = {Time-continuous state and parameter estimation with application to hyperbolic SPDEs}, doi = {10.25932/publishup-43654}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-436542}, school = {Universit{\"a}t Potsdam}, pages = {xi, 101}, year = {2019}, abstract = {Data assimilation has been an active area of research in recent years, owing to its wide utility. At the core of data assimilation are filtering, prediction, and smoothing procedures. Filtering entails incorporation of measurements' information into the model to gain more insight into a given state governed by a noisy state space model. Most natural laws are governed by time-continuous nonlinear models. For the most part, the knowledge available about a model is incomplete; and hence uncertainties are approximated by means of probabilities. Time-continuous filtering, therefore, holds promise for wider usefulness, for it offers a means of combining noisy measurements with imperfect model to provide more insight on a given state. The solution to time-continuous nonlinear Gaussian filtering problem is provided for by the Kushner-Stratonovich equation. Unfortunately, the Kushner-Stratonovich equation lacks a closed-form solution. Moreover, the numerical approximations based on Taylor expansion above third order are fraught with computational complications. For this reason, numerical methods based on Monte Carlo methods have been resorted to. Chief among these methods are sequential Monte-Carlo methods (or particle filters), for they allow for online assimilation of data. Particle filters are not without challenges: they suffer from particle degeneracy, sample impoverishment, and computational costs arising from resampling. The goal of this thesis is to:— i) Review the derivation of Kushner-Stratonovich equation from first principles and its extant numerical approximation methods, ii) Study the feedback particle filters as a way of avoiding resampling in particle filters, iii) Study joint state and parameter estimation in time-continuous settings, iv) Apply the notions studied to linear hyperbolic stochastic differential equations. The interconnection between It{\^o} integrals and stochastic partial differential equations and those of Stratonovich is introduced in anticipation of feedback particle filters. With these ideas and motivated by the variants of ensemble Kalman-Bucy filters founded on the structure of the innovation process, a feedback particle filter with randomly perturbed innovation is proposed. Moreover, feedback particle filters based on coupling of prediction and analysis measures are proposed. They register a better performance than the bootstrap particle filter at lower ensemble sizes. We study joint state and parameter estimation, both by means of extended state spaces and by use of dual filters. Feedback particle filters seem to perform well in both cases. Finally, we apply joint state and parameter estimation in the advection and wave equation, whose velocity is spatially varying. Two methods are employed: Metropolis Hastings with filter likelihood and a dual filter comprising of Kalman-Bucy filter and ensemble Kalman-Bucy filter. The former performs better than the latter.}, language = {en} } @article{KleinRama2014, author = {Klein, Markus and Rama, Juliane}, title = {Time asymptotics of e(-ith(kappa)) for analytic matrices and analytic perturbation theory}, series = {Asymptotic analysis}, volume = {89}, journal = {Asymptotic analysis}, number = {3-4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {0921-7134}, doi = {10.3233/ASY-141226}, pages = {189 -- 233}, year = {2014}, abstract = {In quantum mechanics the temporal decay of certain resonance states is associated with an effective time evolution e(-ith(kappa)), where h(.) is an analytic family of non-self-adjoint matrices. In general the corresponding resonance states do not decay exponentially in time. Using analytic perturbation theory, we derive asymptotic expansions for e(-ith(kappa)), simultaneously in the limits kappa -> 0 and t -> infinity, where the corrections with respect to pure exponential decay have uniform bounds in one complex variable kappa(2)t. In the Appendix we briefly review analytic perturbation theory, replacing the classical reference to the 1920 book of Knopp [Funktionentheorie II, Anwendungen und Weiterfuhrung der allgemeinen Theorie, Sammlung Goschen, Vereinigung wissenschaftlicher Verleger Walter de Gruyter, 1920] and its terminology by standard modern references. This might be of independent interest.}, language = {en} } @article{Rastogi2020, author = {Rastogi, Abhishake}, title = {Tikhonov regularization with oversmoothing penalty for nonlinear statistical inverse problems}, series = {Communications on Pure and Applied Analysis}, volume = {19}, journal = {Communications on Pure and Applied Analysis}, number = {8}, publisher = {American Institute of Mathematical Sciences}, address = {Springfield}, issn = {1534-0392}, doi = {10.3934/cpaa.2020183}, pages = {4111 -- 4126}, year = {2020}, abstract = {In this paper, we consider the nonlinear ill-posed inverse problem with noisy data in the statistical learning setting. The Tikhonov regularization scheme in Hilbert scales is considered to reconstruct the estimator from the random noisy data. In this statistical learning setting, we derive the rates of convergence for the regularized solution under certain assumptions on the nonlinear forward operator and the prior assumptions. We discuss estimates of the reconstruction error using the approach of reproducing kernel Hilbert spaces.}, language = {en} } @article{SaynischWagnerBaerenzungHornschildetal.2021, author = {Saynisch-Wagner, Jan and B{\"a}renzung, Julien and Hornschild, Aaron and Irrgang, Christopher and Thomas, Maik}, title = {Tide-induced magnetic signals and their errors derived from CHAMP and Swarm satellite magnetometer observations}, series = {Earth, planets and space : EPS}, volume = {73}, journal = {Earth, planets and space : EPS}, number = {1}, publisher = {Springer}, address = {Heidelberg}, issn = {1880-5981}, doi = {10.1186/s40623-021-01557-3}, pages = {11}, year = {2021}, abstract = {Satellite-measured tidal magnetic signals are of growing importance. These fields are mainly used to infer Earth's mantle conductivity, but also to derive changes in the oceanic heat content. We present a new Kalman filter-based method to derive tidal magnetic fields from satellite magnetometers: KALMAG. The method's advantage is that it allows to study a precisely estimated posterior error covariance matrix. We present the results of a simultaneous estimation of the magnetic signals of 8 major tides from 17 years of Swarm and CHAMP data. For the first time, robustly derived posterior error distributions are reported along with the reported tidal magnetic fields. The results are compared to other estimates that are either based on numerical forward models or on satellite inversions of the same data. For all comparisons, maximal differences and the corresponding globally averaged RMSE are reported. We found that the inter-product differences are comparable with the KALMAG-based errors only in a global mean sense. Here, all approaches give values of the same order, e.g., 0.09 nT-0.14 nT for M2. Locally, the KALMAG posterior errors are up to one order smaller than the inter-product differences, e.g., 0.12 nT vs. 0.96 nT for M2.}, language = {en} } @article{HammPelivanGrottetal.2020, author = {Hamm, Maximilian and Pelivan, Ivanka and Grott, Matthias and de Wiljes, Jana}, title = {Thermophysical modelling and parameter estimation of small solar system bodies via data assimilation}, series = {Monthly notices of the Royal Astronomical Society}, volume = {496}, journal = {Monthly notices of the Royal Astronomical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/staa1755}, pages = {2776 -- 2785}, year = {2020}, abstract = {Deriving thermophysical properties such as thermal inertia from thermal infrared observations provides useful insights into the structure of the surface material on planetary bodies. The estimation of these properties is usually done by fitting temperature variations calculated by thermophysical models to infrared observations. For multiple free model parameters, traditional methods such as least-squares fitting or Markov chain Monte Carlo methods become computationally too expensive. Consequently, the simultaneous estimation of several thermophysical parameters, together with their corresponding uncertainties and correlations, is often not computationally feasible and the analysis is usually reduced to fitting one or two parameters. Data assimilation (DA) methods have been shown to be robust while sufficiently accurate and computationally affordable even for a large number of parameters. This paper will introduce a standard sequential DA method, the ensemble square root filter, for thermophysical modelling of asteroid surfaces. This method is used to re-analyse infrared observations of the MARA instrument, which measured the diurnal temperature variation of a single boulder on the surface of near-Earth asteroid (162173) Ryugu. The thermal inertia is estimated to be 295 +/- 18 Jm(-2) K-1 s(-1/2), while all five free parameters of the initial analysis are varied and estimated simultaneously. Based on this thermal inertia estimate the thermal conductivity of the boulder is estimated to be between 0.07 and 0.12,Wm(-1) K-1 and the porosity to be between 0.30 and 0.52. For the first time in thermophysical parameter derivation, correlations and uncertainties of all free model parameters are incorporated in the estimation procedure that is more than 5000 times more efficient than a comparable parameter sweep.}, language = {en} } @article{CozzoniMaibaumHamm2021, author = {Cozzoni, Barbara and Maibaum, Michael and Hamm, Maximilian}, title = {Thermal analysis and constraints for the MASCOT landing site selection on the asteroid Ryugu}, series = {Planetary and space science}, volume = {205}, journal = {Planetary and space science}, publisher = {Elsevier}, address = {Oxford}, issn = {0032-0633}, doi = {10.1016/j.pss.2021.105286}, pages = {11}, year = {2021}, abstract = {In June 2018, after 4 years of cruise, the Japanese space probe Hayabusa2 [1-Watanabe S. et al.: Hayabusa2 Mission Overview. (2017)] reached the Near-Earth Asteroid (162173) Ryugu. Hayabusa2 carried a small Lander named MASCOT (Mobile Asteroid Surface Scout) [2-Ho T. M. et al.: MASCOT-The Mobile Asteroid Surface Scout onboard the Hayabusa2 mission. (2017)], jointly developed by the German Aerospace Center (DLR) and the French Space Agency (CNES), to investigate Ryugu's surface structure, composition and physical properties including its thermal behaviour and magnetization in-situ. The Microgravity User Support Centre (DLR-MUSC) in Cologne was in charge of providing all thermal conditions and constraints necessary for the selection of the final landing site and for the final operations of the Lander MASCOT on the surface of the asteroid Ryugu. This article provides a comprehensive assessment of these thermal conditions and constraints, based on predictions performed with the Thermal Mathematical Model (TMM) of MASCOT using different asteroid surface thermal models, ephemeris data for approach as well as descent and hopping trajectories, the related operation sequences and scenarios and the possible environmental conditions driven by the Hayabusa2 spacecraft. A comparison with the real telemetry data confirms the analysis and provides further information about the asteroid characteristics.}, language = {en} } @article{MuellerSchoellGroenlandScherfClaveletal.2020, author = {Mueller-Schoell, Anna and Groenland, Stefanie L. and Scherf-Clavel, Oliver and van Dyk, Madele and Huisinga, Wilhelm and Michelet, Robin and Jaehde, Ulrich and Steeghs, Neeltje and Huitema, Alwin D. R. and Kloft, Charlotte}, title = {Therapeutic drug monitoring of oral targeted antineoplastic drugs}, series = {European journal of clinical pharmacology}, volume = {77}, journal = {European journal of clinical pharmacology}, number = {4}, publisher = {Springer}, address = {Heidelberg}, issn = {0031-6970}, doi = {10.1007/s00228-020-03014-8}, pages = {441 -- 464}, year = {2020}, abstract = {Purpose This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed. Methods A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted. Results OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy. Conclusion Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.}, language = {en} } @unpublished{HarutjunjanSchulze2004, author = {Harutjunjan, Gohar and Schulze, Bert-Wolfgang}, title = {The Zaremba problem with singular interfaces as a corner boundary value problem}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26855}, year = {2004}, abstract = {We study mixed boundary value problems for an elliptic operator A on a manifold X with boundary Y , i.e., Au = f in int X, T±u = g± on int Y±, where Y is subdivided into subsets Y± with an interface Z and boundary conditions T± on Y± that are Shapiro-Lopatinskij elliptic up to Z from the respective sides. We assume that Z ⊂ Y is a manifold with conical singularity v. As an example we consider the Zaremba problem, where A is the Laplacian and T- Dirichlet, T+ Neumann conditions. The problem is treated as a corner boundary value problem near v which is the new point and the main difficulty in this paper. Outside v the problem belongs to the edge calculus as is shown in [3]. With a mixed problem we associate Fredholm operators in weighted corner Sobolev spaces with double weights, under suitable edge conditions along Z \ {v} of trace and potential type. We construct parametrices within the calculus and establish the regularity of solutions.}, language = {en} } @book{HarutjunjanSchulze2004, author = {Harutjunjan, Gohar and Schulze, Bert-Wolfgang}, title = {The zaremba problem with singular interfaces as a corner boundary value problem}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, publisher = {Univ.}, address = {Potsdam}, issn = {1437-739X}, pages = {48 S.}, year = {2004}, language = {en} } @article{HarutyunyanSchulze2006, author = {Harutyunyan, Gohar and Schulze, Bert-Wolfgang}, title = {The Zaremba problem with singular interfaces as a corner boundary value problem}, series = {Potential analysis : an international journal devoted to the interactions between potential theory, probability theory, geometry and functional analysis}, volume = {25}, journal = {Potential analysis : an international journal devoted to the interactions between potential theory, probability theory, geometry and functional analysis}, publisher = {Springer}, address = {Dordrecht}, issn = {0926-2601}, doi = {10.1007/s11118-006-9020-6}, pages = {327 -- 369}, year = {2006}, abstract = {We study mixed boundary value problems for an elliptic operator A on a manifold X with boundary Y, i.e., Au = f in int X, T (+/-) u = g(+/-) on int Y+/-, where Y is subdivided into subsets Y+/- with an interface Z and boundary conditions T+/- on Y+/- that are Shapiro-Lopatinskij elliptic up to Z from the respective sides. We assume that Z subset of Y is a manifold with conical singularity v. As an example we consider the Zaremba problem, where A is the Laplacian and T- Dirichlet, T+ Neumann conditions. The problem is treated as a corner boundary value problem near v which is the new point and the main difficulty in this paper. Outside v the problem belongs to the edge calculus as is shown in Bull. Sci. Math. ( to appear). With a mixed problem we associate Fredholm operators in weighted corner Sobolev spaces with double weights, under suitable edge conditions along Z {v} of trace and potential type. We construct parametrices within the calculus and establish the regularity of solutions.}, language = {en} } @unpublished{DinesHarutjunjanSchulze2003, author = {Dines, Nicoleta and Harutjunjan, Gohar and Schulze, Bert-Wolfgang}, title = {The Zaremba problem in edge Sobolev spaces}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-26615}, year = {2003}, abstract = {Mixed elliptic boundary value problems are characterised by conditions which have a jump along an interface of codimension 1 on the boundary. We study such problems in weighted edge Sobolev spaces and show the Fredholm property and the existence of parametrices under additional conditions of trace and potential type on the interface. Our methods from the calculus of boundary value problems on a manifold with edges will be illustrated by the Zaremba problem and other mixed problems for the Laplace operator.}, language = {en} } @book{DinesHarutjunjanSchulze2003, author = {Dines, Nicoleta and Harutjunjan, Gohar and Schulze, Bert-Wolfgang}, title = {The Zaremba problem in edge sobolev spaces}, series = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, journal = {Preprint / Universit{\"a}t Potsdam, Institut f{\"u}r Mathematik, Arbeitsgruppe Partiell}, publisher = {Univ.}, address = {Potsdam}, issn = {1437-739X}, pages = {38 S.}, year = {2003}, language = {en} } @article{DeneckeFreiberg1998, author = {Denecke, Klaus-Dieter and Freiberg, L.}, title = {The word problem for M-solid varieties of semigroups}, isbn = {981-3083-86-7}, year = {1998}, language = {en} } @article{Schulze1995, author = {Schulze, Bert-Wolfgang}, title = {The variable discrete asymptotics in pseudo-differential boundary value problems II}, year = {1995}, language = {en} } @article{Schulze1995, author = {Schulze, Bert-Wolfgang}, title = {The variable discrete asymptotics in pseudo-differential boundary value problems II}, year = {1995}, language = {en} } @article{Schulze1994, author = {Schulze, Bert-Wolfgang}, title = {The variable discrete asymptotics in pseudo-differential boundary value problems}, year = {1994}, language = {en} } @inproceedings{HaferKiy2013, author = {Hafer, J{\"o}rg and Kiy, Alexander}, title = {The university-wide introduction of an ePortfolio system as transdisciplinary task}, series = {Proceedings of the PLE Conference 2013: Learning and Diversity in the Cities of the Future}, booktitle = {Proceedings of the PLE Conference 2013: Learning and Diversity in the Cities of the Future}, editor = {Buchem, Ilona and Graham, Attwell and Tur, Gemma}, publisher = {Logos}, address = {Berlin}, pages = {363 -- 373}, year = {2013}, language = {en} } @article{KleinRosenberger2021, author = {Klein, Markus and Rosenberger, Elke}, title = {The tunneling effect for Schr{\"o}dinger operators on a vector bundle}, series = {Analysis and mathematical physics}, volume = {11}, journal = {Analysis and mathematical physics}, number = {2}, publisher = {Springer International Publishing AG}, address = {Cham (ZG)}, issn = {1664-2368}, doi = {10.1007/s13324-021-00485-5}, pages = {35}, year = {2021}, abstract = {In the semiclassical limit (h) over bar -> 0, we analyze a class of self-adjoint Schrodinger operators H-(h) over bar = (h) over bar L-2 + (h) over barW + V center dot id(E) acting on sections of a vector bundle E over an oriented Riemannian manifold M where L is a Laplace type operator, W is an endomorphism field and the potential energy V has non-degenerate minima at a finite number of points m(1),... m(r) is an element of M, called potential wells. Using quasimodes of WKB-type near m(j) for eigenfunctions associated with the low lying eigenvalues of H-(h) over bar, we analyze the tunneling effect, i.e. the splitting between low lying eigenvalues, which e.g. arises in certain symmetric configurations. Technically, we treat the coupling between different potential wells by an interaction matrix and we consider the case of a single minimal geodesic (with respect to the associated Agmon metric) connecting two potential wells and the case of a submanifold of minimal geodesics of dimension l + 1. This dimension l determines the polynomial prefactor for exponentially small eigenvalue splitting.}, language = {en} } @misc{KleinRosenberger2018, author = {Klein, Markus and Rosenberger, Elke}, title = {The tunneling effect for a class of difference operators}, series = {Reviews in Mathematical Physics}, volume = {30}, journal = {Reviews in Mathematical Physics}, number = {4}, publisher = {World Scientific}, address = {Singapore}, issn = {0129-055X}, doi = {10.1142/S0129055X18300029}, pages = {42}, year = {2018}, abstract = {We analyze a general class of self-adjoint difference operators H-epsilon = T-epsilon + V-epsilon on l(2)((epsilon Z)(d)), where V-epsilon is a multi-well potential and v(epsilon) is a small parameter. We give a coherent review of our results on tunneling up to new sharp results on the level of complete asymptotic expansions (see [30-35]). Our emphasis is on general ideas and strategy, possibly of interest for a broader range of readers, and less on detailed mathematical proofs. The wells are decoupled by introducing certain Dirichlet operators on regions containing only one potential well. Then the eigenvalue problem for the Hamiltonian H-epsilon is treated as a small perturbation of these comparison problems. After constructing a Finslerian distance d induced by H-epsilon, we show that Dirichlet eigenfunctions decay exponentially with a rate controlled by this distance to the well. It follows with microlocal techniques that the first n eigenvalues of H-epsilon converge to the first n eigenvalues of the direct sum of harmonic oscillators on R-d located at several wells. In a neighborhood of one well, we construct formal asymptotic expansions of WKB-type for eigenfunctions associated with the low-lying eigenvalues of H-epsilon. These are obtained from eigenfunctions or quasimodes for the operator H-epsilon acting on L-2(R-d), via restriction to the lattice (epsilon Z)(d). Tunneling is then described by a certain interaction matrix, similar to the analysis for the Schrodinger operator (see [22]), the remainder is exponentially small and roughly quadratic compared with the interaction matrix. We give weighted l(2)-estimates for the difference of eigenfunctions of Dirichlet-operators in neighborhoods of the different wells and the associated WKB-expansions at the wells. In the last step, we derive full asymptotic expansions for interactions between two "wells" (minima) of the potential energy, in particular for the discrete tunneling effect. Here we essentially use analysis on phase space, complexified in the momentum variable. These results are as sharp as the classical results for the Schrodinger operator in [22].}, language = {en} }