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Search Results: 1 - 10 of 963 matches for " Tanja Thorskov Bladt "
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Anticancer and Antifungal Compounds from Aspergillus, Penicillium and Other Filamentous Fungi
Tanja Thorskov Bladt,Jens Christian Frisvad,Peter Boldsen Knudsen,Thomas Ostenfeld Larsen
Molecules , 2013, DOI: 10.3390/molecules180911338
Abstract: This review covers important anticancer and antifungal compounds reported from filamentous fungi and in particular from Aspergillus, Penicillium and Talaromyces. The taxonomy of these fungi is not trivial, so a focus of this review has been to report the correct identity of the producing organisms based on substantial previous in-house chemotaxonomic studies.
Bio-Activity and Dereplication-Based Discovery of Ophiobolins and Other Fungal Secondary Metabolites Targeting Leukemia Cells
Tanja Thorskov Bladt,Claudia Dürr,Peter Boldsen Knudsen,Sara Kildgaard,Jens Christian Frisvad,Charlotte Held Gotfredsen,Martina Seiffert,Thomas Ostenfeld Larsen
Molecules , 2013, DOI: 10.3390/molecules181214629
Abstract: The purpose of this study was to identify and characterize fungal natural products (NPs) with in vitro bioactivity towards leukemia cells. We based our screening on a combined analytical and bio-guided approach of LC-DAD-HRMS dereplication, explorative solid-phase extraction (E-SPE), and a co-culture platform of CLL and stromal cells. A total of 289 fungal extracts were screened and we tracked the activity to single compounds in seven of the most active extracts. The novel ophiobolin U was isolated together with the known ophiobolins C, H, K as well as 6-epiophiobolins G, K and N from three fungal strains in the Aspergillus section Usti. Ophiobolins A, B, C and K displayed bioactivity towards leukemia cells with induction of apoptosis at nanomolar concentrations. The remaining ophiobolins were mainly inactive or only slightly active at micromolar concentrations. Dereplication of those ophiobolin derivatives possessing different activity in combination with structural analysis allowed a correlation of the chemical structure and conformation with the extent of bioactivity, identifying the hydroxy group at C3 and an aldehyde at C21, as well as the A/B- cis ring structure, as indispensible for the strong activity of the ophiobolins. The known compounds penicillic acid, viridicatumtoxin, calbistrin A, brefeldin A, emestrin A, and neosolaniol monoacetate were identified from the extracts and also found generally cytotoxic.
Pricing American Options Using Transition Probabilities: A Dynamical Systems Approach  [PDF]
Rocio Elizondo, Pablo Padilla, Mogens Bladt
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.56056
Abstract:

We give a new way to price American options by using Samuelson’s formula. We first obtain the option price corresponding to a European option at time t, weighing it by the probability that the underlying asset takes the value S at time t. We then use Samuelson’s formula with this factor which is given by the solution of the Fokker-Planck (Kolmogorov) equation for the transition probability density. The main advantage of this approach is that we can systematically introduce the effect of macroeconomic factors. If a macroeconomic framework is given by a dynamical system in the form of a set of ordinary differential equations we only have to solve a partial differential equation for the transition probability density. In this context, we verify, for the sake of consistency, that this formula coincides with the Black-Scholes model and compare several numerical implementations.

Simple simulation of diffusion bridges with application to likelihood inference for diffusions
Mogens Bladt,Michael S?rensen
Statistics , 2014, DOI: 10.3150/12-BEJ501
Abstract: With a view to statistical inference for discretely observed diffusion models, we propose simple methods of simulating diffusion bridges, approximately and exactly. Diffusion bridge simulation plays a fundamental role in likelihood and Bayesian inference for diffusion processes. First a simple method of simulating approximate diffusion bridges is proposed and studied. Then these approximate bridges are used as proposal for an easily implemented Metropolis-Hastings algorithm that produces exact diffusion bridges. The new method utilizes time-reversibility properties of one-dimensional diffusions and is applicable to all one-dimensional diffusion processes with finite speed-measure. One advantage of the new approach is that simple simulation methods like the Milstein scheme can be applied to bridge simulation. Another advantage over previous bridge simulation methods is that the proposed method works well for diffusion bridges in long intervals because the computational complexity of the method is linear in the length of the interval. For $\rho$-mixing diffusions the approximate method is shown to be particularly accurate for long time intervals. In a simulation study, we investigate the accuracy and efficiency of the approximate method and compare it to exact simulation methods. In the study, our method provides a very good approximation to the distribution of a diffusion bridge for bridges that are likely to occur in applications to statistical inference. To illustrate the usefulness of the new method, we present an EM-algorithm for a discretely observed diffusion process.
Simulation of multivariate diffusion bridge
Mogens Bladt,Samuel Finch,Michael S?rensen
Statistics , 2014,
Abstract: We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously proposed simulation method for one-dimensional bridges to the multi-variate setting. First a method of simulating approximate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges. The new method is much more generally applicable than previous methods. Another advantage is that the new method works well for diffusion bridges in long intervals because the computational complexity of the method is linear in the length of the interval. In a simulation study the new method performs well, and its usefulness is illustrated by an application to Bayesian estimation for the multivariate hyperbolic diffusion model.
Teaching PCA through Letter Recognition  [PDF]
Tanja Van Hecke
Creative Education (CE) , 2011, DOI: 10.4236/ce.2011.23040
Abstract: This article presents the use of a real life problem to reach a deeper understanding among students of the benefits of principal components analysis. Pattern recognition applied on the 26 letters of the alphabet is a recognizable topic for the students. Moreover it is still verifiable with computer algebra software. By means of well defined exercises the student can be guided in an active way through the learning process.
Influence of Random Pinning on the Crystallization Process in Suspensions of Hard Spheres  [PDF]
Sven Dorosz, Tanja Schilling
Journal of Crystallization Process and Technology (JCPT) , 2014, DOI: 10.4236/jcpt.2014.42012
Abstract: We discuss crystal formation in supersaturated suspensions of monodisperse hard spheres with a concentration of hard spheres randomly pinned in space and time. The pinning procedure introduces an external length scale and an external time scale that restrict the accessible number of configureurations and ultimately the number of pathways leading to crystallization. We observe a significant drop in the nucleation rate density at a characteristic pinning concentration that can be directly related to the structure of the critical nucleus and the dynamics of its formation in the unpinned system.
Appendix 3: Summary of the Evaluation of the Seminar The Effective Library”
Tanja Notten
Liber Quarterly : The Journal of European Research Libraries , 2002,
Abstract:
Steuergruppen von Schulnetzwerken: Gestaltungsm glichkeiten durch Distinktionen in Erweiterungsprozessen Steering Committee Members in School Networks: Distinctions in Admission Processes Miembros del Comité Directivo en las redes escolares: Distinciones en los procesos de admisión
Tanja Sturm
Forum : Qualitative Social Research , 2010,
Abstract: Netzwerke, in denen Personen kooperieren, um im Schulsystem nachhaltige Schul- und Professionalit tsentwicklung zu initiieren und zu etablieren, werden seit Ende der 1990er Jahre zunehmend aufgebaut. Netzwerke sind meist interessiert, sich auszuweiten, um m glichst viele Lehrende in Innovationen einzubeziehen. Steuergruppen stellen das operative Zentrum von Netzwerken dar. Sie übernehmen die Koordination und Organisation der Schulentwicklungsinitiativen eines Netzwerks und dienen als solche u.a. als Schnittstelle zwischen den bereits kooperierenden und potenziell neuen Mitgliedern. Bislang gibt es jedoch kaum Erkenntnisse darüber, wie die Steuergruppenmitglieder diesen Vermittlungsprozess gestalten und woran sie sich dabei orientieren. In diesem Beitrag soll an diesem Forschungsdesiderat angesetzt werden, indem die von Steuergruppenmitgliedern formulierten Zugangsm glichkeiten zum Netzwerk untersucht werden, die im Rahmen einer qualitativ angelegten Studie mithilfe problemzentrierter Interviews erhoben wurden. Die Befragungen wurden im Winter 2007/8 im Rahmen der sterreichischen Regionalen Netzwerke, einer von vier Ma nahmen eines landesweiten Projekts zur St rkung des mathematisch-naturwissenschaftlichen Unterrichts, durchgeführt. Drei unterschiedlich ausgestaltete Vermittlungsprozesse, die sich im Spannungsfeld von Sach- und Schulstrukturorientierung einerseits und den Vorstellungen zu inhaltlichen Gemeinsamkeiten und Unterschieden innerhalb des Netzwerks andererseits bewegen, konnten aus den Interviews generiert werden. Die drei rekonstruierten Typen von Zugangsm glichkeiten – sachlich-homogen, sachlich-heterogen und bürokratisch-homogen – die durch sogenannte Distinktionen, d.h. habituell vorgenommene Bewertungsformen, realisiert werden, werden anhand von Fallbeispielen illustriert und miteinander kontrastiert. Auf der Grundlage der Ergebnisse werden (Forschungs-) Perspektiven für den Einsatz des Entwicklungsansatzes der Schulnetzwerke formuliert. URN: urn:nbn:de:0114-fqs1003234 School networks—defined as people cooperating in order to initiate and emphasize school and professional development—have been established in German speaking areas since the beginning of the 1990s. One of their common goals is to raise the number of their active members. This purpose is connected to the idea of incorporating as many teachers as possible into possible innovations of the network. Steering committees are the operation centers of these kinds of school networks. They coordinate and organize the school and professional development initiatives of a network. Therefo
Music libraries and collections in Slovenia and abroad: characteristics and development trends
Tanja Curhalek
Knji?nica : Revija za Podro?je Bibliotekarstva in Informacijske Znanosti , 2003,
Abstract: Music libraries and collections with their materials, equipment and activities differ from general libraries, which mostly contain book materials. Library users are searching daily for more non-book music materials, specific for music libraries and collections, therefore detailed research on the situation and organization of such libraries and collections should be made. A detailed research was carried out on comprehensive Slovenian music libraries and collections. Consequently, a view was obtained of the situation of music librarianship in Slovenia, using a questionnaire and by communicating with librarians of the Music Collection of the National and University Library in Ljubljana, the Library of Department of Musicology at the Faculty of Arts in Ljubljana and the Library of the Academy of Music in Ljubljana, during the years 2000 and 2002. The research showed that music librarianship is not developed enough and that the Slovene public knows little about it, while in foreign countries libraries are contemporarily developed, well organized and extended, forming professional associations.
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