484 research outputs found
Dagvlinders van Europa
No full textDagvlinders is gebaseerd op de ETI CD-ROM Dagvlinders van Europa (Van Halder, Wynhoff en Van Swaay, 2000). Dit programma toont informatie over meer dan 400 Europese dagvlinders. Elke soort is geïllustreerd met gedetailleerde tekeningen en foto's. De tekst behandelt ecologie, verspreiding, habitat en vluchtperiode. Het programma bevat verder een kennistest en interactieve verspreidingkaarten
Dagvlinders van Europa
No full textDagvlinders is gebaseerd op de ETI CD-ROM Dagvlinders van Europa (Van Halder, Wynhoff en Van Swaay, 2000). Dit programma toont informatie over meer dan 400 Europese dagvlinders. Elke soort is geïllustreerd met gedetailleerde tekeningen en foto's. De tekst behandelt ecologie, verspreiding, habitat en vluchtperiode. Het programma bevat verder een kennistest en interactieve verspreidingkaarten
Replication Data for: Transect-rapport 3733: Een Archeologisch Bureauonderzoek en inventariserend veldonderzoek, verkennende en karterende fase. Halder, Halder 1A. Gemeente Sint-Michielsgestel.
No full textUit het veldonderzoek is gebleken dat de ondergrond in het plangebied bestaat uit dekzand. De top
van het dekzand bevindt zich op een diepte tussen 120 en 190 cm -Mv (tussen 4,1 en 4,4 m +NAP).
Boven het dekzand is een humeus dek aanwezig met een dikte tussen 85 en 130 cm, die grotendeels
te interpreteren is als esdek. De onderzijde van dit dek is iets afwijkend qua kleur. Vermoedelijk is aan
de onderzijde nog een akker- of cultuurlaag aanwezig. Dit zou ook de relatief grote dikte van het
humeuze dek kunnen verklaren. Bij het doorzoeken van de opgeboorde grondmonsters zijn
fragmenten aardewerk uit de Late IJzertijd-Romeinse Tijd en Middeleeuwen-Nieuwe Tijd aangetroffen.
Deze zijn afkomstig uit het esdek en de akker/cultuurlaag, met uitzondering van een fragment
handgevormd aardewerk uit de Late IJzertijd-Romeinse Tijd die in de top van de C-horizont is
aangetroffen. Gezien de resultaten van het veldonderzoek is de kans zeer hoog dat er in het
plangebied archeologische resten aanwezig zijn. Vermoedelijk ligt de nadruk op de Romeinse Tijd,
gezien de ligging in een vicus en het aantreffen van aardewerk uit deze periode in de boringen. De
verwachting voor resten uit de periode Laat-Paleolithicum – Mesolithicum kan naar beneden worden
bijgesteld aangezien de top van het dekzand dermate is afgetopt dat vindplaatsen die zich kenmerken
door een vondststrooiing niet meer intact zullen zijn
Fractional dynamical model for the generation of ECG like signals from filtered coupled Van-der Pol oscillators
No full textIn this paper, an incommensurate fractional order (FO) model has been proposed to generate ECG like waveforms. Earlier investigation of ECG like waveform generation is based on two identical Van-der Pol (VdP) family of oscillators, which are coupled by time delays and gains. In this paper, we suitably modify the three state equations corresponding to the nonlinear cross-product of states, time delay coupling of the two oscillators and low-pass filtering, using the concept of fractional derivatives. Our results show that a wide variety of ECG like waveforms can be simulated from the proposed generalized models, characterizing heart conditions under different physiological conditions. Such generalization of the modelling of ECG waveforms may be useful to understand the physiological process behind ECG signal generation in normal and abnormal heart conditions. Along with the proposed FO models, an optimization based approach is also presented to estimate the VdP oscillator parameters for representing a realistic ECG like signal
MD Simulations and FRET Reveal an Environment-Sensitive Conformational Plasticity of Importin-β
No full textAbstractThe nuclear pore complex mediates nucleocytoplasmic transport of macromolecules in eukaryotic cells. Transport through the pore is restricted by a hydrophobic selectivity filter comprising disordered phenylalanine-glycine-rich repeats of nuclear pore proteins. Exchange through the pore requires specialized transport receptors, called exportins and importins, that interact with cargo proteins in a RanGTP-dependent manner. These receptors are highly flexible superhelical structures composed of HEAT-repeat motifs that adopt various degrees of extension in crystal structures. Here, we performed molecular-dynamics simulations using crystal structures of Importin-β in its free form or in complex with nuclear localization signal peptides as the starting conformation. Our simulations predicted that initially compact structures would adopt extended conformations in hydrophilic buffers, while contracted conformations would dominate in more hydrophobic solutions, mimicking the environment of the nuclear pore. We confirmed this experimentally by Förster resonance energy transfer experiments using dual-fluorophore-labeled Importin-β. These observations explain seemingly contradictory crystal structures and suggest a possible mechanism for cargo protection during passage of the nuclear pore. Such hydrophobic switching may be a general principle for environmental control of protein function
Efficient sampling and solver enhancement for uncertainty quantification
No full textThe focus of this thesis is on the development of efficient and robust uncertainty quantiÞcation algorithms that can be used for a wide range of applications. The goal is to determine how likely certain outcomes are if some aspects of the application are not known exactly, i.e., in case of limited prior knowledge or uncertainties in the parameter values. We focus in particular on quantifying uncertainties in the output of a mathematical model induced by uncertainties in the
input parameters, often referred to as forward propagation of parametric uncertainties. The first part of this thesis discusses how to signiÞcantly reduce the required number of samples needed in the forward propagation of uncertainties. In particular, if the quantity of interest is highly non-linear or discontinuous depending on the input parameters, Gibbs phenomena may occur, which deteriorate the accuracy globally. As we often do not know beforehand if a quantity of
interest is smooth or discontinuous, we propose a new algorithm that works in both cases. In the second part of this thesis, instead of placing samples optimally in order to reduce the overall computational cost of forward propagation, we opt to increase the accuracy of the quantity of interest that is outputted by the solver. To clarify, when using numerical discretisation to compute outcomes of the mathematical model, the resolution of the computational grid determines the accuracy of the quantity of interest, but it also determines the computational time it takes to compute this quantity of interest. In general, a quantity of interest that is computed using a coarse computational grid is fast to compute but also inaccurate. As a remedy, we opt to use machine learning to increase the accuracy of a quantity of interest that is computed on a coarse grid, as it is able to deal with highly non-linear behaviour and high-dimensional input/ output relations. The main topics of this thesis are uncertainty quantiÞcation and machine learning. We assume that the reader possesses basic prior knowledge on these two subjects. Furthermore, the test cases discussed in both Part I and II of this thesis assume prior knowledge on basic numerical discretisation techniques, in particular Þnite volume methods
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