Multiscale reconstruction of time series

A new method is proposed which allows a reconstruction of time series based on higher order multiscale statistics given by a hierarchical process. This method is able to model the time series not only on a specific scale but for a range of scales. It is possible to generate complete new time series, or to model the next steps for a given sequence of data. The method itself is based on the joint probability density which can be extracted directly from given data, thus no estimation of parameters is necessary. The results of this approach are shown for a real world dataset, namely for turbulence. The unconditional and conditional probability densities of the original and reconstructed time series are compared and the ability to reproduce both is demonstrated. Therefore in the case of Markov properties the method proposed here is able to generate artificial time series with correct n-point statistics.Comment: 4 pages, 3 figure

Stochastic analysis of different rough surfaces

This paper shows in detail the application of a new stochastic approach for the characterization of surface height profiles, which is based on the theory of Markov processes. With this analysis we achieve a characterization of the scale dependent complexity of surface roughness by means of a Fokker-Planck or Langevin equation, providing the complete stochastic information of multiscale joint probabilities. The method is applied to several surfaces with different properties, for the purpose of showing the utility of this method in more details. In particular we show the evidence of Markov properties, and we estimate the parameters of the Fokker-Planck equation by pure, parameter-free data analysis. The resulting Fokker-Planck equations are verified by numerical reconstruction of conditional probability density functions. The results are compared with those from the analysis of multi-affine and extended multi-affine scaling properties which is often used for surface topographies. The different surface structures analysed here show in details advantages and disadvantages of these methods.Comment: Minor text changes to be identical with the published versio

Ocorrencia e abundância de espécies de plantas ameaçadas de extinção no entorno do reservatório da UHE Barra Grande.

Modelos de ocorrência e abundância de espécies são ferramentas atuais que devem ser incorporadas na conservação da biodiversidade no entorno de reservatórios de usinas hidroelétricas, prevendo ou planejando ações necessárias para mitigar os impactos ambientais destes empreendimentos. Neste estudo, nossos objetivos foram: modelar a ocorrência e abundância de espécies de plantas ameaçadas de extinção, verificar a relação entre a ocorrência prevista e a abundância observada e avaliar se os modelos baseados em abundância são mais eficientes em predizer a ocorrência do que aqueles baseados em dados de ocorrência (0/1). Representantes individuais de nove espécies (Araucaria angustifolia (Bertol.) Kuntze (Araucariaceae), Butia eriospatha (Mart. ex Drude) Becc. (Arecaceae), Clethra scabra Pers. (Clethraceae), Dicksonia sellowiana (Presl.) Hook. (Dicksoniaceae), Erythrina falcata Benth. (Fabaceae), Maytenus ilicifolia (Schrad.) Planch. (Celastraceae), Myrocarpus frondosus Allemão (Fabaceae), Podocarpus lambertii Klotzsch ex Endl. (Podocarpaceae) e Trithrinax brasiliensis Mart (Arecaceae)) foram contados em 388 parcelas (10x50m) aleatoriamente alocadas e georreferenciadas no entorno do reservatório da UHE Barra Grande (SC/RS). Modelamos sua relação com 15 variáveis ambientais utilizando dados de ocorrência (GLM) e abundância (Modelos Hurdle e Zero-inflado). Em geral, os modelos de ocorrência foram mais precisos do que os modelos de abundância. Para todas as espécies, a abundância observada foi correlacionada com a probabilidade de ocorrência, sugerindo que estudos futuros poderiam utilizar esta informação, em vez da abundância. Reconstruir padrões de abundância e de ocorrência é uma importante ferramenta para o planejamento de ações de conservação e manejo de espécies ameaçadas, permitindo que sejam indicadas as melhores áreas para a coleta e reintrodução de germoplasma vegetal ou mesmo a escolha de áreas de conservação com maior probabilidade de manter populações viáveis

Towards improving the accuracy of aortic transvalvular pressure gradients: rethinking Bernoulli

The transvalvular pressure gradient (TPG) is commonly estimated using the Bernoulli equation. However, the method is known to be inaccurate. Therefore, an adjusted Bernoulli model for accurate TPG assessment was developed and evaluated. Numerical simulations were used to calculate TPGCFD in patient-specific geometries of aortic stenosis as ground truth. Geometries, aortic valve areas (AVA), and flow rates were derived from computed tomography scans. Simulations were divided in a training data set (135 cases) and a test data set (36 cases). The training data was used to fit an adjusted Bernoulli model as a function of AVA and flow rate. The model-predicted TPGModel was evaluated using the test data set and also compared against the common Bernoulli equation (TPGB). TPGB and TPGModel both correlated well with TPGCFD (r > 0.94), but significantly overestimated it. The average difference between TPGModel and TPGCFD was much lower: 3.3 mmHg vs. 17.3 mmHg between TPGB and TPGCFD. Also, the standard error of estimate was lower for the adjusted model: SEEModel = 5.3 mmHg vs. SEEB = 22.3 mmHg. The adjusted model's performance was more accurate than that of the conventional Bernoulli equation. The model might help to improve non-invasive assessment of TPG. Graphical abstract Processing pipeline for the definition of an adjusted Bernoulli model for the assessment of transvalvular pressure gradient. Using CT image data, the patient specific geometry of the stenosed AVs were reconstructed. Using this segmentation, the AVA as well as the volume flow rate was calculated and used for model definition. This novel model was compared against classical approaches on a test data set, which was not used for the model definition

Stochastic analysis of surface roughness

For the characterization of surface height profiles we present a new stochastic approach which is based on the theory of Markov processes. With this analysis we achieve a characterization of the complexity of the surface roughness by means of a Fokker-Planck or Langevin equation, providing the complete stochastic information of multiscale joint probabilities. The method was applied to different road surface profiles which were measured with high resolution. Evidence of Markov properties is shown. Estimations for the parameters of the Fokker-Planck equation are based on pure, parameter free data analysis

youth Digital Skills Indicator:German questionnaire

The youth Digital Skills Indicator was developed as part of the ‘Youth Skills (ySKILLS)’ project and added to the ‘From Digital Skills to Tangible Outcomes’ digital skills measurement toolkit.Please read the accompanying document on the underlying rationale for these scales and on how to create and use composite scales in the following document: Helsper, E.J., Schneider, L., van Deursen, A.J.A.M., van Laar, E. (2021). The youth Digital Skills Indicator: Report on the conceptualisation and development of the ySKILLS digital skills measure. KU Leuven, Leuven: ySKILLS. Available at: https://yskills.eu

Molecular characterization of the viaB locus encoding the biosynthetic machinery for Vi capsule formation in Salmonella Typhi

The Vi capsular polysaccharide (CPS) of Salmonella enterica serovar Typhi, the cause of human typhoid, is important for infectivity and virulence. The Vi biosynthetic machinery is encoded within the viaB locus composed of 10 genes involved in regulation of expression (tviA), polymer synthesis (tviB-tviE), and cell surface localization of the CPS (vexA-vexE). We cloned the viaB locus from S. Typhi and transposon insertion mutants of individual viaB genes were characterized in Escherichia coli DH5α. Phenotype analysis of viaB mutants revealed that tviB, tviC, tviD and tviE are involved in Vi polymer synthesis. Furthermore, expression of tviB-tviE in E. coli DH5α directed the synthesis of cytoplasmic Vi antigen. Mutants of the ABC transporter genes vexBC and the polysaccharide copolymerase gene vexD accumulated the Vi polymer within the cytoplasm and productivity in these mutants was greatly reduced. In contrast, de novo synthesis of Vi polymer in the export deficient vexA mutant was comparable to wild-type cells, with drastic effects on cell stability. VexE mutant cells exported the Vi, but the CPS was not retained at the cell surface. The secreted polymer of a vexE mutant had different physical characteristics compared to the wild-type Vi

Ultrastructural changes in chemically induced preneoplastic focal lesions in the rat liver: a stereological study

Ultrastructural changes were investigated and quantified, using a stereological approach, in early gamma-glutamyl transpeptidase (GGT)-positive focal lesions, induced in the rat liver by treatment with a single initiating dose of diethylnitrosamine (DENA) followed by promotion with phenobarbitone (PB) for 30 weeks. Within the extra-hepato cyte environment of focal tissue, the mean volume occupied by Ito cells was markedly decreased, whilst that occupied by endothelial and Kupffer cells was increased, when compared to uninvolved tissue from the same rat livers. The bile canalicull were dilated, but nosignificant differences in the mean volume occupkd by the sinusoidal and Disse spaces were noted. In focal hepatocytes there was a striking overproduction of lipid droplets and proliferation of smooth endoplasmic reticulum (sER). Whorls of concentrically arranged, parallel ER membranes were found only in the hepatocytes of preneoplastic foci, in association with the proliferated sER, and never in the surrounding, uninvolved tissue. The Increase In mean volume of the sER, lipid droplet and cytoplasmic matrix compartments, together with the appearance of whorls, were the major contributing factors to the marked hypertrophy seen in focal hepatocytes. The mean volume of the rough endoplasmic reticulum, mitochondrial, lysosomal, peroxisomal and nuclear compartments per hepatocyte also Increased, but contributed to a lesser extent to the cellular hypertrophy. It is speculated that whorls may be structural adaptations, resulting from a possible alteration in the normalfeedback control of cholesterol synthesis, for the production of sterols and the biogenesis of sER in eosinophilic-type focal cells. The significance of changes observed in focal tissue, and the high biological variation noted between foci, is discussed in relation to the hepatocarcinogenic proces