316 research outputs found
Predicting spatio-temporal time series using dimension reduced local states
No full textWe present a method for both cross-estimation and iterated time series prediction of spatio-temporal dynamics based on local modelling and dimension reduction techniques. Assuming homogeneity of the underlying dynamics, we construct delay coordinates of local states and then further reduce their dimensionality through Principle Component Analysis. The prediction uses nearest neighbour methods in the space of dimension reduced states to either cross-estimate or iteratively predict the future of a given frame. The effectiveness of this approach is shown for (noisy) data from a (cubic) Barkley model, the Bueno-Orovio-Cherry-Fenton model, and the Kuramoto-Sivashinsky model
Multiscale modeling of dendritic growth kinetics with liquid convection
No full textLa solidificación dendrítica es un problema multiescala en el que la interacción entre mecanismos físicos a diferentes escalas de longitud determina la cinética de crecimiento y, por tanto, las propiedades termofísicas del material solidificado. El modelo de Dendritic Needle Network (DNN) para aleaciones binarias se desarrolló para salvar la brecha entre los métodos de modelado bien establecidos, como el método de phase-field (PF), que opera en la escala del radio de la punta dendrítica, y los métodos de mayor escala, como los métodos de cellular automaton (CA) que operan en una escala de varios órdenes de magnitud mayor. En el modelo DNN, las finas ramas dendríticas en forma de aguja que crecen en una red jerárquica se representan como paraboloides, de manera que la dinámica de crecimiento de dicha red se describe por completo mediante los radios y las velocidades de las puntas de sus agujas. Las implementaciones anteriores del modelo DNN se han verificado en numerosos estudios y se ha demostrado que predicen con éxito escalas de longitud importantes, como el espaciado del brazo dendrítico primario.
Las corrientes advectivas inducidas por la flotabilidad en la masa fundida líquida, inevitables en las condiciones experimentales terrestres, alteran sustancialmente la dinámica de crecimiento dendrítico y son a menudo responsables de la formación de defectos. En esta tesis se amplía el modelo DNN para incorporar el flujo de fluidos mediante la implementación de un solver Navier- Stokes (NS) para dos casos importantes: (i) crecimiento dendrítico tridimensional en condiciones isotérmicas y (ii) crecimiento dendrítico bidimensional en un gradiente de temperatura, es decir, solidificación direccional. La nueva implementación tridimensional de NS se verifica mediante la comparación con varios puntos de referencia de la mecánica de fluidos. Todas las versiones actuales del modeloDNNestán implementadas en el lenguaje de programación CUDApara su paralelización en las unidades de procesamiento gráfico (GPU) de Nvidia.
Presentamos varias aplicaciones, cada una de las cuales proporciona más información sobre diferentes aspectos de la solidificación dendrítica. Una comparación entre las morfologías 2D y 3D y la dinámica de crecimiento de los granos equiaxados bajo un flujo de entrada forzado muestra que las simulaciones 3D son indispensables para la comparación cuantitativa con los datos experimentales, especialmente cuando hay flujo de fluido involucrado. Se estudia la selección del espaciado en varias aleaciones binarias en 2D y 3D, con y sin flujo de fluido, comparando con resultados de PF y experimentales. Se investiga el crecimiento oscilante observado experimentalmente en superaleaciones base níquel mediante el modelo DNN 2D para la solidificación direccional. Por último, se presentan los resultados preliminares de una comparación cuantitativa entre PF, DNN y el Grain Envelope Model (GEM) basada en dos casos de referencia.
Los principales resultados de la sección 6.1 de esta tesis se han publicado en
T. Isensee, D. Tourret,
Three-dimensional needle network model for dendritic growth with fluid flow,
IOP Conference Series: Materials Science and Engineering 861, 012049 (2020), arXiv:2003.05248 [physics.comp-ph]
La sección 6.3.1 de esta tesis ha sido publicada en
B. Bellon, A. K. Boukellal, T. Isensee, O. M. Wellborn, K. P. Trumble,
M. J. M. Krane, M. S. Titus, D. Tourret, J. LLorca,
Multiscale prediction of microstructure length scales in metallic alloy casting,
Acta Materialia 207, 116686 (2021),
arXiv:2101.07780 [cond-mat.mtrl-sci]
Las secciones 6.3.2 - 6.4 de esta tesis se han publicado en
T. Isensee, D. Tourret,
Convective effects on columnar dendritic solidification – A multiscale dendritic needle network study,
Acta Materialia 234, 118035 (2022),
arXiv:2205.07952 [cond-mat.mtrl-sci]
ABSTRACT
Dendritic solidification is a multiscale problem in which the interplay between physical mechanisms on different length scales determines the growth kinetics and, thus, the solidified material’s thermophysical properties. The Dendritic Needle Network (DNN) model for binary alloys was developed to bridge the gap between well-established modeling methods, such as the phase-field (PF) method, operating on the scale of the dendritic tip radius, and larger scale methods, such as cellular automaton (CA) methods which operate on a scale several orders of magnitude larger. Within the DNN model, dendritic needle-like thin branches growing in a hierarchical network are represented as paraboloids, such that the growth dynamics of such a network are entirely described by the tip radii and tip velocities of its needles. Earlier implementations of the DNN model have been verified in numerous studies and were shown to successfully predict important length scales, such as the primary dendritic arm spacing.
Buoyancy-induced advective currents in the liquid melt, unavoidable under Earth-based experimental conditions, alter the dendritic growth dynamics substantially and are often responsible for defect formation. Within this thesis, the DNN model is extended to incorporate fluid flow via the implementation of a Navier-Stokes (NS) solver for two important cases: (i) three-dimensional dendritic growth under isothermal conditions and (ii) two-dimensional dendritic growth in a temperature gradient, i.e., directional solidification. The new three-dimensional NS implementation is verified by comparison to several fluid mechanics benchmarks. All current versions of the DNN model are implemented in the CUDA programming language for parallelization on Nvidia graphics processing units (GPUs).
We present several applications, each giving more insight into different aspects of dendritic solidification. A comparison between 2D and 3D morphologies and growth dynamics of equiaxed grains under a forced inflow confirms that 3D simulations are indispensable for quantitative comparison to experimental data, especially when fluid flow is involved. Spacing selection in several binary alloys is studied in 2D and 3D, with and without fluid flow, comparing to PF and experimental results. Experimentally observed oscillatory growth in nickel-based superalloys is investigated via the 2D DNN model for directional solidification. Finally, preliminary results of a quantitative comparison between PF, DNN, and the grain envelope model (GEM) based on two benchmark cases are presented.
The main results of Sec. 6.1 of this thesis have been published in
T. Isensee, D. Tourret,
Three-dimensional needle network model for dendritic growth with fluid flow,
IOP Conference Series: Materials Science and Engineering 861, 012049 (2020),
arXiv:2003.05248 [physics.comp-ph]
Results from Sec. 6.3.1 of this thesis have been published in
B. Bellon, A. K. Boukellal, T. Isensee, O. M. Wellborn, K. P. Trumble,
M. J. M. Krane, M. S. Titus, D. Tourret, J. LLorca,
Multiscale prediction of microstructure length scales in metallic alloy casting,
Acta Materialia 207, 116686 (2021),
arXiv:2101.07780 [cond-mat.mtrl-sci]
Results from Secs. 6.3.2 - 6.4 of this thesis have been published in
T. Isensee, D. Tourret,
Convective effects on columnar dendritic solidification – A multiscale dendritic needle network study,
Acta Materialia 234, 118035 (2022),
arXiv:2205.07952 [cond-mat.mtrl-sci
Trace formula for chaotic dielectric resonators tested with microwave experiments
No full textpeer reviewedWe measured the resonance spectra of two stadium-shaped dielectric microwave resonators and tested a semiclassical trace formula for chaotic dielectric resonators proposed by Bogomolny et al. [Phys. Rev. E 78, 056202 (2008)]. We found good qualitative agreement between the experimental data and the predictions of the trace formula. Deviations could be attributed to missing resonances in the measured spectra in accordance with previous experiments [Phys. Rev. E 81, 066215 (2010)]. The investigation of the numerical length pectrum
showed good qualitative and reasonable quantitative agreement with the trace formula. It demonstrated, however, the need for higher-order corrections of the trace formula. The application of a curvature correction to the Fresnel reflection coefficients entering the trace formula yielded better agreement, but deviations remained, indicating the necessity of further investigations
Notícia de llibres
No full textIsensee, J. i Kirchhof, P., Handbuch des Staatsrechts der Bundesrepublik Deutschland. Sosa Wagner, F., La gestión de los servicios públicos locales. Allué Buiza, A., Legitimación de las comunidades autónomas en el recurso de inconstitucionalida
Patriotism in the globalization epoch
No full textThe article deals with patriotism as value and norm of the civil ethics, its substance, basics and functions as well and the transformation of patriotism that have happened through last twenty-thirty years. Patriotism in the soviet society was one of fundamental values of state ideology and social consciousness. Though nowadays national loyalty and patriotism are frequently declared as archaic, irrational or morally inappropriate positions. The author analyses the cause of these changes in the system of values of social consciousness. Relying on works by Z. Bauman, J. Isensee, H. Krings, A. Leist, A.S. Panarin, J. Habermas etc. the author demonstrates that modern democratic society is impossible beyond particular constitutional state as well as without loyalty and social responsibility of its citizens. It is shown two approaches to the basing of patriotism: culture-ontological and individual-ontological. A. Leist describes three methods of the basing of patriotism in the of individualistic alternative: liberal patriotism, value patriotism and particular patriotism
Öffentlichkeitsarbeit der Regierung
No full textShould government be allowed to spend tax payers' money on public relations? If one frames the question that way, the negative answer suggests itself. Yet government communication serves more purposes. These purposes may be analysed in terms of behavioural economics and psychology. In moral suasion, government communication is the governance tool itself. Most other governance tools do not automatically reach their addressees. Appropriate communication is necessary for them to become effective. Finally, government is a legitimate player in political process, and communication to the public is a legitimate element of this process. Specifically, the normatively desirable and the normative problematic aspects can usually not be fully disentangled. Hence, the potential distortion of elections must be outweighed against the governance effect. This paper does so by interpreting governmental public relations as a bundled product. It models the people as the principal, and the political parties running government as the agent. The distortion effect is observable, the governance effect is not. This set-up of the model invites a second-best solution in terms of mechanism design. Government is free to advertise. But advertising is costly in that it generates a handicap at the next elections. This solution is taken as a benchmark for discussing politically more digestible third and forth best alternatives
CONSTITUTION AS HOMELAND. ON THE GERMAN SUPPRESSION OF THE STATE
No full textAutor smatra da je riječ domovina nestala iz političkog jezika i da je zamjenjuje nepolitička riječ: identitet. Ovim se otvara pitanje: što je Nijemcu identitet ako ga država ne može ponuditi? Kao posljedica Hitlerova razdoblja tradicija postaje problem tako da se identitet sada vezuje za ustav. Autor nadalje razmatra posebnosti njemačkog ustavnopravnog sustava kojim je stari državni rezon zamijenjen “ustavnim rezonom”. Na ovaj način patriotizam postaje “ustavni patriotizam”, a ustav domovina. Konsenzus o ustavu koji je bio rezultat općeg pristajanja na antitotalitarizam doveli su u pitanje studenti 1968. godine. Tada je antitotalitarizam zamijenjen antifašizmom, ali se razvila i čitava politička kultura neposluha protiv institucija koja je ustav proglasila “životnom laži sustava”. Oporavak sustava dugo je trajao, ali je njime rehabilitirano državno u ustavnoj državi. Međutim, ovim se ne obnavlja individualnost njemačke državnosti, tj. država ne postaje domovinom. Premda autor smatra da je ovo zastarjelo, ipak naglašava da bi konsenzualna osnova bila šira kad bi Nijemci bili u mogućnosti biti ono što po svojoj povijesti i položaju ustvari jesu, a ne samo ono što bi po ustavu trebali biti.The author argues that the word homeland disappeared from the political language and that it has been replaced by the unpolitical word: identity. This raises a question: what is identity to a German if the state cannot provide it? The consequence of Hitler’s legacy is that the tradition is troublesome so that the identity is now linked with the constitution. The author looks into the idiosyncrasies of the German constitutional/legal system by which the old state thinking has been replaced with the “constitutional thinking”. In this way patriotism becomes “constitutional patriotism”, and the constitution becomes the homeland. The consensus about the constitution – the result of the general acceptance of antitotalitarianism – was challenged by students in 1968, when this antitotalitarianism was replaced by antifascism. At the same time, however, an entire political culture of disobedience against institutions evolved, and declared the constitution the “system’s life’s lie”. The system took a long time to recover, but it rehabilitated the state authority within a constitutional state. Nevertheless, this has not restored the individuality of German statehood i.e. the state does not become the homeland. Although the author is aware that this idea is outmoded, he nevertheless points out that the consensual base would be broader if Germans were allowed to be what they are by their history and their position, and not only what they should be according to the constitution
Protein kinase A activation: Something new under the sun?
No full textThe role of autophosphorylation of the type II regulatory subunit in activation of protein kinase A (PKA) has been a longstanding question. In this issue, Isensee et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201708053) use antibody tools that selectively recognize phosphorylated RII and the catalytic subunit active site to reexamine PKA holoenzyme activation mechanisms in neurons.</jats:p
Pseudoanthidium (Pseudoanthidium) stigmaticorne Dours 1873
No full textPseudoanthidium (Pseudoanthidium) stigmaticorne Dours, 1873 * Distribution: WEST PALAEARCTIC: Maghreb (Ascher & Pickering 2021). Material examined. N. Lebanon: Fehta, El Biara, 1632 m, 18. VII.2018, 1♀, det. Litman J., leg. Boustani M., coll. MBOU. Flower record. Asteraceae: Centaurea pallescens. Genus Rhodanthidium Isensee, 1927 Four species.Published as part of Boustani, Mira, Rasmont, Pierre, Dathe, Holger H., Ghisbain, Guillaume, Kasparek, Max, Michez, Denis, Müller, Andreas, Pauly, Alain, Risch, Stefan, Straka, Jakub, Terzo, Michael, Achter, Xavier Van, Wood, Thomas J. & Nemer, Nabil, 2021, The bees of Lebanon (Hymenoptera: Apoidea: Anthophila), pp. 1-146 in Zootaxa 4976 (1) on page 71, DOI: 10.11646/zootaxa.4976.1.1, http://zenodo.org/record/481901
Age- and gender-specific differences in myocardial gene expression of mice and men
No full textIn the context of the cardiovascular system sex-specific differences have been observed in humans as well as in animal models. The incidence of cardiovascular disease differs significantly between men and women to a number of complex factors. The molecular basis of these differences however is still largely unknown. The aim of this project is to identify sex dimorphisms in the cardiovascular system of healthy mice and humans. Since microarray technology enables the analysis of the expression levels for thousands of genes in a single overnight hybridisation experiment, we determined the age-dependent gene expression profiles of murine whole hearts and human myocardial tissues of both genders. RNA was isolated from whole hearts of eight weeks and eight months old male as well as female mice (n = 6 per group). On the other hand, myocardial samples from <40 years old women (n = 3) and men (n = 4), as well as 50-60 years old women and men (n = 5, respectively) were analysed. RNAs were pooled according to age and gender, cDNAs synthesised and hybridised on microarrays containing either 8,600 mouse or 11,000 human cDNA clones, respectively. We detected genes deregulated between genders in individual experiments common to both ages in mice as well as in humans. Data analysis was also performed by sorting the corresponding deregulated genes into functional categories (i.e. according to their cellular component, gene family membership or molecular function) and several candidate genes were validated using quantitative RT-PCR approaches in individual samples.
Among several differentially expressed genes, we found higher expression levels of natriuretic peptide precursor B (BNP) transcripts in 50-60 years old women. Accordingly, higher plasma levels of BNP, a known marker for left ventricular dysfunction, were reported in earlier clinical studies in older women (Clark et. al. 1990; Wang et al., 2002). Another interesting candidate gene identified as significantly downregulated in <40 years old women was tumor necrosis factor receptor superfamily 11b (TNFRS), encoding osteoprotegerin. Along the same line of evidence, osteoprotegerin has been suggested as a risk factor for progressive atherosclerosis and cardiovascular disease in men and women of the 5th to 8th decades of age (Kiechl et al., 2004).
Altogether, the data obtained is currently being validated and candidate genes analysed in the context of disease pathomechanisms, such as in heart failure
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