Richter H.,University of Hamburg |
Richter H.,University of Amsterdam |
Lieberei R.,University of Hamburg |
Strnad M.,Academy of Sciences of the Czech Republic |
And 6 more authors.
Journal of Experimental Botany | Year: 2012
Polyphenol oxidases (PPOs) are copper-binding enzymes of the plant secondary metabolism that oxidize polyphenols to quinones. Although PPOs are nearly ubiquitous in seed plants, knowledge on their evolution and function in other plant groups is missing. This study reports on the PPO gene family in the moss Physcomitrella patens (Hedw.) B.S.G. asan example for an early divergent plant. The P. patens PPO multigene family comprises 13 paralogues. Phylogenetic analyses suggest that plant PPOs evolved with the colonization of land and that PPO duplications within the monophyletic P. patens paralogue clade occurred after the separation of the moss and seed plant lineages. PPO functionality was demonstrated for recombinant PPO6. P. patens was analysed for phenolic compounds and six substances were detected intracellularly by LC-MS analysis: 4-hydroxybenzoic acid, p-cumaric acid, protocatechuic acid, salicylic acid, caffeic acid, and an ester of caffeic acid. Targeted PPO1 knockout (d|ppo1) plants were generated and plants lacking PPO1 exhibited only ~30% of the wild-type PPO activity in the culture medium, thus suggesting extracellular localization of PPO1, which is in contrast to the mostly plastidic PPO localization in seed plants. Further, d|ppo1 lines formed significantly more gametophores with a reduced areal plant size, which could be related to an increase of endogenously produced cytokinins and indicates an impact of PPO1 on plant development. d|ppo1 plants were less tolerant towards applied 4-methylcatechol compared to the wild type, which suggests a role of extracellular PPO1 in establishing appropriate conditions by the removal of inhibitory extracellular phenolic compounds. ©  The Author.
Feichtinger A.,Vienna University of Technology |
Rachunkova I.,Palack University |
Stanek S.,Palack University |
Weinmuller E.,Vienna University of Technology
Computers and Mathematics with Applications | Year: 2011
In this paper, we show the existence of solutions to a nonlinear singular second order ordinary differential equation, u″(t)=atu′(t) +λf(t,u(t),u′(t)), subject to periodic boundary conditions, where a>0 is a given constant, λ>0 is a parameter, and the nonlinearity f(t,x,y) satisfies the local Carathéodory conditions on [0,T]×ℝ× ℝ. Here, we study the case that a well-ordered pair of lower and upper functions does not exist and therefore the underlying problem cannot be treated by well-known standard techniques. Instead, we assume the existence of constant lower and upper functions having opposite order. Analytical results are illustrated by means of numerical experiments. © 2011 Elsevier Ltd. All rights reserved.
Martn-Fernndez J.A.,University of Girona |
Hron K.,Palack University |
Templ M.,Vienna University of Technology |
Filzmoser P.,Vienna University of Technology |
Palarea-Albaladejo J.,Biomathematics and Statistics Scotland
Computational Statistics and Data Analysis | Year: 2012
The log-ratio methodology represents a powerful set of methods and techniques for statistical analysis of compositional data. These techniques may be used for the estimation of rounded zeros or values below the detection limit in cases when the underlying data are compositional in nature. An algorithm based on iterative log-ratio regressions is developed by combining a particular family of isometric log-ratio transformations with censored regression. In the context of classical regression methods, the equivalence of the method based on additive and isometric log-ratio transformations is proved. This equivalence does not hold for robust regression. Based on Monte Carlo methods, simulations are performed to assess the performance of classical and robust methods. To illustrate the method, a case study involving geochemical data is conducted. © 2012 Elsevier B.V. All rights reserved.
Dobesova Z.,Palack University |
Dobes P.,Palack University
Proceedings of IEEE Symposium on Visual Languages and Human-Centric Computing, VL/HCC | Year: 2012
Contemporary Geographic Information Systems (GIS software) are, in some cases, extended by components for visual programming. These components are used to design a dataflow process. In this poster two examples of components are assessed. These are ModelBuilder in ArcGIS Desktop 10 and the Workflow Designer in AutoCAD Map 3D 2012. In both components for visual programming users are offered a possibility to graphically design steps for spatial data processing. The interfaces, graphic elements and a functionality scope vary greatly between these two components. An assessment is presented from both cognitive as well as usability point of view. AutoCAD Map is based on ideas of Windows Workflow Foundation. ModelBuilder is the solution by Esri Company. Moreover, an output model from ModelBuilder can be converted from graphical sketch to textual scripting language Python. The output Python script can also be used as the starting point for novice programmers. A practical application of a model for batch processing is presented as an example that demonstrates the cartographic generalization-smoothing of vector data for the smaller map scale in ArcGIS ModelBuilder. The following example demonstrates workflow for the spatial function Create Buffer of data in AutoCAD Map Workflow Designer. The presented experiences are based on several years of lecturing at the university. Both visual components are taught within the study program Geoinformatics at Palack University. © 2012 IEEE.
Stank S.,Palack University
Computers and Mathematics with Applications | Year: 2011
We discuss the existence of positive solutions for the singular fractional boundary value problem Dαu+f(t,u,u′, Dμu)=0, u(0)=0, u′(0)=u′(1)=0, where 2<α<3, 0<μ<1. Here Dα is the standard Riemann-Liouville fractional derivative of order α, f is a Carathéodory function and f(t,x,y,z) is singular at the value 0 of its arguments x,y,z. © 2011 Elsevier Ltd. All rights reserved.
Novotna R.,Palack University |
Travnicek Z.,Palack University |
Herchel R.,Palack University
Bioinorganic Chemistry and Applications | Year: 2012
Two SOD-mimic active dimeric Cu(II) chlorido complexes of the compositions [Cuμ-HL 1)lCl(1) and [Cuμ-HL 2)μ-Cl)HL 2)l · 4H (2) involving the cosmetologically relevant cytokinin kinetin (N6-furfuryladenine, HL 1) and its derivative N6-(5-methylfurfuryl)adenine (HL 2) have been synthesized and characterized by elemental analysis, infrared, and electronic spectroscopy, ESI+ mass spectrometry, conductivity and temperature dependence of magnetic susceptibility measurements, and thermogravimetric (TG) and differential thermal (DTA) analyses. The results of these methods, particularly the temperature dependence of magnetic susceptibility, showed the complexes to be dimeric with a strong antiferromagnetic exchange (J = -290 cm -1 for complex 1 and J = -160 cm -1 for 2). The complexes have been identified as auspicious SOD-mimics, as their antiradical activity evaluated by the in vitro SOD-mimic assay resulted in the ICvalues equal to 8.13 μM (1) and 0.71 μM (2). © 2012 Radka Novotná et al.
Karlicky F.,Palack University |
Zboril R.,Palack University |
Otyepka M.,Palack University
Journal of Chemical Physics | Year: 2012
Density functional theory calculations of the electronic structure of graphane and stoichiometrically halogenated graphene derivatives (fluorographene and other analogous graphene halides) show: (i) localized orbital basis sets can be successfully and effectively used for such two-dimensional materials; (ii) several functionals predict that the band gap of graphane is greater than that of fluorographene, whereas HSE06 gives the opposite trend; (iii) HSE06 functional predicts quite good values of band gaps with respect to benchmark theoretical and experimental data; (iv) the zero band gap of graphene is opened by hydrogenation and halogenation and strongly depends on the chemical composition of mixed graphene halides; (v) the stability of graphene halides decreases sharply with increasing size of the halogen atom - fluorographene is stable, whereas graphene iodide spontaneously decomposes. In terms of band gap and stability, the C 2FBr and C 2HBr derivatives seem to be promising materials, e.g., for (opto)electronics applications, because their band gaps are similar to those of conventional semiconductors, and they are expected to be stable under ambient conditions. The results indicate that other fluorinated compounds (C aH bF c and C aF bY c, Y Cl, Br, I) are stable insulators. © 2012 American Institute of Physics.
Andres J.,Palack University |
Rypka M.,Palack University
Nonlinear Analysis: Real World Applications | Year: 2012
Stimulated by the modeling of language structures, we present three adequate constructions of self-similar fractals with a given dimension. A concrete example of an application to quantitative linguistics is then supplied. © 2011 Elsevier Ltd. All rights reserved.
Rachunek L.,Palack University |
Rachunkova I.,Palack University
Nonlinear Analysis: Real World Applications | Year: 2011
The paper deals with the second-order non-autonomous difference equation x(n+1)=x(n)+(n/n+1)2(x(n)-x(n-1)+h2f(x(n))),n ∈ N, where h>0 is a parameter and f is Lipschitz continuous and has three real zeros L0<0
Andres J.,Palack University
Computers and Mathematics with Applications | Year: 2012
On the background of our earlier results concerning the coexistence of infinitely many periodic orbits, we present a new theorem dealing with a large class of one-dimensional multivalued maps with monotone margins and connected values. If a nontrivial (n>1) n-orbit occurs then, according to our theorem, these maps possess a single-valued chaotic selection, on a compact subinterval. © 2012 Elsevier Ltd. All rights reserved.