Computation of forces in strongly nonlinear magnetic fields using higher-order eggshell algorithm

A novel version of the eggshell-based procedure for numerical computation of magnetic forces and torques acting on ferromagnetic bodies in highly nonlinear magnetic fields is presented. The procedure works with a fully adaptive higher-order finite element method developed for years in our research group, that is implemented in own code Agros2D and library Hermes. The power of the methodology and both codes is demonstrated on the solution of two typical examples: computation of the static characteristic of a magnetic actuator and torque characteristic of a flux-switched permanent-magnet machine. The results obtained are compared with data calculated by several other available codes

Continuous laser hardening with induction pre-heating

A novel way of continuous surface hardening of steel bodies by a laser beam is modeled. This heat treatment is supplemented with pre-heating of the hardened parts by a classic inductor in order to reduce the temperature gradients and subsequent mechanical stresses in the processed material. The mathematical model of the process is solved numerically in 3D and the solution respects all important nonlinearities (a saturation curve of the hardened steel and temperature dependences of its physical properties). The methodology is illustrated with a typical example, whose results are presented and discussed

Physical mapping integrated with syntenic analysis to characterize the gene space of the long arm of wheat chromosome 1A

Background: Bread wheat (Triticum aestivum L.) is one of the most important crops worldwide and its production faces pressing challenges, the solution of which demands genome information. However, the large, highly repetitive hexaploid wheat genome has been considered intractable to standard sequencing approaches. Therefore the International Wheat Genome Sequencing Consortium (IWGSC) proposes to map and sequence the genome on a chromosome-by-chromosome basis. Methodology/Principal Findings: We have constructed a physical map of the long arm of bread wheat chromosome 1A using chromosome-specific BAC libraries by High Information Content Fingerprinting (HICF). Two alternative methods (FPC and LTC) were used to assemble the fingerprints into a high-resolution physical map of the chromosome arm. A total of 365 molecular markers were added to the map, in addition to 1122 putative unique transcripts that were identified by microarray hybridization. The final map consists of 1180 FPC based or 583 LTC based contigs. Conclusions/Significance: The physical map presented here marks an important step forward in mapping of hexaploid bread wheat. The map is orders of magnitude more detailed than previously available maps of this chromosome, and the assignment of over a thousand putative expressed gene sequences to specific map locations will greatly assist future functional studies. This map will be an essential tool for future sequencing of and positional cloning within chromosome 1A

Slowly rotating voids in cosmology

We consider a spacetime consisting of an empty void separated from an almost Friedmann-Lema\^\i tre-Robertson-Walker (FLRW) dust universe by a spherically symmetric, slowly rotating shell which is comoving with the cosmic dust. We treat in a unified manner all types of the FLRW universes. The metric is expressed in terms of a constant characterizing the angular momentum of the shell, and parametrized by the comoving radius of the shell. Treating the rotation as a first order perturbation, we compute the dragging of inertial frames as well as the apparent motion of distant stars within the void. Finally, we discuss, in terms of in principle measurable quantities, 'Machian' features of the model.Comment: 21 pages, 5 figures, REVTex, accepted for publication in Class.Quant.Gravit

Gravity on de-Sitter 3-Brane, Induced Einstein-Hilbert Term and Massless Gravitons

We study the extensions of DGP model which are described by five-dimensional Einstein gravity coupled covariantly to 3-brane with induced gravity term and consider warped D=4 de Sitter background field solutions on the brane. The case with included D=5 AdS cosmological term is also considered. Following background field method we obtain the field equations described by the Lagrangean terms bilinear in gravitational field. In such a linear field approximation on curved dS background we calculate explicitly the five-dimensional massive terms as well as the mass-like ones on the brane. We investigate the eigenvalue problem of Schr\"{o}dinger-like equation in fifth dimension for graviton masses and discuss the existence of massless as well as massive graviton modes in the bulk and on the brane without and with induced gravity.Comment: LaTeX 26 pages, the version which appears in Class. Quant. Gra

Computer simulation of rod-coil block copolymers and tetrapod,polymer mixtures

In this thesis I present a new coarse-grained model suitable to investigate the phase behavior of rod-coil block copolymers on mesoscopic length scales. In this model the rods are represented by hard spherocylinders, whereas the coil block consists of interconnected beads. The interactions between the constituents are based on local densities. This facilitates an efficient Monte-Carlo sampling of the phase space. I verify the applicability of the model and the simulation approach by means of several examples. I treat pure rod systems and mixtures of rod and coil polymers. Then I append coils to the rods and investigate the role of the different model parameters. Furthermore, I compare different implementations of the model. I prove the capability of the rod-coil block copolymers in our model to exhibit typical micro-phase separated configurations as well as extraordinary phases, such as the wavy lamellar state, percolating structuresrnand clusters. Additionally, I demonstrate the metastability of the observed zigzag phase in our model. A central point of this thesis is the examination of the phase behavior of the rod-coil block copolymers in dependence of different chain lengths and interaction strengths between rods and coil. The observations of these studies are summarized in a phase diagram for rod-coil block copolymers. Furthermore, I validate a stabilization of the smectic phase with increasing coil fraction.rnIn the second part of this work I present a side project in which I derive a model permitting the simulation of tetrapods with and without grafted semiconducting block copolymers. The effect of these polymers is added in an implicit manner by effective interactions between the tetrapods. While the depletion interaction is described in an approximate manner within the Asakura-Oosawa model, the free energy penalty for the brush compression is calculated within the Alexander-de Gennes model. Recent experiments with CdSe tetrapods show that grafted tetrapods are clearly much better dispersed in the polymer matrix than bare tetrapods. My simulations confirm that bare tetrapods tend to aggregate in the matrix of excess polymers, while clustering is significantly reduced after grafting polymer chains to the tetrapods. Finally, I propose a possible extension enabling the simulation of a system with fluctuating volume and demonstrate its basic functionality. This study is originated in a cooperation with an experimental group with the goal to analyze the morphology of these systems in order to find the ideal morphology for hybrid solar cells.In dieser Arbeit präsentiere ich ein neues vergröbertes Modell, das geeignet ist das Phasenverhalten von Rod-Coil-Blockcopolymeren auf mesoskopischen Längenskalen zu untersuchen. In diesem Modell werden die Rods durch harte Spherozylinder dargestellt, während der Coilblock aus miteinander verbundenen Perlen besteht. Die Wechselwirkungen zwischen den Bestandteilen basiert auf lokalen Dichten. Dies ermöglicht ein effizientes Monte-Carlo-Sampling des Phasenraumes. Ich überprüfe die Anwendbarkeit des Modells und des Simulationsansatzes anhand mehrerer Beispiele. Ich behandle reine Rodsystemen und Mischungen von Rod und Coil Polymeren. Dann füge ich Coils an die Rods an und untersuche die Rolle der verschiedenen Modellparameter. Des Weiteren vergleiche ich verschiedene Umsetzungen des Modells. Ich belege die Fähigkeit der Rod-Coil-Blockcopolymere in unserem Modell typische mikrophasenseparierte Konfigurationen, sowie außergewöhnliche Phasen wie den wellenförmig lamellären Zustand, perkoliernde Strukturen und Cluster aufzuweisen. Darüber hinaus zeige ich die Metastabilität der beobachteten Zickzack-Phase in unserem Modell. Ein zentraler Punkt dieser Arbeit ist die Untersuchung des Phasenverhaltens der Rod-Coil-Blockcopolymere in Abhängigkeit unterschiedlicher Kettenlängen und Wechselwirkungsstärken zwischenrnRods und Coils. Die Beobachtungen dieser Studien sind in einem Phasendiagramm für Rod-Coil-Blockcopolymere zusammengefasst. Darüber hinaus bestätige ich eine Stabilisierung der smektischen Phase mit zunehmendem Coil Anteil.rnIm zweiten Teil dieser Arbeit präsentiere ich ein Nebenprojekt, in dem ich ein Modell herleite, das die Simulation von Tetrapoden mit und ohne aufgepfropfte halbleitende Blockcopolymere ermöglicht. Die Wirkung dieser Polymere wird auf implizite Weise durch effektive Wechselwirkungen zwischen den Tetrapoden hinzugefügt. Während die Verarmungs-Wechselwirkung näherungsweise im Asakura-Oosawa Modell beschrieben wird, errechnet sich die freie Energie Strafe für die Kompression der Bürsten innerhalb des Alexander-de Gennes Modells. Jüngste Experimente mit CdSe Tetrapoden zeigen, dass gepfropfte Tetrapoden eindeutig viel besser in der Polymermatrix dispergiert sind als blanke Tetrapoden. Meine Simulationen bestätigen, dass blanke Tetrapoden dazu neigen in der Matrix überschüssiger Polymere zu aggregieren, während die Clusterbildung deutlich reduziert wird, wenn Polymerketten auf die Tetrapoden gepfropft werden. Schließlich schlage ich eine mögliche Erweiterung vor, welche die Simulation von Systemen mit schwankendem Volumen ermöglicht und demonstriere ihre grundlegende Funktionalität. Diese Studie ist in Kooperation mit einer experimentellen Arbeitsgruppe mit dem Ziel entstanden, die Morphologie dieser Systeme zu analysieren, um die ideale Morphologie für Hybrid-Solarzellen zu finden

DArT whole genome profiling provides insights on the evolution and taxonomy of edible Banana (Musa spp.)

Background and Aims: Dessert and cooking bananas are vegetatively propagated crops of great importance for both the subsistence and the livelihood of people in developing countries. A wide diversity of diploid and triploid cultivars including AA, AB, AS, AT, AAA, AAB, ABB, AAS and AAT genomic constitutions exists. Within each of this genome groups, cultivars are classified into subgroups that are reported to correspond to varieties clonally derived from each other after a single sexual event. The number of those founding events at the basis of the diversity of bananas is a matter of debate. Methods: We analysed a large panel of 575 accessions, 94 wild relatives and 481 cultivated accessions belonging to the section Musa with a set of 498 DArT markers previously developed. Key Results: DArT appeared successful and accurate to describe Musa diversity and help in the resolution of cultivated banana genome constitution and taxonomy, and highlighted discrepancies in the acknowledged classification of some accessions. This study also argues for at least two centres of domestication corresponding to South-East Asia and New Guinea, respectively. Banana domestication in New Guinea probably followed different schemes that those previously reported where hybridization underpins the emergence of edible banana. In addition, our results suggest that not all wild ancestors of bananas are known, especially in M. acuminata subspecies. We also estimate the extent of the two consecutive bottlenecks in edible bananas by evaluating the number of sexual founding events underlying our sets of edible diploids and triploids, respectively. Conclusions: The attribution of clone identity to each sample of the sets allowed the detection of subgroups represented by several sets of clones. Although morphological characterization of some of the accessions is needed to correct potentially erroneous classifications, some of the subgroups seem polyclonal