Leibniz University of Hanover

About: Leibniz University of Hanover is a education organization based out in Hanover, Niedersachsen, Germany. It is known for research contribution in the topics: Finite element method & Computer science. The organization has 14283 authors who have published 29845 publications receiving 682152 citations.

Mordell-Weil Lattices

Abstract: In this chapter, we give the definition of Mordell–Weil lattice (in Sect. 6.5). First, we bring together the concepts from Chaps. 4 and 5 in order to gain a better understanding of the Neron–Severi lattice of an elliptic surface. This will lead to the announced notion of Mordell–Weil lattice which will be studied in detail in this chapter, but also throughout the remainder of this book.

Two-photon fabrication

Abstract: Two-photon polymerization is a 3D nanoscale manufacturing tool that offers great potential for rapid prototyping and the manufacture of photonic devices, tissue scaffolds and biomechanical parts.

Substances released from dental resin composites and glass ionomer cements.

Abstract: An increasing number of cavities in the primary and permanent dentition is restored with tooth-colored materials, especially dental resin composites or glass ionomer cements. Several investigations have revealed that various components are segregated from different composite filling materials into an aqueous environment after polymerization. Most organic substances can be extracted from a set resin by organic solvents (methanol, tetrahydrofuran, ethanol). Furthermore, in most studies, the co-monomer TEG-DMA has been identified as the main compound released from polymerized resin composites into aqueous media. However, small quantities of the monomers (Bis-GMA, UDMA) and other co-monomers, as well as additives, may also be released into water. Very little data have been published about substances released from various types of glass ionomer cements (GIC), except the liberation of fluoride. Erosion studies have revealed that there is a considerable disintegration of GICs at lower pH-values. However, the nature of the eroded substances has not yet been clarified. Altogether, the data presented in this review indicate that information is comparably scarce for resin composites and GICs in comparison to the rich amount of knowledge concerning amalgams. Therefore, further studies are necessary to determine quality and quantity of substances segregated from resin composites and GICs.

Microwave quantum logic gates for trapped ions

Abstract: Control over physical systems at the quantum level is important in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom can be coherently manipulated with laser light. Similar control is difficult to achieve with radio-frequency or microwave radiation: the essential coupling between internal degrees of freedom and motion requires significant field changes over the extent of the atoms' motion, but such changes are negligible at these frequencies for freely propagating fields. An exception is in the near field of microwave currents in structures smaller than the free-space wavelength, where stronger gradients can be generated. Here we first manipulate coherently (on timescales of 20 nanoseconds) the internal quantum states of ions held in a microfabricated trap. The controlling magnetic fields are generated by microwave currents in electrodes that are integrated into the trap structure. We also generate entanglement between the internal degrees of freedom of two atoms with a gate operation suitable for general quantum computation; the entangled state has a fidelity of 0.76(3), where the uncertainty denotes standard error of the mean. Our approach, which involves integrating the quantum control mechanism into the trapping device in a scalable manner, could be applied to quantum information processing, simulation and spectroscopy.

The Parallelized Large-Eddy Simulation Model (PALM) version 4.0 for atmospheric and oceanic flows: model formulation, recent developments, and future perspectives

Abstract: . In this paper we present the current version of the Parallelized Large-Eddy Simulation Model (PALM) whose core has been developed at the Institute of Meteorology and Climatology at Leibniz Universitat Hannover (Germany). PALM is a Fortran 95-based code with some Fortran 2003 extensions and has been applied for the simulation of a variety of atmospheric and oceanic boundary layers for more than 15 years. PALM is optimized for use on massively parallel computer architectures and was recently ported to general-purpose graphics processing units. In the present paper we give a detailed description of the current version of the model and its features, such as an embedded Lagrangian cloud model and the possibility to use Cartesian topography. Moreover, we discuss recent model developments and future perspectives for LES applications.