Function estimation with locally adaptive dynamic models

We present a nonparametric Bayesian method for fitting unsmooth and highly oscillating functions, which is based on a locally adaptive hierarchical extension of standard dynamic or state space models. The main idea is to introduce locally varying variances in the state equations and to add a further smoothness prior for this variance function. Estimation is fully Bayesian and carried out by recent MCMC techniques. The whole approach can be understood as an alternative to other nonparametric function estimators, such as local or penalized regression with variable bandwidth or smoothing parameter selection. Performance is illustrated with simulated data, including unsmooth examples constructed for wavelet shrinkage, and by an application to sales data. Although the approach is developed for classical Gaussian nonparametric regression, it can be extended to more complex regression problems

Anapoles in Free-Standing III-V Nanodisks Enhancing Second-Harmonic Generation

Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: lack of energy losses and invisibility to the propagating electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, where a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to create nanoantennas by slicing III-V nanowires into standing disks using focused ion beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure to design and produce disk nanoantennas from nanowires become one of standard approaches to fabricate controlled chains of standing nanodisks with different designs and configurations. These chains can be an essential building blocks for new types of lasers and sensors with low power consumption

Functional compounds of einkorn and emmer genotypes

Three einkorn and two emmer genotypes were analysed for concentration of microelements (Fe, Zn and Se) and lipid soluble antioxidants (α-tocopherol, α-tocotrienol and β-carotene). A diversity was observed in micronutrient content, but most of the genotypes have significantly higher trace element and antioxidant contents than the control wheat variety. The emmer genotypes contain lower Fe and β-carotene concentration than einkorn genotypes. The einkorn genotypes have significant higher antioxidant content than the wheat control. On average einkorn has more than three times more β-carotene than the wheat variety. Our results are useful for species/variety choice in functional food production not only for organic but also for conventional farmers, who have/want to operate under low input conditions, especially in Central Europe

The magnetic environment in the central region of nearby galaxies

The central regions of galaxies harbor some of the most extreme physical phenomena, including dense stellar clusters, non-circular motions of molecular clouds and strong and pervasive magnetic field structures. In particular, radio observations have shown that the central few hundred parsecs of our Galaxy has a striking magnetic field configuration. It is not yet clear whether these magnetic structures are unique to our Milky Way or a common feature of all similar galaxies. Therefore, we report on (a) a new radio polarimetric survey of the central 200 pc of the Galaxy to better characterize the magnetic field structure and (b) a search for large-scale and organized magnetized structure in the nuclear regions of nearby galaxies using data from the Very Large Array (VLA) archive. The high angular resolution of the VLA allows us to study the central 1 kpc of the nearest galaxies to search for magnetized nuclear features similar to what is detected in our own Galactic center. Such magnetic features play a important role in the nuclear regions of galaxies in terms of gas transport and the physical conditions of the interstellar medium in this unusual region of galaxies.Comment: 8 pages; Proceedings for "The Universe under the Microscope" (AHAR 2008), held in Bad Honnef (Germany) in April 2008, to be published in Journal of Physics: Conference Series by Institute of Physics Publishing, R. Schoedel, A. Eckart, S. Pfalzner, and E. Ros (eds.

Validation of Geant4-based Radioactive Decay Simulation

Radioactive decays are of concern in a wide variety of applications using Monte-Carlo simulations. In order to properly estimate the quality of such simulations, knowledge of the accuracy of the decay simulation is required. We present a validation of the original Geant4 Radioactive Decay Module, which uses a per-decay sampling approach, and of an extended package for Geant4-based simulation of radioactive decays, which, in addition to being able to use a refactored per-decay sampling, is capable of using a statistical sampling approach. The validation is based on measurements of calibration isotope sources using a high purity Germanium (HPGe) detector; no calibration of the simulation is performed. For the considered validation experiment equivalent simulation accuracy can be achieved with per-decay and statistical sampling