The non-linear evolution of bispectrum from the scale-free N-body simulation

We have accurately measured the bispectrum for four scale-free models of structure formation with the spectral index $n=1$, 0, -1, and -2. The measurement is based on a new method that can effectively eliminate the alias and numerical artifacts, and reliably extend the analysis into the strongly non-linear regime. The work makes use of a set of state-of-the art N-body simulations that have significantly increased the resolution range compared with the previous studies on the subject. With these measured results, we demonstrated that the measured bispectrum depends on the shape and size of $k$-triangle even in the strongly nonlinear regime. It increases with wavenumber and decreases with the spectral index. These results are in contrast with the hypothesis that the reduced bispectrum is a constant in the strongly non-linear regime. We also show that the fitting formula of Scoccimarro & Frieman (1999) does not describe our simulation results well (with a typical error about 40 percent). In the end, we present a new fitting formula for the reduced bispectrum that is valid for $-2 \leq n \leq 0$ with a typical error of 10 percent only.Comment: 33 pages, including 1 table, 14 figures, accepted by Ap

Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies

The binding energies of 29Si, 33S, and 36Cl have been measured with a relative uncertainty $< 0.59 \times 10^{-6}$ using a flat-crystal spectrometer. The unique features of these measurements are 1) nearly perfect crystals whose lattice spacing is known in meters, 2) a highly precise angle scale that is derived from first principles, and 3) a gamma-ray measurement facility that is coupled to a high flux reactor with near-core source capability. The binding energy is obtained by measuring all gamma-rays in a cascade scheme connecting the capture and ground states. The measurements require the extension of precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region, a significant precision measurement challenge. The binding energies determined from these gamma-ray measurements are consistent with recent highly accurate atomic mass measurements within a relative uncertainty of $4.3 \times 10^{-7}$. The gamma-ray measurement uncertainties are the dominant contributors to the uncertainty of this consistency test. The measured gamma-ray energies are in agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure

A cosmological model in Weyl-Cartan spacetime

We present a cosmological model for early stages of the universe on the basis of a Weyl-Cartan spacetime. In this model, torsion $T^{\alpha}$ and nonmetricity $Q_{\alpha \beta}$ are proportional to the vacuum polarization. Extending earlier work of one of us (RT), we discuss the behavior of the cosmic scale factor and the Weyl 1-form in detail. We show how our model fits into the more general framework of metric-affine gravity (MAG).Comment: 19 pages, 5 figures, typos corrected, uses IOP style fil

Lippen-Kiefer-Gaumen-Spalten: Individuelle Analyse der Lippenspalte durch 3-D-Lasertopometrie

Zusammenfassung: Hintergrund: Mit Gipsmodellen und Fotografien ist die dreidimensionale Analyse einer Lippen-Kiefer-Gaumen-Spalte meist nur unzureichend möglich. Ziel der vorliegenden Studie war es daher, die 3-D-Lasertopometrie auf ihre Anwendbarkeit zur dreidimensionalen Weichgewebserfassung bei Patienten mit Lippen-Kiefer-Gaumen-Spalten zu testen. Patienten und Methode: Bei 20 Patienten (3-35 Jahre), die eine einseitige, nicht operierte Lippen-, Lippen-Kiefer- oder Lippen-Kiefer-Gaumen-Spalte aufwiesen, wurde mit einem 3-D-Laserscanner die Gesichtsoberfläche prä- und postoperativ dreidimensional erfasst. Die dabei erzeugten digitalen Datensätze wurden in einer virtuellen Umgebung metrisch analysiert und anhand von Quotienten größenunabhängig wiedergegeben. Sie dienten der Auswahl der Operationstechnik und der Beurteilung des Operationsergebnisses. Ergebnisse: Mit dem 3-D-Laserscanner wurden 3-D-Oberflächen guter Qualität erstellt, die sich im Millimeterbereich ausmessen ließen. Die dreidimensionale Spaltmorphologie konnte in den Datensätzen reproduzierbar mit Landmarks versehen und vermessen werden. Auch die postoperative Symmetrie ließ sich so kontrollieren und objektivieren. Als nachteilig erwiesen sich die relativ lange Messzeit und die Notwendigkeit zur Kombination mehrerer Ansichten. Schlussfolgerung: Das vorgestellte 3-D-Laserverfahren ermöglicht eine präzise dreidimensionale Weichteilanalyse der Lippen- und Nasenregion bei Spaltpatienten. Es eignet sich jedoch nur bedingt für lebhafte Säuglinge und unkooperative Patiente

Integration of D-dimensional 2-factor spaces cosmological models by reducing to the generalized Emden-Fowler equation

The D-dimensional cosmological model on the manifold $M = R \times M_{1} \times M_{2}$ describing the evolution of 2 Einsteinian factor spaces, $M_1$ and $M_2$, in the presence of multicomponent perfect fluid source is considered. The barotropic equation of state for mass-energy densities and the pressures of the components is assumed in each space. When the number of the non Ricci-flat factor spaces and the number of the perfect fluid components are both equal to 2, the Einstein equations for the model are reduced to the generalized Emden-Fowler (second-order ordinary differential) equation, which has been recently investigated by Zaitsev and Polyanin within discrete-group analysis. Using the integrable classes of this equation one generates the integrable cosmological models. The corresponding metrics are presented. The method is demonstrated for the special model with Ricci-flat spaces $M_1,M_2$ and the 2-component perfect fluid source.Comment: LaTeX file, no figure

Toda chains with type A_m Lie algebra for multidimensional m-component perfect fluid cosmology

We consider a D-dimensional cosmological model describing an evolution of Ricci-flat factor spaces, M_1,...M_n (n > 2), in the presence of an m-component perfect fluid source (n > m > 1). We find characteristic vectors, related to the matter constants in the barotropic equations of state for fluid components of all factor spaces. We show that, in the case where we can interpret these vectors as the root vectors of a Lie algebra of Cartan type A_m=sl(m+1,C), the model reduces to the classical open m-body Toda chain. Using an elegant technique by Anderson (J. Math. Phys. 37 (1996) 1349) for solving this system, we integrate the Einstein equations for the model and present the metric in a Kasner-like form.Comment: LaTeX, 2 ps figure

User-modelled ambient feedback for self-regulated learning

A fundamental objective of human-computer interaction research is to make systems that are seamlessly integrated into daily life activities. Hence, the challenge is not only to make information available to people at any time, at any place, and in any form, but specifically to say the right thing at the right time in the right way. On the other hand, the proliferation of sensor technology is facilitating the scaffolding and customization of smart learning environments. This manuscript presents an ecology of resources comprising NFC, BLE and Arduino technology, orchestrated in the context of a learning environment to provide smoothly integrated feedback via ambient displays. This ecology is proposed as a suitable solution for self-regulated learning, providing support for setting goals, setting aside time to learn, tracking study time and monitoring the progress. Hereby, the ecology is described and intriguing research questions are introduced

Anharmonic double-phonon excitations in the interacting boson model

Double-$\gamma$ vibrations in deformed nuclei are analyzed in the context of the interacting boson model. A simple extension of the original version of the model towards higher-order interactions is required to explain the observed anharmonicities of nuclear vibrations. The influence of three- and four-body interactions on the moments of inertia of ground- and $\gamma$-bands, and on the relative position of single-$\gamma$ and double-$\gamma$ bands is studied in detail. As an example of a realistic calculation, spectra and transitions of the highly $\gamma$-anharmonic nuclei $^{164}$Dy, $^{166}$Er, and $^{168}$Er are interpreted in this approach.Comment: 38 pages, TeX (ReVTeX). 15 ps figures. Submitted to Phys. Rev.

Cosmological perturbations in the inflationary Universe

Previously defined covariant and gauge-invariant perturbation variables, representing, e.g., the fractional spatial energy density gradient on hypersurfaces of constant expansion, are used to simplify the linear perturbation analysis of a classical scalar field. With the help of conserved quantities on large scales we establish an exact first-order relation between comoving fluid energy density perturbations at `reentry' into the horizon and corresponding scalar field energy density perturbations at the first Hubble scale crossing during an early de Sitter phase of a standard inflationary scenario.Comment: 11 pages, Revtex, to appear in PR