Band-Limited Localized Parseval Frames and Besov Spaces on Compact Homogeneous Manifolds

In the last decade, methods based on various kinds of spherical wavelet bases have found applications in virtually all areas where analysis of spherical data is required, including cosmology, weather prediction, and geodesy. In particular, the so-called needlets (= band-limited Parseval frames) have become an important tool for the analysis of Cosmic Microwave Background (CMB) temperature data. The goal of the present paper is to construct band-limited and highly localized Parseval frames on general compact homogeneous manifolds. Our construction can be considered as an analogue of the well-known φ-transform on Euclidean spaces.     

Beitrag zur Festigkeitsuntersuchung eingetauchter Körper

Ohne Zusammenfassung     

Adaptive nonparametric regression on spin fiber bundles

The construction of adaptive nonparametric procedures by means of wavelet thresholding techniques is now a classical topic in modern mathematical statistics. In this paper, we extend this framework to the analysis of nonparametric regression on sections of spin fiber bundles defined on the sphere. This can be viewed as a regression problem where the function to be estimated takes as its values algebraic curves (for instance, ellipses) rather than scalars, as usual. The problem is motivated by many important astrophysical applications, concerning, for instance, the analysis of the weak gravitational lensing effect, i.e. the distortion effect of gravity on the images of distant galaxies. We propose a thresholding procedure based upon the (mixed) spin needlets construction recently advocated by Geller and Marinucci (2008, 2010) and Geller et al. (2008, 2009), and we investigate their rates of convergence and their adaptive properties over spin Besov balls.     

Laser-induced retardation of radiation pulses under arbitrary collisional relaxation of low-frequency coherence

The effect of thermal atomic motion in gaseous media on the features of electromagnetically induced transparency is studied. Relatively general and compact analytical expressions are derived for the absorption coefficient and refractive index of a probe wave in the presence of high-power driving radiation that is resonant with respect to the adjacent atomic transition allowing for the relaxation of low-frequency coherence. It is demonstrated that the shape of the spectrum is similar to laser-induced structures in a continuum. This representation of resonances allows the electromagnetically induced transparency to be studied on relatively general assumptions and a significant retardation of radiation pulses and their delays to be demonstrated.     

A low complexity block turbo decoder architecture - [transactions letters]

In this letter we present a low-complexity architecture designed for the decoding of block turbo codes. In particular we simplify the implementation of Pyndiah?s algorithm by not storing any of the concurrent codewords generated by the list decoder.     

The chromatic number and other functions of the lexicographic product

The values of the chromatic and achromatic number, point- and line-connectivity, and point independence number of the lexicographic product of two graphs are examined in relation to the values of the respective parameters on the factor graphs.     

Some Objective and Subjective Differences Between Communication Over Two Videoconferencing Systems

This pilot study examines one feature of a videoconferencing system, namely, the view that conferees get of participants in the other location. The current voice-switched (VS) videoconferencing arrangement was compared to a "continuous presence" (CP) system that provides conferees with the simultaneous view of all participants throughout the meeting. Groups met twice, once over each system; the task in each session involved a problem-solving discussion for which an objective measure of solution quality was available. Questionnaires were administered after each experimental session to assess subjects' opinions about the videoconferencing systems, as well as their perceptions of the nature, style, and outcome of the group interaction. Results based on the objective measure of solution quality show an advantage for CP over VS that is statistically significant. Questionnaire responses indicate large and significant preferences for CP for all items in which the two systems are directly compared. There are also significant differences for some items involving evaluations of a single system at a time; that is, the CP interaction is perceived to have more of the feel of a face-to-face meeting, to be more efficient, and to be somewhat friendlier. These latter differences are attributable, however, to implicit comparisons between the two systems after both have been experienced.