Arrays of atoms trapped in optical lattices are appealing as storage media for photons, since motional dephasing of the atoms is eliminated. The regular lattice is also associated with band structure in the dispersion experienced by incident photons. Here we study the influence of this band structure on the efficiency of quantum memories based on electromagnetically induced transparency (EIT) a...

We present direct evidence of dynamical diffraction of x rays from a quasicrystal. High-resolution x-raydiffraction measurements of the Al-Pd-Mn face-centered icosahedral quasicrystal were performed, revealing a mosaic full width at half maximum of less than 0.001°. In a second experiment, the anomalous transmission of x rays (the Borrmann effect) was observed. These measurements show that near...

The precipitation of lithium dissolved in germanium crystals and the re-solution of the pre­ cipitates during heating has been studied by means of anomalous transmission of x-rays. The effec­ tive absorption coefficient depends sensitively on the spacial distribution of lithium interstitials, and is enhanced enormously if pair correlations increase, as is the case during clustering. On the basi...

This document reports in brief the findings of a study conducted to observe the relationship between a sense of presence and team training in decision making in dynamic high risk environments. A simple desktop virtual game environment is used to explore the possibility that, in this context, such semi immersive dynamic virtual environment (VE) could be used to achieve a sense of presence suffic...

This article describes a series of experiments which were carried out to measure the sense of presence in auditory virtual environments. Within the study a comparison of self-created signals to signals created by the surrounding environment is drawn. Furthermore, it is investigated if the room characteristics of the simulated environment have consequences on the perception of presence during vo...

A sense of spatial presence as a feeling of “being there” is an important part of the virtual experience. Navigation is a fundamental task in virtual environments and the specific navigation methods that are employed influence a user’s sense of presence. In this paper we investigate how different metaphors for vertical navigation impact spatial presence. We introduce a new elevator metaphor for...

SEPTEMBER 2004 AMERICAN METEOROLOGICAL SOCIETY | W hen radars first came into operation during the late 1930s, they were not expected to detect targets much beyond the geometrical horizon. These early radars, operating at a wavelength of 13 m, generally met expectations. As new radars were rapidly developed, operating at shorter and shorter wavelengths for better target detection, observations ...

Thesis for the degree of Doctor of Technology, to be presented with due permission for public examination and criticism in the Seminar Room Abstract This investigation has been carried out at the Royal Institute of Technology (KTH) in Stockholm. The main goal has been to investigate the factors determining the production of a sense of presence and reality in video mediated communication. Presen...

In previous work, we have found significant differences in the accuracy with which people make initial spatial judgments in different types of head-mounted, display-based immersive virtual environments (IVEs; Phillips, Interrante, Kaeding, Ries, & Anderson, 2010). In particular, we have found that people tend to less severely underestimate egocentric distances in a virtual environment that is a...

This paper focuses on the user’s perception of virtual agents embedded in real and virtual worlds. In particular, we analyze the perception of spatial relations and the perception of coexistence. For this purpose, we measure the user’s voice compensation which is one of the human automatic behaviors to their surrounding environment. The results of our evaluation study reveal that people compens...