Daniel Roth

Detection of the millimeter wave spectra of the weakly bound complexes 3He–CO and 4He–CO

For the first time, millimeter wave absorption spectra of the van der Waals complexes 3He–CO and 4He–CO were detected in a supersonic jet. Altogether four rotational transitions of 3He–CO and six rotational transitions of 4He–CO were recorded between 110 GHz and 127 GHz with an intracavity spectrometer based on the millimeter wave generator, called OROTRON. The obtained results were included in a global fit together with previously known data enabling a more precise determination of the energy levels of the 3He–CO and 4He–CO complexes. In extremely cold, dark, and dense interstellar clouds the He–CO complex may have astrophysical relevance.

The use of virtual characters to assess and train non-verbal communication in high-functioning autism.

High-functioning autism (HFA) is a neurodevelopmental disorder, which is characterized by life-long socio-communicative impairments on the one hand and preserved verbal and general learning and memory abilities on the other. One of the areas where particular difficulties are observable is the understanding of non-verbal communication cues. Thus, investigating the underlying psychological processes and neural mechanisms of non-verbal communication in HFA allows a better understanding of this disorder, and potentially enables the development of more efficient forms of psychotherapy and trainings. However, the research on non-verbal information processing in HFA faces several methodological challenges. The use of virtual characters (VCs) helps to overcome such challenges by enabling an ecologically valid experience of social presence, and by providing an experimental platform that can be systematically and fully controlled. To make this field of research accessible to a broader audience, we elaborate in the first part of the review the validity of using VCs in non-verbal behavior research on HFA, and we review current relevant paradigms and findings from social-cognitive neuroscience. In the second part, we argue for the use of VCs as either agents or avatars in the context of “transformed social interactions.” This allows for the implementation of real-time social interaction in virtual experimental settings, which represents a more sensitive measure of socio-communicative impairments in HFA. Finally, we argue that VCs and environments are a valuable assistive, educational and therapeutic tool for HFA.

Discovery of the rotational spectrum of the weakly bound complex CO–H2

Rotational transitions of the CO–H2 van der Waals complex have been measured between 108 and 125 GHz in a supersonic jet. Three absorption lines were recorded and assigned as belonging to CO–paraH2 with a new highly sensitive intracavity spectrometer based on the millimeter wave generator, called OROTRON. The results provide confirmation of the recent infrared data of McKellar at 4.7 μm, enabling a more precise determination of the energies of the rotational levels with different parity in the vibrational ground state. The measured millimeter wave transitions provide precise frequencies for an astronomical search of CO–paraH2.

The CO dimer millimeter wave spectrum: Detection of tunneling transitions

A portion of the CO dimer millimeter wave absorption spectrum has been studied by using our highly sensitive intracavity-jet OROTRON spectrometer in the frequency range from 131 to 174 GHz. By varying the CO concentration in the Ne/CO gas mixture feeding the supersonic jet expansion, the effective temperature of the beam could be changed, revealing a correlation between the observed line intensity and the relative energy of the respective lower state energy levels. Using this temperature dependence and the technique of combination differences together with the data from the infrared study of Brookes and McKellar [J. Chem. Phys. 111, 7321 (1999)], out of over 200 observed transitions, a total of 19 lines could be assigned. All assigned millimeter-wave transitions are tunneling transitions. They belong to four subbands, which connect seven lower energy levels with A+ symmetry to ten previously unknown upper energy levels with A− symmetry. The A+ and A− separation signifies the tunneling splitting of the CO ...

Unequivocal laboratory detection of CO dimer transitions in the millimeter wave region

Abstract CO dimer transitions were found for the first time in the millimeter wave region, i.e. in the frequency range from 142 to 172 GHz. An isotopic test was performed to authenticate the origin of the transition to the CO dimer. At present the millimeter wave data are not yet sufficient to secure a firm assignment. A brief overview of the history of this complex is given.

The weakly bound complex CH4-H2: Observation and analysis of infrared spectra in the 350 and 1311 cm−1 regions

Infrared spectra of the weakly bound van der Waals complex CH4-paraH2 have been observed and analyzed for the first time. Measurements were made using a long-path (160–180 m) low-temperature (61–92 K) absorption cell which was probed with a Fourier transform spectrometer and a tunable diode laser. The partly resolved spectrum accompanying the S0(0) pure rotational transition of H2 around 350 cm−1 was analyzed in terms of an approximate model to obtain the rotational and centrifugal distortion constants of the complex in its ground state. The high resolution spectrum accompanying the R(0) transition of the ν4 fundamental band of CH4 near 1311 cm−1 was assigned in detail and analyzed using the Coriolis model used previously for analogous spectra of methane–rare gas complexes. The effective intermolecular separation and dissociation energy of the complex in its ground state were determined to be about 4.12 A and 28 cm−1, respectively.

Avatar realism and social interaction quality in virtual reality

In this paper, we describe an experimental method to investigate the effects of reduced social information and behavioral channels in immersive virtual environments with full-body avatar embodiment. We compared physical-based and verbal-based social interactions in real world (RW) and virtual reality (VR). Participants were represented by abstract avatars that did not display gaze, facial expressions or social cues from appearance. Our results show significant differences in terms of presence and physical performance. However, differences in effectiveness in the verbal task were not present. Participants appear to efficiently compensate for missing social and behavioral cues by shifting their attentions to other behavioral channels.

Hybrid Avatar-Agent Technology – A Conceptual Step Towards Mediated “Social” Virtual Reality and its Respective Challenges

Abstract Driven by large industry investments, developments of Virtual Reality (VR) technologies including unobtrusive sensors, actuators and novel display devices are rapidly progressing. Realism and interactivity have been postulated as crucial aspects of immersive VR since the naissance of the concept. However, today’s VR still falls short from creating real life-like experiences in many regards. This holds particularly true when introducing the “social dimension” into the virtual worlds. Apparently, creating convincing virtual selves and virtual others and conveying meaningful and appropriate social behavior still is an open challenge for future VR. This challenge implies both, technical aspects, such as the real-time capacities of the systems, but also psychological aspects, such as the dynamics of human communication. Our knowledge of VR systems is still fragmented with regard to social cognition, although the social dimension is crucial when aiming at autonomous agents with a certain social background intelligence. It can be questioned though whether a perfect copy of real life interactions is a realistic or even meaningful goal of social VR development at this stage. Taking into consideration the specific strengths and weaknesses of humans and machines, we propose a conceptual turn in social VR which focuses on what we call “hybrid avatar-agent systems”. Such systems are required to generate i) avatar mediated interactions between real humans, taking advantage of their social intuitions and flexible communicative skills and ii) an artificial social intelligence (AIS) which monitors, and potentially moderates or transforms ongoing virtual interactions based on social signals, such as performing adaptive manipulations of behavior in intercultural conversations. The current article sketches a respective base architecture and discusses necessary research prospects and challenges as a starting point for future research and development.

Millimeter wave spectroscopy in a pulsed supersonic slit nozzle discharge

Abstract A Doppler-free technique for direct absorption spectroscopy of rotationally cold molecular ions in the millimeter wave range is presented. The method uses a double modulation technique, based on a simultaneous modulation of a frequency doubled microwave sweeper and a pulsed slit nozzle, incorporating a discharge in a high-pressure supersonic expansion. The performance is demonstrated with the observation of the hyperfine structure of the J =2←1 pure rotational transition of N 2 H + . Further perspectives of the method are discussed.

FakeMi: a fake mirror system for avatar embodiment studies

This paper introduces a fake mirror system as a research tool to study the effect of avatar embodiment with non-visually immersive virtual environments. The system combines marker-less face and body tracking to animate the individual avatars seen in a stereoscopic display with a correct perspective projection. The display dimensions match typical dimensions of a real physical mirror and the animated avatars are rendered based on a geometrically correct reflection as expected from a real mirror including correct body and face animations. The first evaluation of the system reveals the high acceptance of the setup as well as a convincing illusion of a real mirror with different types of avatars.