Dust grain properties were investigated in two very different Galactic environments: the interstellar medium and an exoplanetary system. Two sounding rocket missions were developed to study these regions. Wide-field observations of the Orion OB stellar association were performed in the far-ultraviolet using the Spectrograph for Photometric Imaging with Numeric Reconstruction (SPINR) sounding rocket. These observations reveal the diffuse signature of starlight scattering off interstellar dust grains. The spectral-imaging data were used along with a three-dimensional radiative transfer model to measure the dust scattering parameters: the grain albedo (a) and the scattering asymmetry (g). The measured parameters are consistent with previous measurements made toward Orion. A sharp increase in albedo was measured at 〜1330 A. This feature is not explained by current grain models. The constructed three-dimensional model of Orion includes a two-component dust distribution. The foreground distribution is responsible for the small amount of visible reddening measured toward the bright stars in the Orion constellation.The background distribution represents the Orion Molecular Cloud, which dominates observations of dust emission in the infrared. This model was used to show that backscattered light from the molecular cloud alone cannot produce the observed scattered light distribution. The foreground dust, though optically thin in the visible, significantly contributes to the scattered light in the far-ultraviolet. This suggests that observations of Orion in the infrared and far-ultraviolet may probe entirely different dust populations. The Planetary Imaging Concept Testbed Using a Rocket Experiment (PICTURE) sounding rocket was developed to characterize dust grains in the nearby Epsilon Eridani exoplanetary system. This is a young, dusty system with a Jupiter-massed planet orbiting at 〜3.4 AU (astronomical units). PICTURE sought to capture a direct, visible-light image of dust-scattered starlight in this system with the aid of a high-contrast nulling coronagraph. The design and laboratory testing of the PICTURE science payload is presented. Although the mission returned no science data, several important technological advances were made to enable future direct imaging missions. Most notably, PICTURE demonstrated 5.1 milliarcsecond pointing stability using a fast optical tracking system.

Pointer et sélectionner une cible avec un curseur est une interaction omniprésente dans l'utilisation des ordinateurs. La sélection peut néanmoins être difficile à réaliser si le contrôle du curseur n'est pas aisé, ou encore si la cible est petite ou distante. Aussi, faciliter la sélection de cibles est un thème essentiel et actif en Interaction Homme-Machine (IHM) et les techniques conçues sont nombreuses.Notre travail de recherche se focalise sur l'étude des techniques d'expansion de cibles. Celles-ci facilitent le pointage et la sélection en allouant à une cible une plus grande zone active, sans toutefois modifier la cible elle-même. L'algorithme d'expansion d'une technique détermine la zone active étendue de chaque cible, tandis que l'aide visuelle de la technique fournit à l'utilisateur les informations nécessaires pour exploiter l'expansion lors du pointage et sélection. Notre travail est dédié à l'aide visuelle des techniques d'expansion de cibles en abordant leur conception et leur impact sur les performances.Nous proposons dans un premier temps un espace de conception des aides visuelles. Cet espace est accompagné d'une notation matricielle de description des aides visuelles et permet une classification des techniques d'expansion existantes. Son pouvoir génératif s'illustre par la création de huit techniques d'expansion, que nous évaluons au travers de deux expériences en laboratoire. Les résultats de ces deux expériences nous permettent de formuler un ensemble de recommandations pour les concepteurs de techniques d'expansion.Nous avançons ensuite un modèle conceptuel de performance des techniques d'expansion. Ce modèle s'appuie sur la notion de pertinence de l'information contenue dans l'aide visuelle des techniques. Il considère une tâche de sélection sous l'angle cognitif en la décomposant en trois phases déterminées par les buts de l'utilisateur : la phase préliminaire au geste, la phase de transfert du curseur vers la cible et la phase de validation de la sélection. Nous confrontons ce modèle de performance avec des résultats expérimentaux de la littérature et d'une troisième expérience en laboratoire.Nos contributions sont appliquées à l'interaction chirurgien-ordinateur en contexte per-opératoire, c'est-à-dire en bloc opératoire durant une intervention chirurgicale. En particulier, l'entreprise partenaire de cette thèse CIFRE, Aesculap, intègre dans la prochaine version du produit OrthoPilot, un système informatique pour la chirurgie orthopédique, une des techniques d'expansion étudiées. Nous présentons également Medical TapTap, une nouvelle technique d'interaction gestuelle au pied conçue pour la validation de la sélection en contexte per-opératoire. / Pointing to/ Selecting targets is an elementary task universally present in graphical user interfaces (GUI). This task can be difficult to perform if the control of the cursor is not easy or if the target is far away or small. Thus facilitating target selection is a fundamental and active research topic in Human-Computer Interaction (HCI) and researchers have proposed numerous targeting assistance techniques.Our research focuses on targeting assistance techniques that allocate larger activation areas to targets. Such target expansion techniques rely on two basic elements: the expansion algorithm and the visual aid. The expansion algorithm distributes partly or wholly the free space among the targets. The visual aid presents the resulting target expansion to the users. Our work is dedicated to the visual aid that enables the users to take full advantage of the target expansion technique during the pointing/selection tasks.We first propose a three-axes design space for visual aid mechanisms. We further define a matrix-based notation for concisely describing a target expansion technique along the three design axes. We provide an analytical exploration of the design space by classifying existing target expansion techniques and by designing eight novel target expansion techniques, thus demonstrating the generative power of the design space. We also provide an experimental exploration of the design space by conducting two in-lab experiments. Based on the experimental results, we build a set of design recommendations.We then put forward a conceptual predictive model of performance. The model relies on a systematic analysis of the relevance of the visual aid provided by a target expansion technique based on the three goal-oriented phases of a selection task: the starting phase to initiate the movement towards the target, the transfer phase to bring the cursor into the goal target and the selection validation phase. To test the model we consider experimental results of the literature and of a third conducted in-lab experiment.Our contributions are applied to the field of Augmented Surgery and in particular interaction with a distant screen during a surgery in the operating theatre. As part of a Aesculap-CIFRE thesis, the next version of the product Aesculap’s OrthoPilot® Navigation System for orthopaedic surgery will include a target expansion technique for facilitating target selection by the surgeon in the operating theatre. We also provide a new foot gesture-based technique, namely Medical TapTap, for the validation of selection in the operating theatre.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / Orbiting satellites can be tracked by following preprogrammed ephemeris data in the ground station controller. This tracking method is advantageous, because of the reduced acquisition cost of non-autotracking receiver and antenna feed components. Further, widely separated frequency bands can readily be tracked, without the complexity of a frequency specific auto-track system. Two types of mobile tracking systems are described. They are composed of elevation-over-azimuth-over-tilt and of an X-Y axis pedestal configuration. The calibration methods for establishing time and geographical references are discussed, as well as the challenges of minimizing the effects of system and environment induced error contributors.

Previous natural observations have found a robust correlation between infants’ spontaneous gesture production and vocabulary development: the onset and frequency of infants’ pointing gestures are significantly correlated to their subsequent vocabulary size (Colonnesi, Stams, Koster, & Noom, 2010). The present study first examined the correlations between pointing and vocabulary size in an experimental setting, and then experimentally manipulated responses to pointing, to investigate the role of pointing in infants’ forming word-object associations. In the first experiment, we elicited 12- to 24-month old infants’ pointing gestures to 8 familiar and 8 novel objects. Their vocabulary was assessed by the MacArthur Communicative Development Inventory (MCDI): Words and Gestures. Results showed that 12-16 month old infants’ receptive vocabulary was positively correlated to infants’ spontaneous pointing. This correlation, however, was not significant in 19-24 month old infants. This experiment thus generalizes the previous naturalistic observation findings to an experimental setting, and shows a developmental change in the relation between pointing and receptive vocabulary. Together with prior studies, it suggests a possible positive social feedback loop of pointing and language skills in infants younger than 18 months old: the bigger vocabulary size infants have, the more likely they point, the more words they hear, and then the faster they develop their vocabulary. In the second experiment, we tested whether 16-month-old infants’ pointing gestures facilitate infants’ word learning in the moment. Infants were randomly assigned to one of three conditions: the experimenter labeled an unfamiliar object with a novel name 1) immediately after the infant pointed to it (the point contingent condition); 2) when the infant looked at it; or 3) at a schedule predetermined by a vocabulary-matched infant in the point contingent condition. After hearing the objects’ names, infants were presented with a word learning test. Results showed that infants successfully selected the correct referent above chance level only in the point contingent condition, and their performance was significantly better in the point contingent condition than the other two conditions. Therefore, only words that were provided contingently after pointing were learned. Taken together, these two studies further our understanding of the correlation between early gesture and vocabulary development and suggest that pointing plays a role in early word learning.

Thesis (M.A.)--University of Nevada, Reno, 2006. / "May 15, 2006." Includes bibliographical references (leaves 24-28). Online version available on the World Wide Web.

Deictic pointing—pointing at things during conversations—is natural and ubiquitous in human communication. Deictic pointing is important in the real world; it is also important in collaborative virtual environments (CVEs) because CVEs are 3D virtual environments that resemble the real world. CVEs connect people from different locations, allowing them to communicate and collaborate remotely. However, the interaction and communication capabilities of CVEs are not as good as those in the real world. In CVEs, people interact with each other using avatars (the visual representations of users). One problem of avatars is that they are not expressive enough when compare to what we can do in the real world. In particular, deictic pointing has many limitations and is not well supported. This dissertation focuses on improving the expressiveness of distant pointing—where referents are out of reach—in desktop CVEs. This is done by developing a framework that guides the design and development of pointing techniques; by identifying important aspects of distant pointing through observation of how people point at distant referents in the real world; by designing, implementing, and evaluating distant-pointing techniques; and by providing a set of guidelines for the design of distant pointing in desktop CVEs. The evaluations of distant-pointing techniques examine whether pointing without extra visual effects (natural pointing) has sufficient accuracy; whether people can control free arm movement (free pointing) along with other avatar actions; and whether free and natural pointing are useful and valuable in desktop CVEs. Overall, this research provides better support for deictic pointing in CVEs by improving the expressiveness of distant pointing. With better pointing support, gestural communication can be more effective and can ultimately enhance the primary function of CVEs—supporting distributed collaboration.

The harsh conditions of space, the stringent requirements for orbiting devices, and the increasing precision pointing requirements of many space applications demand an actuator that can provide necessary force while using less space and power than its predecessors. Ideally, this actuator would be able to isolate vibrations and never fail due to mechanical wear, while pointing with unprecedented accuracy. This actuator has many space applications from satellite optical communications and satellite appendage positioning to orbiting telescopes. This thesis presents the method of design of such an actuator a self-bearing motor. The actuator uses Lorentz forces to generate both torque and bearing forces. It has a slotless winding configuration with four sets of three-phase currents. A stand-alone software application, LFMD, was written to automatically optimize and configure such a motor according to a designers application requirements. The optimization is done on the bases of minimum powerloss, minimum motor outer diameter, minimum motor mass, and minimum length. Using that program, two sample space applications are analyzed and applicable motor configurations are presented.

Thesis (Ph. D.)--University of Chicago, Department of Psychology, December 1999. / Includes bibliographical references. Also available on the Internet.

One of the potential solutions to the radio frequency (RF) spectrum scarcity problem is optical wireless communications (OWC), which utilizes the unlicensed optical spectrum. Long-range outdoor OWC are usually referred to in the literature as free-space optical (FSO) communications. Unlike RF systems, FSO is immune to interference and multi-path fading. Also, the deployment of FSO systems is flexible and much faster than optical fibers. These attractive features make FSO applicable for broadband wireless transmission such as optical fiber backup, metropolitan area network, and last mile access. Although FSO communication is a promising technology, it is negatively affected by two physical phenomenon, namely, scintillation due to atmospheric turbulence and pointing errors. These two critical issues have prompted intensive research in the last decade. To quantify the effect of these two factors on FSO system performance, we need effective mathematical models. In this work, we propose and study a generalized pointing error model based on the Beckmann distribution. Then, we aim to generalize the FSO channel model to span all turbulence conditions from weak to strong while taking pointing errors into consideration. Since scintillation in FSO is analogous to the fading phenomena in RF, diversity has been proposed too to overcome the effect of irradiance fluctuations. Thus, several combining techniques of not necessarily independent dual-branch free-space optical links were investigated over both weak and strong turbulence channels in the presence of pointing errors. On another front, improving the performance, enhancing the capacity and reducing the delay of the communication link has been the motivation of any newly developed schemes, especially for backhauling. Recently, there has been a growing interest in practical systems to integrate RF and FSO technologies to solve the last mile bottleneck. As such, we also study in this thesis asymmetric an RF-FSO dual-hop relay transmission system with both fixed and variable gain relay.

This dissertation explores the emergence of the linguistic use of pointing as first- and non-first-person pronoun in Greek Sign Language. Despite the similarity in form between the pointing gesture and pronominal pointing signs, children acquiring sign language pass through the same stages and acquire personal pronouns at about the same age as children acquiring spoken language. According to Petitto (1984, 1987, 1994), the transition to pronominal pointing in American Sign Language is characterised by: (a) a period of discontinuity in which children avoid using pointing directed towards persons, and (b) the occurrence of reversal errors before the acquisition of first and second-person pronouns. The present study offers additional evidence on the acquisition of personal pronouns through the investigation of: (a) the manner and the age at which pronominal pointing signs are acquired by a child exposed to Greek Sign Language, (b) the use of other signs for reference to persons and self, and (c) the existence of reversal errors in the child’s early use of pointing. Data consist of video-recorded spontaneous interaction between a deaf boy and his family every fortnight from the age of 12 to 36 months. Thirty hours of the child’s communicative behaviour have been transcribed and all sequences that included pointing were analysed in terms of reference and function. This study confirms that language modality plays a restricted role in language acquisition. The time and the frequency of occurrence of pronominal pointing signs correspond to the general developmental pattern observed in the acquisition of ASL. However, there are also important differences: (a) common nouns and proper names are used for reference to others before the acquisition of pronominal pointing, but to a limited extent (b) the existence of only one erroneous pointing sign indicates that the deaf child, from the beginning, uses pronominal signs correctly, and (c) there is no evidence of discontinuity in the transition from the early communicative pointing gesture to pronominal pointing signs. / <p>För att köpa boken skicka en beställning till exp@ling.su.se/ To order the book send an e-mail to exp@ling.su.se</p>