TIM, ray-tracing program for forbidden optics

TIM (The Interactive METATOY) is a ray-tracing program specifically tailored towards our research in METATOYs, which are optical components that appear to be able to create wave-optically forbidden light-ray fields. For this reason, TIM possesses features not found in other ray-tracing programs. TIM can either be used interactively or by modifying the openly available source code; in both cases, it can easily be run as an applet embedded in a web page. Here we describe the basic structure of TIM's source code and how to extend it, and we give examples of how we have used TIM in our own research.Comment: 19 pages, 15 figure

Dr TIM: Ray-tracer TIM, with additional specialist scientific capabilities

We describe several extensions to TIM, a raytracing program for ray-optics research. These include relativistic raytracing; simulation of the external appearance of Eaton lenses, Luneburg lenses and generalized focusing gradient-index (GGRIN) lenses, which are types of perfect imaging devices; raytracing through interfaces between spaces with different optical metrics; and refraction with generalised confocal lenslet arrays, which are particularly versatile METATOYs.Comment: 12 pages, 16 figure

The Long Wavelength Array Software Library

The Long Wavelength Array Software Library (LSL) is a Python module that provides a collection of utilities to analyze and export data collected at the first station of the Long Wavelength Array, LWA1. Due to the nature of the data format and large-N ($\gtrsim$100 inputs) challenges faced by the LWA, currently available software packages are not suited to process the data. Using tools provided by LSL, observers can read in the raw LWA1 data, synthesize a filter bank, and apply incoherent de-dispersion to the data. The extensible nature of LSL also makes it an ideal tool for building data analysis pipelines and applying the methods to other low frequency arrays.Comment: accepted to the Journal of Astronomical Instrumentation; 24 pages, 4 figure

Gaze Estimation Technique for Directing Assistive Robotics

AbstractAssistive robotics may extend capabilities for individuals with reduced mobility or dexterity. However, effective use of robotic agents typically requires the user to issue control commands in the form of speech, gesture, or text. Thus, for unskilled or impaired users, the need for a paradigm of intuitive Human-Robot Interaction (HRI) is prevalent. It can be inferred that the most productive interactions are those in which the assistive agent is able to ascertain the intention of the user. Also, to perform a task, the agent must know the user's area of attention in three-dimensional space. Eye gaze tracking can be used as a method to determine a specific Volume of Interest (VOI). However, gaze tracking has heretofore been under-utilized as a means of interaction and control in 3D space. This research aims to determine a practical volume of interest in which an individual's eyes are focused by combining past methods in order to achieve greater effectiveness. The proposed method makes use of eye vergence as a useful depth discriminant to generate a tool for improved robot path planning. This research investigates the accuracy of the Vector Intersection (VI) model when applied to a usably large workspace volume. A neural network is also used in tandem with the VI model to create a combined model. The output of the combined model is a VOI that can be used as an aid in a number of applications including robot path planning, entertainment, ubiquitous computing, and others

Topological and electrostatic properties of diclofenac molecule as a non-steroidal anti-inflammatory drug: An experimental and theoretical study

International audienceDiclofenac is a Non-Steroidal Anti-Inflammatory Drug (NSAID), which highly inhibits the lipoxygenase pathways and reduces the formation of leukotriene lipids. In this work, we report on measurements and calculations of the electron density of Diclofenac, obtained from high resolution experimental X-ray diffraction data at 110K and theoretical calculations. The supramolecular structure is dominated by the formation of a dimer through COOH homo-synthon. The analysis of the molecular electron density (by means of quantum theory of atoms in molecules), the electrostatic potential, the crystal packing and intermolecular interactions (through Hirshfeld surface analysis) enables gaining more insight into the nature of the 2 molecule and its ability to interact with other molecules. Furthermore, the topological properties of the dimer interactions in both the crystal phase and human transthyretin protein environment were identified. The electrostatic potential map shows that the high electronegative regions appear around the carboxyl group of the diclofenac molecule in both the crystal and protein environment. This study is complemented by a molecular dynamics simulation of the interaction of diclofenac with transthyretin protein, which enables to test the hypothesis made with the charge density analysis

Direct Manipulation Of Virtual Objects

Interacting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user\u27s real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world. Complicating matters further, VEs presented by currently available visual displays may be inaccurate or distorted due to technological limitations. Fundamental physiological and psychological aspects of vision as they pertain to the task of object manipulation were thoroughly reviewed. Other sensory modalities--proprioception, haptics, and audition--and their cross-interactions with each other and with vision are briefly discussed. Visual display technologies, the primary component of any VE, were canvassed and compared. Current applications and research were gathered and categorized by different VE types and object interaction techniques. While object interaction research abounds in the literature, pockets of research gaps remain. Direct, dexterous, manual interaction with virtual objects in Mixed Reality (MR), where the real, seen hand accurately and effectively interacts with virtual objects, has not yet been fully quantified. An experimental test bed was designed to provide the highest accuracy attainable for salient visual cues in personal space. Optical alignment and user calibration were carefully performed. The test bed accommodated the full continuum of VE types and sensory modalities for comprehensive comparison studies. Experimental designs included two sets, each measuring depth perception and object interaction. The first set addressed the extreme end points of the Reality-Virtuality (R-V) continuum--Immersive Virtual Environment (IVE) and Reality Environment (RE). This validated, linked, and extended several previous research findings, using one common test bed and participant pool. The results provided a proven method and solid reference points for further research. The second set of experiments leveraged the first to explore the full R-V spectrum and included additional, relevant sensory modalities. It consisted of two full-factorial experiments providing for rich data and key insights into the effect of each type of environment and each modality on accuracy and timeliness of virtual object interaction. The empirical results clearly showed that mean depth perception error in personal space was less than four millimeters whether the stimuli presented were real, virtual, or mixed. Likewise, mean error for the simple task of pushing a button was less than four millimeters whether the button was real or virtual. Mean task completion time was less than one second. Key to the high accuracy and quick task performance time observed was the correct presentation of the visual cues, including occlusion, stereoscopy, accommodation, and convergence. With performance results already near optimal level with accurate visual cues presented, adding proprioception, audio, and haptic cues did not significantly improve performance. Recommendations for future research include enhancement of the visual display and further experiments with more complex tasks and additional control variables

Development of crystallographic surfaces for modelling interactions

This thesis addresses two separate problems - an investigation of the interaction of probe molecules with crystalline rutile and an investigation of the environment of group IA and IIA elements in organometallic compounds. Ab-initio Hartree-Fock calculations have been performed, aimed at investigating the interactions between the ionic surface of a crystal and an adsorbate molecule. Titanium dioxide, a material important for catalysis, electronic components and pigments, was chosen as the substrate, with carbon monoxide as the probe molecule. The calculations were carried out using the Crystal92 program, for the (110) surface of the Rutile polymorph of TiO(_2), employing a slab with a thickness of 5 atomic layers. The calculations investigated two orientations of the CO molecule with the molecular axis perpendicular to the surface. Results are reported showing contour diagrams for slices through the energy hypersurface parallel and perpendicular to the surface of the substrate. In order to facilitate the work described above, a program 'Builder2' was developed. This provides a convenient means for generating models of slabs of material from crystal structure data. Part of the development of Builder2 was to devise computer code to decompose standard Space Group symbols into the underlying symmetry matrices. The code for Builder2 is proprietary to Oxford Materials Ltd. and forms part of a commercial product. The environment of group IA and IIA elements in crystalline materials has not been the subject of any reported investigation. These elements, and organic ligands associated with them, play a significant role in biological systems. Around 16,000 atomic environments were extracted from the Cambridge Crystallographic Database to provide an up-to-date analysis of actual environments. The results are presented as histograms and tables, and suggestions are made for future extension of the analyses

Immersive design engineering

Design Engineering is an innovative field that usually combines a number of disciplines, such as material science, mechanics, electronics, and/or biochemistry, etc. New immersive technologies, such as Virtual Reality (VR) and Augmented Reality (AR), are currently in the process of being widely adapted in various engineering fields. It is a proven fact that the modeling of spatial structures is supported by immersive exploration. But the field of Design Engineering reaches beyond standard engineering tasks. With this review paper we want to achieve the following: define the term “Immersive Design Engineering”, discuss a number of recent immersive technologies in this context, and provide an inspiring overview of work that belongs to, or is related to the field of Immersive Design Engineering. Finally, the paper concludes with definitions of research questions as well as a number of suggestions for future developments

Neural dynamics of invariant object recognition: relative disparity, binocular fusion, and predictive eye movements

How does the visual cortex learn invariant object categories as an observer scans a depthful scene? Two neural processes that contribute to this ability are modeled in this thesis. The first model clarifies how an object is represented in depth. Cortical area V1 computes absolute disparity, which is the horizontal difference in retinal location of an image in the left and right foveas. Many cells in cortical area V2 compute relative disparity, which is the difference in absolute disparity of two visible features. Relative, but not absolute, disparity is unaffected by the distance of visual stimuli from an observer, and by vergence eye movements. A laminar cortical model of V2 that includes shunting lateral inhibition of disparity-sensitive layer 4 cells causes a peak shift in cell responses that transforms absolute disparity from V1 into relative disparity in V2. The second model simulates how the brain maintains stable percepts of a 3D scene during binocular movements. The visual cortex initiates the formation of a 3D boundary and surface representation by binocularly fusing corresponding features from the left and right retinotopic images. However, after each saccadic eye movement, every scenic feature projects to a different combination of retinal positions than before the saccade. Yet the 3D representation, resulting from the prior fusion, is stable through the post-saccadic re-fusion. One key to stability is predictive remapping: the system anticipates the new retinal positions of features entailed by eye movements by using gain fields that are updated by eye movement commands. The 3D ARTSCAN model developed here simulates how perceptual, attentional, and cognitive interactions across different brain regions within the What and Where visual processing streams interact to coordinate predictive remapping, stable 3D boundary and surface perception, spatial attention, and the learning of object categories that are invariant to changes in an object's retinal projections. Such invariant learning helps the system to avoid treating each new view of the same object as a distinct object to be learned. The thesis hereby shows how a process that enables invariant object category learning can be extended to also enable stable 3D scene perception

The Glitch Aesthetic

The miscommunication between sender and receiver during transcoding indexes specific historical moments similarly to analog film\u27s indexical trace. Iconography and glitch art begin to establish glitch\u27s deictic index. The glitch aesthetic exposes societal paranoia by illustrating dependence on the digital and fear of system failure. With the advent of video sharing sites like Youtube and popular cyberfilms, the glitch aesthetic has evolved into a pop culture artifact