Towards Immersive Virtual Reality Simulations of Bionic Vision

Bionic vision is a rapidly advancing field aimed at developing visual neuroprostheses ('bionic eyes') to restore useful vision to people who are blind. However, a major outstanding challenge is predicting what people 'see' when they use their devices. The limited field of view of current devices necessitates head movements to scan the scene, which is difficult to simulate on a computer screen. In addition, many computational models of bionic vision lack biological realism. To address these challenges, we propose to embed biologically realistic models of simulated prosthetic vision (SPV) in immersive virtual reality (VR) so that sighted subjects can act as 'virtual patients' in real-world tasks.Comment: 3 pages, 2 figures, to be presented at Augmented Human

Conscience and Attestation : The Methodological Role of the “Call of Conscience” (Gewissensruf) in Heidegger’s Being and Time

Travail réalisé en cotutelle (Université de Paris IV-La Sorbonne).Cette étude vise à exposer le rôle méthodologique que Martin Heidegger attribue à la conscience (Gewissen) dans Être et temps et à faire ressortir les implications de son interprétation de « l’appel de la conscience » comme le moyen de produire l’attestation (Bezeugung) de l’existence authentique en tant que possibilité du Dasein (ou être-dans-le-monde). Notre objectif initial est de montrer comment la notion heideggérienne de conscience a évolué avant la publication d’Être et temps en 1927 et d’identifier les sources qui ont contribué à l’interprétation existentiale de la conscience comme « l’appel du souci. » Notre analyse historique révèle notamment que Heidegger n’a jamais décrit la conscience comme un « appel » avant sa lecture du livre Das Gewissen (1925) par Hendrik G. Stoker, un jeune philosophe sud-africain qui a étudié à Cologne sous la direction de Max Scheler. Nous démontrons plus spécifiquement comment l’étude phénoménologique de Stoker—qui décrit la conscience comme « l’appel du devoir (Pflichtruf) » provenant de l’étincelle divine (synteresis) placée dans l’âme de chaque personne par Dieu—a influencé l’élaboration du concept de « l’appel existentiel » chez Heidegger. Mettant l’accent sur le rôle méthodologique de la conscience dans Être et temps, nous soulignons aussi l’importance des liens entre son concept de la conscience et la notion de « l’indication formelle » que Heidegger a mise au cœur de sa « méthode » dans ses cours sur la phénoménologie à Freiburg et Marbourg. Alors que de nombreux commentateurs voient dans « l’appel de la conscience » une notion solipsiste qui demeure impossible en tant qu’expérience, nous proposons un moyen de lever cette difficulté apparente en tentant de faire ressortir ce qui est « indiqué formellement » par la notion même de la conscience (Gewissen) dans Être et temps. Cette approche nous permet d’affirmer que le concept de conscience chez Heidegger renvoie à un phénomène de « témoignage » qui est radicalement différent de la notion traditionnelle de conscientia. Guidé par les principes mêmes de la phénoménologie heideggérienne, nous procédons à une analyse « destructrice » de l’histoire du mot allemand Gewissen qui nous révèle que la signification originelle de ce mot (établie dans le plus ancien livre préservé dans la langue allemande : le Codex Abrogans) était testimonium et non conscientia. À l’origine, Gewissen signifiait en effet « attestation »—ce qui est précisément le rôle assigné à la conscience par Heidegger dans Être et temps. Sur la base de cette découverte, nous proposons une manière de comprendre cette « attestation » comme une expérience possible : l’écoute du « témoignage silencieux » du martyr qui permet à Dasein de reconnaître sa propre possibilité d’authenticité.This study aims to exhibit the methodological role that Martin Heidegger assigns to conscience (Gewissen) in Being and Time and to reveal the implications of his interpretation of the “call of conscience” as the means of producing the attestation (Bezeugung) of authentic existence as a possibility of Being-in-the-world (or Dasein). We begin by seeking to understand how Heidegger’s notion of conscience evolved prior to the 1927 publication of Being and Time and to identify the sources which contributed to his interpretation of conscience as the “call of care.” Our historical analysis notably reveals that Heidegger never once describes conscience as a “call” before reading Das Gewissen (1925) by Hendrik G. Stoker, a young South African philosopher who studied under Max Scheler’s direction at the University of Cologne. We specifically examine how Stoker’s phenomenological study—which describes conscience as the “call-of-duty” issued to each human being by the divine “spark” (synteresis) placed in his or her soul by God—contributed to shaping Heidegger’s account of the “existential call.” Focusing on the methodological role of conscience in Being and Time, we analyze Heidegger’s major work in light of his early lectures on phenomenology at Freiburg and Marburg. This approach confirms the relation between conscience in Being and Time and the concept of “formal indication” that Heidegger placed at the heart of his evolving “method” of phenomenological investigation. While many commentators have argued that Heidegger’s “call of conscience” is solipsistic and impossible to experience, we propose a way of reconsidering this apparent impasse by examining what Being and Time itself “formally indicates” with regard to conscience. We show that Heidegger’s conscience points to a phenomenon of existential “testimony” which is radically different from the traditional notion of conscientia. Guided by Heidegger’s “formal indication” of conscience, we “destructively” review the history of the German word Gewissen and reveal its original meaning to be “testimonium” not “conscientia.” In recognizing that Gewissen originally meant “attestation,” we show how Heidegger’s existential phenomenon of conscience can be understood as Dasein’s experience of hearing the “silent testimony” of the martyr

A Systematic Review of Extended Reality (XR) for Understanding and Augmenting Vision Loss

Over the past decade, extended reality (XR) has emerged as an assistive technology not only to augment residual vision of people losing their sight but also to study the rudimentary vision restored to blind people by a visual neuroprosthesis. To make the best use of these emerging technologies, it is valuable and timely to understand the state of this research and identify any shortcomings that are present. Here we present a systematic literature review of 227 publications from 106 different venues assessing the potential of XR technology to further visual accessibility. In contrast to other reviews, we sample studies from multiple scientific disciplines, focus on augmentation of a person's residual vision, and require studies to feature a quantitative evaluation with appropriate end users. We summarize prominent findings from different XR research areas, show how the landscape has changed over the last decade, and identify scientific gaps in the literature. Specifically, we highlight the need for real-world validation, the broadening of end-user participation, and a more nuanced understanding of the suitability and usability of different XR-based accessibility aids. By broadening end-user participation to early stages of the design process and shifting the focus from behavioral performance to qualitative assessments of usability, future research has the potential to develop XR technologies that may not only allow for studying vision loss, but also enable novel visual accessibility aids with the potential to impact the lives of millions of people living with vision loss

A Wannier-function-based ab initio Hartree-Fock study of polyethylene

In the present letter, we report the extension of our Wannier-function-based ab initio Hartree-Fock approach---meant originally for three-dimensional crystalline insulators---to deal with quasi-one-dimensional periodic systems such as polymers. The system studied is all-transoid polyethylene, and results on optimized lattice parameters, cohesive energy and the band structure utilizing 6-31G** basis sets are presented. Our results are also shown to be in excellent agreement with those obtained with traditional Bloch-orbital-based approaches.Comment: 15 Pages, RevTex, inludes four figures, Chem. Phys. Letts., in press (1998

International Health Regulations—What Gets Measured Gets Done

Focus on goals and metrics for 4 core capacities illustrates 1 approach to implementing IHR

Van Hove Excitons and High-Tc_c Superconductivity: VIIIC Dynamic Jahn-Teller Effects vs Spin-Orbit Coupling in the LTO Phase of La2−x_{2-x}Srx_xCuO4_4

The possible role of the van Hove singularity (vHs) in stabilizing the low-temperature orthorhombic (LTO) phase transition in La$_{2-x}$\-Sr$_x$\-CuO$_ 4$ (LSCO) is discussed. It is found that the vHs can drive a structural distortion in two different ways, either due to spin-orbit coupling or to dynamic Jahn-Teller (JT) effects. This paper discusses the latter effect in some detail. It is shown that a model Hamiltonian introduced earlier to describe the coupled electron -- octahedral tilt motions (`cageons') has a series of phase transitions, from a high-temperature disordered JT phase (similar to the high-temperature tetragonal phase of LSCO) to an intermediate temperature dynamic JT phase, of average orthorhombic symmetry (the LTO phase) to a low temperature static JT phase (the low temperature tetragonal phase). For some parameter values, the static JT phase is absent.Comment: 28 pages plain TeX, 14 figures available upon request, NU-MARKIEWIC-93-0

Electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ

We study the electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ by means of density-functional band theory, Hubbard model calculations, and angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant quantitative and qualitative discrepancies to band theory. We demonstrate that the dispersive behavior as well as the temperature-dependence of the spectra can be consistently explained by the finite-energy physics of the one-dimensional Hubbard model at metallic doping. The model description can even be made quantitative, if one accounts for an enhanced hopping integral at the surface, most likely caused by a relaxation of the topmost molecular layer. Within this interpretation the ARPES data provide spectroscopic evidence for the existence of spin-charge separation on an energy scale of the conduction band width. The failure of the one-dimensional Hubbard model for the {\it low-energy} spectral behavior is attributed to interchain coupling and the additional effect of electron-phonon interaction.Comment: 18 pages, 9 figure

CpG Deamination Creates Transcription Factor–Binding Sites with High Efficiency

The formation of new transcription factor–binding sites (TFBSs) has a major impact on the evolution of gene regulatory networks. Clearly, single nucleotide mutations arising within genomic DNA can lead to the creation of TFBSs. Are molecular processes inducing single nucleotide mutations contributing equally to the creation of TFBSs? In the human genome, a spontaneous deamination of methylated cytosine in the context of CpG dinucleotides results in the creation of thymine (C → T), and this mutation has the highest rate among all base substitutions. CpG deamination has been ascribed a role in silencing of transposons and induction of variation in regional methylation. We have previously shown that CpG deamination created thousands of p53-binding sites within genomic sequences of Alu transposons. Interestingly, we have defined a ∼30 bp region in Alu sequence, which, depending on a pattern of CpG deamination, can be converted to functional p53-, PAX-6-, and Myc-binding sites. Here, we have studied single nucleotide mutational events leading to creation of TFBSs in promoters of human genes and in genomic regions bound by such key transcription factors as Oct4, NANOG, and c-Myc. We document that CpG deamination events can create TFBSs with much higher efficiency than other types of mutational events. Our findings add a new role to CpG methylation: We propose that deamination of methylated CpGs constitutes one of the evolutionary forces acting on mutational trajectories of TFBSs formation contributing to variability in gene regulation