ERG Components of Negative Polarity from the Inner Retina and the Optic Nerve Response

ERG components of negative polarity in the light-adapted and in the dark-adapted inner retina are reviewed from a clinical perspective and include consideration of experimental research. Field potentials are inherently complex including summating contributions from specialized neurons as well as from glial elements. This property applies to the PERG, PhNR and to the STR. Experimental research can contribute to identifying the sites/cells of origins i.e. by determining depth profiles and by pharmacological manipulation. Intraretinal microelectrode-studies and pharmacological dissection of light-evoked responses have elucidated the origin of field potentials from the retinal pigment epithelium to the retinal ganglion cells. Thresholds for dark-adapted response components have been compared. Attenuation of the STR by anesthesia was found in cats in vivo when compared to threshold intensities used in isolated eye preparations in vitro, suggestive of depression of inner retinal activity by anesthetics. Evidence has been presented for antidromically elicited retinal responses of negative polarity that resemble the STR and summate with the light-evoked retinal response. This observation supports the notion that negative field potentials and components as recorded in the vitreous and at the cornea receive contributions from retinal ganglion cells. The weight of this contribution appears to vary among species, at least concerning the STR. The ocular negative reponses from the inner retina are compared to cortical excitatory mechanisms generating negativity in the baseline of the EE

Modeling Induced Master Motion in Force-Reflecting Teleoperation

Providing the user with high-fidelity force feedback has persistently challenged the field of telerobotics. Interaction forces measured at the remote site and displayed to the user cause unintended master device motion. This movement is interpreted as a command for the slave robot and can drive the closed-loop system unstable. This paper builds on a recently proposed approach for achieving stable, high-gain force reflection via cancellation of the master mechanism’s induced motion. Such a strategy hinges on obtaining a good model of the master’s response to force feedback. Herein, we present a thorough modeling approach based on successive isolation of system components, demonstrated on a one-degree-of-freedom testbed. A sixth-order mechanical model, including viscous and Coulomb friction as well as a new method for modeling hysteretic stiffness, describes the testbed’s high-frequency resonant modes. This modeling method’s ability to predict induced master motion should lead to significant improvements in force-reflecting teleoperation via the cancellation approac

Improving Telerobotic Touch Via High-Frequency Acceleration Matching

Humans rely on information-laden high-frequency accelerations in addition to quasi-static forces when interacting with objects via a handheld tool. Telerobotic systems have traditionally struggled to portray such contact transients due to closed-loop bandwidth and stability limitations, leaving remote objects feeling soft and undefined. This work seeks to maximize the user’s feel for the environment through the approach of acceleration matching; high-frequency fingertip accelerations are combined with standard low-frequency position feedback without requiring a secondary actuator on the master device. In this method, the natural dynamics of the master are identified offline using frequency-domain techniques, estimating the relationship between commanded motor current and handle acceleration while a user holds the device. During subsequent telerobotic interactions, a high-bandwidth sensor measures accelerations at the slave’s end effector, and the real-time controller re-creates these important signals at the master handle by inverting the identified model. The details of this approach are explored herein, and its ability to render hard and rough surfaces is demonstrated on a standard master-slave system. Combining high-frequency acceleration matching with position-error-based feedback of quasi-static forces creates a hybrid signal that closely corresponds to human sensing capabilities, instilling telerobotics with a more realistic sense of remote touch

Event-Based Haptics and Acceleration Matching: Portraying and Assessing the Realism of Contact

Contact in a typical haptic environment resembles the experience of tapping on soft foam, rather than on a hard object. Event-based, high-frequency transient forces must be superimposed with traditional proportional feedback to provide realistic haptic cues at impact. We have developed a new method for matching the accelerations experienced during real contact, inverting a dynamic model of the device to compute appropriate force feedback transients. We evaluated this haptic rendering paradigm by conducting a study in which users blindly rated the realism of tapping on a variety of virtually rendered surfaces as well as on three real objects. Event-based feedback significantly increased the realism of the virtual surfaces, and the acceleration matching strategy was rated similarly to a sample of real wood on a foam substrate. This work provides a new avenue for achieving realism of contact in haptic interactions

DRAFT: EXPERIMENTS IN LOCAL FORCE FEEDBACK FOR HIGH-INERTIA, HIGH-FRICTION TELEROBOTIC SYSTEMS

ABSTRACT Many telerobotic systems include a slave robot with much larger inertial and frictional properties tha

Cross-sectional Study of Visual Acuity and Electroretinogram in Two Types of Dominant Drusen

PURPOSE. To compare the changes with increasing age of ERG parameters in relation to clinical data in two distinct phenotypes of genetically determined, dominantly inherited macular drusen: malattia leventinese (ML) and Zermatt macular dystrophy (ZMD). METHODS. Ganzfeld rod-and cone-electroretinograms (ERGs) from 15 patients affected with ML and 14 patients with ZMD and clinical data were analyzed retrospectively. The patients' ages ranged from 20 to 77 years in the ML group and from 9 to 74 years in the ZMD group. RESULTS. Both inherited macular degenerations caused a marked decrease in visual acuity, the latest after age 65. Most patients with ML retained good visual function (0.8 -1.0) until the fifth decade, followed by a rapid decrease in the fifth or sixth decade. ZMD is characterized by a relatively continuous decrease in visual acuity with increasing age. Morphologically, in the juvenile stages in both entities, drusen were observed at the posterior pole. Rod-driven and cone-driven ERG b-wave amplitudes decreased nearly linearly in ML and ZMD in accord with the normal loss of amplitude with increasing age. Implicit times of cone b-waves for ML increased markedly with age, whereas in ZMD the values were always prolonged beyond the normal range with a slight increase with age. CONCLUSIONS. In terms of visual acuity, the progression of both dominantly inherited macular dystrophies is quite different. This is not reflected in the amplitudes of the b-waves in the Ganzfeld ERGs, which decrease normally for both entities. Implicit times of the cone-b waves were more markedly prolonged in ML compared with ZMD. In-depth longitudinal documentation of the natural course of those dominantly inherited macular diseases should facilitate patient counseling. (Invest Ophthalmol Vis Sci. 2003;44:493-496) DOI:10.1167/iovs.01-0787 M acular degeneration is a major cause of legal blindness, not only for the elderly. Genetic predisposition for various subtypes of this disease has been postulated, often accompanied by other factors, such as oxidative stress, ultraviolet radiation, and accumulated light exposure. In this article, the natural course of two autosomal dominantly inherited macular drusen phenotypes is assessed. Both have been named after the geographical Swiss region, where the diseases are endemic: malattia leventinese (ML), identical with dominant drusen or Doyne honeycomb retinal dystrophy, and Zermatt macular dystrophy (ZMD). For ML, a single missense mutation at the residue 345 (R345W) of the EFEMP1 gene, coding for the epidermal growth factor (EGF)-containing fibrillin-like extracellular matrix protein-1 was identified by Stone et al. 1 in 1999 as the disease-causing mutation. For ZMD, Piguet et al. 2 determined a single mutation at codon 172 (R172W) of the RDS/ peripherin gene to be responsible for the development of the disease. Previously, R172W has been described as causing macular degeneration in a Japanese family. 3 Clinically, both genetic defects show complete penetrance. The hallmark of both degenerations is the presence of macular drusen already in the second decade of life, and patients in the advanced stages of disease have a significant decrease in visual acuity. 2,4 -9 In Ganzfeld ERG recordings, decrease in b-wave amplitudes have also been described in both diseases. 11 PATIENTS AND METHODS We retrospectively examined and compared data from 15 patients with ML and 14 patients affected by ZMD. All patients gave informed consent for the clinical and genetic examinations, and the study was conducted in accordance with the tenets of the World Medical Association's Declaration of Helsinki. In all patients, the respective genetic mutation was tested and confirmed (Laboratory of Molecular Genetics, University Hospital, Lausanne, Switzerland). 1,2 The patients' ages at time of examination ranged from 20 to 74 years in the ML group and from 9 to 77 years in the ZMD group. No systemic diseases affecting the eye were present in any patient. All patients' data are summarized in Particularly, we studied cross-sectionally the changes with age in ML and ZMD of visual acuity; extent of macular dystrophy signs, such as drusen or alterations in pigment epithelium; and Ganzfeld ERGs. The Ganzfeld ERGs were recorded according to the methods referred to in previous publications, 12-14 using Henke low-vacuum contact lens electrodes throughout. These methods were largely in accordance with the International Society for Clinical Electrophysiology of Vision (ISCEV) standards. From th

Um acervo, uma coleção e três problemas: a Coleção Jacques Pilon da Biblioteca da FAUUSP

Este artigo examina a constituição do Acervo de Projetos de arquitetura da Biblioteca da Faculdade de Arquitetura e Urbanismo da Universidade de São Paulo (FAUUSP), o tratamento da Coleção Jacques Pilon e os rendimentos do projeto de arquitetura como fonte documental a partir de três questões interligadas: a constituição do campo arquitetônico no Brasil; a história de São Paulo e sua arquitetura; e a contribuição dos arquitetos estrangeiros para a construção da cidade entre 1930 e 1960. A partir da abordagem de novas e velhas fontes de pesquisa, procura-se articular a história da arquitetura com outros campos do conhecimento nem sempre a ela relacionados, mas que juntos podem contribuir para uma leitura mais complexa da produção arquitetônica e para os esforços de revisão da historiografia da arquitetura moderna no Brasil.This article examines the establishment of the Archive of Projects of the Library of the Faculty of Architecture and Urbanism of the University of Sao Paulo (FAUUSP), the treatment of the Collection Jacques Pilon and the architectural design as a documentary source from three interconnected issues: the constitution of the architectural field in Brazil; the history of São Paulo and its architecture and the contribution of foreign architects to build the city between the years 1930 and 1960. From the approach of new and old sources of research, this article seeks to articulate the History of Architecture with other fields of knowledge not always related to it, but that together it can contribute to a more complex reading of architectural production and to efforts of reviewing the historiography of modern architecture in Brazil

The CMS Phase-1 pixel detector upgrade

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.Peer reviewe