scholarly journals Spatial organization of retinal information about the direction of image motion.

1995 ◽  
Vol 92 (9) ◽  
pp. 4002-4005 ◽  
Author(s):  
F. R. Amthor ◽  
C. W. Oyster
Keyword(s):  
Spatial Organization ◽  
Image Motion ◽  
Retinal Information

Smooth Pursuit of a Partially Occluded Object

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 150-150 ◽  
Author(s):  
L S Stone ◽  
J Lorenceau ◽  
B R Beutter
Keyword(s):  
Relative Phase ◽  
Object Motion ◽  
Image Motion ◽  
Visual Signal ◽  
Phase Lag ◽  
Motion Signal ◽  
Retinal Image Motion ◽  
The Mean ◽  
Partially Occluded ◽  
Retinal Information

There has long been qualitative evidence that humans can pursue an object defined only by the motion of its parts (eg Steinbach, 1976 Vision Research16 1371 – 1375). We explored this quantitatively using an occluded diamond stimulus (Lorenceau and Shiffrar, 1992 Vision Research32 263 – 275). Four subjects (one naive) tracked a line-figure diamond moving along an elliptical path (0.9 Hz) either clockwise (CW) or counterclockwise (CCW) behind either an X-shaped aperture (CROSS) or two vertical rectangular apertures (BARS), which obscured the corners. Although the stimulus consisted of only four line segments (108 cd m−2), moving within a visible aperture (0.2 cd m−2) behind a foreground (38 cd m−2), it is largely perceived as a coherently moving diamond. The intersaccadic portions of eye-position traces were fitted with sinusoids. All subjects tracked object motion with considerable temporal accuracy. The mean phase lag was 5°/6° (CROSS/BARS) and the mean relative phase between the horizontal and vertical components was +95°/+92° (CW) and −85°/−75° (CCW), which is close to perfect. Furthermore, a \chi2 analysis showed that 56% of BARS trials were consistent with tracking the correct elliptical shape ( p<0.05), although segment motion was purely vertical. These data disprove the main tenet of most models of pursuit: that it is a system that seeks to minimise retinal image motion through negative feedback. Rather, the main drive must be a visual signal which has already integrated spatiotemporal retinal information into an object-motion signal.

A Perplexing Puzzle Involving Perception of Straight Ahead

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 41-41
Author(s):  
J T Enright
Keyword(s):  
Internal Standard ◽  
Test Session ◽  
Image Motion ◽  
Visual Direction ◽  
Visual Environment ◽  
Visual Capture ◽  
Darkened Room ◽  
Standard Of Comparison ◽  
Retinal Information ◽  
Straight Ahead

Perception of visual direction was investigated by requiring subjects repeatedly to adjust a single small light, in an otherwise darkened room, to perceived ‘straight ahead’. This task presumably requires comparing concurrent extra-retinal information (either proprioception or an efference copy) with an internally stored ‘standard’ of comparison. Moment-to-moment precision in that performance is remarkably good, with median threshold (standard deviation) of 47 arc min. Nevertheless, the responses often involved a monotonic shift of direction over a few minutes during a test session in this reduced visual environment. These trends led to final settings that were immediately recognised as grossly erroneous when the room was relit, implying that the presumptive internal standard of comparison, while unstable, can be rapidly updated in a full visual environment. There are clear similarities between this phenomenon and the sudden ‘visual capture’ that occurs in a re-illuminated room, following distortions of visual direction that arose in a similarly reduced setting for subjects whose extraocular muscles were partially paralysed (Matin et al, 1982 Science216 198 – 201). In both cases, the visual stimuli that underlie rapid recalibration are unknown. Among the several possibilities that can be imagined, the strongest candidate hypothesis for this calibration of the straight-ahead direction is that, during fixation in a lit room, one utilises the directional distribution of image motion that arises because of microscale drift of the eye, as it moves toward its equilibrium orientation, much as a moving observer can use optic flow to evaluate ‘heading’ (the dynamic analogue of ‘straight ahead’).

Computational Micrograph Registration with Sieve Processes

1996 ◽  
Vol 54 ◽  
pp. 440-441
Author(s):  
P.J. Phillips ◽  
J. Huang ◽  
S. M. Dunn
Keyword(s):  
Planar Graph ◽  
Efficient Algorithm ◽  
Spatial Organization ◽  
Spatial Arrangement ◽  
Stereo Image ◽  
Image Model ◽  
Geometric Invariants ◽  
Point Set

In this paper we present an efficient algorithm for automatically finding the correspondence between pairs of stereo micrographs, the key step in forming a stereo image. The computation burden in this problem is solving for the optimal mapping and transformation between the two micrographs. In this paper, we present a sieve algorithm for efficiently estimating the transformation and correspondence.In a sieve algorithm, a sequence of stages gradually reduce the number of transformations and correspondences that need to be examined, i.e., the analogy of sieving through the set of mappings with gradually finer meshes until the answer is found. The set of sieves is derived from an image model, here a planar graph that encodes the spatial organization of the features. In the sieve algorithm, the graph represents the spatial arrangement of objects in the image. The algorithm for finding the correspondence restricts its attention to the graph, with the correspondence being found by a combination of graph matchings, point set matching and geometric invariants.

Caveolin-1, galectin-3 and lipid raft domains in cancer cell signalling

2015 ◽  
Vol 57 ◽  
pp. 189-201 ◽  
Author(s):  
Jay Shankar ◽  
Cecile Boscher ◽  
Ivan R. Nabi
Keyword(s):  
Plasma Membrane ◽  
Lipid Rafts ◽  
Cancer Cell ◽  
Cellular Response ◽  
Spatial Organization ◽  
Essential Feature ◽  
Cell Signalling ◽  
Coated Pits ◽  
Signalling Molecules ◽  
Raft Domains

Spatial organization of the plasma membrane is an essential feature of the cellular response to external stimuli. Receptor organization at the cell surface mediates transmission of extracellular stimuli to intracellular signalling molecules and effectors that impact various cellular processes including cell differentiation, metabolism, growth, migration and apoptosis. Membrane domains include morphologically distinct plasma membrane invaginations such as clathrin-coated pits and caveolae, but also less well-defined domains such as lipid rafts and the galectin lattice. In the present chapter, we will discuss interaction between caveolae, lipid rafts and the galectin lattice in the control of cancer cell signalling.

The Social Construction of a Perfect Market: The Strawberry Auction at Fontaines-en-Sologne

2010 ◽  
pp. 73-89
Author(s):  
M.-F. Garcia
Keyword(s):  
Economic Theory ◽  
Social Construction ◽  
Empirical Study ◽  
Spatial Organization ◽  
Frame Of Reference ◽  
Social Conditions ◽  
Invisible Hand ◽  
The Social ◽  
Per Se

The article examines social conditions and mechanisms of the emergence in 1982 of a «Dutch» strawberry auction in Fontaines-en-Sologne, France. Empirical study of this case shows that perfect market does not arise per se due to an «invisible hand». It is a social construction, which could only be put into effect by a hard struggle between stakeholders and large investments of different forms of capital. Ordinary practices of the market dont differ from the predictions of economic theory, which is explained by the fact that economic theory served as a frame of reference for the designers of the auction. Technological and spatial organization as well as principal rules of trade was elaborated in line with economic views of perfect market resulting in the correspondence between theory and reality.

Parameters Of Technological Processes Reengineering

2020 ◽  
pp. 28-33
Keyword(s):  
Spatial Organization ◽  
Parametric Model ◽  
Practical Significance ◽  
Machine Time ◽  
Time Machine ◽  
Technological Processes ◽  
Technical Capability ◽  
Materials Used ◽  
The Cost ◽  
Qualitative Characteristics

The article is devoted to reengineering of technological processes - a method of their qualitative transformation on an innovative basis, which in turn assumes the availability of tools that make it possible to establish the economic efficiency and technical capability of such transformations of construction production, to identify the effect of their implementation. In this regard, the problem of forming a parametric model of reengineering of construction technological processes, which involves four enlarged groups of indicators that reflect the quantitative and qualitative characteristics of the processes: materials used, working time, machine time, spatial organization, is considered. It is established that parameters can have either an absolute (physical, cost) or relative (point, percentage) expression and also make their own decomposition. The practical significance of the provisions given in the article is determined by the development of methods of technical rationing, which leads to a reduction in the cost and duration of construction.

ЛАНДШАФТНАЯ ОРГАНИЗАЦИЯ БЕРЕГОВОЙ ГЕОСТРУКТУРЫ ОСТРОВА ШКОТА (ЗАЛИВ ПЕТРА ВЕЛИКОГО)

2019 ◽  
Author(s):  
K.S. Ganzei ◽  
V.V. Zharikov ◽  
N.F. Pshenichnikova ◽  
A.M. Lebedev ◽  
A.G. Kiselyova ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Peter The Great Bay ◽  
Spatial Arrangement ◽  
Water Area ◽  
Marine Spatial Planning ◽  
Landscape Approach ◽  
Important Condition ◽  
Statistical Comparison ◽  
Peter The Great ◽  
Comprehensive Study

Важнейшим условием достижения устойчивого развития прибрежноморского природопользования в заливе Петра Великого системы является морское пространственное планирование. Основой для этого является информация о природных комплексах территории и акватории, полученная на основе ландшафтного подхода. Ключевым районом для изучения пространственной организации ландшафтов прибрежных геоструктур стала территория острова Шкота и его подводных склонов. Для наземных ландшафтов было описано 49 наблюдательных пунктов, 4 профиля были заложены для подводных ландшафтов описано 64 наблюдательных пункта, проложено 18 профилей. Выделено 22 вида ландшафтов, из них 16 наземных, 6 подводных. Берега острова сформированы преобладанием абразивноденудационного и абразивного типов. В результате всестороннего изучения показаны особенности пространственной организации воздушных и водных природных комплексов. Особенностью исследуемой территории является экспозиция дифференциации ландшафтов между юговосточной и северозападной частями острова, обусловленная муссонной природой климата. Результаты полевых и картографических работ послужили основой для выбора зон интенсивного, умеренного и ослабленного взаимодействия наземных и подводных ландшафтов. Пространственное расположение зон взаимодействия четко иллюстрируется значительными различиями экспозиции. Результаты статистического сравнения ландшафтов суши и мелководья, окружающего остров, на основе картометрических характеристик указывают на неоднородность геоструктуры острова, обусловленную, прежде всего, сочетанием ландшафтообразующих факторов. The most important condition for achieving sustainable development of coastalmarine environmental management in Peter the Great Bay is marine spatial planning. The basis for this is information about the natural complexes of the territory and water area, obtained based on the landscape approach. The main area for studying the spatial organization of landscapes of coastal geostructures was the territory of the island of Shkota and its underwater slopes. For terrestrial landscapes, 49 observation points were described, 4 profiles were laid 64 observation points were described for underwater landscapes, 18 profiles were laid. 22 species of landscapes have been identified, of which 16 are terrestrial, 6 are underwater. The shores of the island are formed by the predominance of abrasivedenudation and abrasive types. Because of a comprehensive study, features of the spatial organization of air and aquatic natural complexes are shown. A special feature of the study area is the exposure of the differentiation of landscapes between the southeastern and northwestern parts of the island, due to the monsoon nature of the climate. The results of field and cartographic works served as the basis for selecting areas of intense, moderate and weakened interaction of land and underwater landscapes. The spatial arrangement of the interaction zones is clearly illustrated by significant differences in exposure. The results of a statistical comparison of the land and shallow water landscapes surrounding the island, based on the cartometric characteristics, indicate the heterogeneity of the islands geostructure, primarily due to the combination of landscapeforming factors.

Sign in / Sign up

Export Citation Format

Share Document