scholarly journals Parietal Reach Region Encodes Reach Depth Using Retinal Disparity and Vergence Angle Signals

2009 ◽  
Vol 102 (2) ◽  
pp. 805-816 ◽  
Author(s):  
Rajan Bhattacharyya ◽  
Sam Musallam ◽  
Richard A. Andersen
Keyword(s):  
Reference Frame ◽  
Rhesus Macaques ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Motor Command ◽  
Three Dimensions ◽  
Relative Depth ◽  
Egocentric Distance ◽  
Population Activity ◽  
The Absolute

Performing a visually guided reach requires the ability to perceive the egocentric distance of a target in three-dimensional space. Previous studies have shown that the parietal reach region (PRR) encodes the two-dimensional location of frontoparallel targets in an eye-centered reference frame. To investigate how a reach target is represented in three dimensions, we recorded the spiking activity of PRR neurons from two rhesus macaques trained to fixate and perform memory reaches to targets at different depths. Reach and fixation targets were configured to explore whether neural activity directly reflects egocentric distance as the amplitude of the required motor command, which is the absolute depth of the target, or rather the relative depth of the target with reference to fixation depth. We show that planning activity in PRR represents the depth of the reach target as a function of disparity and fixation depth, the spatial parameters important for encoding the depth of a reach goal in an eye centered reference frame. The strength of modulation by disparity is maintained across fixation depth. Fixation depth gain modulates disparity tuning while preserving the location of peak tuning features in PRR neurons. The results show that individual PRR neurons code depth with respect to the fixation point, that is, in eye centered coordinates. However, because the activity is gain modulated by vergence angle, the absolute depth can be decoded from the population activity.

Extension of the Spatial PDI Model to Three Dimensions

1997 ◽  
Vol 84 (1) ◽  
pp. 176-178
Author(s):  
Frank O'Brien
Keyword(s):  
Population Density ◽  
Dimensional Space ◽  
Finite Lattice ◽  
Three Dimensional ◽  
Upper Bounds ◽  
Three Dimensions ◽  
Lower And Upper Bounds ◽  
Density Index ◽  
Three Dimensional Space

The author's population density index ( PDI) model is extended to three-dimensional distributions. A derived formula is presented that allows for the calculation of the lower and upper bounds of density in three-dimensional space for any finite lattice.

The Brain Stem Saccadic Burst Generator Encodes Gaze in Three-Dimensional Space

2008 ◽  
Vol 99 (5) ◽  
pp. 2602-2616 ◽  
Author(s):  
Marion R. Van Horn ◽  
Pierre A. Sylvestre ◽  
Kathleen E. Cullen
Keyword(s):  
Eye Movements ◽  
Brain Stem ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Saccadic Eye Movements ◽  
Three Dimensions ◽  
Related Information ◽  
Computer Based ◽  
Different Depths ◽  
The Brain

When we look between objects located at different depths the horizontal movement of each eye is different from that of the other, yet temporally synchronized. Traditionally, a vergence-specific neuronal subsystem, independent from other oculomotor subsystems, has been thought to generate all eye movements in depth. However, recent studies have challenged this view by unmasking interactions between vergence and saccadic eye movements during disconjugate saccades. Here, we combined experimental and modeling approaches to address whether the premotor command to generate disconjugate saccades originates exclusively in “vergence centers.” We found that the brain stem burst generator, which is commonly assumed to drive only the conjugate component of eye movements, carries substantial vergence-related information during disconjugate saccades. Notably, facilitated vergence velocities during disconjugate saccades were synchronized with the burst onset of excitatory and inhibitory brain stem saccadic burst neurons (SBNs). Furthermore, the time-varying discharge properties of the majority of SBNs (>70%) preferentially encoded the dynamics of an individual eye during disconjugate saccades. When these experimental results were implemented into a computer-based simulation, to further evaluate the contribution of the saccadic burst generator in generating disconjugate saccades, we found that it carries all the vergence drive that is necessary to shape the activity of the abducens motoneurons to which it projects. Taken together, our results provide evidence that the premotor commands from the brain stem saccadic circuitry, to the target motoneurons, are sufficient to ensure the accurate control shifts of gaze in three dimensions.

Estimating Three-Dimensional Space from Multiple Two-Dimensional Views

1993 ◽  
Vol 2 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Kristinn R. Thorisson
Keyword(s):  
Visual Search ◽  
Eye Movement ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Simple Algorithm ◽  
Three Dimensions ◽  
Limiting Factor ◽  
Single Subject ◽  
Search Performance ◽  
Two Dimensional

The most common visual feedback technique in teleoperation is in the form of monoscopic video displays. As robotic autonomy increases and the human operator takes on the role of a supervisor, three-dimensional information is effectively presented by multiple, televised, two-dimensional (2-D) projections showing the same scene from different angles. To analyze how people go about using such segmented information for estimations about three-dimensional (3-D) space, 18 subjects were asked to determine the position of a stationary pointer in space; eye movements and reaction times (RTs) were recorded during a period when either two or three 2-D views were presented simultaneously, each showing the same scene from a different angle. The results revealed that subjects estimated 3-D space by using a simple algorithm of feature search. Eye movement analysis supported the conclusion that people can efficiently use multiple 2-D projections to make estimations about 3-D space without reconstructing the scene mentally in three dimensions. The major limiting factor on RT in such situations is the subjects' visual search performance, giving in this experiment a mean of 2270 msec (SD = 468; N = 18). This conclusion was supported by predictions of the Model Human Processor (Card, Moran, & Newell, 1983), which predicted a mean RT of 1820 msec given the general eye movement patterns observed. Single-subject analysis of the experimental data suggested further that in some cases people may base their judgments on a more elaborate 3-D mental model reconstructed from the available 2-D views. In such situations, RTs and visual search patterns closely resemble those found in the mental rotation paradigm (Just & Carpenter, 1976), giving RTs in the range of 5-10 sec.

scholarly journals On a set of quartic surfaces in space of four dimensions; and a certain involutory transformation

1926 ◽  
Vol 110 (756) ◽  
pp. 700-708
Keyword(s):  
Present Note ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Quartic Surface ◽  
Four Dimensions ◽  
Cubic Surfaces ◽  
Mutual Relations ◽  
Quartic Surfaces ◽  
Three Dimensional Space

There exists in space of four dimensions an interesting figure of 15 lines and 15 points, first considered by Stéphanos (‘Compt. Rendus,’ vol. 93, 1881), though suggested very clearly by Cremona’s discussion of cubic surfaces in three-dimensional space. In connection with the figure of 15 lines there arises a quartic surface, the intersection of two quadrics, which is of importance as giving rise by projection to the Cyclides, as Segre has shown in detail (‘Math. Ann.,’ vol. 24, 1884). The symmetry of the figure suggests, howrever, the consideration of 15 such quartic surfaces; and it is natural to inquire as to the mutual relations of these surfaces, in particular as to their intersections. In general, two surfaces in space of four dimensions meet in a finite number of points. It appears that in this case any two of these 15 surfaces have a curve in common; it is the purpose of the present note to determine the complete intersection of any two of these 15 surfaces. Similar results may be obtained for a system of cubic surfaces in three dimensions, corresponding to those here given for this system of quartic surfaces in four dimensions, since the surfaces have one point in common, which may be taken as the centre of a projection.

Visual asymmetries for relative depth judgments in a three-dimensional space

2015 ◽  
Vol 99 ◽  
pp. 128-134 ◽  
Author(s):  
Ancrêt Szpak ◽  
Tobias Loetscher ◽  
John Bastian ◽  
Nicole A. Thomas ◽  
Michael E.R. Nicholls
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Relative Depth ◽  
Three Dimensional Space

Symmetry-adapted digital modeling II. The double-helix B-DNA

2016 ◽  
Vol 72 (3) ◽  
pp. 312-323 ◽  
Author(s):  
A. Janner
Keyword(s):  
Dimensional Space ◽  
Double Helix ◽  
Three Dimensional ◽  
Reduction Factor ◽  
Lattice Points ◽  
Three Dimensions ◽  
Coarse Grained ◽  
Digital Modeling ◽  
Dna Strands ◽  
Dna Double Helix

The positions of phosphorus in B-DNA have the remarkable property of occurring (in axial projection) at well defined points in the three-dimensional space of a projected five-dimensional decagonal lattice, subdividing according to the golden mean ratio τ:1:τ [with τ = (1+\sqrt {5})/2] the edges of an enclosing decagon. The corresponding planar integral indicesn1,n2,n3,n4(which are lattice point coordinates) are extended to include the axial indexn5as well, defined for each P position of the double helix with respect to the single decagonal lattice ΛP(aP,cP) withaP= 2.222 Å andcP= 0.676 Å. A finer decagonal lattice Λ(a,c), witha=aP/6 andc=cP, together with a selection of lattice points for each nucleotide with a given indexed P position (so as to define a discrete set in three dimensions) permits the indexing of the atomic positions of the B-DNA d(AGTCAGTCAG) derived by M. J. P. van Dongen. This is done for both DNA strands and the single lattice Λ. Considered first is the sugar–phosphate subsystem, and then each nucleobase guanine, adenine, cytosine and thymine. One gets in this way a digital modeling of d(AGTCAGTCAG) in a one-to-one correspondence between atomic and indexed positions and a maximal deviation of about 0.6 Å (for the value of the lattice parameters given above). It is shown how to get a digital modeling of the B-DNA double helix for any given code. Finally, a short discussion indicates how this procedure can be extended to derive coarse-grained B-DNA models. An example is given with a reduction factor of about 2 in the number of atomic positions. A few remarks about the wider interest of this investigation and possible future developments conclude the paper.

scholarly journals Improving Problem-Solving Skills with the Help of Plane-Space Analogies

2013 ◽  
Vol 3 (4) ◽  
pp. 79-98
Author(s):  
László Budai
Keyword(s):  
High School Students ◽  
Problem Solving ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Spatial Thinking ◽  
Great Promise ◽  
School Students ◽  
Problem Solving Skills ◽  
Plane Space

We live our lives in three-dimensional space and encounter geometrical problems (equipment instructions, maps, etc.) every day. Yet there are not sufficient opportunities for high school students to learn geometry. New teaching methods can help remedy this. Specifically our experience indicates that there is great promise for use of geometry programs, GeoGebra and DGS, combined with plane space analogies for the development of spatial thinking and problem-solving skills in the three dimensions of solid geometry.

scholarly journals The Life Mission Theory III. Theory of Talent

2003 ◽  
Vol 3 ◽  
pp. 1286-1293 ◽  
Author(s):  
Soren Ventegodt ◽  
Niels Jorgen Andersen ◽  
Joav Merrick
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Three Dimensions ◽  
Natural State ◽  
Human Form ◽  
The World ◽  
Sex And Sexuality ◽  
And Gender ◽  
Third Dimension

When we acknowledge our purpose as the essence of our self, when we take all our power into use in an effortless way, and when we fully accept our own nature — including sex and sexuality, our purpose of life takes the form of a unique talent. Using this talent gives the experience of happiness. A person in his natural state of being uses his core talent in a conscious, joyful, and effortless way, contributing to the world the best he or she has to offer. Full expression of self happens when a person, in full acceptance of body and life, with whole-hearted intension, uses all his personal powers to realize his core talent and all associated talents, to contribute to his beloved and to the world. Thus, self-actualisation is a result of a person fully expressing and realizing his core talent.The theory of talent states that a core talent can be expressed optimally when a human being takes possession of a three-dimensional space with the axis of purpose, power and gender, as we have a threefold need: 1-Acknowledging our core talent (our purpose of life) and intending it 2-Understanding our potential powers and manifesting them 3-Accepting our human form including our sex and expressing itThe first dimension is spiritual, the next dimension is mental, emotional and physical, and the third dimension is bodily and sexual. We manifest our talents in a giving movement from the bottom of our soul trough our biological nature onto the subject and object of the outer world. These three dimensions can be drawn as three axes, one saggital axis called purpose or love or me-you, one vertical axis called power or consciousness (light) or heaven-earth, and one horizontal axis called gender or joy or male-female. The three core dimensions of human existence are considered of equal importance for expression of our life purpose, life mission, or core talent. Each of the dimensions is connected to special needs. When these needs are not fulfilled, we suffer and if this suffering becomes unbearable we deny the dimension or a part of is. This is why the dimensions of purpose, power and gender become suppressed from our consciousness.

scholarly journals Design and construction of a continuous impregnation apparatus of woven fibres, using non-meshing double-sinusoidal toothed rollers

2020 ◽  
Vol 317 ◽  
pp. 01006
Author(s):  
G. Vasileiou ◽  
C. Vakouftsis ◽  
N. Rogkas ◽  
S. Tsolakis ◽  
P. Zalimidis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Theoretical Calculations ◽  
Dimensional Space ◽  
Continuous Production ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Three Dimensions ◽  
Main Challenge ◽  
Complete Failure ◽  
As Stress

Resin-impregnated fibres are extensively used in a variety of industrial applications as is demonstrated in the literature. Resin-fibre impregnation techniques are used in order to create homogeneous macro – materials and to take full advantage of the mechanical properties of the fibrous reinforcement (i.e. carbon, glass, organic or ceramic fibres). However, achieving highly impregnated fibres is proven quite challenging especially in continuous production techniques that are required for large production rates. The main challenge lies in achieving complete impregnation of the tightly arranged fibres mainly referring to the formed yarns containing multiple fibres, sometimes even twisted. This results in partially impregnated materials containing cavities that tend to exhibit inferior mechanical properties compared to the theoretical calculations, which assume fully impregnated materials. These cavities often lead to crack generation, acting as stress concentration sites, resulting in complete failure of the material at macro-level. In this paper a novel technique for continuous production of fully impregnated woven fibres is presented using non – meshing, co – rotating rollers. A laboratory-scale apparatus is designed and described thoroughly in the context of this work. The method resembles pultrusion in the sense that a reinforcement plain fibre mesh (glass) is co–processed with the liquid resin through a pair of co–rotating toothed rollers to produce a continuously reinforced 3D tape. The surface of the rollers is produced from a double-sinusoidal toothed surface (rack) using the Theory of Gearing in three-dimensions, which imposes significant differential sliding of the fibres without differential tension and facilitates fibre wetting. The geometry of the rollers is calculated not to damage the unprocessed fibres, while facilitating local widespreading of the stranded fibres in the three – dimensional space leading to the resin being able to fully penetrate the reinforcing fibre material.

On the Interpretation of Vowel “Quality”: The Dimension of Rounding

1989 ◽  
Vol 19 (1) ◽  
pp. 24-30 ◽  
Author(s):  
Leigh Lisker
Keyword(s):  
Vocal Tract ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Vowel Space ◽  
Tongue Position ◽  
Two Measures ◽  
The One ◽  
Jaw Position ◽  
Three Dimensional Space

The usual description of vowels in respect to their “phonetic quality” requires the linguist to locate them within a so-called “vowel space,” apparently articulatory in nature, and having three dimensions labeled high-low (or close-open), front-back, and unrounded-rounded. The first two are coordinates of tongue with associated jaw position, while the third specifies the posture of the lips. It is recognized that vowels can vary qualitatively in ways that this three-dimensional space does not account for. So, for example, vowels may differ in degree of nasalization, and they may be rhotacized or r-colored. Moreover, it is recognized that while this vowel space serves important functions within the community of linguists, both the two measures of tongue position and the one for the lips inadequately identify those aspects of vocal tract shapes that are primarily responsible for the distinctive phonetic qualities of vowels (Ladefoged 1971). With all this said, it remains true enough that almost any vowel pair of different qualities can be described as occupying different positions with the space. Someone hearing two vowels in sequence and detecting a quality difference will presumably also be able to diagnose the nature of the articulatory shift executed in going from one vowel to the other.

Sign in / Sign up

Export Citation Format

Share Document