scholarly journals Perceptual Properties of the Poisson Effect

2021 ◽  
Vol 11 ◽  
Author(s):  
Takahiro Kawabe
Keyword(s):  
Elastic Material ◽  
Relative Magnitude ◽  
Deformation Pattern ◽  
Relative Deformation ◽  
Poisson Effect ◽  
Image Deformation ◽  
Force Direction ◽  
Horizontal Expansion ◽  
Direction Judgment ◽  
The Brain

When an elastic material (e.g., fabric) is horizontally stretched (or compressed), the material is compressed (or extended) vertically – so-called the Poisson effect. In the different case of the Poisson effect, when an elastic material (e.g., rubber) is vertically squashed, the material is horizontally extended. In both cases, the visual system receives image deformations involving horizontal expansion and vertical compression. How does the brain disentangle the two cases and accurately distinguish stretching from squashing events? Manipulating the relative magnitude of the deformation of a square between horizontal and vertical dimensions in the two-dimensional stimuli, we asked observers to judge the force direction in the stimuli. Specifically, the participants reported whether the square was stretched or squashed. In general, the participant’s judgment was dependent on the relative deformation magnitude. We also checked the anisotropic effect of deformation direction [i.e., horizontal vs. vertical stretching (or squashing)] and found that the participant’s judgment was strongly biased toward horizontal stretching. We also observed that the asymmetric deformation pattern, which indicated the specific context of force direction, was also a strong cue to the force direction judgment. We suggest that the brain judges the force direction in the Poisson effect on the basis of assumptions about the relationship between image deformation and force direction, in addition to the relative image deformation magnitudes between horizontal and vertical dimensions.

The Influence of Die Geometry on the Radial Extrusion Processes with AA 6063 Aluminium Alloy

2006 ◽  
Vol 519-521 ◽  
pp. 937-942
Author(s):  
Dong Hwan Jang ◽  
J.H. Ok ◽  
H.S. Koo ◽  
G.M. Lee ◽  
Beong Bok Hwang
Keyword(s):  
Process Parameters ◽  
Material Flow ◽  
Deformation Pattern ◽  
Relative Deformation ◽  
Die Geometry ◽  
Single Action ◽  
Pressing Process ◽  
Major Process ◽  
Forming Characteristics ◽  
Gap Height

The rigid-plastic finite element method has been applied to three variants of radial extrusion processes to investigate the influence of die geometry on the material flow into the flange gap. Case I involves forcing a cylindrical billet against a flat die, which is a single action pressing process. In case II, another single action pressing process, the upper punch forces a billet against a stationary punch recessed in the lower die. Both the upper and lower punches move together in Case III toward the center of billet at the same speed with a double action tool. Major process parameters are identified as the relative gap height and the die corner radius in constant relative deformation. The relative gap height is defined as the ratio of gap height to billet diameter. Extensive simulation work for various combinations of process parameter value has been performed and then the main characteristics of the deformation patterns of each case are observed to define the terms which represent the forming characteristics of the flange in radial extrusion processes in terms of separation height, asymmetric ratio of height, and asymmetric ratio of angle, respectively. The effect of major process parameters on the material flow into the flange gap has been also analyzed in terms of flange radius and flange angle. The effect of frictional condition on the separation height has been also analyzed to investigate the edge separation of flange from the flat die. AA 6063 aluminum alloy is selected as a model material throughout the analysis. Simple comparison between AA 6063 and AISI 1006 steel has been also made to investigate the effect of material selection on the deformation pattern, especially in terms of separation height in Case I and asymmetry in Case II, respectively.

scholarly journals Why Bilateral Damage Is Worse than Unilateral Damage to the Brain

2013 ◽  
Vol 25 (12) ◽  
pp. 2107-2123 ◽  
Author(s):  
Anna C. Schapiro ◽  
James L. McClelland ◽  
Stephen R. Welbourne ◽  
Timothy T. Rogers ◽  
Matthew A. Lambon Ralph
Keyword(s):  
Relative Magnitude ◽  
Striking Difference ◽  
Feedforward Networks ◽  
Intact Side ◽  
Computational Explanation ◽  
Sensory Motor ◽  
Lesion Studies ◽  
The Difference ◽  
Bilateral Lesions ◽  
The Brain

Human and animal lesion studies have shown that behavior can be catastrophically impaired after bilateral lesions but that unilateral damage often produces little or no effect, even controlling for lesion extent. This pattern is found across many different sensory, motor, and memory domains. Despite these findings, there has been no systematic, computational explanation. We found that the same striking difference between unilateral and bilateral damage emerged in a distributed, recurrent attractor neural network. The difference persists in simple feedforward networks, where it can be understood in explicit quantitative terms. In essence, damage both distorts and reduces the magnitude of relevant activity in each hemisphere. Unilateral damage reduces the relative magnitude of the contribution to performance of the damaged side, allowing the intact side to dominate performance. In contrast, balanced bilateral damage distorts representations on both sides, which contribute equally, resulting in degraded performance. The model's ability to account for relevant patient data suggests that mechanisms similar to those in the model may operate in the brain.

scholarly journals FREE AND FORCED VIBRATIONS OF SHELLS OF VARIOUS SHAPES, TAKING INTO ACCOUNT THE VARIABILITY OF THE NON-LINEAR ELASTIC MATERIAL

2020 ◽  
Vol 3 (1) ◽  
pp. 70-75
Author(s):  
I. Sadygov
Keyword(s):  
Elastic Material ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Forced Vibrations ◽  
Relative Deformation ◽  
Dimensionless Frequency ◽  
Building Structures ◽  
Space Technology ◽  
Free And Forced Vibrations ◽  
Nonlinear Elastic

the article considers issues of shell vibrations, which are widely used in various industries and construction. Shells serve as elements of building structures with large spans. The chapter “Introduction” discussed issues related to the use of shells in all areas of industry, in aviation, rocket and space technology, railway transport, in the oil and gas industry and provides examples of shells for use in ceilings of circuses, stations, hangars; in industry: shells of rotation used as tanks, containers, columns, reactors, etc. In the section “Materials and research methods” free and forced vibrations of shells of variable thickness made out of nonlinear elastic material reviewed. In shell calculations the Kirchhoff – Law hypothesis was used. It was found that, during vibrations, the shells experience relative deformation of elongation and shear of the surface with coordinates (x, y), as well as bending and torsion strains. It is established that vibrations in the shells lead to a rotation of the main directions of elasticity and regarding to the adopted coordinate axis to angle θ, and the elastic constants of the material depend on the elastic constant Biy – the main directions of the nonlinear elastic shells. When solving the system of equations of motion of the shell relative to the displacements arising in it during vibration, based on theory R and various methods. The values of the dimensionless frequency parameter for a spherical shell taking into account changes in its curvature, variability and thickness of elastic properties are obtained.

scholarly journals Physiological inferences derived from human and comparative anatomy respecting the origins of the nerves, the cerebellum, and the striated bodies

1843 ◽  
Vol 4 ◽  
pp. 472-473 ◽  
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Medulla Oblongata ◽  
Comparative Anatomy ◽  
Relative Magnitude ◽  
Posterior Surface ◽  
Great Similarity ◽  
The Brain

The author remarks that those parts of the nervous system which are concerned in motion and in sensation exhibit a great similarity in all vertebrate animals. To the first of these functions belong the anterior and middle portions of the spinal cord and medulla oblongata, including the anterior pyramids, the crura cerebri, and some fibres leading to the corpora striata and the convolutions, and also the cerebellum. To the function of sensation belong the posterior surface of the spinal cord, the posterior and lateral portions of the medulla oblongata, including the posterior pyramids, the ventricular cords, and the fourth and third ventricles. From a general comparison of the relative magnitude and structure of these several parts in the different classes of vertebrated animals, the author infers that only a very small portion of the brain is necessary for the origins of the nerves, their respective faculties being generally derived near the place at which they leave the brain. These origins are traced in various cases, where, from peculiarities of arrangement or of destination, they present certain remarkable differences of situation.

scholarly journals How growing tumour impacts intracranial pressure and deformation mechanics of brain

2021 ◽  
Vol 8 (9) ◽  
Author(s):  
Ali Ahmed ◽  
Muhammad Uzair UlHaq ◽  
Zartasha Mustansar ◽  
Arslan Shaukat ◽  
Lee Margetts
Keyword(s):  
Brain Parenchyma ◽  
Deformation Pattern ◽  
Diagnostic Purpose ◽  
Midline Shift ◽  
Correlation Relationship ◽  
Brain Physiology ◽  
Initial Stage ◽  
Deformation Mechanics ◽  
Relationship Of ◽  
The Brain

Brain is an actuator for control and coordination. When a pathology arises in cranium, it may leave a degenerative, disfiguring and destabilizing impact on brain physiology. However, the leading consequences of the same may vary from case to case. Tumour, in this context, is a special type of pathology which deforms brain parenchyma permanently. From translational perspective, deformation mechanics and pressures, specifically the intracranial cerebral pressure (ICP) in a tumour-housed brain, have not been addressed holistically in literature. This is an important area to investigate in neuropathy prognosis. To address this, we aim to solve the pressure mystery in a tumour-based brain in this study and present a fairly workable methodology. Using image-based finite-element modelling, we reconstruct a tumour-based brain and probe resulting deformations and pressures (ICP). Tumour is grown by dilating the voxel region by 16 and 30 mm uniformly. Cumulatively three cases are studied including an existing stage of the tumour. Pressures of cerebrospinal fluid due to its flow inside the ventricle region are also provided to make the model anatomically realistic. Comparison of obtained results unequivocally shows that as the tumour region increases its area and size, deformation pattern changes extensively and spreads throughout the brain volume with a greater concentration in tumour vicinity. Second, we conclude that ICP pressures inside the cranium do increase substantially; however, they still remain under the normal values (15 mmHg). In the end, a correlation relationship of ICP mechanics and tumour is addressed. From a diagnostic purpose, this result also explains why generally a tumour in its initial stage does not show symptoms because the required ICP threshold has not been crossed. We finally conclude that even at low ICP values, substantial deformation progression inside the cranium is possible. This may result in plastic deformation, midline shift etc. in the brain.

Linking Visual Attention and Number Processing in the Brain: The Role of the Temporo-parietal Junction in Small and Large Symbolic and Nonsymbolic Number Comparison

2007 ◽  
Vol 19 (11) ◽  
pp. 1845-1853 ◽  
Author(s):  
Daniel Ansari ◽  
Ian M. Lyons ◽  
Lucia van Eimeren ◽  
Fei Xu
Keyword(s):  
Response Times ◽  
Neural Correlates ◽  
Relative Magnitude ◽  
Number Processing ◽  
Subitizing Range ◽  
Number Comparison ◽  
Neuro Imaging ◽  
The Right ◽  
The Brain

There exists a long-standing debate regarding whether small and large numerosities engage different networks of processing. The ability to rapidly enumerate small (1–4) numerosities is referred to as “subitizing” and is thought to be qualitatively different from large numerosity processing. Functional neuro-imaging studies have attempted to dissociate neural correlates of small and large number processing by contrasting subitizing with counting of numerosities just outside the subitizing range. In the present study, we used functional magnetic resonance imaging (fMRI) to contrast the processing of numerosities in the “subitizing range” with numerosities requiring estimation. Participants compared sequentially presented slides of either dots or Arabic numerals for their relative magnitude. We show that comparison of nonsymbolic numerosities in the subitizing range led to activation of the right temporo-parietal junction, while at the same time this region was found to be suppressed during large numerosity processing. Furthermore, relative suppression of this region was strongly associated with faster response times. In previous studies, this region has been implicated in stimulus-driven attention.We therefore contend that activation of the temporo-parietal junction during small number processing and the suppression thereof during large numerosity comparisons reflects differential reliance on stimulus-driven versus goal-directed attentional networks in the brain.

scholarly journals Contributions towards determining the weight of the brain in the different races of man

1868 ◽  
Vol 16 ◽  
pp. 236-241
Keyword(s):  
Specific Gravity ◽  
Human Brain ◽  
Relative Magnitude ◽  
Races Of Mankind ◽  
Human Skulls ◽  
Variable Condition ◽  
The Brain

It would naturally be expected that great attention had been directed to the human brain, the organ of mental manifestation. Still little has been done to ascertain its relative magnitude in the different races of mankind. Opportunities for examining exotic brains are rare, and it is only by gauging the internal capacities of human skulls, and deducing the weight of the brain, that data can be obtained. The inferiority of this method is not so clear as has been assumed, since we are able to fix upon an unchangeable substance of definite specific gravity for the purpose of this gauging, whereby we compensate for the variable condition of the brain, depending upon disease and other causes, and the immediate occasion of death.

scholarly journals Deformation - strength parameters of arteries of the brain in the ii period of mature age

2019 ◽  
Vol 10 (1) ◽  
pp. 41-46
Author(s):  
V. N. Nikolenko ◽  
O. A. Fomkina
Keyword(s):  
Cerebral Arteries ◽  
Testing Machine ◽  
Vascular Wall ◽  
Biomechanical Properties ◽  
Relative Deformation ◽  
Tensile Testing Machine ◽  
Average Value ◽  
Basilar Arteries ◽  
Biomechanical Parameters ◽  
The Brain

The aim of research - to identify the features of the biomechanical parameters of the arteries of the brain in the II period of adulthood. Materials and methods. The samples of anterior (ACA), middle (MCA), posterior cerebral (PCA), posterior connective (PCoA), basilar arteries (BA) and intracranial parts of vertebral arteries (VA) seized at autopsy of 40 corpses of men andwomen aged 35-60 years were studied. In the longitudinal tension experiment on the tensile testing machine Tira Test studied the overall strength, tensile strength, maximum relative deformation and young's modulus of walls.Results. The paper describes the average values and variability parameters of the studied biomechanical parameters of arteries. The results of the comparative analysis with the average values typical for the population of adults aged 21-90 years are presented. Conclusion. Biomechanical properties of cerebral arteries are characterized by significant variability. The least changeable is the overall strength of the artery wall. The data obtained differ from the average values typical for the population of adults aged 21-90 years. The greatest differences were found for the ultimate strength of the vascular wall. In the II period of adulthood, this parameter in MCA, PCA, BA, ACA and BA is 8-15% more, and in PCoA is 22% less than the average value.

scholarly journals The Verification of Hybrid Image Deformation algorithm for PIV

2016 ◽  
Vol 14 (1) ◽  
pp. 48-52
Author(s):  
Jan Novotný ◽  
Ludmila Nováková
Keyword(s):  
Particle Image ◽  
Iterative Scheme ◽  
Peak Position ◽  
Relative Deformation ◽  
Accurate Calculation ◽  
Image Deformation ◽  
Advantages And Disadvantages ◽  
Image Velocimetry ◽  
Particle Image Velocimetry Method ◽  
Signal Peak

Abstract The aim of this paper was to test a newly designed algorithm for more accurate calculation of the image displacement of seeding particles when taking measurement using the Particle Image Velocimetry method. The proposed algorithm is based on modification of a classical iterative approach using a three-point subpixel interpolation and method using relative deformation of individual areas for accurate detection of signal peak position. The first part briefly describes the tested algorithm together with the results of the performed synthetic tests. The other part describes the measurement setup and the overall layout of the experiment. Subsequently, a comparison of results of the classical iterative scheme and our designed algorithm is carried out. The conclusion discusses the benefits of the tested algorithm, its advantages and disadvantages.

scholarly journals Three-Dimensional Structure of Dendritic Spines Revealed by Volume Electron Microscopy Techniques

2021 ◽  
Vol 15 ◽  
Author(s):  
Laxmi Kumar Parajuli ◽  
Masato Koike
Keyword(s):  
Electron Microscopy ◽  
Synaptic Transmission ◽  
Three Dimensional ◽  
Morphological Characteristics ◽  
Structural Diversity ◽  
Time Frame ◽  
Relative Magnitude ◽  
Dimensional Structure ◽  
Synaptic Ultrastructure ◽  
The Brain

Electron microscopy (EM)-based synaptology is a fundamental discipline for achieving a complex wiring diagram of the brain. A quantitative understanding of synaptic ultrastructure also serves as a basis to estimate the relative magnitude of synaptic transmission across individual circuits in the brain. Although conventional light microscopic techniques have substantially contributed to our ever-increasing understanding of the morphological characteristics of the putative synaptic junctions, EM is the gold standard for systematic visualization of the synaptic morphology. Furthermore, a complete three-dimensional reconstruction of an individual synaptic profile is required for the precise quantitation of different parameters that shape synaptic transmission. While volumetric imaging of synapses can be routinely obtained from the transmission EM (TEM) imaging of ultrathin sections, it requires an unimaginable amount of effort and time to reconstruct very long segments of dendrites and their spines from the serial section TEM images. The challenges of low throughput EM imaging have been addressed to an appreciable degree by the development of automated EM imaging tools that allow imaging and reconstruction of dendritic segments in a realistic time frame. Here, we review studies that have been instrumental in determining the three-dimensional ultrastructure of synapses. With a particular focus on dendritic spine synapses in the rodent brain, we discuss various key studies that have highlighted the structural diversity of spines, the principles of their organization in the dendrites, their presynaptic wiring patterns, and their activity-dependent structural remodeling.

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