Misperceiving extents in the medial plane: The paradox of Shepard's tables illusion.

2004 ◽  
pp. 97-123 ◽  
Author(s):  
Boris Crassini ◽  
Christopher J. Best ◽  
Ross H. Day
Keyword(s):  
Medial Plane

scholarly journals Safe Zone for Percutaneous Screw Fixation - Talonavicular Fusion

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0043
Author(s):  
Ashish Shah ◽  
Sung Lee ◽  
Sameer Naranje ◽  
Zachariah Pinter ◽  
Robert Stibolt ◽  
...  
Keyword(s):  
Medial Branch ◽  
Screw Insertion ◽  
Anterior Branch ◽  
Bony Landmarks ◽  
Medial Plane ◽  
Extensor Hallucis Longus ◽  
Hindfoot Deformities ◽  
Fresh Frozen ◽  
Optimal Fusion ◽  
Neurovascular Structures

Category: Hindfoot Introduction/Purpose: Talonavicular fusion has been established as a reliable intervention for degenerative, inflammatory, and traumatic joint lesions as well as hindfoot deformities. In order to achieve optimal fusion, various versions of the procedure have been introduced in literature and have remained a topic of contention, with the most common variation involving the insertion of 1 to 3 screws dorsomedially and dorsolaterally. Dorsolateral screw placements commonly cause neurovasculature injury. The purpose of our cadaveric study was first to establish the safety of the dorsolateral percutaneous screw insertion in relation to these dorsal neurovascular structures, and then subsequently to standardize the ideal placement of the dorsolateral screw by comparing two insertion sites based on consistent bony landmarks. Methods: Ten fresh-frozen cadaver legs amputated at the knee were used for this study. Percutaneous cannulated screws were inserted to perform isolated talonavicular arthrodesis. The screws were inserted at 3 consistent sites: “medial screw” at dorsomedial navicular where it intersected at the medial plane of the first cuneiform, “central screw” at the edge of dorsal navicular between medial and intermediate cuneiforms, and “lateral screw” at the edge of dorsal navicular between intermediate and lateral cuneiforms. Superficial and deep dissections were carried out to identify any injured nerves, arteries, and tendons. Results: The mean age at death in our sample of cadavers was 80.1 ± 7.5 years (range 68 to 92) and had the BMI of 21.8 ± 2.4 (range 18.1 to 25.1). There were 5 males (50.0%) and 5 females (50.0%). The medial screw injured the anterior tibialis tendon in 2 cases (20.0%), the central screw injured the extensor hallucis longus tendon in 3 cases (30.0%), and the lateral screw injured the anterior branch of SPN, lateral branch of SPN, and medial branch of DPN once each in a total of 3 cases (30.0%). Conclusion: TN fusion with central screw placement at the interspace between the medial and intermediate cuneiforms protects the neurovasculatures of the foot to a superior extent than lateral screws between the intermediate and lateral cuneiforms.

A reconnaissance of skeletal crystallography in rhombiferans, diploporans, and paracrinoids

2004 ◽  
Vol 78 (6) ◽  
pp. 1154-1162 ◽  
Author(s):  
Brian E. Bodenbender ◽  
Erik J. Hiemstra
Keyword(s):  
Crystallographic Data ◽  
Crystallographic Axis ◽  
Axis Orientation ◽  
Medial Plane ◽  
Taxonomic Groups

We characterized the skeletal crystallography of representatives of nine rhombiferan, three diploporan, and three paracrinoid species. Crystallographic data from these groups are similar to data from previous studies of crinoids, echinoids, and blastoids in that 1) orientations ofcaxes are consistent within species and within higher taxonomic groups; 2)caxes typically are oriented subparallel to the medial plane of their respective plates; and 3) the inclination of axes within the medial plane varies between taxa. Rhombiferancaxes are oriented normal to plate surfaces whereas diploporancaxes are tangential to plate surfaces. Paracrinoids more closely resemble diploporans in having irregular patterns of thecal plating but theircaxes are approximately perpendicular to plate surfaces as in rhombiferans.In contrast tocaxes,aaxes in all specimens show little regularity and cannot be distinguished from random orientations.The rhombiferanCaryocrinites ornatusdisplays minor differences in the inclinations ofcaxes depending on the location of skeletal elements on the theca. Plates at the base of the theca have slightly aborally inclined axes, whereas distal plates have axes inclined slightly adorally. This pattern matches orientations in some early crinoids, suggesting similarities between rhombiferans and crinoids in development or skeletal construction.Skeletal crystallography in various echinoderms can be compared in light of hypotheses of homology proposed in the Extraxial-Axial Theory (EAT). Skeletal elements homologized under the EAT do not correspond to any particular crystallographic axis orientation, suggesting that the homologies proposed in the EAT encompass significant underlying skeletal variation.

scholarly journals Macroscopic Examination of Multiple-Shot Cattle Heads—An Animal Welfare Due Diligence Tool for Abattoirs Using Penetrating Captive Bolt Devices?

Animals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 328 ◽  
Author(s):  
Andrew Grist ◽  
Toby G. Knowles ◽  
Stephen Wotton
Keyword(s):  
Animal Welfare ◽  
Anatomical Variation ◽  
Due Diligence ◽  
Proof Of Concept ◽  
Training Material ◽  
The United Kingdom ◽  
Medial Plane ◽  
Multiple Shot ◽  
Determining Factor ◽  
Macroscopic Examination

Ideally, the application of a penetrating captive bolt device to render cattle immediately unconscious prior to slaughter would be 100% effective. Unfortunately, due to various factors this is not always the case. This paper examined, as an initial proof of concept, 12 bovine heads which had received more than one shot from a penetrating captive bolt, collected from various abattoirs within the United Kingdom. The heads were frozen to facilitate splitting on the medial plane to prevent distortion of soft tissue and each sagittal section was examined macroscopically to ascertain if this method could be used to determine the reasons for repeated stun attempts. In 10 out of 12 heads, shot placement was the determining factor, in one other head it was felt that anatomical variation was the reason and the twelfth head demonstrated signs of gun malfunction as the likely cause. This work provides evidence for a larger trial to facilitate the production of guidance for the abattoir industry, the Animal Welfare Officer and regulators on the examination of heads as part of an investigation of failures of a mechanical stunning system and to provide training material for slaughter staff tasked with effectively stunning cattle.

scholarly journals The dynamical stresses produced in a thick plate by the action of surface forces

1958 ◽  
Vol 3 (4) ◽  
pp. 153-163 ◽  
Author(s):  
J. Fulton ◽  
I. N. Sneddon
Keyword(s):  
Thick Plate ◽  
Harmonic Wave ◽  
The Other ◽  
Two Dimensional ◽  
Direction Parallel ◽  
Free Surfaces ◽  
Phase Velocities ◽  
Medial Plane ◽  
Distribution Of Stress ◽  
Propagation Of Elastic Waves

The first discussion of the propagation of elastic waves in a thick plate was given by Lamb [1] for the two-dimensional problem of a harmonic wave travelling in a direction parallel to the medial plane of the plate. Lamb derived equations relating the thickness of the plate to the phase velocities of two types of wave, one symmetric with respect to the medial plane and the other antisymmetric. The symmetric modes of propagation introduced by Lamb have been studied by Holden [2] and the antisymmetric modes have been studied by Osborne and Hart [3]. More recently Pursey [4] has shown how the amplitude of the disturbance is related to a given distribution of stress, varying harmonically with time, applied to the free surfaces of the plate; two types of source are considered by Pursey, one producing a two-dimensional field of the Lamb type, and the other having circular symmetry about an axis normal to the surface of the plate.

An Experimental Study of the Near-Wake Structure of a Cylinder Undergoing Combined Translational and Rotational Oscillatory Motions

2010 ◽  
Author(s):  
Mehdi Nazarinia ◽  
Mark C. Thompson ◽  
John Sheridan ◽  
David Lo Jacono
Keyword(s):  
Vortex Shedding ◽  
Near Wake ◽  
Double Row ◽  
Wake Structure ◽  
Single Row ◽  
Rotational Oscillation ◽  
Medial Plane ◽  
Image Velocimetry ◽  
Phase Angles ◽  
Phase Differences

The experimental research reported here uses particle image velocimetry to extend the study of Nazarinia et al. [1], recording detailed vorticity fields in the near-wake of a circular cylinder undergoing combined translational and rotational oscillatory motions. The focus of the present study is to examine the effect of the ratio between the translational and rotational velocities of the cylinder on the synchronization of the near-wake structures. The frequencies are fixed close to that of the natural frequency of vortex shedding. The results are presented for a fixed amplitude of rotational oscillation of 1 radian and a range of ratios between the translational and rotational velocities (VR) = [0.25, 0.5, 1.0, 1.5]. In particular, it was found that varying the VR value changed the near-wake structure. The results show that at lower values of VR = 0.25, for all of the phase differences examined, the vortices are shed in a single-row 2S mode aligned in the medial plane with a slight offset from the centerline and also synchronized with the combined oscillatory motion. As VR increases the vortex shedding mode changes from a 2S single-row to a 2S double-row structure and eventually back to the single-row (at VR = 0.5). Increasing VR further resulted in the appearance of unlocked-on regimes over the range of negative phase angles and a transition from 2S to P + S mode at the in-phase case There was transition back to the 2S with a further decrease of Φ. For a higher VR the range of desynchronization increased.

Study of the Human Pelvis Using CAT-scan: Gender Differences and Anatomy of the Ramus Ossis Ischii

2008 ◽  
Vol 32 (4) ◽  
pp. 385-389 ◽  
Author(s):  
Hendrik van de Meent ◽  
Harry Jansen ◽  
Harmen van der Linde
Keyword(s):  
Gender Differences ◽  
Soft Tissue ◽  
Horizontal Distance ◽  
Plane Angle ◽  
Men And Women ◽  
Cat Scan ◽  
Medial Plane ◽  
Caucasian Men ◽  
The Difference ◽  
Student’S T

Objective: In a descriptive study we present the CAT-scan norm data of pelvic sizes in Caucasian men and women. The study was performed to investigate possible differences in pelvic sizes between men and women and the inter-individual range of pelvic sizes. The data may be useful as a guide in the development of orthoses and prostheses. Methods: Pelvis CAT-scans of 40 subjects, 20 males (23–66 years) and 20 females (20–72 years) were investigated. The research was approved by the regional ethics committee. Results: The angle of the ramus ossis ischii (ROI) with the line of progression in the transverse plane (angle a) was 38.6° (SD 3.4) in females and 31.8° (SD 4.4) in males. This difference was statistically significant (Student's t-test ( p < 0.0001). The ROI angle in the coronal plane (angle b) was negative or zero both in males and females. The horizontal distance between the medial border of the ROI and the lateral border of the femur (RF distance) was slightly smaller in females (95 mm) compared to males (107 mm), but this difference was not statistically significant. The distance between the midfemoral line and the anterior surface of the leg was also slightly smaller in females (89 mm) than in males (106 mm) but the difference was not statistically significant. We found a linear relation between the total AP soft tissue distance and the soft tissue circumference of the proximal leg at the level of the ROI. Conclusion: There are significant gender differences in pelvic size and shape. The medial plane of the ROI is not in a slight angle of inclination towards the midline but appears to be zero. The medial contour of the ROI in the AP direction is slightly curved.

Worthenopora: an unusual cryptostome (Bryozoa) that looks like a cheilostome

1991 ◽  
Vol 65 (4) ◽  
pp. 648-661 ◽  
Author(s):  
Steven J. Hageman
Keyword(s):  
North America ◽  
Water Column ◽  
Secondary Structures ◽  
Growth Patterns ◽  
Wall Structure ◽  
Illinois Basin ◽  
Trade Off ◽  
Growth Sequence ◽  
Column Space ◽  
Medial Plane

Worthenopora is a Mississippian cryptostome bryozoan genus with certain characteristics that so closely resemble those of some cheilostomes (Jurassic–Recent) that previous bryozoan experts speculated whether Worthenopora should be assigned to the order Cheilostomata. This raises the question of possible affinities between cryptostomes (class Stenolaemata) and cheilostomes (class Gymnolaemata). Based on wall structure, growth sequence, zooecial shape, and secondary structures such as stylets, Worthenopora is here shown to be a stenolaemate, assignable to the suborder Ptilodictyina with other bifoliate cryptostomes. Although the exterior appearance of Worthenopora superficially resembles some cheilostomes, it represents rather limited divergence from more typical bifoliate growth patterns. Additionally, presence of characteristics such as elongate zooecia with thin exozones, cuticular medial plane, and distinctive exterior ridges justifies retention of the monogeneric family Worthenoporidae. Three species (W. spatulata, W. spinosa, and W. valmeyerensis), known only from North America and primarily restricted to the Illinois Basin, are recognized. Analysis of apertural spacing in these species suggests a trade-off between feeding efficiency and occupation of water-column space. Worthenopora valmeyerensis is considered a hypermorphic derivative of W. spinosa.

Statistical Tolerance Allocation for Tab-Slot Assemblies Utilizing Tolerance-Maps

2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Gaurav Ameta ◽  
Joseph K. Davidson ◽  
Jami J. Shah
Keyword(s):  
Tolerance Allocation ◽  
Probabilistic Representation ◽  
Worst Case ◽  
Material Condition ◽  
Geometric Tolerances ◽  
Constant Size ◽  
Medial Plane ◽  
Statistical Tolerance ◽  
Tolerance Assignment ◽  
Case Basis

A new mathematical model for representing the geometric variations of tabs/slots is extended to include probabilistic representations of 1D clearance. The 1D clearance can be determined from multidimensional variations of the medial-plane for a slot or a tab, and from variations of both medial-planes in a tab-slot assembly. The model is compatible with the ASME/ANSI/ISO Standards for geometric tolerances. Central to the new model is a Tolerance-Map (Patent No. 6963824) (T-Map), a hypothetical volume of points that models the range of 3D variations in location and orientation for a segment of a plane (the medial-plane), which can arise from tolerances on size, position, orientation, and form. Here it is extended to model the increases in yield that occur when the optional maximum material condition (MMC) is specified and when tolerances are assigned statistically rather than on a worst-case basis. The frequency distribution of 1D clearance is decomposed into manufacturing bias, i.e., toward certain regions of a Tolerance-Map, and into a geometric bias that can be computed from the geometry of multidimensional T-Maps. Although the probabilistic representation in this paper is built from geometric bias, and it is presumed that manufacturing bias is uniform, the method is robust enough to include manufacturing bias in the future. Geometric bias alone shows a greater likelihood of small clearances than large clearances between an assembled tab and slot. A comparison is made between the effects of specifying the optional MMC and not specifying it with the tolerance that determines the allowable variations in position of a tab, a slot, or of both in a tab-slot assembly. Statistical tolerance assignment for the tab-slot assembly is computed based on initial worst-case tolerances and for (a) constant size of tab and slot at maximum material condition, and (b) constant virtual-condition size.

Apparent Distance in a Horizontal Plane with Tactile-kinesthetic Stimuli

1964 ◽  
Vol 16 (3) ◽  
pp. 277-281 ◽  
Author(s):  
Robert S. Davidon ◽  
Mei-Fang Hsieh Cheng
Keyword(s):  
Line Segment ◽  
Horizontal Plane ◽  
Visual Illusion ◽  
Space Perception ◽  
Apparent Distance ◽  
Frame Of Reference ◽  
Perceptual Representation ◽  
Medial Plane

In the study of active tactile-kinesthetic space perception apparent distance has been found to vary as a function of the direction of the line segment in a horizontal plane. The present data indicate that the error is not consistently related to the same frame of reference as the visual illusion. Rather, with movement of the extended arm to determine the relative distances between pairs of points, radial distances are overestimated in relation to tangential ones, whether parallel or perpendicular to the medial plane. Interpretations are in terms of kinesthetic stimulus patterns and the structure of perceptual representation.

scholarly journals The advanced model definition and analysis of orthodontic parameters on 3D digital models

2017 ◽  
Vol 145 (1-2) ◽  
pp. 49-57 ◽  
Author(s):  
Nemanja Majstorovic ◽  
Srdjan Zivkovic ◽  
Branislav Glisic
Keyword(s):  
Computer Aided Design ◽  
Basic Element ◽  
T Test ◽  
Occlusal Plane ◽  
Digital Models ◽  
Lower Jaw ◽  
Medial Plane ◽  
Analysis And Synthesis ◽  
Plane Displacement ◽  
3D Digital Models

Introduction/Objective. Digital 3D modeling is slowly becoming an everyday orthodontic practice, and after two decades of research and development it is a basic element of e-orthodontics. The aim of this study was development and use of geometric entities on 3D digital models for diagnosing, planning and monitoring of orthodontic therapy, by using CAD (computer aided design) systems. Methods. Statistical analysis and synthesis of 54 orthodontic parameters (28 in the upper and 26 in the lower jaw), defining three hypotheses and their testing, the application of the t-test. Results. All three hypotheses are confirmed, convenience of using geometric entities, higher accuracy of 3D digital models, and more substantial displacement of teeth in the first six months of therapy (Student?s t-test). After the first six months, distances in the x?y plane (occlusal plane) were bigger in both the upper and the lower jaw; additionally, the distances in the y?z plane (medial plane) decreased on the left and right side, so we can say that the first phase of therapy had success and that both jaws are wider. At the next four controls, parameters showed slight progress that was not statistically significant. Overall, after 11 months of therapy, there was a considerable improvement in the x?y plane, while changes in distances of clinical crown heights were very small. This could be explained by the fact that, during therapy, by using different arches, upper molars were pushed inside, toward the palate. Analyzing 3D computer models, we could notice that in this plane displacement of the upper left first molar was larger. Conclusion. The use of geometric entities for defining orthodontic parameters gives us new possibilities for accurate and reliable analysis of patient?s orthodontic condition.

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