scholarly journals On the Applicability of Stereological Methods for the Modelling of a Local Plastic Deformation in Grained Structure: Mathematical Principles

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 697
Author(s):  
Stanislav Minárik ◽  
Maroš Martinkovič
Keyword(s):  
Structural Changes ◽  
Local Deformation ◽  
Cross Sectional ◽  
Initial Shape ◽  
Structure Deformation ◽  
Sectional Plane ◽  
Single Grain ◽  
Grain Surface ◽  
Local Plastic Deformation ◽  
Structure Orientation

Analysis of systems and structures from their cross-sectional images finds applications in many branches. Therefore, the question of content, quantity, and accuracy of information obtained from various techniques based on cross-sectional views of structures is particularly important. Application of conventional techniques for two-dimensional imaging on the analysis of structure from a cross-sectional image is limited. The reason for this limitation is the fact that these techniques use a fixed cross-sectional plane and therefore cannot check the 3D structural changes caused by deformation. Geometric orientation of a grained structure must be considered when data, scanned from a cross section, is processed in order to obtain information about local deformation in this structure. The so-called degree of structure orientation in 3D can be estimated experimentally from the cross-sectional image of the structure by the statistical (Saltykov) method of oriented testing lines. Subsequently if the correlation between orientation and deformation were to be known a detailed map of local deformation in the structure could be revealed. Unfortunately, exact theoretical works dealing with the assessment of local deformation by means of change of structure orientation in 3D are still missing. Our work seeks to partially remove this shortcoming. In our work we are interested in how the transformation of the image of a grained structure in a cross-sectional plane reflects structure deformation. An initial shape of grains is assumed which is transformed into a deformed shape by analytic calculation. We present brief mathematical derivations aimed at the problem of single grain-surface area deformation. The main goal of this work led to the design of a computationally low consuming procedure for quantification of local deformation in a grained structure based on the distortion of the image of this structure in a cross-sectional view.

scholarly journals Extracting Cross-Sectional Clinical Images Based on Their Principal Axes of Inertia

Scanning ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yuzhou Fan ◽  
Liangping Luo ◽  
Marija Djuric ◽  
Zhiyu Li ◽  
Djordje Antonijevic ◽  
...  
Keyword(s):  
Structural Changes ◽  
Cross Sectional ◽  
Clinical Images ◽  
Axis Orientation ◽  
New Approach ◽  
Principal Axes ◽  
Cross Sectional Imaging ◽  
Sectional Plane ◽  
Scanning Session ◽  
Imaging Plane

Cross-sectional imaging is considered the gold standard in diagnosing a range of diseases. However, despite its widespread use in clinical practice and research, no widely accepted method is available to reliably match cross-sectional planes in several consecutive scans. This deficiency can impede comparison between cross-sectional images and ultimately lead to misdiagnosis. Here, we propose and demonstrate a method for finding the same imaging plane in images obtained during separate scanning sessions. Our method is based on the reconstruction of a “virtual organ” from which arbitrary cross-sectional images can be extracted, independent of the axis orientation in the original scan or cut; the key is to establish unique body coordinates of the organ from its principal axes of inertia. To verify our method a series of tests were performed, and the same cross-sectional plane was successfully extracted. This new approach offers clinicians access, after just a single scanning session, to the morphology and structure of a lesion through cross-sectional images reconstructed along arbitrary axes. It also aids comparable detection of morphological and structural changes in the same imaging plane from scans of the same patient taken at different times—thus potentially reducing the misdiagnosis rate when cross-sectional images are interpreted.

scholarly journals Decreased choroidal and scleral thicknesses in highly myopic eyes with posterior staphyloma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Un Chul Park ◽  
Eun Kyoung Lee ◽  
Bo Hee Kim ◽  
Baek-Lok Oh
Keyword(s):  
Choroidal Thickness ◽  
Structural Changes ◽  
Meta Analysis ◽  
Cross Sectional Study ◽  
Pathologic Myopia ◽  
Sectional Study ◽  
Cross Sectional ◽  
Swept Source ◽  
Posterior Staphyloma ◽  
Myopic Maculopathy

AbstractIn this cross-sectional study, we investigated choroidal thickness (CT) and scleral thickness (ST) in highly myopic eyes and their associations with ocular factors. Patients underwent widefield swept-source optical coherence tomography (OCT) to measure the CT and ST at the subfovea and 3000 μm superior, inferior, temporal, and nasal to the fovea and macular curvature. A total of 237 eyes (154 patients) were included. At all five measurement points, thinner CTs and STs were associated with longer axial lengths (r = − 0.548 to − 0.357, all P < 0.001) and greater macular curvatures (r = − 0.542 to − 0.305, all P < 0.001). The CT and ST were significantly thinner in eyes with posterior staphyloma than in those without at all measurement points (all P ≤ 0.006) but did not differ between eyes with the wide macular and narrow macular type of staphyloma. Eyes with myopic maculopathy of category ≥ 3 according to the International Meta-Analysis for Pathologic Myopia classification had significantly thinner CTs and STs than those with category ≤ 2 (all P ≤ 0.005). In highly myopic eyes, a decrease in the CT and ST was more pronounced in eyes with more structural changes, such as longer axial length, steeper macular curvature, and the presence of posterior staphyloma.

scholarly journals Microperimetry-Assessed Functional Alterations and OCT-Changes in Patients after Retinal Detachment Surgery Using Pars Plana Vitrectomy and SF6 Tamponade

Diagnostics ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1157
Author(s):  
María D. Díaz-Barreda ◽  
Isabel Bartolomé-Sesé ◽  
Ana Boned-Murillo ◽  
Antonio Ferreras ◽  
Elvira Orduna-Hospital ◽  
...  
Keyword(s):  
Retinal Detachment ◽  
Pars Plana Vitrectomy ◽  
Structural Changes ◽  
Cross Sectional Study ◽  
Retinal Sensitivity ◽  
Cross Sectional ◽  
Swept Source ◽  
Integrity Assessment ◽  
Integrity Index ◽  
Pars Plana

Background: We study the retinal function measured by macular integrity assessment microperimetry (MAIA) and structural changes assessed by scanning swept source optical coherence tomography (SS-OCT) between healthy individuals and patients undergoing pars plana vitrectomy (PPV) after rhegmatogenous retinal detachment (RRD). Methods: Cross-sectional study. Early Treatment Diabetic Retinopathy Study (ETDRS) grids were measured by SS-OCT and compared with the MAIA parameters. Results: Thirty-eight eyes with RRD (19 macula-on and 19 macula-off) were compared with 113 healthy eyes. The retinal sensitivity and average total threshold were reduced in all sectors in the RRD group; macular integrity index was increased. Macular thicknesses in total retina and ganglion cell layer (GCL)++ protocols were higher in the RRD group in nasal outer (NO) and central (C) sectors and only in C sector for GCL+ protocol. Thicknesses were lower in total retina, GCL++ protocols in the temporal outer (TO) sector and in the GCL+ protocol in NO sector. Best-corrected visual acuity (BCVA) correlated moderately with retinal sensitivity in all sectors and in just several sectors with time between the date of surgery and the test. The central nasal (CN) sector thickness and the average total threshold were higher in the macula-on subgroup. Conclusions: RRD and subsequent surgery results in functional and structural changes, especially in individuals with macular detachment.

The stress generated in a non-dilute suspension of elongated particles by pure straining motion

1971 ◽  
Vol 46 (4) ◽  
pp. 813-829 ◽  
Author(s):  
G. K. Batchelor
Keyword(s):  
Theoretical Formula ◽  
Rigid Sphere ◽  
Cross Sectional ◽  
Outer Flow ◽  
Rigid Particles ◽  
Bulk Stress ◽  
Order Of Magnitude ◽  
Sectional Plane ◽  
Dilute Suspension ◽  
A Minor

In a pure straining motion, elongated rigid particles in suspension are aligned parallel to the direction of the greatest principal rate of extension, provided the effect of Brownian motion is weak. If the suspension is dilute, in the sense that the particles are hydrodynamically independent, each particle of length 2l makes a contribution to the bulk deviatoric stress which is of roughly the same order of magnitude as that due to a rigid sphere of radius l. The fractional increase in the bulk stress due to the presence of the particles is thus equal to the concentration by volume multiplied by a factor of order l2/b2, where 2b is a measure of the linear dimensions of the particle cross-section. This suggests that the stress due to the particles might be relatively large, for volume fractions which are still small, with interesting implications for the behaviour of polymer solutions. However, dilute-suspension theory is not applicable in these circumstances, and so an investigation is made of the effect of interactions between particles. It is assumed that, when the average lateral spacing of particles (h) satisfies the conditions b [Lt ] h [Lt ] l, the disturbance velocity vector is parallel to the particles and varies only in the cross-sectional plane. The velocity near a particle is found to have the same functional form as for an isolated particle, and the modification to the outer flow field for one particle is determined by replacing the randomly placed neighbouring particles by an equivalent cylindrical boundary. The resulting expression for the contribution to the bulk stress due to the particles differs from that for a dilute suspension only in a minor way, viz. by the replacement of log 2l/b by log h/b, and the above suggestion is confirmed. The relative error in the expression for the stress is expected to be of order (log h/b)−1. Some recent observations by Weinberger of the stress in a suspension of glass-fibre particles for which 2l/h = 7·4 and h/2b = 7·8 do show a particle stress which is much larger than the ambient-fluid stress, although the theoretical formula is not accurate under these conditions.

scholarly journals Ultrastructural Adaptation of the Cardiomyocyte to Chronic Mitral Regurgitation

2021 ◽  
Vol 8 ◽  
Author(s):  
Daniella Corporan ◽  
Ana Segura ◽  
Muralidhar Padala
Keyword(s):  
Mitral Regurgitation ◽  
Structural Changes ◽  
Recovery Of Function ◽  
Wall Stress ◽  
Ultrastructural Changes ◽  
Sprague Dawley ◽  
Cross Sectional ◽  
Systolic Volume ◽  
The Impact ◽  
Time Point

Introduction: Mitral regurgitation (MR) imposes volume overload on the left ventricle (LV) and elevates wall stress, triggering its adverse remodeling. Pronounced LV dilation, minimal wall thinning, and a gradual decline in cardiac ejection fraction (EF) are observed. The structural changes in the myocardium that define these gross, organ level remodeling are not known. Cardiomyocyte elongation and slippage have both been hypothesized, but neither are confirmed, nor are the changes to the cardiomyocyte structure known. Using a rodent model of MR, we used immunohistochemistry and transmission electron microscopy (TEM) to describe the ultrastructural remodeling of the cardiomyocyte.Methods: Twenty-four male Sprague-Dawley rats (350–400 g) were assigned to two groups: group (1) rats induced with severe MR (n = 18) and group (2) control rats that were healthy and age and weight matched (n = 6). MR was induced in the beating heart using a 23-G ultrasound-guided, transapical needle to perforate the anterior mitral leaflet, and the rats were followed to 2, 10, and 20 weeks (n = 6/time-point). Echocardiography was performed to quantify MR severity and to measure LV volume and function at each time-point. Explanted myocardial tissue were examined with TEM and immunohistochemistry to investigate the ultrastructural changes.Results: MR induced rapid and significant increase in end-diastolic volume (EDV), with a 50% increase by 2 weeks, compared with control. Rise in end-systolic volume (ESV) was more gradual; however, by 20 weeks, both EDV and ESV in MR rats were increased by 126% compared with control. A significant decline in EF was measured at 10 weeks of MR. At the ultrastructural level, as early as 2 weeks after MR, cardiomyocyte elongation and increase in cross-sectional area were observed. TEM depicted sarcomere shortening, with loss of Z-line and I-band. Desmin, a cytoskeletal protein that is uniformly distributed along the length of the cardiomyocyte, was disorganized and localized to the intercalated disc, in the rats induced with MR and not in the controls. In the rats with MR, the linear registry of the mitochondrial arrangement along the sarcomeres was lost, with mitochondrial fragmentation, aggregation around the nucleus, and irregularities in the cristae.Discussion: In the setting of chronic mitral regurgitation, LV dilatation occured by cardiomyocyte elongation, which manifests at the subcellular level as distinct ultrastructural alterations of the sarcomere, cytoskeleton, and mitochondria. Since the cytoskeleton not only provides tensegrity but has functional consequences on myocyte function, further investigation into the impact of cytoskeletal remodeling on progressive heart failure or recovery of function upon correcting the valve lesion are needed.

scholarly journals USG and CT scan evaluation of patients of acute and chronic pancreatitis- a cross-sectional, comparative study

2017 ◽  
Vol 5 (8) ◽  
pp. 3713 ◽  
Author(s):  
Aastha Bhatt ◽  
Awdhut Tiparse ◽  
Arpita Patel ◽  
Birwa Gandhi
Keyword(s):  
Ct Scan ◽  
Structural Changes ◽  
Radiation Hazard ◽  
Government Medical College ◽  
Detailed Characterization ◽  
Cross Sectional ◽  
Medical College ◽  
Adjacent Structures

Background: Pancreatitis is a condition of inflammation of pancreas with high rate of morbidity and mortality. USG provides the initial radiological assessment of the organ, clue of the extent of involvement and an opportunity to evaluate other abdominal organs. CT scan provides a cross-sectional anatomy of the organ, its internal structure, focal or diffuse involvement and involvement of adjacent structures. This study is done to evaluate the role of USG and CT scan in patients of pancreatitis admitted to Sir Takhtsinhji hospital, government medical college, Bhavnagar, Gujarat, India. Aim was to understand the role of CT and USG in determination of diagnosis of pancreatitis and to highlight and evaluate the cases in which USG failed to diagnose the cases which were helped through by CT.Methods: This study was done in department of radio diagnosis at Sir Takhtsinhji hospital, government medical college, Bhavnagar, Gujarat, India, over a period of one year from June 2015 to June 2016. Each patient was studied taking into consideration relevant clinical and laboratory factors. USG of patients was done using My Lab 40 or My Lab 20 plus machine. CT scan was done using GE 16 Slice CT scan machine.Results: Ultrasound by non-invasiveness, lack of radiation hazard and by ability to demonstrate structural changes in organ is first investigation of choice in pancreatitis. However, USG fails imaging in conditions with excess of bowel gas or fatty patient. It lacks in detailed characterization of the inflammatory process and does not delineate extent of necrosis of the gland. CT is superior to ultrasound for precise detection of size, parenchyma, MPD, calcification, pseudocyst, ascites, pleural effusion, necrosis and peri pancreatic region and hence helps to determine exact extent of inflammation of the organ, multi-system involvement and prognosis.Conclusions: Ultrasound by non-invasiveness, easy availability, cost parameters, lack of radiation hazard and by ability to demonstrate structural changes in organ is first investigation of choice in pancreatitis. However, ultrasonography lacks in detailed characterization of the extent of involvement of the organ and adjacent structures. CT is superior to ultrasound for precise detection and extension of the pancreatitis and it has better sensitivity and specificity than ultrasonography. 

Vascular and interstitial mechanics in canine pulmonary emphysema

1985 ◽  
Vol 59 (6) ◽  
pp. 1704-1715 ◽  
Author(s):  
S. N. Mink ◽  
H. W. Unruh ◽  
L. Oppenheimer
Keyword(s):  
Pulmonary Emphysema ◽  
Structural Changes ◽  
Lower Lobe ◽  
Fluid Exchange ◽  
Vascular Conductance ◽  
Edema Formation ◽  
Cross Sectional ◽  
Tissue Resistance ◽  
Wet Weight

We examined the changes in vascular and interstitial mechanics in pulmonary emphysema (PE) using a canine lobar model. PE was produced in the left lower lobe (LLL) of five dogs (group E) by six weekly intrabronchial instillations of the enzyme papain. In five control dogs (group C), a normal saline solution was used. In our in vivo preparation, vascular flow (Q) to the LLL was measured. Inflow (Ppa) and outlow (Pv) pressures to the LLL could be varied independently. The relationship of Ppa to Q was examined in zones 2 and 3 of West. The slope of the Ppa-Q relationship was used to determine vascular conductance, whereas the extrapolation to zero flow in zone 2 conditions represented the mean pressure required for vascular recruitment (Pi). Lobar weight gain was measured continuously. Following step increases in Ppa, the rapid increase in wet weight measured when Q to the LLL was zero was used to obtain vascular compliance (C). Subsequent slow increases in wet weight were used to determine the rate of fluid exchange with the interstitium (Qf). The slope of the Qf-Ppa relationship represented fluid conductance (Kf). The extrapolation to zero Qf gave the minimal pressure required for continuous edema formation (Pm). Compared with group C, vascular conductance (G) decreased and Pi increased in group E, whereas fluid conductance (Kf) and Pm increased. The decrease in G most likely resulted from the loss of vascular cross-sectional area in emphysematous lungs, whereas the increase in Pi was possibly due to mechanical changes in the lung interstitium which increased vessel closure. We propose that the increase in Kf in group E reflected an increase in interstitial conductance, such that due to structural changes in the interstitium in emphysematous lungs, tissue resistance to fluid flux decreased.

Surface Morphological Changes of Polyimide with Oxygen Reactive Ion Beam Etching (RIBE)

1988 ◽  
Vol 129 ◽  
Author(s):  
Kyung W. Paik ◽  
Arthur L. Ruoff
Keyword(s):  
Morphological Changes ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Ion Beam Etching ◽  
X Ray ◽  
Disordered Phase ◽  
Beam Incidence ◽  
Yield Difference ◽  
Sectional Plane

ABSTRACTAt the beginning of etching, surface asperities appeared on the top plane of the polyimide (PI) film. The formation of surface asperities is due to the ordered phase in PI film. The known dimension of the ordered phase measured by X-ray diffraction is consistant with the size of surface asperities, 100 Å, observed by TEM. Further ion doses made these asperties evolve into smooth bumps which then eroded into cones as a result of etch yield difference as a function of the angle of beam incidence Y(θ)/Y(0) which has a maximum at θ=70. Finally cones led to the development of grass-likestructure on the top plane of the PI film. The formation of platelike structure on the cross-sectional plane of PI indicates that the structural inhomogeniety of the PI film(the ordered and disordered phase) is the main cause for the surface morphological changes of PI.

Multi-Scale Overlapping Domain Decomposition to Consider Local Deformations in the Analysis of Thin-Walled Members

2014 ◽  
Vol 553 ◽  
pp. 667-672
Author(s):  
R. Emre Erkmen
Keyword(s):  
Numerical Technique ◽  
Global Analysis ◽  
Local Deformation ◽  
Local Analysis ◽  
Type Model ◽  
Cross Sectional ◽  
Multi Scale ◽  
Shell Type ◽  
Thin Walled ◽  
The Cross

Thin-walled members that have one dimension relatively large in comparison to the cross-sectional dimensions are usually modelled by using beam-column type finite element formulations. Beam-column elements however, are based on the assumption of rigid cross-section, thus they cannot consider the cross-sectional deformations such as local buckling and only allows considerations of the beam axis behaviour such as flexural or lateral-torsional buckling. Shell-type finite elements can be used to model the structure in order to consider these local deformation effects. Based on the Bridging multi-scale approach, this study proposes a numerical technique that is able to split the global analysis, which is performed by using simple beam-type elements, from the local analysis which is based on more sophisticated shell-type elements. As a result, the proposed multi-scale method allows the usage of shell elements in a local region to incorporate the local deformation effects on the overall behaviour of thin-walled members without necessitating a shell-type model for the whole member.

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