Shape Deformation Analysis Research Articles

Shape deformation analysis reveals the temporal dynamics of cell-type-specific homeostatic and pathogenic responses to mutant huntingtin

Loss of cellular homeostasis has been implicated in the etiology of several neurodegenerative diseases (NDs). However, the molecular mechanisms that underlie this loss remain poorly understood on a systems level in each case. Here, using a novel computational approach to integrate dimensional RNA-seq and in vivo neuron survival data, we map the temporal dynamics of homeostatic and pathogenic responses in four striatal cell types of Huntington's disease (HD) model mice. This map shows that most pathogenic responses are mitigated and most homeostatic responses are decreased over time, suggesting that neuronal death in HD is primarily driven by the loss of homeostatic responses. Moreover, different cell types may lose similar homeostatic processes, for example, endosome biogenesis and mitochondrial quality control in Drd1-expressing neurons and astrocytes. HD relevance is validated by human stem cell, genome-wide association study, and post-mortem brain data. These findings provide a new paradigm and framework for therapeutic discovery in HD and other NDs.

Numerical analysis of pattern shape deformation in UV imprint considering thermal deformation with UV shrinkage and curing

A novel numerical method for analyzing the deformation of molding patterns on UV imprint with soft molds considering thermal deformation in addition to UV shrinkage and curing is presented. In the case of UV imprint using an easily deformable mold-like PDMS, transfer error on UV resin is caused by thermal expansion/contraction arising from UV reaction heat and by UV shrinkage. Specifically, when a UV resin with high reaction heat such as cation polymerization-type UV resin is used, thermal deformation has a nonnegligible effect on pattern shape deformation. Therefore, it is necessary to consider thermal deformation caused by UV reaction heat in the numerical deformation analysis of UV imprint requiring high surface accuracy, such as optical devices. The present method newly adopts the theory of reaction rate to consider the temperature-dependent UV reaction rate and introduces an advanced idea of virtual temperature as a measure of UV reaction progress. By defining the time histories of thermal deformation and UV shrinkage as a function of virtual temperature, the effects of both are considered simultaneously. In order to apply the present method to actual imprints, temperature measurement experiments and various rheometry experiments are conducted on a target UV resin to identify its model parameters. A validation analysis of the present method is performed on an actual micromirror array imprint and shows that the simulation accuracy of transfer error can be significantly improved by considering thermal deformation.

Numerical Analysis of Pattern Shape Deformation in UV Imprint Due to Curing Shrinkage

Numerical Analysis of Pattern Shape Deformation in UV Imprint Due to Curing Shrinkage

Analysis of Shape Deformation from Densification of Additive Manufacturing Parts in Selective Laser Sintering

Additive Manufacturing (AM) has recently attracted huge attentions as a technology for the next generation of industry. Particularly for the manufacturing purposes, various aspects of AM are being studied and applied, such as prototypes for assembly tests, jig production, and actual parts manufacturing. Selective Laser Sintering (SLS) using polyamide is easy to apply to various industries, such as its superior mechanical properties and higher design freedom, but design that takes into account variation in dimensions after manufacture often leads to costly and time-consuming problems. As a way to reduce deformation in the production process, previous studies approached experimentally about the effects of thermal deformation or residual stress on deformation. This is difficult to apply to a specimen of various shapes and sizes and also has limitations as a common solution to dimensional inaccuracies. To propose a solution for mitigating shape deformation of AM part, this paper focused on the effect of phase change of material among various processing parameters that cause shape deformation and tries to present an analytic model. Modeling on the melting and sintering phenomena of powder was presented using Euler-Bernui beam equation. The proposed model was verified by measuring the density variation of manufactured AM components and analyzing the correlation between the degree of contraction and the energy density. Factors such as layer thickness, part thickness, and part placement height were identified to have significant effects on the actual deformation. It is also confirmed that dimensional accuracy of parts that show large deformation by bending has increased by 64.2% when a calibration model is applied through manufacturing of actual parts. Time and cost can be saved for industrial application of AM by applying this proposed calibration model. In addition, by using this model more efficiently in the CAD design process, dimensional accuracy can be enhanced.

Analysis of Shape and Dimensional Deformation of the Gear Made by Digital Light Processing (DLP) Additive Technology and Measured by Industrial Tomography

Industrial tomography is currently the fastest growing sector of non-destructive research. Until recently, the use of computed tomography in industry has been limited mostly to defects in materials due to lack of accuracy. Modern measuring machines combining metrology and tomography can extract information about the external geometry and volume of the part with high precision from a single scan. This article deals with the transmission gearing scanning, which is a functional component used in the mechanical transmission design. It is imperative that it does not contain internal defects that can largely render the transmission ineffective due to the strain caused by stress. The component is produced by Digital Light Processing (DLP) additive technology. The chosen production method ensures greater strength of the part. The part will be made of material call as „Proto GRY “on a FabPro1000 printer from the company 3D Systems, Inc. The production process of the model will depend on the change in the orientation of the part.

Analysis of Shape and Dimensional Deformation of the Model with a Precision Circular Hole Produced by Digital Light Processing (DLP) Additive Technology

The article is about manufacturing a component with a precision circular hole by Digital Light Processing (DLP) additive technology for inserting another part. The accuracy of the hole itself depends on the choice of production technology and the appropriate material. Deformation of the inner wall of the hole prevents correct insertion of the part - nut of trapezoidal threaded rod. This article analyzes the feasibility of manufacturing a component using Digital Light Processing (DLP) additive technology and the use of liquid resin „Proto GRY“ for the manufacture a component. Among additive technologies processes, digital light processing (DLP) is typically seen as the technology capable of reaching the highest standards in terms of part complexity and precision. DLP technology rely on the use of light, typically in the UV region of the spectrum (380 – 405 nm), to cure a photosensitive viscous resin. This resin, typically composed of epoxy or acrylic and methacrylic monomers, will polymerize and harden when exposed to light. As light shines on the vat to create specific shapes or patterns that compose each layer, a solid object can be formed and extracted from the otherwise liquid resin.

Shape deformation analysis of anode-supported solid oxide fuel cell by electro-chemo-mechanical simulation

In this study, the analysis of a solid oxide fuel cell (SOFC) is conducted, starting at a high temperature under the assumption of a stress-free during cell sintering at that temperature level. The deformation during the temperature decrease after sintering is reflected not only in the initial shape of the cell at a low temperature, but also in the deformation behavior during operation. The time variation of the cell shape is clarified in terms of thermal, chemical, and creep strains. In these simulations, we use our previously developed analysis method for electrochemical and mechanical coupling phenomena by incorporating general-purpose finite element analysis software and its pre-/post-processing functions.

Chronic exposure to haloperidol and olanzapine leads to common and divergent shape changes in the rat hippocampus in the absence of grey-matter volume loss.

One of the most consistently reported brain abnormalities in schizophrenia (SCZ) is decreased volume and shape deformation of the hippocampus. However, the potential contribution of chronic antipsychotic medication exposure to these phenomena remains unclear. We examined the effect of chronic exposure (8 weeks) to clinically relevant doses of either haloperidol (HAL) or olanzapine (OLZ) on adult rat hippocampal volume and shape using ex vivo structural MRI with the brain retained inside the cranium to prevent distortions due to dissection, followed by tensor-based morphometry (TBM) and elastic surface-based shape deformation analysis. The volume of the hippocampus was also measured post-mortem from brain tissue sections in each group. Chronic exposure to either HAL or OLZ had no effect on the volume of the hippocampus, even at exploratory thresholds, which was confirmed post-mortem. In contrast, shape deformation analysis revealed that chronic HAL and OLZ exposure lead to both common and divergent shape deformations (q = 0.05, FDR-corrected) in the rat hippocampus. In particular, in the dorsal hippocampus, HAL exposure led to inward shape deformation, whereas OLZ exposure led to outward shape deformation. Interestingly, outward shape deformations that were common to both drugs occurred in the ventral hippocampus. These effects remained significant after controlling for hippocampal volume suggesting true shape changes. Chronic exposure to either HAL or OLZ leads to both common and divergent effects on rat hippocampal shape in the absence of volume change. The implications of these findings for the clinic are discussed.

Principal component analysis of the shape deformations of the hippocampus in Alzheimer's disease.

In this paper, we present the principal component analysis (PCA) of shape deformations of bilateral hippocampi in Alzheimer's disease (AD) as derived in the large deformation diffeomorphic metric mapping setting. We investigated the PCA patterns (the scores and loadings) of the bilateral hippocampi for 51 subjects, 28 of which had AD while 23 were normal aging. Student's t-tests were used to select the components displaying significant group difference for a more purposed analysis. Our findings revealed that the head part of the hippocampus in each hemisphere, to be specific the CA1 and subiculum subregions, contributed the most to the significant group differences. To further our analysis, we examined the classification accuracy yielded by these shape deformation patterns when either solely PCA or PCA followed by a Student's t-test was utilized as the approach to dimension reduction. Linear discriminant analysis (LDA) and support vector machine (SVM) were used as candidates for the classification technique. According to our leave-one-out cross-validation experiments, SVM had a much higher accuracy than LDA, with the best performance (overall accuracy: 94.1% (48/51); sensitivity: 92.9% (26/28); and specificity: 95.7% (22/23)) achieved by SVM when using both the left and the right hippocampal shape deformation patterns and employing solely PCA for dimension reduction.

Shape deformation analysis from the optimal control viewpoint

A crucial problem in shape deformation analysis is to determine a deformation of a given shape into another one, which is optimal for a certain cost. It has a number of applications in particular in medical imaging.In this article we provide a new general approach to shape deformation analysis, within the framework of optimal control theory, in which a deformation is represented as the flow of diffeomorphisms generated by time-dependent vector fields. Using reproducing kernel Hilbert spaces of vector fields, the general shape deformation analysis problem is specified as an infinite-dimensional optimal control problem with state and control constraints. In this problem, the states are diffeomorphisms and the controls are vector fields, both of them being subject to some constraints. The functional to be minimized is the sum of a first term defined as geometric norm of the control (kinetic energy of the deformation) and of a data-attachment term providing a geometric distance to the target shape.This point of view has several advantages. First, it allows one to model general constrained shape analysis problems, which opens new issues in this field. Second, using an extension of the Pontryagin maximum principle, one can characterize the optimal solutions of the shape deformation problem in a very general way as the solutions of constrained geodesic equations. Finally, recasting general algorithms of optimal control into shape analysis yields new efficient numerical methods in shape deformation analysis. Overall, the optimal control point of view unifies and generalizes different theoretical and numerical approaches to shape deformation problems, and also allows us to design new approaches.The optimal control problems that result from this construction are infinite dimensional and involve some constraints, and thus are nonstandard. In this article we also provide a rigorous and complete analysis of the infinite-dimensional shape space problem with constraints and of its finite-dimensional approximations.

Multi-vector composition and its application in landscape patch shape deformation and dynamic analysis

The quantitative expression and monitoring of patch shape deformation is an important content of landscape ecology. In this paper, a new multi-vector method is put forward based on curve representation in differential geometry, which is the composition of Centroid Displacement Vector (CDV), Local Deformation Vector (LDV) and the unit normal vector on the patch boundary. These composition vectors (CVs) not only add a new direction dimension to the landscape pattern metrics already available, but also provide multi-scale information, i.e. CV at every point and the boundary segment CV (BSCV). This new information can provide a quantification basis for a deeper understanding of the mechanisms of shape deformation and dynamic analysis. An application of CVs to patch dynamics in the Yancheng National Nature Reserve (YNNR) in China is given to validate the methodology. The susceptibility to invasion of the Common Seepweed in the core area of YNNR is evaluated quantitatively by CVs method. Our results indicate that the rate of invasion of Smooth Cord-grass into Common Seepweed patch has increased by 1.5 times from 1995 to 2002. This is considered to be the dominant factor causing Common Seepweed patches to shrink and change dynamically. These results help us better understand the landscape patch shape deformation and analyze the driver forces of landscape change, and they also provide the quantitative basis for the effective protection of the nature reserve area.

Spatially localized hippocampal shape analysis in late‐life cognitive decline

We present a method for generating data-driven, concise, and spatially localized parameterizations of hippocampal (HP) shape, and use the method to analyze HP atrophy in late-life cognitive decline. The method optimizes a set of shape basis vectors (shape components) that strike a balance between spatial locality and compact representation of population shape characteristics. The method can be used for exploratory analysis of localized shape deformations in any population of HP on which point-to-point correspondence mappings have been established via anatomical landmarking or high-dimensional warping. Experiments combine the method with an automated HP to HP mapping method to analyze tracings of 101 elderly subjects with normal cognition, mild cognitive impairment, and Alzheimer's Disease (AD) from an AD Center population. Results suggest that shape components corresponding to atrophy to the CA1 and subiculum HP fields--where early AD pathology is located--correlate strongly with robust measures of the cognitive dysfunction that is typical of early AD. Furthermore, the energy function minimized by the shape component optimization technique is shown to be smooth with few local minima, suggesting that the method may be relatively easy to apply in practice.

Thalamus surface shape deformity in obsessive-compulsive disorder and schizophrenia

The authors performed a three-dimensional shape deformation analysis to clarify the various patterns of specific thalamic nuclei abnormality using three age-matched and sex-matched groups of 22 patients with obsessive-compulsive disorder (OCD), 22 patients with schizophrenia and 22 control participants. Compared with the healthy volunteers, the anterior, lateral outward surface deformities of the thalamus were significant in OCD patients, whereas the posterior, medial outward deformities of the thalamus were prominent in schizophrenia patients. In terms of thalamic asymmetry, both OCD and schizophrenia patients exhibited the loss of a leftward pattern of asymmetry on the posterior, medial surface of the thalamus. Different patterns of shape abnormality of specific thalamic nuclei may be related to the different phenomenology of OCD and schizophrenia.

A general approach to shape characterisation for biomedical problems

In this paper, we present a general approach to shape characterisation and deformation analysis of 2D/3D deformable visual objects. In particular, we define a reference dynamic model, encoding morphological and functional properties of an objects class, capable of analysing different scenarios in heart left ventricle analysis. The proposed approach is suitable for generalisation to the analysis of periodically deforming anatomical structures, where it could provide useful support in medical diagnosis. Preliminary results in heart left ventricle analysis are discussed.

Shape deformity of the corpus striatum in obsessive–compulsive disorder

Volumetric changes of striatal structures based on magnetic resonance imaging (MRI) have been inconsistent in patients with obsessive–compulsive disorder (OCD) due to methodological limitations. The purpose of this study was to investigate shape deformities of the corpus striatum in patients with OCD. We performed 3-D shape deformation analysis of the caudate nucleus, the putamen, and the globus pallidus in 36 patients with OCD and 36 healthy normal subjects. Shape analysis showed deformity of the striatal structures, especially the caudate nucleus. Outward deformities in the superior, anterior portion of the bilateral caudate were observed in patients with OCD. In addition, an outward deformity in the inferior, lateral portion of the left putamen was also detected. These results suggest that patients with OCD have shape deformities of the corpus striatum, especially the caudate nucleus, compared with healthy normal subjects, and that shape analysis may provide an important complement to volumetric MRI studies in investigating the pathophysiology of OCD.

Kernel Fisher discriminant for shape-based classification in epilepsy

In this paper, we present the application of kernel Fisher discriminant in the statistical analysis of shape deformations that indicate the hemispheric location of an epileptic focus. The scans of two classes of patients with epilepsy, those with a right and those with a left anterior medial temporal lobe focus (RATL and LATL), as validated by clinical consensus and subsequent surgery, were compared to a set of age and sex matched healthy volunteers using both volume and shape based features. Shape-based features are derived from the displacement field characterizing the non-rigid deformation between the left and right hippocampi of a control or a patient as the case may be. Using the shape-based features, the results show a significant improvement in distinguishing between the controls and the rest (RATL and LATL) vis-a-vis volume-based features. Using a novel feature, namely, the normalized histogram of the 3D displacement field, we also achieved significant improvement over the volume-based feature in classifying the patients as belonging to either of the two classes LATL or RATL, respectively. It should be noted that automated identification of hemispherical foci of epilepsy has not been previously reported.

A Simplified Structural Model for the Analysis of Shape Deformations of the LHC Superconducting Dipole Cold Mass

In superconducting magnets for particle accelerators the mechanical accuracy along the length of the Cold Mass is one of the crucial parameters to guarantee the field quality needed by beam dynamics. This issue is made even more challenging in the twin-aperture LHC superconducting dipole where tolerances in the 0.3-1 mm range shall be obtained over a length of 15 m, for a Cold Mass of about 30 t which, to minimize thermal losses, is supported in three points only. To reach this goal a number of geometrical checks and analyses are carried out at all stages of magnet assembly, handling, installation and operation. In this paper we present the structural model of the dipole based on which the checks and the analysis are performed, the nature of the geometrical imperfections identified and the temporary or permanent shape modifications predicted

Deformable model with surface registration for hippocampal shape deformity analysis in schizophrenia

Changes to the hippocampal structure have been reported as consistent structural abnormalities in schizophrenic patients and have been related to the learning and memory deficits in such patients. Although many magnetic resonance (MR) imaging studies have focused on the hippocampal volume, local structural changes were difficult to discriminate from normal neuroanatomical variations. 3D shape deformation analysis of the brain structure may reflect localized schizophrenic abnormalities. A deformable model, evolved from the ellipsoid to hippocampal surface, with 2562 vertexes, was developed to analyze the left and right hippocampus shapes in 22 schizophrenic patients and 22 healthy age and gender matched controls. One of the most critical issues in the shape analysis is the determination of homologous points between two objects. To determine more accurate corresponding points, an alignment procedure, consisting of coarse and fine steps, following a deformation process, was applied. The performance of the alignment process was tested using artificial data, to get the alignment error to within 3° for each angle. A volume analysis indicated the hippocampal volume to be bilaterally reduced in schizophrenic patients compared to the normal controls, with a shape analysis showing a deformity pattern of the hippocampal surface. Bilateral inward deformities in the anterior and posterior hippocampus and a unilateral outward deformity in the right anterior hippocampus were observed, respectively.

Deformable model with surface registration for hippocampal shape deformity analysis in schizophrenia

Changes to the hippocampal structure have been reported as consistent structural abnormalities in schizophrenic patients and have been related to the learning and memory deficits in such patients. Although many magnetic resonance (MR) imaging studies have focused on the hippocampal volume, local structural changes were difficult to discriminate from normal neuroanatomical variations. 3D shape deformation analysis of the brain structure may reflect localized schizophrenic abnormalities. A deformable model, evolved from the ellipsoid to hippocampal surface, with 2562 vertexes, was developed to analyze the left and right hippocampus shapes in 22 schizophrenic patients and 22 healthy age and gender matched controls. One of the most critical issues in the shape analysis is the determination of homologous points between two objects. To determine more accurate corresponding points, an alignment procedure, consisting of coarse and fine steps, following a deformation process, was applied. The performance of the alignment process was tested using artificial data, to get the alignment error to within 3° for each angle. A volume analysis indicated the hippocampal volume to be bilaterally reduced in schizophrenic patients compared to the normal controls, with a shape analysis showing a deformity pattern of the hippocampal surface. Bilateral inward deformities in the anterior and posterior hippocampus and a unilateral outward deformity in the right anterior hippocampus were observed, respectively.

Three Dimensional Analysis of Shape Deformation in Injection Molded Optical Lens

Abstract The shape deformation of optical pickup lens in injection molding was investigated in this study. It was realized that residual stresses and warpage deformation in injection molding parts were affected by different process conditions such as melt temperature, mold temperature, packing pressure and time. A two dimensional analysis in injection molding only provides information on the thickness shrinkage for optical lens. In order to simulate the surface contour variations, a three-dimensional warpage analysis was conducted in this study using the finite element method. Moldings under different packing pressures and mold temperatures were numerically investigated to study the effects on the residual stresses and deformation of a molded pickup lens. The packing pressure and mold temperature were found to be the dominant factors that affect the shrinkage of lens in the thickness direction, resulting in surface contour deviation.