Papers by Gabriela Sanchez Castro
ISO standard on wood veneers
Sherwood Foreste Ed Alberi Oggi, 2009
Multimedia Content Delivery System
International Journal of Material Forming, 2010
Micromoulding is a technology capable of mass producing components with micro and nano scale surf... more Micromoulding is a technology capable of mass producing components with micro and nano scale surface features. The production process can be sensitive to a number of variables that can modify the complex threedimensional surface geometry of the components. The surface is often a crucial determinant of the product's functionality and therefore must be subject to strict quality control. Surface measurement techniques such as White Light Interferometry (WLI) generate data in the form of Cartesian point clouds, which are generally large and somewhat unmanageable. Thus, new methods for characterizing efficiently the surfaces associated with these data sets will result in better controlled product quality. Here, we propose a surface characterization technique based on the use of Partial Differential Equations (PDEs). This method characterizes the outer surface contours obtained from raw measurement data. The aim of this technique is to identify parameters providing a good description of the surface profile of a micromoulded product. The measured set of parameters is compared against the theoretical values associated with an ideal surface profile, usually that of the mould cavity, potentially providing a means of quality assessment.
Journal of Food Research, 2015
This study evaluated the effect of baru (Dipteryx alata Vog.) almond, an edible seed native from ... more This study evaluated the effect of baru (Dipteryx alata Vog.) almond, an edible seed native from Brazilian Savanna, and Brazil nut (Bertholletia excelsa H. B. K.) on serum lipid profile and hepatic lipid peroxidation in rats fed high-fat diets. Four groups of eight young adult male Wistar rats were treated for nine weeks with one of the following diets: high-fat diets - 0.1% colic acid + 1% cholesterol + 5% lard + 15% of lipid from lard, baru almond or Brazil nut - and reference diet (7% soybean oil). Groups fed with baru almond and Brazil nut showed lower serum contents of total cholesterol and triacylglycerols than those of lard group. Baru almond group also showed higher HDL-c concentration than those of Brazil nut and lard groups, similar to that of reference group. Lipid peroxidation (through total malondialdehyde) was lower and vitamin E content was higher in the livers of the animals treated with baru almond and Brazil nut than those of lard group. These results indicate that...
Lecture Notes in Computer Science, 2011
In this work we propose a talking head system for animating facial expressions using a template f... more In this work we propose a talking head system for animating facial expressions using a template face generated from Partial Differential Equations (PDEs). It uses a set of preconfigured curves to calculate an internal template surface face. This surface is then used to associate various facial features with a given 3D face object. Motion retargeting is then used to transfer the deformations in these areas from the template to the target object. The procedure is continued until all the expressions in the database are calculated and transferred to the target 3D human face object. Additionally the system interacts with the user using an artificial intelligence (AI) chatterbot to generate response from a given text. Speech and facial animation are synchronized using the Microsoft Speech API, where the response from the AI bot is converted to speech.
Reconstructing Multiresolution Mesh for Web Visualization Based on PDE Resampling
Lecture Notes in Computer Science, 2011
Various Partial Differential Equations (PDEs) have been used in computer graphics for approximati... more Various Partial Differential Equations (PDEs) have been used in computer graphics for approximating surfaces of geometric shapes by finding solutions to PDEs, subject to suitable boundary conditions. The PDE boundary conditions are defined as 3D curves on surfaces of the shapes. We propose how to automatically derive these curves from the surface of the original polygon mesh. Analytic solutions to
Lecture Notes in Computer Science, 2008
Direct parameterisation is among the most widely used facial animation techniques but requires co... more Direct parameterisation is among the most widely used facial animation techniques but requires complicated ways to animate face models which have complex topology. This paper develops a simple solution by introducing a PDE-based facial animation scheme. Using a PDE face model means we only needs to animate a group of boundary curves without using any other conventional surface interpolation algorithms. We describe the basis of the method and show results from a practical implementation.
Parameterisation of facial expressions on PDE sur- face representations of human faces are presen... more Parameterisation of facial expressions on PDE sur- face representations of human faces are presented in this work. Taking advantage of the boundary-value approach inherent to Bloor-Wilson PDE method, facial expressions are achieved by manipulating the original boundary curves. Such curves are responsible for generating a surface rep- resentation of a human face in its neutral configuration, so that regions on
Acta Cirurgica Brasileira, 2011
PURPOSE: The increase in fructose consumption is paralleled by a higher incidence of obesity worl... more PURPOSE: The increase in fructose consumption is paralleled by a higher incidence of obesity worldwide. This monosaccharide is linked to metabolic syndrome, being associated with hypertriglyceridemia, hypertension, insulin resistance and diabetes mellitus. It is metabolized principally in the liver, where it can be converted into fatty acids, which are stored in the form of triglycerides leading to NAFLD. Several models of NAFLD use diets high in simple carbohydrates. Thus, this study aimed to describe the major metabolic changes caused by excessive consumption of fructose in humans and animals and to present liver abnormalities resulting from high intakes of fructose in different periods of consumption and experimental designs in Wistar rats. METHODS: Two groups of rats were fasted for 48 hours and reefed for 24 or 48 hours with a diet containing 63% fructose. Another group of rats was fed an diet with 63% fructose for 90 days. RESULTS: Refeeding for 24 hours caused accumulation of...
Medicina (Ribeirao Preto. Online), 2009
Modelo de estudo: Estudo experimental. Objetivos: este estudo teve como objetivo avaliar e cara... more Modelo de estudo: Estudo experimental. Objetivos: este estudo teve como objetivo avaliar e caracterizar a dieta hipoprotéica como um modelo experimental para estudo de EHNA. Métodos: foram utilizados ratos da linhagem Wistar divididos em dois grupos com dietas isocalóricas: controle (GC) no qual a dieta utilizada seguiu o preconizado pela AIN-93 e hipoprotéico (GH) com quantidade de proteína reduzida de 20% para 10%. As dietas e água foram ofertadas ad libitum por quatro semanas. Após esse período, os animais foram sacrificados e analisados: glicemia; nitrogênio urinário; proteína sérica; gordura hepática; colesterol; variação de peso e quantidade de ração consumida. Resultados: glicemia e nitrogênio urinário não apresentaram diferenças significativas entre GC e GH (p>0,05), a variação de peso no último dia do experimento foi significativa (p<0,02). A porcentagem de gordura hepática foi estatisticamente maior no GH, quando comparado ao GC (p<0,04). Foram menores o nível d...
Automatic Reconstruction and Web Visualization of Complex PDE Shapes
2010 International Conference on Cyberworlds, 2010
Page 1. Automatic Reconstruction and Web Visualization of Complex PDE Shapes Ming-Yong Pang, Yun ... more Page 1. Automatic Reconstruction and Web Visualization of Complex PDE Shapes Ming-Yong Pang, Yun Sheng, Alexei Sourin Gabriela González Castro, Hassan Ugail School of Computer Engineering Centre for Visual Computing, Nanyang Technological University ...
On the Development of an Interactive Talking Head System
2010 International Conference on Cyberworlds, 2010
Page 1. On the development of an interactive talking head system Michael Athanasopoulos, Hassan U... more Page 1. On the development of an interactive talking head system Michael Athanasopoulos, Hassan Ugail and Gabriela González Castro School of Computing, Informatics and Media, University of Bradford, Bradford BD7 1DP ...
Cyclic Animation of Human Body Using PDE Surfaces and Maya
2009 International Conference on CyberWorlds, 2009
Page 1. Cyclic Animation of Human Body Using PDE Surfaces and Maya Michael Athanasopoulos, Gabrie... more Page 1. Cyclic Animation of Human Body Using PDE Surfaces and Maya Michael Athanasopoulos, Gabriela González Castro and Hassan Ugail School of Informatics, University of Bradford, Bradford BD7 1DP mathana1, g.gonzalezcastro1, [email protected] ...
2009 International Conference on CyberWorlds, 2009
We propose an efficient alternative to commonly used parametric surfaces such as NURBS surfaces f... more We propose an efficient alternative to commonly used parametric surfaces such as NURBS surfaces for definition of complex geometry in shared virtual spaces. Our mathematical model allows to define objects by only providing coordinates of the section curves in 3-space. The resulting parametric functions allow fast calculation of the coordinates of the points on the surface of the objects. We devise an algorithm which evaluates the coefficients of these functions in real time. Given the small size of the resulting formulas and interactive rates for their calculation, we are able to efficiently use such PDE-based models for making virtual objects in shared virtual spaces. We describe the modeling framework and illustrate the proposed theoretical concepts with our function-based extension of VRML and X3D.
International Journal of Pharmaceutics, 2012
This work presents a technique for shape modelling of cylindrical and spherical tablets subject t... more This work presents a technique for shape modelling of cylindrical and spherical tablets subject to compression. This technique is based on the use of partial differential equations (PDEs), the biharmonic equation in particular. The deformation of the compressed elastic-plastic tablet of both shapes was obtained using the existing contact models found in literature. The mathematical properties of the biharmonic equation have been exploited to achieve simple mathematical expressions characterising the shape of the distorted tablet. Thus, the height, radius and contact area of both configurations due to uniaxial compression are represented by analytic expressions relating the coefficients associated with the solution of the biharmonic equation. The results obtained from the PDE-based simulation are compared with the theoretical ones. It is found that the analytic solution of the elliptic PDE can be utilised to represent the physical changes of the deformed object.
International Journal of Pharmaceutics, 2011
The mechanisms involved for compaction of pharmaceutical powders have become a crucial step in th... more The mechanisms involved for compaction of pharmaceutical powders have become a crucial step in the development cycle for robust tablet design with required properties. Compressibility of pharmaceutical materials is measured by a force-displacement relationship which is commonly analysed using a well known method, the Heckel model. This model requires the true density and compacted powder mass value to determine the powder mean yield pressure. In this paper, we present a technique for shape modelling of pharmaceutical tablets based on the use of partial differential equations (PDEs). This work also presents an extended formulation of the PDE method to a higher dimensional space by increasing the number of parameters responsible for describing the surface in order to generate a solid tablet. Furthermore, the volume and the surface area of the parametric cylindrical tablet have been estimated numerically. Finally, the solution of the axisymmetric boundary value problem for a finite cylinder subject to a uniform axial load has been utilised in order to model the displacement components of a compressed PDE-based representation of a tablet. The Heckel plot obtained from the developed model shows that the model is capable of predicting the compaction behaviour of pharmaceutical materials since it fits the experimental data accurately.
The Visual Computer, 2007
Computer aided geometric design is an area where the improvement of surface generation techniques... more Computer aided geometric design is an area where the improvement of surface generation techniques is an everlasting demand since faster and more accurate geometric models are required. Traditional methods for generating surfaces were initially mainly based upon interpolation algorithms. Recently, partial differential equations (PDE) were introduced as a valuable tool for geometric modelling since they offer a number of features from which these areas can benefit. This work summarises the uses given to PDE surfaces as a surface generation technique together with some other applications to computer graphics.
The Visual Computer, 2010
Three-dimensional (3D) representations of complex geometric shapes, especially when they are reco... more Three-dimensional (3D) representations of complex geometric shapes, especially when they are reconstructed from magnetic resonance imaging (MRI) and computed tomography (CT) data, often result in large polygon meshes which require substantial storage for their handling, and normally have only one fixed level of detail (LOD). This can often be an obstacle for efficient data exchange and interactive work with such objects. We propose to replace such large polygon meshes with a relatively small set of coefficients of the patchwise partial differential equation (PDE) function representation. With this model, the approximations of the original shapes can be rendered with any desired resolution at interactive rates. Our approach can directly work with any common 3D reconstruction pipeline, which we demonstrate by applying it to a large reconstructed medical data set with irregular geometry.
The Visual Computer, 2010
This work presents an efficient and fast method for achieving cyclic animation using Partial Diff... more This work presents an efficient and fast method for achieving cyclic animation using Partial Differential Equations (PDEs). The boundary-value nature associated with elliptic PDEs offers a fast analytic solution technique for setting up a framework for this type of animation. The surface of a given character is thus created from a set of predetermined curves, which are used as boundary conditions so that a number of PDEs can be solved. Two different approaches to cyclic animation are presented here. The first consists of using attaching the set of curves to a skeletal system holding the animation for cyclic motions linked to a set mathematical expressions, the second one exploits the spine associated with the analytic solution of the PDE as a driving mechanism to achieve cyclic animation, which is also manipulated mathematically. The first of these approaches is implemented within a framework related to cyclic motions inherent to human-like characters, whereas the spine-based approach is focused on modelling the undulatory movement observed in fish when swimming. The proposed method is fast and accurate. Additionally, the animation can be either used in the PDE-based surface representation of the model or transferred to the original mesh model by means of a point to point map. Thus, the user is offered with the choice of using either of these two animation representations of the same object, the selection depends on the computing resources such as storage and memory capacity associated with each particular application.
The Journal of Nutrition, 2013
Dietary choline is required for proper structure and dynamics of cell membranes, lipoprotein synt... more Dietary choline is required for proper structure and dynamics of cell membranes, lipoprotein synthesis, and methyl-group metabolism. In mammals, choline is synthesized via phosphatidylethanolamine N-methyltransferase (Pemt), which converts phosphatidylethanolamine to phosphatidylcholine. Pemt 2/2 mice have impaired VLDL secretion and developed fatty liver when fed a high-fat (HF) diet. Because of the reduction in plasma lipids, Pemt 2/2 /low-density lipoprotein receptor knockout (Ldlr 2/2) mice are protected from atherosclerosis. The goal of this study was to investigate the importance of dietary choline in the metabolic phenotype of Pemt 2/2 /Ldlr 2/2 male mice. At 10-12 wk of age, Pemt +/+ /Ldlr 2/2 (HF +/+) and half of the Pemt 2/2 /Ldlr 2/2 (HF 2/2) mice were fed an HF diet with normal (1.3 g/kg) choline. The remaining Pemt 2/2 /Ldlr 2/2 mice were fed an HF diet supplemented (5 g/kg) with choline (HFCS 2/2 mice). The HF diet contained 60% of calories from fat and 1% cholesterol, and the mice were fed for 16 d. HF 2/2 mice lost weight and developed hepatomegaly, steatohepatitis, and liver damage. Hepatic concentrations of free cholesterol, cholesterol-esters, and triglyceride (TG) were elevated by 30%, 1.1-fold and 3.1-fold, respectively, in HF 2/2 compared with HF +/+ mice. Choline supplementation normalized hepatic cholesterol, but not TG, and dramatically improved liver function. The expression of genes involved in cholesterol transport and esterification increased by 50% to 5.6-fold in HF 2/2 mice when compared with HF +/+ mice. Markers of macrophages, oxidative stress, and fibrosis were elevated in the HF 2/2 mice. Choline supplementation normalized the expression of these genes. In conclusion, HF 2/2 mice develop liver failure associated with altered cholesterol metabolism when fed an HF/normal choline diet. Choline supplementation normalized cholesterol metabolism, which was sufficient to prevent nonalcoholic steatohepatitis development and improve liver function. Our data suggest that choline can promote liver health by maintaining cholesterol homeostasis.
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Papers by Gabriela Sanchez Castro