Search results for "REPRESENTATION"

The solvent-excluding surface as a descriptor of ionic channels: Gramicidin-A

1998

Abstract We have set out a methodology for checking the performance of the methods used to compute the Solvent-Excluding Surface. The method consists of computing the area of the Solvent-Excluding Surface of a model of channel, with a fixed pore size, for several values of the solvent radius. The graphical representation of the value of the area versus the radius of the solvent sphere shows a sharp change just at the radius of the pore. With this model we may analyze the ability of each method to describe small changes of the surface. We made the study with GEPOL93, older versions of GEPOL and MSDOT. The study is applied to a natural protein channel, as is Gramicidin-A, showing that this ty…

GEPOL: An improved description of molecular surfaces II. Computing the molecular area and volume

1991

The algorithm used by the program GEPOL for a finer description of molecular surface (for a fast calculation of molecular area and volume and for an efficient selection of sampling points) is presented in detail. Different types of surfaces such as van der Waals and Richard's molecular surfaces can be computed. As we described in the first article (J.L. Pascual-Ahuir and E. Silla, J. Comp. Chem., 11, 1047(1990)), GEPOL begins by building a set of spherical surfaces which fill the space which is not solvent accessible. In this second article, a triangular tessellation approach to select the parts of these spherical surfaces which form the molecular surface is described. By using a data coded…

From A Medial Surface To A Mesh

2012

Medial surfaces are well-known and interesting surface skeletons. As such, they can describe the topology and the geometry of a 3D closed object. The link between an object and its medial surface is also intuitively understood by people. We want to exploit such skeletons to use them in applications like shape creation and shape deformation. For this purpose, we need to define medial surfaces as Shape Representation Models (SRMs). One of the very first task of a SRM is to offer a visualization of the shape it describes. However, achieving this with a medial surface remains a challenging problem. In this paper, we propose a method to build a mesh that approximates an object only described by …

INITIAL PARAMETRIC REPRESENTATION OF BLOBS

2009

Blobs, developed by J.F. Blinn in 1982, are the implicit surfaces obtained by composition of a real numerical function and a distance function. Since, many authors (C. Murakami, H. Nishimura, G. Wyvill…) defined their own function of density, from these implicit surfaces are interesting from several points of view. In particular, their fusion makes it possible to easily obtain an implicit equation of resulting surface. However, these surfaces do not admit a parametric equation yet. In this article, we will establish the parametric equation of two blobs in fusion, defined by the function of density of C. Murakami, by using an algebraic method. Then, we will develop another method, based on …

Biologically Inspired Model for Inference of 3D Shape from Texture.

2015

A biologically inspired model architecture for inferring 3D shape from texture is proposed. The model is hierarchically organized into modules roughly corresponding to visual cortical areas in the ventral stream. Initial orientation selective filtering decomposes the input into low-level orientation and spatial frequency representations. Grouping of spatially anisotropic orientation responses builds sketch-like representations of surface shape. Gradients in orientation fields and subsequent integration infers local surface geometry and globally consistent 3D depth. From the distributions in orientation responses summed in frequency, an estimate of the tilt and slant of the local surface can…

Boolean operations with implicit and parametric representation of primitives using R-functions

2005

We present a new and efficient algorithm to accurately polygonize an implicit surface generated by multiple Boolean operations with globally deformed primitives. Our algorithm is special in the sense that it can be applied to objects with both an implicit and a parametric representation, such as superquadrics, supershapes, and Dupin cyclides. The input is a constructive solid geometry tree (CSG tree) that contains the Boolean operations, the parameters of the primitives, and the global deformations. At each node of the CSG tree, the implicit formulations of the subtrees are used to quickly determine the parts to be transmitted to the parent node, while the primitives' parametric definition …

Mamluk Reproductions: Survey and Analysis of Tombs in the Cemetery of Sant’Orsola in Palermo.

2016

The contribution presents a study of various funeral chapels found in the cemetery of Sant'Orsola in Palermo. Realised during the 19th and 20th centuries, they van be taken as examples of Sicilian Orientalism. An original reading of the Rutelli Chapel, starting from the unpublished survey of its current state, provides an understanding of its geometry and morphology. The survey was conducted using the techniques of Structure from Motion. The Rutelli Chapel offers a very interesting example of architecture that demonstrates several similarities with some Mamluk mausoleums in Cairo.

Representation, nation and time : the political rhetoric of the 1866 parliamentary reform in Sweden

2000

Sylviasta, Sylvialle, Sylviana : retoriikka ja merkityksenmuodostus osoitteessa www.sylviaplathforum.com

2016

This study explores the writings of Sylvia Plath Forum, a discussion forum in the Internet that was launched in 1998. Using Norman Fairclough’s critical discourse analysis, Chaïm Perelman’s theory of argumentation, Kenneth Burke’s idea of identification as the basis of rhetoric, and René Girards’s theory of mimetic desire as its framework this study looks into the forum’s meaning-making processes and the ways the author Sylvia Plath (1932-1963) and her readers are represented on the forum. Attention is paid especially to meaning-making practices that are connected with literary studies, feminism, medicalization, and cultic phenomena. Furthermore, cultic discourse and fan discourse are under…

IL SINDACO DEL RIONE SANITÀ – MIT WŁOSKIEGO GUAPPO OCZAMI LUIGIEGO PIRANDELLA

2015

The article proposes an analysis of one of the main plays written by Eduardo De Filippo, Il sindaco del rione Sanita, considered here in a wide context: the literary and artistic representation of Neapolitan criminality. Understood by a part of the critics and later by sociological studies focused on the camorra as the “personification of the myth” of the guappo, often in opposition to the parodistic and disenchanted version of the character offered by Raffaele Viviani, Eduardo’s Sindaco actually maintains with this topos an extensively ambiguous connection. In this essay, using the proper methods of textual analysis in a dialogue with some contributions taken from historiography and sociol…