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Three-dimensional Representations (three-dimensional + representation)
Selected AbstractsThree-Dimensional Representation of the Neurotransmitter Systems of the Human Hypothalamus: Inputs of the Gonadotrophin Hormone-Releasing Hormone Neuronal SystemJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2006B. Dudas Abstract The gonadotrophin-releasing hormone (GnRH) represents the final common pathway of a neuronal network that integrates multiple external and internal factors to control fertility. Among the many inputs GnRH neurones receive, oestrogens play the most important role. In females, oestrogen, in addition to the negative feedback, also exhibits a positive feedback influence upon the activity and output of GnRH neurones to generate the preovulatory luteinising hormone surge and ovulation. Until recently, the belief has been that the GnRH neurones do not contain oestrogen receptors and that the action of oestrogen upon GnRH neurones is indirect, involving several, oestrogen-sensitive neurotransmitter and neuromodulator systems that trans -synaptically regulate the activity of the GnRH neurones. Although this concept still holds for humans, recent studies indicate that oestrogen receptor-beta is expressed in GnRH neurones of the rat. This review provides three dimensional stereoscopic images of GnRH-immunoreactive (IR) and some peptidergic (neuropeptide Y-, substance P-, ,-endorphin-, leu-enkaphalin-, corticotrophin hormone-releasing- and galanin-IR) and catecholaminergic neurones and the communication of these potential oestrogen-sensitive neuronal systems with GnRH neurones in the human hypothalamus. Because the post-mortem human tissue does not allow the electron microscopic identification of synapses on GnRH neurones, the data presented here are based on light microscopic immunocytochemical experiments using high magnification with oil immersion, semithin sections or confocal microscopy. [source] Three-dimensional representation of curved nanowiresJOURNAL OF MICROSCOPY, Issue 3 2004Z. HUANG Summary Nanostructures, such as nanowires, nanotubes and nanocoils, can be described in many cases as quasi one-dimensional curved objects projecting in three-dimensional space. A parallax method to construct the correct three-dimensional geometry of such one-dimensional nanostructures is presented. A series of scanning electron microscope images was acquired at different view angles, thus providing a set of image pairs that were used to generate three-dimensional representations using a matlab program. An error analysis as a function of the view angle between the two images is presented and discussed. As an example application, the importance of knowing the true three-dimensional shape of boron nanowires is demonstrated; without the nanowire's correct length and diameter, mechanical resonance data cannot provide an accurate estimate of Young's modulus. [source] SAXSANA: an interactive program for the analysis and monitoring of static and time-resolved small-angle X-ray solution scattering measurementsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2003Yuzuru Hiragi An interactive analytical program, SAXSANA, for small-angle X-ray scattering measurements of solutions is described. The program processes scattered data without disciplined knowledge of small-angle scattering. SAXSANA also assists in finding the best experimental conditions, thus avoiding blind runs of experiments. SAXSANA consists of the following procedures: (i) determination of the centre of scattered X-rays and moment transfer Q (Q,=,4,sin,/,, where 2, is the scattering angle and , is the wavelength) for each measured channel; (ii) conversion of the data format to the format of Q versus scattered intensities J(Q); (iii) truncation of unnecessary data and smoothing of scattering curves by cubic-spline function; (iv) correction of the absorption effect and subtraction of the scattered intensity of the buffer (solvent) solution from that of the sample solution; (v) creation of a data file for a three-dimensional representation of time-resolved scattering curves; (vi) determination of radii of gyration by Guinier plots; (vii) determination of persistent lengths by Kratky plots; (viii) extrapolation of the small-angle part by Guinier plots; (ix) extrapolation of the wide-angle part by Porod's & Luzzati's laws for the Hankel transformation in order to obtain the distance distribution function p(r); (x) calculation of p(r) and computation of the invariant, the chord length, the volume, the spherical radius, the maximum dimension Dmax and the radius of gyration (Rg). SAXSANA also serves as an on-site monitor for the validity of an experimental result during the measurements. [source] Understanding Young Children's Three-Dimensional Creative Potential in Art MakingINTERNATIONAL JOURNAL OF ART & DESIGN EDUCATION, Issue 2 2009Victoria Pavlou This article explores aspects of young children's three-dimensional development in art making. Understanding young children's three-dimensional awareness and development is often a neglected area of early childhood educators' education and practice and often children's creative potential is not fully realised. The present article is based on a small scale qualitative study which focused on understanding 5,6 year-olds' representational intentions in three-dimensional artworks, understanding of visual/design concepts and expressive use of media (scrap paper and mod roc). The findings of the study suggest that young children are able to create satisfying three-dimensional representations giving emphasis on forms, uprightness, balance, movement and modeling of multiple sides. [source] Three-dimensional representation of curved nanowiresJOURNAL OF MICROSCOPY, Issue 3 2004Z. HUANG Summary Nanostructures, such as nanowires, nanotubes and nanocoils, can be described in many cases as quasi one-dimensional curved objects projecting in three-dimensional space. A parallax method to construct the correct three-dimensional geometry of such one-dimensional nanostructures is presented. A series of scanning electron microscope images was acquired at different view angles, thus providing a set of image pairs that were used to generate three-dimensional representations using a matlab program. An error analysis as a function of the view angle between the two images is presented and discussed. As an example application, the importance of knowing the true three-dimensional shape of boron nanowires is demonstrated; without the nanowire's correct length and diameter, mechanical resonance data cannot provide an accurate estimate of Young's modulus. [source] A new high-resolution computed tomography (CT) segmentation method for trabecular bone architectural analysisAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Heike Scherf Abstract In the last decade, high-resolution computed tomography (CT) and microcomputed tomography (micro-CT) have been increasingly used in anthropological studies and as a complement to traditional histological techniques. This is due in large part to the ability of CT techniques to nondestructively extract three-dimensional representations of bone structures. Despite prior studies employing CT techniques, no completely reliable method of bone segmentation has been established. Accurate preprocessing of digital data is crucial for measurement accuracy, especially when subtle structures such as trabecular bone are investigated. The research presented here is a new, reproducible, accurate, and fully automated computerized segmentation method for high-resolution CT datasets of fossil and recent cancellous bone: the Ray Casting Algorithm (RCA). We compare this technique with commonly used methods of image thresholding (i.e., the half-maximum height protocol and the automatic, adaptive iterative thresholding procedure). While the quality of the input images is crucial for conventional image segmentation, the RCA method is robust regarding the signal to noise ratio, beam hardening, ring artifacts, and blurriness. Tests with data of extant and fossil material demonstrate the superior quality of RCA compared with conventional thresholding procedures, and emphasize the need for careful consideration of optimal CT scanning parameters. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||