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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Functional and comparative morphology of the pectoral fins among scorpaeniform fishes

Taft, Natalia K 01 January 2009 (has links)
Many benthic fishes use their pectoral fins for both swimming and substrate contact. Each behavior imposes different, potentially conflicting functional demands on the pectoral fins. It has been hypothesized that benthic fish decouple these demands through morphological and functional regionalization of the fins, but this hypothesis had not been experimentally tested. In this study, I demonstrated functional regionalization of the pectoral fin in the longhorn sculpin, Myoxocephalus octodecimspinosus, a benthic scorpaeniform fish. The ventral region of the pectoral fin is used during substrate contact; the dorsal region is used during swimming. I characterize a previously undescribed swimming behavior during which the pectoral fins are held in a steady, laterally extended posture while the dorsal, anal and caudal fins are used for propulsion. I also investigate the functional morphology of individual pectoral fin rays. I find that the curvature of the fin rays is higher in the ventral versus dorsal region of the fin, regardless of behavior. The fin rays of longhorn sculpin possess a previously undescribed morphology in cross-section. Specifically, the hemitrichia, or bony halves that make up the fin rays, are cylindrical in cross-section proximally and crescent-shaped distally. The cylindrical segments in the proximal regions of the fin rays of longhorn sculpin provide resistance to bending, which may confer strength and support for weight-bearing substrate-contact behaviors. Further, the ventral fin rays, which are used for substrate contact, have a higher proportion of their total length made up of cylindrical segments. Finally, I used a comparative approach to examine the distribution of morphological specializations and habitat (benthic or pelagic) of the pectoral fins among scorpaeniform fishes. I identified three discrete characters of the pectoral fins that are associated with a benthic habitat for analysis; (1) an asymmetrical fin membrane among ventral fin rays, (2) the presence of fin rays that are unbranched distally, and (3) the presence of ventral pectoral fin rays that are free of fin membrane. Each of these characters has evolved more than once among scorpaeniform fishes and is more common among benthic than pelagic fishes.
202

The Evolution of Sheng in Mainland China from 1949 to 2018

Qin, Haochen 15 September 2021 (has links)
No description available.
203

INNOVATION AND LOSS OF A NOVEL SENSORY ORGAN DURING EVOLUTIONARY TRANSITIONS AMONG ECOLOGICAL NICHES IN A PRAYING MANTIS LINEAGE

Brannoch, Sydney Kegan, Ph.D. 26 August 2019 (has links)
No description available.
204

Control and Characterization of Titanium Dioxide Morphology: Applications in Surface Organometallic Chemistry

Jeantelot, Gabriel 05 1900 (has links)
Surface Organometallic Chemistry leads to the combination of the high activity and specificity of homogeneous catalysts with the recoverability and practicality of heterogeneous catalysts. Most metal complexes used in this chemistry are grafted on metal oxide supports such as amorphous silica (SiO2) and γ-alumina (Al2O3). In this thesis, we sought to enable the use of titania (TiO2) as a new support for single-site well-defined grafting of metal complexes. This was achieved by synthesizing a special type of anatase-TiO2, bearing a high density of identical hydroxyl groups, through hydrothermal synthesis then post-treatment under high vacuum followed by oxygen flow, and characterized by several analytical techniques including X-ray diffraction, transmission electron microscopy, infrared spectroscopy and nuclear magnetic resonance. Finally, as a proof of concept, the grafting of vanadium oxychloride (VOCl3) was successfully attempted.
205

2D AND 3D SHAPE VARIATION AMONG ELASMOBRANCH OLFACTORY ROSETTES

Unknown Date (has links)
The functional impacts of olfactory rosette variation in elasmobranchs is unresolved. Our goal was to quantify rosette morphology and shape from 14 species using dissections, phylogenetic comparisons, and microCT imaging. We hypothesized that lamellar count and rosette shape (fineness ratio) would not scale with animal size, but internal rosette size variables must scale positively. We found that fineness ratio and lamellar counts varied significantly among species, and were positively correlated. The first two principal components of the pPCA explained 82% of the variation, with fineness ratio and lamellar count contributing the most. There were no significant differences between rosette structure or volume when comparing dissected values to in situ values obtained using diceCT. Based on our results, we hypothesize that variations in rosette shape and morphology will impact hydrodynamics and optimize odorant detection, and these data can be used to create 3D models for future hydrodynamic studies. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection
206

Robust Geometric Morphometric Analysis for Surface Meshes

Unknown Date (has links)
Geometric morphometrics has traditionally relied on named anatomical landmarks for the statistical analysis of shape, but that is changing. With the now-widespread availability of 3D surface and volumetric scanning technology, performing shape analysis using high-resolution 3D data is a very active area of research. The method described by Pomidor, Makedonska, and Slice (2016), Generalized Procrustes Surface Analysis (GPSA), is one of many new techniques to analyze the shape of objects using 3D surfaces instead of landmarks, but is still based on a generalized Procrustes framework. Frequently, surface-based shape analysis methods are limited by the topological properties of the objects being analyzed. In geometric morphometric data sets, one is often working with data sets where connectivity and number of boundary components may differ, and objects may or may not be closed. By continuing development as a generalization of multivariate shape analysis, it is possible to largely circumvent this problem. While methodologically sound, GPSA has several areas that could be improved. It is predicated on a basic version of the Iterative Closest Point (ICP) algorithm (a family of methods for image superimposition) and a simple, but weak, set of correspondence rules. This reduces the accuracy of the estimated homology and methods that rely on this estimation. GPSA also operates only on the cloud of points making up a surface and, if one exists, does not make use of the accompanying surface mesh, which makes it highly dependent on the distribution of points in space. The inclusion of a mesh has become relatively standard practice and can be used to significantly improve the superimposition and analysis by allowing calculation of metrics that describe the local shape. The methods for prototype deformation and homologization, both of which are reliant on the estimated homology, only use the prototype-to-sample homology for stability reasons, biasing any resultant analysis towards the mean. Finally, the cost function used during superimposition (point-to-plane ICP) is not derived from the distance metric (Procrustes Surface Metric) used to analyze the objects after superimposition. The two are closely related, so the distance metric is reduced as the ICP cost function is minimized, but they are not identical and thus the distance metric is not optimally minimized by the superimposition. Here, the same generalized Procrustes algorithmic structure used in GPSA is kept, but with several modifications made to offer a more accurate, more efficient, more robust method for surface-based statistical shape analysis. These modifications begin with re-deriving the cost function from a reformulated shape distance metric. This metric is based on the area-weighted vertices of one surface mesh and corresponding points on another mesh, rather than pairs of points in two point clouds. Local shape descriptors and λ|μ smoothing are used to improve the approximated homology. Efficiency is addressed with a better memory management model and a different implementation of the space partitioning tree. A newly defined metric helps determine the quality of a match between two points. These match quality values are used in a resistant-fit extension based on Trimmed ICP to emulate the outlier-resistant behavior of the Generalized Resistant-Fit superimposition method for landmark-based morphometrics. The method is then evaluated using several data sets. Some of these are artificial data sets generated using the Stanford bunny, a surface scan commonly used for testing mesh-based algorithms, while the rest are real-world data sets. These include scans of phytoliths, which are relatively smooth, featureless silicate structures found in plants and a key tool for paleobotanists in reconstructing ancient environments. The scanned phyotliths come from Anomochloa, a genus of grass-like Brazilian plants. The scans of small primate skulls originally used to test GPSA are also used in order to provide a way to compare this improved method to both GPSA and to Generalized Procrustes Analysis (GPA), the standard tool for landmark-based morphometric analysis. No attempt is made to draw any conclusions regarding the biological interpretation of these results; rather, these tests are used to make inferences about the properties of the analysis method. Some of this evaluation is qualitative, such as appraising how sound the topology of the resulting meshes are or interpreting heat maps. The shape distances between the surfaces generated or superimposed during the analysis are used as the basis for quantitative comparison. / A Dissertation submitted to the Department of Scientific Computing in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / 2019 / November 15, 2019. / Geometric morphometrics, Procrustes, Resistant-Fit, Shape analysis, Surface mesh / Includes bibliographical references. / Peter Beerli, Professor Directing Dissertation; Scott Steppan, University Representative; Nick Cogan, Committee Member; Anke Meyer-Baese, Committee Member; Sachin Shanbhag, Committee Member.
207

A comparative study of the influence of the nasal prefix `N' ( from UR- BANTU "NI-") on succeeding consonants at the beginning of some lexical items in Zulu, Xhosa and Southern Sotho

Lephallo, Amos Thabo January 1990 (has links)
Submitted in fulfillment for the Degree Master of Arts in the Department of African Languages at the University of Zululand, South Africa, 1990. / In any language, words are uttered systematically according to certain rules. Each language has therefore its own system. Language may be defined as "a system of utterances governed by a set of.rules". In a language there are partial systems such as Phonetics, Morphology, Syntax, etc. Wnen these partial systems are put together they form a unique system of a particular language. Phonetics is the study of a single speech sound. A word is made up of a number of phonetic units.
208

Les savoirs non académiques des antiquaires : contribution à une sociologie de l'irrégularité. / Non-academic learning of antique dealers : a contribution to a sociology of the unorthodox

Félix, Geoffroy 12 September 2016 (has links)
Cette étude porte sur le processus de circulation des objets anciens et des hommes dans des boutiques et galeries d’antiquaires à Paris. Le premier chapitre est consacré à une mise en perspective théorique de la notion de savoirs non académiques des antiquaires par le biais d’une enquête de terrain par entretiens semi-directifs. Il met l’accent sur le caractère baroque de l’activité des antiquaires et des effets que cela a pu engendrer sur l’enquête de terrain. Il s’agit de concevoir une théorie permettant de rendre compte de la contribution des antiquaires à la formation des prix et à la « création » de valeur pour des biens non homogènes échappant aux coûts de production « classiques ». Le second chapitre dessine les contours des lieux qui structurent la vie des antiquaires. Il analyse dans une première partie la façon d’entrer et de s’orienter dans un métier d’indépendants où la division du travail, fort peu marquée, voit les antiquaires connaître les heurs et malheurs que réservent tant la prospection que l’authentification des objets. Dans une seconde partie, une synthèse rend compte de la morphologie de l’antiquariat en insistant sur les dimensions langagière et spatiale qui l’organisent. Le troisième et dernier chapitre de la thèse est plus théorique. Il est centré sur la valeur des objets anciens et l’élaboration de leurs prix. Il est question de mettre au jour une double coordination des échanges afin de dégager le point d’articulation de la structure du marché de l’art ancien organisé par les antiquaires et de la dynamique du Marché en général. / The subject of this study is the circulation process of antique objects and of people in antique shops and galleries in Paris. Chapter 1 is devoted to establishing the notion of non-academic learning of antique dealers from a theoretical perspective by means of a field survey using semi-structured interviews. It emphasizes the peculiar nature of antique dealing, and the bearing that this aspect has had on the field survey. The object is to formulate a theory that explains how antique dealers contribute to the pricing and the « creation » of value of non-homogenous articles, that are exempt from « classic » production costs. Chapter 2 delineates the environment that structures the antique dealer’s life. Its first part analyses the manner in which you start out and orientate yourself in this very independent trade, where division of labour is practically non-existent, leading to the fortunes, reverse of fortunes, and misfortunes connected with prospecting for and authentifying objects. Its second part is a synthesis which reflects the morphology of antique dealing, stressing the linguistic and spatial dimensions inherent to its organization. The 3rd and last chapter is more theoretical. It focuses on the value of antique objects and determining their price. The idea is to bring to light a double coordination of transactions in order to uncover the hinge point between the specific structure of the antiques market as organized by the dealers and the supply and demand dynamics of trade in general.
209

The Evolution of Wing Pattern in Micropterigidae (Insecta: Lepidoptera)

Schachat, Sandra Rose 12 August 2016 (has links)
Despite the biological importance of lepidopteran wing patterns, homologies between pattern elements in different lineages are still not understood. Though plesiomorphic wing veins influence color patterning even when not expressed in the adult wing, most studies of wing pattern evolution have focused on derived taxa with reduced venation. Here I address this gap with an examination of Micropterigidae, a very early-diverged family in which all known plesiomorphic lepidopteran veins are expressed in the adult wing. Differences between the coloration of transverse bands in Micropterix and Sabatinca suggest that homologies exist between the contrast boundaries that divide wing pattern elements. Because the wing pattern of Sabatinca doroxena very closely resembles the nymphalid groundplan when plotted onto a hypothetical nymphalid wing following the relationship between pattern and venation discussed here, it appears that the nymphalid groundplan may have originated from a Sabatinca-like wing pattern subjected to changes in wing shape.
210

The outline of a theory of morphology /

Walsh, Linda. January 1981 (has links)
No description available.

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