WorldWideScience

Sample records for geometric morphometric approach

  1. Dietary ecology of Murinae (Muridae, Rodentia): a geometric morphometric approach.

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    Gómez Cano, Ana Rosa; Hernández Fernández, Manuel; Alvarez-Sierra, M Ángeles

    2013-01-01

    Murine rodents represent a highly diverse group, which displays great ecological versatility. In the present paper we analyse the relationship between dental morphology, on one hand, using geometric morphometrics based upon the outline of first upper molar and the dietary preference of extant murine genera, on the other. This ecomorphological study of extant murine rodents demonstrates that dietary groups can be distinguished with the use of a quantitative geometric morphometric approach based on first upper molar outline. A discriminant analysis of the geometric morphometric variables of the first upper molars enables us to infer the dietary preferences of extinct murine genera from the Iberian Peninsula. Most of the extinct genera were omnivore; only Stephanomys showed a pattern of dental morphology alike that of the herbivore genera.

  2. Dietary ecology of Murinae (Muridae, Rodentia: a geometric morphometric approach.

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    Ana Rosa Gómez Cano

    Full Text Available Murine rodents represent a highly diverse group, which displays great ecological versatility. In the present paper we analyse the relationship between dental morphology, on one hand, using geometric morphometrics based upon the outline of first upper molar and the dietary preference of extant murine genera, on the other. This ecomorphological study of extant murine rodents demonstrates that dietary groups can be distinguished with the use of a quantitative geometric morphometric approach based on first upper molar outline. A discriminant analysis of the geometric morphometric variables of the first upper molars enables us to infer the dietary preferences of extinct murine genera from the Iberian Peninsula. Most of the extinct genera were omnivore; only Stephanomys showed a pattern of dental morphology alike that of the herbivore genera.

  3. Sexual Dimorphism of the First Rib: A Comparative Approach Using Metric and Geometric Morphometric Analyses.

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    Lynch, Jeffrey James; Cross, Peter; Heaton, Vivienne

    2017-09-01

    This research investigated the sexual dimorphism of the first human rib using geometric morphometric and metric approaches on a sample of 285 specimens containing European Americans and African Americans from the Hamann-Todd collection. Metric measurements were investigated for sexual dimorphism and ancestral differences using univariate statistics. Four type II landmarks and 40 sliding semi-landmarks were placed outlining the dorsal and ventral curvatures of the ribs. Landmark data were processed using Generalized Procrustes Analyses with Procrustes distance sliding, and the subsequent coordinates were investigated for sexual dimorphism and ancestral differences using Procrustes ANOVAs. Both geometric morphometric and metric data were analyzed using cross-validated discriminant function analyses to test the hypothesis that variables from both approaches can be combined to increase sex classification rate. European Americans had sex correctly classified as high as 88.05% and African Americans as high as 70.86% using a combination of metric and geometric morphometric variables. © 2017 American Academy of Forensic Sciences.

  4. Bat Species Comparisons Based on External Morphology: A Test of Traditional versus Geometric Morphometric Approaches

    OpenAIRE

    2015-01-01

    External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species – in this case European horse...

  5. Bat Species Comparisons Based on External Morphology: A Test of Traditional versus Geometric Morphometric Approaches

    Science.gov (United States)

    Schmieder, Daniela A.; Benítez, Hugo A.; Borissov, Ivailo M.; Fruciano, Carmelo

    2015-01-01

    External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species – in this case European horseshoe bats (Rhinolophidae, Chiroptera) – based on morphology of the wing, body and tail. In addition to comparing morphometric methods, we used geometric morphometrics to detect interspecies differences as shape changes. Geometric morphometrics yielded improved species discrimination relative to traditional methods. The predicted shape for the variation along the between group principal components revealed that the largest differences between species lay in the extent to which the wing reaches in the direction of the head. This strong trend in interspecific shape variation is associated with size, which we interpret as an evolutionary allometry pattern. PMID:25965335

  6. Bat Species Comparisons Based on External Morphology: A Test of Traditional versus Geometric Morphometric Approaches.

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    Daniela A Schmieder

    Full Text Available External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species--in this case European horseshoe bats (Rhinolophidae, Chiroptera--based on morphology of the wing, body and tail. In addition to comparing morphometric methods, we used geometric morphometrics to detect interspecies differences as shape changes. Geometric morphometrics yielded improved species discrimination relative to traditional methods. The predicted shape for the variation along the between group principal components revealed that the largest differences between species lay in the extent to which the wing reaches in the direction of the head. This strong trend in interspecific shape variation is associated with size, which we interpret as an evolutionary allometry pattern.

  7. Bat Species Comparisons Based on External Morphology: A Test of Traditional versus Geometric Morphometric Approaches.

    Science.gov (United States)

    Schmieder, Daniela A; Benítez, Hugo A; Borissov, Ivailo M; Fruciano, Carmelo

    2015-01-01

    External morphology is commonly used to identify bats as well as to investigate flight and foraging behavior, typically relying on simple length and area measures or ratios. However, geometric morphometrics is increasingly used in the biological sciences to analyse variation in shape and discriminate among species and populations. Here we compare the ability of traditional versus geometric morphometric methods in discriminating between closely related bat species--in this case European horseshoe bats (Rhinolophidae, Chiroptera)--based on morphology of the wing, body and tail. In addition to comparing morphometric methods, we used geometric morphometrics to detect interspecies differences as shape changes. Geometric morphometrics yielded improved species discrimination relative to traditional methods. The predicted shape for the variation along the between group principal components revealed that the largest differences between species lay in the extent to which the wing reaches in the direction of the head. This strong trend in interspecific shape variation is associated with size, which we interpret as an evolutionary allometry pattern.

  8. Measurement error in geometric morphometrics.

    Science.gov (United States)

    Fruciano, Carmelo

    2016-06-01

    Geometric morphometrics-a set of methods for the statistical analysis of shape once saluted as a revolutionary advancement in the analysis of morphology -is now mature and routinely used in ecology and evolution. However, a factor often disregarded in empirical studies is the presence and the extent of measurement error. This is potentially a very serious issue because random measurement error can inflate the amount of variance and, since many statistical analyses are based on the amount of "explained" relative to "residual" variance, can result in loss of statistical power. On the other hand, systematic bias can affect statistical analyses by biasing the results (i.e. variation due to bias is incorporated in the analysis and treated as biologically-meaningful variation). Here, I briefly review common sources of error in geometric morphometrics. I then review the most commonly used methods to measure and account for both random and non-random measurement error, providing a worked example using a real dataset.

  9. Host evolution in Mastomys natalensis (Rodentia: Muridae): An integrative approach using geometric morphometrics and genetics.

    Science.gov (United States)

    Lalis, Aude; Evin, Allowen; Janier, Marc; Koivogui, Lamine; Denys, Christiane

    2015-11-01

    The commensal rodent Mastomys natalensis is the natural reservoir of Lassa arenavirus (LASV), which causes hemorrhagic fever in West Africa. To study a possible effect of the virus on phenotypic and genotypic variation of its persistently infected host, we compared LASV-positive and non-infected wild-caught M. natalensis. The LASV effects on the phenotypic variation were explored using standard external morphometric measurements, geometric morphometric analyses of the cranial size and shape, and brain case volume. The genetic variability of M. natalensis specimens was assessed using 9 polymorphic microsatellite markers. Independent of sex and age, LASV-infected animals had smaller external body measurements, reproductive organs, skull size and brain case volume. Cranial shape differences between the 2 groups are represented by a lateral constriction of the entire skull. The genetic variability revealed consanguinity only among the LASV-positive rodents. We hypothesize that growth impairment may result in a selective disadvantage for LASV-infected M. natalensis, leading to a preferably commensal lifestyle in areas where the LAVS is endemic and, thereby, increasing the risk of LASV transmission to humans. © 2015 International Society of Zoological Sciences, Institute of Zoology/Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

  10. Functional morphology and integration of corvid skulls – a 3D geometric morphometric approach

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    Gunz Philipp

    2009-01-01

    Full Text Available Abstract Background Sympatric corvid species have evolved differences in nesting, habitat choice, diet and foraging. Differences in the frequency with which corvid species use their repertoire of feeding techniques is expected to covary with bill-shape and with the frontal binocular field. Species that frequently probe are expected to have a relatively longer bill and more sidewise oriented orbits in contrast to species that frequently peck. We tested this prediction by analyzing computed tomography scans of skulls of six corvid species by means of three-dimensional geometric morphometrics. We (1 explored patterns of major variation using principal component analysis, (2 compared within and between species relationships of size and shape and (3 quantitatively compared patterns of morphological integration between bill and cranium by means of partial least squares (singular warp analysis. Results Major shape variation occurs at the bill, in the orientation of orbits, in the position of the foramen magnum and in the angle between bill and cranium. The first principal component correlated positively with centroid-size, but within-species allometric relationships differed markedly. Major covariation between the bill and cranium lies in the difference in orbit orientation relative to bill-length and in the angle between bill and cranium. Conclusion Corvid species show pronounced differences in skull shape, which covary with foraging mode. Increasing bill-length, bill-curvature and sidewise orientation of the eyes is associated with an increase in the observed frequency in probing (vice versa in pecking. Hence, the frequency of probing, bill-length, bill-curvature and sidewise orientation of the eyes is progressively increased from jackdaw, to Eurasian jay, to black-billed magpie, to hooded crow, to rook and to common raven (when feeding on carcasses is considered as probing. Our results on the morphological integration suggest that most of the

  11. Re-description and Reassignment of the Damselfish Abudefduf luridus (Cuvier, 1830) Using Both Traditional and Geometric Morphometric Approaches

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, W. James [Washington State Univ., Pullman, WA (United States); Albertson, R Craig [Univ. of Massachusetts, Amherst, MA (United States); Jacob, Rick E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westneat, Mark W. [Field Museum of Natural History, Chicago, IL (United States)

    2014-12-01

    Here we present a re-description of Abudefduf luridus and reassign it to the genus Similiparma. We supplement traditional diagnoses and descriptions of this species with quantitative anatomical data collected from a family-wide geometric morphometric analysis of head morphology (44 species representing all 30 damselfish genera) and data from cranial micro-CT scans of fishes in the genus Similiparma. The use of geometric morphometric analyses (and other methods of shape analysis) permits detailed comparisons between the morphology of specific taxa and the anatomical diversity that has arisen in an entire lineage. This provides a particularly useful supplement to traditional description methods and we recommend the use of such techniques by systematists. Similiparma and its close relatives constitute a branch of the damselfish phylogenetic tree that predominantly inhabits rocky reefs in the Atlantic and Eastern Pacific, as opposed to the more commonly studied damselfishes that constitute a large portion of the ichthyofauna on all coral-reef communities.

  12. A morphometric approach in breast cytology--geometrical descriptors in the differentiation between benign and malignant lesions.

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    Mihalache, Daniela; Giuşcă, Simona Eliza; Balan, Raluca; Amălinei, Cornelia; Grigoraş, Adriana; Căruntu, Irina Draga

    2014-01-01

    This study focuses on the analysis of geometric descriptors that can be applied in breast cytology, and their correlation with the qualitative features, with the aim to underline the differences between the benign and malignant cell profile. The morphometric investigation was performed on smears obtained by fine needle aspiration, 10 cases (group 1) diagnosed as benign and 10 cases (group 2) as malignant. For group 2, the malignancy was histopathologically confirmed on the surgical resection specimen. The sequence of automated operation, previously reported by us, permitted the extraction of the following geometrical descriptors: cytoplasmic area, nuclear area, nucleo-cytoplasmic ratio, equivalent diameter and form factor. We analyzed the differences between the benign and malignant morphometric features, and the correlation between the malignant morphometric features and cytological, respectively histological grading. Statistically significant difference in cytoplasmic areas, nuclear areas, value of nucleo-cytoplasmic ratio and equivalent diameter was noted between group I and II. For the form factor, we did not register statistically significant differences. For group 2, the correlation between the morphometric features and cytological grading revealed that the nuclear area is the most valuable descriptor, due to the significant differences between the three successive grades of cytological severity, followed by the cytoplasmic area and equivalent diameter, their numerical values presenting significant differences between cytological grade 1 and 3, and 2 and 3, respectively. The statistical analysis between the morphometric features and histological grading showed that nuclear area and equivalent diameter are the most viable indicators, due to the significant differences present between the three successive grades of pathologic severity, followed by cytoplasmic area (significant differences only for grade 2 versus 3) and for nucleo-cytoplasmic ratio (significant

  13. Geometric morphometrics of hominoid infraspinous fossa shape.

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    Green, David J; Serrins, Jesse D; Seitelman, Brielle; Martiny, Amy R; Gunz, Philipp

    2015-01-01

    Recent discoveries of early hominin scapulae from Ethiopia (Dikika, Woranso-Mille) and South Africa (Malapa) have motivated new examinations of the relationship between scapular morphology and locomotor function. In particular, infraspinous fossa shape has been shown to significantly differ among hominoids. However, this region presents relatively few homologous landmarks, such that traditional distance and angle-based methods may oversimplify this three-dimensional structure. To more thoroughly assess infraspinous fossa shape variation as it relates to function among adult hominoid representatives, we considered two geometric morphometric (GM) approaches--one employing five homologous landmarks ("wireframe") and another with 83 sliding semilandmarks along the border of the infraspinous fossa. We identified several differences in infraspinous fossa shape with traditional approaches, particularly in superoinferior fossa breadth and scapular spine orientation. The wireframe analysis reliably captured the range of shape variation in the sample, which reflects the relatively straightforward geometry of the infraspinous fossa. Building on the traditional approach, the GM results highlighted how the orientation of the medial portion of the infraspinous fossa differed relative to both the axillary border and spine. These features distinguished Pan from Gorilla in a way that traditional analyses had not been able to discern. Relative to the wireframe method, the semilandmark approach further distinguished Pongo from Homo, highlighting aspects of infraspinous fossa morphology that may be associated with climbing behaviors in hominoid taxa. These results highlight the ways that GM methods can enhance our ability to evaluate complex aspects of shape for refining and testing hypotheses about functional morphology.

  14. Shape and size variations of Aegla uruguayana (Anomura, Aeglidae under laboratory conditions: A geometric morphometric approach to the growth

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    Valeria P. Diawol

    2015-03-01

    Full Text Available Crustacean growth studies typically use modal analysis rather than focusing on the growth of individuals. In the present work, we use geometric morphometrics to determine how organism shape and size varies during the life of the freshwater crab, Aegla uruguayana Schmitt, 1942. A total of 66 individuals from diverse life cycle stages were examined daily and each exuvia was recorded. Digital images of the dorsal region of the cephalothorax were obtained for each exuvia and were subsequently used to record landmark configurations. Moult increment and intermoult period were estimated for each crab. Differences in shape between crabs of different sizes (allometry and sexes (sexual dimorphism; SD were observed. Allometry was registered among specimens; however, SD was not statistically significant between crabs of a given size. The intermoult period increased as size increased, but the moult frequency was similar between the sexes. Regarding ontogeny, juveniles had short and blunt rostrum, robust forehead region, and narrow cephalothorax. Unlike juveniles crabs, adults presented a well-defined anterior and posterior cephalothorax region. The rostrum was long and stylised and the forehead narrow. Geometric morphometric methods were highly effective for the analysis of aeglid-individual- growth and avoided excessive handling of individuals through exuvia analysis.

  15. Social Complexification and Pig (Sus scrofa) Husbandry in Ancient China: A Combined Geometric Morphometric and Isotopic Approach.

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    Cucchi, Thomas; Dai, Lingling; Balasse, Marie; Zhao, Chunqing; Gao, Jiangtao; Hu, Yaowu; Yuan, Jing; Vigne, Jean-Denis

    2016-01-01

    Pigs have played a major role in the economic, social and symbolic systems of China since the Early Neolithic more than 8,000 years ago. However, the interaction between the history of pig domestication and transformations in Chinese society since then, have not been fully explored. In this paper, we investigated the co-evolution from the earliest farming communities through to the new political and economic models of state-like societies, up to the Chinese Empire, using 5,000 years of archaeological records from the Xiawanggang (XWG) and Xinzhai (XZ) sites (Henan Province). To trace the changes of pig populations against husbandry practices, we combined the geometric morphometric analysis of dental traits with a study of the stable carbon and nitrogen isotope ratios from bone collagen. The domestication process intensified during the Neolithic Yangshao, prompted by greater selective pressure and/or better herd control against wild introgression. After that, pig farming, in XWG, relied on local livestock and a gradual change of husbandry practices overtime. This was characterized by a gentle increase in millet foddering and animal protein intake, until a complete change over to household management during the Han dynasty. The only rupture in this steady trend of husbandry occurred during the Longshan period, with the appearance of small sized and idiosyncratic pigs with specific feeding practices (relying on millet and household scraps). From three exploratory hypothesis, we explored the possibility of anti-elite pig production in XWG during the Longshan period, as a means to resist incorporation into a new economic model promoting intensified domestic production. This exploratory hypothesis is the most suitable to our dataset; however, numerous areas need to be explored further in order to adequately document the role of pigs in the rise of China's complex societies.

  16. Evolution of neck vertebral shape and neck retraction at the transition to modern turtles: an integrated geometric morphometric approach.

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    Werneburg, Ingmar; Wilson, Laura A B; Parr, William C H; Joyce, Walter G

    2015-03-01

    The unique ability of modern turtles to retract their head and neck into the shell through a side-necked (pleurodiran) or hidden-necked (cryptodiran) motion is thought to have evolved independently in crown turtles. The anatomical changes that led to the vertebral shapes of modern turtles, however, are still poorly understood. Here we present comprehensive geometric morphometric analyses that trace turtle vertebral evolution and reconstruct disparity across phylogeny. Disparity of vertebral shape was high at the dawn of turtle evolution and decreased after the modern groups evolved, reflecting a stabilization of morphotypes that correspond to the two retraction modes. Stem turtles, which had a very simple mode of retraction, the lateral head tuck, show increasing flexibility of the neck through evolution towards a pleurodiran-like morphotype. The latter was the precondition for evolving pleurodiran and cryptodiran vertebrae. There is no correlation between the construction of formed articulations in the cervical centra and neck mobility. An increasing mobility between vertebrae, associated with changes in vertebral shape, resulted in a more advanced ability to retract the neck. In this regard, we hypothesize that the lateral tucking retraction of stem turtles was not only the precondition for pleurodiran but also of cryptodiran retraction. For the former, a kink in the middle third of the neck needed to be acquired, whereas for the latter modification was necessary between the eighth cervical vertebra and first thoracic vertebra. Our paper highlights the utility of 3D shape data, analyzed in a phylogenetic framework, to examine the magnitude and mode of evolutionary modifications to vertebral morphology. By reconstructing and visualizing ancestral anatomical shapes, we provide insight into the anatomical features underlying neck retraction mode, which is a salient component of extant turtle classification. © The Author(s) 2014. Published by Oxford University Press

  17. Geometric morphometric analysis reveals sexual dimorphism in the distal femur.

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    Cavaignac, Etienne; Savall, Frederic; Faruch, Marie; Reina, Nicolas; Chiron, Philippe; Telmon, Norbert

    2016-02-01

    An individual's sex can be determined by the shape of their distal femur. The goal of this study was to show that differences in distal femur shape related to sexual dimorphism could be identified, visualized, and quantified using 3D geometric morphometric analysis. Geometric morphometric analysis was carried out on CT scans of the distal femur of 256 subjects living in the south of France. Ten landmarks were defined on 3D reconstructions of the distal femur. Both traditional metric and geometric morphometric analyses were carried out on these bone reconstructions; these analyses identified trends in bone shape in sex-based subgroups. Sex-related differences in shape were statistically significant. The subject's sex was correctly assigned in 77.3% of cases using geometric morphometric analysis. This study has shown that geometric morphometric analysis of the distal femur is feasible and has revealed sexual dimorphism differences in this bone segment. This reliable, accurate method could be used for virtual autopsy and be used to perform diachronic and interethnic comparisons. Moreover, this study provides updated morphometric data for a modern population in the south of France. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  18. Fused traditional and geometric morphometrics demonstrate pinniped whisker diversity.

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    Ginter, Carly C; DeWitt, Thomas J; Fish, Frank E; Marshall, Christopher D

    2012-01-01

    Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length) were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics) was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC), which results in

  19. Fused Traditional and Geometric Morphometrics Demonstrate Pinniped Whisker Diversity

    Science.gov (United States)

    Ginter, Carly C.; DeWitt, Thomas J.; Fish, Frank E.; Marshall, Christopher D.

    2012-01-01

    Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length) were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics) was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC), which results in

  20. Fused traditional and geometric morphometrics demonstrate pinniped whisker diversity.

    Directory of Open Access Journals (Sweden)

    Carly C Ginter

    Full Text Available Vibrissae (whiskers are important components of the mammalian tactile sensory system, and primarily function as detectors of vibrotactile information from the environment. Pinnipeds possess the largest vibrissae among mammals and their vibrissal hair shafts demonstrate a diversity of shapes. The vibrissae of most phocid seals exhibit a beaded morphology with repeating sequences of crests and troughs along their length. However, there are few detailed analyses of pinniped vibrissal morphology, and these are limited to a few species. Therefore, we comparatively characterized differences in vibrissal hair shaft morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods. Traditional morphometric measurements (peak-to-peak distance, crest width, trough width and total length were collected using digital photographs. Elliptic Fourier analysis (geometric morphometrics was used to quantify the outlines of whole vibrissae. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to their species based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. Phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Otariids split into two groups in the geometric morphometric analysis and gray seals appeared intermediate between beaded- and smooth-whiskered species in the traditional and combined analyses. Vibrissal hair shafts modulate the transduction of environmental stimuli to the mechanoreceptors in the follicle-sinus complex (F-SC, which

  1. Studying developmental variation with Geometric Morphometric Image Analysis (GMIA).

    Science.gov (United States)

    Mayer, Christine; Metscher, Brian D; Müller, Gerd B; Mitteroecker, Philipp

    2014-01-01

    The ways in which embryo development can vary across individuals of a population determine how genetic variation translates into adult phenotypic variation. The study of developmental variation has been hampered by the lack of quantitative methods for the joint analysis of embryo shape and the spatial distribution of cellular activity within the developing embryo geometry. By drawing from the strength of geometric morphometrics and pixel/voxel-based image analysis, we present a new approach for the biometric analysis of two-dimensional and three-dimensional embryonic images. Well-differentiated structures are described in terms of their shape, whereas structures with diffuse boundaries, such as emerging cell condensations or molecular gradients, are described as spatial patterns of intensities. We applied this approach to microscopic images of the tail fins of larval and juvenile rainbow trout. Inter-individual variation of shape and cell density was found highly spatially structured across the tail fin and temporally dynamic throughout the investigated period.

  2. Geometric morphometrics of different malocclusions in lateral skull radiographs.

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    Freudenthaler, Josef; Čelar, Aleš; Ritt, Christopher; Mitteröcker, Philipp

    2017-01-01

    To evaluate the role of craniofacial shape in malocclusion by application of geometric morphometrics to a set of two-dimensional landmarks and semilandmarks obtained from lateral skull radiographs. Cephalometric radiograph tracings of 88 untreated Caucasians (age range 7-39 years) were assigned to four groups according to their occlusion: neutrocclusion, distocclusion, mesiocclusion, and anterior open bite. The geometric morphometric shape analysis incorporated 66 landmarks and semilandmarks, which underwent generalized Procrustes analysis, between-groups principal component analysis, thin-plate spline deformation grid visualization, permutation tests, and receiver operating characteristic curves. The position and shape of the mandible contributed to differences between the distocclusion and mesiocclusion groups, whereas the maxillary shape showed less variation. The growth-related shape alteration during adolescence was most pronounced in the mesiocclusion group and least pronounced in the neutrocclusion group. The open bite group was associated with an altered orientation of the mandibular body and the maxilla,  showed the most hyperdivergent maxillomandibular pattern but was not an own skeletal entity. Despite clear differences in mean shape across the four groups, the individual distribution of craniofacial shape overlapped between the groups without discrete clusters. Craniofacial shape was clearly associated with dental malocclusion and showed considerable variation. Geometric morphometrics was a powerful research tool but for diagnosing individual malocclusion standard cephalometric measurements including overjet and overbite were equally or more efficient than geometric morphometric descriptors.

  3. Studying developmental variation with Geometric Morphometric Image Analysis (GMIA.

    Directory of Open Access Journals (Sweden)

    Christine Mayer

    Full Text Available The ways in which embryo development can vary across individuals of a population determine how genetic variation translates into adult phenotypic variation. The study of developmental variation has been hampered by the lack of quantitative methods for the joint analysis of embryo shape and the spatial distribution of cellular activity within the developing embryo geometry. By drawing from the strength of geometric morphometrics and pixel/voxel-based image analysis, we present a new approach for the biometric analysis of two-dimensional and three-dimensional embryonic images. Well-differentiated structures are described in terms of their shape, whereas structures with diffuse boundaries, such as emerging cell condensations or molecular gradients, are described as spatial patterns of intensities. We applied this approach to microscopic images of the tail fins of larval and juvenile rainbow trout. Inter-individual variation of shape and cell density was found highly spatially structured across the tail fin and temporally dynamic throughout the investigated period.

  4. Morphological affinities of the proximal humerus of Epipliopithecus vindobonensis and Pliopithecus antiquus: suspensory inferences based on a 3D geometric morphometrics approach.

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    Arias-Martorell, Julia; Alba, David M; Potau, Josep M; Bello-Hellegouarch, Gaëlle; Pérez-Pérez, Alejandro

    2015-03-01

    Suspension plays a major adaptive role in shaping primate postcranial morphology, which therefore enables this positional behavior to be inferred in extinct taxa. The proximal humerus stands as a key region for inferring forelimb suspensory capabilities because its morphology can be effectively linked, from a functional viewpoint, to differences in suspension use between primate taxa. Here we provide an assessment of the suspensory capabilities of two pliopithecoids (Epipliopithecus vindobonensis and Pliopithecus antiquus) by means of a 3D geometric morphometric analysis of proximal humeral shape. The comparative sample includes proximal humeri from eight extant anthropoid genera, as well as other extinct catarrhines (the propliopithecoid Aegyptopithecus zeuxis, the stem hominoid Nyanzapithecus vancouveringorum, and an unascribed small catarrhine, GSP 28062, from the Middle Miocene of Pakistan). Body mass estimates based on allometric regressions of humeral head superoinferior diameter are also provided. Our results support some degree of forelimb suspensory behaviors for Epipliopithecus and GSP 28062. In contrast, and unlike previous qualitative assessments, our analysis shows that P. antiquus has a distinct glenohumeral morphology, much closer to that displayed by generalized arboreal quadrupeds with no evidence of suspensory adaptations (as in Aegyptopithecus and stem hominoids from Africa).

  5. The Utility of Geometric Morphometrics to Elucidate Pathways of Cichlid Fish Evolution

    Directory of Open Access Journals (Sweden)

    Michaela Kerschbaumer

    2011-01-01

    Full Text Available Fishes of the family Cichlidae are famous for their spectacular species flocks and therefore constitute a model system for the study of the pathways of adaptive radiation. Their radiation is connected to trophic specialization, manifested in dentition, head morphology, and body shape. Geometric morphometric methods have been established as efficient tools to quantify such differences in overall body shape or in particular morphological structures and meanwhile found wide application in evolutionary biology. As a common feature, these approaches define and analyze coordinates of anatomical landmarks, rather than traditional counts or measurements. Geometric morphometric methods have several merits compared to traditional morphometrics, particularly for the distinction and analysis of closely related entities. Cichlid evolutionary research benefits from the efficiency of data acquisition, the manifold opportunities of analyses, and the potential to visualize shape changes of those landmark-based methods. This paper briefly introduces to the concepts and methods of geometric morphometrics and presents a selection of publications where those techniques have been successfully applied to various aspects of cichlid fish diversification.

  6. Morphological Discrimination of Greek Honey Bee Populations Based on Geometric Morphometrics Analysis of Wing Shape

    Directory of Open Access Journals (Sweden)

    Charistos Leonidas

    2014-06-01

    Full Text Available Honey bees collected from 32 different localities in Greece were studied based on the geometric morphometrics approach using the coordinates of 19 landmarks located at wing vein intersections. Procrustes analysis, principal component analysis, and Canonical variate analysis (CVA detected population variability among the studied samples. According to the Principal component analysis (PCA of pooled data from each locality, the most differentiated populations were the populations from the Aegean island localities Astypalaia, Chios, and Kythira. However, the populations with the most distant according to the canonical variate analysis performed on all measurements were the populations from Heraklion and Chania (both from Crete island. These results can be used as a starting point for the use of geometric morphometrics in the discrimination of honey bee populations in Greece and the establishment of conservation areas for local honey bee populations.

  7. Does geometric morphometrics serve the needs of plasticity research?

    Indian Academy of Sciences (India)

    Katrin Schaefer; Fred L Bookstein

    2009-10-01

    The study of human craniofacial variation exemplifies general problems associated with the analysis of morphological plasticity that owe to the dependence of results on the methods by which phenotypic variation is quantified. We suggest a definition of plasticity that does not subordinate the developmental to the evolutionary: A process model in which changes are not a function of any mean or average, but only of the current state. Geometric morphometrics, a toolkit for assessing and visualizing biological form and its covariates, avoids some of the traditional pitfalls by focusing directly on the analysis of the two- and three-dimensional coordinates of anatomical landmarks. We discuss its potential relevance to phenotypic and developmental plasticity research, as well as some of its limitations, and demonstrate two useful analyses: assessment of asymmetry, and appraisal of integration. We itemize some of our previous studies on causes (inbreeding, environmental circumstances, etc.) and consequences (attractiveness perception) of asymmetry in humans, present some findings relating to the impact of sex on shape, and speculate about the adaptive relevance of one of these processes in particular. A closing argument points out that such considerations are possible only because of the careful separation of assumptions from empirical evidence entailed in the course of this type of data analysis.

  8. Geometric morphometrics as a tool for improving the comparative study of behavioural postures

    Science.gov (United States)

    Fureix, Carole; Hausberger, Martine; Seneque, Emilie; Morisset, Stéphane; Baylac, Michel; Cornette, Raphaël; Biquand, Véronique; Deleporte, Pierre

    2011-07-01

    Describing postures has always been a central concern when studying behaviour. However, attempts to compare postures objectively at phylogenetical, populational, inter- or intra-individual levels generally either rely upon a few key elements or remain highly subjective. Here, we propose a novel approach, based on well-established geometric morphometrics, to describe and to analyse postures globally (i.e. considering the animal's body posture in its entirety rather than focusing only on a few salient elements, such as head or tail position). Geometric morphometrics is concerned with describing and comparing variation and changes in the form (size and shape) of organisms using the coordinates of a series of homologous landmarks (i.e. positioned in relation to skeletal or muscular cues that are the same for different species for every variety of form and function and that have derived from a common ancestor, i.e. they have a common evolutionary ancestry, e.g. neck, wings, flipper/hand). We applied this approach to horses, using global postures (1) to characterise behaviours that correspond to different arousal levels, (2) to test potential impact of environmental changes on postures. Our application of geometric morphometrics to horse postures showed that this method can be used to characterise behavioural categories, to evaluate the impact of environmental factors (here human actions) and to compare individuals and groups. Beyond its application to horses, this promising approach could be applied to all questions involving the analysis of postures (evolution of displays, expression of emotions, stress and welfare, behavioural repertoires…) and could lead to a whole new line of research.

  9. Biometry traits and geometric morphometrics in sea bass (Dicentrarchus labrax from different farming systems

    Directory of Open Access Journals (Sweden)

    Emilio Tibaldi

    2010-01-01

    Full Text Available The effect of the farming system on biometry traits and dressing out yield were inves- tigated in market-size European sea bass (Dicentrarchus labrax cultured extensively or intensively in sea cages or land-based basins. Fish external appearences and shapes were studies with geometric morphometrics in order to assess the potential of combined methodologies in the assessment of finfish quality. Both standard biometry and geometric morphometrics were able to discriminate between sea bass farmed extensively from those cultured under intensive conditions. Geometric morphometrics has been shown to be a valuable tool for describing changes in shape features and could result a useful technique to be associated to biometry traits in the context of fish quality assessment.

  10. Geometric morphometric analysis reveals age-related differences in the distal femur of Europeans.

    Science.gov (United States)

    Cavaignac, Etienne; Savall, Frederic; Chantalat, Elodie; Faruch, Marie; Reina, Nicolas; Chiron, Philippe; Telmon, Norbert

    2017-12-01

    Few studies have looked into age-related variations in femur shape. We hypothesized that three-dimensional (3D) geometric morphometric analysis of the distal femur would reveal age-related differences. The purpose of this study was to show that differences in distal femur shape related to age could be identified, visualized, and quantified using three-dimensional (3D) geometric morphometric analysis. Geometric morphometric analysis was carried out on CT scans of the distal femur of 256 subjects living in the south of France. Ten landmarks were defined on 3D reconstructions of the distal femur. Both traditional metric and geometric morphometric analyses were carried out on these bone reconstructions. These analyses were used to identify trends in bone shape in various age-based subgroups (60). Only the average bone shape of the < 40-year subgroup was statistically different from that of the other two groups. When the population was divided into two subgroups using 40 years of age as a threshold, the subject's age was correctly assigned 80% of the time. Age-related differences are present in this bone segment. This reliable, accurate method could be used for virtual autopsy and to perform diachronic and interethnic comparisons. Moreover, this study provides updated morphometric data for a modern population in the south of France. Manufacturers of knee replacement implants will have to adapt their prosthesis models as the population evolves over time.

  11. Left Atrial trajectory impairment in Hypertrophic Cardiomyopathy disclosed by Geometric Morphometrics and Parallel Transport

    Science.gov (United States)

    Piras, Paolo; Torromeo, Concetta; Re, Federica; Evangelista, Antonietta; Gabriele, Stefano; Esposito, Giuseppe; Nardinocchi, Paola; Teresi, Luciano; Madeo, Andrea; Chialastri, Claudia; Schiariti, Michele; Varano, Valerio; Uguccioni, Massimo; Puddu, Paolo E.

    2016-10-01

    The analysis of full Left Atrium (LA) deformation and whole LA deformational trajectory in time has been poorly investigated and, to the best of our knowledge, seldom discussed in patients with Hypertrophic Cardiomyopathy. Therefore, we considered 22 patients with Hypertrophic Cardiomyopathy (HCM) and 46 healthy subjects, investigated them by three-dimensional Speckle Tracking Echocardiography, and studied the derived landmark clouds via Geometric Morphometrics with Parallel Transport. Trajectory shape and trajectory size were different in Controls versus HCM and their classification powers had high AUC (Area Under the Receiving Operator Characteristic Curve) and accuracy. The two trajectories were much different at the transition between LA conduit and booster pump functions. Full shape and deformation analyses with trajectory analysis enabled a straightforward perception of pathophysiological consequences of HCM condition on LA functioning. It might be worthwhile to apply these techniques to look for novel pathophysiological approaches that may better define atrio-ventricular interaction.

  12. Left Atrial trajectory impairment in Hypertrophic Cardiomyopathy disclosed by Geometric Morphometrics and Parallel Transport

    Science.gov (United States)

    Piras, Paolo; Torromeo, Concetta; Re, Federica; Evangelista, Antonietta; Gabriele, Stefano; Esposito, Giuseppe; Nardinocchi, Paola; Teresi, Luciano; Madeo, Andrea; Chialastri, Claudia; Schiariti, Michele; Varano, Valerio; Uguccioni, Massimo; Puddu, Paolo E.

    2016-01-01

    The analysis of full Left Atrium (LA) deformation and whole LA deformational trajectory in time has been poorly investigated and, to the best of our knowledge, seldom discussed in patients with Hypertrophic Cardiomyopathy. Therefore, we considered 22 patients with Hypertrophic Cardiomyopathy (HCM) and 46 healthy subjects, investigated them by three–dimensional Speckle Tracking Echocardiography, and studied the derived landmark clouds via Geometric Morphometrics with Parallel Transport. Trajectory shape and trajectory size were different in Controls versus HCM and their classification powers had high AUC (Area Under the Receiving Operator Characteristic Curve) and accuracy. The two trajectories were much different at the transition between LA conduit and booster pump functions. Full shape and deformation analyses with trajectory analysis enabled a straightforward perception of pathophysiological consequences of HCM condition on LA functioning. It might be worthwhile to apply these techniques to look for novel pathophysiological approaches that may better define atrio–ventricular interaction. PMID:27713503

  13. A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

    Science.gov (United States)

    Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

    2015-05-01

    Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Traditional and geometric morphometrics supporting the differentiation of two new Retracrus (Phytoptidae) species associated with heliconias.

    Science.gov (United States)

    Navia, Denise; Ferreira, Cecília B S; Reis, Aleuny C; Gondim, Manoel G C

    2015-09-01

    Cryptic diversity has been confirmed for several phytophagous mites in the Eriophyoidea superfamily previously considered as presenting low host specificity. Among generalist eriophyoids is the phytoptid Retracrus johnstoni Keifer, which has been reported in 19 palm species belonging to 11 genera, causing severe damage on some of them. Surprisingly this species was recently reported on another monocot family, Heliconiaceae, infesting Heliconia plants in Costa Rica and Brazil, being the only in the tribe Mackiellini to not be associated with palm trees. This study aimed to investigate the occurrence of cryptic species in R. johnstoni and to clarify the taxonomic status of populations associated with heliconias in the Americas. With this purpose traditional and geometric morphometric analyses were conducted as well as a detailed morphological study. Measurable trait data were analysed via univariate and multivariate analyses. Shapes of specimens from different populations were compared via geometric morphometric landmark methods. Morphometric analysis supported occurrence of at least two cryptic species previously identified as R. johsntoni and suggested occurrence of cryptic species among populations associated with different palm trees. Taxonomic descriptions of two new taxa associated with heliconias, namely Retracrus costaricensis n. sp. Ferreira and Navia and Retracrus heliconiae n. sp. Ferreira and Navia are presented. Morphometric traits that can be useful in the taxonomic identification are noted and their value is discussed. Results of the traditional morphometry and geometric methods were compared and the advantages of their joint use for Eriophyoidea systematics are discussed.

  15. The use of geometric morphometrics in understanding shape variability of sclerotized haptoral structures of monogeneans (Platyhelminthes) with insights into biogeographic variability.

    Science.gov (United States)

    Vignon, Matthias; Sasal, Pierre

    2010-06-01

    The sclerotized attachment organ of monogeneans has been widely used to address fundamental questions in ecology and evolution. However, traditional morphometric techniques appear to be partially inadequate and non-optimal. Traditional linear measurements mainly provide information on the size of sclerites but provide very little information, if any, on their shape. The shape of sclerites is indeed virtually unexplored and its implication for ecological and evolutionary processes remains to be analyzed. This study aims to both introduce and illustrate the use of geometric morphometrics in order to study sclerites of monogeneans in a biogeographic context. To do this, we investigated morphological variation patterns among four populations from the Pacific Ocean and six monogenean species through traditional and geometric morphometric techniques. Unlike the traditional method, the geometric morphometric method yielded a high percentage of individuals correctly classified to the four populations, providing strong evidence for phenotypic variability, divergence and local adaptation among islands without evolutionary constraint. Moreover, the traditional method also resulted in inconsistent interpretations of shape variations. This study highlighted the limitations that may arise when using traditional morphometric techniques and emphasizes that considerable information about the shape of sclerotized haptoral parts is added by using geometric morphometrics. Given the prominent taxonomic, ecological and evolutionary role of the haptor for characterizing monogeneans, we ultimately discuss the potential broad use of geometric morphometrics in a wide variety of ecological and evolutionary contexts. This powerful approach might allow a more robust estimation of the extent to which traditional evolutionary theories based on size of sclerites are congruent with their shape.

  16. Inferring palaeoecology in extinct tremarctine bears (Carnivora, Ursidae) using geometric morphometrics

    OpenAIRE

    Figueirido, Borja; Soibelzon, Leopoldo Héctor

    2009-01-01

    In this study we explore the ecomorphological patterns of extinct tremarctine bears in South America during the Great American Biotic Interchange (GABI). These patterns are used to derive palaeoautoecological inferences in extinct tremarctines and their palaeosinecological relationships within Plio-Pleistocene ecosystems. We used geometric morphometrics of landmark data to recover the shape of the craniomandibular skeleton of bears. The results reveal different ecomorphological specialization...

  17. Geometrical approach to fluid models

    NARCIS (Netherlands)

    Kuvshinov, B. N.; Schep, T. J.

    1997-01-01

    Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical

  18. Geometrical approach to fluid models

    NARCIS (Netherlands)

    Kuvshinov, B. N.; Schep, T. J.

    1997-01-01

    Differential geometry based upon the Cartan calculus of differential forms is applied to investigate invariant properties of equations that describe the motion of continuous media. The main feature of this approach is that physical quantities are treated as geometrical objects. The geometrical notio

  19. Three-dimensional geometric morphometric analysis reveals ethnic dimorphism in the shape of the femur.

    Science.gov (United States)

    Cavaignac, Etienne; Li, Ke; Faruch, Marie; Savall, Frederic; Chiron, Philippe; Huang, W; Telmon, Norbert

    2017-12-01

    Ethnic dimorphism in the distal femur has never been studied in a three-dimensional analysis focused on shape instead of size. Yet, this dimorphism has direct implications in orthopedic surgery and in anthropology. The goal of this study was to show that differences in distal femur shape related to ethnic dimorphism could be identified, visualized, and quantified using 3D geometric morphometric analysis. CT scans of the distal femur were taken from 482 patients who were free of any bone-related pathology: 240 patients were European (E) and 242 were Asian (A). Ten osteometric landmarks based on standard bone landmarks used in anthropometry were placed on these scans. Geometric morphometric analysis, principal component analysis (PCA), canonical variates analysis (CVA), and other discriminant analyses (Goodall's F-test and Mahalanobis distance) were performed. A cross-validation analysis was carried out to determine the percentage of cases in which the ethnicity was correctly estimated. The shape of the E and A distal femur differed significantly (Goodall's F = 94.43, P geometric morphometric analysis made it possible to demonstrate these differences. The large number of subjects studied has helped modernize the references for certain bone measurements, with direct implication for orthopedic surgery and anthropology.

  20. A new species of Falsopodabrus Pic characterized with geometric morphometrics (Coleoptera, Cantharidae).

    Science.gov (United States)

    Li, Limei; Qi, Yaqing; Yang, Yuxia; Bai, Ming

    2016-01-01

    A new species of Falsopodabrus Pic, 1927 is described, Falsopodabrus tridentatus Yang, sp. n. (Yunnan, China). Geometric morphometric analyses based on the shapes of pronotum and hind wing and comparisons with two sibling species, Falsopodabrus himalaicus Wittmer, 1974 and Falsopodabrus martensi (Wittmer, 1979), support the valid status of the new species, also confirmed by the characters of tarsal claws. In addition to Falsopodabrus himalaicus and Falsopodabrus martensi, Falsopodabrus kostali Švihla, 2004 and Falsopodabrus rolciki Švihla, 2004 are recorded from China for the first time.

  1. A geometric morphometric analysis of cranial and mandibular shape variation of didelphid marsupials

    Directory of Open Access Journals (Sweden)

    D. Astúa de Moraes

    2000-06-01

    Full Text Available Abstract The New World marsupial family Didelphidae is one of the oldest among mammals and is usually regarded as a morphologically conservative group. We analyzed cranial shape variation among six species of the six largest living genera of the family using two-dimensional landmark data. We captured and digitized video images of the skull and mandible for the following species: Caluromys philander (n = 65, Chironectes minimus (n = 30, Didelphis aurita (n = 70, Lutreolina crassicaudata (n = 37, Metachirus nudicaudatus (n = 77 and Philander frenata (n = 62. Fourteen landmarks were defined for the lateral, 25 for the ventral, 23 for the dorsal views of the skull, and nine on the mandibular lateral view. Sex, species, and interaction effects were analyzed with a two-way MANOVA on the matrices of coordinates aligned by general least squares. All four views had significant interactions. Canonical Variates Analysis was performed on sexes and species, and shape was regressed on the canonical variate scores for each species. Caluromys philander was clearly the most distinct species, with paedomorphic features that can be related to its arboreal habits. A conspicuous shortening of the rostrum distinguishes the highly carnivorous Lutreolina crassicaudata. Didelphis aurita and Philander frenata overlapped somewhat, reflecting shape similarities associated with their phylogenetic affinities, while the few differences observed are probably allometric consequences of size differences. Philander frenata and Chironectes minimus showed similar cranial shapes, while Metachirus nudicaudatus was distinctive with a broad and elongated rostrum. In spite of an overall similar shape, the geometric morphometric approach revealed several marked differences among species that can be related to their phylogenetic origin and their adaptive

  2. BMI and WHR Are Reflected in Female Facial Shape and Texture: A Geometric Morphometric Image Analysis

    Science.gov (United States)

    Mayer, Christine; Windhager, Sonja; Schaefer, Katrin; Mitteroecker, Philipp

    2017-01-01

    Facial markers of body composition are frequently studied in evolutionary psychology and are important in computational and forensic face recognition. We assessed the association of body mass index (BMI) and waist-to-hip ratio (WHR) with facial shape and texture (color pattern) in a sample of young Middle European women by a combination of geometric morphometrics and image analysis. Faces of women with high BMI had a wider and rounder facial outline relative to the size of the eyes and lips, and relatively lower eyebrows. Furthermore, women with high BMI had a brighter and more reddish skin color than women with lower BMI. The same facial features were associated with WHR, even though BMI and WHR were only moderately correlated. Yet BMI was better predictable than WHR from facial attributes. After leave-one-out cross-validation, we were able to predict 25% of variation in BMI and 10% of variation in WHR by facial shape. Facial texture predicted only about 3–10% of variation in BMI and WHR. This indicates that facial shape primarily reflects total fat proportion, rather than the distribution of fat within the body. The association of reddish facial texture in high-BMI women may be mediated by increased blood pressure and superficial blood flow as well as diet. Our study elucidates how geometric morphometric image analysis serves to quantify the effect of biological factors such as BMI and WHR to facial shape and color, which in turn contributes to social perception. PMID:28052103

  3. Applications of geometric morphometric analysis in describing sexual dimorphism in shell shapes in Vivipara angularis Muller (Family Viviparidae

    Directory of Open Access Journals (Sweden)

    Carlo Stephen O. Moneva

    2012-06-01

    Full Text Available Prior studies have shown different insights about sexual shell dimorphism in the snails of family Viviparidae. This study was conductedto evaluate and determine the occurence of sexual dimorphism and shape variation in the shells of the viviparid snail, Vivipara angularisMuller, from three characters (ventral/aperture, dorsal, and top/whorl using geometric morphometric analyses. All the three shell charactersexhibited significant sexual shell dimorphism, this may be due to adaptations for brooding of the viviparid snails. Results indicate employmentof different shell characters subjected to geometric morphometric analysis other than the aperture, in order to discriminate between sexes ofthe snails accurately.

  4. Ancestry Estimation in Forensic Anthropology: Geometric Morphometric versus Standard and Nonstandard Interlandmark Distances.

    Science.gov (United States)

    Katherine Spradley, M; Jantz, Richard L

    2016-07-01

    Standard cranial measurements are commonly used for ancestry estimation; however, 3D digitizers have made cranial landmark data collection and geometric morphometric (GM) analyses more popular within forensic anthropology. Yet there has been little focus on which data type works best. The goal of the present research is to test the discrimination ability of standard and nonstandard craniometric measurements and data derived from GM analysis. A total of 31 cranial landmarks were used to generate 465 interlandmark distances, including a subset of 20 commonly used measurements, and to generate principal component scores from procrustes coordinates. All were subjected to discriminant function analysis to ascertain which type of data performed best for ancestry estimation of American Black and White and Hispanic males and females. The nonstandard interlandmark distances generated the highest classification rates for females (90.5%) and males (88.2%). Using nonstandard interlandmark distances over more commonly used measurements leads to better ancestry estimates for our current population structure.

  5. Landmark-based geometric morphometric analysis of wing shape among certain species of Aedes mosquitoes in District Dehradun (Uttarakhand, India

    Directory of Open Access Journals (Sweden)

    Ritwik Mondal

    2015-01-01

    Interpretation & conclusion: It has been marked out that the geometric morphometrics utilizes powerful and comprehensive statistical procedures to analyze the shape differences of a morphological feature, assuming that the studied mosquitoes may represent different genotypes and probably come from one diverse gene pool.

  6. Femoral curvature in Neanderthals and modern humans: a 3D geometric morphometric analysis.

    Science.gov (United States)

    De Groote, Isabelle

    2011-05-01

    Since their discovery, Neanderthals have been described as having a marked degree of anteroposterior curvature of the femoral shaft. Although initially believed to be pathological, subsequent discoveries of Neanderthal remains lead femoral curvature to be considered as a derived Neanderthal feature. A recent study on Neanderthals and middle and early Upper Palaeolithic modern humans found no differences in femoral curvature, but did not consider size-corrected curvature. Therefore, the objectives of this study were to use 3D morphometric landmark and semi-landmark analysis to quantify relative femoral curvature in Neanderthals, Upper Palaeolithic and recent modern humans, and to compare adult bone curvature as part of the overall femoral morphology among these populations. Comparisons among populations were made using geometric morphometrics (3D landmarks) and standard multivariate methods. Comparative material involved all available complete femora from Neanderthal and Upper Palaeolithic modern human, archaeological (Mesolithic, Neolithic, Medieval) and recent human populations representing a wide geographical and lifestyle range. There are significant differences in the anatomy of the femur between Neanderthals and modern humans. Neanderthals have more curved femora than modern humans. Early modern humans are most similar to recent modern humans in their anatomy. Femoral curvature is a good indicator of activity level and habitual loading of the lower limb, indicating higher activity levels in Neanderthals than modern humans. These differences contradict robusticity studies and the archaeological record, and would suggest that femoral morphology, and curvature in particular, in Neanderthals may not be explained by adult behavior alone and could be the result of genetic drift, natural selection or differences in behavior during ontogeny.

  7. Metric and geometric morphometric analysis of new hominin fossils from Maba (Guangdong, China).

    Science.gov (United States)

    Xiao, Dongfang; Bae, Christopher J; Shen, Guanjun; Delson, Eric; Jin, Jennie J H; Webb, Nicole M; Qiu, Licheng

    2014-09-01

    We present an analysis of a set of previously unreported hominin fossils from Maba (Guangdong, China), a cave site that is best known for the presence of a partial hominin cranium currently assigned as mid-Pleistocene Homo and that has been traditionally dated to around the Middle-Late Pleistocene transition. A more recent set of Uranium series dates indicate that the Maba travertine may date to >237 ka (thousands of years ago), as opposed to the original U-series date, which placed Maba at 135-129 ka. The fossils under study include five upper first and second molars and a partial left mandible with a socketed m3, all recovered from different parts of the site than the cranium or the dated sediments. The results of our metric and 2D geometric morphometric ('GM') study suggest that the upper first molars are likely from modern humans, suggesting a more recent origin. The upper second molars align more closely with modern humans, though the minimum spanning tree from the 2D GM analysis also connects Maba to Homo neanderthalensis. The patterning in the M2s is not as clear as with the M1s. The m3 and partial mandible are morphometrically intermediate between Holocene modern humans and older Homo sapiens. However, a minimum spanning tree indicates that both the partial mandible and m3 align most closely with Holocene modern humans, and they also may be substantially younger than the cranium. Because questions exist regarding the context and the relationship of the dated travertine with the hominin fossils, we suggest caution is warranted in interpreting the Maba specimens.

  8. Heritability of face shape in twins: a preliminary study using 3D stereophotogrammetry and geometric morphometrics

    Directory of Open Access Journals (Sweden)

    Seth M. Weinberg

    2013-11-01

    Full Text Available Introduction: Previous research suggests that aspects of facial surface morphology are heritable.  Traditionally, heritability studies have used a limited set of linear distances to quantify facial morphology and often employ statistical methods poorly designed to deal with biological shape.  In this preliminary report, we use a combination of 3D photogrammetry and landmark-based morphometrics to explore which aspects of face shape show the strongest evidence of heritability in a sample of twins. Methods: 3D surface images were obtained from 21 twin pairs (10 monozygotic, 11 same-sex dizygotic.  Thirteen 3D landmarks were collected from each facial surface and their coordinates subjected to geometric morphometric analysis.  This involved superimposing the individual landmark configurations and then subjecting the resulting shape coordinates to a principal components analysis.  The resulting PC scores were then used to calculate rough narrow-sense heritability estimates. Results: Three principal components displayed evidence of moderate to high heritability and were associated with variation in the breadth of orbital and nasal structures, upper lip height and projection, and the vertical and forward projection of the root of the nose due to variation in the position of nasion. Conclusions: Aspects of facial shape, primarily related to variation in length and breadth of central midfacial structures, were shown to demonstrate evidence of strong heritability. An improved understanding of which facial features are under strong genetic control is an important step in the identification of specific genes that underlie normal facial variation.

  9. Comparison of morphological variations among three species of the genus Paracobitis in Iran using geometric morphometrics method with a taxonomical review on the genus in Iran

    Directory of Open Access Journals (Sweden)

    Omid Jafari

    2015-04-01

    Full Text Available This study was conducted to apply the landmark-based geometric morphometrics technique to differentiate three species of the genus Paracobitis (P. iranica, P. malapterura and P. rhadinaeus in Iran based on their body shape, because previous works, using traditional morphometrics, could not distinct them. A total of 150 specimens were sampled from the Zaringol, Madarsoo, Ghomrood, Kordan Rivers and Chahnimeh reservoir. The left side of the specimens was photographed using a digital camera and then fifteen landmark-points were digitized on two-dimensional images using TpsDig2. Landmark data were analyzed after a generalised procrustes analysis using PCA, CVA and cluster analysis. The patterns of body shape differences among the populations were illustrated in the deformation grids in relation to consensus configuration. The results showed a significant differences among the studied species and their populations in terms of morphological traits (P<0.0001. Some differences were found in the length and depth of head, depth of body, caudal peduncle length and position of eye and position of dorsal fin. The result also showed that P. iranica from Kordan River can be considered to be a distinct taxon compared to the Ghomrood taxon based on its morphological characteristics. In addition, our findings revealed that the geometric morphometrics approach can be a proper tool for morphological and taxonomic studies in species with small sizes including Nemachelinae.

  10. Wing geometric morphometrics and molecular assessment of members in the Albitarsis Complex from Colombia.

    Science.gov (United States)

    Gómez, G; Jaramillo, L; Correa, M M

    2013-11-01

    Malaria parasites are transmitted to humans by female mosquitoes of the genus Anopheles. The Albitarsis Complex harbours at least eight species not readily differentiable by morphology. This complicates the determination of those species involved in malaria transmission and the implementation of targeted and effective vector control strategies. In Colombia, there is little information about the identity and distribution of the Albitarsis Complex members. In this work, COI DNA barcoding was used to assign specimens Anopheles albitarsis s.l. to any of the previously designated species of the Albitarsis Complex. Two molecular operational taxonomic units (MOTUs), differentially distributed in Colombia, were detected, A. albitarsis I in the NW and NE, and A. albitarsis F, E and NE Colombia. In contrast, nuclear white gene and ITS2 sequence analyses did not allow differentiating between the MOTUs. Wing landmark-based geometric morphometrics applied to explore intertaxa phenotypic heterogeneity showed a subtle but significant difference in size, while shape did not allow the separation of the MOTUs. In general, the multiple marker analysis was not supportive of the existence in Colombia of more than one species of the Albitarsis Complex.

  11. Estimation of pediatric skeletal age using geometric morphometrics and three-dimensional cranial size changes.

    Science.gov (United States)

    Braga, José; Treil, Jacques

    2007-11-01

    This paper presents a method for estimating the skeletal age of children based on the centroid size of their face and their basicranium, derived from the three-dimensional coordinates of anatomical landmarks. The sample consists of computed tomography scans of 127 children (54 boys, 73 girls) of mixed origin living in the area of Toulouse (France), ranging in age from a few days to 18 years. The purpose of the present investigation was, first, to increase the variety of age-related structures theoretically available for pediatric skeletal age estimation and, second, to devise a method that can be applicable from early postnatal age to the end of adolescence with a satisfactory accuracy independent of age and even a better accuracy with greater age. We examined the relationship between the chronological age and the centroid size, calculated by using geometric morphometric methods and a linear model. With the aid of cross-validations, the statistical analysis indicates that the centroid size of the facial skeleton can be used an age-related variable without any loss of accuracy with increased age, contrary to most of the methods of pediatric age estimation. The standard error was always lower or equal to 2.1 years (at the 95% confidence level) and decreased in our sub-sample of older children represented by a larger number of individuals.

  12. Quantitative analysis of Neanderthal temporal bone morphology using three-dimensional geometric morphometrics.

    Science.gov (United States)

    Harvati, Katerina

    2003-04-01

    The temporal bone is the location of several traits thought to differentiate Neanderthals from modern humans, including some proposed Neanderthal-derived traits. Most of these, however, are difficult to measure and are usually described qualitatively. This study applied the techniques of geometric morphometrics to the complex morphology of the temporal bone, in order to quantify the differences observed between Neanderthal and modern human anatomy. Two hundred and seventy modern human crania were measured, representing 9 populations of 30 individuals each, and spanning the extremes of the modern human geographical range. Twelve Neanderthal specimens, as well as Reilingen, Kabwe, Skhul 5, Qafzeh 9, and 4 Late Paleolithic European specimens, were included in the fossil sample. The data were collected in the form of three-dimensional (3-D) landmark coordinates, and specimen configurations were superimposed using generalized Procrustes analysis. The fitted coordinates were then analyzed by an array of multivariate statistical methods, including principal components analysis, canonical variates analysis, and Mahalanobis D(2). The temporal bone landmark analysis was very successful in separating Neanderthals from modern humans. Neanderthals were separated from modern humans in both the principal components and canonical variates analyses. They were much further in Mahalanobis distances from all modern human populations than any two modern human groups were from each other. Most of the previously described temporal bone traits contributed to this separation. Copyright 2003 Wiley-Liss, Inc.

  13. Facial orientation and facial shape in extant great apes: a geometric morphometric analysis of covariation.

    Directory of Open Access Journals (Sweden)

    Dimitri Neaux

    Full Text Available The organization of the bony face is complex, its morphology being influenced in part by the rest of the cranium. Characterizing the facial morphological variation and craniofacial covariation patterns in extant hominids is fundamental to the understanding of their evolutionary history. Numerous studies on hominid facial shape have proposed hypotheses concerning the relationship between the anterior facial shape, facial block orientation and basicranial flexion. In this study we test these hypotheses in a sample of adult specimens belonging to three extant hominid genera (Homo, Pan and Gorilla. Intraspecific variation and covariation patterns are analyzed using geometric morphometric methods and multivariate statistics, such as partial least squared on three-dimensional landmarks coordinates. Our results indicate significant intraspecific covariation between facial shape, facial block orientation and basicranial flexion. Hominids share similar characteristics in the relationship between anterior facial shape and facial block orientation. Modern humans exhibit a specific pattern in the covariation between anterior facial shape and basicranial flexion. This peculiar feature underscores the role of modern humans' highly-flexed basicranium in the overall integration of the cranium. Furthermore, our results are consistent with the hypothesis of a relationship between the reduction of the value of the cranial base angle and a downward rotation of the facial block in modern humans, and to a lesser extent in chimpanzees.

  14. A geometric morphometric analysis of hominin upper premolars. Shape variation and morphological integration.

    Science.gov (United States)

    Gómez-Robles, Aida; Martinón-Torres, María; Bermúdez de Castro, José María; Prado-Simón, Leyre; Arsuaga, Juan Luis

    2011-12-01

    This paper continues the series of articles initiated in 2006 that analyse hominin dental crown morphology by means of geometric morphometric techniques. The detailed study of both upper premolar occlusal morphologies in a comprehensive sample of hominin fossils, including those coming from the Gran Dolina-TD6 and Sima de los Huesos sites from Atapuerca, Spain, complement previous works on lower first and second premolars and upper first molars. A morphological gradient consisting of the change from asymmetric to symmetric upper premolars and a marked reduction of the lingual cusp in recent Homo species has been observed in both premolars. Although percentages of correct classification based on upper premolar morphologies are not very high, significant morphological differences between Neanderthals (and European middle Pleistocene fossils) and modern humans have been identified, especially in upper second premolars. The study of morphological integration between premolar morphologies reveals significant correlations that are weaker between upper premolars than between lower ones and significant correlations between antagonists. These results have important implications for understanding the genetic and functional factors underlying dental phenotypic variation and covariation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Pectoral fin morphology of batoid fishes (Chondrichthyes: Batoidea): explaining phylogenetic variation with geometric morphometrics.

    Science.gov (United States)

    Franklin, Oliver; Palmer, Colin; Dyke, Gareth

    2014-10-01

    The diverse cartilaginous fish lineage, Batoidea (rays, skates, and allies), sister taxon to sharks, comprises a huge range of morphological diversity which to date remains unquantified and unexplained in terms of evolution or locomotor style. A recent molecular phylogeny has enabled us to confidently assess broadscale aspects of morphology across Batoidea. Geometric morphometrics quantifies the major aspects of shape variation, focusing on the enlarged pectoral fins which characterize batoids, to explore relationships between ancestry, locomotion and habitat. A database of 253 specimens, encompassing 60 of the 72 batoid genera, reveals that the majority of morphological variation across Batoidea is attributable to fin aspect-ratio and the chordwise location of fin apexes. Both aspect-ratio and apex location exhibit significant phylogenetic signal. Standardized independent linear contrast analysis reveals that fin aspect-ratio can predict locomotor style. This study provides the first evidence that low aspect-ratio fins are correlated with undulatory-style locomotion in batoids, whereas high aspect-ratio fins are correlated with oscillatory locomotion. We also show that it is phylogeny that determines locomotor style. In addition, body- and caudal fin-locomotors are shown to exhibit low aspect-ratio fins, whereas a pelagic lifestyle correlates with high aspect-ratio fins. These results emphasize the importance of phylogeny in determining batoid pectoral fin shape, however, interactions with other constraints, most notably locomotor style, are also highlighted as significant. © 2014 Wiley Periodicals, Inc.

  16. The evolution of cranial form and function in theropod dinosaurs: insights from geometric morphometrics.

    Science.gov (United States)

    Brusatte, S L; Sakamoto, M; Montanari, S; Harcourt Smith, W E H

    2012-02-01

    Theropod dinosaurs, an iconic clade of fossil species including Tyrannosaurus and Velociraptor, developed a great diversity of body size, skull form and feeding habits over their 160+ million year evolutionary history. Here, we utilize geometric morphometrics to study broad patterns in theropod skull shape variation and compare the distribution of taxa in cranial morphospace (form) to both phylogeny and quantitative metrics of biting behaviour (function). We find that theropod skulls primarily differ in relative anteroposterior length and snout depth and to a lesser extent in orbit size and depth of the cheek region, and oviraptorosaurs deviate most strongly from the "typical" and ancestral theropod morphologies. Noncarnivorous taxa generally fall out in distinct regions of morphospace and exhibit greater overall disparity than carnivorous taxa, whereas large-bodied carnivores independently converge on the same region of morphospace. The distribution of taxa in morphospace is strongly correlated with phylogeny but only weakly correlated with functional biting behaviour. These results imply that phylogeny, not biting function, was the major determinant of theropod skull shape.

  17. Homo floresiensis contextualized: a geometric morphometric comparative analysis of fossil and pathological human samples.

    Directory of Open Access Journals (Sweden)

    Karen L Baab

    Full Text Available The origin of hominins found on the remote Indonesian island of Flores remains highly contentious. These specimens may represent a new hominin species, Homo floresiensis, descended from a local population of Homo erectus or from an earlier (pre-H. erectus migration of a small-bodied and small-brained hominin out of Africa. Alternatively, some workers suggest that some or all of the specimens recovered from Liang Bua are pathological members of a small-bodied modern human population. Pathological conditions proposed to explain their documented anatomical features include microcephaly, myxoedematous endemic hypothyroidism ("cretinism" and Laron syndrome (primary growth hormone insensitivity. This study evaluates evolutionary and pathological hypotheses through comparative analysis of cranial morphology. Geometric morphometric analyses of landmark data show that the sole Flores cranium (LB1 is clearly distinct from healthy modern humans and from those exhibiting hypothyroidism and Laron syndrome. Modern human microcephalic specimens converge, to some extent, on crania of extinct species of Homo. However in the features that distinguish these two groups, LB1 consistently groups with fossil hominins and is most similar to H. erectus. Our study provides further support for recognizing the Flores hominins as a distinct species, H. floresiensis, whose affinities lie with archaic Homo.

  18. Homo floresiensis contextualized: a geometric morphometric comparative analysis of fossil and pathological human samples.

    Science.gov (United States)

    Baab, Karen L; McNulty, Kieran P; Harvati, Katerina

    2013-01-01

    The origin of hominins found on the remote Indonesian island of Flores remains highly contentious. These specimens may represent a new hominin species, Homo floresiensis, descended from a local population of Homo erectus or from an earlier (pre-H. erectus) migration of a small-bodied and small-brained hominin out of Africa. Alternatively, some workers suggest that some or all of the specimens recovered from Liang Bua are pathological members of a small-bodied modern human population. Pathological conditions proposed to explain their documented anatomical features include microcephaly, myxoedematous endemic hypothyroidism ("cretinism") and Laron syndrome (primary growth hormone insensitivity). This study evaluates evolutionary and pathological hypotheses through comparative analysis of cranial morphology. Geometric morphometric analyses of landmark data show that the sole Flores cranium (LB1) is clearly distinct from healthy modern humans and from those exhibiting hypothyroidism and Laron syndrome. Modern human microcephalic specimens converge, to some extent, on crania of extinct species of Homo. However in the features that distinguish these two groups, LB1 consistently groups with fossil hominins and is most similar to H. erectus. Our study provides further support for recognizing the Flores hominins as a distinct species, H. floresiensis, whose affinities lie with archaic Homo.

  19. A Geometric Approach to Noncommutative Principal Bundles

    CERN Document Server

    Wagner, Stefan

    2011-01-01

    From a geometrical point of view it is, so far, not sufficiently well understood what should be a "noncommutative principal bundle". Still, there is a well-developed abstract algebraic approach using the theory of Hopf algebras. An important handicap of this approach is the ignorance of topological and geometrical aspects. The aim of this thesis is to develop a geometrically oriented approach to the noncommutative geometry of principal bundles based on dynamical systems and the representation theory of the corresponding transformation group.

  20. Finite element modelling of squirrel, guinea pig and rat skulls: using geometric morphometrics to assess sensitivity.

    Science.gov (United States)

    Cox, P G; Fagan, M J; Rayfield, E J; Jeffery, N

    2011-12-01

    Rodents are defined by a uniquely specialized dentition and a highly complex arrangement of jaw-closing muscles. Finite element analysis (FEA) is an ideal technique to investigate the biomechanical implications of these specializations, but it is essential to understand fully the degree of influence of the different input parameters of the FE model to have confidence in the model's predictions. This study evaluates the sensitivity of FE models of rodent crania to elastic properties of the materials, loading direction, and the location and orientation of the models' constraints. Three FE models were constructed of squirrel, guinea pig and rat skulls. Each was loaded to simulate biting on the incisors, and the first and the third molars, with the angle of the incisal bite varied over a range of 45°. The Young's moduli of the bone and teeth components were varied between limits defined by findings from our own and previously published tests of material properties. Geometric morphometrics (GMM) was used to analyse the resulting skull deformations. Bone stiffness was found to have the strongest influence on the results in all three rodents, followed by bite position, and then bite angle and muscle orientation. Tooth material properties were shown to have little effect on the deformation of the skull. The effect of bite position varied between species, with the mesiodistal position of the biting tooth being most important in squirrels and guinea pigs, whereas bilateral vs. unilateral biting had the greatest influence in rats. A GMM analysis of isolated incisor deformations showed that, for all rodents, bite angle is the most important parameter, followed by elastic properties of the tooth. The results here elucidate which input parameters are most important when defining the FE models, but also provide interesting glimpses of the biomechanical differences between the three skulls, which will be fully explored in future publications. © 2011 The Authors. Journal of

  1. Ecological character displacement in Plethodon: biomechanical differences found from a geometric morphometric study.

    Science.gov (United States)

    Adams, D C; Rohlf, F J

    2000-04-11

    Ecological character displacement describes a pattern where morphological differences between sympatric species are enhanced through interspecific competition. Although widely considered a pervasive force in evolutionary ecology, few clear-cut examples have been documented. Here we report a case of ecological character displacement between two salamander species, Plethodon cinereus and Plethodon hoffmani. Morphology was quantified by using linear measurements and landmark-based geometric morphometric methods for specimens from allopatric and sympatric populations from two geographic transects in south-central Pennsylvania, and stomach contents were assayed to quantify food resource use. Morphological variation was also assessed in 13 additional allopatric populations. In both transects, we found significant morphological differentiation between sympatric populations that was associated with a reduction in prey consumption in sympatry and a segregation of prey according to prey size. No trophic morphological or resource use differences were found between allopatric populations, and comparisons of sympatric populations with randomly paired allopatric populations revealed that the observed sympatric morphological differentiation was greater than expected by chance. The major trophic anatomical differences between sympatric populations relates to functional and biomechanical differences in jaw closure: sympatric P. hoffmani have a faster closing jaw, whereas sympatric P. cinereus have a slower, stronger jaw. Because salamanders immobilize prey of different sizes in different ways, and because the observed sympatric biomechanical differences in jaw closure are associated with the differences in prey consumption, the observed character displacement has a functional ecological correlate, and we can link changes in form with changes in function in this apparent example of character displacement.

  2. Beyond bilateral symmetry: geometric morphometric methods for any type of symmetry

    Directory of Open Access Journals (Sweden)

    Klingenberg Christian

    2011-09-01

    Full Text Available Abstract Background Studies of symmetric structures have made important contributions to evolutionary biology, for example, by using fluctuating asymmetry as a measure of developmental instability or for investigating the mechanisms of morphological integration. Most analyses of symmetry and asymmetry have focused on organisms or parts with bilateral symmetry. This is not the only type of symmetry in biological shapes, however, because a multitude of other types of symmetry exists in plants and animals. For instance, some organisms have two axes of reflection symmetry (biradial symmetry; e.g. many algae, corals and flowers or rotational symmetry (e.g. sea urchins and many flowers. So far, there is no general method for the shape analysis of these types of symmetry. Results We generalize the morphometric methods currently used for the shape analysis of bilaterally symmetric objects so that they can be used for analyzing any type of symmetry. Our framework uses a mathematical definition of symmetry based on the theory of symmetry groups. This approach can be used to divide shape variation into a component of symmetric variation among individuals and one or more components of asymmetry. We illustrate this approach with data from a colonial coral that has ambiguous symmetry and thus can be analyzed in multiple ways. Our results demonstrate that asymmetric variation predominates in this dataset and that its amount depends on the type of symmetry considered in the analysis. Conclusions The framework for analyzing symmetry and asymmetry is suitable for studying structures with any type of symmetry in two or three dimensions. Studies of complex symmetries are promising for many contexts in evolutionary biology, such as fluctuating asymmetry, because these structures can potentially provide more information than structures with bilateral symmetry.

  3. Linear and geometric morphometric analysis of long bone scaling patterns in Jurassic neosauropod dinosaurs: their functional and paleobiological implications.

    Science.gov (United States)

    Bonnan, Matthew F

    2007-09-01

    Neosauropod dinosaurs were gigantic, herbivorous dinosaurs. Given that the limb skeleton is essentially a plastic, mobile framework that supports and moves the body, analysis of long bone scaling can reveal limb adaptations that supported neosauropod gigantism. Previously, analyses of linear dimensions have revealed a relatively isometric scaling pattern for the humerus and femur of neosauropods. Here, a combined scaling analysis of humerus and femur linear dimensions, cortical area, and shape across six neosauropod taxa is used to test the hypothesis that neosauropod long bones scaled isometrically and to investigate the paleobiological implications of these trends. A combination of linear regression and geometric morphometrics analyses of neosauropod humeri and femora were performed using traditional and thin-plate splines approaches. The neosauropod sample was very homogeneous, and linear analyses revealed that nearly all humerus and femur dimensions, including cortical area, scale with isometry against maximum length. Thin-plate splines analyses showed that little to no significant shape change occurs with increasing length or cortical area for the humerus or femur. Even with the exclusion of the long-limbed Brachiosaurus, the overall trends were consistently isometric. These results suggest that the mechanical advantage of limb-moving muscles and the relative range of limb movement decreased with increasing size. The isometric signal for neosauropod long bone dimensions and shape suggests these dinosaurs may have reached the upper limit of vertebrate long bone mechanics. Perhaps, like stilt-walkers, the absolutely long limbs of the largest neosauropods allowed for efficient locomotion at gigantic size with few ontogenetic changes.

  4. Elemental microchemistry, fatty acid profile and geometric morphometrics signatures of goose barnacles (Pollicipes pollicipes reveal their place of origin

    Directory of Open Access Journals (Sweden)

    Rui Albuquerque

    2014-06-01

    Full Text Available Seafood plays an important role in the socioeconomic, gastronomy and cultural heritage of Portuguese coastal communities. In the Iberian Peninsula, the goose barnacle Pollicipes pollicipes is the intertidal biological resource most heavily exploited by man, resulting on overexploitation of stocks. In the MPA of BNR P.pollicipes harvesting is however strictly regulated, making it a good example of marine resources management. Analytical methods able to identify the origin of goose barnacle would be an important tool to help the management of the trade. For such purpose, we investigated whether P. pollicipes have site-specific differences based on its elemental microchemistry (EM, fatty acid profile (FA and capitulum shape (CS. The analysis was performed on specimens collected from 3 sites in the BNR and 7 along a 300 km stretch of the Portuguese coast. For each individual we analysed the largest lateral shell for EM using ICP-MS, the FA content of the muscle using GC-FID, and the CS using geometric morphometrics. Discriminant function analyses (DFA for both EM and FA separately provided a high reclassification success (77.6% and 99% respectively, of cross-validated cases correctly classified, while for EM combined with FA allowed for a 100% reclassification success. DFA analysis based only on CS, revealed a low classification success (29.6%. These results show that EM and FA signatures can be a powerful tool to infer goose barnacles origin. Such “fingerprinting” approach can be used to track and identify goose barnacles origin, helping in establishing an origin certificate and increasing the potential value of biological resources from Portuguese MPAs.

  5. Geometric morphometrics: a method for Rainbow trout stocks identification in aquaculture

    OpenAIRE

    F. FACCENDA; Bozzi, R.; Parisi, G; F. LUNELLI

    2011-01-01

    Stock identification is an interdisciplinary field that involves the recognition of self-sustaining components within populations and is a central theme in fisheries science and management. Characters used to identify fish stocks can be divided into three groups: those that are purely genetic, those that are purely environmental, and those that may reflect both genetic and environmental variation. Body shape is a difficult, but important, trait to quantify. Morphometric analysis provides a po...

  6. Anthropological facial approximation in three dimensions (AFA3D): computer-assisted estimation of the facial morphology using geometric morphometrics.

    Science.gov (United States)

    Guyomarc'h, Pierre; Dutailly, Bruno; Charton, Jérôme; Santos, Frédéric; Desbarats, Pascal; Coqueugniot, Hélène

    2014-11-01

    This study presents Anthropological Facial Approximation in Three Dimensions (AFA3D), a new computerized method for estimating face shape based on computed tomography (CT) scans of 500 French individuals. Facial soft tissue depths are estimated based on age, sex, corpulence, and craniometrics, and projected using reference planes to obtain the global facial appearance. Position and shape of the eyes, nose, mouth, and ears are inferred from cranial landmarks through geometric morphometrics. The 100 estimated cutaneous landmarks are then used to warp a generic face to the target facial approximation. A validation by re-sampling on a subsample demonstrated an average accuracy of c. 4 mm for the overall face. The resulting approximation is an objective probable facial shape, but is also synthetic (i.e., without texture), and therefore needs to be enhanced artistically prior to its use in forensic cases. AFA3D, integrated in the TIVMI software, is available freely for further testing.

  7. The Minimal Geometric Deformation Approach Extended

    CERN Document Server

    Casadio, Roberto; da Rocha, Roldao

    2015-01-01

    The minimal geometric deformation approach was introduced in order to study the exterior space-time around spherically symmetric self-gravitating systems, like stars or similar astrophysical objects as well, in the Randall-Sundrum brane-world framework. A consistent extension of this approach is developed here, which contains modifications of both the time component and the radial component of a spherically symmetric metric. A modified Schwarzschild geometry is obtained as an example of its simplest application.

  8. Artificial neural networks and geometric morphometric methods as a means for classification: A case-study using teeth from Carcharhinus sp. (Carcharhinidae).

    Science.gov (United States)

    Soda, K J; Slice, D E; Naylor, G J P

    2017-01-01

    Over the past few decades, geometric morphometric methods have become increasingly popular and powerful tools to describe morphological data while over the same period artificial neural networks have had a similar rise in the classification of specimens to preconceived groups. However, there has been little research into how well these two systems operate together, particularly in comparison to preexisting techniques. In this study, geometric morphometric data and multilayer perceptrons, a style of artificial neural network, were used to classify shark teeth from the genus Carcharhinus to species. Three datasets of varying size and species differences were used. We compared the performance of this combination with geometric morphometric data in a linear discriminate function analysis, linear measurements in a linear discriminate function analysis, and a preexisting methodology from the literature that incorporates linear measurements and a two-layered discriminate function analysis. Across datasets, geometric morphometric data in a multilayer perceptron tended to yield modest accuracies but accuracies that varied less across species whereas other methods were able to achieve higher accuracies in some species at the expense of lower accuracies in others. Further, the performance of the two-layered discriminate function analysis illustrates that constraining what material is classified can increase the accuracy of a method. Based on this tradeoff, the best methodology will then depend on the scope of the study and the amount of material available. J. Morphol. 278:131-141, 2017. ©© 2016 Wiley Periodicals,Inc.

  9. A new geometric approach to Sturmian words

    CERN Document Server

    Matomäki, Kaisa

    2012-01-01

    We introduce a new geometric approach to Sturmian words by means of a mapping that associates certain lines in the n x n -grid and sets of finite Sturmian words of length n. Using this mapping, we give new proofs of the formulas enumerating the finite Sturmian words and the palindromic finite Sturmian words of a given length. We also give a new proof for the well-known result that a factor of a Sturmian word has precisely two return words.

  10. The minimal geometric deformation approach extended

    Science.gov (United States)

    Casadio, R.; Ovalle, J.; da Rocha, Roldão

    2015-11-01

    The minimal geometric deformation approach was introduced in order to study the exterior spacetime around spherically symmetric self-gravitating systems, such as stars or similar astrophysical objects, in the Randall-Sundrum brane-world framework. A consistent extension of this approach is developed here, which contains modifications of both the time component and the radial component of a spherically symmetric metric. A modified Schwarzschild geometry is obtained as an example of its simplest application, and a new solution that is potentially useful to describe stars in the brane-world is also presented.

  11. The Mousterian child from Teshik-Tash is a Neanderthal: a geometric morphometric study of the frontal bone.

    Science.gov (United States)

    Gunz, Philipp; Bulygina, Ekaterina

    2012-11-01

    In the 1930s subadult hominin remains and Mousterian artifacts were discovered in the Teshik-Tash cave in South Uzbekistan. Since then, the majority of the scientific community has interpreted Teshik-Tash as a Neanderthal. However, some have considered aspects of the morphology of the Teshik-Tash skull to be more similar to fossil modern humans such as those represented at Skhūl and Qafzeh, or to subadult Upper Paleolithic modern humans. Here we present a 3D geometric morphometric analysis of the Teshik-Tash frontal bone in the context of developmental shape changes in recent modern humans, Neanderthals, and early modern humans. We assess the phenetic affinities of Teshik-Tash to other subadult fossils, and use developmental simulations to predict possible adult shapes. We find that the morphology of the frontal bone places the Teshik-Tash child close to other Neanderthal children and that the simulated adult shapes are closest to Neanderthal adults. Taken together with genetic data showing that Teshik-Tash carried mtDNA of the Neanderthal type, as well as its occipital bun, and its shovel-shaped upper incisors, these independent lines of evidence firmly place Teshik-Tash among Neanderthals.

  12. Pig domestication and human-mediated dispersal in western Eurasia revealed through ancient DNA and geometric morphometrics.

    Science.gov (United States)

    Ottoni, Claudio; Flink, Linus Girdland; Evin, Allowen; Geörg, Christina; De Cupere, Bea; Van Neer, Wim; Bartosiewicz, László; Linderholm, Anna; Barnett, Ross; Peters, Joris; Decorte, Ronny; Waelkens, Marc; Vanderheyden, Nancy; Ricaut, François-Xavier; Cakirlar, Canan; Cevik, Ozlem; Hoelzel, A Rus; Mashkour, Marjan; Karimlu, Azadeh Fatemeh Mohaseb; Seno, Shiva Sheikhi; Daujat, Julie; Brock, Fiona; Pinhasi, Ron; Hongo, Hitomi; Perez-Enciso, Miguel; Rasmussen, Morten; Frantz, Laurent; Megens, Hendrik-Jan; Crooijmans, Richard; Groenen, Martien; Arbuckle, Benjamin; Benecke, Nobert; Vidarsdottir, Una Strand; Burger, Joachim; Cucchi, Thomas; Dobney, Keith; Larson, Greger

    2013-04-01

    Zooarcheological evidence suggests that pigs were domesticated in Southwest Asia ~8,500 BC. They then spread across the Middle and Near East and westward into Europe alongside early agriculturalists. European pigs were either domesticated independently or more likely appeared so as a result of admixture between introduced pigs and European wild boar. As a result, European wild boar mtDNA lineages replaced Near Eastern/Anatolian mtDNA signatures in Europe and subsequently replaced indigenous domestic pig lineages in Anatolia. The specific details of these processes, however, remain unknown. To address questions related to early pig domestication, dispersal, and turnover in the Near East, we analyzed ancient mitochondrial DNA and dental geometric morphometric variation in 393 ancient pig specimens representing 48 archeological sites (from the Pre-Pottery Neolithic to the Medieval period) from Armenia, Cyprus, Georgia, Iran, Syria, and Turkey. Our results reveal the first genetic signatures of early domestic pigs in the Near Eastern Neolithic core zone. We also demonstrate that these early pigs differed genetically from those in western Anatolia that were introduced to Europe during the Neolithic expansion. In addition, we present a significantly more refined chronology for the introduction of European domestic pigs into Asia Minor that took place during the Bronze Age, at least 900 years earlier than previously detected. By the 5th century AD, European signatures completely replaced the endemic lineages possibly coinciding with the widespread demographic and societal changes that occurred during the Anatolian Bronze and Iron Ages.

  13. Biomechanical implications of intraspecific shape variation in chimpanzee crania: moving toward an integration of geometric morphometrics and finite element analysis.

    Science.gov (United States)

    Smith, Amanda L; Benazzi, Stefano; Ledogar, Justin A; Tamvada, Kelli; Pryor Smith, Leslie C; Weber, Gerhard W; Spencer, Mark A; Dechow, Paul C; Grosse, Ian R; Ross, Callum F; Richmond, Brian G; Wright, Barth W; Wang, Qian; Byron, Craig; Slice, Dennis E; Strait, David S

    2015-01-01

    In a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. This results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that limits our ability to infer the significance of interspecific differences. This study uses geometric morphometric methods (GM) and finite element analysis (FEA) to examine the biomechanical implications of shape variation in chimpanzee crania, thereby providing a comparative context in which to interpret shape-related mechanical variation between hominin species. Six finite element models (FEMs) of chimpanzee crania were constructed from CT scans following shape-space Principal Component Analysis (PCA) of a matrix of 709 Procrustes coordinates (digitized onto 21 specimens) to identify the individuals at the extremes of the first three principal components. The FEMs were assigned the material properties of bone and were loaded and constrained to simulate maximal bites on the P(3) and M(2) . Resulting strains indicate that intraspecific cranial variation in morphology is associated with quantitatively high levels of variation in strain magnitudes, but qualitatively little variation in the distribution of strain concentrations. Thus, interspecific comparisons should include considerations of the spatial patterning of strains rather than focus only on their magnitudes. © 2014 Wiley Periodicals, Inc.

  14. Frontonasal dysmorphology in bipolar disorder by 3D laser surface imaging and geometric morphometrics: comparisons with schizophrenia.

    LENUS (Irish Health Repository)

    Hennessy, Robin J

    2010-09-01

    Any developmental relationship between bipolar disorder and schizophrenia engenders continuing debate. As the brain and face emerge in embryological intimacy, brain dysmorphogenesis is accompanied by facial dysmorphogenesis. 3D laser surface imaging was used to capture the facial surface of 13 male and 14 female patients with bipolar disorder in comparison with 61 male and 75 female control subjects and with 37 male and 32 female patients with schizophrenia. Surface images were analysed using geometric morphometrics and 3D visualisations to identify domains of facial shape that distinguish bipolar patients from controls and bipolar patients from those with schizophrenia. Both male and female bipolar patients evidenced significant facial dysmorphology: common to male and female patients was overall facial widening, increased width of nose, narrowing of mouth and upward displacement of the chin; dysmorphology differed between male and female patients for nose length, lip thickness and tragion height. There were few morphological differences in comparison with schizophrenia patients. That dysmorphology of the frontonasal prominences and related facial regions in bipolar disorder is more similar to than different from that found in schizophrenia indicates some common dysmorphogenesis. Bipolar disorder and schizophrenia might reflect similar insult(s) acting over slightly differing time-frames or slightly differing insult(s) acting over a similar time-frame.

  15. Dispelling dog dogma: an investigation of heterochrony in dogs using 3D geometric morphometric analysis of skull shape.

    Science.gov (United States)

    Drake, Abby Grace

    2011-01-01

    Heterochrony is an evolutionary mechanism that generates diversity via perturbations of the rate or timing of development that requires very little genetic innovation. As such, heterochrony is thought to be a common evolutionary mechanism in the generation of diversity. Previous research has suggested that dogs evolved via heterochrony and are paedomorphic wolves. This study uses three-dimensional landmark-based coordinate data to investigate heterochronic patterns within the skull morphology of the domestic dog. A total of 677 adult dogs representing 106 different breeds were measured and compared with an ontogenetic series of 401 wolves. Geometric morphometric analysis reveals that the cranial shape of none of the modern breeds of dogs resembles the cranial shapes of adult or juvenile wolves. In addition, investigations of regional heterochrony in the face and neurocranium also reject the hypothesis of heterochrony. Throughout wolf cranial development the position of the face and the neurocranium remain in the same plane. Dogs, however, have a de novo cranial flexion in which the palate is tilted dorsally in brachycephalic and mesaticephalic breeds or tilted ventrally in dolichocephalic and down-face breeds. Dogs have evolved very rapidly into an incredibly morphologically diverse species with very little genetic variation. However, the genetic alterations to dog cranial development that have produced this vast range of phylogenetically novel skull shapes do not coincide with the expectations of the heterochronic model. Dogs are not paedomorphic wolves.

  16. Geometric morphometrics of male facial shape in relation to physical strength and perceived attractiveness, dominance, and masculinity.

    Science.gov (United States)

    Windhager, Sonja; Schaefer, Katrin; Fink, Bernhard

    2011-01-01

    Evolutionary psychologists claim that women have adaptive preferences for specific male physical traits. Physical strength may be one of those traits, because recent research suggests that women rate faces of physically strong men as more masculine, dominant, and attractive. Yet, previous research has been limited in its ability to statistically map specific male facial shapes and features to corresponding physical measures (e.g., strength) and ratings (e.g., attractiveness). The association of handgrip strength (together with measures of shoulder width, body height, and body fat) and women's ratings of male faces (concerning dominance, masculinity, and attractiveness) were studied in a sample of 26 Caucasian men (aged 18-32 years). Geometric morphometrics was used to statistically assess the covariation of male facial shape with these measures. Statistical results were visualized with thin-plate spline deformation grids along with image unwarping and image averaging. Handgrip strength together with shoulder width, body fat, dominance, and masculinity loaded positively on the first dimension of covariation with facial shape (explaining 72.6%, P attractive and taller men had longer, narrower jaws and wider/fuller lips. Male physical strength was more strongly associated with changes in face shape that relate to perceived masculinity and dominance than to attractiveness. Our study adds to the growing evidence that attractiveness and dominance/masculinity may reflect different aspects of male mate quality. Copyright © 2011 Wiley-Liss, Inc.

  17. Pig Domestication and Human-Mediated Dispersal in Western Eurasia Revealed through Ancient DNA and Geometric Morphometrics

    Science.gov (United States)

    Ottoni, Claudio; Girdland Flink, Linus; Evin, Allowen; Geörg, Christina; De Cupere, Bea; Van Neer, Wim; Bartosiewicz, László; Linderholm, Anna; Barnett, Ross; Peters, Joris; Decorte, Ronny; Waelkens, Marc; Vanderheyden, Nancy; Ricaut, François-Xavier; Çakırlar, Canan; Çevik, Özlem; Hoelzel, A. Rus; Mashkour, Marjan; Mohaseb Karimlu, Azadeh Fatemeh; Sheikhi Seno, Shiva; Daujat, Julie; Brock, Fiona; Pinhasi, Ron; Hongo, Hitomi; Perez-Enciso, Miguel; Rasmussen, Morten; Frantz, Laurent; Megens, Hendrik-Jan; Crooijmans, Richard; Groenen, Martien; Arbuckle, Benjamin; Benecke, Nobert; Strand Vidarsdottir, Una; Burger, Joachim; Cucchi, Thomas; Dobney, Keith; Larson, Greger

    2013-01-01

    Zooarcheological evidence suggests that pigs were domesticated in Southwest Asia ∼8,500 BC. They then spread across the Middle and Near East and westward into Europe alongside early agriculturalists. European pigs were either domesticated independently or more likely appeared so as a result of admixture between introduced pigs and European wild boar. As a result, European wild boar mtDNA lineages replaced Near Eastern/Anatolian mtDNA signatures in Europe and subsequently replaced indigenous domestic pig lineages in Anatolia. The specific details of these processes, however, remain unknown. To address questions related to early pig domestication, dispersal, and turnover in the Near East, we analyzed ancient mitochondrial DNA and dental geometric morphometric variation in 393 ancient pig specimens representing 48 archeological sites (from the Pre-Pottery Neolithic to the Medieval period) from Armenia, Cyprus, Georgia, Iran, Syria, and Turkey. Our results reveal the first genetic signatures of early domestic pigs in the Near Eastern Neolithic core zone. We also demonstrate that these early pigs differed genetically from those in western Anatolia that were introduced to Europe during the Neolithic expansion. In addition, we present a significantly more refined chronology for the introduction of European domestic pigs into Asia Minor that took place during the Bronze Age, at least 900 years earlier than previously detected. By the 5th century AD, European signatures completely replaced the endemic lineages possibly coinciding with the widespread demographic and societal changes that occurred during the Anatolian Bronze and Iron Ages. PMID:23180578

  18. Describing shell shape variations and sexual dimorphism of Golden Apple Snail, Pomacea caniculata (Lamarck, 1822 using geometric morphometric analysis

    Directory of Open Access Journals (Sweden)

    C.C. Cabuga

    2017-09-01

    Full Text Available Pomacea caniculata or Golden Apple Snail (GAS existed to be a rice pest in the Philippines and in Asia. Likewise, geographic location also contributes its increasing populations thus making it invasive among freshwater habitats and rice field areas. This study was conducted in order to describe shell shape variations and sexual dimorphism among the populations of P. caniculata. A total of 180 were randomly collected in the three lakes of Esperanza, Agusan del Sur (Lake Dakong Napo, Lake Oro, and Lake Cebulan, of which each lake comprised of 60 samples (30 males and 30 females. To determine the variations and sexual dimorphism in the shell shape of golden apple snail, coordinates was administered to relative warp analysis and the resulting data were subjected to Multivariate Analysis of Variance (MANOVA, Principal Component Analysis (PCA and Canonical Variate Analysis (CVA. The results show statistically significant (P<0.05 from the appended male and female dorsal and ventral/apertural portion. While male and female spire height, body size, and shell shape opening also shows significant variations. These phenotypic distinctions could be associated with geographic isolation, predation and nutrient component of the gastropods. Thus, the importance of using geometric morphometric advances in describing sexual dimorphism in the shell shape of P. caniculata.

  19. Geometric and morphometric analysis of fish scales to identity genera, species and populations case study: the Cyprinid family

    Directory of Open Access Journals (Sweden)

    Seyedeh Narjes Tabatabei

    2014-01-01

    Full Text Available Using fish scale to identity species and population is a rapid, safe and low cost method. Hence, this study was carried out to investigate the possibility of using geometric and morphometric methods in fish scales for rapid identification of species and populations and compare the efficiency of applying few and/or high number of landmark points. For this purpose, scales of one population of Luciobarbus capito, four populations of Alburnoides eichwaldii and two populations of Rutilus frisii kutum, all belonging to cyprinid family, were examined. On two-dimensional images of the scales 7 and 23 landmark points were digitized in two separate times using TpsDig2, respectively. Landmark data after generalized procrustes analysis were analyzed using Principal Component Analysis (PCA, Canonical Variate Analysis (CVA and Cluster Analysis. The results of both methods (using 7 and 23 landmark points showed significant differences of the shape of scales among the three species studied (P0.05. The results also showed that few number of landmarks could display the differences between scale shapes. According to the results of this study, it could be stated that the scale of each species had unique shape patterns which could be utilized as a species identification key.

  20. A geometric morphometric analysis of hominin upper second and third molars, with particular emphasis on European Pleistocene populations.

    Science.gov (United States)

    Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

    2012-09-01

    The study of dental morphology by means of geometric morphometric methods allows for a detailed and quantitative comparison of hominin species that is useful for taxonomic assignment and phylogenetic reconstruction. Upper second and third molars have been studied in a comprehensive sample of Plio- and Pleistocene hominins from African, Asian and European sites in order to complete our analysis of the upper postcanine dentition. Intraspecific variation in these two molars is high, but some interspecific trends can be identified. Both molars exhibit a strong reduction of the distal cusps in recent hominin species, namely European Homo heidelbergensis, Homo neanderthalensis and Homo sapiens, but this reduction shows specific patterns and proportions in the three groups. Second molars tend to show four well developed cusps in earlier hominin species and their morphology is only marginally affected by allometric effects. Third molars can be incipiently reduced in earlier species and they evince a significant allometric component, identified both inter- and intraspecifically. European Middle Pleistocene fossils from Sima de los Huesos (SH) show a very strong reduction of these two molars, even more marked than the reduction observed in Neanderthals and in modern human populations. The highly derived shape of SH molars points to an early acquisition of typical Neanderthal dental traits by pre-Neanderthal populations and to a deviation of this population from mean morphologies of other European Middle Pleistocene groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Morphometric Evaluation of Korean Femurs by Geometric Computation: Comparisons of the Sex and the Population

    Directory of Open Access Journals (Sweden)

    Ho-Jung Cho

    2015-01-01

    Full Text Available We measured 28 parameters of 202 femurs from Koreans by an automated geometric computation program using 3D models generated from computed tomography images. The measurement parameters were selected with reference to physical and forensic anthropology studies as well as orthopedic implant design studies. All measurements were calculated using 3D reconstructions on a computer using scientific computation language. We also analyzed sex and population differences by comparison with data from previous studies. Most parameters were larger in males than in females. The height, head diameter, head center offset, and chord length of the diaphysis, most parameters in the distal femur, and the isthmic width of the medullary canal were smaller in Koreans than in other populations. However, the neck-shaft angle, subtense, and width of the intercondylar notch in the distal femur were larger than those in other populations. The results of this study will be useful as a reference for physical and forensic anthropology as well as the design of medical devices suitable for Koreans.

  2. Geometric Approach to Lie Symmetry of Discrete Time Toda Equation

    Institute of Scientific and Technical Information of China (English)

    JIA Xiao-Yu; WANG Na

    2009-01-01

    By using the extended Harrison and Estabrook geometric approach,we investigate the Lie symmetry of discrete time Toda equation from the geometric point of view.Its one-dimensional continuous symmetry group is presented.

  3. Geometric morphometrics and molecular systematics of Xanthocnemis sobrina (McLachlan, 1873) (Odonata: Coenagrionidae) and comparison to its congeners.

    Science.gov (United States)

    Marinov, Milen; Amaya-Perilla, Catalina; Holwell, Gregory I; Varsani, Arvind; Bysterveldt, Katherine Van; Kraberger, Simona; Stainton, Daisy; Dayaram, Anisha; Curtis, Nathan; Cruickshank, Robert H; Paterson, Adrian

    2016-02-09

    The taxonomy of the damselfly genus Xanthocnemis is revised, with particular focus on populations inhabiting the North Island of New Zealand. Earlier studies revealed two species: X. sobrina, restricted to cool, shaded streams in kauri forests and other forested areas, and X. zealandica, a common species throughout New Zealand except the Chatham and subantarctic islands. A field study encompassing aquatic habitats throughout the whole North Island was carried out to establish the relationship between morphological variation (body size and various morphological traits over the entire body) observed by previous researchers with ecological conditions and/or geographical location. The main aim was to propose reliable diagnostic features that could be used in future studies. Morphological and molecular variation was assessed. Morphological examination included assigning landmarks for all body parts corresponding to the external morphological features that are usually used in Odonata taxonomy. Molecular analysis targeted fragments of the 28S and 16S rRNA genes. Congruence was sought between both types of data, statistical support for two morphological types previously described as different species and a maximum likelihood phylogenetic tree in conjunction with a pairwise genetic distance matrix constructed from the DNA sequences obtained from the sampled specimens. Geometric morphometrics revealed statistically significant differentiation between specimens identified as X. zealandica and X. sobrina for four traits: (1) dorsal view of the head for both sexes as well as male appendages from (2) dorsal, (3) ventral and (4) lateral views. Wings appeared different when analysed for males only. Molecular analysis, however, grouped all specimens into a single undifferentiated cluster with very low mean pairwise distance (96% and ~93% pairwise identity with X. tuanuii sequences obtained from the Chatham Island specimens. A careful investigation of the thin plate spline

  4. Estimating the magnitude of morphoscapes: how to measure the morphological component of biodiversity in relation to habitats using geometric morphometrics

    Science.gov (United States)

    Fontaneto, Diego; Panisi, Martina; Mandrioli, Mauro; Montardi, Dario; Pavesi, Maurizio; Cardini, Andrea

    2017-08-01

    Ecological indicators are currently developed to account for the different facets of loss of biological diversity due to direct or indirect effects of human activities. Most ecological indicators include species richness as a metric. Others, such as functional traits and phylogenetic diversity, account for differences in species, even when species richness is the same. Here, we describe and apply a different indicator, called morphoscape dimension, accounting for morphological variability across habitats in a geographical region. We use the case of ground beetles (Coleoptera: Carabidae) in four different habitats in the Po Plain in Northern Italy to exemplify how to quantify the magnitude of the morphological space (i.e. the dimension of the morphoscape) occupied by the species in each habitat using geometric morphometrics. To this aim, we employed a variety of metrics of morphological disparity related to univariate size, and more complex multivariate shape and form. Our `proof of concept' suggests that metrics assessing size and form might largely tend to simply mirror the information provided by species richness, whereas shape morphoscape disparity may be able to account for non-trivial differences in species traits amongst habitats. This is indicated by the woodland morphoscape being on average bigger than that of crops, the most species-rich habitat, despite having almost 20% less species. We conclude suggesting that the analysis of morphoscape dimension has the potential to become a new additional and complimentary tool in the hands of conservation biologists and ecologists to explore and quantify habitat complexity and inform decisions on management and conservation based on a wide set of ecological indicators.

  5. Three-dimensional geometric morphometric analysis of talar morphology in extant gorilla taxa from highland and lowland habitats.

    Science.gov (United States)

    Knigge, Ryan P; Tocheri, Matthew W; Orr, Caley M; Mcnulty, Kieran P

    2015-01-01

    Western gorillas (Gorilla gorilla) are known to climb significantly more often than eastern gorillas (Gorilla beringei), a behavioral distinction attributable to major differences in their respective habitats (i.e., highland vs. lowland). Genetic evidence suggests that the lineages leading to these taxa began diverging from one another between approximately 1 and 3 million years ago. Thus, gorillas offer a special opportunity to examine the degree to which morphology of recently diverged taxa may be "fine-tuned" to differing ecological requirements. Using three-dimensional (3D) geometric morphometrics, we compared talar morphology in a sample of 87 specimens including western (lowland), mountain (highland), and grauer gorillas (lowland and highland populations). Talar shape was captured with a series of landmarks and semilandmarks superimposed by generalized Procrustes analysis. A between-group principal components analysis of overall talar shape separates gorillas by ecological habitat and by taxon. An analysis of only the trochlea and lateral malleolar facet identifies subtle variations in trochlear shape between western lowland and lowland grauer gorillas, potentially indicative of convergent evolution of arboreal adaptations in the talus. Lastly, talar shape scales differently with centroid size for highland and lowland gorillas, suggesting that ankle morphology may track body-size mediated variation in arboreal behaviors differently depending on ecological setting. Several of the observed shape differences are linked biomechanically to the facilitation of climbing in lowland gorillas and to stability and load-bearing on terrestrial substrates in the highland taxa, providing an important comparative model for studying morphological variation in groups known only from fossils (e.g., early hominins).

  6. Geometric morphometric analysis of allometric variation in the mandibular morphology of the hominids of Atapuerca, Sima de los Huesos site.

    Science.gov (United States)

    Rosas, Antonio; Bastir, Markus

    2004-06-01

    Allometry is an important factor of morphological integration that contributes to the organization of the phenotype and its variation. Variation in the allometric shape of the mandible is particularly important in hominid evolution because the mandible carries important taxonomic traits. Some of these traits are known to covary with size, particularly the retromolar space, symphyseal curvature, and position of the mental foramen. The mandible is a well studied system in the context of the evolutionary development of complex morphological structures because it is composed of different developmental units that are integrated within a single bone. In the present study, we investigated the allometric variation of two important developmental units that are separated by the inferior nerve (a branch of CN V3). We tested the null hypothesis that there would be no difference in allometric variation between the two components. Procrustes-based geometric morphometrics of 20 two-dimensional (2D) landmarks were analyzed by multivariate regressions of shape on size in samples from 121 humans, 48 chimpanzees, and 50 gorillas (all recent specimens), eight fossil hominids from Atapuerca, Sima de los Huesos (AT-SH), and 17 Neandertals. The findings show that in all of the examined species, there was significantly greater allometric variation in the supra-nerve unit than in the infra-nerve unit. The formation of the retromolar space exhibited an allometric relationship with the supra-nerve unit in all of the species studied. The formation of the chin-like morphology is an "apodynamic" feature of the infra-nerve unit in the AT-SH hominids. The results of this study support the hypothesis that allometry contributes to the organization of variation in complex morphological structures. Copyright 2004 Wiley-Liss, Inc.

  7. Detecting taxonomic signal in an under-utilised character system: geometric morphometrics of the forcipular coxae of Scutigeromorpha (Chilopoda

    Directory of Open Access Journals (Sweden)

    Beatriz Lopez Gutierrez

    2011-12-01

    Full Text Available To date, the forcipules have played almost no role in determining the systematics of scutigeromorph centipedes though in his 1974 review of taxonomic characters Markus Würmli suggested some potentially informative variation might be found in these structures. Geometric morphometric analyses were used to evaluate Würmli’s suggestion, specifically to determine whether the shape of the forcipular coxa contains information useful for diagnosing species. The geometry of the coxae of eight species from the genera Sphendononema, Scutigera, Dendrothereua, Thereuonema, Thereuopoda, Thereuopodina, Allothereua and Parascutigera was characterised using a combination of landmark- and semi-landmark-based sampling methods to summarize group-specific morphological variation. Canonical variates analysis of shape data characterizing the forcipular coxae indicates that these structures differ significantly between taxa at various systematic levels. Models calculated for the canonical variates space facilitate identification of the main shape differences between genera, including overall length/width, curvature of the external coxal margin, and the extent to which the coxofemoral condyle projects laterally. Jackknifed discriminant function analysis demonstrates that forcipular coxal training-set specimens were assigned to correct species in 61% of cases on average, the most accurate assignments being those of Parascutigera (P. guttata and Thereuonema (T. microstoma. The geographically widespread species Thereuopoda longicornis, Sphendononema guildingii, Scutigera coleoptrata, and Dendrothereua linceci exhibit the least diagnostic coxae in our dataset. Thereuopoda longicornis populations sampled from different parts of East and Southeast Asia were significantly discriminated from each other, suggesting that, in this case, extensive synonymy may be obscuring diagnosable inter-species coxal shape differences.

  8. Morphometric Approach to Pulp Fibroblast Development in Tooth Germ

    Directory of Open Access Journals (Sweden)

    Irina-Draga Căruntu

    2014-01-01

    Full Text Available This paper builds a morphometric framework for the analysis of dental pulp fibroblast evolution during tooth development. We investigated 15 tooth germs (cases organized, by histological criteria, in three groups corresponding to cap, early bell, and late bell stages, respectively. Each group comprised five cases. The morphometric description used the following parameters: area A, perimeter P—automatically extracted by a color segmentation technique, and form factor (FF—calculated as 4πA/P2. The designed framework operated at inter- and intragroup levels. The intergroup analysis quantified the differences between groups, in the sense of a relative distance (RD adequately defined by mean-value scaling. We showed that the stage of early bell is approximately 5 times closer to late bell than to cap. The quantification procedure required concomitant information about A, P parameters (as P versus A dependences, or FF values, whereas the procedure failed for A or P separately used. The intragroup analysis quantified the similarity of the cases belonging to the same stage. We proved that, unlike the intergroup tests, the individual exploitation of all three descriptors A, P, and FF is effective, yielding highly compatible results. Within any group, most cases presented RDs less than 10% from the group mean value, regardless of the descriptor type.

  9. A geometric approach to acyclic orientations

    CERN Document Server

    Ehrenborg, Richard

    2009-01-01

    The set of acyclic orientations of a connected graph with a given sink has a natural poset structure. We give a geometric proof of a result of Jim Propp: this poset is the disjoint union of distributive lattices.

  10. Anisotropy without tensors: a novel approach using geometric algebra.

    Science.gov (United States)

    Matos, Sérgio A; Ribeiro, Marco A; Paiva, Carlos R

    2007-11-12

    The most widespread approach to anisotropic media is dyadic analysis. However, to get a geometrical picture of a dielectric tensor, one has to resort to a coordinate system for a matrix form in order to obtain, for example, the index-ellipsoid, thereby obnubilating the deeper coordinate-free meaning of anisotropy itself. To overcome these shortcomings we present a novel approach to anisotropy: using geometric algebra we introduce a direct geometrical interpretation without the intervention of any coordinate system. By applying this new approach to biaxial crystals we show the effectiveness and insight that geometric algebra can bring to the optics of anisotropic media.

  11. A Geometric Approach to Fair Division

    Science.gov (United States)

    Barbanel, Julius

    2010-01-01

    We wish to divide a cake among some collection of people (who may have very different notions of the comparative value of pieces of cake) in a way that is both "fair" and "efficient." We explore the meaning of these terms, introduce two geometric tools to aid our analysis, and present a proof (due to Dietrich Weller) that establishes the existence…

  12. Geometric Reductivity--A Quotient Space Approach

    CERN Document Server

    Sastry, Pramathanath

    2010-01-01

    We give another proof that a reductive algebraic group is geometrically reductive. We show that a quotient of the semi-stable locus (by a linear action of a reductive algebraic group on a projective scheme) exists, and from this Haboush's Theorem (Mumford's Conjecture) follows.

  13. A Geometric Approach to Fair Division

    Science.gov (United States)

    Barbanel, Julius

    2010-01-01

    We wish to divide a cake among some collection of people (who may have very different notions of the comparative value of pieces of cake) in a way that is both "fair" and "efficient." We explore the meaning of these terms, introduce two geometric tools to aid our analysis, and present a proof (due to Dietrich Weller) that establishes the existence…

  14. Cryptic Species or Inadequate Taxonomy? Implementation of 2D Geometric Morphometrics Based on Integumental Organs as Landmarks for Delimitation and Description of Copepod Taxa.

    Science.gov (United States)

    Karanovic, Tomislav; Djurakic, Marko; Eberhard, Stefan M

    2016-03-01

    Discovery of cryptic species using molecular tools has become common in many animal groups but it is rarely accompanied by morphological revision, creating ongoing problems in taxonomy and conservation. In copepods, cryptic species have been discovered in most groups where fast-evolving molecular markers were employed. In this study at Yeelirrie in Western Australia we investigate a subterranean species complex belonging to the harpacticoid genus Schizopera Sars, 1905, using both the barcoding mitochondrial COI gene and landmark-based two-dimensional geometric morphometrics. Integumental organs (sensilla and pores) are used as landmarks for the first time in any crustacean group. Complete congruence between DNA-based species delimitation and relative position of integumental organs in two independent morphological structures suggests the existence of three distinct evolutionary units. We describe two of them as new species, employing a condensed taxonomic format appropriate for cryptic species. We argue that many supposedly cryptic species might not be cryptic if researchers focus on analyzing morphological structures with multivariate tools that explicitly take into account geometry of the phenotype. A perceived supremacy of molecular methods in detecting cryptic species is in our view a consequence of disparity of investment and unexploited recent advancements in morphometrics among taxonomists. Our study shows that morphometric data alone could be used to find diagnostic morphological traits and gives hope to anyone studying small animals with a hard integument or shell, especially opening the door to assessing fossil diversity and rich museum collections. We expect that simultaneous use of molecular tools with geometry-oriented morphometrics may yield faster formal description of species. Decrypted species in this study are a good example for urgency of formal descriptions, as they display short-range endemism in small groundwater calcrete aquifers in a

  15. A geometrical approach to structural change modeling

    OpenAIRE

    Stijepic, Denis

    2013-01-01

    We propose a model for studying the dynamics of economic structures. The model is based on qualitative information regarding structural dynamics, in particular, (a) the information on the geometrical properties of trajectories (and their domains) which are studied in structural change theory and (b) the empirical information from stylized facts of structural change. We show that structural change is path-dependent in this model and use this fact to restrict the number of future structural cha...

  16. A Geometrical Approach to the Boundary Element Method

    CERN Document Server

    Auchmann, B; Rjasanow, S

    2008-01-01

    We introduce a geometric formulation of the boundary element method (BEM), using concepts of the discrete electromagnetic theory. Geometric BEM is closely related to Galerkin-BEM and to the generalized collocation scheme. It is easy to implement, accurate, and computationally efficient. We validate our approach with 2-D examples and give an outlook to 3-D results.

  17. Parabolic non-diffracting beams: geometrical approach

    Science.gov (United States)

    Sosa-Sánchez, Citlalli Teresa; Silva-Ortigoza, Gilberto; Alejandro Juárez-Reyes, Salvador; de Jesús Cabrera-Rosas, Omar; Espíndola-Ramos, Ernesto; Julián-Macías, Israel; Ortega-Vidals, Paula

    2017-08-01

    The aim of this work is to present a geometrical characterization of parabolic non-diffracting beams. To this end, we compute the corresponding angular spectrum of the separable non-diffracting parabolic beams in order to determine the one-parameter family of solutions of the eikonal equation associated with this type of beam. Using this information, we compute the corresponding wavefronts and caustic, and find that qualitatively the caustic corresponds to the maximum of the intensity pattern and the wavefronts are deformations of conical surfaces.

  18. A geometric approach to integrability conditions for Riccati equations

    Directory of Open Access Journals (Sweden)

    Arturo Ramos

    2007-09-01

    Full Text Available Several instances of integrable Riccati equations are analyzed from the geometric perspective of the theory of Lie systems. This provides us a unifying viewpoint for previous approaches.

  19. Implicit quasilinear differential systems: a geometrical approach

    Directory of Open Access Journals (Sweden)

    Miguel C. Munoz-Lecanda

    1999-04-01

    Full Text Available This work is devoted to the study of systems of implicit quasilinear differential equations. In general, no set of initial conditions is admissible for the system. It is shown how to obtain a vector field whose integral curves are the solution of the system, thus reducing the system to one that is ordinary. Using geometrical techniques, we give an algorithmic procedure in order to solve these problems for systems of the form $A(xdot x =alpha (x$ with $A(x$ being a singular matrix. As particular cases, we recover some results of Hamiltonian and Lagrangian Mechanics. In addition, a detailed study of the symmetries of these systems is carried out. This algorithm is applied to several examples arising from technical applications related to control theory.

  20. Describing head shapes of white stem borers (Schirpophaga innotata Walker that are able to survive on different rice types using Landmark based geometric morphometrics

    Directory of Open Access Journals (Sweden)

    Queenilyn B. Albutra

    2012-06-01

    Full Text Available Rice stem borers are considered as the most serious insect pest of rice in Asia. It infects itsplant host by burrowing into the stem using its mandible. However, apart from the mandible, the head ofrice stem borers is also associated in the incursion process since it facilitates the entry of larvae to the riceplant. Differences in the head capsules have a direct effect on the ability of the insects to ingest hardfoods rapidly. Different rice varieties in the Philippines serve as plant host for this pest and infestationoccurred in different geographical location. Variations in habitat and plant host were thought to generateenvironmental variation in morphometric traits and host adapted herbivore phenotype respectively.Landmark based geometric morphometric analysis was used to assess the hypothesis that the head shapeof white stem borer differ between populations with respect to different rice varieties and geographicallocation where it was obtained. Relative warp analysis showed variation in the head shape betweendifferent white stem borer (Schirpophaga innotata Walker populations infesting different varieties of rice.Non-significant head shape variations were obtained between geographically separated populations. Theseresults indicate that the rice host varieties play an important role in the selection of individuals that areable to counteract the resistance factors in plants.

  1. Geometrical approach to light in inhomogeneous media

    CERN Document Server

    Piwnicki, P

    2002-01-01

    Electromagnetism in an inhomogeneous dielectric medium at rest is described using the methods of differential geometry. In contrast to a general relativistic approach the electromagnetic fields are discussed in three-dimensional space only. The introduction of an appropriately chosen three-dimensional metric leads to a significant simplification of the description of light propagation in an inhomogeneous medium: light rays become geodesics of the metric and the field vectors are parallel transported along the rays. The new metric is connected to the usual flat space metric diag[1,1,1] via a conformal transformation leading to new, effective values of the medium parameters leading to an effective constant value of the index of refraction n=1. The corresponding index of refraction is thus constant and so is the effective velocity of light. Space becomes effectively empty but curved. All deviations from straight line propagation are now due to curvature. The approach is finally used for a discussion of the Riema...

  2. Morphometrics, 3D Imaging, and Craniofacial Development

    Science.gov (United States)

    Hallgrimsson, Benedikt; Percival, Christopher J.; Green, Rebecca; Young, Nathan M.; Mio, Washington; Marcucio, Ralph

    2017-01-01

    Recent studies have shown how volumetric imaging and morphometrics can add significantly to our understanding of morphogenesis, the developmental basis for variation and the etiology of structural birth defects. On the other hand, the complex questions and diverse imaging data in developmental biology present morphometrics with more complex challenges than applications in virtually any other field. Meeting these challenges is necessary in order to understand the mechanistic basis for variation in complex morphologies. This chapter reviews the methods and theory that enable the application of modern landmark-based morphometrics to developmental biology and craniofacial development, in particular. We discuss the theoretical foundations of morphometrics as applied to development and review the basic approaches to the quantification of morphology. Focusing on geometric morphometrics, we discuss the principal statistical methods for quantifying and comparing morphological variation and covariation structure within and among groups. Finally, we discuss the future directions for morphometrics in developmental biology that will be required for approaches that enable quantitative integration across the genotype-phenotype map. PMID:26589938

  3. A geometric approach to the Makeenko-Migdal equations

    Energy Technology Data Exchange (ETDEWEB)

    Gambini, R.; Griego, J. (Universidad de la Republica, Montevideo (Uruguay). Facultad de Humanidades y Ciencias Universidad de la Republica, Montevideo (Uruguay). Facultad de Ingenieria)

    1991-03-14

    A rigorous geometric approach of the Yang-Mills dynamics in loop space is developed using the algebraic structure of the group of loops. For the SU(N) gauge theory all the relevant constraints are explicitly introduced, obtaining a closed Makeenko-Migdal type equation when N=2. (orig.).

  4. First comparative phenetic studies of Argentinean species of Acacia (Fabaceae), using morphometric, isozymal, and RAPD approaches.

    Science.gov (United States)

    Casiva, Paola V; Saidman, Beatriz O; Vilardi, Juan C; Cialdella, Ana M

    2002-05-01

    Morphological and genetic diversity among Acacia aroma, A. macracantha, A. caven, and A. furcatispina were studied with morphometric, isozymal, and RAPD approaches. The analysis of seven isozyme systems revealed 21 loci, and RAPD analysis showed 34 loci. Most of these loci allowed us to differentiate the species, with the exception of A. aroma and A. macracantha, the two most similar species. The levels of genetic variability estimated by isozymes were higher than those obtained from RAPD analyses. Morphometric characters showed highly significant differences among the species, although A. aroma and A. macracantha are differentiated only by thorn length. The phenogram obtained from isozyme data is consistent with morphological data. The RAPD phenogram based on allelic frequencies showed agreement with morphological and isozymal approaches only at the intraspecific levels, while the RAPD phenogram based on Nei and Li's similarity measures agreed with the phenograms constructed from isozyme and morphological data. High similarities and high indirect gene flow were found between A. aroma and A. macracantha, results that call the relationship between them into question.

  5. Hadronic and elementary multiplicity distributions in a geometrical approach

    CERN Document Server

    Valin, P; Menon, M J

    2000-01-01

    We construct the hadronic multiplicity distribution in terms of an elementary distribution (at given impact parameter) and the inelastic overlap function characterized by the observed BEL (Blacker-Edgier-Larger) behaviour. With suitable parametrizations for the elementary quantities, based on some geometrical arguments and the most recent data on e+e- annihilation, an excellent description of pp and p(bar)p inelastic multiplicity distributions at the highest energies is obtained. With this approach, we quantitatively correlate the violations of scalings in multiplicity distributions (Koba-Nielsen-Olesen) and elastic scattering (Geometrical) at high energies.

  6. Optimal control of underactuated mechanical systems: A geometric approach

    Science.gov (United States)

    Colombo, Leonardo; Martín De Diego, David; Zuccalli, Marcela

    2010-08-01

    In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

  7. Optimal Control of Underactuated Mechanical Systems: A Geometric Approach

    CERN Document Server

    Colombo, L; Zuccalli, M

    2009-01-01

    In this paper, we consider a geometric formalism for optimal control of underactuated mechanical systems. Our techniques are an adaptation of the classical Skinner and Rusk approach for the case of Lagrangian dynamics with higher-order constraints. We study a regular case where it is possible to establish a symplectic framework and, as a consequence, to obtain a unique vector field determining the dynamics of the optimal control problem. These developments will allow us to develop a new class of geometric integrators based on discrete variational calculus.

  8. Superlogic manifolds and geometric approach to quantum logic

    Science.gov (United States)

    da Costa, Newton; Kouneiher, Joseph

    2016-10-01

    The main purpose of this paper is to present a new approach to logic or what we will call superlogic. This approach constitutes a new way of looking at the connection between quantum mechanics and logic. It is a geometrization of the quantum logic. Note that this superlogic is not distributive reflecting a good propriety to describe quantum mechanics, non-commutative spaces and contains a nilpotent element.

  9. Outline and landmark based geometric morphometric analysis in describing sexual dimorphism in wings of the white stem borer (Schirpophaga innotata Walker

    Directory of Open Access Journals (Sweden)

    Queenilyn B. Albutra

    2012-06-01

    Full Text Available Many studies about wing morphology have been conducted in the field of entomology that aims to clarify the relationship in closelyrelated taxa and to identify different population within and between species. However, less has been reported that exploit wing shape morphologyto discriminate female and male population within species. Differences in wing morphology between sexes of the same species of insectsoften reflect disparity in flight performance and flight range which might be of considerable significance in the monitoring and control of pestspecies. This study was conducted to determine differences in flight morphology between sexes of the white stem borer (Schirpophaga innotaWalker by looking at variation in the shapes of the entire wing and its compartments using the method of geometric morphometrics. The resultsshowed considerable variation in the forewings and hindwings between female and male specimen as shown in relative warp analysis.Discriminant function analysis and MANOVA also showed statistically significant wing shape variation between sexes demonstrating the presenceof sexual dimorphism within the species of white stem borers.

  10. Application of geometric morphometrics to the study of postnatal size and shape changes in the skull of Calomys expulsus

    Directory of Open Access Journals (Sweden)

    Erika Hingst-Zaher

    2000-06-01

    Full Text Available Abstract We analyzed ontogenetic patterns of landmarks for 169 laboratory-raised specimens of Calomys expulsus, at 0, 5, 10, 20, 30, 50, 100, 200, and 300 days of age, using two-dimensional geometric morphometrics. There is sexual dimorphism in size, with males smaller than females at earlier ages, but larger after 50 days. Differences in shape between sexes are strong only until 10 days of age, suggesting that shape is more constrained than size. Combining sexes, there is strong variation in size with age, reduced after 200 days, while most of the variation in shape occurs before 20 days. This dissociation is common for sigmodontine rodents, and might be the basis of heterochronic processes responsible for the morphological variation of this South American group. Centroid size does not show any reduction in the coefficient of variation over ages, while Procrustes distances within sucessive ages are reduced after 20 days. Uniform component and the more global partial warps explain most of the shape changes with age. Cranial and Facial parts of the skull increase in size at different rates with a relative lengthening of the snout and decrease in height of the braincase. We were unable to detect a clear pattern of integration for the rostrum and braincase, besides that shown by landmark displacements.

  11. Quantitation of nasal development in the early prenatal period using geometric morphometrics and MRI: a new insight into the critical period of Binder phenotype.

    Science.gov (United States)

    Katsube, Motoki; Yamada, Shigehito; Miyazaki, Reina; Yamaguchi, Yutaka; Makishima, Haruyuki; Takakuwa, Tetsuya; Yamamoto, Akira; Fujii, Yosuke; Morimoto, Naoki; Ito, Tsuyoshi; Imai, Hirohiko; Suzuki, Shigehiko

    2017-09-01

    Disturbance of the development of the nasal septum in the early prenatal period causes congenital facial anomalies characterized by a flat nose and defects of the anterior nasal spine (ANS), such as Binder phenotype. The present research aimed to assess the development of the nasal septum and the ANS with growth in the early prenatal period. Magnetic resonance images were obtained from 56 specimens. Mid-sagittal images were analyzed by using geometric morphometrics for the development of the nasal septum, and angle analysis was performed for the development of the ANS. Additionally, we calculated and visualized the ontogenetic allometry of the nasal septum. Our results showed that the nasal septum changed shape in the anteroposterior direction in smaller specimens, while it maintained an almost isometric shape in larger specimens. Furthermore, mathematical evidence revealed that the maturation periods of the shapes of the ANS and the nasal septum were around 12 and 14 weeks of gestation, respectively. The anteroposterior development of the nasal septum is specific until 14 weeks of gestation, and it is important for nasal protrusion and the development of the ANS. Therefore, the disturbance of such development could induce low nasal deformity, including Binder phenotype. © 2017 John Wiley & Sons, Ltd. © 2017 John Wiley & Sons, Ltd.

  12. Ontogenetic scaling of caudal fin shape in Squalus acanthias (Chondrichthyes, Elasmobranchii): a geometric morphometric analysis with implications for caudal fin functional morphology.

    Science.gov (United States)

    Reiss, Katie L; Bonnan, Matthew F

    2010-07-01

    The shark heterocercal caudal fin and its contribution to locomotion are of interest to biologists and paleontologists. Current hydrodynamic data show that the stiff dorsal lobe leads the ventral lobe, both lobes of the tail are synchronized during propulsion, and tail shape reflects its overall locomotor function. Given the difficulties surrounding the analysis of shark caudal fins in vivo, little is known about changes in tail shape related to ontogeny and sex in sharks. A quantifiable analysis of caudal fin shape may provide an acceptable proxy for inferring gross functional morphology where direct testing is difficult or impossible. We examined ontogenetic and sex-related shape changes in the caudal fins of 115 Squalus acanthias museum specimens, to test the hypothesis that significant shape changes in the caudal fin shape occur with increasing size and between the sexes. Using linear and geometric morphometrics, we examined caudal shape changes within the context of current hydrodynamic models. We found no statistically significant linear or shape difference between sexes, and near-isometric scaling trends for caudal dimensions. These results suggest that lift and thrust increase linearly with size and caudal span. Thin-plate splines results showed a significant allometric shape change associated with size and caudal span: the dorsal lobe elongates and narrows, whereas the ventral lobe broadens and expands ventrally. Our data suggest a combination of caudal fin morphology with other body morphology aspects, would refine, and better elucidate the hydrodynamic factors (if any) that underlie the significant shape changes we report here for S. acanthias.

  13. Evidence of at least two evolutionary lineages in Melipona subnitida (Apidae, Meliponini) suggested by mtDNA variability and geometric morphometrics of forewings

    Science.gov (United States)

    Bonatti, Vanessa; Simões, Zilá Luz Paulino; Franco, Fernando Faria; Francoy, Tiago Mauricio

    2014-01-01

    Melipona subnitida, a tropical stingless bee, is an endemic species of the Brazilian northeast and exhibits great potential for honey and pollen production in addition to its role as one of the main pollinators of the Caatinga biome. To understand the genetic structure and better assist in the conservation of this species, we characterized the population variability of M. subnitida using geometric morphometrics of the forewing and cytochrome c oxidase I gene fragment sequencing. We collected workers from six localities in the northernmost distribution. Both methodologies indicated that the variability among the sampled populations is related both to the environment in which samples were collected and the geographical distance between the sampling sites, indicating that differentiation among the populations is due to the existence of at least evolutionary lineages. Molecular clock data suggest that this differentiation may have begun in the middle Pleistocene, approximately 396 kya. The conservation of all evolutionary lineages is important since they can present differential resistance to environmental changes, as resistance to drought and diseases.

  14. Locomotion in some small to medium-sized mammals: a geometric morphometric analysis of the penultimate lumbar vertebra, pelvis and hindlimbs.

    Science.gov (United States)

    Álvarez, Alicia; Ercoli, Marcos D; Prevosti, Francisco J

    2013-12-01

    We assessed the influence of a variety of aspects of locomotion and ecology including gait and locomotor types, maximal running speed, home range, and body size on postcranial shape variation in small to medium-sized mammals, employing geometric morphometric analysis and phylogenetic comparative methods. The four views analyzed, i.e., dorsal view of the penultimate lumbar vertebra, lateral view of the pelvis, posterior view of the proximal femur and proximal view of the tibia, showed clear phylogenetic signal and interesting patterns of association with movement. Variation in home range size was related to some tibia shape changes, while speed was associated with lumbar vertebra, pelvis and tibia shape changes. Femur shape was not related to any locomotor variables. In both locomotor type and high-speed gait analyses, locomotor groups were distinguished in both pelvis and tibia shape analyses. These results suggest that adaptations to both typical and high-speed gaits could explain a considerable portion of the shape of those elements. In addition, lumbar vertebra and tibia showed non-significant relationships with body mass, which suggests that they might be used in morpho-functional analyses and locomotor inferences on fossil taxa, with little or no bias for body size. Lastly, we observed morpho-functional convergences among several mammalian taxa and detected some taxa that achieve similar locomotor features following different morphological paths.

  15. Dominance of quantum over classical correlations: entropic and geometric approach

    OpenAIRE

    Walczak, Zbigniew; Wintrowicz, Iwona; Zakrzewska, Katarzyna

    2013-01-01

    Recently, it has been shown that there exist quantum states for which quantum correlations dominate over classical correlations. Inspired by this observation, we investigate the problem of quantum correlations dominance for two-qubit Bell diagonal states in the Ollivier--Zurek paradigm, using both entropic and geometric approach to quantification of classical and quantum correlations. In particular, we estimate numerically the amount of two-qubit Bell diagonal states for which quantum correla...

  16. Geometrical approach to central molecular chirality: a chirality selection rule

    OpenAIRE

    Capozziello, S.; Lattanzi, A

    2004-01-01

    Chirality is of primary importance in many areas of chemistry and has been extensively investigated since its discovery. We introduce here the description of central chirality for tetrahedral molecules using a geometrical approach based on complex numbers. According to this representation, for a molecule having n chiral centres, it is possible to define an index of chirality. Consequently a chirality selection rule has been derived which allows the characterization of a molecule as achiral, e...

  17. Super-resolved imaging geometrical and diffraction approaches

    CERN Document Server

    2011-01-01

    In this brief we review several approaches that provide super resolved imaging, overcoming the geometrical limitation of the detector as well as the diffraction effects set by the F number of the imaging lens. In order to obtain the super resolved enhancement, we use spatially non-uniform and/or random transmission structures to encode the image or the aperture planes. The desired resolution enhanced images are obtained by post-processing decoding of the captured data.

  18. Is the morphology of Culicoides intersexes parasitized by mermithid nematodes a parasite adaptation? A morphometric approach to Culicoides circumscriptus (Diptera: Ceratopogonidae).

    Science.gov (United States)

    Muñoz-Muñoz, Francesc; Ramoneda, Josep; Pagès, Nonito; Pujol, Nuria; Talavera, Sandra

    2016-03-01

    Mermithidae is a family of endoparasitic nematodes known to cause intersexuality in arthropods. Intersexes of the genus Culicoides parasitized by mermithids have been the object of several studies aiming to describe their particular morphology. Culicoides intersexes are specimens with male genitalia and feminized sexually dimorphic structures, i.e. antennae, mouthparts and wings. To date, these specimens have only been described qualitatively and a quantitative approach supported by statistical analysis is lacking. Here we conduct morphometric analyses of sexually dimorphic structures in a sample of Culicoides circumscriptus that includes 34 intersexes with the aim of describing precisely the intersexual morphology. The morphology of antennae and the mouthparts was studied by multivariate statistical analysis of linear measures, and wing form by implementing geometric morphometrics techniques. While intersex wings proved to have a similar size to male wings, their shape was intermediate between males and females. However, when allometric shape variation was removed, the wing shape of intersexes was almost identical to that of females. The intersex antennae were morphometrically of the female type, especially when size variation was considered. In contrast, the measured mouthparts (the labrum and the third palpal segment) were halfway between males and females, even when body size was considered. Overall, the antennae and the wings showed a higher degree of feminization than the mouthparts. These findings indicate that the degree of feminization depends both on the morphological structure and on body size. Moreover, we propose that the feminization of the wings and antennae has an adaptive meaning for the parasite, which would favor female-like traits in order to access more easily its breeding sites, where the parasite has plenty of new hosts to infect. Female-like antennae would be beneficial to detect these sites, while having female-like wings would favor the

  19. Shape variability of the adult human acetabulum and acetabular fossa related to sex and age by geometric morphometrics. Implications for adult age estimation.

    Science.gov (United States)

    San-Millán, Marta; Rissech, Carme; Turbón, Daniel

    2017-03-01

    This study aims to explore shape variability of the acetabulum during the human adult life span, in relation to sex and age. The human acetabular shape was analysed in 682 os coxae from three different documented skeletal collections from the Iberian Peninsula. Two landmarks and thirty-two sliding semi-landmarks were used for the geometric morphometric procedures and a clock-wise standard was used for orientation. The 180° meridian (6:00) line was positioned over the midpoint of the acetabular notch and 36 reference points in 10° increments along the rim were marked. Data showed that size, sex and age significantly influence acetabular shape variation. Sex differences were significant in individuals younger than 65 years old and were characterised by males exhibiting relatively extended acetabular rim profiles from 10:00 to 1:00, narrower acetabular notches, and reduced acetabular fossae. In addition, three main age-related changes occurred to the acetabular shape in both sexes: outer acetabular profile modification, with extension from 10:00 to 1:00 and reduction from 7:00 to 9:00, acetabular notch narrowing, and acetabular fossa reduction. The age-related changes that were observed are shared by both sexes and seem to be related to bone production associated with age. Specifically, age appears to affect the entire border of the lunate surface: the acetabular rim, both acetabular horns, and the outer edge of the acetabular fossa. Furthermore, shape data confirmed the clover-leaf shape of the acetabular fossa in both males and females. These results improve our understanding of acetabular shape, and assist in refining age-estimation methods and enhancing hip surgery and rehabilitation.

  20. Geometric morphometric analysis of intratrackway variability: a case study on theropod and ornithopod dinosaur trackways from Münchehagen (Lower Cretaceous, Germany)

    Science.gov (United States)

    van Heteren, Anneke H.; Wings, Oliver

    2016-01-01

    trackways. Geometric morphometric analysis reveals potential for improvement of existing discriminant methods. PMID:27330855

  1. Patterns of postnatal ontogeny of the skull and lower jaw of snakes as revealed by micro-CT scan data and three-dimensional geometric morphometrics.

    Science.gov (United States)

    Palci, Alessandro; Lee, Michael S Y; Hutchinson, Mark N

    2016-12-01

    We compared the head skeleton (skull and lower jaw) of juvenile and adult specimens of five snake species [Anilios (=Ramphotyphlops) bicolor, Cylindrophis ruffus, Aspidites melanocephalus, Acrochordus arafurae, and Notechis scutatus] and two lizard outgroups (Ctenophorus decresii, Varanus gilleni). All major ontogenetic changes observed were documented both qualitatively and quantitatively. Qualitative comparisons were based on high-resolution micro-CT scanning of the specimens, and detailed quantitative analyses were performed using three-dimensional geometric morphometrics. Two sets of landmarks were used, one for accurate representation of the intraspecific transformations of each skull and jaw configuration, and the other for comparison between taxa. Our results document the ontogenetic elaboration of crests and processes for muscle attachment (especially for cervical and adductor muscles); negative allometry in the braincase of all taxa; approximately isometric growth of the snout of all taxa except Varanus and Anilios (positively allometric); and positive allometry in the quadrates of the macrostomatan snakes Aspidites, Acrochordus and Notechis, but also, surprisingly, in the iguanian lizard Ctenophorus. Ontogenetic trajectories from principal component analysis provide evidence for paedomorphosis in Anilios and peramorphosis in Acrochordus. Some primitive (lizard-like) features are described for the first time in the juvenile Cylindrophis. Two distinct developmental trajectories for the achievement of the macrostomatan (large-gaped) condition in adult snakes are documented, driven either by positive allometry of supratemporal and quadrate (in pythons), or of quadrate alone (in sampled caenophidians); this is consistent with hypothesised homoplasy in this adaptive complex. Certain traits (e.g. shape of coronoid process, marginal tooth counts) are more stable throughout postnatal ontogeny than others (e.g. basisphenoid keel), with implications for their

  2. Evolution of opercle bone shape along a macrohabitat gradient: species identification using mtDNA and geometric morphometric analyses in neotropical sea catfishes (Ariidae).

    Science.gov (United States)

    Stange, Madlen; Aguirre-Fernández, Gabriel; Cooke, Richard G; Barros, Tito; Salzburger, Walter; Sánchez-Villagra, Marcelo R

    2016-08-01

    Transitions between the marine and freshwater macrohabitat have occurred repeatedly in the evolution of teleost fishes. For example, ariid catfishes have moved from freshwater to marine environments, and vice versa. Opercles, a skeletal feature that has been shown to change during such transitions, were subjected to 2D geometric morphometric analyses in order to investigate evolutionary shape changes during habitat transition in ariid catfishes and to test the influence of habitat on shape changes. A mtDNA marker, which proved useful in previous studies, was used to verify species identities. It greatly improved the assignment of specimens to a species, which are difficult to assign by morphology alone. The application of a mtDNA marker confirmed the occurrence of Notarius biffi in Central America, South of El Salvador. Molecular identification together with principal component analysis (PCA) and further morphological inspection of neurocrania indicated the existence of a cryptic species within Bagre pinnimaculatus. Principal component (PC) scores of individual specimens clustered in morphospace by genus rather than by habitat. Strong phylogenetic structure was detected using a permutation test of PC scores of species means on a phylogenetic tree. Calculation of Pagel's λ suggested that opercle shape evolved according to a Brownian model of evolution. Yet canonical variate analysis (CVA) conducted on the habitat groups showed significant differences in opercle shapes among freshwater and marine species. Overall, opercle shape in tropical American Ariidae appears to be phylogenetically constrained. This verifies the application of opercle shape as a taxonomic tool for species identification in fossil ariid catfishes. At the same time, adaptation to freshwater habitats shows characteristic opercle shape trajectories in ariid catfishes, which might be used to detect habitat preferences in fossils.

  3. A geometric morphometrics comparative analysis of Neandertal humeri (epiphyses-fused) from the El Sidrón cave site (Asturias, Spain).

    Science.gov (United States)

    Rosas, Antonio; Pérez-Criado, Laura; Bastir, Markus; Estalrrich, Almudena; Huguet, Rosa; García-Tabernero, Antonio; Pastor, Juan Francisco; de la Rasilla, Marco

    2015-05-01

    A new collection of 49,000 year old Neandertal fossil humeri from the El Sidrón cave site (Asturias, Spain) is presented. A total of 49 humeral remains were recovered, representing 10 left and 8 right humeri from adults, adolescents, and a juvenile (not included in the analyses). 3D geometric morphometric (GM) methods as well as classic anthropological variables were employed to conduct a broad comparative analysis by means of mean centroid size and shape comparisons, principal components analysis, and cluster studies. Due to the fragmentary nature of the fossils, comparisons were organized in independent analyses according to different humeral portions: distal epiphysis, diaphysis, proximal epiphysis, and the complete humerus. From a multivariate viewpoint, 3D-GM analyses revealed major differences among taxonomic groups, supporting the value of the humerus in systematic classification. Notably, the Australopithecus anamensis (KP-271) and Homo ergaster Nariokotome (KNM-WT 15000) distal humerus consistently clusters close to those of modern humans, which may imply a primitive condition for Homo sapiens morphology. Australopithecus specimens show a high degree of dispersion in the morphospace. The El Sidrón sample perfectly fits into the classic Neandertal pattern, previously described as having a relatively wide olecranon fossa, as well as thin lateral and medial distodorsal pillars. These characteristics were also typical of the Sima de los Huesos (Atapuerca) sample, African mid-Pleistocene Bodo specimen, and Lower Pleistocene TD6-Atapuerca remains and may be considered as a derived state. Finally, we hypothesize that most of the features thought to be different between Neandertals and modern humans might be associated with structural differences in the pectoral girdle and shoulder joint. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Phenotypic differentiation of the Red Sea gastropods in response to the environmental deterioration: Geometric morphometric approach

    Science.gov (United States)

    Abdelhady, Ahmed Awad

    2016-03-01

    The negative impacts of degradation in the coastal zone of the Red Sea are becoming well known in upper portions of the trophic web (e.g., humans and fish), but are less well known among the benthic primary consumers. In addition, the degree to which heavy metals are entering the trophic web can be better-quantified using macrobenthos. Two-gastropod genera encompassing Echinolittorina subnodosa and Planaxis sulcatus from three different localities on the Egyptian coast of the Red Sea were examined in order to deduce the impact of environmental deterioration on the morphology of shells. The examined sites include clean pristine, slightly polluted, and markedly polluted rocky shores. Phosphate/lead industry is the main source of pollution in this zone. Because landmarks on the rugose Echinolittorina are difficult to define and to ensure finer resolution of the analyses, a newly 'grid-based' landmarks was implemented. Both Canonical Variate Analysis (CVA) and Thin Plate Spline (TPS) were particularly capable to capture and terrace the minor morphological variations accurately. Two phenotypes portioned among the environmentally different populations were recognized and interpreted as ecotypes with many intermediate forms. The first ecotype has a higher spire and smaller aperture and dominating the pristine site North of Marsa Alam, whereas the second ecotype has a globular shell shape with big aperture and dominating the markedly polluted site. The intermediate forms dominating the slightly polluted site. The shape differences are interpreted as an adaptive differentiation to different metal concentrations. As the morphological variation between the two-ecotypes of both taxa is still minors, and both ecotypes occur together with many intermediate forms, the phenotypic divergence stage has not yet accomplished. The gradational shape change among the investigated populations was positively correlated with index of Pollution (IP). As the human activities were the main driver of the phenotypic changes, hence anthropogenic impact may shift the evolution and/or the extinction rates.

  5. A geometric approach for radiation transport inside complex systems

    Energy Technology Data Exchange (ETDEWEB)

    Fumeron, S. [Groupe de Recherche en Ingenierie des Procedes et Systemes, Departement des Sciences Appliquees, Universite du Quebec a Chicoutimi, 555 Boulevard de l' Universite, Chicoutimi, PQ (Canada)]. E-mail: sebastien_fumeron@uqac.ca

    2006-09-04

    The aim of this Letter is to extend the phenomenological theory of radiation transfer to complex systems. For elastic or electromagnetic waves, one presents a geometrization of matter based on relativistic gravitation models. In this approach, particles experience material media as curved spacetimes, which locally affect the energetic processes. The general form of Clausius invariant is calculated and the curved radiative transfer equation is derived. An application to phonon transport in solids shows that the presence of a defect can amplify the elastic energy carried in particular directions of propagation.

  6. Palatal growth in complete unilateral cleft lip and palate patients following neonatal cheiloplasty: Classic and geometric morphometric assessment.

    Science.gov (United States)

    Hoffmannova, Eva; Bejdová, Šárka; Borský, Jiri; Dupej, Ján; Cagáňová, Veronika; Velemínská, Jana

    2016-11-01

    A new method of early neonatal cheiloplasty has recently been employed on patients having complete unilateral cleft lip and palate (cUCLP). We aimed to investigate (1) their detailed palatal morphology before surgery and growth during the 10 months after neonatal cheiloplasty, (2) the growth of eight dimensions of the maxilla in these patients, (3) the development of these dimensions compared with published data on noncleft controls and on cUCLP patients operated using later operation protocol (LOP; 6 months of age). Sixty-six virtual dental models of 33 longitudinally evaluated cUCLP patients were analysed using metric analysis, a dense correspondence model, and multivariate statistics. We compared the palatal surfaces before neonatal cheiloplasty (mean age, 4 days) and before palatoplasty (mean age, 10 months). The palatal form variability of 10-month-old children was considerably reduced during the observed period thanks to their undisturbed growth, that is, the palate underwent the same growth changes following neonatal cheiloplasty. A detailed colour-coded map identified the most marked growth at the anterior and posterior ends of both segments. The maxilla of cUCLP patients after neonatal cheiloplasty had a growth tendency similar to noncleft controls (unlike LOP). Both methodological approaches showed that early neonatal cheiloplasty in cUCLP patients did not prevent forward growth of the upper jaw segments and did not reduce either the length or width of the maxilla during the first 10 months of life. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. A geometric approach to noncommutative principal torus bundles

    DEFF Research Database (Denmark)

    Wagner, Stefan

    2013-01-01

    for noncommutative algebras and say that a dynamical system (A, 핋n,α) is called a noncommutative principal 핋n-bundle, if localization leads to a trivial noncommutative principal 핋n-bundle. We prove that this approach extends the classical theory of principal torus bundles and present a bunch of (nontrivial......A (smooth) dynamical system with transformation group 핋n is a triple (A, 핋n,α), consisting of a unital locally convex algebra A, the n-torus 핋n and a group homomorphism α:핋n→Aut(A), which induces a (smooth) continuous action of 핋n on A. In this paper, we present a new, geometrically oriented...... approach to the noncommutative geometry of principal torus bundles based on such dynamical systems. Our approach is inspired by the classical setting: In fact, after recalling the definition of a trivial noncommutative principal torus bundle, we introduce a convenient (smooth) localization method...

  8. Morphometrics applied to medical entomology.

    Science.gov (United States)

    Dujardin, Jean-Pierre

    2008-12-01

    Morphometrics underwent a revolution more than one decade ago. In the modern morphometrics, the estimate of size is now contained in a single variable reflecting variation in many directions, as many as there are landmarks under study, and shape is defined as their relative positions after correcting for size, position and orientation. With these informative data, and the corresponding software freely available to conduct complex analyses, significant biological and epidemiological features can be quantified more accurately. We discuss the evolutionary significance of the environmental impact on metric variability, mentioning the importance of concepts like genetic assimilation, genetic accommodation, and epigenetics. We provide examples of measuring the effect of selection on metric variation by comparing (unpublished) Qst values with corresponding (published) Fst. The primary needs of medical entomologists are to distinguish species, especially cryptic species, and to detect them where they are not expected. We explain how geometric morphometrics could apply to these questions, and where there are deficiencies preventing the approach from being utilized at its maximum potential. Medical entomologists in connection with control programs aim to identify isolated populations where the risk of reinfestation after treatment would be low ("biogeographical islands"). Identifying them can be obtained from estimating the number of migrants per generation. Direct assessment of movement remains the most valid approach, but it scores active movement only. Genetic methods estimating gene flow levels among interbreeding populations are commonly used, but gene flow does not necessarily mean the current flow of migrants. Methods using the morphometric variation are neither suited to evaluate gene flow, nor are they adapted to estimate the flow of migrants. They may provide, however, the information needed to create a preliminary map pointing to relevant areas where one could

  9. D-brane superpotentials: Geometric and worldsheet approaches

    Energy Technology Data Exchange (ETDEWEB)

    Baumgartl, Marco, E-mail: m.baumgartl@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany); Brunner, Ilka, E-mail: ilka.brunner@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany); Soroush, Masoud, E-mail: masoud.soroush@physik.uni-muenchen.d [Arnold Sommerfeld Center, Ludwig-Maximilians-Universitaet, Theresienstr. 37, Muenchen 80333 (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, Garching 85748 (Germany)

    2011-02-21

    From the worldsheet perspective, the superpotential on a D-brane wrapping internal cycles of a Calabi-Yau manifold is given as a generating functional for disk correlation functions. On the other hand, from the geometric point of view, D-brane superpotentials are captured by certain chain integrals. In this work, we explicitly show for branes wrapping internal two-cycles how these two different approaches are related. More specifically, from the worldsheet point of view, D-branes at the Landau-Ginzburg point have a convenient description in terms of matrix factorizations. We use a formula derived by Kapustin and Li to explicitly evaluate disk correlators for families of D2-branes. On the geometry side, we then construct a three-chain whose period gives rise to the effective superpotential and show that the two expressions coincide. Finally, as an explicit example, we choose a particular compact Calabi-Yau hypersurface and compute the effective D2-brane superpotential in different branches of the open moduli space, in both geometric and worldsheet approaches.

  10. NEW APPROACH FOR IMAGE REPRESENTATION BASED ON GEOMETRIC STRUCTURAL CONTENTS

    Institute of Scientific and Technical Information of China (English)

    Jia Xiaomeng; Wang Guoyu

    2003-01-01

    This paper presents a novel approach for representation of image contents based on edge structural features. Edge detection is carried out for an image in the pre-processing stage.For feature representation, edge pixels are grouped into a set of segments through geometrical partitioning of the whole edge image. Then the invariant feature vector is computed for each edge-pixel segment. Thereby the image is represented with a set of spatially distributed feature vectors, each of which describes the local pattern of edge structures. Matching of two images can be achieved by the correspondence of two sets of feature vectors. Without the difficulty of image segmentation and object extraction due to the complexity of the real world images, the proposed approach provides a simple and flexible description for the image with complex scene, in terms of structural features of the image content. Experiments with real images illustrate the effectiveness of this new method.

  11. Geometrical approach to the evaluation of multileg Feynman diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Davydychev, A.I. [Department of Physics, University of Mainz, Mainz (Germany); Delbourgo, R. [Physics Department, University of Tasmania, Hobart, Tasmania (Australia)

    1998-10-01

    A connection between one-loop N-point Feynman diagrams and certain geometrical quantities in non-Euclidean geometry is discussed. A geometrical way to calculate the corresponding Feynman integrals is considered. (author)

  12. Geometric Approaches to Quadratic Equations from Other Times and Places.

    Science.gov (United States)

    Allaire, Patricia R.; Bradley, Robert E.

    2001-01-01

    Focuses on geometric solutions of quadratic problems. Presents a collection of geometric techniques from ancient Babylonia, classical Greece, medieval Arabia, and early modern Europe to enhance the quadratic equation portion of an algebra course. (KHR)

  13. Approach to Weighted Geometric Evaluation Based on Projection Pursuit

    Institute of Scientific and Technical Information of China (English)

    Yang Shanlin; Wang Shuo; Gong Daning

    2006-01-01

    Weighted geometric evaluation approach based on Projection pursuit (PP) model is presented in this paper to optimize the choice of schemes. By using PP model, the multi-dimension evaluation index values of schemes can be synthesized into projection value with one dimension. The scheme with a bigger projection value is much better, so the schemes sample can be an optimized choice according to the projection value of each scheme. The modeling of PP based on accelerating genetic algorithm can predigest the realized process of projection pursuit technique, can overcome the shortcomings of large computation amount and the difficulty of computer programming in traditional projection pursuit methods, and can give a new method for application of projection pursuit technique to optimize choice of schemes by using weighted geometric evaluation. The analysis of an applied sample shows that applying PP model driven directly by samples data to optimize choice of schemes is both simple and feasible, that its projection values are relatively decentralized and profit decision-making, that its applicability and maneuverability are high. It can avoid the shortcoming of subjective weighing method, and its results are scientific and objective.

  14. A Geometric Approach to the Six Trigonometric Ratios.

    Science.gov (United States)

    Bonsangue, Martin V.

    1993-01-01

    Geometric interpretations and derivations of the six trigonometric relationships are demonstrated. Selected for discussion are limiting values, geometric verification of trigonometric identities, a one-dimensional illustration of the Pythagorean relationships, and the geometric derivation of infinite-series relationships. (DE)

  15. Some Asymptotic Inference in Multinomial Nonlinear Models (a Geometric Approach)

    Institute of Scientific and Technical Information of China (English)

    WEIBOCHENG

    1996-01-01

    A geometric framework is proposed for multinomlat nonlinear modelsbased on a modified vemlon of the geometric structure presented by Bates & Watts[4]. We use this geometric framework to study some asymptotic inference in terms ofcurvtures for multlnomial nonlinear models. Our previous results [15] for ordlnary nonlinear regression models are extended to multlnomlal nonlinear models.

  16. A geometrical approach to degenerate scalar-tensor theories

    CERN Document Server

    Chagoya, Javier

    2016-01-01

    Degenerate scalar-tensor theories are recently proposed covariant theories of gravity coupled with a scalar field. Despite being characterised by higher order equations of motion, they do not propagate more than three degrees of freedom, thanks to the existence of constraints. We discuss a geometrical approach to degenerate scalar-tensor systems, and analyse its consequences. We show that some of these theories emerge as a certain limit of DBI Galileons. In absence of dynamical gravity, these systems correspond to scalar theories enjoying a symmetry which is different from Galileon invariance. The scalar theories have however problems concerning the propagation of fluctuations around a time dependent background. These issues can be tamed by breaking the symmetry by hand, or by minimally coupling the scalar with dynamical gravity in a way that leads to degenerate scalar-tensor systems. We show that distinct theories can be connected by a relation which generalizes Galileon duality, in certain cases also when g...

  17. Geometric approach to viscous fingering on a cone

    CERN Document Server

    Miranda, J A

    2003-01-01

    We study fluid flow and the formation of viscous fingering patterns on a two-dimensional conical background space, defined as the conical Hele-Shaw cell. We approach the problem geometrically and study how the nontrivial topological structure of the conical cell affects the evolution of the interface separating two viscous fluids. We perform a perturbative weakly nonlinear analysis of the problem and derive a mode-coupling differential equation which describes fluid-fluid interface behaviour. Our nonlinear study predicts the formation of fingering structures in which fingers of different lengths compete and split at their tips. The shape of the emerging patterns show a significant sensitivity to variations in the cell's topological features, which can be monitored by changing the cone opening angle. We find that for increasingly larger values of the opening angle, finger competition is inhibited while finger tip-splitting is enhanced.

  18. A GIS-based approach in drainage morphometric analysis of Kanhar River Basin, India

    Science.gov (United States)

    Rai, Praveen Kumar; Mohan, Kshitij; Mishra, Sameer; Ahmad, Aariz; Mishra, Varun Narayan

    2017-03-01

    The study indicates that analysis of morphometric parameters with the help of geographic information system (GIS) would prove a viable method of characterizing the hydrological response behaviour of the watershed. It is also well observed that remote sensing satellite data is emerging as the most effective, time saving and accurate technique for morphometric analysis of a basin. This technique is found relevant for the extraction of river basin and its stream networks through ASTER (DEM) in conjunction with remote sensing satellite data (Landsat etm+, 2013 and georeferenced survey of Indian toposheet, 1972). In this study, Kanhar basin a tributaries of Son River has been selected for detailed morphometric analysis. Seven sub-watersheds are also delineated within this basin to calculate the selected morphometric parameters. Morphometric parameters viz; stream order, stream length, bifurcation ratio, drainage density, stream frequency, form factor, circulatory ratio, etc., are calculated. The drainage area of the basin is 5,654 km2 and shows sub-dendritic to dendritic drainage pattern. The stream order of the basin is mainly controlled by physiographic and lithological conditions of the area. The study area is designated as seventh-order basin with the drainage density value being as 1.72 km/km2. The increase in stream length ratio from lower to higher order shows that the study area has reached a mature geomorphic stage.

  19. A Protocol for the Creation of Useful Geometric Shape Metrics Illustrated with a Newly Derived Geometric Measure of Leaf Circularity

    Directory of Open Access Journals (Sweden)

    Jonathan D. Krieger

    2014-08-01

    Full Text Available Premise of the study: I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. Methods and Results: To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. Conclusions: The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors.

  20. A protocol for the creation of useful geometric shape metrics illustrated with a newly derived geometric measure of leaf circularity.

    Science.gov (United States)

    Krieger, Jonathan D

    2014-08-01

    I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. • To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. • The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors.

  1. Growth and Allometry in Modern Morphometrics: Review

    Directory of Open Access Journals (Sweden)

    Deniz SIĞIRLI

    2013-01-01

    Full Text Available In traditional shape analysis, linear distance, angles and ratios of measurements are used in multivariate statistical analyses. The challenge in any analysis of growth is to extend quantitative description and to explore aspects of the biology of a given organism, such as the genetic basis of morphogenesis, the phylogenetic underpinnings of developmental patterns, or the role of hormones, teratogens, dietary elements, and other environmental variables on the growth process. It is important to define the growth process with mathematical equations that include biologically meaningful parameters. Size has several different meanings such as length, area, volume, and even the linear combinations of different measured quantities. However, in statistical shape analysis, size is obtained by a specific approach, which provides the geometrical information of an object. Allometry theory was developed as a result of shape variations that occur with the growth of an organism’s different parts or organs at different rates. As the idea of size and shape has been one of the most controversial subjects in traditional morphometrics, allometry (relationship between size and shape plays an important role in the development of statistical shape analysis. The quantities used in traditional morphometrics for size are highly correlated with shape. Thus, many different methods have been proposed for size correction. However, because of disagreement regarding relevant methods of size correction, researchers have investigated different methods for the analysis of shape data. Today, new geometrical morphometric approaches are being used extensively to explore and model growth and allometry.

  2. A new approach toward geometrical concept of black hole thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Hendi, Seyed Hossein [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of); Panahiyan, Shahram; Panah, Behzad Eslam; Momennia, Mehrab [Shiraz University, Physics Department and Biruni Observatory, College of Sciences, Shiraz (Iran, Islamic Republic of)

    2015-10-15

    Motivated by the energy representation of Riemannian metric, in this paper we study different approaches toward the geometrical concept of black hole thermodynamics. We investigate thermodynamical Ricci scalar of Weinhold, Ruppeiner and Quevedo metrics and show that their number and location of divergences do not coincide with phase transition points arisen from heat capacity. Next, we introduce a new metric to solve these problems. We show that the denominator of the Ricci scalar of the new metric contains terms which coincide with different types of phase transitions. We elaborate the effectiveness of the new metric and shortcomings of the previous metrics with some examples. Furthermore, we find a characteristic behavior of the new thermodynamical Ricci scalar which enables one to distinguish two types of phase transitions. In addition, we generalize the new metric for the cases of more than two extensive parameters and show that in these cases the divergencies of thermodynamical Ricci scalar coincide with phase transition points of the heat capacity. (orig.)

  3. Traditional and Modern Morphometrics: Review

    Directory of Open Access Journals (Sweden)

    Gökhan OCAKOĞLU

    2013-01-01

    Full Text Available Morphometrics, a branch of morphology, is the study of the size and shape components of biological forms and their variation in the population. In biological and medical sciences, there is a long history of attempts to quantitatively express the diversity of the size and shape of biological forms. On the basis of historical developments in morphometry, we address several questions related to the shape of organs or organisms that are considered in biological and medical studies. In the field of morphometrics, multivariate statistical analysis is used to rigorously address such questions. Historically, these methods have involved the analysis of collections of distances or angles, but recent theoretical, computational, and other advances have shifted the focus of morphometric procedures to the Cartesian coordinates of anatomical points. In recent years, in biology and medicine, the traditional morphometric studies that aim to analyze shape variation have been replaced by modern morphometric studies. In the biological and medical sciences, morphometric methods are frequently preferred for examining the morphologic structures of organs or organisms with regard to diseases or environmental factors. These methods are also preferred for evaluating and classifying the variation of organs or organisms with respect to growth or allometry time dependently. Geometric morphometric methods are more valid than traditional morphometric methods in protecting more morphological information and in permitting analysis of this information.

  4. Morphometric evaluation of Swarnrekha watershed, Madhya Pradesh, India: an integrated GIS-based approach

    Science.gov (United States)

    Banerjee, Abhishek; Singh, Prafull; Pratap, Kamleshwar

    2017-07-01

    The quantitative analysis of the watershed is vital to understand the hydrological setup of any terrain. The present study deals with quantitative evaluation of Swarnrekha Watershed, Madhya Pradesh, India based on IRS satellite data and SRTM DEM. Morphometric parameters of the watershed were evaluated by computations of linear and areal aspect using standard methodology in GIS environment. ARC GIS software was utilized for morphometric component analysis and delineation of the watershed using SRTM digital elevation model (DEM). The watershed is drained by a fifth-order river and shown a dendritic drainage pattern, which is a sign of the homogeneity in texture and lack of structural control. The drainage density in the area has been found to be low which indicates that the area possesses highly permeable soils and low relief. The bifurcation ratio varies from 3.00 to 5.60 and elongation ratio is 0.518 which reveals that the basin belongs to the elongated shape basin and has the potential for water management. The main objective of the paper is to extract the morphometric parameters of the watershed and their relevance in water resource evaluation management. The results observed from this work would be useful in categorization of watershed for future water management and selection recharge structure in the area.

  5. Morphometric evaluation of Swarnrekha watershed, Madhya Pradesh, India: an integrated GIS-based approach

    Science.gov (United States)

    Banerjee, Abhishek; Singh, Prafull; Pratap, Kamleshwar

    2015-10-01

    The quantitative analysis of the watershed is vital to understand the hydrological setup of any terrain. The present study deals with quantitative evaluation of Swarnrekha Watershed, Madhya Pradesh, India based on IRS satellite data and SRTM DEM. Morphometric parameters of the watershed were evaluated by computations of linear and areal aspect using standard methodology in GIS environment. ARC GIS software was utilized for morphometric component analysis and delineation of the watershed using SRTM digital elevation model (DEM). The watershed is drained by a fifth-order river and shown a dendritic drainage pattern, which is a sign of the homogeneity in texture and lack of structural control. The drainage density in the area has been found to be low which indicates that the area possesses highly permeable soils and low relief. The bifurcation ratio varies from 3.00 to 5.60 and elongation ratio is 0.518 which reveals that the basin belongs to the elongated shape basin and has the potential for water management. The main objective of the paper is to extract the morphometric parameters of the watershed and their relevance in water resource evaluation management. The results observed from this work would be useful in categorization of watershed for future water management and selection recharge structure in the area.

  6. Geometric Programming Approach to an Interactive Fuzzy Inventory Problem

    Directory of Open Access Journals (Sweden)

    Nirmal Kumar Mandal

    2011-01-01

    Full Text Available An interactive multiobjective fuzzy inventory problem with two resource constraints is presented in this paper. The cost parameters and index parameters, the storage space, the budgetary cost, and the objective and constraint goals are imprecise in nature. These parameters and objective goals are quantified by linear/nonlinear membership functions. A compromise solution is obtained by geometric programming method. If the decision maker is not satisfied with this result, he/she may try to update the current solution to his/her satisfactory solution. In this way we implement man-machine interactive procedure to solve the problem through geometric programming method.

  7. A Geometric Approach to Massive p-form Duality

    CERN Document Server

    Arias, P J; Pérez-Mosquera, J C; Arias, Pio J.; Leal, Lorenzo; Perez-Mosquera, Jean Carlos

    2003-01-01

    Massive theories of abelian p-forms are quantized in a generalized path-representation that leads to a description of the phase space in terms of a pair of dual non-local operators analogous to the Wilson Loop and the 't Hooft disorder operators. Special atention is devoted to the study of the duality between the Topologically Massive and the Self-Dual models in 2+1 dimensions. It is shown that these models share a geometric representation in which just one non local operator suffices to describe the observables. For the Proca model its geometric representation is constructed from two Self-Dual representations by direct product.

  8. Combining geometric morphometrics with molecular genetics to investigate a putative hybrid complex: a case study with barbels Barbus spp. (Teleostei: Cyprinidae).

    Science.gov (United States)

    Geiger, M F; Schreiner, C; Delmastro, G B; Herder, F

    2016-03-01

    This integrative study examined the morphological and genetic affinities of three endemic barbel species from Italy (brook barbel Barbus caninus, Italian barbel Barbus plebejus and horse barbel Barbus tyberinus) and of putative hybrid specimens to their species of origin. Two of the species frequently occur together with the non-native barbel Barbus barbus. DNA barcoding indicates that mitochondrial (mt) haplotypes often do not match the species expected from morphology. Linear distance measurements and meristics are not informative for discrimination of the species and putative hybrids, but a discriminant analysis of principal components (DAPC) of geometric landmark data produces reassignments largely in congruence with mt and nuclear genetic data. Cyto-nuclear conflicts confirm the presence of hybridization in B. plebejus and B. tyberinus and identify additional introgressed specimens. A comparison between mixed genotypes and their morphology-based assignment reveals no predictable pattern. The finding that most individuals of the morphologically similar B. plebejus and B. tyberinus have very high assignment probabilities to their respective species suggests that the presented approach may serve as a valuable tool to distinguish morphologically very similar taxa.

  9. Geometric and Algebraic Approaches in the Concept of Complex Numbers

    Science.gov (United States)

    Panaoura, A.; Elia, I.; Gagatsis, A.; Giatilis, G.-P.

    2006-01-01

    This study explores pupils' performance and processes in tasks involving equations and inequalities of complex numbers requiring conversions from a geometric representation to an algebraic representation and conversions in the reverse direction, and also in complex numbers problem solving. Data were collected from 95 pupils of the final grade from…

  10. Material inhomogeneities and their evolution a geometric approach

    CERN Document Server

    Epstein, Marcelo

    2007-01-01

    Presents a unified treatment of the inhomogeneity theory using some of the tools of modern differential geometry. This book deals with the geometrical description of uniform bodies and their homogeneity conditions. It also develops a theory of material evolution and discusses its relevance in various applied contexts.

  11. Taxonomic revision of the Malagasy Nesomyrmex madecassus species-group using a quantitative morphometric approach.

    Science.gov (United States)

    Csősz, Sándor; Fisher, Brian L

    2016-01-01

    Here we reveal the diversity of the next fragment of the Malagasy elements of the ant genus Nesomyrmex using a combination of advanced exploratory analyses on quantitative morphological data. The diversity of the Nesomyrmex madecassus species-group was assessed via hypothesis-free nest centroid clustering combined with recursive partitioning to estimate the number of clusters and determine the most probable boundaries between them. This combination of methods provides a highly automated species delineation protocol based on continuous morphometric data, and thereby it obviates the need of subjective interpretation of morphological patterns. Delimitations of clusters recognized by these exploratory analyses were tested via confirmatory Linear Discriminant Analysis (LDA). Our results suggest the existence of four morphologically distinct species, Nesomyrmex flavus sp. n., Nesomyrmex gibber, Nesomyrmex madecassus and Nesomyrmex nitidus sp. n.; all are described here and an identification key for their worker castes using morphometric data is given. Two members of the newly outlined madecasus species-group, Nesomyrmex flavus sp. n. and Nesomyrmex nitidus sp. n., represent true cryptic species. Geographic maps depicting species distributions and elevational information for the sites where populations of particular species were collected are also provided.

  12. A Geometric Fuzzy-Based Approach for Airport Clustering

    Directory of Open Access Journals (Sweden)

    Maria Nadia Postorino

    2014-01-01

    Full Text Available Airport classification is a common need in the air transport field due to several purposes—such as resource allocation, identification of crucial nodes, and real-time identification of substitute nodes—which also depend on the involved actors’ expectations. In this paper a fuzzy-based procedure has been proposed to cluster airports by using a fuzzy geometric point of view according to the concept of unit-hypercube. By representing each airport as a point in the given reference metric space, the geometric distance among airports—which corresponds to a measure of similarity—has in fact an intrinsic fuzzy nature due to the airport specific characteristics. The proposed procedure has been applied to a test case concerning the Italian airport network and the obtained results are in line with expectations.

  13. A Geometric Approach For Fully Automatic Chromosome Segmentation

    CERN Document Server

    Minaee, Shervin; Khalaj, Babak Hossein

    2011-01-01

    Chromosome segmentation is a fundamental task in human chromosome analysis. Most of previous methods for separation between touching chromosomes require human intervention. In this paper, a geometry based method is used for automatic chromosome segmentation. This method can be divided into two phases. In the first phase, chromosome clusters are detected using three geometric criteria and in the second phase chromosome clusters are separated using a proper cut line. However, most earlier methods do not work well with chromosome clusters that contain more than two chromosomes. Our method, on the other hand, has a high efficiency in separation of chromosome clusters in such scenarios. Another advantage of the proposed method is that it can easily apply to any type of images such as binary images. This is due to the fact that the proposed scheme uses the geometric features of chromosomes which are independent of the type of images. The performance of the proposed scheme is demonstrated on a database containing to...

  14. An algebraic geometric approach to separation of variables

    CERN Document Server

    Schöbel, Konrad

    2015-01-01

    Konrad Schöbel aims to lay the foundations for a consequent algebraic geometric treatment of variable separation, which is one of the oldest and most powerful methods to construct exact solutions for the fundamental equations in classical and quantum physics. The present work reveals a surprising algebraic geometric structure behind the famous list of separation coordinates, bringing together a great range of mathematics and mathematical physics, from the late 19th century theory of separation of variables to modern moduli space theory, Stasheff polytopes and operads. "I am particularly impressed by his mastery of a variety of techniques and his ability to show clearly how they interact to produce his results.”   (Jim Stasheff)   Contents The Foundation: The Algebraic Integrability Conditions The Proof of Concept: A Complete Solution for the 3-Sphere The Generalisation: A Solution for Spheres of Arbitrary Dimension The Perspectives: Applications and Generalisations   Target Groups Scientists in the fie...

  15. Dynamics and Control of Humanoid Robots: A Geometrical Approach

    CERN Document Server

    Ivancevic, Vladimir G

    2011-01-01

    his paper reviews modern geometrical dynamics and control of humanoid robots. This general Lagrangian and Hamiltonian formalism starts with a proper definition of humanoid's configuration manifold, which is a set of all robot's active joint angles. Based on the `covariant force law', the general humanoid's dynamics and control are developed. Autonomous Lagrangian dynamics is formulated on the associated `humanoid velocity phase space', while autonomous Hamiltonian dynamics is formulated on the associated `humanoid momentum phase space'. Neural-like hierarchical humanoid control naturally follows this geometrical prescription. This purely rotational and autonomous dynamics and control is then generalized into the framework of modern non-autonomous biomechanics, defining the Hamiltonian fitness function. The paper concludes with several simulation examples. Keywords: Humanoid robots, Lagrangian and Hamiltonian formalisms, neural-like humanoid control, time-dependent biodynamics

  16. A geometric approach to quantum control in projective hilbert spaces

    Science.gov (United States)

    Pastorello, Davide

    2017-02-01

    A quantum theory in a finite-dimensional Hilbert space can be formulated as a proper geometric Hamiltonian theory as explained in [2, 3, 7, 9]. From this point of view a quantum system can be described within a classical-like framework where quantum dynamics is represented by a Hamiltonian flow in the phase space given by a projective Hilbert space. This paper is devoted to investigating how the notion of an accessibility algebra from classical control theory can be applied within the geometric Hamiltonian formulation of quantum mechanics to study controllability of a quantum system. A new characterization of quantum controllability in terms of Killing vector fields w.r.t. the Fubini-Study metric on projective space is also discussed.

  17. A protocol for the creation of useful geometric shape metrics illustrated with a newly derived geometric measure of leaf circularity1

    Science.gov (United States)

    Krieger, Jonathan D.

    2014-01-01

    • Premise of the study: I present a protocol for creating geometric leaf shape metrics to facilitate widespread application of geometric morphometric methods to leaf shape measurement. • Methods and Results: To quantify circularity, I created a novel shape metric in the form of the vector between a circle and a line, termed geometric circularity. Using leaves from 17 fern taxa, I performed a coordinate-point eigenshape analysis to empirically identify patterns of shape covariation. I then compared the geometric circularity metric to the empirically derived shape space and the standard metric, circularity shape factor. • Conclusions: The geometric circularity metric was consistent with empirical patterns of shape covariation and appeared more biologically meaningful than the standard approach, the circularity shape factor. The protocol described here has the potential to make geometric morphometrics more accessible to plant biologists by generalizing the approach to developing synthetic shape metrics based on classic, qualitative shape descriptors. PMID:25202647

  18. Margin Requirements and Portfolio Optimization: A Geometric Approach

    OpenAIRE

    Sheng Guo

    2014-01-01

    Using geometric illustrations, we investigate what implications of portfolio optimization in equilibrium can be generated by the simple mean-variance framework, under margin borrowing restrictions. First, we investigate the case of uniform marginability on all risky assets. It is shown that changing from unlimited borrowing to margin borrowing shifts the market portfolio to a riskier combination, accompanied by a higher risk premium and a lower price of risk. With the linear risk-return prefe...

  19. A Wave-Optics Approach to Paraxial Geometrical Laws Based on Continuity at Boundaries

    Science.gov (United States)

    Linares, J.; Nistal, M. C.

    2011-01-01

    We present a derivation of the paraxial geometrical laws starting from a wave-optics approach, in particular by using simple continuity conditions of paraxial spherical waves at boundaries (discontinuities) between optical media. Paraxial geometrical imaging and magnification laws, under refraction and reflection at boundaries, are derived for…

  20. A perturbation approach for geometrically nonlinear structural analysis using a general purpose finite element code

    NARCIS (Netherlands)

    Rahman, T.

    2009-01-01

    In this thesis, a finite element based perturbation approach is presented for geometrically nonlinear analysis of thin-walled structures. Geometrically nonlinear static and dynamic analyses are essential for this class of structures. Nowadays nonlinear analysis of thin-walled shell structures is oft

  1. Urbanisation and 3d Spatial - a Geometric Approach

    Science.gov (United States)

    Duncan, E. E.; Rahman, A. Abdul

    2013-09-01

    Urbanisation creates immense competition for space, this may be attributed to an increase in population owing to domestic and external tourism. Most cities are constantly exploring all avenues in maximising its limited space. Hence, urban or city authorities need to plan, expand and use such three dimensional (3D) space above, on and below the city space. Thus, difficulties in property ownership and the geometric representation of the 3D city space is a major challenge. This research, investigates the concept of representing a geometric topological 3D spatial model capable of representing 3D volume parcels for man-made constructions above and below the 3D surface volume parcel. A review of spatial data models suggests that the 3D TIN (TEN) model is significant and can be used as a unified model. The concepts, logical and physical models of 3D TIN for 3D volumes using tetrahedrons as the base geometry is presented and implemented to show man-made constructions above and below the surface parcel within a user friendly graphical interface. Concepts for 3D topology and 3D analysis are discussed. Simulations of this model for 3D cadastre are implemented. This model can be adopted by most countries to enhance and streamline geometric 3D property ownership for urban centres. 3D TIN concept for spatial modelling can be adopted for the LA_Spatial part of the Land Administration Domain Model (LADM) (ISO/TC211, 2012), this satisfies the concept of 3D volumes.

  2. A geometrical approach to two-dimensional Conformal Field Theory

    Science.gov (United States)

    Dijkgraaf, Robertus Henricus

    1989-09-01

    This thesis is organized in the following way. In Chapter 2 we will give a brief introduction to conformal field theory along the lines of standard quantum field theory, without any claims to originality. We introduce the important concepts of the stress-energy tensor, the Virasoro algebra, and primary fields. The general principles are demonstrated by fermionic and bosonic free field theories. This also allows us to discuss some general aspects of moduli spaces of CFT's. In particular, we describe in some detail the space of iiiequivalent toroidal comi)actificalions, giving examples of the quantum equivalences that we already mentioned. In Chapter 3 we will reconsider general quantum field theory from a more geometrical point of view, along the lines of the so-called operator formalism. Crucial to this approach will be the consideration of topology changing amplitudes. After a simple application to 2d topological theories, we proceed to give our second introduction to CFT, stressing the geometry behind it. In Chapter 4 the so-called rational conformal field theories are our object of study. These special CFT's have extended symmetries with only a finite number of representations. If an interpretation as non-linear sigma model exists, this extra symmetry can be seen as a kind of resonance effect due to the commensurability of the size of the string and the target space-time. The structure of rational CFT's is extremely rigid, and one of our results will be that the operator content of these models is—up to some discrete choices—completely determined by the symmetry algebra. The study of rational models is in its rigidity very analogous to finite group theory. In Chapter 5 this analogy is further pursued and substantiated. We will show how one can construct from general grounds rational conformal field theories from finite groups. These models are abstract versions of non-linear o-models describing string propagation on 'orbifoids.' An orbifold is a singular

  3. A new geometric approach to blind source separation of bounded sources

    Institute of Scientific and Technical Information of China (English)

    Jinlong Zhang; Guoxu Zhou; Zuyuan Yang; Xiaoxin Liao

    2009-01-01

    Based on the minimum-range approach, a new geometric approach is proposed to deal with blind source separation in this paper. The new approach is the batch mode of the original minimum-range approach. Compared with the original approach, the optimization algo-rithm of the proposed approach needs no parameters and is more efficient and reliable. In addition, the extension of minimum-range-based approaches is discussed. The simulations show the efficiency of the proposed approach.

  4. Clusters of Galaxies in a Weyl Geometric Approach to Gravity

    Directory of Open Access Journals (Sweden)

    Erhard Scholz

    2016-01-01

    Full Text Available A model for the dark halos of galaxy clusters, based on the Weyl geometric scalar tensor theory of gravity (WST with a MOND-like approximation, is proposed. It is uniquely determined by the baryonic mass distribution of hot gas and stars. A first heuristic check against empirical data for 19 clusters (2 of which are outliers, taken from the literature, shows encouraging results. Modulo a caveat resulting from different background theories (Einstein gravity plus ΛCDM versus WST, the total mass for 15 of the outlier reduced ensemble of 17 clusters seems to be predicted correctly (in the sense of overlapping 1σ error intervals.

  5. Modeling thermodynamic distance, curvature and fluctuations a geometric approach

    CERN Document Server

    Badescu, Viorel

    2016-01-01

    This textbook aims to briefly outline the main directions in which the geometrization of thermodynamics has been developed in the last decades. The textbook is accessible to people trained in thermal sciences but not necessarily with solid formation in mathematics. For this, in the first chapters a summary of the main mathematical concepts is made. In some sense, this makes the textbook self-consistent. The rest of the textbook consists of a collection of results previously obtained in this young branch of thermodynamics. The manner of presentation used throughout the textbook is adapted for ease of access of readers with education in natural and technical sciences.

  6. Probabilistically Perfect Cloning of Two Pure States: Geometric Approach

    Science.gov (United States)

    Yerokhin, V.; Shehu, A.; Feldman, E.; Bagan, E.; Bergou, J. A.

    2016-05-01

    We solve the long-standing problem of making n perfect clones from m copies of one of two known pure states with minimum failure probability in the general case where the known states have arbitrary a priori probabilities. The solution emerges from a geometric formulation of the problem. This formulation reveals that cloning converges to state discrimination followed by state preparation as the number of clones goes to infinity. The convergence exhibits a phenomenon analogous to a second-order symmetry-breaking phase transition.

  7. Algebro-geometric approach in the theory of integrable hydrodynamic type systems

    OpenAIRE

    Pavlov, Maxim V.

    2006-01-01

    The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. This method is significantly simplified for so-called symmetric hydrodynamic type systems. Plenty interesting and physically motivated examples are investigated.

  8. Observer-based FDI for Gain Fault Detection in Ship Propulsion Benchmark:a Geometric Approach

    OpenAIRE

    Lootsma, T.F.; Izadi-Zamanabadi, Roozbeh; Nijmeijer, H.

    2001-01-01

    A geometric approach for input-affine nonlinear systems is briefly described and then applied to a ship propulsion benchmark. The obtained results are used to design a diagnostic nonlinear observer for successful FDI of the diesel engine gain fault

  9. A geometric approach to the precession of compact binaries

    CERN Document Server

    Boyle, Michael; Pfeiffer, Harald P

    2011-01-01

    We propose a geometrical method to define a preferred reference frame for precessing binary systems. This minimal-rotation frame is aligned with the angular-momentum axis and fixes the rotation about that axis up to a constant angle, resulting in an essentially invariant frame. Gravitational waveforms decomposed in this frame are similarly invariant under rotations of the inertial frame and exhibit relatively smoothly varying phase. By contrast, earlier prescriptions for radiation-aligned frames induce extraneous features in the gravitational-wave phase which depend on the orientation of the inertial frame, which leads to fluctuations in the frequency and may compound to many gravitational-wave cycles. We suggest that the minimal-rotation frame provides a simplified framework for post-Newtonian approximations of precessing systems and describe the construction of analytical/numerical hybrid waveforms for such systems.

  10. A Geometric Approach for Multi-Degree Spline

    Institute of Scientific and Technical Information of China (English)

    Xin Li; Zhang-Jin Huang; Zhao Liu

    2012-01-01

    Multi-degree spline (MD-spline for short) is a generalization of B-spline which comprises of polynomial segments of various degrees.The present paper provides a new definition for MD-spline curves in a geometric intuitive way based on an efficient and simple evaluation algorithm.MD-spline curves maintain various desirable properties of B-spline curves,such as convex hull,local support and variation diminishing properties.They can also be refined exactly with knot insertion.The continuity between two adjacent segments with different degrees is at least C1 and that between two adjacent segments of same degrees d is Cd-1.Benefited by the exact refinement algorithm,we also provide several operators for MD-spline curves,such as converting each curve segment into Bézier form,an efficient merging algorithm and a new curve subdivision scheme which allows different degrees for each segment.

  11. Approximate Approaches to Geometric Corrections of High Resolution Satellite Imagery

    Institute of Scientific and Technical Information of China (English)

    SHI Wenzhong; Ahmed Shaker

    2004-01-01

    The exploitation of different non-rigorous mathematical models as opposed to the satellite rigorous models is discussed for geometric corrections and topographic/thematic maps production of high-resolution satellite imagery (HRSI). Furthermore, this paper focuses on the effects of the number of GCPs and the terrain elevation difference within the area covered by the images on the obtained ground points accuracy. From the research, it is obviously found that non-rigorous orientation and triangulation models can be used successfully in most cases for 2D rectification and 3D ground points determination without a camera model or the satellite ephemeris data. In addition, the accuracy up to the sub-pixel level in plane and about one pixel in elevation can be achieved with a modest number of GCPs.

  12. An Intuitive Approach to Geometric Continuity for Parametric Curves and Surfaces (Extended Abstract)

    Science.gov (United States)

    Derose, T. D.; Barsky, B. A.

    1985-01-01

    The notion of geometric continuity is extended to an arbitrary order for curves and surfaces, and an intuitive development of constraints equations is presented that are necessary for it. The constraints result from a direct application of the univariate chain rule for curves, and the bivariate chain rule for surfaces. The constraints provide for the introduction of quantities known as shape parameters. The approach taken is important for several reasons: First, it generalizes geometric continuity to arbitrary order for both curves and surfaces. Second, it shows the fundamental connection between geometric continuity of curves and geometric continuity of surfaces. Third, due to the chain rule derivation, constraints of any order can be determined more easily than derivations based exclusively on geometric measures.

  13. On the Robot Singularity: A Novel Geometric Approach

    Directory of Open Access Journals (Sweden)

    Man Bok Hong

    2012-11-01

    Full Text Available This paper addresses a novel geometric analysis method of the singularity and kinestatic characteristics of robots. For non‐redundant robots, there exist two uniquely determined Jacobians ‐ the screw‐based Jacobian and the reciprocal Jacobian. Here, it is shown that if some of the reciprocal products between the column screws of the two Jacobians are close to zero, the robot is in the vicinity of a singular configuration and the corresponding columns of the Jacobian are involved in the singularity. From this observation, an invariant measure of closeness to a singularity is presented using the reciprocal products. Furthermore, by considering the reciprocal products between the actuated joint screws and column screws of the Jacobian, this measure is extended so that the concept of the kinestatic characterization index is presented for parallel robots. Since it is defined as the ratio of reciprocal products from the uniqueness of the two Jacobians, it represents a unique invariant characteristic of robots. From the singularity analyses of the planar 4‐bar linkage and the 3‐DOF parallel manipulator with PRS‐serial chains, the validity of the proposed index is examined and the concept of a kinestatically balanced configuration is introduced as well.

  14. Geometric approach to chaos in the classical dynamics of Abelian lattice gauge theory

    Energy Technology Data Exchange (ETDEWEB)

    Casetti, Lapo [Istituto Nazionale per la Fisica della Materia (INFM), Unita di Ricerca del Politecnico di Torino, Dipartimento di Fisica, Politecnico di Torino, Turin (Italy); Gatto, Raoul [Departement de Physique Theorique, Universite de Geneve, Geneva (Switzerland); Pettini, Marco [Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, Florence (Italy)

    1999-04-23

    A Riemannian geometrization of dynamics is used to study chaoticity in the classical Hamiltonian dynamics of a U(1) lattice gauge theory. This approach allows one to obtain analytical estimates of the largest Lyapunov exponent in terms of time averages of geometric quantities. These estimates are compared with the results of numerical simulations, and turn out to be very close to the values extrapolated for very large lattice sizes even when the geometric quantities are computed using small lattices. The scaling of the Lyapunov exponent {lambda} with the energy density {epsilon} is found to be well described by the law {lambda}{proportional_to}{epsilon}{sup 2}. (author)

  15. Geometric approach to chaos in the classical dynamics of abelian lattice gauge theory

    CERN Document Server

    Casetti, L; Pettini, M; Casetti, Lapo; Gatto, Raoul; Pettini, Marco

    1998-01-01

    A Riemannian geometrization of dynamics is used to study chaoticity in the classical Hamiltonian dynamics of a U(1) lattice gauge theory. This approach allows one to obtain analytical estimates of the largest Lyapunov exponent in terms of time averages of geometric quantities. These estimates are compared with the results of numerical simulations, and turn out to be very close to the values extrapolated for very large lattice sizes even when the geometric quantities are computed using small lattices. The scaling of the Lyapunov exponent with the energy density is found to be well described by a quadratic power law.

  16. Comparison of the morphometric features of the left and right horse kidneys: a stereological approach.

    Science.gov (United States)

    Bolat, D; Bahar, S; Tipirdamaz, S; Selcuk, M L

    2013-12-01

    The aims of this study were to determine the total volume of the horse kidney and volume fractions of its functional subcomponents (cortex, medulla, renal pelvis) using stereological methods and investigate any possible difference in the functional subcomponents of the right and left kidneys that may arise from differences in shape. The study was carried out on the kidneys of 5 horses of different breed and sex. The weight of the kidneys was measured by a digital scale, and kidney volume was calculated by Archimedes' principle. Total kidney volume and volume fractions of subcomponents of the right and left kidneys were estimated by the Cavalieri's principle. The weights of the right and left kidneys were 550 ± 25 g and 585 ± 23 g, respectively. The volumes of the right and left kidneys estimated using the Cavalieri method were 542 ± 46 ml and 581 ± 29 ml. The relative organ weight of the kidneys was calculated as 1:330. The densities of the right and left kidneys were determined to be 1.01 and 1.00, respectively. The mean volume fractions of the cortex, medulla and renal pelvis were determined as 55.6, 42.7 and 1.7 in both kidneys. No statistically significant difference existed between morphometric data pertaining to the right and left kidneys (P > 0.05). To determine precisely whether differences in shape cause any difference in the functional subcomponents of the right and left kidneys requires further investigation of differences in the number of microscopically functional unit of the kidney such as renal glomeruli and nephrons.

  17. The utility of captive animals in actualistic research: A geometric morphometric exploration of the tooth row of Alligator mississippiensis suggesting ecophenotypic influences and functional constraints.

    Science.gov (United States)

    Drumheller, Stephanie K; Wilberg, Eric W; Sadleir, Rudyard W

    2016-07-01

    Captive broad snouted crocodylians are generally thought to have wider, shorter rostra than their wild counterparts. Interpreted to reflect morphological change in response to the conditions of captivity, this qualitative pattern could affect the utility of these animals in a variety of fields of research. However, due to relative ease of access and availability of life history data, captive animals are often utilized in actualistic research. Thus, this issue should be addressed in more detail. Here we explore snout shape variation between captive and wild members of Alligator mississippiensis using two-dimensional (2D) morphometric techniques. Several landmark schemesare used to assess the utility of different aspects of morphology in distinguishing the groups. While statistical analyses consistently differentiated between the groups, the area of morphospace occupied by wild members of A. mississippiensis generally overlapped with the larger area encompassing the captive specimens. This indicates that the captive condition is not as uniform as previously thought and instead encompasses a large spectrum of morphologies, ranging from the stereotypical broad, shortened snouts to outlines that are indistinguishable from the wild morphotype. These results align well with the interpretation that this change reflects an extreme example of ecophenotypy, since ranched, farmed, or zoo organisms are held in an array of enclosures, ranging from indoor, climate controlled pens to outdoor, more natural areas. This variation in environments should be reflected in different reactions to the animals' surroundings, resulting in a broad spectrum of morphotypes. While wild specimens are still preferred, especially for fine scale analyses, these results indicate that not all captive members of A. mississippiensis exhibit the extreme morphological alterations often cited in the literature. Weighing the conditions in which the animals are held and exploring the possibility of

  18. A geometric approach to multi-view compressive imaging

    Science.gov (United States)

    Park, Jae Young; Wakin, Michael B.

    2012-12-01

    In this paper, we consider multi-view imaging problems in which an ensemble of cameras collect images describing a common scene. To simplify the acquisition and encoding of these images, we study the effectiveness of non-collaborative compressive sensing encoding schemes wherein each sensor directly and independently compresses its image using randomized measurements. After these measurements and also perhaps the camera positions are transmitted to a central node, the key to an accurate reconstruction is to fully exploit the joint correlation among the signal ensemble. To capture such correlations, we propose a geometric modeling framework in which the image ensemble is treated as a sampling of points from a low-dimensional manifold in the ambient signal space. Building on results that guarantee stable embeddings of manifolds under random measurements, we propose a "manifold lifting" algorithm for recovering the ensemble that can operate even without knowledge of the camera positions. We divide our discussion into two scenarios, the near-field and far-field cases, and describe how the manifold lifting algorithm could be applied to these scenarios. At the end of this paper, we present an in-depth case study of a far-field imaging scenario, where the aim is to reconstruct an ensemble of satellite images taken from different positions with limited but overlapping fields of view. In this case study, we demonstrate the impressive power of random measurements to capture single- and multi-image structure without explicitly searching for it, as the randomized measurement encoding in conjunction with the proposed manifold lifting algorithm can even outperform image-by-image transform coding.

  19. Matrix Operator Approach to Quantum Evolution Operator and Geometric Phase

    CERN Document Server

    Kim, Sang Pyo; Soh, Kwang Sup

    2012-01-01

    The Moody-Shapere-Wilczek's adiabatic effective Hamiltonian and Lagrangian method is developed further into the matrix effective Hamiltonian (MEH) and Lagrangian (MEL) approach to a parameter-dependent quantum system. The matrix operator approach formulated in the product integral (PI) provides not only a method to find wave function efficiently in the MEH approach but also higher order corrections to the effective action systematically in the MEL approach, a la the Magnus expansion and the Kubo's cumulant expansion. A coupled quantum system of a light particle of harmonic oscillator is worked out, and as a by-product a new kind of gauge potential (Berry's connection) is found even for nondegenerate case (real eigenfunctions). Moreover, in the PI formulation the holonomy of the induced gauge potential is related to the Schlesinger's exact formula for the gauge field tensor. A superadiabatic expansion is also constructed and a generalized Dykhne formula, depending on the contour integrals of homotopy class of ...

  20. A Simple Geometric Approach to Approximating the Gini Coefficient

    Science.gov (United States)

    Kasper, Hirschel; Golden, John

    2008-01-01

    The author shows how a quick approximation of the Lorenz curve's Gini coefficient can be calculated empirically using numerical data presented in cumulative income quintiles. When the technique here was used to estimate 621 income quintile/Gini coefficient observations from the Deninger and Squire/World Bank data set, this approach performed…

  1. Geometric approaches to the thermodynamics of black holes

    CERN Document Server

    Gruber, Christine; Quevedo, Hernando

    2016-01-01

    In this summary, we present the main topics of the talks presented in the parallel session "Black holes - 5" of the 14th Marcel Grossmann Meeting held in Rome, Italy in July 2015. We first present a short review of the main approaches used to understand thermodynamics by using differential geometry. Then, we present a brief summary of each presentation, including some general remarks and comments.

  2. Symmetries of stochastic differential equations: A geometric approach

    Energy Technology Data Exchange (ETDEWEB)

    De Vecchi, Francesco C., E-mail: francesco.devecchi@unimi.it; Ugolini, Stefania, E-mail: stefania.ugolini@unimi.it [Dipartimento di Matematica, Università degli Studi di Milano, via Saldini 50, Milano (Italy); Morando, Paola, E-mail: paola.morando@unimi.it [DISAA, Università degli Studi di Milano, via Celoria 2, Milano (Italy)

    2016-06-15

    A new notion of stochastic transformation is proposed and applied to the study of both weak and strong symmetries of stochastic differential equations (SDEs). The correspondence between an algebra of weak symmetries for a given SDE and an algebra of strong symmetries for a modified SDE is proved under suitable regularity assumptions. This general approach is applied to a stochastic version of a two dimensional symmetric ordinary differential equation and to the case of two dimensional Brownian motion.

  3. A new approach to compensate the geometric distortion in the synthetic aperture ultrasonic imaging system.

    Science.gov (United States)

    He, Xiaonian; Liu, Weixiang; Chen, Siping; Qin, Zhengdi

    2015-01-01

    In the field of ultrasonic imaging technology, the problem of geometric distortion is often encountered, especially in the ultrasonic near-field. In this study, a new approach is proposed to compensate for geometric distortion in the synthetic aperture ultrasonic imaging system. This approach is based on the synthetic aperture ultrasonic holographic B-scan (UHB) imaging system, which is a combination of ultrasonic holography based on the backward propagation principle and the conventional B-scan technique. To solve the geometric distortion problem, the operation of the spatial compression and resampling in the frequency domain are introduced. The main advantage of the approach is that the real holographic value can be calculated without distortion by using the spatial interpolation function after the spatial frequency compression. After the compensation for geometric distortion is performed, the synthetic aperture technique based on the backward propagation principle is then applied in the process of the two-dimensional numerical imaging reconstruction. Both the simulation and measurement experiment show that the approach is promising. The geometric distortion that is dependent on the wave front angle can be effectively compensated. The spatial resolution is practically uniform throughout the depth range and close to the theoretical limit in the experiments.

  4. A wave-optics approach to paraxial geometrical laws based on continuity at boundaries

    Science.gov (United States)

    Liñares, J.; Nistal, M. C.

    2011-09-01

    We present a derivation of the paraxial geometrical laws starting from a wave-optics approach, in particular by using simple continuity conditions of paraxial spherical waves at boundaries (discontinuities) between optical media. Paraxial geometrical imaging and magnification laws, under refraction and reflection at boundaries, are derived for several instructive cases and without using Fresnel diffraction theory. The primary aim is to provide a complementary insight into the standard axiomatic approach of paraxial geometrical optics and likewise to allow the introduction of some wave imaging concepts, such as the transmittance function, with a notable didactic interest for advanced subjects such as Fourier optics. This approach provides a more homogeneous vision of classical optics in which the use of the optical field continuity conditions at a boundary is a usual requirement as is clearly seen, for example, in the case of the derivation of Fresnel formulas. The work is particularly intended for university physics teachers and pregraduate and first year postgraduate students.

  5. 沂源人牙冠的几何形态学研究%Geometric and Morphometric Analysis of Middle Pleistocene Hominin Teeth from Yiyuan, Shandong Province

    Institute of Scientific and Technical Information of China (English)

    孙承凯; 周蜜; 邢松

    2011-01-01

    Morphometric analysis of the crowns of six teeth from the Yiyuan site were compared with those of Homo erectus, archaic and late Homo sapiens from Asia, Australopithecus, African early Homo and recent Chinese. The present study shows that the Yiyuan teeth retain some primitive traits, including their trapezoidal outline shapes of the upper premolars and the straight mesial outline of the first upper molar. Other features are apomorphic, as manifested in the extent to which outline of p3 buccal cusp expands mesially and distally, the outline shape of the P4,which is close to that of the recent Chinese, the relatively large paracone size compared to the metacone in M1 , and the roundness of the buccal outline and relatively restricted metaconid of M1. Fossil teeth of early and middle Pleistocene Chinese exhibit many similarities to each other,with no obvious differences being shown, therefore Chinese Homo erectus and archaic Homo sapiens could be treated as a sample group. The teeth from Yiyuan could also be placed in this group, however these teeth are quite “evolved” compared with other sample members. It is noteworthy that M1 and M1 have a very large value of BL/MD, which surpasses each of corresponding specimens used in present study and may be meaningful in interpreting evolutionary progress.%采用形态测量分析方法对上世纪80年代发现于山东沂源的6枚人类牙齿化石齿冠外轮廓形状进行了研究,并与亚洲直立人、早期智人、晚期智人、南方古猿、非洲早期人属以及现代人进行了对比.本文发现:沂源人既保留了部分原始特征,也表现出许多进步特征.颊侧尖基底轮廓原始特征主要表现在P3和P4近似蚕豆形的外轮廓及M1近中轮廓线的平直;进步特征主要体现在:P3向近远中方向的明显扩展、颊侧尖向颊侧的突出程度减弱,P4外轮廓形状处于现代人分布范围的边缘,M1前后尖比例增大,M1颊侧外轮廓的圆隆以及下后尖的

  6. A Geometric Approach for Robotic Arm Kinematics with Hardware Design, Electrical Design, and Implementation

    Directory of Open Access Journals (Sweden)

    Kurt E. Clothier

    2010-01-01

    Full Text Available This paper presents a geometric approach to solve the unknown joint angles required for the autonomous positioning of a robotic arm. A plethora of complex mathematical processes is reduced using basic trigonometric in the modeling of the robotic arm. This modeling and analysis approach is tested using a five-degree-of-freedom arm with a gripper style end effector mounted to an iRobot Create mobile platform. The geometric method is easily modifiable for similar robotic system architectures and provides the capability of local autonomy to a system which is very difficult to manually control.

  7. A new approach to estimate the geometrical factors, solid angle approximation, geometrical efficiency and their use in basic interaction cross section measurements

    CERN Document Server

    Rao, D V; Brunetti, A; Gigante, G E; Takeda, T; Itai, Y; Akatsuka, T

    2002-01-01

    A new approach is developed to estimate the geometrical factors, solid angle approximation and geometrical efficiency for a system with experimental arrangements using X-ray tube and secondary target as an excitation source in order to produce the nearly monoenergetic K alpha radiation to excite the sample. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work. (authors)

  8. Scaling violations Connections between elastic and inelastic hadron scattering in a geometrical approach

    CERN Document Server

    Beggio, P C; Valin, P

    2000-01-01

    Starting from a short range expansion of the inelastic overlap function, capable of describing quite well the elastic pp and $\\bar{p}p$ scattering data, we obtain extensions to the inelastic channel, through unitarity and an impact parameter approach. Based on geometrical arguments we infer some characteristics of the elementary hadronic process and this allows an excellent description of the inclusive multiplicity distributions in $pp$ and $\\bar{p}p$ collisions. With this approach we quantitatively correlate the violations of both geometrical and KNO scaling in an analytical way. The physical picture from both channels is that the geometrical evolution of the hadronic constituents is principally reponsible for the energy dependence of the physical quantities rather than the dynamical (elementary) interaction itself.

  9. Determination of a novel size proxy in comparative morphometrics

    Directory of Open Access Journals (Sweden)

    Andrew Gallagher

    2015-09-01

    Full Text Available Absolute size is a critical determinant of organismal biology, yet there exists no real consensus as to what particular metric of ‘size’ is empirically valid in assessments of extinct mammalian taxa. The methodological approach of JE Mosimann has found extensive favour in ‘size correction’ in comparative morphometrics, but not ‘size prediction’ in palaeontology and palaeobiology. Analyses of five distinct mammalian data sets confirm that a novel size variate (GMSize derived from k=8 dimensions of the postcranial skeleton effectively satisfies all expectations of the Jolicoeur–Mosimann theorem of univariate and multivariate size. On the basis of strong parametric correlations between the k=8 variates and between scores derived from the first principal component and geometric mean size (GMSize in all series, this novel size variable has considerable utility in comparative vertebrate morphometrics and palaeobiology as an appropriate descriptor of individual size in extant and extinct taxa.

  10. A Geometric Approach to Diagnosis Applied to A Ship Propulsion Problem

    DEFF Research Database (Denmark)

    Lootsma, T.F.; Izadi-Zamanabadi, Roozbeh; Nijmeijer, H.

    A geometric approach to FDI diagnosis for input-affine nonlinear systems is briefly described and applied to a ship propulsion benchmark. The analysis method is used to examine the possibility of detecting and isolating predefined faults in the system. The considered faults cover sensor, actuator...

  11. Extended Endoscopic Endonasal Approaches for Cerebral Aneurysms: Anatomical, Virtual Reality and Morphometric Study

    OpenAIRE

    Alberto Di Somma; Matteo de Notaris; Vita Stagno; Luis Serra; Joaquim Enseñat; Isam Alobid; Joan San Molina; Joan Berenguer; Paolo Cappabianca; Alberto Prats-Galino

    2014-01-01

    Introduction. The purpose of the present contribution is to perform a detailed anatomic and virtual reality three-dimensional stereoscopic study in order to test the effectiveness of the extended endoscopic endonasal approaches for selected anterior and posterior circulation aneurysms. Methods. The study was divided in two main steps: (1) simulation step, using a dedicated Virtual Reality System (Dextroscope, Volume Interactions); (2) dissection step, in which the feasibility to reach specifi...

  12. A METHODOLOGICAL APPROACH TO THE CHARACTERIZATION OF BRAIN GLIOMAS, BY MEANS OF SEMI-AUTOMATIC MORPHOMETRIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    Artur Dawid Surowka

    2014-05-01

    Full Text Available The aims of this paper were to present a reliable morphometric procedure for glioma analysis for preliminary prognosis and to develop a semi-automatic procedure that is easy to use. The data presented are important to the extent that they verify the reliability of the results by showing that they are consistent with the findings from more complicated automatic analytical tools. The objects for analysis were digital images of haematoxylin-eosin stained glioma samples. The overall analysis consisted of digital image analysis and the determination of morphometric parameters. Interestingly, an increase in the mean values of aspect ratio with increasing malignancy grade was found. Moreover, the morphometric parameters in relation to the histological origin of gliomas were examined and it was found that, the cellular nuclei of glioblastoma multiforme reveal the biggest mean values of aspect ratio compared with other gliomas.

  13. Extended Endoscopic Endonasal Approaches for Cerebral Aneurysms: Anatomical, Virtual Reality and Morphometric Study

    Directory of Open Access Journals (Sweden)

    Alberto Di Somma

    2014-01-01

    Full Text Available Introduction. The purpose of the present contribution is to perform a detailed anatomic and virtual reality three-dimensional stereoscopic study in order to test the effectiveness of the extended endoscopic endonasal approaches for selected anterior and posterior circulation aneurysms. Methods. The study was divided in two main steps: (1 simulation step, using a dedicated Virtual Reality System (Dextroscope, Volume Interactions; (2 dissection step, in which the feasibility to reach specific vascular territory via the nose was verified in the anatomical laboratory. Results. Good visualization and proximal and distal vascular control of the main midline anterior and posterior circulation territory were achieved during the simulation step as well as in the dissection step (anterior communicating complex, internal carotid, ophthalmic, superior hypophyseal, posterior cerebral and posterior communicating, basilar, superior cerebellar, anterior inferior cerebellar, vertebral, and posterior inferior cerebellar arteries. Conclusion. The present contribution is intended as strictly anatomic study in which we highlighted some specific anterior and posterior circulation aneurysms that can be reached via the nose. For clinical applications of these approaches, some relevant complications, mainly related to the endonasal route, such as proximal and distal vascular control, major arterial bleeding, postoperative cerebrospinal fluid leak, and olfactory disturbances must be considered.

  14. Geometric Morphometric Study of Two Homozygous Color Strains of the Golden Apple Snail Pomacea canaliculata (Caenogastropoda:Ampullariidae)%2个纯合体色品系大瓶螺的几何形态测量学研究

    Institute of Scientific and Technical Information of China (English)

    来益同; 沈华; 张奕祥; 吴岷

    2016-01-01

    为了探究大瓶螺(Pomacea canaliculata)体色、性别与贝壳形态之间的关系,运用几何形态测量学方法,对来自于人工繁育的F5纯合体色品系37只深褐色个体(26♀♀,11♂♂)、34只黄色个体(14♀♀,20♂♂)贝壳的正壳口观、壳口观、壳顶观进行地标标点,获得贝壳的形态信息。运用主成分分析和典型变量分析,检测出不同体色、性别个体间的差异。通过各个标点对于相对扭曲的贡献率,探究其形态变化趋势。主成分分析结果表明,不同体色个体的贝壳形态存在着明显差异,正壳口观较壳口观及壳顶观更能体现贝壳差异;而不同体色的贝壳差异均不及相同体色不同性别个体间贝壳的差异。典型变量分析结果通过普氏距离和马氏距离得以反映,所有组别间的马氏距离均有显著性差异,而普氏距离仅在壳顶观的深褐色和黄色雌螺间以及壳顶观的深褐色和黄色雄螺间无显著差异;对正壳口观各标点对相对扭曲的贡献率分析表明,贝壳形态的变化主要集中在壳口上半部,支持不同体色和性别的大瓶螺在贝壳形态上存在显著差异的结论。发掘大瓶螺中所存在的这些差异对探究不同体色个体的适应性差异提供了重要参考,也表明几何形态测量学可以作为贝壳形态研究的有效方法应用于贝类形态学和种群分析等研究中。%Pomacea canaliculata,an invasive freshwater gastropod,has become an increasingly serious pest snail in China.The shell shape of Pomacea canaliculata is thought to be determined by both genetic and environmental conditions.In this study,we performed geometric morphometric analysis to detect possible shape differentiations in shells of different colors and both sexes of the golden apple snail.Mature P.canaliculata individuals were used for this study,all homozygous at the loci associated to shell coloration.The snails

  15. Geometric Form Drawing: A Perceptual-Motor Approach to Preventive Remediation (The Steiner Approach)

    Science.gov (United States)

    Ogletree, Earl J.

    1975-01-01

    Provided is a rationale for geometric form drawing developed by Rudolf Steiner as a tool to develop motor coordination, perceptual skills, and cognition for mentally retarded and perceptually handicapped children. (Author/CL)

  16. A new set of basis functions for the discrete geometric approach

    Science.gov (United States)

    Codecasa, Lorenzo; Specogna, Ruben; Trevisan, Francesco

    2010-09-01

    By exploiting the geometric structure behind Maxwell's equations, the so called discrete geometric approach allows to translate the physical laws of electromagnetism into discrete relations, involving circulations and fluxes associated with the geometric elements of a pair of interlocked grids: the primal grid and the dual grid. To form a finite dimensional system of equations, discrete counterparts of the constitutive relations must be introduced in addition. They are referred to as constitutive matrices which must comply with precise properties (symmetry, positive definiteness, consistency) in order to guarantee the stability and consistency of the overall finite dimensional system of equations. The aim of this work is to introduce a general and efficient set of vector functions associated with the edges and faces of a polyhedral primal grids or of a dual grid obtained from the barycentric subdivision of the boundary of the primal grid; these vector functions comply with precise specifications which allow to construct stable and consistent discrete constitutive equations for the discrete geometric approach in the framework of an energetic method.

  17. The morphometrics of "masculinity" in human faces.

    Science.gov (United States)

    Mitteroecker, Philipp; Windhager, Sonja; Müller, Gerd B; Schaefer, Katrin

    2015-01-01

    In studies of social inference and human mate preference, a wide but inconsistent array of tools for computing facial masculinity has been devised. Several of these approaches implicitly assumed that the individual expression of sexually dimorphic shape features, which we refer to as maleness, resembles facial shape features perceived as masculine. We outline a morphometric strategy for estimating separately the face shape patterns that underlie perceived masculinity and maleness, and for computing individual scores for these shape patterns. We further show how faces with different degrees of masculinity or maleness can be constructed in a geometric morphometric framework. In an application of these methods to a set of human facial photographs, we found that shape features typically perceived as masculine are wide faces with a wide inter-orbital distance, a wide nose, thin lips, and a large and massive lower face. The individual expressions of this combination of shape features--the masculinity shape scores--were the best predictor of rated masculinity among the compared methods (r = 0.5). The shape features perceived as masculine only partly resembled the average face shape difference between males and females (sexual dimorphism). Discriminant functions and Procrustes distances to the female mean shape were poor predictors of perceived masculinity.

  18. The morphometrics of "masculinity" in human faces.

    Directory of Open Access Journals (Sweden)

    Philipp Mitteroecker

    Full Text Available In studies of social inference and human mate preference, a wide but inconsistent array of tools for computing facial masculinity has been devised. Several of these approaches implicitly assumed that the individual expression of sexually dimorphic shape features, which we refer to as maleness, resembles facial shape features perceived as masculine. We outline a morphometric strategy for estimating separately the face shape patterns that underlie perceived masculinity and maleness, and for computing individual scores for these shape patterns. We further show how faces with different degrees of masculinity or maleness can be constructed in a geometric morphometric framework. In an application of these methods to a set of human facial photographs, we found that shape features typically perceived as masculine are wide faces with a wide inter-orbital distance, a wide nose, thin lips, and a large and massive lower face. The individual expressions of this combination of shape features--the masculinity shape scores--were the best predictor of rated masculinity among the compared methods (r = 0.5. The shape features perceived as masculine only partly resembled the average face shape difference between males and females (sexual dimorphism. Discriminant functions and Procrustes distances to the female mean shape were poor predictors of perceived masculinity.

  19. Present State of the Art of Composite Fabric Forming: Geometrical and Mechanical Approaches

    Directory of Open Access Journals (Sweden)

    Abel Cherouat

    2009-11-01

    Full Text Available Continuous fibre reinforced composites are now firmly established engineering materials for the manufacture of components in the automotive and aerospace industries. In this respect, composite fabrics provide flexibility in the design manufacture. The ability to define the ply shapes and material orientation has allowed engineers to optimize the composite properties of the parts. The formulation of new numerical models for the simulation of the composite forming processes must allow for reduction in the delay in manufacturing and an optimization of costs in an integrated design approach. We propose two approaches to simulate the deformation of woven fabrics: geometrical and mechanical approaches.

  20. Fuzzy Decision-Making Approach in Geometric Programming for a Single Item EOQ Model

    Directory of Open Access Journals (Sweden)

    Monalisha Pattnaik

    2015-06-01

    Full Text Available Background and methods: Fuzzy decision-making approach is allowed in geometric programming for a single item EOQ model with dynamic ordering cost and demand-dependent unit cost. The setup cost varies with the quantity produced/purchased and the modification of objective function with storage area in the presence of imprecisely estimated parameters are investigated.  It incorporates all concepts of a fuzzy arithmetic approach, the quantity ordered, and demand per unit compares both fuzzy geometric programming technique and other models for linear membership functions.  Results and conclusions: Investigation of the properties of an optimal solution allows developing an algorithm whose validity is illustrated through an example problem and the results discu ssed. Sensitivity analysis of the optimal solution is also studied with respect to changes in different parameter values.  

  1. A Geometric Approach to the Kronecker Problem I: The Two Row Case

    Indian Academy of Sciences (India)

    Bharat Adsul; K V Subrahmanyam

    2008-05-01

    Given two irreducible representations , of the symmetric group $S_d$, the Kronecker problem is to find an explicit rule, giving the multiplicity of an irreducible representation, , of $S_d$, in the tensor product of and . We propose a geometric approach to investigate this problem. We demonstrate its effectiveness by obtaining explicit formulas for the tensor product multiplicities, when the irreducible representations are parameterized by partitions with at most two rows.

  2. Geometric Approaches for Reducing Burr Formation in Planar Milling by Avoiding Tool Exits

    OpenAIRE

    Dornfeld, David; Chu, Chih-Hsing

    2005-01-01

    One of the most effective methods for reducing milling exit burrs is to prevent the tool from exiting the workpiece. Exit here refers the condition in which a cutting edge is moving out of the workpiece while removing material. Only entrance burrs can occur under this circumstance, which are usually considered burr-free. This study proposes a set of geometric algorithms for avoiding tool exits in planar milling. Two distinct approaches are developed for tool path planning of 2-D polygons. The...

  3. Polishing mechanism of light-initiated dental composite: Geometric optics approach.

    Science.gov (United States)

    Chiang, Yu-Chih; Lai, Eddie Hsiang-Hua; Kunzelmann, Karl-Heinz

    2016-12-01

    For light-initiated dental hybrid composites, reinforcing particles are much stiffer than the matrix, which makes the surface rugged after inadequate polish and favors bacterial adhesion and biofilm redevelopment. The aim of the study was to investigate the polishing mechanism via the geometric optics approach. We defined the polishing abilities of six instruments using the obtained gloss values through the geometric optics approach (micro-Tri-gloss with 20°, 60°, and 85° measurement angles). The surface texture was validated using a field emission scanning electron microscope (FE-SEM). Based on the gloss values, we sorted polishing tools into three abrasive levels, and proposed polishing sequences to test the hypothesis that similar abrasive levels would leave equivalent gloss levels on dental composites. The three proposed, tested polishing sequences included: S1, Sof-Lex XT coarse disc, Sof-Lex XT fine disc, and OccluBrush; S2, Sof-Lex XT coarse disc, Prisma Gloss polishing paste, and OccluBrush; and S3, Sof-Lex XT coarse disc, Enhance finishing cups, and OccluBrush. S1 demonstrated significantly higher surface gloss than the other procedures (p geometric optic approach is an efficient and nondestructive method to characterize the polished surface of dental composites. Copyright © 2015. Published by Elsevier B.V.

  4. Identification of Bacillus strains by MALDI TOF MS using geometric approach

    Science.gov (United States)

    Starostin, Konstantin V.; Demidov, Evgeny A.; Bryanskaya, Alla V.; Efimov, Vadim M.; Rozanov, Alexey S.; Peltek, Sergey E.

    2015-01-01

    Microorganism identification by MALDI TOF mass-spectrometry is based on the comparison of the mass spectrum of the studied organism with those of reference strains. It is a rapid and reliable method. However, commercial databases and programs are mostly designed for identification of clinically important strains and can be used only for particular mass spectrometer models. The need for open platforms and reference databases is obvious. In this study we describe a geometric approach for microorganism identification by mass spectra and demonstrate its capabilities by analyzing 24 strains belonging to the Bacillus pumilus group. This method is based on representing mass spectra as points on a multidimensional space, which allows us to use geometric distances to compare the spectra. Delimitation of microorganisms performed by geometric approach correlates well with the results of molecular phylogenetic analysis and clustering using Biotyper 3.1. All three methods used allowed us to reliably divide the strains into two groups corresponding to closely related species, Bacillus pumilus and Bacillus altitudinis. The method developed by us will be implemented in a Web interface designed for using open reference databases for microorganism identification. The data is available at http://www.bionet.nsc.ru/mbl/database/database.html. PMID:26592761

  5. Identification of Bacillus strains by MALDI TOF MS using geometric approach

    Science.gov (United States)

    Starostin, Konstantin V.; Demidov, Evgeny A.; Bryanskaya, Alla V.; Efimov, Vadim M.; Rozanov, Alexey S.; Peltek, Sergey E.

    2015-11-01

    Microorganism identification by MALDI TOF mass-spectrometry is based on the comparison of the mass spectrum of the studied organism with those of reference strains. It is a rapid and reliable method. However, commercial databases and programs are mostly designed for identification of clinically important strains and can be used only for particular mass spectrometer models. The need for open platforms and reference databases is obvious. In this study we describe a geometric approach for microorganism identification by mass spectra and demonstrate its capabilities by analyzing 24 strains belonging to the Bacillus pumilus group. This method is based on representing mass spectra as points on a multidimensional space, which allows us to use geometric distances to compare the spectra. Delimitation of microorganisms performed by geometric approach correlates well with the results of molecular phylogenetic analysis and clustering using Biotyper 3.1. All three methods used allowed us to reliably divide the strains into two groups corresponding to closely related species, Bacillus pumilus and Bacillus altitudinis. The method developed by us will be implemented in a Web interface designed for using open reference databases for microorganism identification. The data is available at http://www.bionet.nsc.ru/mbl/database/database.html.

  6. Morphometric growth relationships of the immature human mandible and tongue.

    Science.gov (United States)

    Hutchinson, Erin F; Kieser, Jules A; Kramer, Beverley

    2014-06-01

    The masticatory apparatus is a highly adaptive musculoskeletal complex comprising several relatively independent structural components, which assist in functions including feeding and breathing. We hypothesized that the tongue is elemental in the maintenance of normal ontogeny of the mandible and in its post-natal growth and development, and tested this using a morphometric approach. We assessed tongue and mandibular measurements in 174 (97 male) human cadavers. Landmark lingual and mandibular data were gathered individuals aged between 20 gestational weeks and 3 yr postnatal. In this analysis, geometric morphometrics assisted in visualizing the morphometrical growth changes in the mandible and tongue. A linear correlation in conjunction with principal component analysis further visualized the growth relationship between these structures. We found that the growth of the tongue and mandible were intrinsically linked in size and shape between 20 gestational weeks and 24 months postnatal. However, the mandible continued to change in shape and size into the 3rd yr of life, whereas the tongue only increased in size over this same period of time. These findings provide valuable insights into the allometric growth relationship between these structures, potentially assisting the clinician in predicting the behaviour of these structures in the assessment of malocclusions.

  7. A discrete geometric approach to solving time independent Schrödinger equation

    Science.gov (United States)

    Specogna, Ruben; Trevisan, Francesco

    2011-02-01

    The time independent Schrödinger equation stems from quantum theory axioms as a partial differential equation. This work aims at providing a novel discrete geometric formulation of this equation in terms of integral variables associated with precise geometric elements of a pair of three-dimensional interlocked grids, one of them based on tetrahedra. We will deduce, in a purely geometric way, a computationally efficient discrete counterpart of the time independent Schrödinger equation in terms of a standard symmetric eigenvalue problem. Moreover boundary and interface conditions together with non homogeneity and anisotropy of the media involved are accounted for in a straightforward manner. This approach yields to a sensible computational advantage with respect to the finite element method, where a generalized eigenvalue problem has to be solved instead. Such a modeling tool can be used for analyzing a number of quantum phenomena in modern nano-structured devices, where the accounting of the real 3D geometry is a crucial issue.

  8. Energy Conservation Law in Industrial Architecture: An Approach through Geometric Algebra

    Directory of Open Access Journals (Sweden)

    Juan C. Bravo

    2016-09-01

    Full Text Available Since 1892, the electrical engineering scientific community has been seeking a power theory for interpreting the power flow within electric networks under non-sinusoidal conditions. Although many power theories have been proposed regarding non-sinusoidal operation, an adequate solution is yet to be found. Using the framework based on complex algebra in non-sinusoidal circuit analysis (frequency domain, the verification of the energy conservation law is only possible in sinusoidal situations. In this case, reactive energy turns out to be proportional to the energy difference between the average electric and magnetic energies stored in the loads and its cancellation is mathematically trivial. However, in industrial architecture, apparent power definition of electric loads (non-sinusoidal conditions is inconsistent with the energy conservation law. Up until now, in the classical complex algebra approach, this goal is only valid in the case of purely resistive loads. Thus, in this paper, a new circuit analysis approach using geometric algebra is used to develop the most general proof of energy conservation in industrial building loads. In terms of geometric objects, this powerful tool calculates the voltage, current, and apparent power in electrical systems in non-sinusoidal, linear/nonlinear situations. In contrast to the traditional method developed by Steinmetz, the suggested powerful tool extends the concept of phasor to multivector-phasors and is performed in a new Generalized Complex Geometric Algebra structure (CGn, where Gn is the Clifford algebra in n-dimensional real space and C is the complex vector space. To conclude, a numerical example illustrates the clear advantages of the approach suggested in this paper.

  9. A Geometrical Approach to Hojman Theorem of a Rotational Relativistic Birkhoffian System

    Institute of Scientific and Technical Information of China (English)

    ZHANGYi

    2004-01-01

    A geometrical approach to the Hojman theorem of a rotational relativistic Birkhoffian system is presented.The differential equations of motion of the system are established. According to the invariance of differential equations under infinitesimal transformation, the determining equations of Lie symmetry are constructed. A new conservation law of the system, called Hojman theorem, is obtained, which is the generalization of previous results given sequentially by Hojman, Zhang, and Luo et al. In terms of the theory of modern differential geometry a proof of the theorem is given.

  10. From circular paths to elliptic orbits A geometric approach to Kepler's motion

    CERN Document Server

    González-Villanueva, A; Martínez y Romero, R P; Núñez-Yépez, H N; Salas-Brito, A L

    1998-01-01

    The hodograph, i.e. the path traced by a body in velocity space, was introduced by Hamilton in 1846 as an alternative for studying certain dynamical problems. The hodograph of the Kepler problem was then investigated and shown to be a circle, it was next used to investigate some other properties of the motion. We here propose a new method for tracing the hodograph and the corresponding configuration space orbit in Kepler's problem starting from the initial conditions given and trying to use no more than the methods of synthetic geometry in a sort of Newtonian approach. All of our geometric constructions require straight edge and compass only.

  11. A geometric approach to regulator and tracker design for an aerospace plane

    Science.gov (United States)

    Van Buren, Mark A.; Mease, Kenneth D.

    1991-01-01

    The paper presents a nonlinear design approach drawing from singular perturbations, feedback linearization, and variable structure control, that leads to regulators with automatic gain scheduling which exhibit similar dynamic behavior over the entire flight envelope of the aerospace plane. Additionally, design approach provides for a systematic way to counter disturbance effects as well as modeling uncertainties. The unifying feature of the three nonlinear feedback control methodologies is that they all have a geometric interpretation. First, the translational dynamics are decomposed into reduced-order slow and fast dynamics by way of a formal singular perturbation analysis. After feedback linearization the fast dynamics are robustly stabilized via a variable structure control approach. The slow dynamics are stabilized using conventional proportional-integral compensation based on the nominal slow dynamics. A number of sample command and disturbance responses at opposite ends of the flight envelope are presented for a nonlinear aerospace plane model.

  12. Ventricular dyssynchrony assessed by gated myocardial perfusion SPECT using a geometrical approach: a feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Veen, Berlinda J. van der; Younis, Imad Al [Leiden University Medical Centre, Department of Nuclear Medicine, Leiden (Netherlands); Ajmone-Marsan, Nina; Bax, Jeroen J. [Leiden University Medical Centre, Department of Cardiology, Leiden (Netherlands); Westenberg, Jos J.M.; Roos, Albert de [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands); Stokkel, Marcel P.M. [Antoni van Leeuwenhoek Hospital, Department of Nuclear Medicine, Netherlands Cancer Institute, Amsterdam (Netherlands)

    2012-03-15

    Left ventricular dyssynchrony may predict response to cardiac resynchronization therapy and may well predict adverse cardiac events. Recently, a geometrical approach for dyssynchrony analysis of myocardial perfusion scintigraphy (MPS) was introduced. In this study the feasibility of this geometrical method to detect dyssynchrony was assessed in a population with a normal MPS and in patients with documented ventricular dyssynchrony. For the normal population 80 patients (40 men and 40 women) with normal perfusion (summed stress score {<=}2 and summed rest score {<=}2) and function (left ventricular ejection fraction 55-80%) on MPS were selected; 24 heart failure patients with proven dyssynchrony on MRI were selected for comparison. All patients underwent a 2-day stress/rest MPS protocol. Perfusion, function and dyssynchrony parameters were obtained by the Corridor4DM software package (Version 6.1). For the normal population time to peak motion was 42.8 {+-} 5.1% RR cycle, SD of time to peak motion was 3.5 {+-} 1.4% RR cycle and bandwidth was 18.2 {+-} 6.0% RR cycle. No significant gender-related differences or differences between rest and post-stress acquisition were found for the dyssynchrony parameters. Discrepancies between the normal and abnormal populations were most profound for the mean wall motion (p value <0.001), SD of time to peak motion (p value <0.001) and bandwidth (p value <0.001). It is feasible to quantify ventricular dyssynchrony in MPS using the geometrical approach as implemented by Corridor4DM. (orig.)

  13. Computed tomography morphometric analysis of the central clival depression and petroclival angle for application of the presigmoid approach in the pediatric population

    Directory of Open Access Journals (Sweden)

    Sohum K Desai

    2016-01-01

    Full Text Available Aims: Lateral transtemporal approaches are useful for addressing lesions located ventral to the brainstem, especially when the pathologic diagnosis of the tumor dictates that a gross or near total resection improves outcomes. One approach, the presigmoid approach receives little attention in the pediatric population thus far. We sought to characterize morphometric changes, particularly the clival depth and the petroclival Cobb angle, that occur in the temporal bones of children and draw implications about doing a presigmoid approach in children. Settings and Design: This study was a retrospective study performed at John Sealy Hospital, a level-one trauma center that takes care of pediatric injuries as well. Subjects and Methods: We performed a morphometric analysis of noncontrast computed tomography head studies in 96 boys and 67 girls. Central clival depth and petroclival angle were obtained in the axial plane at the level of the internal auditory meatus using the method described by Abdel Aziz et al. Statistical Analysis Used: Descriptive statistics and Student′s t-test to compare groups were calculated using Microsoft Excel. Results: We found no gender difference in mean central clival depth or petroclival angle (P = 0.98 and P = 0.61, respectively. However, when we broke our cohort by age into those younger than 9 years of age and those 10 years or older, we found the petroclival angle decreased by 6.2° which was statistically significant (P < 0.000000006. Conclusions: These findings suggest that a presigmoid retrolabyrinthine approach is useful for children 9 years of age and younger as the petroclival angle appears to decrease resulting in a shallower clival depression in these patients.

  14. Morfometría geométrica en cinco especies de Buthidae y Scorpionidae (Arachnida: Scorpiones de Venezuela Geometric morphometrics in five species of Buthidae and Scorpionidae (Arachnida: Scorpiones from Venezuela

    Directory of Open Access Journals (Sweden)

    Walter Y. Bechara

    2012-06-01

    Full Text Available En Venezuela, la escorpiofauna consta de 17 géneros y 202 especies. En algunos grupos la taxonomía no ha sido aclarada; por lo tanto, son necesarias investigaciones adicionales que contribuyan a mejorar el conocimiento sobre la identidad taxonómica y relaciones entre sus componentes. La morfometría geométrica es una herramienta que ha sido utilizada como apoyo a la sistemática en distintos organismos. El objetivo del presente trabajo fue analizar la conformación y tamaño isométrico en 5 especies de escorpiones. Se fotografiaron 266 individuos de 4 especies de Buthidae: Centruroides testaceus, Rhopalurus laticauda, Tityus clathratus y T. discrepans, y una de Scorpionidae: Tarsoporosus yustizi. Se registraron configuraciones de coordenadas (x,y en 5 estructuras a partir de puntos anatómicos de referencia (PAR y PAR deslizantes. Los resultados mostraron separación completa de las especies de Buthidae por medio de tricobotrias dorsales en la patela del pedipalpo, y una consistente separación en el nivel familiar en las estructuras restantes. Las placas delgadas permitieron la visualización de compresión horizontal del esternón en las especies de Buthidae y compresión vertical en la de Scorpionidae. Se determinó la similitud de coxas, quela y caparazón entre R. laticauda y C. testaceus. La disposición de tricobotrias y la conformación del esternón permitió la diferenciación entre T. discrepans y T. clathratus.The Venezuelan scorpionfauna comprises 17 genera and 202 species. In some taxa the taxonomy is unclear, and additional studies that contribute to the knowledge about taxonomic identity and relationships are necessary. Geometric morphometrics is a tool that has been used as support to the systematics in different organisms. The goal was to analize the isometric size and conformation in five scorpions species. We photographed 266 individuals of four speceis of Buthidae: Centruroides testaceus, Rhopalurus laticauda, Tityus

  15. MartiTracks: a geometrical approach for identifying geographical patterns of distribution.

    Directory of Open Access Journals (Sweden)

    Susy Echeverría-Londoño

    Full Text Available Panbiogeography represents an evolutionary approach to biogeography, using rational cost-efficient methods to reduce initial complexity to locality data, and depict general distribution patterns. However, few quantitative, and automated panbiogeographic methods exist. In this study, we propose a new algorithm, within a quantitative, geometrical framework, to perform panbiogeographical analyses as an alternative to more traditional methods. The algorithm first calculates a minimum spanning tree, an individual track for each species in a panbiogeographic context. Then the spatial congruence among segments of the minimum spanning trees is calculated using five congruence parameters, producing a general distribution pattern. In addition, the algorithm removes the ambiguity, and subjectivity often present in a manual panbiogeographic analysis. Results from two empirical examples using 61 species of the genus Bomarea (2340 records, and 1031 genera of both plants and animals (100118 records distributed across the Northern Andes, demonstrated that a geometrical approach to panbiogeography is a feasible quantitative method to determine general distribution patterns for taxa, reducing complexity, and the time needed for managing large data sets.

  16. A synoptic approach to the seismic sensing of heterogeneous fractures: from geometric reconstruction to interfacial characterization

    CERN Document Server

    Pourahmadian, Fatemeh; Haddar, Houssem

    2016-01-01

    A non-iterative waveform sensing approach is proposed toward (i) geometric reconstruction of penetrable fractures, and (ii) quantitative identification of their heterogeneous contact condition by seismic i.e. elastic waves. To this end, the fracture support $\\Gamma$ (which may be non-planar and unconnected) is first recovered without prior knowledge of the interfacial condition by way of the recently established approaches to non-iterative waveform tomography of heterogeneous fractures, e.g. the methods of generalized linear sampling and topological sensitivity. Given suitable approximation $\\breve\\Gamma$ of the fracture geometry, the jump in the displacement field across $\\breve\\Gamma$ i.e. the fracture opening displacement (FOD) profile is computed from remote sensory data via a regularized inversion of the boundary integral representation mapping the FOD to remote observations of the scattered field. Thus obtained FOD is then used as input for solving the traction boundary integral equation on $\\breve\\Gamm...

  17. Geometric approach to optimal nonequilibrium control: Minimizing dissipation in nanomagnetic spin systems

    Science.gov (United States)

    Rotskoff, Grant M.; Crooks, Gavin E.; Vanden-Eijnden, Eric

    2017-01-01

    Optimal control of nanomagnets has become an urgent problem for the field of spintronics as technological tools approach thermodynamically determined limits of efficiency. In complex, fluctuating systems, such as nanomagnetic bits, finding optimal protocols is challenging, requiring detailed information about the dynamical fluctuations of the controlled system. We provide a physically transparent derivation of a metric tensor for which the length of a protocol is proportional to its dissipation. This perspective simplifies nonequilibrium optimization problems by recasting them in a geometric language. We then describe a numerical method, an instance of geometric minimum action methods, that enables computation of geodesics even when the number of control parameters is large. We apply these methods to two models of nanomagnetic bits: a Landau-Lifshitz-Gilbert description of a single magnetic spin controlled by two orthogonal magnetic fields, and a two-dimensional Ising model in which the field is spatially controlled. These calculations reveal nontrivial protocols for bit erasure and reversal, providing important, experimentally testable predictions for ultra-low-power computing.

  18. A reinforcement learning approach to model interactions between landmarks and geometric cues during spatial learning.

    Science.gov (United States)

    Sheynikhovich, Denis; Arleo, Angelo

    2010-12-13

    In contrast to predictions derived from the associative learning theory, a number of behavioral studies suggested the absence of competition between geometric cues and landmarks in some experimental paradigms. In parallel to these studies, neurobiological experiments suggested the existence of separate independent memory systems which may not always interact according to classic associative principles. In this paper we attempt to combine these two lines of research by proposing a model of spatial learning that is based on the theory of multiple memory systems. In our model, a place-based locale strategy uses activities of modeled hippocampal place cells to drive navigation to a hidden goal, while a stimulus-response taxon strategy, presumably mediated by the dorso-lateral striatum, learns landmark-approaching behavior. A strategy selection network, proposed to reside in the prefrontal cortex, implements a simple reinforcement learning rule to switch behavioral strategies. The model is used to reproduce the results of a behavioral experiment in which an interaction between a landmark and geometric cues was studied. We show that this model, built on the basis of neurobiological data, can explain the lack of competition between the landmark and geometry, potentiation of geometry learning by the landmark, and blocking. Namely, we propose that the geometry potentiation is a consequence of cooperation between memory systems during learning, while blocking is due to competition between the memory systems during action selection.

  19. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir

    2012-06-01

    This paper deals with the problem of detection and isolation of stator short-circuit failure in a single asynchronous machine using a geometric approach. After recalling the basis of the geometric approach for fault detection and isolation in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter structure, both aiming at generating residuals which are sensitive to one fault and insensitive to the other faults. Some numerical tests will be presented to illustrate the efficiency of the method.

  20. A multi objective geometric programming approach for electronic product pricing problem

    Directory of Open Access Journals (Sweden)

    Mohsen Fathollah Bayati

    2011-07-01

    Full Text Available Nowadays electronic commerce plays an important role in many business activities, operations, and transaction processing. The recent advances on e-businesses have created tremendous opportunities to increase profitability. This paper presents a multi-objective marketing planning model which simultaneously determines efficient marketing expenditure, service cost and product's selling price in two competitive markets. To solve the proposed model, we discuss a multi-objective geometric programming (GP approach based on compromise programming method. Since our proposed model is a signomial GP and global optimality is not guaranteed for the problem, we transform the model to posynomial form. Finally, the solution procedure is illustrated via a numerical example and a sensitivity analysis is presented.

  1. Contraction of Information on Brain Wave Fluctuations by Information Geometrical Approach

    Science.gov (United States)

    Konno, Hidetoshi

    2005-08-01

    We will first propose a method of EEG signal identification with the use of the stochastic complex Ginzburg-Landau (CGL) equation having complex coefficients with the aid of the method of information geometrical approach to determine the system parameters. After the contracting information on the natures of fluctuations of amplitude and phase in the EEG signals on human scalp, we combine the information with other information such as complex measures like Higuchi's fractal dimension and multi-scale entropies. A new theory of unification of the information is also proposed. To exhibit the potentiality of our new method, we show the result of application of the theory and method to practical EEG data from elderly sound and demented people.

  2. Error performance analysis in K-tier uplink cellular networks using a stochastic geometric approach

    KAUST Repository

    Afify, Laila H.

    2015-09-14

    In this work, we develop an analytical paradigm to analyze the average symbol error probability (ASEP) performance of uplink traffic in a multi-tier cellular network. The analysis is based on the recently developed Equivalent-in-Distribution approach that utilizes stochastic geometric tools to account for the network geometry in the performance characterization. Different from the other stochastic geometry models adopted in the literature, the developed analysis accounts for important communication system parameters and goes beyond signal-to-interference-plus-noise ratio characterization. That is, the presented model accounts for the modulation scheme, constellation type, and signal recovery techniques to model the ASEP. To this end, we derive single integral expressions for the ASEP for different modulation schemes due to aggregate network interference. Finally, all theoretical findings of the paper are verified via Monte Carlo simulations.

  3. [A general approach to the structural shape optimization using genetic algorithms and geometric design elements].

    Science.gov (United States)

    Annicchiarico, W

    2001-01-01

    Structural optimization is an engineering field which deal with the improvement of existing solutions or even more find new solutions that are better than the previous ones under some selected criterion. Shape optimization is a research area in this field and it is involved in developing new methodologies to find better structural design based on the shape as resistant element, as for example solutions with the less stress concentration zones and made with the minimum amount of material. The goal of this doctoral dissertation is to present and discuss a general structural shape optimization methodology able to optimize several structural systems or mechanical devices. The approach presented herein is based on global search optimization tools such as Genetic Algorithms and geometric design elements by means of beta-splines curves and surfaces representation. Finally the great versatility of the developed tool is presented and discussed with an application example.

  4. Possibilities of 3-D modelling and quantitative morphometric analysis of decimeter-sized Echinoids using photogrammetric approach

    Science.gov (United States)

    Polonkai, Bálint; Görög, Ágnes; Raveloson, Andrea; Bodor, Emese; Székely, Balázs

    2017-04-01

    Echinoids (sea urchins) are useful fossils in palaeoenvironmental reconstruction for e.g. palaeobiogeography, palaeoclimatology or sedimentatological researches. In the Hungarian Badenian stage (Langhian, Middle Miocene) the species Parascutella gibbercula (DE SERRES 1829) is a common taxon and indicate shallow marine environment. The specimens of this extinct species show high morphological variability within relatively small geographical areas, even within one given strata. These differences can have a relevant palaeontological and/or palaeoenvironmental information. It is necessary for the interpretation of the value of the morphological parameters to quantify them in properties. Among the possible quantification methods 3D photogrammetric reconstruction is found to be suitable; recent years have seen its increasing palaeontological application both on invertebrates and vertebrates. In order to generate proper 3D models of the specimens with the required details a great number of digital images have to be shot. In case of proper data acquisition and precise model generation it is possible to outperform the traditional 2D morphometric studies of the echinoids that are often inaccurate when the spatial characters as well as ambulacral system and the conical shaped apex (top of the test) are measured. An average P . gibbercula specimen is about 10 cm diameter. Therefore, desktop image acquisition is possible if appropriate lighting conditions are provided. For better results we have designed an elaborate target background pattern that enhances the chances to find homologous points in the imagery. Agisoft Photoscan software has been used for the model generation. The generated models typically show high-resolution details and reproduce original colours. However, various problems may occur: improper focusing and/or poor lighting conditions may cause hardly patchable aboral and oral side, and/or shallow surface undulations cannot be modelled appropriately. Another

  5. Taxonomy of prickly juniper (Juniperus oxycedrus group): A phytochemical-morphometric combined approach at the contact zone of two cryptospecies.

    Science.gov (United States)

    Roma-Marzio, Francesco; Najar, Basma; Alessandri, John; Pistelli, Luisa; Peruzzi, Lorenzo

    2017-09-01

    Based on different essential oil composition paralleling different genotypes, Juniperus deltoides was recently segregated from Juniperus oxycedrus. Despite a clear phytochemical and molecular differentiation, J. deltoides resulted not clearly morphologically discernible from J. oxycedrus, so that it was defined as a cryptospecies. Italy represents the contact zone of their distribution, but the ranges of the two species are not sufficiently known, due to unsatisfactory morphological characterisation. To further complicate the picture, a third closely related species (ecotype), J. macrocarpa, occurs all across the Mediterranean coasts. After a preliminary phytochemical analysis to ascertain the (chemo-)identities of the studied populations, we performed a morphometric investigation to test the degree of morphological distinctiveness among the taxa. According to our analysis, some character (e.g. leaf mucro length, leaf width, seed-cone size and seed size) resulted useful to discriminate these cryptic taxa. Finally, based on these characters, an extensive revision of herbarium specimens allowed us to redefine the distribution pattern of the investigated species in the Central Mediterranean area. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Linear stratified approach using full geometric constraints for 3D scene reconstruction and camera calibration.

    Science.gov (United States)

    Kim, Jae-Hean; Koo, Bon-Ki

    2013-02-25

    This paper presents a new linear framework to obtain 3D scene reconstruction and camera calibration simultaneously from uncalibrated images using scene geometry. Our strategy uses the constraints of parallelism, coplanarity, colinearity, and orthogonality. These constraints can be obtained in general man-made scenes frequently. This approach can give more stable results with fewer images and allow us to gain the results with only linear operations. In this paper, it is shown that all the geometric constraints used in the previous works performed independently up to now can be implemented easily in the proposed linear method. The study on the situations that cannot be dealt with by the previous approaches is also presented and it is shown that the proposed method being able to handle the cases is more flexible in use. The proposed method uses a stratified approach, in which affine reconstruction is performed first and then metric reconstruction. In this procedure, the additional constraints newly extracted in this paper have an important role for affine reconstruction in practical situations.

  7. Morphological correlates of sprint swimming speed in five species of spadefoot toad tadpoles: comparison of morphometric methods.

    Science.gov (United States)

    Arendt, Jeff

    2010-09-01

    The relationship between vertebrate morphology and swimming performance has long interested biologists. Recent work on predator-induced morphological plasticity of anuran tadpoles has increased this interest. Here, I use data on five species of spadefoot toad tadpoles (Scaphiopodidae) to compare linear and geometric morphometrics. Linear measures explain only 7-26% of the variation in swimming speed, depending on species, whereas geometric morphometrics could explain 24-46% of the same variation. I also compare two methods for examining how similar the morphology-swimming speed relationship is among species. A canonical variate derived from a MANCOVA approach successfully detected species differences in these relationships, whether using linear or geometric methods, but a canonical correlation approach failed in both cases. Overall, tadpoles with smaller bodies, larger tails, and larger tail muscles are faster swimmers but the details of how these shape changes are achieved differed among species. For example, in some species a smaller body was achieved primarily by reducing abdomen size, whereas in others both the head and abdomen are smaller.Faster swimmers also had deeper tails, especially in the posterior half of the tail. This pattern would have been missed in standard linear morphometrics which usually only measures maximum tail depth.

  8. Morphometrics and the role of the phenotype in studies of the evolution of developmental mechanisms.

    Science.gov (United States)

    Klingenberg, Christian Peter

    2002-04-03

    Developmental mechanisms are usually assumed to evolve by natural selection of the morphological traits they produce. Therefore, information on phenotypic traits is an important component of comparative studies of development. Morphometrics permits the rigorous quantitative analysis of variation in organismal size and shape, and is increasingly being used in developmental contexts. The new methods of morphometrics combine a geometric concept of shape with the procedures of multivariate statistics, and constitute a powerful and flexible set of tools for analyzing morphological variation. This paper briefly reviews these methods and provides examples of their application in studies of genetic variation and developmental modularity. The results of morphometric analyses can be readily interpreted in relation to the geometry and anatomical structure of the parts under study. Genetic studies of shape in the mouse mandible found two recurrent patterns in environmental and genetic variation from different origins, suggesting that the development system 'channels' the phenotypic expression of variation in similar ways. Moreover, by analyzing the correlations of left-right asymmetries of morphometric traits, it is possible to delimit the spatial extent of developmental modules. These methods complement the experimental approaches of developmental biology and genetics, and can be expected to be especially fruitful in combination with them.

  9. A geometrical approach for automatic shape restoration of the left ventricle.

    Directory of Open Access Journals (Sweden)

    May-Ling Tan

    Full Text Available This paper describes an automatic algorithm that uses a geometry-driven optimization approach to restore the shape of three-dimensional (3D left ventricular (LV models created from magnetic resonance imaging (MRI data. The basic premise is to restore the LV shape such that the LV epicardial surface is smooth after the restoration and that the general shape characteristic of the LV is not altered. The Maximum Principle Curvature (k1 and the Minimum Principle Curvature (k2 of the LV epicardial surface are used to construct a shape-based optimization objective function to restore the shape of a motion-affected LV via a dual-resolution semi-rigid deformation process and a free-form geometric deformation process. A limited memory quasi-Newton algorithm, L-BFGS-B, is then used to solve the optimization problem. The goal of the optimization is to achieve a smooth epicardial shape by iterative in-plane and through-plane translation of vertices in the LV model. We tested our algorithm on 30 sets of LV models with simulated motion artifact generated from a very smooth patient sample, and 20 in vivo patient-specific models which contain significant motion artifacts. In the 30 simulated samples, the Hausdorff distances with respect to the Ground Truth are significantly reduced after restoration, signifying that the algorithm can restore geometrical accuracy of motion-affected LV models. In the 20 in vivo patient-specific models, the results show that our method is able to restore the shape of LV models without altering the general shape of the model. The magnitudes of in-plane translations are also consistent with existing registration techniques and experimental findings.

  10. Biometrics, biomathematics and the morphometric synthesis.

    Science.gov (United States)

    Bookstein, F L

    1996-03-01

    At the core of contemporary morphometrics--the quantitative study of biological shape variation--is a synthesis of two originally divergent methodological styles. One contributory tradition is the multivariate analysis of covariance matrices originally developed as biometrics and now dominant across a broad expanse of applied statistics. This approach, couched solely in the linear geometry of covariance structures, ignores biomathematical aspects of the original measurements. The other tributary emphasizes the direct visualization of changes in biological form. However, making objective the biological meaning of the features seen in those diagrams was always problematical; also, the representation of variation, as distinct from pairwise difference, proved infeasible. To combine these two variants of biomathematical modeling into a valid praxis for quantitative studies of biological shape was a goal earnestly sought though most of this century. That goal was finally achieved in the 1980s when techniques from mathematical statistics, multivariate biometrics, non-Euclidean geometry and computer graphics were combined in a coherent new system of tools for the complete regionalized quantitative analysis of landmark points together with the biomedical images in which they are seen. In this morphometric synthesis, correspondence of landmarks (biologically labeled geometric points, like "bridge of the nose") across specimens is taken as a biomathematical primitive. The shapes of configurations of landmarks are defined as equivalence classes with respect to the Euclidean similarity group and then represented as single points in David Kendall's shape space, a Riemannian manifold with Procrustes distance as metric. All conventional multivariate strategies carry over to the study of shape variation and covariation when shapes are interpreted in the tangent space to the shape manifold at an average shape. For biomathematical interpretation of such analyses, one needs a basis

  11. Life-times of quantum resonances through the Geometrical Phase Propagator Approach

    Science.gov (United States)

    Pavlou, G. E.; Karanikas, A. I.; Diakonos, F. K.

    2016-12-01

    We employ the recently introduced Geometric Phase Propagator Approach (GPPA) (Diakonos et al., 2012) to develop an improved perturbative scheme for the calculation of life times in driven quantum systems. This incorporates a resummation of the contributions of virtual processes starting and ending at the same state in the considered time interval. The proposed procedure allows for a strict determination of the conditions leading to finite life times in a general driven quantum system by isolating the resummed terms in the perturbative expansion contributing to their generation. To illustrate how the derived conditions apply in practice, we consider the effect of driving in a system with purely discrete energy spectrum, as well as in a system for which the eigenvalue spectrum contains a continuous part. We show that in the first case, when the driving contains a dense set of frequencies acting as a noise to the system, the corresponding bound states acquire a finite life time. When the energy spectrum contains also a continuum set of eigenvalues then the bound states, due to the driving, couple to the continuum and become quasi-bound resonances. The benchmark of this change is the appearance of a Fano-type peak in the associated transmission profile. In both cases the corresponding life-time can be efficiently estimated within the reformulated GPPA approach.

  12. A differential-geometric approach to generalized linear models with grouped predictors

    NARCIS (Netherlands)

    Augugliaro, Luigi; Mineo, Angelo M.; Wit, Ernst C.

    2016-01-01

    We propose an extension of the differential-geometric least angle regression method to perform sparse group inference in a generalized linear model. An efficient algorithm is proposed to compute the solution curve. The proposed group differential-geometric least angle regression method has important

  13. SIMULATION EXPERIMENT ON LANDING SITE SELECTION USING A SIMPLE GEOMETRIC APPROACH

    Directory of Open Access Journals (Sweden)

    W. Zhao

    2017-07-01

    Full Text Available Safe landing is an important part of the planetary exploration mission. Even fine scale terrain hazards (such as rocks, small craters, steep slopes, which would not be accurately detected from orbital reconnaissance could also pose a serious risk on planetary lander or rover and scientific instruments on-board it. In this paper, a simple geometric approach on planetary landing hazard detection and safe landing site selection is proposed. In order to achieve full implementation of this algorithm, two easy-to-compute metrics are presented for extracting the terrain slope and roughness information. Unlike conventional methods which must do the robust plane fitting and elevation interpolation for DEM generation, in this work, hazards is identified through the processing directly on LiDAR point cloud. For safe landing site selection, a Generalized Voronoi Diagram is constructed. Based on the idea of maximum empty circle, the safest landing site can be determined. In this algorithm, hazards are treated as general polygons, without special simplification (e.g. regarding hazards as discrete circles or ellipses. So using the aforementioned method to process hazards is more conforming to the real planetary exploration scenario. For validating the approach mentioned above, a simulated planetary terrain model was constructed using volcanic ash with rocks in indoor environment. A commercial laser scanner mounted on a rail was used to scan the terrain surface at different hanging positions. The results demonstrate that fairly hazard detection capability and reasonable site selection was obtained compared with conventional method, yet less computational time and less memory usage was consumed. Hence, it is a feasible candidate approach for future precision landing selection on planetary surface.

  14. Simulation Experiment on Landing Site Selection Using a Simple Geometric Approach

    Science.gov (United States)

    Zhao, W.; Tong, X.; Xie, H.; Jin, Y.; Liu, S.; Wu, D.; Liu, X.; Guo, L.; Zhou, Q.

    2017-07-01

    Safe landing is an important part of the planetary exploration mission. Even fine scale terrain hazards (such as rocks, small craters, steep slopes, which would not be accurately detected from orbital reconnaissance) could also pose a serious risk on planetary lander or rover and scientific instruments on-board it. In this paper, a simple geometric approach on planetary landing hazard detection and safe landing site selection is proposed. In order to achieve full implementation of this algorithm, two easy-to-compute metrics are presented for extracting the terrain slope and roughness information. Unlike conventional methods which must do the robust plane fitting and elevation interpolation for DEM generation, in this work, hazards is identified through the processing directly on LiDAR point cloud. For safe landing site selection, a Generalized Voronoi Diagram is constructed. Based on the idea of maximum empty circle, the safest landing site can be determined. In this algorithm, hazards are treated as general polygons, without special simplification (e.g. regarding hazards as discrete circles or ellipses). So using the aforementioned method to process hazards is more conforming to the real planetary exploration scenario. For validating the approach mentioned above, a simulated planetary terrain model was constructed using volcanic ash with rocks in indoor environment. A commercial laser scanner mounted on a rail was used to scan the terrain surface at different hanging positions. The results demonstrate that fairly hazard detection capability and reasonable site selection was obtained compared with conventional method, yet less computational time and less memory usage was consumed. Hence, it is a feasible candidate approach for future precision landing selection on planetary surface.

  15. Geometric-Phase approach to macroscopic polarization in lattice fermion models

    Science.gov (United States)

    Ortiz, Gerardo; Martin, Richard M.; Ordejón, Pablo

    1996-03-01

    The Geometric-Phase approach is a convenient way to calculate changes in the macroscopic polarization of an insulating system, based on the concept that the integrated current is connected to the phase of the wavefunction of interacting electrons. The method has provided a powerful mathematical scheme to study dielectric phenomena in correlated systems. We have applied these ideas to a variety of strongly correlated lattice fermion models in one and two dimensions; in particular, the 3-band Hubbard model in Cu-O planes in the parent compounds of High-Temperature superconductors. We analyze the information contained in the phase when a quantum transition takes place as one parameter of the hamiltonian is adiabatically changed. Previous results assume a correlated insulator in zero macroscopic electric field. In presence of such a singular perturbation there is no stable ground state. We present a way to overcome this problem, the main idea of which consists in constraining the manifold where the electrons move, i.e., the configuration space of the N identical particles.

  16. Investigation of geometrical effects in the carbon allotropes manipulation based on AFM: multiscale approach

    Science.gov (United States)

    Korayem, M. H.; Hefzabad, R. N.; Homayooni, A.; Aslani, H.

    2017-01-01

    Carbon allotropes are used as nanocarriers for drug and cell delivery. To obtain an accurate result in the nanoscale, it is important to use a precise model. In this paper, a multiscale approach is presented to investigate the manipulation process of carbon allotropes based on atomic force microscopy (AFM). For this purpose, the AFM setup is separated into two parts with different sizes as macro field (MF) and nano field (NF). Using Kirchhoff's plate model, the cantilever (the main part of MF) is modeled. The molecular dynamics method is applied to model the NF part, and then the MF and NF are coupled with the multiscale algorithm. With this model, by considering the effect of size and shape, the manipulation of carbon allotropes is carried out. The manipulations of armchair CNTs and fullerenes are performed to study the diameter changing effects. The result shows that the manipulation and friction force increases by increasing the diameter. The result of the indentation depth for the armchair CNTs indicates that decreasing the diameter causes the indentation depth to reduce. Moreover, the manipulations of four kinds of carbon allotropes with the same number of atoms have been studied to investigate the geometrical effects. The shapes of these nanoparticles change from sphere to cylinder. The results illustrate that the manipulation and the friction force decrease as the nanoparticle shape varies from sphere to cylinder. The Von-Mises results demonstrate that by changing the nanoparticle shape from the spherical to the cylindrical form, the stress increases, although the manipulation force reduces.

  17. The Morphometrics of “Masculinity” in Human Faces

    Science.gov (United States)

    Mitteroecker, Philipp; Windhager, Sonja; Müller, Gerd B.; Schaefer, Katrin

    2015-01-01

    In studies of social inference and human mate preference, a wide but inconsistent array of tools for computing facial masculinity has been devised. Several of these approaches implicitly assumed that the individual expression of sexually dimorphic shape features, which we refer to as maleness, resembles facial shape features perceived as masculine. We outline a morphometric strategy for estimating separately the face shape patterns that underlie perceived masculinity and maleness, and for computing individual scores for these shape patterns. We further show how faces with different degrees of masculinity or maleness can be constructed in a geometric morphometric framework. In an application of these methods to a set of human facial photographs, we found that shape features typically perceived as masculine are wide faces with a wide inter-orbital distance, a wide nose, thin lips, and a large and massive lower face. The individual expressions of this combination of shape features—the masculinity shape scores—were the best predictor of rated masculinity among the compared methods (r = 0.5). The shape features perceived as masculine only partly resembled the average face shape difference between males and females (sexual dimorphism). Discriminant functions and Procrustes distances to the female mean shape were poor predictors of perceived masculinity. PMID:25671667

  18. APPROACHES TO GEOMETRIC DATA ANALYSIS ON BIG AREA ADDITIVELY MANUFACTURED (BAAM) PARTS

    Energy Technology Data Exchange (ETDEWEB)

    Dreifus, Gregory D [ORNL; Ally, Nadya R [ORNL; Post, Brian K [ORNL; Jin, Yuan [ORNL

    2016-01-01

    The promise of additive manufacturing is that a user can design and print complex geometries that are very difficult, if not impossible, to machine. The capabilities of 3D printing are restricted by a number of factors, including properties of the build material, time constraints, and geometric design restrictions. In this paper, a thorough accounting and study of the geometric restrictions that exist in the current iteration of additive manufacturing (AM) fused deposition modeling (FDM) technologies are discussed. Offline and online methodologies for collecting data sets for qualitative analysis of large scale AM, in particular Oak Ridge National Laboratory s (ORNL) big area additive manufacturing (BAAM) system, are summarized. In doing so, a survey of tools for designers and software developers is provided. In particular, strategies in which geometric data can be used as training sets for smarter AM technologies in the future are explained as well.

  19. Computational morphology a computational geometric approach to the analysis of form

    CERN Document Server

    Toussaint, GT

    1988-01-01

    Computational Geometry is a new discipline of computer science that deals with the design and analysis of algorithms for solving geometric problems. There are many areas of study in different disciplines which, while being of a geometric nature, have as their main component the extraction of a description of the shape or form of the input data. This notion is more imprecise and subjective than pure geometry. Such fields include cluster analysis in statistics, computer vision and pattern recognition, and the measurement of form and form-change in such areas as stereology and developmental biolo

  20. Geometrical approach in physical understanding of the Goos-Haenchen shift in one- and two-dimensional periodic structures.

    Science.gov (United States)

    Miri, Mehdi; Naqavi, Ali; Khavasi, Amin; Mehrany, Khashayar; Khorasani, Sina; Rashidian, Bizhan

    2008-12-15

    The Goos-Haenchen shift of a totally reflected beam at the planar interface of two dielectric media, as if the incident beam is reflected from beneath the interface between the incident and transmitted media, has been geometrically associated with the penetration of the incident photons in the less-dense forbidden transmission region. This geometrical approach is here generalized to analytically calculate the Goos-Haenchen shift in one- and two-dimensional periodic structures. Several numerical examples are presented, and the obtained results are successfully tested against the well-known Artman's formula. The proposed approach is shown to be a fast, simple, and efficient method that can provide good physical insight to the nature of the phenomenon.

  1. Reviewing the upper Pleistocene human footprints from the 'Sala dei Misteri' in the Grotta della Bàsura (Toirano, northern Italy) cave: An integrated morphometric and morpho-classificatory approach

    Science.gov (United States)

    Paolo Citton; Romano, Marco; Salvador, Isabella; Avanzini, Marco

    2017-08-01

    About thirty human footprints made approximately 12,000 years B.P. inside the 'Sala dei Misteri' Cave of Básura near Toirano, Liguria, northern Italy, were studied by standard ichnological analysis. Eleven of the best-preserved tracks were examined further using morpho-classificatory and morphometric approaches, in order to estimate the minimum number of trackmakers; biometric measurements were also used to tentatively determine their physical characteristics (e.g., height and age). Results indicate at least three different producers, two youths and the third of tender age. Analysis of the data demonstrate the power of 3D, of landmark-based morphometrics, and the utility of methods of forensic anthropology in the determination of human footprints. The study of the number of trackmakers using the principal component analysis (PCA) on 'multi-trampling' surfaces could represent a model in the ichnological study of cave sites.

  2. Geometric and Algebraic Approaches in the Concept of "Limit" and the Impact of the "Didactic Contract"

    Science.gov (United States)

    Elia, Iliada; Gagatsis, Athanasios; Panaoura, Areti; Zachariades, Theodosis; Zoulinaki, Fotini

    2009-01-01

    The present study explores students' abilities in conversions between geometric and algebraic representations, in problem-solving situations involving the concept of "limit" and the interrelation of these abilities with students' constructed understanding of this concept. An attempt is also made to examine the impact of the…

  3. Relational and geometric approaches to justifying the magnetic fields of astrophysical objects

    Science.gov (United States)

    Babenko, I. A.

    We propose justification of the Sutherland hypotheses about origin of the magnetic fields of the Earth, Sun and other astrophysical objects as a part of the relational theory of space-time and interactions ("binary geometrophysics") and multidimensional geometrical models of physical interactions (like the Kaluza-Klein theories).

  4. Geometric and Algebraic Approaches in the Concept of "Limit" and the Impact of the "Didactic Contract"

    Science.gov (United States)

    Elia, Iliada; Gagatsis, Athanasios; Panaoura, Areti; Zachariades, Theodosis; Zoulinaki, Fotini

    2009-01-01

    The present study explores students' abilities in conversions between geometric and algebraic representations, in problem-solving situations involving the concept of "limit" and the interrelation of these abilities with students' constructed understanding of this concept. An attempt is also made to examine the impact of the…

  5. Outline-based morphometrics, an overlooked method in arthropod studies?

    Science.gov (United States)

    Dujardin, Jean-Pierre; Kaba, D; Solano, P; Dupraz, M; McCoy, K D; Jaramillo-O, N

    2014-12-01

    Modern methods allow a geometric representation of forms, separating size and shape. In entomology, as well as in many other fields involving arthropod studies, shape variation has proved useful for species identification and population characterization. In medical entomology, it has been applied to very specific questions such as population structure, reinfestation of insecticide-treated areas and cryptic species recognition. For shape comparisons, great importance is given to the quality of landmarks in terms of comparability. Two conceptually and statistically separate approaches are: (i) landmark-based morphometrics, based on the relative position of a few anatomical "true" or "traditional" landmarks, and (ii) outline-based morphometrics, which captures the contour of forms through a sequence of close "pseudo-landmarks". Most of the studies on insects of medical, veterinary or economic importance make use of the landmark approach. The present survey makes a case for the outline method, here based on elliptic Fourier analysis. The collection of pseudo-landmarks may require the manual digitization of many points and, for this reason, might appear less attractive. It, however, has the ability to compare homologous organs or structures having no landmarks at all. This strength offers the possibility to study a wider range of anatomical structures and thus, a larger range of arthropods. We present a few examples highlighting its interest for separating close or cryptic species, or characterizing conspecific geographic populations, in a series of different vector organisms. In this simple application, i.e. the recognition of close or cryptic forms, the outline approach provided similar scores as those obtained by the landmark-based approach.

  6. Morfometría geométrica alar para la identificación de Chrysomya albiceps y C. megacephala (Diptera: Calliphoridae de Venezuela Geometric wing morphometrics for Chrysomya albiceps and C. megacephala identification (Diptera: Calliphoridae from Venezuela

    Directory of Open Access Journals (Sweden)

    Marianela Vásquez

    2012-09-01

    Full Text Available Calliphoridae es una de las familias con el mayor número de especies de importancia forense, donde sus fases inmaduras se alimentan y desarrollan sobre material en descomposición. En Venezuela, son pocos los estudios en este taxon, sin embargo se ha reportado la dominancia del género Chrysomya sobre los otros dípteros. El objetivo fue analizar la variación morfométrica en la arquitectura alar, como herramienta de apoyo a la identificación de dípteros de importancia forense. Se fotografiaron 168 alas de C. albiceps (n=111 y C. megacephala (n=57 y se registraron configuraciones de coordenadas (x, y, se alinearon mediante Análisis Generalizado de Procrustes. Se efectuaron Análisis de Componentes Principales y comparaciones pareadas entre distancia parcial de Procrustes. El análisis estadístico de varianza encontró diferencias en el tamaño isométrico del ala (Kruskal-Wallis. El ACP mostró la separación de ambas especies, y la prueba de configuraciones determinó diferencias significativas (F Goodall. Las principales diferencias entre ambas especies se encontraron en: ruptura de la subcosta, unión de R2+3 con el borde del ala, unión dm-cu, y unión de Cu con dm-cu, lo que confirma que la morfometría alar es una herramienta idónea en la discriminación de especies de Calliphoridae.Calliphoridae is one of the families with the greatest number of species with forensic importance, which immature stages feed and develop on decaying material. in Venezuela, there are few studies on this taxon reporting the dominance of Chrysomya over other carrion flies. The goal of this study was to analyze the variations on wing morphometrics, to support the identification of two forensic flies. For this we photographed a total of 168 wings from C. albiceps (n=111 and C. megacephala (n=57. Landmark coordinate (x, y configurations were registered and aligned by Generalized Procrustes Analysis. Principal Component Analysis and shape significance test

  7. Quantitative diagnosis of breast tumors by morphometric classification of microenvironmental myoepithelial cells using a machine learning approach

    Science.gov (United States)

    Yamamoto, Yoichiro; Saito, Akira; Tateishi, Ayako; Shimojo, Hisashi; Kanno, Hiroyuki; Tsuchiya, Shinichi; Ito, Ken-ichi; Cosatto, Eric; Graf, Hans Peter; Moraleda, Rodrigo R.; Eils, Roland; Grabe, Niels

    2017-01-01

    Machine learning systems have recently received increased attention for their broad applications in several fields. In this study, we show for the first time that histological types of breast tumors can be classified using subtle morphological differences of microenvironmental myoepithelial cell nuclei without any direct information about neoplastic tumor cells. We quantitatively measured 11661 nuclei on the four histological types: normal cases, usual ductal hyperplasia and low/high grade ductal carcinoma in situ (DCIS). Using a machine learning system, we succeeded in classifying the four histological types with 90.9% accuracy. Electron microscopy observations suggested that the activity of typical myoepithelial cells in DCIS was lowered. Through these observations as well as meta-analytic database analyses, we developed a paracrine cross-talk-based biological mechanism of DCIS progressing to invasive cancer. Our observations support novel approaches in clinical computational diagnostics as well as in therapy development against progression. PMID:28440283

  8. Voxel-based morphometric analysis in hypothyroidism using diffeomorphic anatomic registration via an exponentiated lie algebra algorithm approach.

    Science.gov (United States)

    Singh, S; Modi, S; Bagga, D; Kaur, P; Shankar, L R; Khushu, S

    2013-03-01

    The present study aimed to investigate whether brain morphological differences exist between adult hypothyroid subjects and age-matched controls using voxel-based morphometry (VBM) with diffeomorphic anatomic registration via an exponentiated lie algebra algorithm (DARTEL) approach. High-resolution structural magnetic resonance images were taken in ten healthy controls and ten hypothyroid subjects. The analysis was conducted using statistical parametric mapping. The VBM study revealed a reduction in grey matter volume in the left postcentral gyrus and cerebellum of hypothyroid subjects compared to controls. A significant reduction in white matter volume was also found in the cerebellum, right inferior and middle frontal gyrus, right precentral gyrus, right inferior occipital gyrus and right temporal gyrus of hypothyroid patients compared to healthy controls. Moreover, no meaningful cluster for greater grey or white matter volume was obtained in hypothyroid subjects compared to controls. Our study is the first VBM study of hypothyroidism in an adult population and suggests that, compared to controls, this disorder is associated with differences in brain morphology in areas corresponding to known functional deficits in attention, language, motor speed, visuospatial processing and memory in hypothyroidism. © 2012 British Society for Neuroendocrinology.

  9. A comparative hydro-morphometric approach for modelling rainfall variability impacts during hydrological extremes: Application to 2002 and 2003 catastrophic events in the Lower Rhône valley, France

    Science.gov (United States)

    Hénaff, Quentin; Arnaud-Fassetta, Gilles; Beltrando, Gérard; Gillet, Raphaël

    2014-05-01

    Recent catastrophic floods (2002 and 2003) in the Lower Rhône valley (LRV) demonstrated that hydrological extremes are caused by the addition of tributary flood peaks to the Rhône River overall volumetric flow rate. Flood regimes in the LRV, which is southward increasingly influenced by Mediterranean climate, are fundamentally affected by the hydro-meteorological variability of tributary catchments, especially in case of widespread flooding. This study aims to assess the relationship between the geographic variability of recent extreme rainfall events and tributaries contribution to hydrological extremes. We propose a comparative modelling approach in order to analyse the contribution rainfall/flow relationship using an automatic hydro-morphometric classification at the hydrosystem scale. The study was led between the right-bank confluences of the rivers Ardèche and Gard, separated from 60 km. This comparative approach should be able to highlight the correlation between the morphometry of the tributary catchments, extreme rainfall event variability and hydrological contribution of the tributaries, combining automated geoinformatic tools (GIS and statistical computing). Firstly, the spatial distribution of September 08-09, 2002 storm over the Cévennes (300-600 mm), November 13-18 and 23-25, 2002 rainfall events over the Provence Prealps (150-300 mm), and December 01-05, 2003 widespread rainfall event (200-300 mm), was integrated into a geographic database. Secondly, the contribution of tributary flood peaks was computed from flood hydrographs using a Gumbel distribution adjusted frequency flood-flow model. The last pre-processing step concerns the hydro-morphometric classification of the catchments combining 33 empirical morphometric indices of form (14), volume (11) and network (7). These indices were calculated and integrated into the geographic database. Tributary catchment hydro-morphometric classification was computed by hierarchical clustering on principal

  10. The geometric approach to sets of ordinary differential equations and Hamiltonian dynamics

    Science.gov (United States)

    Estabrook, F. B.; Wahlquist, H. D.

    1975-01-01

    The calculus of differential forms is used to discuss the local integration theory of a general set of autonomous first order ordinary differential equations. Geometrically, such a set is a vector field V in the space of dependent variables. Integration consists of seeking associated geometric structures invariant along V: scalar fields, forms, vectors, and integrals over subspaces. It is shown that to any field V can be associated a Hamiltonian structure of forms if, when dealing with an odd number of dependent variables, an arbitrary equation of constraint is also added. Families of integral invariants are an immediate consequence. Poisson brackets are isomorphic to Lie products of associated CT-generating vector fields. Hamilton's variational principle follows from the fact that the maximal regular integral manifolds of a closed set of forms must include the characteristics of the set.

  11. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid...... on a detailed nonlinear satellite model with embedded disturbance description. The results document the efficacy of the proposed diagnosis scheme....

  12. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    OpenAIRE

    Baldi, P.; Blanke, Mogens; P. Castaldi; Mimmo, N.; S. Simani

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid that aerodynamic disturbance torques have unwanted influence on the residuals exploited for fault detection and isolation. Radial basis function neural networks are used to obtain fault estimation filt...

  13. Comparison of two approaches for calculation of the geometric and inertial characteristics of the human body of the Bulgarian population.

    Science.gov (United States)

    Nikolova, Gergana; Toshev, Yuli

    2008-01-01

    On the basis of a representative anthropological investigation of 5290 individuals (2435 males and 2855 females) of the Bulgarian population at the age of 30-40 years (Yordanov et al. [1]) we proposed a 3D biomechanical model of human body of the average Bulgarian male and female and compared two different possible approaches to calculate analytically and to evaluate numerically the corresponding geometric and inertial characteristics of all the segments of the body. In the framework of the first approach, we calculated the positions of the centres of mass of the segments of human body as well as their inertial characteristics merely by using the initial original anthropometrical data, while in the second approach we adjusted the data by using the method based on regression equations. Wherever possible, we presented a comparison of our data with those available in the literature on other Caucasians and determined in which cases the use of which approach is more reliable.

  14. A geometric approach to study the contact mechanisms in the patellofemoral joint of normal versus patellofemoral pain syndrome subjects.

    Science.gov (United States)

    Islam, Kamrul; Duke, Kajsa; Mustafy, Tanvir; Adeeb, Samer M; Ronsky, Janet L; El-Rich, Marwan

    2015-01-01

    The biomechanics of the patellofemoral (PF) joint is complex in nature, and the aetiology of such manifestations of PF instability as patellofemoral pain syndrome (PFPS) is still unclear. At this point, the particular factors affecting PFPS have not yet been determined. This study has two objectives: (1) The first is to develop an alternative geometric method using a three-dimensional (3D) registration technique and linear mapping to investigate the PF joint contact stress using an indirect measure: the depth of virtual penetration (PD) of the patellar cartilage surface into the femoral cartilage surface. (2) The second is to develop 3D PF joint models using the finite element analysis (FEA) to quantify in vivo cartilage contact stress and to compare the peak contact stress location obtained from the FE models with the location of the maximum PD. Magnetic resonance images of healthy and PFPS subjects at knee flexion angles of 15°, 30° and 45° during isometric loading have been used to develop the geometric models. The results obtained from both approaches demonstrated that the subjects with PFPS show higher PD and contact stresses than the normal subjects. Maximum stress and PD increase with flexion angle, and occur on the lateral side in healthy and on the medial side in PFPS subjects. It has been concluded that the alternative geometric method is reliable in addition to being computationally efficient compared with FEA, and has the potential to assess the mechanics of PFPS with an accuracy similar to the FEA.

  15. Joint pricing and production management: a geometric programming approach with consideration of cubic production cost function

    Science.gov (United States)

    Sadjadi, Seyed Jafar; Hamidi Hesarsorkh, Aghil; Mohammadi, Mehdi; Bonyadi Naeini, Ali

    2014-08-01

    Coordination and harmony between different departments of a company can be an important factor in achieving competitive advantage if the company corrects alignment between strategies of different departments. This paper presents an integrated decision model based on recent advances of geometric programming technique. The demand of a product considers as a power function of factors such as product's price, marketing expenditures, and consumer service expenditures. Furthermore, production cost considers as a cubic power function of outputs. The model will be solved by recent advances in convex optimization tools. Finally, the solution procedure is illustrated by numerical example.

  16. Combined Geometric and Neural Network Approach to Generic Fault Diagnosis in Satellite Actuators and Sensors

    DEFF Research Database (Denmark)

    Baldi, P.; Blanke, Mogens; Castaldi, P.;

    2016-01-01

    This paper presents a novel scheme for diagnosis of faults affecting the sensors measuring the satellite attitude, body angular velocity and flywheel spin rates as well as defects related to the control torques provided by satellite reaction wheels. A nonlinear geometric design is used to avoid...... that aerodynamic disturbance torques have unwanted influence on the residuals exploited for fault detection and isolation. Radial basis function neural networks are used to obtain fault estimation filters that do not need a priori information about the fault internal models. Simulation results are based...... on a detailed nonlinear satellite model with embedded disturbance description. The results document the efficacy of the proposed diagnosis scheme....

  17. Stabilization of systems with one degree of underactuation with energy shaping, a geometric approach

    CERN Document Server

    Gharesifard, Bahman

    2010-01-01

    A geometric formulation for stabilization of systems with one degree of underactuation which fully solves the energy shaping problem for these system is given. The results show that any linearly controllable simple mechanical system with one degree of underactuation is stabilizable by energy shaping, possibly via a closed-loop metric which is not necessarily positive-definite. An example of a system with one degree of underactuation is provided for which the stabilization by energy shaping method is not achievable using a positive-definite closed-loop metric.

  18. Quantum phase transition in the Dzyaloshinskii-Moriya interaction with inhomogeneous magnetic field: Geometric approach

    Science.gov (United States)

    Najarbashi, G.; Seifi, B.

    2017-02-01

    In this paper, we generalize the results of Oh (Phys Lett A 373:644-647, 2009) to Dzyaloshinskii-Moriya model under non-uniform external magnetic field to investigate the relation between entanglement, geometric phase (or Berry phase) and quantum phase transition. We use quaternionic representation to relate the geometric phase to the quantum phase transition. For small values of DM parameter, the Berry phase is more appropriate than the concurrence measure, while for large values, the concurrence is a good indicator to show the phase transition. On the other hand, by increasing the DM interaction the phase transition occurs for large values of anisotropy parameter. In addition, for small values of magnetic field the concurrence measure is appropriate indicator for quantum phase transition, but for large values of magnetic field the Berry phase shows a sharp changes in the phase transition points. The results show that the Berry phase and concurrence form a complementary system from phase transition point of view.

  19. A probabilistic approach to randomness in geometric configuration of scalable origami structures

    Science.gov (United States)

    Liu, Ke; Paulino, Glaucio; Gardoni, Paolo

    2015-03-01

    Origami, an ancient paper folding art, has inspired many solutions to modern engineering challenges. The demand for actual engineering applications motivates further investigation in this field. Although rooted from the historic art form, many applications of origami are based on newly designed origami patterns to match the specific requirenments of an engineering problem. The application of origami to structural design problems ranges from micro-structure of materials to large scale deployable shells. For instance, some origami-inspired designs have unique properties such as negative Poisson ratio and flat foldability. However, origami structures are typically constrained by strict mathematical geometric relationships, which in reality, can be easily violated, due to, for example, random imperfections introduced during manufacturing, or non-uniform deformations under working conditions (e.g. due to non-uniform thermal effects). Therefore, the effects of uncertainties in origami-like structures need to be studied in further detail in order to provide a practical guide for scalable origami-inspired engineering designs. Through reliability and probabilistic analysis, we investigate the effect of randomness in origami structures on their mechanical properties. Dislocations of vertices of an origami structure have different impacts on different mechanical properties, and different origami designs could have different sensitivities to imperfections. Thus we aim to provide a preliminary understanding of the structural behavior of some common scalable origami structures subject to randomness in their geometric configurations in order to help transition the technology toward practical applications of origami engineering.

  20. Wall-Corner Classification Using Sonar: A New Approach Based on Geometric Features

    Directory of Open Access Journals (Sweden)

    Ginés Benet

    2010-11-01

    Full Text Available Ultrasonic signals coming from rotary sonar sensors in a robot gives us several features about the environment. This enables us to locate and classify the objects in the scenario of the robot. Each object and reflector produces a series of peaks in the amplitude of the signal. The radial and angular position of the sonar sensor gives information about location and their amplitudes offer information about the nature of the surface. Early works showed that the amplitude can be modeled and used to classify objects with very good results at short distances—80% average success in classifying both walls and corners at distances less than 1.5 m. In this paper, a new set of geometric features derived from the amplitude analysis of the echo is presented. These features constitute a set of characteristics that can be used to improve the results of classification at distances from 1.5 m to 4 m. Also, a comparative study on classification algorithms widely used in pattern recognition techniques has been carried out for sensor distances ranging between 0.5 to 4 m, and with incidence angles ranging between 20º to 70º. Experimental results show an enhancement on the success in classification rates when these geometric features are considered.

  1. Wall-corner classification using sonar: a new approach based on geometric features.

    Science.gov (United States)

    Martínez, Milagros; Benet, Ginés

    2010-01-01

    Ultrasonic signals coming from rotary sonar sensors in a robot gives us several features about the environment. This enables us to locate and classify the objects in the scenario of the robot. Each object and reflector produces a series of peaks in the amplitude of the signal. The radial and angular position of the sonar sensor gives information about location and their amplitudes offer information about the nature of the surface. Early works showed that the amplitude can be modeled and used to classify objects with very good results at short distances-80% average success in classifying both walls and corners at distances less than 1.5 m. In this paper, a new set of geometric features derived from the amplitude analysis of the echo is presented. These features constitute a set of characteristics that can be used to improve the results of classification at distances from 1.5 m to 4 m. Also, a comparative study on classification algorithms widely used in pattern recognition techniques has been carried out for sensor distances ranging between 0.5 to 4 m, and with incidence angles ranging between 20° to 70°. Experimental results show an enhancement on the success in classification rates when these geometric features are considered.

  2. On bifurcation delay: An alternative approach using Geometric Singular Perturbation Theory

    Science.gov (United States)

    Hsu, Ting-Hao

    2017-02-01

    To explain the phenomenon of bifurcation delay, which occurs in planar systems of the form x ˙ = ɛf (x , z , ɛ), z ˙ = g (x , z , ɛ) z, where f (x , 0 , 0) > 0 and g (x , 0 , 0) changes sign at least once on the x-axis, we use the Exchange Lemma in Geometric Singular Perturbation Theory to track the limiting behavior of the solutions. Using the trick of extending dimension to overcome the degeneracy at the turning point, we show that the limiting attracting and repulsion points are given by the well-known entry-exit function, and the minimum of z on the trajectory is of order exp ⁡ (- 1 / ɛ). Also we prove smoothness of the return map up to arbitrary finite order in ɛ.

  3. Computing the laser beam path in optical cavities: a geometric Newton's method based approach

    CERN Document Server

    Cuccato, Davide; Ortolan, Antonello; Beghi, Alessandro

    2015-01-01

    In the last decade, increasing attention has been drawn to high precision optical experiments, which push resolution and accuracy of the measured quantities beyond their current limits. This challenge requires to place optical elements (e.g. mirrors, lenses, etc.) and to steer light beams with sub-nanometer precision. Existing methods for beam direction computing in resonators, e.g. iterative ray tracing or generalized ray transfer matrices, are either computationally expensive or rely on overparametrized models of optical elements. By exploiting Fermat's principle, we develop a novel method to compute the steady-state beam configurations in resonant optical cavities formed by spherical mirrors, as a function of mirror positions and curvature radii. The proposed procedure is based on the geometric Newton method on matrix manifold, a tool with second order convergence rate that relies on a second order model of the cavity optical length. As we avoid coordinates to parametrize the beam position on mirror surfac...

  4. Riemannian geometric approach to human arm dynamics, movement optimization, and invariance.

    Science.gov (United States)

    Biess, Armin; Flash, Tamar; Liebermann, Dario G

    2011-03-01

    We present a generally covariant formulation of human arm dynamics and optimization principles in Riemannian configuration space. We extend the one-parameter family of mean-squared-derivative (MSD) cost functionals from Euclidean to Riemannian space, and we show that they are mathematically identical to the corresponding dynamic costs when formulated in a Riemannian space equipped with the kinetic energy metric. In particular, we derive the equivalence of the minimum-jerk and minimum-torque change models in this metric space. Solutions of the one-parameter family of MSD variational problems in Riemannian space are given by (reparameterized) geodesic paths, which correspond to movements with least muscular effort. Finally, movement invariants are derived from symmetries of the Riemannian manifold. We argue that the geometrical structure imposed on the arm's configuration space may provide insights into the emerging properties of the movements generated by the motor system.

  5. Maximum likelihood estimates with order restrictions on probabilities and odds ratios: A geometric programming approach

    Directory of Open Access Journals (Sweden)

    D. L. Bricker

    1997-01-01

    Full Text Available The problem of assigning cell probabilities to maximize a multinomial likelihood with order restrictions on the probabilies and/or restrictions on the local odds ratios is modeled as a posynomial geometric program (GP, a class of nonlinear optimization problems with a well-developed duality theory and collection of algorithms. (Local odds ratios provide a measure of association between categorical random variables. A constrained multinomial MLE example from the literature is solved, and the quality of the solution is compared with that obtained by the iterative method of El Barmi and Dykstra, which is based upon Fenchel duality. Exploiting the proximity of the GP model of MLE problems to linear programming (LP problems, we also describe as an alternative, in the absence of special-purpose GP software, an easily implemented successive LP approximation method for solving this class of MLE problems using one of the readily available LP solvers.

  6. Inclinations of small quiet-Sun magnetic features based on a new geometric approach

    CERN Document Server

    Jafarzadeh, S; Lagg, A; Rubio, L R Bellot; van Noort, M; Feller, A; Danilovic, S

    2014-01-01

    High levels of horizontal magnetic flux have been reported in the quiet-Sun internetwork, often based on Stokes profile inversions. Here we introduce a new method for deducing the inclination of magnetic elements and use it to test magnetic field inclinations from inversions. We determine accurate positions of a set of small, bright magnetic elements in high spatial resolution images sampling different photospheric heights obtained by the Sunrise balloon-borne solar observatory. Together with estimates of the formation heights of the employed spectral bands, these provide us with the inclinations of the magnetic features. We also compute the magnetic inclination angle of the same magnetic features from the inversion of simultaneously recorded Stokes parameters. Our new, geometric method returns nearly vertical fields (average inclination of around 14 deg with a relatively narrow distribution having a standard deviation of 6 deg). In strong contrast to this, the traditionally used inversions give almost horizo...

  7. Stellar Open Clusters' Membership Probabilities: an N-Dimensional Geometrical Approach

    CERN Document Server

    Sampedro, Laura

    2016-01-01

    We present a new geometrical method aimed at determining the members of open clusters. The methodology estimates, in an N-dimensional space, the membership probabilities by means of the distances between every star and the cluster central overdensity. It can handle different sets of variables, which have to satisfy the simple condition of being more densely distributed for the cluster members than for the field stars (as positions, proper motions, radial velocities and/or parallaxes are). Unlike other existing techniques, this fact makes the method more flexible and so can be easily applied to different datasets. To quantify how the method identifies the clus- ter members, we design series of realistic simulations recreating sky regions in both position and proper motion subspaces populated by clusters and field stars. The re- sults, using different simulated datasets (N = 1, 2 and 4 variables), show that the method properly recovers a very high fraction of simulated cluster members, with a low number of misc...

  8. A geometric approach to modeling of four- and five-link planar snake-like robot

    Directory of Open Access Journals (Sweden)

    Tomáš Lipták

    2016-10-01

    Full Text Available The article deals with the issue of use of geometric mechanics tools in modelling nonholonomic systems. The introductory part of the article contains fiber bundle theory that we use at creating mathematical model of nonholonomic locomotion system with undulatory movement. Further the determination of general mathematical model for n-link snake-like robot is presented, where we used nonholonomic constraints. The relation between changes of shape and position variables was expressed using the local connection that was used to analyze and control system movement by vector fields. The effect of links number of snake-like robot on its mathematical model was investigated. The last part of this article consists of detailed description of modeling reconstruction equation for four- and five-link snake-like robot.

  9. Morphometric Identification of Queens, Workers and Intermediates in In Vitro Reared Honey Bees (Apis mellifera)

    Science.gov (United States)

    A. De Souza, Daiana; Wang, Ying; Kaftanoglu, Osman; De Jong, David; V. Amdam, Gro; S. Gonçalves, Lionel; M. Francoy, Tiago

    2015-01-01

    In vitro rearing is an important and useful tool for honey bee (Apis mellifera L.) studies. However, it often results in intercastes between queens and workers, which are normally are not seen in hive-reared bees, except when larvae older than three days are grafted for queen rearing. Morphological classification (queen versus worker or intercastes) of bees produced by this method can be subjective and generally depends on size differences. Here, we propose an alternative method for caste classification of female honey bees reared in vitro, based on weight at emergence, ovariole number, spermatheca size and size and shape, and features of the head, mandible and basitarsus. Morphological measurements were made with both traditional morphometric and geometric morphometrics techniques. The classifications were performed by principal component analysis, using naturally developed queens and workers as controls. First, the analysis included all the characters. Subsequently, a new analysis was made without the information about ovariole number and spermatheca size. Geometric morphometrics was less dependent on ovariole number and spermatheca information for caste and intercaste identification. This is useful, since acquiring information concerning these reproductive structures requires time-consuming dissection and they are not accessible when abdomens have been removed for molecular assays or in dried specimens. Additionally, geometric morphometrics divided intercastes into more discrete phenotype subsets. We conclude that morphometric geometrics are superior to traditional morphometrics techniques for identification and classification of honey bee castes and intermediates. PMID:25894528

  10. Performance of the geometric approach to fault detection and isolation in SISO, MISO, SIMO and MIMO systems

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, a geometric approach to fault detection and isolation (FDI) is applied to a Multiple-Input Multiple-Output (MIMO) model of a frame and the FDI results are compared to the ones obtained in the Single-Input Single-Output (SISO), Multiple-Input Single-Output (MISO), and Single-Input Multiple-Output (SIMO) cases. A proper distance function based on parameters obtained from parametric system identification method is used in the geometric approach. ARX (Auto Regressive with eXogenous input) and VARX (Vector ARX) models with 12 parameters are used in all of the above-mentioned models. The obtained results reveal that by increasing the number of inputs, the classification errors reduce, even in the case of applying only one of the inputs in the computations. Furthermore, increasing the number of measured outputs in the FDI scheme results in decreasing classification errors. Also, it is shown that by using probabilistic space in the distance function, fault diagnosis scheme has better performance in comparison with the deterministic one.

  11. Numerical Approach of the Influence of Geometric Properties on the Absorbing in Photonic Crystal

    Directory of Open Access Journals (Sweden)

    A. Merabti

    2016-10-01

    Full Text Available In the proposed study, an investigation has been carried out in order to find a material efficient structure, capable of harnessing maximum solar spectrum. A material efficient structure designed using a one dimensional photonic crystal (1D PC for amorphous silicon. Silicon material is used as it leads to environmental friendly design. The principal objective of this study is to maximize the photon absorption, keeping reflection to a minimum. The influence of geometric parameters on the absorption is studied by using the Finite element method (FEM. The results show that the absorption is affected by the geometry parameters. The optimum parameters of the proposed structure are period (a  480 nm, a filling factor (ff  50 % and depth (d  150 nm. The increase of absorption in the lower region where the wavelengths are around 480 nm, is explained by the reduction of the effective index resulting from the structure of the absorbent layer. For wavelengths between 480 nm and 600 nm, the absorption is directly related to existing Fabry-Perot modes within the absorbent layer. Creating additional absorption peaks at wavelengths above about 600 nm weakly absorbed normally comes from the coupling of the incident light with slow Bloch modes of PC located above the light line.

  12. From face to interface recognition: a differential geometric approach to distinguish DNA from RNA binding surfaces.

    Science.gov (United States)

    Shazman, Shula; Elber, Gershon; Mandel-Gutfreund, Yael

    2011-09-01

    Protein nucleic acid interactions play a critical role in all steps of the gene expression pathway. Nucleic acid (NA) binding proteins interact with their partners, DNA or RNA, via distinct regions on their surface that are characterized by an ensemble of chemical, physical and geometrical properties. In this study, we introduce a novel methodology based on differential geometry, commonly used in face recognition, to characterize and predict NA binding surfaces on proteins. Applying the method on experimentally solved three-dimensional structures of proteins we successfully classify double-stranded DNA (dsDNA) from single-stranded RNA (ssRNA) binding proteins, with 83% accuracy. We show that the method is insensitive to conformational changes that occur upon binding and can be applicable for de novo protein-function prediction. Remarkably, when concentrating on the zinc finger motif, we distinguish successfully between RNA and DNA binding interfaces possessing the same binding motif even within the same protein, as demonstrated for the RNA polymerase transcription-factor, TFIIIA. In conclusion, we present a novel methodology to characterize protein surfaces, which can accurately tell apart dsDNA from an ssRNA binding interfaces. The strength of our method in recognizing fine-tuned differences on NA binding interfaces make it applicable for many other molecular recognition problems, with potential implications for drug design.

  13. Geometric Conversion Approach for the Numerical Evaluation of Hypersingular and Nearly Hypersingular Boundary Integrals over Curved Surface Boundary Elements

    Institute of Scientific and Technical Information of China (English)

    马杭

    2002-01-01

    With the aid of the properties of the hypersingular kernels,a geometric conversion approach was presented in this paper.The conversion leads to a general approach for the accurate and reliable numerical evaluation of the hypersingular surface boundary integrals encountered in a variety of applications with boundary element method.Based on the conversion,the hypersingularity in the boundary integrals could be lowered by one order,resulting in the simplification of the computer code.Moreover,an integral transformation was introduced to damp out the nearly singular behavior of the kernels by the distance function defined in the local polar coordinate system for the nearly hypersingular case.The approach is simple to use,which can be inserted readily to computer code,thus getting rid of the dull routine deduction of formulae before the numerical implementatins,as the expressions of these kernels are in general complicated.The numerical examples were gien in three-dimensional elasticity,verifying the effectiveness of the proposed approach,which makes it possible to observe numerically the behavior of the boundary integral values with hypersingular kernels across the boundary.

  14. Multi-Objective Genetic Algorithm Optimisation Approach for the Geometrical Design of an Active Noise Control Systems

    Directory of Open Access Journals (Sweden)

    N. Jafferi

    2009-09-01

    Full Text Available This paper focuses on the geometrical design of active noise control (ANC in free- field propagation medium. The development and performance assessment uses genetic optimisation techniques to arrange system components so as to satisfy several performance requirements, such as physical extent of cancellation, controller design restriction and system stability. The ANC system design can be effectively addressed if it is considered as multi – objective optimisation problems. The multi-objective genetic algorithms (MOGAs are well suited to the design of an ANC system and the approach used for it is based on a multi - objective method, with which the physical extent of cancellation and relative stability assessment are dealt with simultaneously.

  15. Refining the Indications for the Addition of Orbital Osteotomy during Anterior Cranial Base Approaches: Morphometric and Radiologic Study of the Anterior Cranial Base Osteology.

    Science.gov (United States)

    DeBattista, Juan Carlos; Andaluz, Norberto; Zuccarello, Mario; Kerr, Robert G; Keller, Jeffrey T

    2014-08-01

    Objectives In anatomic and radiologic morphometric studies, we examine a predictive method, based on preoperative imaging of the anterior cranial base, to define when addition of orbital osteotomy is warranted. Design Anatomic and radiographic study. Setting In 100 dry skulls, measurements in the anterior cranial fossa included three lines and two angles based on computerized tomography (CT) scans taken in situ and validated using frameless stereotactic navigation. The medial angle (coronal plane) was the intersection between the highest point of both orbits and the midpoint between the two frontoethmoidal sutures to each orbital roof high point. The oblique angle (sagittal plane) was the intersection at the midpoint of the limbus sphenoidale. Results No identifiable morphometric patterns were found for our classification of anterior fossae; the two-tailed distribution pattern was similar for all skulls, disproving the hypothetical correlation between visual appearance and morphometry. Orbital heights (range: 6.6-18.7 mm) showed a linear relationship with medial and oblique angles, and they had a linear distribution relative to angular increments. Orbital heights > 11 mm were associated with angles ≥ 20 degrees and more likely to benefit from orbitotomy. Conclusion Preoperative CT measurement of orbital height appears feasible for predicting when orbitotomy is needed, and it warrants further testing.

  16. A Geometric Approach to Joint Inversion with Applications to Contaminant Source Zone Characterization

    CERN Document Server

    Aghasi, Alireza; Miller, Eric L; Ramsburg, C Andrew; Abriola, Linda M

    2013-01-01

    This paper presents a new joint inversion approach to shape-based inverse problems. Given two sets of data from distinct physical models, the main objective is to obtain a unified characterization of inclusions within the spatial domain of the physical properties to be reconstructed. Although our proposed method generally applies to many types of inversion problems, the main motivation here is to characterize subsurface contaminant source-zones by processing down gradient hydrological data and cross-gradient electrical resistance tomography (ERT) observations. Inspired by Newton's method for multi-objective optimization, we present an iterative inversion scheme that suggests taking descent steps that can simultaneously reduce both data-model misfit terms. Such an approach, however, requires solving a non-smooth convex problem at every iteration, which is computationally expensive for a pixel-based inversion over the whole domain. Instead, we employ a parametric level set (PaLS) technique that substantially re...

  17. A Hierarchical FEM approach for Simulation of Geometrical and Material induced Instability of Composite Structures

    DEFF Research Database (Denmark)

    Hansen, Anders L.; Lund, Erik; Pinho, Silvestre T.

    2009-01-01

    In this paper a hierarchical FE approach is utilized to simulate delamination in a composite plate loaded in uni-axial compression. Progressive delamination is modelled by use of cohesive interface elements that are automatically embedded. The non-linear problem is solved quasi-statically in which...... the interaction between material degradation and structural instability is solved iteratively. The effect of fibre bridging is studied numerically and in-plane failure is predicted using physically based failure criteria....

  18. A new design approach based on differential evolution algorithm for geometric optimization of magnetorheological brakes

    Science.gov (United States)

    Le-Duc, Thang; Ho-Huu, Vinh; Nguyen-Thoi, Trung; Nguyen-Quoc, Hung

    2016-12-01

    In recent years, various types of magnetorheological brakes (MRBs) have been proposed and optimized by different optimization algorithms that are integrated in commercial software such as ANSYS and Comsol Multiphysics. However, many of these optimization algorithms often possess some noteworthy shortcomings such as the trap of solutions at local extremes, or the limited number of design variables or the difficulty of dealing with discrete design variables. Thus, to overcome these limitations and develop an efficient computation tool for optimal design of the MRBs, an optimization procedure that combines differential evolution (DE), a gradient-free global optimization method with finite element analysis (FEA) is proposed in this paper. The proposed approach is then applied to the optimal design of MRBs with different configurations including conventional MRBs and MRBs with coils placed on the side housings. Moreover, to approach a real-life design, some necessary design variables of MRBs are considered as discrete variables in the optimization process. The obtained optimal design results are compared with those of available optimal designs in the literature. The results reveal that the proposed method outperforms some traditional approaches.

  19. Numerical optimization approach to modelling delamination and buckling of geometrically constrained structures.

    Science.gov (United States)

    Mullineux, G; Hicks, B J; Berry, C

    2012-04-28

    Understanding what happens in terms of delamination during buckling of laminate materials is of importance across a range of engineering sectors. Normally concern is that the strength of the material is not significantly impaired. Carton-board is a material with a laminate structure and, in the initial creation of carton nets, the board is creased in order to weaken the structure. This means that when the carton is eventually folded into its three-dimensional form, correct folding occurs along the weakened crease lines. Understanding what happens during creasing and folding is made difficult by the nonlinear nature of the material properties. This paper considers a simplified approach which extends the idea of minimizing internal energy so that the effects of delamination can be handled. This allows a simulation which reproduces the form of buckling-delamination observed in practice and the form of the torque-rotation relation.

  20. "Improved Geometric Network Model" (IGNM): a novel approach for deriving Connectivity Graphs for Indoor Navigation

    Science.gov (United States)

    Mortari, F.; Zlatanova, S.; Liu, L.; Clementini, E.

    2014-04-01

    Over the past few years Personal Navigation Systems have become an established tool for route planning, but they are mainly designed for outdoor environments. Indoor navigation is still a challenging research area for several reasons: positioning is not very accurate, users can freely move between the interior boundaries of buildings, path network construction process may not be easy and straightforward due to complexity of indoor space configurations. Therefore the creation of a good network is essential for deriving overall connectivity of a building and for representing position of objects within the environment. This paper reviews current approaches to automatic derivation of route graphs for indoor navigation and discusses some of their limitations. Then, it introduces a novel algorithmic strategy for extracting a 3D connectivity graph for indoor navigation based on 2D floor plans.

  1. Analysis of epistatic interactions and fitness landscapes using a new geometric approach

    Directory of Open Access Journals (Sweden)

    Elena Santiago F

    2007-04-01

    Full Text Available Abstract Background Understanding interactions between mutations and how they affect fitness is a central problem in evolutionary biology that bears on such fundamental issues as the structure of fitness landscapes and the evolution of sex. To date, analyses of fitness landscapes have focused either on the overall directional curvature of the fitness landscape or on the distribution of pairwise interactions. In this paper, we propose and employ a new mathematical approach that allows a more complete description of multi-way interactions and provides new insights into the structure of fitness landscapes. Results We apply the mathematical theory of gene interactions developed by Beerenwinkel et al. to a fitness landscape for Escherichia coli obtained by Elena and Lenski. The genotypes were constructed by introducing nine mutations into a wild-type strain and constructing a restricted set of 27 double mutants. Despite the absence of mutants higher than second order, our analysis of this genotypic space points to previously unappreciated gene interactions, in addition to the standard pairwise epistasis. Our analysis confirms Elena and Lenski's inference that the fitness landscape is complex, so that an overall measure of curvature obscures a diversity of interaction types. We also demonstrate that some mutations contribute disproportionately to this complexity. In particular, some mutations are systematically better than others at mixing with other mutations. We also find a strong correlation between epistasis and the average fitness loss caused by deleterious mutations. In particular, the epistatic deviations from multiplicative expectations tend toward more positive values in the context of more deleterious mutations, emphasizing that pairwise epistasis is a local property of the fitness landscape. Finally, we determine the geometry of the fitness landscape, which reflects many of these biologically interesting features. Conclusion A full

  2. Geometric Simulation Approach for Grading and Assessing the Thermostability of CALBs

    Directory of Open Access Journals (Sweden)

    B. Senthilkumar

    2016-01-01

    Full Text Available Candida antarctica lipase B (CALB is a known stable and highly active enzyme used widely in biodiesel synthesis. In this work, the stability of native (4K6G and mutant (4K5Q CALB was studied through various structural parameters using conformational sampling approach. The contours of polar surface area and surface area of mutant CALB were 11357.67 Å2 and 30007.4 Å2, respectively, showing an enhanced stability compared to native CALB with a statistically significant P value of < 0.0001. Moreover, simulated thermal denaturation of CALB, a process involving dilution of hydrogen bond, significantly shielded against different intervals of energy application in mutant CALB revealing its augmentation of structural rigidity against native CALB. Finally, computational docking analysis showed an increase in the binding affinity of CALB and its substrate (triglyceride in mutant CALB with Atomic Contact Energy (ACE of −91.23 kcal/mol compared to native CALB (ACE of −70.3 kcal/mol. The computational observations proposed that the use of mutant CALB (4K5Q could serve as a best template for production of biodiesel in the future. Additionally, it can also be used as a template to identify efficient thermostable lipases through further mutations.

  3. Colliding with G2 near the Galactic Centre: a geometrical approach

    CERN Document Server

    Marcos, R de la Fuente

    2013-01-01

    The object G2 will pass within nearly 100 au from Sgr A* in 2014. Due to its very short periapse, the study of the dynamical evolution of this object in the short-term future may offer some insight into the region surrounding the supermassive black hole at the centre of the Galaxy. With this scenario in mind, it has recently been proposed by Bartos et al. (arXiv:1302.3220) that, prior to its perinigricon, G2 will likely experience multiple encounters with members of the black hole and neutron star populations believed to orbit near the Galactic Centre. Here, we further explore this possibility and study the general case for collisions with the G2 object using the latest orbital solutions provided by Phifer et al. (arXiv:1304.5280) and Gillessen et al., (arXiv:1306.1374) and a Monte Carlo approach to estimate the minimum orbit intersection distance (MOID) with G2 as a function of the orbital parameters of the incoming body. Our results indicate that encounters at distances closer than 100 au started to become ...

  4. A NURBS-based finite element model applied to geometrically nonlinear elastodynamics using a corotational approach

    KAUST Repository

    Espath, L. F R

    2015-02-03

    A numerical model to deal with nonlinear elastodynamics involving large rotations within the framework of the finite element based on NURBS (Non-Uniform Rational B-Spline) basis is presented. A comprehensive kinematical description using a corotational approach and an orthogonal tensor given by the exact polar decomposition is adopted. The state equation is written in terms of corotational variables according to the hypoelastic theory, relating the Jaumann derivative of the Cauchy stress to the Eulerian strain rate.The generalized-α method (Gα) method and Generalized Energy-Momentum Method with an additional parameter (GEMM+ξ) are employed in order to obtain a stable and controllable dissipative time-stepping scheme with algorithmic conservative properties for nonlinear dynamic analyses.The main contribution is to show that the energy-momentum conservation properties and numerical stability may be improved once a NURBS-based FEM in the spatial discretization is used. Also it is shown that high continuity can postpone the numerical instability when GEMM+ξ with consistent mass is employed; likewise, increasing the continuity class yields a decrease in the numerical dissipation. A parametric study is carried out in order to show the stability and energy budget in terms of several properties such as continuity class, spectral radius and lumped as well as consistent mass matrices.

  5. ROUNDSCALE SPEARFISH branchiostegal morphometric data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The morphometric characteristics that separate white marlin Kajikia albidus from roundscale spearfish Tetrapturus georgii can be difficult for non-experts to...

  6. Spatio-Temporal Constrained Human Trajectory Generation from the PIR Motion Detector Sensor Network Data: A Geometric Algebra Approach.

    Science.gov (United States)

    Yu, Zhaoyuan; Yuan, Linwang; Luo, Wen; Feng, Linyao; Lv, Guonian

    2015-12-30

    Passive infrared (PIR) motion detectors, which can support long-term continuous observation, are widely used for human motion analysis. Extracting all possible trajectories from the PIR sensor networks is important. Because the PIR sensor does not log location and individual information, none of the existing methods can generate all possible human motion trajectories that satisfy various spatio-temporal constraints from the sensor activation log data. In this paper, a geometric algebra (GA)-based approach is developed to generate all possible human trajectories from the PIR sensor network data. Firstly, the representation of the geographical network, sensor activation response sequences and the human motion are represented as algebraic elements using GA. The human motion status of each sensor activation are labeled using the GA-based trajectory tracking. Then, a matrix multiplication approach is developed to dynamically generate the human trajectories according to the sensor activation log and the spatio-temporal constraints. The method is tested with the MERL motion database. Experiments show that our method can flexibly extract the major statistical pattern of the human motion. Compared with direct statistical analysis and tracklet graph method, our method can effectively extract all possible trajectories of the human motion, which makes it more accurate. Our method is also likely to provides a new way to filter other passive sensor log data in sensor networks.

  7. Estimating 3D gaze in physical environment: a geometric approach on consumer-level remote eye tracker

    Science.gov (United States)

    Wibirama, Sunu; Mahesa, Rizki R.; Nugroho, Hanung A.; Hamamoto, Kazuhiko

    2017-02-01

    Remote eye trackers with consumer price have been used for various applications on flat computer screen. On the other hand, 3D gaze tracking in physical environment has been useful for visualizing gaze behavior, robots controller, and assistive technology. Instead of using affordable remote eye trackers, 3D gaze tracking in physical environment has been performed using corporate-level head mounted eye trackers, limiting its practical usage to niche user. In this research, we propose a novel method to estimate 3D gaze using consumer-level remote eye tracker. We implement geometric approach to obtain 3D point of gaze from binocular lines-of-sight. Experimental results show that the proposed method yielded low errors of 3.47+/-3.02 cm, 3.02+/-1.34 cm, and 2.57+/-1.85 cm in X, Y , and Z dimensions, respectively. The proposed approach may be used as a starting point for designing interaction method in 3D physical environment.

  8. Spatio-Temporal Constrained Human Trajectory Generation from the PIR Motion Detector Sensor Network Data: A Geometric Algebra Approach

    Directory of Open Access Journals (Sweden)

    Zhaoyuan Yu

    2015-12-01

    Full Text Available Passive infrared (PIR motion detectors, which can support long-term continuous observation, are widely used for human motion analysis. Extracting all possible trajectories from the PIR sensor networks is important. Because the PIR sensor does not log location and individual information, none of the existing methods can generate all possible human motion trajectories that satisfy various spatio-temporal constraints from the sensor activation log data. In this paper, a geometric algebra (GA-based approach is developed to generate all possible human trajectories from the PIR sensor network data. Firstly, the representation of the geographical network, sensor activation response sequences and the human motion are represented as algebraic elements using GA. The human motion status of each sensor activation are labeled using the GA-based trajectory tracking. Then, a matrix multiplication approach is developed to dynamically generate the human trajectories according to the sensor activation log and the spatio-temporal constraints. The method is tested with the MERL motion database. Experiments show that our method can flexibly extract the major statistical pattern of the human motion. Compared with direct statistical analysis and tracklet graph method, our method can effectively extract all possible trajectories of the human motion, which makes it more accurate. Our method is also likely to provides a new way to filter other passive sensor log data in sensor networks.

  9. Geometrical Bioelectrodynamics

    CERN Document Server

    Ivancevic, Vladimir G

    2008-01-01

    This paper proposes rigorous geometrical treatment of bioelectrodynamics, underpinning two fast-growing biomedical research fields: bioelectromagnetism, which deals with the ability of life to produce its own electromagnetism, and bioelectromagnetics, which deals with the effect on life from external electromagnetism. Keywords: Bioelectrodynamics, exterior geometrical machinery, Dirac-Feynman quantum electrodynamics, functional electrical stimulation

  10. Sperm kinematic, head morphometric and kinetic-morphometric subpopulations in the blue fox (Alopex lagopus

    Directory of Open Access Journals (Sweden)

    Carles Soler

    2017-01-01

    Full Text Available This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component (PC analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations: SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed: SP1: large oval cells; SP2: medium size elongated cells; and SP3: small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations - SP1: high oscillatory motility, large and short heads; SP2: medium velocity with small and short heads; SP3: slow motion small and elongated cells; and SP4: high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans.

  11. Sperm kinematic, head morphometric and kinetic-morphometric subpopulations in the blue fox (Alopex lagopus)

    Science.gov (United States)

    Soler, Carles; Contell, Jesús; Bori, Lorena; Sancho, María; García-Molina, Almudena; Valverde, Anthony; Segarvall, Jan

    2017-01-01

    This work provides information on the blue fox ejaculated sperm quality needed for seminal dose calculations. Twenty semen samples, obtained by masturbation, were analyzed for kinematic and morphometric parameters by using CASA-Mot and CASA-Morph system and principal component (PC) analysis. For motility, eight kinematic parameters were evaluated, which were reduced to PC1, related to linear variables, and PC2, related to oscillatory movement. The whole population was divided into three independent subpopulations: SP1, fast cells with linear movement; SP2, slow cells and nonoscillatory motility; and SP3, medium speed cells and oscillatory movement. In almost all cases, the subpopulation distribution by animal was significantly different. Head morphology analysis generated four size and four shape parameters, which were reduced to PC1, related to size, and PC2, related to shape of the cells. Three morphometric subpopulations existed: SP1: large oval cells; SP2: medium size elongated cells; and SP3: small and short cells. The subpopulation distribution differed between animals. Combining the kinematic and morphometric datasets produced PC1, related to morphometric parameters, and PC2, related to kinematics, which generated four sperm subpopulations – SP1: high oscillatory motility, large and short heads; SP2: medium velocity with small and short heads; SP3: slow motion small and elongated cells; and SP4: high linear speed and large elongated cells. Subpopulation distribution was different in all animals. The establishment of sperm subpopulations from kinematic, morphometric, and combined variables not only improves the well-defined fox semen characteristics and offers a good conceptual basis for fertility and sperm preservation techniques in this species, but also opens the door to use this approach in other species, included humans. PMID:27751987

  12. Modeling the Influence of Antifreeze Proteins on Three-Dimensional Ice Crystal Melt Shapes using a Geometric Approach

    CERN Document Server

    Liu, Jun Jie; Dolev, Maya Bar; Celik, Yeliz; Wettlaufer, J S; Braslavsky, Ido

    2012-01-01

    The melting of pure axisymmetric ice crystals has been described previously by us within the framework of so-called geometric crystal growth. Nonequilibrium ice crystal shapes evolving in the presence of hyperactive antifreeze proteins (hypAFPs) are experimentally observed to assume ellipsoidal geometries ("lemon" or "rice" shapes). To analyze such shapes we harness the underlying symmetry of hexagonal ice Ih and extend two-dimensional geometric models to three-dimensions to reproduce the experimental dissolution process. The geometrical model developed will be useful as a quantitative test of the mechanisms of interaction between hypAFPs and ice.

  13. Measuring the Student Group Capacity for Obtaining Geometric Information in the van Hiele Developmental Thought Process:A Fuzzy Approach

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The student group possibilistic uncertainty in the van Hiele process of geometric reasoning is considered as the student group capacity for obtaining geometric information. Hence, the student group capacity for obtaining geometric information can be measured by the total possibilistic uncertainty T(r) of an ordered possibility distribution. The capacities of three student groups are found by calculating the total possibilistic uncertainties of these groups. These capacity values set an expectation of future group performance. Future research indications of how the total possibilistic uncertainty may be applied to other models of learning and development will help to establish it as a viable measure in educational psychology.

  14. GEOMETRIC TURBULENCE

    Directory of Open Access Journals (Sweden)

    Trunev A. P.

    2014-05-01

    Full Text Available In this article we have investigated the solutions of Maxwell's equations, Navier-Stokes equations and the Schrödinger associated with the solutions of Einstein's equations for empty space. It is shown that in some cases the geometric instability leading to turbulence on the mechanism of alternating viscosity, which offered by N.N. Yanenko. The mechanism of generation of matter from dark energy due to the geometric turbulence in the Big Bang has been discussed

  15. Synchronization of integral and fractional order chaotic systems a differential algebraic and differential geometric approach with selected applications in real-time

    CERN Document Server

    Martínez-Guerra, Rafael; Gómez-Cortés, Gian Carlo

    2015-01-01

    This book provides a general overview of several concepts of synchronization and brings together related approaches to secure communication in chaotic systems. This is achieved using a combination of analytic, algebraic, geometrical and asymptotical methods to tackle the dynamical feedback stabilization problem. In particular, differential-geometric and algebraic differential concepts reveal important structural properties of chaotic systems and serve as guide for the construction of design procedures for a wide variety of chaotic systems. The basic differential algebraic and geometric concepts are presented in the first few chapters in a novel way as design tools, together with selected experimental studies demonstrating their importance. The subsequent chapters treat recent applications. Written for graduate students in applied physical sciences, systems engineers, and applied mathematicians interested in synchronization of chaotic systems and in secure communications, this self-contained text requires only...

  16. The Sambungmacan 3 Homo erectus calvaria: a comparative morphometric and morphological analysis.

    Science.gov (United States)

    Delson, E; Harvati, K; Reddy, D; Marcus, L F; Mowbray, K; Sawyer, G J; Jacob, T; Márquez, S

    2001-04-01

    The Sambungmacan (Sm) 3 calvaria, discovered on Java in 1977, was illegally removed from Indonesia in 1998 and appeared in New York City in early 1999 at the Maxilla & Mandible, Ltd. natural history shop. Here we undertake an analysis of its phylogenetic and systematic position using geometric morphometrics and comparative morphology. The coordinates of points in the sagittal plane from glabella to opisthion were resampled to yield "lines" of 50 semi-landmarks. Coordinates of glabella, bregma, lambda, inion, and opisthion were also collected and analyzed separately. Casts of Homo erectus fossils from Indonesia, China, and Kenya and of "archaic H. sapiens" from Kabwe and Petralona, as well as 10 modern human crania, were used as the primary comparative sample. The modern humans were well separated from the fossils in a graphical superimposition of Procrustes-aligned semi-landmarks as well as in principal component and canonical discriminant analyses. In all of these, Sm 3 falls intermediate between the fossil and modern groups. Morphological comparisons of Sm 3 with a selection of Homo erectus fossils revealed its greatest similarity to specimens from Ngandong and the Sm 1 calvaria. Compared to all other H. erectus, Sm 3 was distinctive in its more vertical supratoral plane, less anteriorly projecting glabella and less sharply angled occiput. In these features it was somewhat similar to modern humans. It is not yet possible to determine if this similarity implies an evolutionary relationship or (more likely) individual or local populational variation. Several features of Sm 3 (small size, gracile supraorbital torus and lack of angular torus, and position in principal component analysis) suggest that it was a female. The use of geometric morphometrics provides a means to statistically test the shapes of such fossils in a manner not easily duplicated by other methods. The intermediate position of Sm 3 between fossil and modern samples in several different subanalyses

  17. Algebro-geometric approach for a centrally extended Uq[sl(2|2)] R-matrix

    Science.gov (United States)

    Martins, M. J.

    2017-04-01

    In this paper we investigate the algebraic geometric nature of a solution of the Yang-Baxter equation based on the quantum deformation of the centrally extended sl (2 | 2) superalgebra proposed by Beisert and Koroteev [1]. We derive an alternative representation for the R-matrix in which the matrix elements are given in terms of rational functions depending on weights sited on a degree six surface. For generic gauge the weights geometry are governed by a genus one ruled surface while for a symmetric gauge choice the weights lie instead on a genus five curve. We have written down the polynomial identities satisfied by the R-matrix entries needed to uncover the corresponding geometric properties. For arbitrary gauge the R-matrix geometry is argued to be birational to the direct product CP1 ×CP1 × A where A is an Abelian surface. For the symmetric gauge we present evidences that the geometric content is that of a surface of general type lying on the so-called Severi line with irregularity two and geometric genus nine. We discuss potential geometric degenerations when the two free couplings are restricted to certain one-dimensional subspaces.

  18. Geometric mechanics

    CERN Document Server

    Muniz Oliva, Waldyr

    2002-01-01

    Geometric Mechanics here means mechanics on a pseudo-riemannian manifold and the main goal is the study of some mechanical models and concepts, with emphasis on the intrinsic and geometric aspects arising in classical problems. The first seven chapters are written in the spirit of Newtonian Mechanics while the last two ones as well as two of the four appendices describe the foundations and some aspects of Special and General Relativity. All the material has a coordinate free presentation but, for the sake of motivation, many examples and exercises are included in order to exhibit the desirable flavor of physical applications.

  19. Threatened Neotropical mollusks: analysis of shape differences in three endemic snails from High Paraná River by geometric morphometrics Moluscos neotropicales amenazados: análisis de diferencias de forma en tres caracoles endémicos del río Alto Paraná mediante morfometría geométrica

    Directory of Open Access Journals (Sweden)

    Roberto E. Vogler

    2012-12-01

    Full Text Available Variation in shape among a living and 2 extinct aquatic snails of the genus Aylacostoma, using a geometric morphometric method of thin plate splines and multivariate analysis was investigated. The analysis was performed to evaluate the diagnostic capability of this method and to explore shell shape differences, due to the lack of other data, in an attempt to answer why only 1 of the species persisted in the wild. Sixteen landmarks in a bi-dimensional space for 32 shells of type, paratype and reference specimens deposited in museums of Argentina were defined. Analysis was successful in assigning individual specimens to particular species. Statistically significant differences in last whorl, aperture, and spire were found for the first 4 non-uniform components explaining an 85% of local variation observed. Differences could be related to a differential use of habitat and/or to the degree of exposure to water current. More globose shell found in the extinct species could be associated to habitats and substrata with the highest water currents, whereas the more stylized shell in the third species could be related to a preference for more protected habitats, like those where it presently occurs.La variación de forma entre una especie viviente y dos extintas de caracoles acuáticos del género Aylacostoma, fue investigada mediante el método de morfometría geométrica de "thin plate splines" y análisis multivariado. El análisis se realizó para evaluar la capacidad diagnóstica del método y explorar las diferencias de forma de conchilla, debido a la falta de otros datos, en un intento por responder por qué sólo una de las especies persistió en la naturaleza. Dieciséis "landmarks" fueron definidos en un espacio bi-dimensional para 32 conchillas de ejemplares tipo, paratipo y de referencia depositados en museos de Argentina. El análisis fue exitoso en la asignación de los individuos a especies particulares. Se encontraron diferencias

  20. A robust inverse approach for estimating the magnetic material properties of an electromagnetic device with minimum influence of the uncertainty in the geometrical parameters

    OpenAIRE

    Mohamed Abouelyazied Abdallh, Ahmed; Crevecoeur, Guillaume; Dupré, Luc

    2011-01-01

    The magnetic properties of the magnetic circuit of an electromagnetic device (EMD) can be identified by solving an inverse problem, where sets of measurements are properly interpreted using a forward numerical model of the device. However, the uncertainties of the geometrical parameter values in the forward model result in recovery errors in the reconstructed material parameter values. This paper proposes a novel inverse approach technique, in which the propagations of the uncertainties in th...

  1. Variability of worked examples and transfer of geometrical problem-solving skills : a cognitive-load approach

    NARCIS (Netherlands)

    Paas, Fred G.W.C.; van Merrienboer, Jeroen J.G.; van Merrienboer, J.J.G.

    1994-01-01

    Four computer-based training strategies for geometrical problem solving in the domain of computer numerically controlled machinery programming were studied with regard to their effects on training performance, transfer performance, and cognitive load. A low- and a high-variability conventional

  2. Geometric Algebra

    CERN Document Server

    Chisolm, Eric

    2012-01-01

    This is an introduction to geometric algebra, an alternative to traditional vector algebra that expands on it in two ways: 1. In addition to scalars and vectors, it defines new objects representing subspaces of any dimension. 2. It defines a product that's strongly motivated by geometry and can be taken between any two objects. For example, the product of two vectors taken in a certain way represents their common plane. This system was invented by William Clifford and is more commonly known as Clifford algebra. It's actually older than the vector algebra that we use today (due to Gibbs) and includes it as a subset. Over the years, various parts of Clifford algebra have been reinvented independently by many people who found they needed it, often not realizing that all those parts belonged in one system. This suggests that Clifford had the right idea, and that geometric algebra, not the reduced version we use today, deserves to be the standard "vector algebra." My goal in these notes is to describe geometric al...

  3. Geometry of mixed states and degeneracy structure of geometric phases for multi-level quantum systems. A unitary group approach

    CERN Document Server

    Ercolessi, E; Morandi, G; Mukunda, N

    2001-01-01

    We analyze the geometric aspects of unitary evolution of general states for a multilevel quantum system by exploiting the structure of coadjoint orbits in the unitary group Lie algebra. Using the same method in the case of SU(3) we study the effect of degeneracies on geometric phases for three-level systems. This is shown to lead to a highly nontrivial generalization of the result for two-level systems in which degeneracy results in a "monopole" structure in parameter space. The rich structures that arise are related to the geometry of adjoint orbits in SU(3). The limiting case of a two-level degeneracy in a three-level system is shown to lead to the known monopole structure.

  4. Agustin de Betancourt’s Wind Machine for Draining Marshy Ground: Approach to Its Geometric Modeling with Autodesk Inventor Professional

    Directory of Open Access Journals (Sweden)

    José Ignacio Rojas-Sola

    2016-12-01

    Full Text Available The present study shows the process followed in making the three-dimensional model and geometric documentation of a historical invention of the renowned Spanish engineer Agustin de Betancourt y Molina, which forms part of his rich legacy. Specifically, this was a wind machine for draining marshy ground, designed in 1789. The present research relies on the computer-aided design (CAD techniques using Autodesk Inventor Professional software, based on the scant information provided by the only two drawings of the machine, making it necessary to propose a number of dimensional and geometric hypotheses as well as a series of movement restrictions (degrees of freedom, to arrive at a consistent design. The results offer a functional design for this historic invention.

  5. Morphometric characterization of sub-basins in the municipality of Xapuri: subsidies to land management in the Western Amazon

    Directory of Open Access Journals (Sweden)

    Éllen Albuquerque Abud

    2015-04-01

    Full Text Available This work morphometrically characterized watersheds that occur in the municipality of Xapuri and constructed a model that explains the extent of watershed impact and resilience. Emphasis was given to provide a decision-making tool for non-specialists. The study area is located in the State of Acre and has four sub-basins: Alto Acre, Rio Xapuri, Xipamanu and Riozinho do Rola. A cartographic survey was conducted, to include the morphometric characteristics of the area and land use and cover features that resulted in the soil-hydrographic zoning of the municipality. Sub-basins Xapuri, Xipamanu and Riozinho do Rôla revealed drainage densities and orders that indicate low drainage efficiency, while Alto Acre presented high drainage orders (ninth order and densities, contrary the geometric indices and drainage densities, and is considered to have efficient drainage. Considerable alterations in permanent preservation areas occur in the municipality of Xapuri, with conversion to less resilient areas highly sensitive to impacts. The soil-hydrographic zoning assists in visualizing the municipality in a land management context through an ecosystem approach and a qualitative view of the possibilities and weaknesses.

  6. Morphometric differences and fluctuating asymmetry in Melipona subnitida Ducke 1910 (Hymenoptera: Apidae in different types of housing

    Directory of Open Access Journals (Sweden)

    C. B. S. Lima

    Full Text Available Abstract A geometric morphometrics approach was applied to evaluate differences in forewing patterns of the Jandaira bee (Melipona subnitida Ducke. For this, we studied the presence of fluctuating asymmetry (FA in forewing shape and size of colonies kept in either rational hive boxes or natural tree trunks. We detected significant FA for wing size as well as wing shape independent of the type of housing (rational box or tree trunks, indicating the overall presence of stress during the development of the studied specimens. FA was also significant (p < 0.01 between rational boxes, possibly related to the use of various models of rational boxes used for keeping stingless bees. In addition, a Principal Component Analysis indicated morphometric variation between bee colonies kept in either rational hive boxes or in tree trunks, that may be related to the different origins of the bees: tree trunk colonies were relocated natural colonies while rational box colonies originated from multiplying other colonies. We conclude that adequate measures should be taken to reduce the amount of stress during bee handling by using standard models of rational boxes that cause the least disruption.

  7. Non-iterative geometric approach for inverse kinematics of redundant lead-module in a radiosurgical snake-like robot.

    Science.gov (United States)

    Omisore, Olatunji Mumini; Han, Shipeng; Ren, Lingxue; Zhang, Nannan; Ivanov, Kamen; Elazab, Ahmed; Wang, Lei

    2017-08-01

    Snake-like robot is an emerging form of serial-link manipulator with the morphologic design of biological snakes. The redundant robot can be used to assist medical experts in accessing internal organs with minimal or no invasion. Several snake-like robotic designs have been proposed for minimal invasive surgery, however, the few that were developed are yet to be fully explored for clinical procedures. This is due to lack of capability for full-fledged spatial navigation. In rare cases where such snake-like designs are spatially flexible, there exists no inverse kinematics (IK) solution with both precise control and fast response. In this study, we proposed a non-iterative geometric method for solving IK of lead-module of a snake-like robot designed for therapy or ablation of abdominal tumors. The proposed method is aimed at providing accurate and fast IK solution for given target points in the robot's workspace. n-1 virtual points (VPs) were geometrically computed and set as coordinates of intermediary joints in an n-link module. Suitable joint angles that can place the end-effector at given target points were then computed by vectorizing coordinates of the VPs, in addition to coordinates of the base point, target point, and tip of the first link in its default pose. The proposed method is applied to solve IK of two-link and redundant four-link modules. Both two-link and four-link modules were simulated with Robotics Toolbox in Matlab 8.3 (R2014a). Implementation result shows that the proposed method can solve IK of the spatially flexible robot with minimal error values. Furthermore, analyses of results from both modules show that the geometric method can reach 99.21 and 88.61% of points in their workspaces, respectively, with an error threshold of 1 mm. The proposed method is non-iterative and has a maximum execution time of 0.009 s. This paper focuses on solving IK problem of a spatially flexible robot which is part of a developmental project for abdominal

  8. A Discrete Time Queueing Approach to Model and Evaluate Slotted Ring Network Buffer using Matrix Geometric Method

    Directory of Open Access Journals (Sweden)

    Syed Asif Ali Shah

    2011-01-01

    Full Text Available Assorted analytical methods have been proposed for evaluating the performance of a slotted ring network. This paper proposes MGM (Matrix Geometric Method to analyze the station buffer of a slotted ring for DT (Discrete-Time queueing. The slotted ring is analyzed for infinite station buffer as a late arrival DT system. Utilizing the characteristics of 2-D Markov chain, various performance measures are validated with their corresponding results such as, throughput and MPAD (Mean Packet Access Delay as well as the packet rejection probability for finite station buffer. The presented results prove efficacy of the method.

  9. Morphometric Wing Characters as a Tool for Mosquito Identification

    Science.gov (United States)

    Christe, Rafael de Oliveira; Multini, Laura Cristina; Vidal, Paloma Oliveira; Wilk-da-Silva, Ramon; de Carvalho, Gabriela Cristina; Marrelli, Mauro Toledo

    2016-01-01

    Mosquitoes are responsible for the transmission of important infectious diseases, causing millions of deaths every year and endangering approximately 3 billion people around the world. As such, precise identification of mosquito species is crucial for an understanding of epidemiological patterns of disease transmission. Currently, the most common method of mosquito identification relies on morphological taxonomic keys, which do not always distinguish cryptic species. However, wing geometric morphometrics is a promising tool for the identification of vector mosquitoes, sibling and cryptic species included. This study therefore sought to accurately identify mosquito species from the three most epidemiologically important mosquito genera using wing morphometrics. Twelve mosquito species from three epidemiologically important genera (Aedes, Anopheles and Culex) were collected and identified by taxonomic keys. Next, the right wing of each adult female mosquito was removed and photographed, and the coordinates of eighteen digitized landmarks at the intersections of wing veins were collected. The allometric influence was assessed, and canonical variate analysis and thin-plate splines were used for species identification. Cross-validated reclassification tests were performed for each individual, and a Neighbor Joining tree was constructed to illustrate species segregation patterns. The analyses were carried out and the graphs plotted with TpsUtil 1.29, TpsRelw 1.39, MorphoJ 1.02 and Past 2.17c. Canonical variate analysis for Aedes, Anopheles and Culex genera showed three clear clusters in morphospace, correctly distinguishing the three mosquito genera, and pairwise cross-validated reclassification resulted in at least 99% accuracy; subgenera were also identified correctly with a mean accuracy of 96%, and in 88 of the 132 possible comparisons, species were identified with 100% accuracy after the data was subjected to reclassification. Our results showed that Aedes, Culex

  10. Additivity Rule for Electron-Molecule Total Cross Section Calculations at 50-5000 eV: A Geometrical Approach

    Institute of Scientific and Technical Information of China (English)

    SHI De-Heng; SUN Jin-Feng; MA Heng; ZHU Zun-Lue; YANG Xiang-Dong

    2007-01-01

    To quantify the changes of the geometric shielding effect in a molecule as the incident electron energy varies,we present an empirical fraction, which represents the total cross section (TCS) contributions of shielded atoms in a molecule at different energies. Using this empirical fraction, a new formulation of the additivity rule is proposed. Using this new additivity rule, the TCSs for electron scattering by CO2, C2H2, C6H12 (cyclo-hexane) and CsH16 (cyclo-octane) are calculated in the range 50-5000 eV. Here the atomic cross sections are derived from the experimental TCS results of simple molecules (H2, O2, CO). The quantitative TCSs are compared with those obtained by experiments and other theories, and good agreement is attained over a wide energy range.

  11. An Approach to Continuous Approximation of Pareto Front Using Geometric Support Vector Regression for Multi-objective Optimization of Fermentation Process

    Institute of Scientific and Technical Information of China (English)

    Jiahuan Wu; Jianlin Wang; Tao Yu; Liqiang Zhao

    2014-01-01

    The approaches to discrete approximation of Pareto front using multi-objective evolutionary algorithms have the problems of heavy computation burden, long running time and missing Pareto optimal points. In order to overcome these problems, an approach to continuous approximation of Pareto front using geometric support vector regression is presented. The regression model of the small size approximate discrete Pareto front is constructed by geometric support vector regression modeling and is described as the approximate continuous Pareto front. In the process of geometric support vector regression modeling, considering the distribution characteristic of Pareto optimal points, the separable augmented training sample sets are constructed by shifting original training sample points along multiple coordinated axes. Besides, an interactive decision-making (DM) procedure, in which the continuous approximation of Pareto front and decision-making is performed interactive-ly, is designed for improving the accuracy of the preferred Pareto optimal point. The correctness of the continuous approximation of Pareto front is demonstrated with a typical multi-objective optimization problem. In addition, combined with the interactive decision-making procedure, the continuous approximation of Pareto front is applied in the multi-objective optimization for an industrial fed-batch yeast fermentation process. The experi-mental results show that the generated approximate continuous Pareto front has good accuracy and complete-ness. Compared with the multi-objective evolutionary algorithm with large size population, a more accurate preferred Pareto optimal point can be obtained from the approximate continuous Pareto front with less compu-tation and shorter running time. The operation strategy corresponding to the final preferred Pareto optimal point generated by the interactive DM procedure can improve the production indexes of the fermentation process effectively.

  12. New morphometric properties for channel network classification using the graph theory and DEM

    Science.gov (United States)

    Moussa, R.; Colin, F.; Rabotin, M.; A; Crabit

    2012-04-01

    The channel network controls the spatial pattern of hydrological processes within a catchment. Hence the identification of key hydrological features characterising the channel network can contribute to a rational classification of catchments. This presentation aims to investigate morphometric properties of the channel network derived from DEM using the graph theory, and estimate whether these properties can be used as similarity indices for the classification of channel networks. The graph theory was used in order to represent the contributing drainage area which has properties of a scale free network, and was subsequently characterised by highly connected nodes called hubs. The method involves ranking the hubs of a channel network according to the contributing drainage area and the distance to the outlet. The hubs' characteristics can be considered as morphometric descriptors of the channel network and are used to compare and classify channel network. Applications were conducted on 788 French catchments with the same area (between 100 and 105 km2) and on 18 catchments having an area between 43 and 116450 km2. First, we present some newly found invariance properties of headwater subcatchments and show that some invariant morphometric properties characterize only natural channel networks verifying Optimal Channel Networks (OCN) properties, but are not verified for non-OCN (Moussa et al., 2011, Water Resources Research, 47, W08518). A new empirical model based on self-affine properties was developed in order to calculate the number N and the total headwater area H as a function of the cutoff area S used to extract the channel network from DEM. Results show that H(S) / S0 (S0 being the catchment area) is independent from S and seems constant (0.29 +/- 0.03) for various shapes and sizes of channel networks, and consequently can be considered as invariant general descriptor of natural channel networks. On the contrary, this is not the case when the approach is applied

  13. Geometrically Consistent Mesh Modification

    KAUST Repository

    Bonito, A.

    2010-01-01

    A new paradigm of adaptivity is to execute refinement, coarsening, and smoothing of meshes on manifolds with incomplete information about their geometry and yet preserve position and curvature accuracy. We refer to this collectively as geometrically consistent (GC) mesh modification. We discuss the concept of discrete GC, show the failure of naive approaches, and propose and analyze a simple algorithm that is GC and accuracy preserving. © 2010 Society for Industrial and Applied Mathematics.

  14. Securing a cyber physical system in nuclear power plants using least square approximation and computational geometric approach

    Energy Technology Data Exchange (ETDEWEB)

    Gawand, Hemangi Laxman [Homi Bhabha National Institute, Computer Section, BARC, Mumbai (India); Bhattacharjee, A. K. [Reactor Control Division, BARC, Mumbai (India); Roy, Kallol [BHAVINI, Kalpakkam (India)

    2017-04-15

    In industrial plants such as nuclear power plants, system operations are performed by embedded controllers orchestrated by Supervisory Control and Data Acquisition (SCADA) software. A targeted attack (also termed a control aware attack) on the controller/SCADA software can lead a control system to operate in an unsafe mode or sometimes to complete shutdown of the plant. Such malware attacks can result in tremendous cost to the organization for recovery, cleanup, and maintenance activity. SCADA systems in operational mode generate huge log files. These files are useful in analysis of the plant behavior and diagnostics during an ongoing attack. However, they are bulky and difficult for manual inspection. Data mining techniques such as least squares approximation and computational methods can be used in the analysis of logs and to take proactive actions when required. This paper explores methodologies and algorithms so as to develop an effective monitoring scheme against control aware cyber attacks. It also explains soft computation techniques such as the computational geometric method and least squares approximation that can be effective in monitor design. This paper provides insights into diagnostic monitoring of its effectiveness by attack simulations on a four-tank model and using computation techniques to diagnose it. Cyber security of instrumentation and control systems used in nuclear power plants is of paramount importance and hence could be a possible target of such applications.

  15. Interference statistics and capacity analysis for uplink transmission in two-tier small cell networks: A geometric probability approach

    KAUST Repository

    Tabassum, Hina

    2014-07-01

    This paper presents a novel framework to derive the statistics of the interference considering dedicated and shared spectrum access for uplink transmission in two-tier small cell networks such as the macrocell-femtocell networks. The framework exploits the distance distributions from geometric probability theory to characterize the uplink interference while considering a traditional grid-model set-up for macrocells along with the randomly deployed femtocells. The derived expressions capture the impact of path-loss, composite shadowing and fading, uniform and non-uniform traffic loads, spatial distribution of femtocells, and partial and full spectral reuse among femtocells. Considering dedicated spectrum access, first, we derive the statistics of co-tier interference incurred at both femtocell and macrocell base stations (BSs) from a single interferer by approximating generalized- K composite fading distribution with the tractable Gamma distribution. We then derive the distribution of the number of interferers considering partial spectral reuse and moment generating function (MGF) of the cumulative interference for both partial and full spectral reuse scenarios. Next, we derive the statistics of the cross-tier interference at both femtocell and macrocell BSs considering shared spectrum access. Finally, we utilize the derived expressions to analyze the capacity in both dedicated and shared spectrum access scenarios. The derived expressions are validated by the Monte Carlo simulations. Numerical results are generated to assess the feasibility of shared and dedicated spectrum access in femtocells under varying traffic load and spectral reuse scenarios. © 2014 IEEE.

  16. Morphometric analysis of the Marmara Sea river basins, Turkey

    Science.gov (United States)

    Elbaşı, Emre; Ozdemir, Hasan

    2014-05-01

    The drainage basin, the fundamental unit of the fluvial landscape, has been focus of research aimed at understanding the geometric characteristics of the master channel and its tributary network. This geometry is referred to as the basin morphometry and is nicely reviewed by Abrahams (1984). A great amount of research has focused on geometric characteristic of drainage basins, including the topology of the stream networks, and quantitative description of drainage texture, pattern, shape, and relief characteristics. Evaluation of morphometric parameters necessitates the analysis of various drainage parameters such as ordering of the various streams, measurement of basin area and perimeter, length of drainage channels, drainage density (Dd), stream frequency (Fs), bifurcation ratio (Rb), texture ratio (T), basin relief (Bh), Ruggedness number (Rn), time of concentration (Tc), hypsometric curve and integral (Hc and Hi) (Horton, 1932, Schumn, 1956, Strahler, 1957; Verstappen 1983; Keller and Pinter, 2002; Ozdemir and Bird, 2009). These morphometric parameters have generally been used to predict flood peaks, to assess sediment yield, and to estimate erosion rates in the basins. River basins of the Marmara Sea, has an area of approximately 40,000 sqkm, are the most important basins in Turkey based on their dense populations, industry and transportation systems. The primary aim of this study is to determine and analyse of morphometric characteristics of the Marmara Sea river basins using 10 m resolution Digital Elevation Model (DEM) and to evaluate of the results. For these purposes, digital 10 m contour maps scaled 1:25000 and geological maps scaled 1:100000 were used as the main data sources in the study. 10 m resolution DEM data were created using the contour maps and then drainage networks and their watersheds were extracted using D8 pour point model. Finally, linear, areal and relief morphometries were applied to the river basins using Geographic Information Systems

  17. Morphometric analysis of human embryos to predict developmental competence

    DEFF Research Database (Denmark)

    Ziebe, Søren

    2013-01-01

    , but rather choosing and prioritising between the available embryos. Data suggest that only approximately 5% of aspirated human oocytes have the competence to implant and develop into a child and that, in most treatment cycles, there is no oocyte capable of implanting. The most likely outcome is a negative......Morphometric and morphokinetic approaches toward embryo quality assessment have for many years been difficult due to technical limitations. Today, with improvements in laboratory techniques and subsequent quality, we have a better understanding of the morphometric and kinetics of embryo development....... Fertility clinics are moving from "sensing" embryo quality to measuring embryo quality--and this is happening every day in fertility clinics all over the world. However, we cannot select for something that is not there. In daily clinical life it is almost never a question of selecting the optimal embryo...

  18. Mobile Watermarking against Geometrical Distortions

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2015-08-01

    Full Text Available Mobile watermarking robust to geometrical distortions is still a great challenge. In mobile watermarking, efficient computation is necessary because mobile devices have very limited resources due to power consumption. In this paper, we propose a low-complexity geometrically resilient watermarking approach based on the optimal tradeoff circular harmonic function (OTCHF correlation filter and the minimum average correlation energy Mellin radial harmonic (MACE-MRH correlation filter. By the rotation, translation and scale tolerance properties of the two kinds of filter, the proposed watermark detector can be robust to geometrical attacks. The embedded watermark is weighted by a perceptual mask which matches very well with the properties of the human visual system. Before correlation, a whitening process is utilized to improve watermark detection reliability. Experimental results demonstrate that the proposed watermarking approach is computationally efficient and robust to geometrical distortions.

  19. Geometric phases in graphitic cones

    Energy Technology Data Exchange (ETDEWEB)

    Furtado, Claudio [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil)], E-mail: furtado@fisica.ufpb.br; Moraes, Fernando [Departamento de Fisica, CCEN, Universidade Federal da Paraiba, Cidade Universitaria, 58051-970 Joao Pessoa, PB (Brazil); Carvalho, A.M. de M [Departamento de Fisica, Universidade Estadual de Feira de Santana, BR116-Norte, Km 3, 44031-460 Feira de Santana, BA (Brazil)

    2008-08-04

    In this Letter we use a geometric approach to study geometric phases in graphitic cones. The spinor that describes the low energy states near the Fermi energy acquires a phase when transported around the apex of the cone, as found by a holonomy transformation. This topological result can be viewed as an analogue of the Aharonov-Bohm effect. The topological analysis is extended to a system with n cones, whose resulting configuration is described by an effective defect00.

  20. Geometric inequalities methods of proving

    CERN Document Server

    Sedrakyan, Hayk

    2017-01-01

    This unique collection of new and classical problems provides full coverage of geometric inequalities. Many of the 1,000 exercises are presented with detailed author-prepared-solutions, developing creativity and an arsenal of new approaches for solving mathematical problems. This book can serve teachers, high-school students, and mathematical competitors. It may also be used as supplemental reading, providing readers with new and classical methods for proving geometric inequalities. .

  1. Geometrical and P.D.E. Methods in the Treatment of the Theory of Shells: Comparing Euclidean and Affine Approaches

    Directory of Open Access Journals (Sweden)

    Salvador Gigena

    2014-01-01

    Full Text Available The use of differential equations methods in the approach, treatment, and solution of problems in diverse areas of geometry, particularly in affine differential geometry is well known and prolific, where they have proven to be quite fruitful when it comes to the obtainment of definite results. It is perhaps lesser known that the same kind of those very same methods has been and is currently being used to treat developments in some specific areas of applied sciences, such as the theory of shells where, similarly, they can be proven to be quite effective as well. In this paper we precisely show that such is the case in two particular, related instances: the historic approach of the classical, Euclidean part of the theory pursued by Fritz John, in the past century, and the more recent expositions that we ourselves have dedicated to the affine counterpart of the theory.

  2. Automation of Morphometric Measurements for Planetary Surface Analysis and Cartography

    Science.gov (United States)

    Kokhanov, A. A.; Bystrov, A. Y.; Kreslavsky, M. A.; Matveev, E. V.; Karachevtseva, I. P.

    2016-06-01

    For automation of measurements of morphometric parameters of surface relief various tools were developed and integrated into GIS. We have created a tool, which calculates statistical characteristics of the surface: interquartile range of heights, and slopes, as well as second derivatives of height fields as measures of topographic roughness. Other tools were created for morphological studies of craters. One of them allows automatic placing of topographic profiles through the geometric center of a crater. Another tool was developed for calculation of small crater depths and shape estimation, using C++ programming language. Additionally, we have prepared tool for calculating volumes of relief features from DTM rasters. The created software modules and models will be available in a new developed web-GIS system, operating in distributed cloud environment.

  3. AUTOMATION OF MORPHOMETRIC MEASUREMENTS FOR PLANETARY SURFACE ANALYSIS AND CARTOGRAPHY

    Directory of Open Access Journals (Sweden)

    A. A. Kokhanov

    2016-06-01

    Full Text Available For automation of measurements of morphometric parameters of surface relief various tools were developed and integrated into GIS. We have created a tool, which calculates statistical characteristics of the surface: interquartile range of heights, and slopes, as well as second derivatives of height fields as measures of topographic roughness. Other tools were created for morphological studies of craters. One of them allows automatic placing of topographic profiles through the geometric center of a crater. Another tool was developed for calculation of small crater depths and shape estimation, using C++ programming language. Additionally, we have prepared tool for calculating volumes of relief features from DTM rasters. The created software modules and models will be available in a new developed web-GIS system, operating in distributed cloud environment.

  4. Approaches to capture variance differences in rest fMRI networks in the spatial geometric features: Application to schizophrenia

    Directory of Open Access Journals (Sweden)

    Shruti eGopal

    2016-03-01

    Full Text Available Identification of functionally connected regions while at rest has been at the forefront of research focusing on understanding interactions between different brain regions. Studies have utilized a variety of approaches including seed based as well as data-driven approaches to identifying such networks. Most such techniques involve differentiating groups based on group mean measures. There has been little work focused on differences in spatial characteristics of resting fMRI data. We present a method to identify between group differences in the variability in the cluster characteristics of network regions within components estimated via independent vector analysis (IVA. IVA is a blind source separation approach shown to perform well in capturing individual subject variability within a group model. We evaluate performance of the approach using simulations and then apply to a relatively large schizophrenia data set (82 schizophrenia patients and 89 healthy controls. We postulate that group differences in the intra-network distributional characteristics of resting state network voxel intensities might indirectly capture important distinctions between the brain function of healthy and clinical populations. Results demonstrate that specific areas of the brain, superior and middle temporal gyrus that are involved in language and recognition of emotions, show greater component level variance in amplitude weights for schizophrenia patients than healthy controls. Statistically significant correlation between component level spatial variance and component volume was observed in 19 of the 27 non-artifactual components implying an evident relationship between the two parameters. Additionally, the greater spread in the distance of the cluster peak of a component from the centroid in schizophrenia patients compared to healthy controls was observed for seven components. These results indicate that there is hidden potential in exploring variance and possibly

  5. 黄斑蜂族的系统学研究:几何形态测量方法 (膜翅目:切叶蜂科)%Systematical studies on Anthidiini (Hymenoptera: Megachilidae):A geometric morphometric approach

    Institute of Scientific and Technical Information of China (English)

    Yasemin G(U)LER; A. Murat AYTEK(I)N; Ne(s)e (C)AGATAY

    2006-01-01

    利用采集于土耳其安纳托利亚中部(Middle Anatolia)的切叶蜂科6个种92头标本,选取虫体上的30个特征点(1andmarks)(其中前翅16个,后翅6个,头部8个),利用UPGMA等数值分类方法对不同属和种的亲缘关系进行了探讨.据此对一些种的归属和一些属的划分提出了一些与传统分类观点相同或不同的见解,但各种分析方法的结果都支持切叶蜂族Megachilini起源的单系性.%The classificatory schema in some groups of Megachilidae reorganized by means of shape differences in terms of the inter- and intra-specific and inter- and intra-generic and subgeneric deformations. The relative warps,UPGMA trees and PCA graphs obtained from 30 landmarks were shown. Both Anthidium cingulatum Latreille and A.florentinum (Fabricius) should better classify in the same subgenus Anthidium s. str. In the other case under the results of shape variation our results supported the hypothesis that Paraanthidium as a subgenus of Anthidium Fabricius. On the other hand Icteranthidium Michener and Paraanthidiellum Michener showed enough dissimilarity to be kept as separate genera. Our analysis also supported the monophyletic origin of Megachilini which was clustered as a separate group by all methods used.

  6. Automatic Actin Filament Quantification of Osteoblasts and Their Morphometric Analysis on Microtextured Silicon-Titanium Arrays

    Directory of Open Access Journals (Sweden)

    Claudia Matschegewski

    2012-06-01

    Full Text Available Microtexturing of implant surfaces is of major relevance in the endeavor to improve biorelevant implant designs. In order to elucidate the role of biomaterial’s topography on cell physiology, obtaining quantitative correlations between cellular behavior and distinct microarchitectural properties is in great demand. Until now, the microscopically observed reorganization of the cytoskeleton on structured biomaterials has been difficult to convert into data. We used geometrically microtextured silicon-titanium arrays as a model system. Samples were prepared by deep reactive-ion etching of silicon wafers, resulting in rectangular grooves (width and height: 2 µm and cubic pillars (pillar dimensions: 2 × 2 × 5 and 5 × 5 × 5 µm; finally sputter-coated with 100 nm titanium. We focused on the morphometric analysis of MG-63 osteoblasts, including a quantification of the actin cytoskeleton. By means of our novel software FilaQuant, especially developed for automatic actin filament recognition, we were first able to quantify the alterations of the actin network dependent on the microtexture of a material surface. The cells’ actin fibers were significantly reduced in length on the pillared surfaces versus the grooved array (4–5 fold and completely reorganized on the micropillars, but without altering the orientation of cells. Our morpho-functional approach opens new possibilities for the data correlation of cell-material interactions.

  7. Development of Virtual Morphometric Globes Using Blender

    CERN Document Server

    Florinsky, I V

    2015-01-01

    Virtual globes - programs implementing interactive three-dimensional (3D) models of planets - are increasingly used in geosciences. Global morphometric models can be useful for tectonic and planetary studies. We describe the development of the first testing version of the system of virtual morphometric globes for the Earth, Mars, and the Moon. As the initial data, we used three 15'-gridded global digital elevation models (DEMs) extracted from SRTM30_PLUS, the Mars Orbiter Laser Altimeter, and the Lunar Orbiter Laser Altimeter gridded archives. For three planetary bodies, we derived global digital models and maps of several morphometric attributes (i.e., horizontal curvature, vertical curvature, minimal curvature, maximal curvature, and catchment area). To develop the system, we used Blender, the open-source software for 3D modeling and visualization. First, a 3D sphere model was generated. Second, the global morphometric maps as textures were imposed to the sphere surface. Finally, the real-time 3D graphics B...

  8. Study on geometric approach of SVM algorithm SK algorithm analysis and study%SVM的几何方法——SK类思路的研究

    Institute of Scientific and Technical Information of China (English)

    常振华; 陈伯成; 李英杰; 刘文煌; 闫学为

    2011-01-01

    The geometric approach of the Support Vector Machine(SVM) is a kind of geometric way to find the solution to the problem of the SVM algorithm. Based on its geometric characters,the SK(Schlesinger-Kozinec) algorithm is studied intuitively. It briefly sums up the two convex hulls,based on their relative positions, into five categories,and makes sure their optimizing position got in each computing is mostly at the hull vertices or boundary,it can get to the boundary(the optimization place of the computing) at the first computation.The manual single-step simulation results show that the projection is not always successful for such kind of algorithms in many cases,though it can't affect the computing result,but can weaken the algorithm efficiency. Based on the analysis,it demonstrates two improving ways for the soft SK algorithm(Backward-SK and Forward-SK methods),and makes some simulation for comparing. The simulation results show that the improved method computing results are almost same as the SK and soft SK ones,but the computing process of improved one is more intuitive.%支持向量机(Support Vector Machine,SVM)的几何方法是一种基于SVM计算过程中几何意义出发的求解方法.利用其几何特点,比较直观地对其基本算法的构建过程进行了分析.两凸包相对位置可以简要地归纳成5类,且在该类算法迭代过程最优点多在顶点和边界上,该类算法在第一次迭代就可能达到边界(最优点);该类算法的手动单步模拟计结果揭示:很多情况下,该类算法迭代过程的投影并不成功,虽不影响解法的最终结果,但会影响迭代效率:基于几何的分析,给出软SK软算法的两种改进思路(Backward-SK和Forward-SK思路),并进行了仿真比较计算.实验表明,该方法计算效果与原思路相似,但是计算过程理解更加直观.

  9. Analysis of accuracy in pointing with redundant hand-held tools: a geometric approach to the uncontrolled manifold method.

    Science.gov (United States)

    Campolo, Domenico; Widjaja, Ferdinan; Xu, Hong; Ang, Wei Tech; Burdet, Etienne

    2013-04-01

    This work introduces a coordinate-independent method to analyse movement variability of tasks performed with hand-held tools, such as a pen or a surgical scalpel. We extend the classical uncontrolled manifold (UCM) approach by exploiting the geometry of rigid body motions, used to describe tool configurations. In particular, we analyse variability during a static pointing task with a hand-held tool, where subjects are asked to keep the tool tip in steady contact with another object. In this case the tool is redundant with respect to the task, as subjects control position/orientation of the tool, i.e. 6 degrees-of-freedom (dof), to maintain the tool tip position (3dof) steady. To test the new method, subjects performed a pointing task with and without arm support. The additional dof introduced in the unsupported condition, injecting more variability into the system, represented a resource to minimise variability in the task space via coordinated motion. The results show that all of the seven subjects channeled more variability along directions not directly affecting the task (UCM), consistent with previous literature but now shown in a coordinate-independent way. Variability in the unsupported condition was only slightly larger at the endpoint but much larger in the UCM.

  10. DNA immunisation. New histochemical and morphometric data

    Directory of Open Access Journals (Sweden)

    D Ehirchiou

    2010-01-01

    Full Text Available Splenic germinal center reactions were measured during primary response to a plasmidic DNA intramuscular injection. Cardiotoxin-pretreated Balb/c mice were immunized with DNA plasmids encoding or not the SAG1 protein, a membrane antigen of Toxoplasma gondii. Specific anti-SAG1 antibodies were detected on days 16 and 36 after injection of coding plasmids. The results of ELISAs showed that the SAG1-specific antibodies are of the IgG2a class. Morphometric analyses were done on serial immunostained cryosections of spleen and draining or non-draining lymph nodes. This new approach made it possible to evaluate the chronological changes induced by DNA immunisation in the germinal centres (in number and in size. Significant increases in the number of germinal centres were measured in the spleen and only in draining lymph nodes after plasmid injection. the measured changes of the germinal centers appeared to result from the adjuvant stimulatory effect of the plasmidic DNA since both the coding and the noncoding plasmid DNA induced them. No measurable changes were recorded in the Tdependent zone of lymph organs.

  11. Geometric constraint solving with geometric transformation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper proposes two algorithms for solving geometric constraint systems. The first algorithm is for constrained systems without loops and has linear complexity. The second algorithm can solve constraint systems with loops. The latter algorithm is of quadratic complexity and is complete for constraint problems about simple polygons. The key to it is to combine the idea of graph based methods for geometric constraint solving and geometric transformations coming from rule-based methods.

  12. A morphometric and molecular study of Anastrepha pickeli Lima (Diptera: Tephritidae).

    Science.gov (United States)

    Bomfim, Z V; Lima, K M; Silva, J G; Costa, M A; Zucchi, Robert A

    2011-10-01

    This study investigated the level of morphometric and genetic variability among populations of Anastrepha pickeli Lima from several localities in Brazil, one locality in Bolivia and one in Paraguay. Traditional and geometric morphometric analyses were used, as well as sequencing of a fragment of the cytochrome oxidase gene (COI). Six variables were measured from the aculeus for traditional morphometric analysis and 14 landmarks from the right wing were used for geometric analysis, using 10 specimes/population. The aculeus tip length, aculeus width at the end of the cloaca opening, and the serrate part length contributed with 62.7% for grouping. According to the results from traditional morphometry, there was no significant difference, but the multivariate tests showed that the canonical variables were statistically significant, indicating a difference in the wing conformation among populations. Molecular phylogenetic analysis indicated that the populations clustered into three clades and revealed a high level of genetic variation within A. pickeli populations from various geographic regions. Anastrepha pickeli populations differed among them according to the methods used in this study, showing incongruence among the methods used.

  13. Geometric Design Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The mission of the Geometric Design Laboratory (GDL) is to support the Office of Safety Research and Development in research related to the geometric design...

  14. On Geometric Infinite Divisibility

    OpenAIRE

    Sandhya, E.; Pillai, R. N.

    2014-01-01

    The notion of geometric version of an infinitely divisible law is introduced. Concepts parallel to attraction and partial attraction are developed and studied in the setup of geometric summing of random variables.

  15. Bidimensionality and Geometric Graphs

    CERN Document Server

    Fomin, Fedor V; Saurabh, Saket

    2011-01-01

    In this paper we use several of the key ideas from Bidimensionality to give a new generic approach to design EPTASs and subexponential time parameterized algorithms for problems on classes of graphs which are not minor closed, but instead exhibit a geometric structure. In particular we present EPTASs and subexponential time parameterized algorithms for Feedback Vertex Set, Vertex Cover, Connected Vertex Cover, Diamond Hitting Set, on map graphs and unit disk graphs, and for Cycle Packing and Minimum-Vertex Feedback Edge Set on unit disk graphs. Our results are based on the recent decomposition theorems proved by Fomin et al [SODA 2011], and our algorithms work directly on the input graph. Thus it is not necessary to compute the geometric representations of the input graph. To the best of our knowledge, these results are previously unknown, with the exception of the EPTAS and a subexponential time parameterized algorithm on unit disk graphs for Vertex Cover, which were obtained by Marx [ESA 2005] and Alber and...

  16. A global distributed basin morphometric dataset

    Science.gov (United States)

    Shen, Xinyi; Anagnostou, Emmanouil N.; Mei, Yiwen; Hong, Yang

    2017-01-01

    Basin morphometry is vital information for relating storms to hydrologic hazards, such as landslides and floods. In this paper we present the first comprehensive global dataset of distributed basin morphometry at 30 arc seconds resolution. The dataset includes nine prime morphometric variables; in addition we present formulas for generating twenty-one additional morphometric variables based on combination of the prime variables. The dataset can aid different applications including studies of land-atmosphere interaction, and modelling of floods and droughts for sustainable water management. The validity of the dataset has been consolidated by successfully repeating the Hack's law.

  17. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

    Andersen, Vedrana; Desbrun, Mathieu; Bærentzen, Jakob Andreas

    2009-01-01

    We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... compromise between functionality and simplicity: it can efficiently handle and process geometric texture too complex to be represented as a height field, without having recourse to full blown mesh editing algorithms. The height-and-tilt representation proposed here is fully intrinsic to the mesh, making...

  18. Asymptotic geometric analysis, part I

    CERN Document Server

    Artstein-Avidan, Shiri

    2015-01-01

    The authors present the theory of asymptotic geometric analysis, a field which lies on the border between geometry and functional analysis. In this field, isometric problems that are typical for geometry in low dimensions are substituted by an "isomorphic" point of view, and an asymptotic approach (as dimension tends to infinity) is introduced. Geometry and analysis meet here in a non-trivial way. Basic examples of geometric inequalities in isomorphic form which are encountered in the book are the "isomorphic isoperimetric inequalities" which led to the discovery of the "concentration phenomen

  19. Geometric Computing Based on Computerized Descriptive Geometric

    Institute of Scientific and Technical Information of China (English)

    YU Hai-yan; HE Yuan-Jun

    2011-01-01

    Computer-aided Design (CAD), video games and other computer graphic related technology evolves substantial processing to geometric elements. A novel geometric computing method is proposed with the integration of descriptive geometry, math and computer algorithm. Firstly, geometric elements in general position are transformed to a special position in new coordinate system. Then a 3D problem is projected to new coordinate planes. Finally, according to 2D/3D correspondence principle in descriptive geometry, the solution is constructed computerized drawing process with ruler and compasses. In order to make this method a regular operation, a two-level pattern is established. Basic Layer is a set algebraic packaged function including about ten Primary Geometric Functions (PGF) and one projection transformation. In Application Layer, a proper coordinate is established and a sequence of PGFs is sought for to get the final results. Examples illustrate the advantages of our method on dimension reduction, regulatory and visual computing and robustness.

  20. Molecular and morphometric variation in chromosomally differentiated populations of the grasshopper Sinipta dalmani (Orthopthera: Acrididae).

    Science.gov (United States)

    Sesarini, Carla; Remis, Maria I

    2008-07-01

    Sinipta dalmani is an Argentine grasshopper whose chromosome polymorphisms have been widely studied through cytogenetic, morphometric, and fitness component analyses. The present work analysed molecular and morphometric variation in seven chromosomally differentiated populations from Entre Rios and Buenos Aires provinces to analyse population structure. Molecular studies were performed studying RAPD loci and morphometric analyses were carried out measuring five morphometric traits. Genetic variability was high in all studied populations and was characterized by a decrease in H as a function of latitude and temperature. Both conventional F(ST) analysis and Bayesian approach for dominant marker showed that there were significant genetic differences among all populations, between provinces, and among populations within provinces. Entre Rios populations showed higher mean numbers of migrants per generation as well as low genetic differentiation and high gene flow with almost all populations whereas Buenos Aires populations may be considered as a result of a more recently colonization. There is considerable morphometric variation between populations and this variation correlates with latitude and temperature. Our results suggest that selection contributes to phenotypic differentiation among populations by moulding the differences in trait means whereas genetic drift is responsible for differences in the matrix of variance-covariance. The gene flow detected is insufficient to prevent phenotypic and chromosome divergences.

  1. Geometrical splitting and reduction of Feynman diagrams

    Science.gov (United States)

    Davydychev, Andrei I.

    2016-10-01

    A geometrical approach to the calculation of N-point Feynman diagrams is reviewed. It is shown that the geometrical splitting yields useful connections between Feynman integrals with different momenta and masses. It is demonstrated how these results can be used to reduce the number of variables in the occurring functions.

  2. The geometric semantics of algebraic quantum mechanics.

    Science.gov (United States)

    Cruz Morales, John Alexander; Zilber, Boris

    2015-08-06

    In this paper, we will present an ongoing project that aims to use model theory as a suitable mathematical setting for studying the formalism of quantum mechanics. We argue that this approach provides a geometric semantics for such a formalism by means of establishing a (non-commutative) duality between certain algebraic and geometric objects.

  3. Morphometric Characterization of Small Cell Lymphocytic Lymphoma

    Directory of Open Access Journals (Sweden)

    Chisoi Anca

    2014-11-01

    Full Text Available The morphometry in histopathology is used to characterize cell populations belonging to different tissues and to identify differences in their parameters with prognostic implications. To achieve morphometric examination were selected 6 of 24 cases identified as small cell lymphocytic lymphoma. For each case analysis was done on five fields, for each field measuring the parameters of 20 cells. The studied parameters were for cytoplasm: cytoplasmic area, maximum and minimum cytoplasmic diameter, cytoplasmic perimeter; for nucleus were measured: nuclear area, minimum and maximum nuclear diameter, nuclear perimeter, nuclear contour index, nuclear ellipticity index, nuclear irregularity index. Also the nucleocytoplasmic ratio was calculated in all studied cases. Small cell lymphocytic lymphoma is characterized in morphometric terms having a small cytoplasmic area (average 29.206 and also a small nuclear area (mean 28.939 having a nucleo-cytoplasmic ratio appearance suggestive for adult lymphocyte. A nuclear contour index small value (3.946, ellipticity index value also small (3.521 and small nuclear irregularity index (3.965. Standard deviations, in any of the studied morphometric categories, is around or below 1 suggesting monomorphic cell appearance. These morphometric and microscopic features characterized mainly by a small population of adult lymphocytes, monomorphic, with rounded hipercromic nuclei, dense chromatin, support the framing into indolent lymphoma group in terms of clinical outcome.

  4. Morphometric study of Euchiton (Gnaphalieae: Asteraceae)

    NARCIS (Netherlands)

    Flann, C.M.

    2010-01-01

    A morphometric study was undertaken to survey taxa in the genus Euchiton Cass., distributed across Australia, New Zealand and South-east Asia. Phenetic analyses of herbarium specimens showed several taxa to be well delimited, including E. brassii (Mattf.) Anderb., E. breviscapus (Mattf.) Anderb., E.

  5. Morphometric study of Euchiton (Gnaphalieae: Asteraceae)

    NARCIS (Netherlands)

    Flann, C.M.

    2010-01-01

    A morphometric study was undertaken to survey taxa in the genus Euchiton Cass., distributed across Australia, New Zealand and South-east Asia. Phenetic analyses of herbarium specimens showed several taxa to be well delimited, including E. brassii (Mattf.) Anderb., E. breviscapus (Mattf.) Anderb., E.

  6. A Kalman filter-based approach to reduce the effects of geometric errors and the measurement noise in the inverse ECG problem.

    Science.gov (United States)

    Aydin, Umit; Dogrusoz, Yesim Serinagaoglu

    2011-09-01

    In this article, we aimed to reduce the effects of geometric errors and measurement noise on the inverse problem of Electrocardiography (ECG) solutions. We used the Kalman filter to solve the inverse problem in terms of epicardial potential distributions. The geometric errors were introduced into the problem via wrong determination of the size and location of the heart in simulations. An error model, which is called the enhanced error model (EEM), was modified to be used in inverse problem of ECG to compensate for the geometric errors. In this model, the geometric errors are modeled as additive Gaussian noise and their noise variance is added to the measurement noise variance. The Kalman filter method includes a process noise component, whose variance should also be estimated along with the measurement noise. To estimate these two noise variances, two different algorithms were used: (1) an algorithm based on residuals, (2) expectation maximization algorithm. The results showed that it is important to use the correct noise variances to obtain accurate results. The geometric errors, if ignored in the inverse solution procedure, yielded incorrect epicardial potential distributions. However, even with a noise model as simple as the EEM, the solutions could be significantly improved.

  7. Morphometric Assessment of Convergent Tool Technology and Function during the Early Middle Palaeolithic: The Case of Payre, France.

    Directory of Open Access Journals (Sweden)

    M Gema Chacón

    Full Text Available There appears to be little doubt as to the existence of an intentional technological resolve to produce convergent tools during the Middle Palaeolithic. However, the use of these pieces as pointed tools is still subject to debate: i.e., handheld tool vs. hafted tool. Present-day technological analysis has begun to apply new methodologies in order to quantify shape variability and to decipher the role of the morphology of these pieces in relation to function; for instance, geometric morphometric analyses have recently been applied with successful results. This paper presents a study of this type of analysis on 37 convergent tools from level Ga of Payre site (France, dated to MIS 8-7. These pieces are non-standardized knapping products produced by discoidal and orthogonal core technologies. Moreover, macro-wear studies attest to various activities on diverse materials with no evidence of hafting or projectile use. The aim of this paper is to test the geometric morphometric approach on non-standardized artefacts applying the Elliptical Fourier analysis (EFA to 3D contours and to assess the potential relationship between size and shape, technology and function. This study is innovative in that it is the first time that this method, considered to be a valuable complement for describing technological and functional attributes, is applied to 3D contours of lithic products. Our results show that this methodology ensures a very good degree of accuracy in describing shape variations of the sharp edges of technologically non-standardized convergent tools. EFA on 3D contours indicates variations in deviations of the outline along the third dimension (i.e., dorso-ventrally and yields quantitative and insightful information on the actual shape variations of tools. Several statistically significant relationships are found between shape variation and use-wear attributes, though the results emphasize the large variability of the shape of the convergent tools

  8. Morphometric characteristics of bacteroidal tissue in yellow lupine (Lupinus luteus L. nodules

    Directory of Open Access Journals (Sweden)

    Władysław Golinowski

    2014-01-01

    Full Text Available Morphometric methods were used to analyse the bacteroidal tissue in yellow lupine nodules. Volume fraction - Vv, surface area - Sv and ratio of surface area to its volume - R, were calculated from electron micrographs for some selected cell structures in 9, 13, 15, 20, 29 and 60 day-old nodules. The rate at which bacteroid Vv increased varied in time. Between days 13 and 20 of nodule development, bacteroid Vv increased in geometrical progression. Rough endoplasmic reticulum was active in nodule development and/or protein manufacturing necessary for the functioning of the system whereas the role of mitochondria was apparently limited.

  9. The relationship between morphometric parameters and Trendelenburg sign following the Hardinge incision

    OpenAIRE

    Bulbul, Murat; Ayanoglu, Semih; Beytemur, Ozan; Gurkan, Volkan; Esenyel, Cem Zeki; Gurbuz, Hakan

    2004-01-01

    Objectives: We evaluated the relationship between morphometric parameters such as height, weight, and body mass index with the development of the Trendelenburg gait following the Hardinge approach, which is one of the most commonly used approaches in total hip arthroplasty. Methods: The study included 59 patients (43 women, 16 men; mean age 55 years; range 37 to 74 years) who underwent total hip arthroplasty via the Hardinge approach for primary coxarthrosis. The patients were examined pos...

  10. Geometrization of Trace Formulas

    CERN Document Server

    Frenkel, Edward

    2010-01-01

    Following our joint work arXiv:1003.4578 with Robert Langlands, we make the first steps toward developing geometric methods for analyzing trace formulas in the case of the function field of a curve defined over a finite field. We also suggest a conjectural framework of geometric trace formulas for curves defined over the complex field, which exploits the categorical version of the geometric Langlands correspondence.

  11. Localized Geometric Query Problems

    CERN Document Server

    Augustine, John; Maheshwari, Anil; Nandy, Subhas C; Roy, Sasanka; Sarvattomananda, Swami

    2011-01-01

    A new class of geometric query problems are studied in this paper. We are required to preprocess a set of geometric objects $P$ in the plane, so that for any arbitrary query point $q$, the largest circle that contains $q$ but does not contain any member of $P$, can be reported efficiently. The geometric sets that we consider are point sets and boundaries of simple polygons.

  12. A physics perspective on geometric Langlands duality

    CERN Document Server

    Schlesinger, Karl-Georg

    2009-01-01

    We review the approach to the geometric Langlands program for algebraic curves via S-duality of an N=4 supersymmetric four dimensional gauge theory, initiated by Kapustin and Witten in 2006. We sketch some of the central further developments. Placing this four dimensional gauge theory into a six dimensional framework, as advocated by Witten, holds the promise to lead to a formulation which makes geometric Langlands duality a manifest symmetry (like coavariance in differential geometry). Furthermore, it leads to an approach toward geometric Langlands duality for algebraic surfaces, reproducing and extending the recent results of Braverman and Finkelberg.

  13. Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae).

    Science.gov (United States)

    Paris, Thomson M; Allan, Sandra A; Hall, David G; Hentz, Matthew G; Hetesy, Gabriella; Stansly, Philip A

    2016-01-01

    The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

  14. Host plant affects morphometric variation of Diaphorina citri (Hemiptera: Liviidae

    Directory of Open Access Journals (Sweden)

    Thomson M. Paris

    2016-11-01

    Full Text Available The Asian citrus psyllid (ACP, Diaphorina citri Kuwayama, is one of the most serious citrus pests worldwide due to its role as vector of huanglongbing or citrus greening disease. While some optimal plant species for ACP oviposition and development have been identified, little is known of the influence of host plants on ACP size and shape. Our goal was to determine how size and shape of ACP wing and body size varies when development occurs on different host plants in a controlled rearing environment. ACP were reared on six different rutaceous species; Bergera koenigii, Citrus aurantifolia, Citrus macrophylla, Citrus maxima, Citrus taiwanica and Murraya paniculata. Adults were examined for morphometric variation using traditional and geometric analysis based on 12 traits or landmarks. ACP reared on C. taiwanica were consistently smaller than those reared on the other plant species. Wing aspect ratio also differed between C. maxima and C. taiwanica. Significant differences in shape were detected with those reared on M. paniculata having narrower wings than those reared on C. macrophylla. This study provides evidence of wing size and shape differences of ACP based on host plant species which potentially may impact dispersal. Further study is needed to determine if behavioral and physiological differences are associated with the observed phenotypic differences.

  15. Exploring New Geometric Worlds

    Science.gov (United States)

    Nirode, Wayne

    2015-01-01

    When students work with a non-Euclidean distance formula, geometric objects such as circles and segment bisectors can look very different from their Euclidean counterparts. Students and even teachers can experience the thrill of creative discovery when investigating these differences among geometric worlds. In this article, the author describes a…

  16. Geometric hashing and object recognition

    Science.gov (United States)

    Stiller, Peter F.; Huber, Birkett

    1999-09-01

    We discuss a new geometric hashing method for searching large databases of 2D images (or 3D objects) to match a query built from geometric information presented by a single 3D object (or single 2D image). The goal is to rapidly determine a small subset of the images that potentially contain a view of the given object (or a small set of objects that potentially match the item in the image). Since this must be accomplished independent of the pose of the object, the objects and images, which are characterized by configurations of geometric features such as points, lines and/or conics, must be treated using a viewpoint invariant formulation. We are therefore forced to characterize these configurations in terms of their 3D and 2D geometric invariants. The crucial relationship between the 3D geometry and its 'residual' in 2D is expressible as a correspondence (in the sense of algebraic geometry). Computing a set of generating equations for the ideal of this correspondence gives a complete characterization of the view of independent relationships between an object and all of its possible images. Once a set of generators is in hand, it can be used to devise efficient recognition algorithms and to give an efficient geometric hashing scheme. This requires exploiting the form and symmetry of the equations. The result is a multidimensional access scheme whose efficiency we examine. Several potential directions for improving this scheme are also discussed. Finally, in a brief appendix, we discuss an alternative approach to invariants for generalized perspective that replaces the standard invariants by a subvariety of a Grassmannian. The advantage of this is that one can circumvent many annoying general position assumptions and arrive at invariant equations (in the Plucker coordinates) that are more numerically robust in applications.

  17. Geometric and unipotent crystals

    OpenAIRE

    Berenstein, Arkady; Kazhdan, David

    1999-01-01

    In this paper we introduce geometric crystals and unipotent crystals which are algebro-geometric analogues of Kashiwara's crystal bases. Given a reductive group G, let I be the set of vertices of the Dynkin diagram of G and T be the maximal torus of G. The structure of a geometric G-crystal on an algebraic variety X consists of a rational morphism \\gamma:X-->T and a compatible family e_i:G_m\\times X-->X, i\\in I of rational actions of the multiplicative group G_m satisfying certain braid-like ...

  18. A multidisciplinary approach to identify pelagic shark fins by molecular, morphometric and digital correlation data Enfoque multidisciplinario para la identificación de aletas de tiburones pelágicos con datos moleculares, morfométricos y análisis digitales

    Directory of Open Access Journals (Sweden)

    Sebastián Hernández

    2010-04-01

    Full Text Available Accurate species identification is one of the most important issues to conserve and manage shark fisheries. A multidisciplinary approach involving molecular (using variation at ITS2 sequences, morphometrical and image processing species identification was performed to evaluate their discriminating power with three pelagic shark species common to the coasts of Chile (Prionace glauca Linnaeus 1785, Isurus oxyrinchus Rafinesque 1810, and Lamna nasus (Bonnaterre, 1788. Species-specific DNA markers and multivariate analyses based on twenty morphometrical measurements were used to identify fresh and dry fin sets for each shark species. Additionally, coloring patterns and fin shape were jointly used to distinguish dry fin sets of shark species by using digital invariant correlation (relation target and problem image independent of their changes in position, scale and rotation. Our results showed that morphometrical analysis was the least accurate approach, whereas DNA-based identification and image processing approaches were 100% successful on the identification of shark species. Thus ITS2 sequences and morphological diagnostic characteristics such as the ones related to color patterns, allow the correct identification of shark species. Therefore, the implementation of molecular and/or image tools can be applied to confidently identify the main pelagic shark species involved in Chilean landing and fin trade.La identificación correcta de las especies es uno de los más importantes temas para la conservación y el manejo de las pesquerías de tiburones. Un análisis multidisciplinario que involucra el procesamiento de datos moleculares, morfométricos e imágenes fue realizado para evaluar su capacidad de discriminación de tres especies de tiburones pelágicos comunes en las costas de Chile (Prionace glauca Linnaeus 1758, Isurus oxyrinchus Rafinesque 1810, and Lamna nasus Bonnaterre, 1788. Marcadores moleculares especie-específicos y an

  19. Geometrical Phases in Quantum Mechanics

    Science.gov (United States)

    Christian, Joy Julius

    In quantum mechanics, the path-dependent geometrical phase associated with a physical system, over and above the familiar dynamical phase, was initially discovered in the context of adiabatically changing environments. Subsequently, Aharonov and Anandan liberated this phase from the original formulation of Berry, which used Hamiltonians, dependent on curves in a classical parameter space, to represent the cyclic variations of the environments. Their purely quantum mechanical treatment, independent of Hamiltonians, instead used the non-trivial topological structure of the projective space of one-dimensional subspaces of an appropriate Hilbert space. The geometrical phase, in their treatment, results from a parallel transport of the time-dependent pure quantum states along a curve in this space, which is endowed with an abelian connection. Unlike Berry, they were able to achieve this without resort to an adiabatic approximation or to a time-independent eigenvalue equation. Prima facie, these two approaches are conceptually quite different. After a review of both approaches, an exposition bridging this apparent conceptual gap is given; by rigorously analyzing a model composite system, it is shown that, in an appropriate correspondence limit, the Berry phase can be recovered as a special case from the Aharonov-Anandan phase. Moreover, the model composite system is used to show that Berry's correction to the traditional Born-Oppenheimer energy spectra indeed brings the spectra closer to the exact results. Then, an experimental arrangement to measure geometrical phases associated with cyclic and non-cyclic variations of quantum states of an entangled composite system is proposed, utilizing the fundamental ideas of the recently opened field of two-particle interferometry. This arrangement not only resolves the controversy regarding the true nature of the phases associated with photon states, but also unequivocally predicts experimentally accessible geometrical phases in a

  20. Guiding light via geometric phases

    CERN Document Server

    Slussarenko, Sergei; Jisha, Chandroth P; Piccirillo, Bruno; Santamato, Enrico; Assanto, Gaetano; Marrucci, Lorenzo

    2015-01-01

    Known methods for transverse confinement and guidance of light can be grouped into a few basic mechanisms, the most common being metallic reflection, total internal reflection and photonic-bandgap (or Bragg) reflection. All of them essentially rely on changes of the refractive index, that is on scalar properties of light. Recently, processes based on "geometric Berry phases", such as manipulation of polarization states or deflection of spinning-light rays, have attracted considerable interest in the contexts of singular optics and structured light. Here, we disclose a new approach to light waveguiding, using geometric Berry phases and exploiting polarization states and their handling. This can be realized in structured three-dimensional anisotropic media, in which the optic axis lies orthogonal to the propagation direction and is modulated along it and across the transverse plane, so that the refractive index remains constant but a phase distortion can be imposed on a beam. In addition to a complete theoretic...

  1. Geometric and engineering drawing

    CERN Document Server

    Morling, K

    2010-01-01

    The new edition of this successful text describes all the geometric instructions and engineering drawing information that are likely to be needed by anyone preparing or interpreting drawings or designs with plenty of exercises to practice these principles.

  2. Differential geometric structures

    CERN Document Server

    Poor, Walter A

    2007-01-01

    This introductory text defines geometric structure by specifying parallel transport in an appropriate fiber bundle and focusing on simplest cases of linear parallel transport in a vector bundle. 1981 edition.

  3. Guessing Geometric Shapes.

    Science.gov (United States)

    Bledsoe, Gloria J

    1987-01-01

    The game of "Guess What" is described as a stimulating vehicle for students to consider the unifying or distinguishing features of geometric figures. Teaching suggestions as well as the gameboard are provided. (MNS)

  4. Geometric continuum mechanics and induced beam theories

    CERN Document Server

    R Eugster, Simon

    2015-01-01

    This research monograph discusses novel approaches to geometric continuum mechanics and introduces beams as constraint continuous bodies. In the coordinate free and metric independent geometric formulation of continuum mechanics as well as for beam theories, the principle of virtual work serves as the fundamental principle of mechanics. Based on the perception of analytical mechanics that forces of a mechanical system are defined as dual quantities to the kinematical description, the virtual work approach is a systematic way to treat arbitrary mechanical systems. Whereas this methodology is very convenient to formulate induced beam theories, it is essential in geometric continuum mechanics when the assumptions on the physical space are relaxed and the space is modeled as a smooth manifold. The book addresses researcher and graduate students in engineering and mathematics interested in recent developments of a geometric formulation of continuum mechanics and a hierarchical development of induced beam theories.

  5. Saturation and geometrical scaling

    CERN Document Server

    Praszalowicz, Michal

    2016-01-01

    We discuss emergence of geometrical scaling as a consequence of the nonlinear evolution equations of QCD, which generate a new dynamical scale, known as the saturation momentum: Qs. In the kinematical region where no other energy scales exist, particle spectra exhibit geometrical scaling (GS), i.e. they depend on the ratio pT=Qs, and the energy dependence enters solely through the energy dependence of the saturation momentum. We confront the hypothesis of GS in different systems with experimental data.

  6. STUDY OF MORPHOMETRIC CHANGES OF FOETAL STOMACH

    Directory of Open Access Journals (Sweden)

    Mohammed Aneesur Rahman

    2017-07-01

    Full Text Available BACKGROUND Interest in human development is very widespread largely because of the curiosity about our beginnings and desire to improve the quality of life. Understanding of the processes involved in the formation of various organs and systems has unrevealed most cryptic secrets of the nature. Human development begins at fertilisation when a male gamete or sperm unites with a female gamete or oocyte to form a single cell, a zygote. With the formation of zygote (single-celled stage, foetal development begins. The aim of the study is to- 1 Study the morphometric parameters of foetal stomach at various gestational ages. 2 Compare these observations with the previous studies. MATERIALS AND METHODS Present work was the cross-sectional study carried out in the Department of Anatomy in collaboration with the Department of Obstetrics and Gynaecology at SRTRGMC and Hospital, Ambajogai Dist., Beed, Maharashtra. For this, approval of Institutional Ethical Committee was taken. 30 aborted human foetuses of different age groups ranging from 12 to 36 weeks of fertilisation were taken from the Department of OB-GYN. Foetuses were preserved by using 10% formalin. Age of foetuses were determined by crown-rump length and history given by mother. Foetuses were dissected after preservation for 15 days and morphometric studies were done on stomach. RESULTS Various quantitative parameters like weight of foetus, crown-rump length, total length of stomach, weight of stomach, length of greater curvature, lesser curvature, width of cardia and width of pylorus were used. For the purpose of study and comparison with other researchers, the foetuses were divided into 3 groups. Morphometric changes were observed in different groups and compared with previous studies. CONCLUSION With the increase in the body weight, crown-rump length and gestational age of the foetus, there is gradual increase on various parameters of stomach.

  7. A common geometric data-base approach for computer-aided manufacturing of wind-tunnel models and theoretical aerodynamic analysis

    Science.gov (United States)

    See, M. J.; Cozzolongo, J. V.

    1983-01-01

    A more automated process to produce wind tunnel models using existing facilities is discussed. A process was sought to more rapidly determine the aerodynamic characteristics of advanced aircraft configurations. Such aerodynamic characteristics are determined from theoretical analyses and wind tunnel tests of the configurations. Computers are used to perform the theoretical analyses, and a computer aided manufacturing system is used to fabricate the wind tunnel models. In the past a separate set of input data describing the aircraft geometry had to be generated for each process. This process establishes a common data base by enabling the computer aided manufacturing system to use, via a software interface, the geometric input data generated for the theoretical analysis. Thus, only one set of geometric data needs to be generated. Tests reveal that the process can reduce by several weeks the time needed to produce a wind tunnel model component. In addition, this process increases the similarity of the wind tunnel model to the mathematical model used by the theoretical aerodynamic analysis programs. Specifically, the wind tunnel model can be machined to within 0.008 in. of the original mathematical model. However, the software interface is highly complex and cumbersome to operate, making it unsuitable for routine use. The procurement of an independent computer aided design/computer aided manufacturing system with the capability to support both the theoretical analysis and the manufacturing tasks was recommended.

  8. Analysis of Hyoid-Larynx Complex Using 3D Geometric Morphometrics.

    Science.gov (United States)

    Loth, Anthony; Corny, Julien; Santini, Laure; Dahan, Laurie; Dessi, Patrick; Adalian, Pascal; Fakhry, Nicolas

    2015-06-01

    The aim of this study was to obtain a quantitative anatomical description of the hyoid bone-larynx complex using modern 3D reconstruction tools. The study was conducted on 104 bones from CT scan images of living adult subjects. Three-dimensional reconstructions were created from CT scan images using AVIZO 6.2 software package. A study of this complex was carried out using metric and morphological analyses. Characteristics of the hyoid bone and larynx were highly heterogeneous and were closely linked with the sex, height, and weight of the individuals. Height and width of larynx were significantly greater in men than in women (24.99 vs. 17.3 mm, p ≤ 0.05 and 46.75 vs. 41.07, p ≤ 0.05), whereas the thyroid angle was larger in females (81.12° vs. 74.48°, p ≤ 0.05). There was a significant correlation between the height and weight of subjects and different measurements of the hyoid-larynx complex. (Pearson's coefficient correlation r = 0.42, p ≤ 0.05 between the height of thyroid ala and the height of subjects and r = 0.1, p ≤ 0.05 between the height of thyroid ala and the weight of subjects). Shape and size analysis of the hyoid-larynx complex showed the existence of a significant sexual dimorphism and high interindividual heterogeneity depending to patient morphology. These results encourage us to go further with functional and imaging correlations.

  9. Polar metals by geometric design

    Science.gov (United States)

    Kim, T. H.; Puggioni, D.; Yuan, Y.; Xie, L.; Zhou, H.; Campbell, N.; Ryan, P. J.; Choi, Y.; Kim, J.-W.; Patzner, J. R.; Ryu, S.; Podkaminer, J. P.; Irwin, J.; Ma, Y.; Fennie, C. J.; Rzchowski, M. S.; Pan, X. Q.; Gopalan, V.; Rondinelli, J. M.; Eom, C. B.

    2016-05-01

    Gauss’s law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions. Quantum physics supports this view, demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals—it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases. Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO3 perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements. We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra—the structural signatures of perovskites—owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported, non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.

  10. Geometric systematic prostate biopsy.

    Science.gov (United States)

    Chang, Doyoung; Chong, Xue; Kim, Chunwoo; Jun, Changhan; Petrisor, Doru; Han, Misop; Stoianovici, Dan

    2017-04-01

    The common sextant prostate biopsy schema lacks a three-dimensional (3D) geometric definition. The study objective was to determine the influence of the geometric distribution of the cores on the detection probability of prostate cancer (PCa). The detection probability of significant (>0.5 cm(3)) and insignificant (geometric distribution of the cores was optimized to maximize the probability of detecting significant cancer for various prostate sizes (20-100cm(3)), number of biopsy cores (6-40 cores) and biopsy core lengths (14-40 mm) for transrectal and transperineal biopsies. The detection of significant cancer can be improved by geometric optimization. With the current sextant biopsy, up to 20% of tumors may be missed at biopsy in a 20 cm(3) prostate due to the schema. Higher number and longer biopsy cores are required to sample with an equal detection probability in larger prostates. Higher number of cores increases both significant and insignificant tumor detection probability, but predominantly increases the detection of insignificant tumors. The study demonstrates mathematically that the geometric biopsy schema plays an important clinical role, and that increasing the number of biopsy cores is not necessarily helpful.

  11. Testing for Expected Return and Market Price of Risk in Chinese A-B Share Market: A Geometric Brownian Motion and Multivariate GARCH Model Approach

    DEFF Research Database (Denmark)

    Zhu, Jie

    There exist dual-listed stocks which are issued by the same company in some stock markets. Although these stocks bare the same firm-specific risk and enjoy identical dividends and voting policies, they are priced differently. Some previous studies show this seeming deviation from the law of one...... price can be solved due to different ex- pected return and market price of risk for investors holding heterogeneous beliefs. This paper provides empirical evidence for that argument by testing the expected return and market price of risk between Chinese A and B shares listed in Shanghai and Shenzhen...... stock markets. Models with dynamic of Geometric Brownian Motion are adopted, multivariate GARCH models are also introduced to capture the feature of time-varying volatility in stock returns. The results suggest that the different pric- ing can be explained by the difference in expected returns between...

  12. Testing for Expected Return and Market Price of Risk in Chinese A-B Share Market: A Geometric Brownian Motion and Multivariate GARCH Model Approach

    DEFF Research Database (Denmark)

    Zhu, Jie

    There exist dual-listed stocks which are issued by the same company in some stock markets. Although these stocks bare the same firm-specific risk and enjoy identical dividends and voting policies, they are priced differently. Some previous studies show this seeming deviation from the law of one...... price can be solved due to different ex- pected return and market price of risk for investors holding heterogeneous beliefs. This paper provides empirical evidence for that argument by testing the expected return and market price of risk between Chinese A and B shares listed in Shanghai and Shenzhen...... stock markets. Models with dynamic of Geometric Brownian Motion are adopted, multivariate GARCH models are also introduced to capture the feature of time-varying volatility in stock returns. The results suggest that the different pric- ing can be explained by the difference in expected returns between...

  13. Diffraction of a Gaussian beam in a three-dimensional smoothly inhomogeneous medium: an eikonal-based complex geometrical-optics approach.

    Science.gov (United States)

    Berczynski, Pawel; Bliokh, Konstantin Yu; Kravtsov, Yuri A; Stateczny, Andrzej

    2006-06-01

    We present an ab initio account of the paraxial complex geometrical optics (CGO) in application to scalar Gaussian beam propagation and diffraction in a 3D smoothly inhomogeneous medium. The paraxial CGO deals with quadratic expansion of the complex eikonal and reduces the wave problem to the solution of ordinary differential equations of the Riccati type. This substantially simplifies the description of Gaussian beam diffraction as compared with full-wave or parabolic (quasi-optics) equations. For a Gaussian beam propagating in a homogeneous medium or along the symmetry axis in a lenslike medium, the CGO equations possess analytical solutions; otherwise, they can be readily solved numerically. As a nontrivial example we consider Gaussian beam propagation and diffraction along a helical ray in an axially symmetric waveguide medium. It is shown that the major axis of the beam's elliptical cross section grows unboundedly; it is oriented predominantly in the azimuthal (binormal) direction and does not obey the parallel-transport law.

  14. Hierarchical Geometric Constraint Model for Parametric Feature Based Modeling

    Institute of Scientific and Technical Information of China (English)

    高曙明; 彭群生

    1997-01-01

    A new geometric constraint model is described,which is hierarchical and suitable for parametric feature based modeling.In this model,different levels of geometric information are repesented to support various stages of a design process.An efficient approach to parametric feature based modeling is also presented,adopting the high level geometric constraint model.The low level geometric model such as B-reps can be derived automatically from the hig level geometric constraint model,enabling designers to perform their task of detailed design.

  15. Science, Art and Geometrical Imagination

    CERN Document Server

    Luminet, J -P

    2009-01-01

    From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental role of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Durer, Kepler, Escher, Grisey or the present author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as beauty, conciseness and emotional approach of the world.

  16. Science, art and geometrical imagination

    Science.gov (United States)

    Luminet, Jean-Pierre

    2011-06-01

    From the geocentric, closed world model of Antiquity to the wraparound universe models of relativistic cosmology, the parallel history of space representations in science and art illustrates the fundamental rôle of geometric imagination in innovative findings. Through the analysis of works of various artists and scientists like Plato, Dürer, Kepler, Escher, Grisey or the author, it is shown how the process of creation in science and in the arts rests on aesthetical principles such as symmetry, regular polyhedra, laws of harmonic proportion, tessellations, group theory, etc., as well as on beauty, conciseness and an emotional approach of the world.

  17. Study on the Grey Polynomial Geometric Programming

    Institute of Scientific and Technical Information of China (English)

    LUODang

    2005-01-01

    In the model of geometric programming, values of parameters cannot be gotten owing to data fluctuation and incompletion. But reasonable bounds of these parameters can be attained. This is to say, parameters of this model can be regarded as interval grey numbers. When the model contains grey numbers, it is hard for common programming method to solve them. By combining the common programming model with the grey system theory,and using some analysis strategies, a model of grey polynomial geometric programming, a model of 8 positioned geometric programming and their quasi-optimum solution or optimum solution are put forward. At the same time, we also developed an algorithm for the problem.This approach brings a new way for the application research of geometric programming. An example at the end of this paper shows the rationality and feasibility of the algorithm.

  18. Morphometrical diagnosis of the malaria vectors Anopheles cruzii, An. homunculus and An. bellator

    Directory of Open Access Journals (Sweden)

    Lorenz Camila

    2012-11-01

    Full Text Available Abstract Background Anopheles (Kerteszia cruzii is a primary vector of Plasmodium parasites in Brazil’s Atlantic Forest. Adult females of An. cruzii and An. homunculus, which is a secondary malaria vector, are morphologically similar and difficult to distinguish when using external morphological characteristics only. These two species may occur syntopically with An. bellator, which is also a potential vector of Plasmodium species and is morphologically similar to An. cruzii and An. homunculus. Identification of these species based on female specimens is often jeopardised by polymorphisms, overlapping morphological characteristics and damage caused to specimens during collection. Wing geometric morphometrics has been used to distinguish several insect species; however, this economical and powerful tool has not been applied to Kerteszia species. Our objective was to assess wing geometry to distinguish An. cruzii, An. homunculus and An. bellator. Methods Specimens were collected in an area in the Serra do Mar hotspot biodiversity corridor of the Atlantic Forest biome (Cananeia municipality, State of Sao Paulo, Brazil. The right wings of females of An. cruzii (n= 40, An. homunculus (n= 50 and An. bellator (n= 27 were photographed. For each individual, 18 wing landmarks were subjected to standard geometric morphometrics. Discriminant analysis of Procrustean coordinates was performed to quantify wing shape variation. Results Individuals clustered into three distinct groups according to species with a slight overlap between representatives of An. cruzii and An. homunculus. The Mahalanobis distance between An. cruzii and An. homunculus was consistently lower (3.50 than that between An. cruzii and An. bellator (4.58 or An. homunculus and An. bellator (4.32. Pairwise cross-validated reclassification showed that geometric morphometrics is an effective analytical method to distinguish between An. bellator, An. cruzii and An. homunculus with a reliability

  19. Quantitative histo-morphometric analysis of heat-stress-related damage in the small intestines of broiler chickens

    NARCIS (Netherlands)

    Santos, Regiane R.; Awati, Ajay; Roubos-van den Hil, Petra J.; Tersteeg-Zijderveld, Monique H. G.; Koolmees, Peter A.; Fink-Gremmels, Johanna

    2015-01-01

    The aim of the current research was to present a methodological approach allowing reproducible morphometric and morphological (Chiu/Park scale) analyses of the alterations in the intestines of broilers exposed to heat stress. Ross broilers were exposed over four consecutive days to a high-temperatur

  20. PREFACE: Geometrically frustrated magnetism Geometrically frustrated magnetism

    Science.gov (United States)

    Gardner, Jason S.

    2011-04-01

    Frustrated magnetism is an exciting and diverse field in condensed matter physics that has grown tremendously over the past 20 years. This special issue aims to capture some of that excitement in the field of geometrically frustrated magnets and is inspired by the 2010 Highly Frustrated Magnetism (HFM 2010) meeting in Baltimore, MD, USA. Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry based on triangles and tetrahedra. Most studies have centred around the kagomé and pyrochlore based magnets but recent work has looked at other structures including the delafossite, langasites, hyper-kagomé, garnets and Laves phase materials to name a few. Personally, I hope this issue serves as a great reference to scientist both new and old to this field, and that we all continue to have fun in this very frustrated playground. Finally, I want to thank the HFM 2010 organizers and all the sponsors whose contributions were an essential part of the success of the meeting in Baltimore. Geometrically frustrated magnetism contents Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? T Fennell, J O Piatek, R A Stephenson, G J Nilsen and H M Rønnow Two-dimensional magnetism and spin-size effect in the S = 1 triangular antiferromagnet NiGa2S4 Yusuke Nambu and Satoru Nakatsuji Short range ordering in the modified honeycomb lattice compound SrHo2O4 S Ghosh, H D Zhou, L Balicas, S Hill, J S Gardner, Y Qi and C R Wiebe Heavy fermion compounds on the geometrically frustrated Shastry-Sutherland lattice M S Kim and M C Aronson A neutron polarization analysis study of moment correlations in (Dy0.4Y0.6)T2 (T = Mn, Al) J R Stewart, J M Hillier, P Manuel and R Cywinski Elemental analysis and magnetism of hydronium jarosites—model kagome antiferromagnets and topological spin glasses A S Wills and W G Bisson The Herbertsmithite Hamiltonian: μSR measurements on single crystals

  1. Mahavira's Geometrical Problems

    DEFF Research Database (Denmark)

    Høyrup, Jens

    2004-01-01

    Analysis of the geometrical chapters Mahavira's 9th-century Ganita-sara-sangraha reveals inspiration from several chronological levels of Near-Eastern and Mediterranean mathematics: (1)that known from Old Babylonian tablets, c. 1800-1600 BCE; (2)a Late Babylonian but pre-Seleucid Stratum, probably...

  2. Untangling Geometric Ideas

    Science.gov (United States)

    Burgess, Claudia R.

    2014-01-01

    Designed for a broad audience, including educators, camp directors, afterschool coordinators, and preservice teachers, this investigation aims to help individuals experience mathematics in unconventional and exciting ways by engaging them in the physical activity of building geometric shapes using ropes. Through this engagement, the author…

  3. Pragmatic geometric model evaluation

    Science.gov (United States)

    Pamer, Robert

    2015-04-01

    Quantification of subsurface model reliability is mathematically and technically demanding as there are many different sources of uncertainty and some of the factors can be assessed merely in a subjective way. For many practical applications in industry or risk assessment (e. g. geothermal drilling) a quantitative estimation of possible geometric variations in depth unit is preferred over relative numbers because of cost calculations for different scenarios. The talk gives an overview of several factors that affect the geometry of structural subsurface models that are based upon typical geological survey organization (GSO) data like geological maps, borehole data and conceptually driven construction of subsurface elements (e. g. fault network). Within the context of the trans-European project "GeoMol" uncertainty analysis has to be very pragmatic also because of different data rights, data policies and modelling software between the project partners. In a case study a two-step evaluation methodology for geometric subsurface model uncertainty is being developed. In a first step several models of the same volume of interest have been calculated by omitting successively more and more input data types (seismic constraints, fault network, outcrop data). The positions of the various horizon surfaces are then compared. The procedure is equivalent to comparing data of various levels of detail and therefore structural complexity. This gives a measure of the structural significance of each data set in space and as a consequence areas of geometric complexity are identified. These areas are usually very data sensitive hence geometric variability in between individual data points in these areas is higher than in areas of low structural complexity. Instead of calculating a multitude of different models by varying some input data or parameters as it is done by Monte-Carlo-simulations, the aim of the second step of the evaluation procedure (which is part of the ongoing work) is to

  4. Additivity rule for electron-molecule total cross section calculations at 50-5000 eV: a new geometrical approach

    Institute of Scientific and Technical Information of China (English)

    Shi De-Heng; Sun Jin-Feng; Zhu Zun-Lüe; Liu Yu-Fang

    2008-01-01

    Taking into consideration the changes of the geometric shielding effect in a molecule as the energy of incident electrons varies, this paper presents an empirical fraction, which depends on the energy of incident electrons, the target's molecular dimension and the atomic and electronic numbers in the molecule. Using this empirical fraction, it proposes a new formulation of the additivity rule. Employing the new additivity rule, it calculates the total cross sections of electron scattering by C2H4, C6H8, C6H14 and C8H18 over the energy range from 50 to 5000eV. In order to exclude the calculation deviations caused by solving the radial SchriJdinger equation of electron scattering by atoms, here the atomic cross sections are derived from the experimental total cross section results of simple molecules (H2,O2, CO) via the inversion algorithm. The quantitative total cross sections are compared with those obtained by experiments and other theories, and good agreement is obtained over a wide energy range, even at energy of several tens of eV.

  5. A simple geometric validation approach to assess the basic behaviour of space- and time- distributed models of epidemic spread - an example using the Ontario rabies model.

    Science.gov (United States)

    Ludwig, A; Berthiaume, P; Richer, J; Tinline, R; Bigras-Poulin, M

    2014-04-01

    Dynamic mathematical modelling and stochastic simulation of disease-host systems for the purpose of epidemiological analysis offer great opportunities for testing hypotheses, especially when field experiments are impractical or when there is a need to evaluate multiple experimental scenarios. This, combined with the ever increasing computer power available to researchers, has contributed to the development of many mathematical models for epidemic simulations, such as the individual-based model (IBM). Nevertheless, few of these models undergo extensive validation and proper assessment of intrinsic variability. The Ontario rabies model (ORM) will be used here to exemplify some advantages of appropriate model behaviour validation and to illustrate the use of a simple geometric procedure for testing directional bias in distributed stochastic dynamic model of spread of diseases. Results were obtained through the comparison of 10 000 epizootics resulting from 100 epidemic simulations started using 100 distinct base populations. The analysis results demonstrated a significant directional bias in epidemic dispersion, which prompted further verification of the model code and the identification of a coding error, which was then corrected. Subsequent testing of the corrected code showed that the directional bias could no longer be detected. These results illustrate the importance of proper validation and the importance of sufficient knowledge of the model behaviour to ensure the results will not confound the objectives of the end-users.

  6. Estimating population age structure using otolith morphometrics

    DEFF Research Database (Denmark)

    Doering-Arjes, P.; Cardinale, M.; Mosegaard, Henrik

    2008-01-01

    known-age fish individuals. Here we used known-age Atlantic cod (Gadus morhua) from the Faroe Bank and Faroe Plateau stocks. Cod populations usually show quite large variation in growth rates and otolith shape. We showed that including otolith morphometrics into ageing processes has the potential...... to make ageing objective, accurate, and fast. Calibration analysis indicated that a known-age sample from the same population and environment is needed to obtain robust calibration; using a sample from a different stock more than doubles the error rate, even in the case of genetically highly related...... populations. The intercalibration method was successful but generalization from one stock to another remains problematic. The development of an otolith growth model is needed for generalization if an operational method for different populations is required in the future....

  7. Morphometric analysis of Willis circle arteries

    Directory of Open Access Journals (Sweden)

    Alma Voljevica

    2013-01-01

    Full Text Available Introduction: Willis arterial circle (circulus arteriosus cerebri Willisi is the most important part of the collateral circulatory system of the brain. It functions in normal and pathological situations such as valvular mechanism and thus allows optimal blood supply of all parts of the brain tissue, which reduces the risk of transient ischemic attack (TIA and stroke. The main pre-requisite for the normal function of the circle is its completeness and the lack of hypoplastic vessels. Materials and Methods: In this research, we used 100 angiograms of carotid system shown by serial angiography by Seldinger taken from the archives of the Department of Radiology, Clinical Center University of Sarajevo. For morphometric analysis of blood vessels, we used specially designed software program ELLIPSE (ViDiTo, Zoltan Tomoris, Kosice, Slovak Republic, tomori@saske.sk. In this way, it was possible to more easily store and analyze angiograms that were used for morphometric analysis. Results: In our study, larger diameters of blood vessels in Willis circle were observed in the younger subjects compared to older except the diameter of the internal carotid artery, which was about 0.2 to 0.3 mm larger in the older subjects. In both age groups among males, we recorded larger diameters of the internal carotid artery and segment before the circle of the posterior cerebral artery in relation to the female population, while the rear communicating artery in females was 0.1 mm wider in diameter compared to men in category of younger respondents.

  8. The spinning apparatus of webspinners--functional-morphology, morphometrics and spinning behaviour.

    Science.gov (United States)

    Büsse, Sebastian; Hörnschemeyer, Thomas; Hohu, Kyle; McMillan, David; Edgerly, Janice S

    2015-05-07

    Webspinners (Insecta: Embioptera) have a distinctly unique behaviour with related morphological characteristics. Producing silk with the basitarsomeres of their forelegs plays a crucial role in the lives of these insects--providing shelter and protection. The correlation between body size, morphology and morphometrics of the spinning apparatus and the spinning behaviour of Embioptera was investigated for seven species using state-of-the-art methodology for behavioural as well as for morphological approaches. Independent contrast analysis revealed correlations between morphometric characters and body size. Larger webspinners in this study have glands with greater reservoir volume, but in proportionally smaller tarsi relative to body size than in the smaller species. Furthermore, we present a detailed description and review of the spinning apparatus in Embioptera in comparison to other arthropods and substantiate the possible homology of the embiopteran silk glands to class III dermal silk glands of insects.

  9. The spinning apparatus of webspinners – functional-morphology, morphometrics and spinning behaviour

    Science.gov (United States)

    Büsse, Sebastian; Hörnschemeyer, Thomas; Hohu, Kyle; McMillan, David; Edgerly, Janice S.

    2015-01-01

    Webspinners (Insecta: Embioptera) have a distinctly unique behaviour with related morphological characteristics. Producing silk with the basitarsomeres of their forelegs plays a crucial role in the lives of these insects – providing shelter and protection. The correlation between body size, morphology and morphometrics of the spinning apparatus and the spinning behaviour of Embioptera was investigated for seven species using state-of-the-art methodology for behavioural as well as for morphological approaches. Independent contrast analysis revealed correlations between morphometric characters and body size. Larger webspinners in this study have glands with greater reservoir volume, but in proportionally smaller tarsi relative to body size than in the smaller species. Furthermore, we present a detailed description and review of the spinning apparatus in Embioptera in comparison to other arthropods and substantiate the possible homology of the embiopteran silk glands to class III dermal silk glands of insects. PMID:25950122

  10. Geometrical Methods for Power Network Analysis

    CERN Document Server

    Bellucci, Stefano; Gupta, Neeraj

    2013-01-01

    This book is a short introduction to power system planning and operation using advanced geometrical methods. The approach is based on well-known insights and techniques developed in theoretical physics in the context of Riemannian manifolds. The proof of principle and robustness of this approach is examined in the context of the IEEE 5 bus system. This work addresses applied mathematicians, theoretical physicists and power engineers interested in novel mathematical approaches to power network theory.

  11. Morphometric study of phylogenetic and ecologic signals in procyonid (mammalia: carnivora) endocasts.

    Science.gov (United States)

    Ahrens, Heather E

    2014-12-01

    Endocasts provide a proxy for brain morphology but are rarely incorporated in phylogenetic analyses despite the potential for new suites of characters. The phylogeny of Procyonidae, a carnivoran family with relatively limited taxonomic diversity, is not well resolved because morphological and molecular data yield conflicting topologies. The presence of phylogenetic and ecologic signals in the endocasts of procyonids will be determined using three-dimensional geometric morphometrics. Endocasts of seven ingroup species and four outgroup species were digitally rendered and 21 landmarks were collected from the endocast surface. Two phylogenetic hypotheses of Procyonidae will be examined using methods testing for phylogenetic signal in morphometric data. In analyses of all taxa, there is significant phylogenetic signal in brain shape for both the morphological and molecular topologies. However, the analyses of ingroup taxa recover a significant phylogenetic signal for the morphological topology only. These results indicate support for the molecular outgroup topology, but not the ingroup topology given the brain shape data. Further examination of brain shape using principal components analysis and wireframe comparisons suggests procyonids possess more developed areas of the brain associated with motor control, spatial perception, and balance relative to the basal musteloid condition. Within Procyonidae, similar patterns of variation are present, and may be associated with increased arboreality in certain taxa. Thus, brain shape derived from endocasts may be used to test for phylogenetic signal and preliminary analyses suggest an association with behavior and ecology.

  12. Geometric Approach in Coexistence with Maturalism in Norwegian Landscape Architecture from 1920 through 1970%几何式与自然主义的并存:1920-1970年间的挪威园林

    Institute of Scientific and Technical Information of China (English)

    蒙小英; 王向荣

    2011-01-01

    Two directions— geometric approach and naturalism could be recognized in the period of 1920-1970 in Norwegian landscape architecture, which were influenced by natural landscape, Classicism and Functionalism. It led to the geometric approach in coexistence with naturalistic styte in Norwegian landscape architecture, even extending into today. During the period Modern Norwegian landscape archiecture featured this coexistence if compared with other Nordic countries. Based on the field works and literatures, this paper mainly examines the works finished in the period by the noticed Norwegian landscape architects, including Olav L. Moen, Marius Rohne, Karen Reistad and Egil Gabrielsen. It targets to summarize the features and demonstrate the involved details of their works Moen's classical design language, Rohne's functionalism park policy, Reistad's poetic functionalism inspired by the naturalism, and Gabrielsen's geometric approach influenced by the works of Mies van der Rohe( 1886- 1969).%1920-1970年间挪威风景园林师秉承对本士自然景观的热爱,在新古典主义遗风和功能主义的影响下,创造出迥异于其他北欧国家的二元特征-几何式与自然主义并存的二元风格,并一直延续至今.以现场调研和文献资料为基础,重点介绍了1920-1970年间挪威知名风景园林师莫恩、罗内、莱西塔和盖布瑞尔森在这50年问的代表作品,以廓清设计师各自作品中所呈现出的风格特征与内涵:莫恩的新占典设计语言,罗内的功能主义公园建设主张,莱西塔有明显自然主义倾向的诗意功能主义,以及盖布瑞尔森受密斯影响的儿何式园林风格.

  13. Polar Metals by Geometric Design

    Energy Technology Data Exchange (ETDEWEB)

    Kim, T. H.; Puggioni, D.; Yuan, Y.; Xie, L.; Zhou, H.; Campbell, N.; Ryan, P. J.; Choi, Y.; Kim, J. -W.; Patzner, J. R.; Ryu, S.; Podkaminer, J. P.; Irwin, J.; Ma, Y.; Fennie, C. J.; Rzchowski, M. S.; Pan, X. Q.; Gopalan, V.; Rondinelli, J. M.; Eom, C. B.

    2016-05-05

    Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that may arise owing to asymmetric charge distributions(1). Quantum physics supports this view(2), demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals(3)-it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases(4). Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO(3) perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements(5). We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedra-the structural signatures of perovskites-owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported(6-10), non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.

  14. Gravity, a geometrical course

    CERN Document Server

    Frè, Pietro Giuseppe

    2013-01-01

    ‘Gravity, a Geometrical Course’ presents general relativity (GR) in a systematic and exhaustive way, covering three aspects that are homogenized into a single texture: i) the mathematical, geometrical foundations, exposed in a self consistent contemporary formalism, ii) the main physical, astrophysical and cosmological applications,  updated to the issues of contemporary research and observations, with glimpses on supergravity and superstring theory, iii) the historical development of scientific ideas underlying both the birth of general relativity and its subsequent evolution. The book is divided in two volumes.   Volume One is dedicated to the development of the theory and basic physical applications. It guides the reader from the foundation of special relativity to Einstein field equations, illustrating some basic applications in astrophysics. A detailed  account  of the historical and conceptual development of the theory is combined with the presentation of its mathematical foundations.  Differe...

  15. Testing algebraic geometric codes

    Institute of Scientific and Technical Information of China (English)

    CHEN Hao

    2009-01-01

    Property testing was initially studied from various motivations in 1990's.A code C (∩)GF(r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector's coordinates.The problem of testing codes was firstly studied by Blum,Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs).How to characterize locally testable codes is a complex and challenge problem.The local tests have been studied for Reed-Solomon (RS),Reed-Muller (RM),cyclic,dual of BCH and the trace subcode of algebraicgeometric codes.In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions).We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.

  16. Geometric group theory

    CERN Document Server

    Bestvina, Mladen; Vogtmann, Karen

    2014-01-01

    Geometric group theory refers to the study of discrete groups using tools from topology, geometry, dynamics and analysis. The field is evolving very rapidly and the present volume provides an introduction to and overview of various topics which have played critical roles in this evolution. The book contains lecture notes from courses given at the Park City Math Institute on Geometric Group Theory. The institute consists of a set of intensive short courses offered by leaders in the field, designed to introduce students to exciting, current research in mathematics. These lectures do not duplicate standard courses available elsewhere. The courses begin at an introductory level suitable for graduate students and lead up to currently active topics of research. The articles in this volume include introductions to CAT(0) cube complexes and groups, to modern small cancellation theory, to isometry groups of general CAT(0) spaces, and a discussion of nilpotent genus in the context of mapping class groups and CAT(0) gro...

  17. Testing algebraic geometric codes

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Property testing was initially studied from various motivations in 1990’s. A code C  GF (r)n is locally testable if there is a randomized algorithm which can distinguish with high possibility the codewords from a vector essentially far from the code by only accessing a very small (typically constant) number of the vector’s coordinates. The problem of testing codes was firstly studied by Blum, Luby and Rubinfeld and closely related to probabilistically checkable proofs (PCPs). How to characterize locally testable codes is a complex and challenge problem. The local tests have been studied for Reed-Solomon (RS), Reed-Muller (RM), cyclic, dual of BCH and the trace subcode of algebraicgeometric codes. In this paper we give testers for algebraic geometric codes with linear parameters (as functions of dimensions). We also give a moderate condition under which the family of algebraic geometric codes cannot be locally testable.

  18. Dynamics in geometrical confinement

    CERN Document Server

    Kremer, Friedrich

    2014-01-01

    This book describes the dynamics of low molecular weight and polymeric molecules when they are constrained under conditions of geometrical confinement. It covers geometrical confinement in different dimensionalities: (i) in nanometer thin layers or self supporting films (1-dimensional confinement) (ii) in pores or tubes with nanometric diameters (2-dimensional confinement) (iii) as micelles embedded in matrices (3-dimensional) or as nanodroplets.The dynamics under such conditions have been a much discussed and central topic in the focus of intense worldwide research activities within the last two decades. The present book discusses how the resulting molecular mobility is influenced by the subtle counterbalance between surface effects (typically slowing down molecular dynamics through attractive guest/host interactions) and confinement effects (typically increasing the mobility). It also explains how these influences can be modified and tuned, e.g. through appropriate surface coatings, film thicknesses or pore...

  19. Resampling-based approaches to study variation in morphological modularity.

    Directory of Open Access Journals (Sweden)

    Carmelo Fruciano

    Full Text Available Modularity has been suggested to be connected to evolvability because a higher degree of independence among parts allows them to evolve as separate units. Recently, the Escoufier RV coefficient has been proposed as a measure of the degree of integration between modules in multivariate morphometric datasets. However, it has been shown, using randomly simulated datasets, that the value of the RV coefficient depends on sample size. Also, so far there is no statistical test for the difference in the RV coefficient between a priori defined groups of observations. Here, we (1, using a rarefaction analysis, show that the value of the RV coefficient depends on sample size also in real geometric morphometric datasets; (2 propose a permutation procedure to test for the difference in the RV coefficient between a priori defined groups of observations; (3 show, through simulations, that such a permutation procedure has an appropriate Type I error; (4 suggest that a rarefaction procedure could be used to obtain sample-size-corrected values of the RV coefficient; and (5 propose a nearest-neighbor procedure that could be used when studying the variation of modularity in geographic space. The approaches outlined here, readily extendable to non-morphometric datasets, allow study of the variation in the degree of integration between a priori defined modules. A Java application--that will allow performance of the proposed test using a software with graphical user interface--has also been developed and is available at the Morphometrics at Stony Brook Web page (http://life.bio.sunysb.edu/morph/.

  20. Progressive geometric algorithms

    Directory of Open Access Journals (Sweden)

    Sander P.A. Alewijnse

    2015-01-01

    Full Text Available Progressive algorithms are algorithms that, on the way to computing a complete solution to the problem at hand, output intermediate solutions that approximate the complete solution increasingly well. We present a framework for analyzing such algorithms, and develop efficient progressive algorithms for two geometric problems: computing the convex hull of a planar point set, and finding popular places in a set of trajectories.

  1. Geometric Time Delay Interferometry

    OpenAIRE

    Vallisneri, Michele

    2005-01-01

    The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...

  2. Geometric unsharpness calculations

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.J. [International Training and Education Group (INTEG), Oakville, Ontario (Canada)

    2008-07-15

    The majority of radiographers' geometric unsharpness calculations are normally performed with a mathematical formula. However, a majority of codes and standards refer to the use of a nomograph for this calculation. Upon first review, the use of a nomograph appears more complicated but with a few minutes of study and practice it can be just as effective. A review of this article should provide enlightenment. (author)

  3. Geometric Stochastic Resonance

    CERN Document Server

    Ghosh, Pulak Kumar; Savel'ev, Sergey E; Nori, Franco

    2015-01-01

    A Brownian particle moving across a porous membrane subject to an oscillating force exhibits stochastic resonance with properties which strongly depend on the geometry of the confining cavities on the two sides of the membrane. Such a manifestation of stochastic resonance requires neither energetic nor entropic barriers, and can thus be regarded as a purely geometric effect. The magnitude of this effect is sensitive to the geometry of both the cavities and the pores, thus leading to distinctive optimal synchronization conditions.

  4. Geometric properties of eigenfunctions

    Energy Technology Data Exchange (ETDEWEB)

    Jakobson, D; Nadirashvili, N [McGill University, Montreal, Quebec (Canada); Toth, John [University of Chicago, Chicago, Illinois (United States)

    2001-12-31

    We give an overview of some new and old results on geometric properties of eigenfunctions of Laplacians on Riemannian manifolds. We discuss properties of nodal sets and critical points, the number of nodal domains, and asymptotic properties of eigenfunctions in the high-energy limit (such as weak * limits, the rate of growth of L{sup p} norms, and relationships between positive and negative parts of eigenfunctions)

  5. Geometric theory of information

    CERN Document Server

    2014-01-01

    This book brings together geometric tools and their applications for Information analysis. It collects current and many uses of in the interdisciplinary fields of Information Geometry Manifolds in Advanced Signal, Image & Video Processing, Complex Data Modeling and Analysis, Information Ranking and Retrieval, Coding, Cognitive Systems, Optimal Control, Statistics on Manifolds, Machine Learning, Speech/sound recognition, and natural language treatment which are also substantially relevant for the industry.

  6. A new morphometric implemented video-image analysis protocol for the study of social modulation in activity rhythms of marine organisms.

    Science.gov (United States)

    Menesatti, Paolo; Aguzzi, Jacopo; Costa, Corrado; García, José Antonio; Sardà, Francesc

    2009-10-30

    Video-image analysis can be an efficient tool for microcosm experiments portraying the modulation of individual behaviour based on sociality. The Norway lobster, Nephrops norvegicus is a burrowing decapod the commercial capture of which occurs by trawling only when animals are engaged in seabed excursions. Emergence behaviour is modulated by the day-night cycle but a further modulation occurs upon social interaction in a still unknown fashion. Here, we present a novel automated protocol for the tracking of the movement of different animals at once based on a multivariate morphometric approach. Four black and white tags were customized according to a precise geometric design. Shape Matching and Complex Fourier Descriptors analyses were used to track tag displacement through consecutive frames in a 7-day experiment under monochromatic blue light (480 nm)-darkness conditions. Shape Matching errors were evaluated in relation to tag geometry. Time series of centroid coordinates in pixels were transformed in centimetres. The FD analysis was slightly less efficient than the Shape Matching, although more rapid (i.e. up to 20 times faster). Nocturnal rhythms were reported for all animals. Waveform analysis indicated marked differences in the amplitude of activity phases as proof of interindividual interaction. Total diel activity presented a decrease in the rate of out of burrow locomotion as the testing progressed. N. norvegicus is a nocturnal species and present observations sustain the efficiency and fidelity of our automated tracking system.

  7. Morphometric comparisons of plant-mimetic juvenile fish associated with plant debris observed in the coastal subtropical waters around Kuchierabu-jima Island, southern Japan

    Science.gov (United States)

    2016-01-01

    The general morphological shape of plant-resembling fish and plant parts were compared using a geometric morphometrics approach. Three plant-mimetic fish species, Lobotes surinamensis (Lobotidae), Platax orbicularis (Ephippidae) and Canthidermis maculata (Balistidae), were compared during their early developmental stages with accompanying plant debris (i.e., leaves of several taxa) in the coastal subtropical waters around Kuchierabu-jima Island, closely facing the Kuroshio Current. The degree of similarity shared between the plant parts and co-occurring fish species was quantified, however fish remained morphologically distinct from their plant models. Such similarities were corroborated by analysis of covariance and linear discriminant analysis, in which relative body areas of fish were strongly related to plant models. Our results strengthen the paradigm that morphological clues can lead to ecological evidence to allow predictions of behavioural and habitat choice by mimetic fish, according to the degree of similarity shared with their respective models. The resemblance to plant parts detected in the three fish species may provide fitness advantages via convergent evolutionary effects. PMID:27547571

  8. Morphometric comparisons of plant-mimetic juvenile fish associated with plant debris observed in the coastal subtropical waters around Kuchierabu-jima Island, southern Japan.

    Science.gov (United States)

    de Queiroz, Alexya Cunha; Sakai, Yoichi; Vallinoto, Marcelo; Barros, Breno

    2016-01-01

    The general morphological shape of plant-resembling fish and plant parts were compared using a geometric morphometrics approach. Three plant-mimetic fish species, Lobotes surinamensis (Lobotidae), Platax orbicularis (Ephippidae) and Canthidermis maculata (Balistidae), were compared during their early developmental stages with accompanying plant debris (i.e., leaves of several taxa) in the coastal subtropical waters around Kuchierabu-jima Island, closely facing the Kuroshio Current. The degree of similarity shared between the plant parts and co-occurring fish species was quantified, however fish remained morphologically distinct from their plant models. Such similarities were corroborated by analysis of covariance and linear discriminant analysis, in which relative body areas of fish were strongly related to plant models. Our results strengthen the paradigm that morphological clues can lead to ecological evidence to allow predictions of behavioural and habitat choice by mimetic fish, according to the degree of similarity shared with their respective models. The resemblance to plant parts detected in the three fish species may provide fitness advantages via convergent evolutionary effects.

  9. Perspective: Geometrically frustrated assemblies

    Science.gov (United States)

    Grason, Gregory M.

    2016-09-01

    This perspective will overview an emerging paradigm for self-organized soft materials, geometrically frustrated assemblies, where interactions between self-assembling elements (e.g., particles, macromolecules, proteins) favor local packing motifs that are incompatible with uniform global order in the assembly. This classification applies to a broad range of material assemblies including self-twisting protein filament bundles, amyloid fibers, chiral smectics and membranes, particle-coated droplets, curved protein shells, and phase-separated lipid vesicles. In assemblies, geometric frustration leads to a host of anomalous structural and thermodynamic properties, including heterogeneous and internally stressed equilibrium structures, self-limiting assembly, and topological defects in the equilibrium assembly structures. The purpose of this perspective is to (1) highlight the unifying principles and consequences of geometric frustration in soft matter assemblies; (2) classify the known distinct modes of frustration and review corresponding experimental examples; and (3) describe outstanding questions not yet addressed about the unique properties and behaviors of this broad class of systems.

  10. The quantum geometric limit

    CERN Document Server

    Lloyd, Seth

    2012-01-01

    This letter analyzes the limits that quantum mechanics imposes on the accuracy to which spacetime geometry can be measured. By applying the fundamental physical bounds to measurement accuracy to ensembles of clocks and signals moving in curved spacetime -- e.g., the global positioning system -- I derive a covariant version of the quantum geometric limit: the total number of ticks of clocks and clicks of detectors that can be contained in a four volume of spacetime of radius r and temporal extent t is less than or equal to rt/\\pi x_P t_P, where x_P, t_P are the Planck length and time. The quantum geometric limit bounds the number of events or `ops' that can take place in a four-volume of spacetime: each event is associated with a Planck-scale area. Conversely, I show that if each quantum event is associated with such an area, then Einstein's equations must hold. The quantum geometric limit is consistent with and complementary to the holographic bound which limits the number of bits that can exist within a spat...

  11. Morphometric variation in the forest rodent Malacomys edwardsi ...

    African Journals Online (AJOL)

    SARAH

    2014-08-31

    Aug 31, 2014 ... Morphometric variation in the forest rodent Malacomys edwardsi in Côte d' ... This genus only occurs in tropical regions of Africa. ... complex, Jacquet et al., 2014). ..... structure matrix indicates that LOTE, BULL, UPDA and.

  12. 13 Morphometric Analysis of Ogunpa and Ogbere Drainage Basins ...

    African Journals Online (AJOL)

    `123456789jkl''''#

    Morphometric Analysis of Ogunpa and Ogbere Drainage Basins, Ibadan, Nigeria. *Ajibade ... complex rock in Southwestern Nigeria. .... This work was based on map analysis ..... Bs = VI/HE where Bs = Basin slope, VI = Vertical Interval and.

  13. Geometric diffusion of quantum trajectories.

    Science.gov (United States)

    Yang, Fan; Liu, Ren-Bao

    2015-07-16

    A quantum object can acquire a geometric phase (such as Berry phases and Aharonov-Bohm phases) when evolving along a path in a parameter space with non-trivial gauge structures. Inherent to quantum evolutions of wavepackets, quantum diffusion occurs along quantum trajectories. Here we show that quantum diffusion can also be geometric as characterized by the imaginary part of a geometric phase. The geometric quantum diffusion results from interference between different instantaneous eigenstate pathways which have different geometric phases during the adiabatic evolution. As a specific example, we study the quantum trajectories of optically excited electron-hole pairs in time-reversal symmetric insulators, driven by an elliptically polarized terahertz field. The imaginary geometric phase manifests itself as elliptical polarization in the terahertz sideband generation. The geometric quantum diffusion adds a new dimension to geometric phases and may have applications in many fields of physics, e.g., transport in topological insulators and novel electro-optical effects.

  14. Geometric covering arguments and ergodic theorems for free groups

    CERN Document Server

    Bowen, Lewis

    2009-01-01

    We present a new approach to the proof of ergodic theorems for actions of free groups based on geometric covering and asymptotic invariance arguments. Our approach can be viewed as a direct generalization of the classical geometric covering and asymptotic invariance arguments used in the ergodic theory of amenable groups. We use this approach to generalize the existing maximal and pointwise ergodic theorems for free group actions to a large class of geometric averages which were not accessible by previous techniques. Some applications of our approach to other groups and other problems in ergodic theory are also briefly discussed.

  15. Current status and potential of morphometric sperm analysis

    OpenAIRE

    Alejandro Maroto-Morales; Olga García-Álvarez; Manuel Ramón; Felipe Martínez-Pastor; M Rocío Fernández-Santos; A Josefa Soler; José Julián Garde

    2016-01-01

    The spermatozoon is the most diverse cell type known and this diversity is considered to reflect differences in sperm function. How the diversity in sperm morphology arose during speciation and what role the different specializations play in sperm function, however, remain incompletely characterized. This work reviews the hypotheses proposed to explain sperm morphological evolution, with a focus on some aspects of sperm morphometric evaluation; the ability of morphometrics to predict sperm cr...

  16. Robust Geometric Control of a Distillation Column

    DEFF Research Database (Denmark)

    Kymmel, Mogens; Andersen, Henrik Weisberg

    1987-01-01

    A frequency domain method, which makes it possible to adjust multivariable controllers with respect to both nominal performance and robustness, is presented. The basic idea in the approach is that the designer assigns objectives such as steady-state tracking, maximum resonance peaks, bandwidth, m...... is used to examine and improve geometric control of a binary distillation column....

  17. Robust topology optimization accounting for geometric imperfections

    DEFF Research Database (Denmark)

    Schevenels, M.; Jansen, M.; Lombaert, Geert

    2013-01-01

    performance. As a consequence, the actual structure may be far from optimal. In this paper, a robust approach to topology optimization is presented, taking into account two types of geometric imperfections: variations of (1) the crosssections and (2) the locations of structural elements. The first type...... of imperfections) and a vertical load carrying system (for the second type). © 2013 Taylor & Francis Group, London....

  18. Algebraic geometric codes with applications

    Institute of Scientific and Technical Information of China (English)

    CHEN Hao

    2007-01-01

    The theory of linear error-correcting codes from algebraic geomet-ric curves (algebraic geometric (AG) codes or geometric Goppa codes) has been well-developed since the work of Goppa and Tsfasman, Vladut, and Zink in 1981-1982. In this paper we introduce to readers some recent progress in algebraic geometric codes and their applications in quantum error-correcting codes, secure multi-party computation and the construction of good binary codes.

  19. MORPHOMETRIC ANALYSIS OF GLENOID FOSSA OF SCAPULA

    Directory of Open Access Journals (Sweden)

    Sangeeta

    2015-06-01

    Full Text Available The study was conducted on sixty scapulae obtained from the department of Anatomy, Government Medical College, Jammu. The shape of the glenoid cavity was observed in all the scapulae. It was inverted comma shaped, tear drop shaped, oval and round shaped. T he shape on the two sides was compared. Morphometry of the glenoid cavity was done and compared on right and left side. The dimensions of the glenoid fossa provide important information for designing and fitting of glenoid component for shoulder arthroplas ty. An understanding of variations of glenoid cavity is essential for evaluating pathological conditions like osseous Bankart lesions and osteochondral defects. INTRODUCTION: Shoulder arthroplasty is a common mode of treatment to treat shoulder pathologies like shoulder arthritis. Knowledge about the shape and morphological parameters is essential for success of shoulder arthroplasty as otherwise there would be loosening of the joint necessisitating the need for revision surgery. The articular surfaces for shoulder joint are the glenoid cavity (or fossa of scapula and head of humerus. The glenoid fossa is a shallow ovoid depression on the lateral angle of the scapula. It is also called as the glenoid cavity or the head of the scapula. There is variation in the shape of the glenoid fossa. The glenoid rim presents a small notch on its anterior and upper part . (1 The glenoid notch prevents the attachment of fibrocartilaginous glenoidal labrum to the glenoidal rim, which can be detach ed leading to Bankart, s les ion . (2 A knowledge of the shape and morphometry of glenoid fossa is essential for treat ing glenohumeral osteoarthritis . (3 Morphometric analysis of glenoid fossa is also essential when total shoulder prosthesis has to be used. It is also essential for eva luating Bankart lesion, osteochondral defects, shoulder instability etc. Thorough scanning of available literature revealed that there is dearth of literature regarding

  20. Morphometric analysis of sinkholes in a karst coastal area

    Science.gov (United States)

    Basso, A.; Bruno, E.; Parise, M.; Pepe, M.

    2012-04-01

    Salento, the southern portion of Apulia region (SE Italy) is a narrow and elongated peninsula in carbonate rocks, with prevailing low coastlines, locally interrupted by high rock cliffs. The long stretches of low coasts are marked by typical karst landforms consisting of collapse sinkholes. These are locally designated with the dialectal term "spunnulate" (deriving from the verb "spunnare", which means to break, to sink; PARISE et al., 2003). As observed in many other karst coastal settings worldwide (FORTH et al., 1999), development of sinkholes may be particularly severe along the coast, where both natural and anthropogenic processes contribute to accelerate the dissolution of carbonate rocks and subsidence processes, influencing the coastline evolution. Following a previous study, where the main features of sinkholes at Torre Castiglione (Taranto province) were investigated and described, and a preliminary susceptibility map produced (BRUNO et al., 2008), in the present paper we perform a detailed morphometric analysis on the sample of identified sinkholes. The main morphometric parameters generally used for sinkhole characterization have been considered in this study: shape of the sinkhole, azimuth and length of major and minimum axes, depth, elongation ratio, distance from the shorelines. Each of them is described, both as individual parameter and in conjunction with the others, in the attempt to identify the main factors controlling development of sinkholes in the area, and their evolution as well. As regards this latter aspect, beside simple morphometry of the sample of sinkholes at Torre Castiglione, we also focused our attention on the likely relationships existing between distribution and shape of the sinkholes and the tectonic discontinuities. The role played by discontinuities in controlling both distribution and evolution of sinkholes has been pointed out by several authors (WHITE & WHITE, 1987; DENIZMAN, 2003; FLOREA, 2005). To investigate the matter

  1. A new computerized morphometric analysis for peripheral nerve study.

    Science.gov (United States)

    Tobin, Chase A; Wang, Ziyi; Zhang, Lin-Ling; Agresti, Michael; Grewal, Prabhjot; Matloub, Hani S; Yan, Ji-Geng

    2014-02-01

    The commonly used methods to quantify axon numbers and mean area include manual and semiautomated procedures. The authors introduce a new fully automated method of morphometric analysis using ImageJ and Paint.net software to improve efficiency and accuracy. A total of six rat sciatic nerves were examined for their axon numbers and mean axon area by comparing the manual method or semiautomated MetaVue method with the new ImageJ method. It was observed that the number of axons for manual counting and ImageJ were 4,630 ± 403 and 4,779 ± 352, respectively, and the difference was not statistically significant (p > 0.5, t-test). The mean axon area measured was 13.44 ± 2.62 µm2 for MetaVue and 8.87 ± 0.78 µm2 for ImageJ, respectively, and the difference was statistically significant (p ImageJ were 0.32 and 0.087. The authors conclude that their new approach demonstrates improved convenience, time efficiency, accuracy, and less operator error or bias.

  2. Geometric Number Systems and Spinors

    CERN Document Server

    Sobczyk, Garret

    2015-01-01

    The real number system is geometrically extended to include three new anticommuting square roots of plus one, each such root representing the direction of a unit vector along the orthonormal coordinate axes of Euclidean 3-space. The resulting geometric (Clifford) algebra provides a geometric basis for the famous Pauli matrices which, in turn, proves the consistency of the rules of geometric algebra. The flexibility of the concept of geometric numbers opens the door to new understanding of the nature of space-time, and of Pauli and Dirac spinors as points on the Riemann sphere, including Lorentz boosts.

  3. Geometric analysis and PDEs

    CERN Document Server

    Ambrosetti, Antonio; Malchiodi, Andrea

    2009-01-01

    This volume contains lecture notes on some topics in geometric analysis, a growing mathematical subject which uses analytical techniques, mostly of partial differential equations, to treat problems in differential geometry and mathematical physics. The presentation of the material should be rather accessible to non-experts in the field, since the presentation is didactic in nature. The reader will be provided with a survey containing some of the most exciting topics in the field, with a series of techniques used to treat such problems.

  4. Robust Geometric Spanners

    CERN Document Server

    Bose, Prosenjit; Morin, Pat; Smid, Michiel

    2012-01-01

    Highly connected and yet sparse graphs (such as expanders or graphs of high treewidth) are fundamental, widely applicable and extensively studied combinatorial objects. We initiate the study of such highly connected graphs that are, in addition, geometric spanners. We define a property of spanners called robustness. Informally, when one removes a few vertices from a robust spanner, this harms only a small number of other vertices. We show that robust spanners must have a superlinear number of edges, even in one dimension. On the positive side, we give constructions, for any dimension, of robust spanners with a near-linear number of edges.

  5. Geometric Algebra Computing

    CERN Document Server

    Corrochano, Eduardo Bayro

    2010-01-01

    This book presents contributions from a global selection of experts in the field. This useful text offers new insights and solutions for the development of theorems, algorithms and advanced methods for real-time applications across a range of disciplines. Written in an accessible style, the discussion of all applications is enhanced by the inclusion of numerous examples, figures and experimental analysis. Features: provides a thorough discussion of several tasks for image processing, pattern recognition, computer vision, robotics and computer graphics using the geometric algebra framework; int

  6. Geometric phases in physics

    CERN Document Server

    Shapere, Alfred D

    1989-01-01

    During the last few years, considerable interest has been focused on the phase that waves accumulate when the equations governing the waves vary slowly. The recent flurry of activity was set off by a paper by Michael Berry, where it was found that the adiabatic evolution of energy eigenfunctions in quantum mechanics contains a phase of geometric origin (now known as 'Berry's phase') in addition to the usual dynamical phase derived from Schrödinger's equation. This observation, though basically elementary, seems to be quite profound. Phases with similar mathematical origins have been identified

  7. LUNGEOMETRY- GEOMETRICAL INVESTIGATION OF LUNGE

    Directory of Open Access Journals (Sweden)

    R.Vinodh Rajkumar

    2015-02-01

    Full Text Available Physiotherapists must learn the biomechanics of lunge in detail to clearly understand its significance in human life and implement effective training measures to overcome the limiting factors of proper lunge of their clientele. To understand the biomechanical value of every movement, interesting experimental learning methods must be employed to kindle the Physiotherapists to actively take part in research activities from the under-graduate level onwards. Lungeometry is a novel, simple and inexpensive experimental investigation of lunge, applying basic geometrical methods taking near normal lower limb length dimensions and rationale approaches into consideration. Lungeometry can give a foundation to learn other forms of lunges like forward lunge, weighted lunges, lateral lunges. This model of learning biomechanics of movements using fundamental geometry techniques is expected to strongly connect with any futuristic Physiotherapy curricular structure.

  8. Geometrical effective action and Wilsonian flows

    CERN Document Server

    Pawlowski, J M

    2003-01-01

    A gauge invariant flow equation is derived by applying a Wilsonian momentum cut-off to gauge invariant field variables. The construction makes use of the geometrical effective action for gauge theories in the Vilkovisky-DeWitt framework. The approach leads to modified Nielsen identities that pose non-trivial constraints on consistent truncations. We also evaluate the relation of the present approach to gauge fixed formulations as well as discussing possible applications.

  9. Spherical projections and liftings in geometric tomography

    DEFF Research Database (Denmark)

    Goodey, Paul; Kiderlen, Markus; Weil, Wolfgang

    2011-01-01

    We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies and to rad......We consider a variety of integral transforms arising in Geometric Tomography. It will be shown that these can be put into a common framework using spherical projection and lifting operators. These operators will be applied to support functions and surface area measures of convex bodies...... and to radial functions of star bodies. We then investigate averages of lifted projections and show that they correspond to self-adjoint intertwining operators. We obtain formulas for the eigenvalues of these operators and use them to ascertain circumstances under which tomographic measurements determine...... the original bodies. This approach via mean lifted projections leads us to some unexpected relationships between seemingly disparate geometric constructions....

  10. Duality orbits of non-geometric fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Dibitetto, G.; Roest, D. [Centre for Theoretical Physics, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Fernandez-Melgarejo, J.J. [Grupo de Fisica Teorica y Cosmologia, Dept. de Fisica, University of Murcia, Campus de Espinardo, 30100-Murcia (Spain); Marques, D. [Institut de Physique Theorique, CEA/ Saclay, 91191 Gif-sur-Yvette Cedex (France)

    2012-11-15

    Compactifications in duality covariant constructions such as generalised geometry and double field theory have proven to be suitable frameworks to reproduce gauged supergravities containing non-geometric fluxes. However, it is a priori unclear whether these approaches only provide a reformulation of old results, or also contain new physics. To address this question, we classify the T- and U-duality orbits of gaugings of (half-)maximal supergravities in dimensions seven and higher. It turns out that all orbits have a geometric supergravity origin in the maximal case, while there are non-geometric orbits in the half-maximal case. We show how the latter are obtained from compactifications of double field theory. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Understanding geometric algebra for electromagnetic theory

    CERN Document Server

    Arthur, John W

    2011-01-01

    "This book aims to disseminate geometric algebra as a straightforward mathematical tool set for working with and understanding classical electromagnetic theory. It's target readership is anyone who has some knowledge of electromagnetic theory, predominantly ordinary scientists and engineers who use it in the course of their work, or postgraduate students and senior undergraduates who are seeking to broaden their knowledge and increase their understanding of the subject. It is assumed that the reader is not a mathematical specialist and is neither familiar with geometric algebra or its application to electromagnetic theory. The modern approach, geometric algebra, is the mathematical tool set we should all have started out with and once the reader has a grasp of the subject, he or she cannot fail to realize that traditional vector analysis is really awkward and even misleading by comparison"--Provided by publisher.

  12. Morphometric study of third-instar larvae from five morphotypes of the Anastrepha fraterculus cryptic species complex (Diptera, Tephritidae).

    Science.gov (United States)

    Canal, Nelson A; Hernández-Ortiz, Vicente; Salas, Juan O Tigrero; Selivon, Denise

    2015-01-01

    The occurrence of cryptic species among economically important fruit flies strongly affects the development of management tactics for these pests. Tools for studying cryptic species not only facilitate evolutionary and systematic studies, but they also provide support for fruit fly management and quarantine activities. Previous studies have shown that the South American fruit fly, Anastrepha fraterculus, is a complex of cryptic species, but few studies have been performed on the morphology of its immature stages. An analysis of mandible shape and linear morphometric variability was applied to third-instar larvae of five morphotypes of the Anastrepha fraterculus complex: Mexican, Andean, Ecuadorian, Peruvian and Brazilian-1. Outline geometric morphometry was used to study the mouth hook shape and linear morphometry analysis was performed using 24 linear measurements of the body, cephalopharyngeal skeleton, mouth hook and hypopharyngeal sclerite. Different morphotypes were grouped accurately using canonical discriminant analyses of both the geometric and linear morphometry. The shape of the mandible differed among the morphotypes, and the anterior spiracle length, number of tubules of the anterior spiracle, length and height of the mouth hook and length of the cephalopharyngeal skeleton were the most significant variables in the linear morphometric analysis. Third-instar larvae provide useful characters for studies of cryptic species in the Anastrepha fraterculus complex.

  13. Morse Theory and the Geometric interpretation of NCCW Complexes

    CERN Document Server

    Milani, Vida; Rezaei, Ali Asghar

    2009-01-01

    The approach we present here is a modification of the Morse theory for unital C*-algebras.It helps us to study the geometry of the noncommutative CW complexes introduced in[1] and [2]. A geometric condition for a unital C*-algebra to admit a noncommutative CW complex decomposition is studied. Some examples to illustrate these geometric information in practice are given.

  14. Geometric Decision Tree

    CERN Document Server

    Manwani, Naresh

    2010-01-01

    In this paper we present a new algorithm for learning oblique decision trees. Most of the current decision tree algorithms rely on impurity measures to assess the goodness of hyperplanes at each node while learning a decision tree in a top-down fashion. These impurity measures do not properly capture the geometric structures in the data. Motivated by this, our algorithm uses a strategy to assess the hyperplanes in such a way that the geometric structure in the data is taken into account. At each node of the decision tree, we find the clustering hyperplanes for both the classes and use their angle bisectors as the split rule at that node. We show through empirical studies that this idea leads to small decision trees and better performance. We also present some analysis to show that the angle bisectors of clustering hyperplanes that we use as the split rules at each node, are solutions of an interesting optimization problem and hence argue that this is a principled method of learning a decision tree.

  15. Host-based identification is not supported by morphometrics in natural populations of Gyrodactylus salaris and G. thymalli (Platyhelminthes, Monogenea).

    Science.gov (United States)

    Olstad, K; Shinn, A P; Bachmann, L; Bakke, T A

    2007-12-01

    Gyrodactylus salaris is a serious pest of wild pre-smolt Atlantic salmon (Salmo salar) in Norway. The closely related G. thymalli, originally described from grayling (Thymallus thymallus), is assumed harmless to both grayling and salmon. The 2 species are difficult to distinguish using traditional, morphometric methods or molecular approaches. The aim of this study was to explore whether there is a consistent pattern of morphometrical variation between G. salaris and G. thymalli and to analyse the morphometric variation in the context of 'diagnostic realism' (in natural populations). Specimens from the type-material for the 2 species are also included. In total, 27 point-to-point measurements from the opisthaptoral hard parts were used and analysed by digital image processing and uni- and multivariate morphometry. All populations most closely resembled its respective type material, as expected from host species, with the exception of G. thymalli from the Norwegian river Trysilelva. We, therefore, did not find clear support in the morphometrical variation among G. salaris and G. thymalli for an a priori species delineation based on host. The present study also indicates an urgent need for more detailed knowledge on the influence of environmental factors on the phenotype of gyrodactylid populations.

  16. A phase-field approach to no-slip boundary conditions in dissipative particle dynamics and other particle models for fluid flow in geometrically complex confined systems.

    Science.gov (United States)

    Xu, Zhijie; Meakin, Paul

    2009-06-21

    Dissipative particle dynamics (DPD) is an effective mesoscopic particle model with a lower computational cost than molecular dynamics because of the soft potentials that it employs. However, the soft potential is not strong enough to prevent the DPD particles that are used to represent the fluid from penetrating solid boundaries represented by stationary DPD particles. A phase-field variable, phi(x,t), is used to indicate the phase at point x and time t, with a smooth transition from -1 (phase 1) to +1 (phase 2) across the interface. We describe an efficient implementation of no-slip boundary conditions in DPD models that combines solid-liquid particle-particle interactions with reflection at a sharp boundary located with subgrid scale accuracy using the phase field. This approach can be used for arbitrarily complex flow geometries and other similar particle models (such as smoothed particle hydrodynamics), and the validity of the model is demonstrated by DPD simulations of flow in confined systems with various geometries.

  17. Morphometric Analysis of Auxin-Mediated Development

    Science.gov (United States)

    Lewis, Daniel

    Auxin controls many aspects of plant development through its effects on growth. Its distribution is controlled by specific tissue and organ level polar transport streams. The responses to environmental cues such as gravity light, nutrient availability are largely controlled by coordinated regulation of distinct auxin transport streams. Many plant responses to the environment involve changes in shape. Much can be learned about the underlying processes controlling plant form if the response is measured with sufficient resolution. Computer-aided analysis of digital images or 'machine vision' can be used to greatly increase the speed and consistency of data from a morphometric study of plant form. Advances in image acquisition and analysis pioneered at UW-Madison have allowed unprecedented resolution of the growth and gravitropism of Arabidopsis. A reverse genetic analysis was used to determine if the MDR-like ABC transporters influence auxin distribution important for plant development and the response to environmental cues in Arabidopsis. Mutations in MDR1 (At3g28860) reduce acropetal auxin transport in the root. This is correlated with deviation from the vertical axis. Mutations in MDR4 (At2g47000) reduce basipetal auxin transport in the root. This is correlated with hypergravitropism. It was theorized that reduced transport whithin the elongation zone is responsible for the increased curvature. Flavanols were found to regulate gravitropism upstream of MDR4. The mdr1 mdr4 double mutant showed additive but not synergistic phenotypes, suggesting that the two auxin transport streams are more independent than interdependent. MDR proteins seem to enhance auxin transport in situations where PIN-type effux alone is insufficient.

  18. MORPHOMETRIC ANALYSES OF THE PARACENTRAL LOBE

    Directory of Open Access Journals (Sweden)

    Moacyr Oliveira Neto

    2014-03-01

    Full Text Available ntroduction:There are no studies that evaluate measurements of the distances between the grooves that delimit the Paracentral Lobule (PCL in the literature. This study seeks to contribute to the knowledge regarding the anatomy of the PCL, conducting an analysis of morphometric measurements in this region and its correlation with the paracentral sulcus, marginal branch of the cingulate and central sulcus. Methods:42 hemispheres were evaluated, 20 were right and 22 left. Using digital caliper Dc - 6 Western ®, measurements of the size of PCL in the sagittal axis and coronal axis were made, in addition to measures of the Central Sulcus to the Paracentral Sulcus (motor area and Central Sulcus to Marginal Branch of the Cingulate Sulcus (somesthetic area, comparing the prevalence of each of these lengths between hemispheres. Results:The average length between the Paracentral Sulcus and the Central Sulcus was 24.49 cm(14.2 to 38.6 cm in the right hemisphere and 25.50 cm(11.7 to 37.0 cm in the left. As between the Central Sulcus and the Marginal Branch of the Cingulate Sulcus was in average 10.03 cm(2.6 to 22.7 cm in the right and in the left PCL 9.17cm(2.6 to 22.7 cm. In the right hemisphere, 19 samples(86,4% presented greater motor area than somesthetic and, in the left hemisphere, 19 samples(95% had greater motor area. Conclusion:The motor area showed prevalence in relation to the sensory area in the analysis of the two hemispheres, while the comparison of other measures between the two hemispheres showed no significance.

  19. Morphometric analyses of the Paracentral Lobe.

    Directory of Open Access Journals (Sweden)

    Moacyr Oliveira Neto

    2014-03-01

    Full Text Available Introduction:There are no studies that evaluate measurements of the distances between the grooves that delimit the Paracentral Lobule (PCL in the literature. This study seeks to contribute to the knowledge regarding the anatomy of the PCL, conducting an analysis of morphometric measurements in this region and its correlation with the paracentral sulcus, marginal branch of the cingulate and central sulcus.Methods:42 hemispheres were evaluated, 20 were right and 22 left. Using digital caliper Dc - 6 Western ®, measurements of the size of PCL in the sagittal axis and coronal axis were made, in addition to measures of the Central Sulcus to the Paracentral Sulcus (motor area and Central Sulcus to Marginal Branch of the Cingulate Sulcus (somesthetic area, comparing the prevalence of each of these lengths between hemispheres.Results:The average length between the Paracentral Sulcus and the Central Sulcus was 24.49 cm(14.2 to 38.6 cm in the right hemisphere and 25.50 cm(11.7 to 37.0 cm in the left. As between the Central Sulcus and the Marginal Branch of the Cingulate Sulcus was in average 10.03 cm(2.6 to 22.7 cm in the right and in the left PCL 9.17cm(2.6 to 22.7 cm. In the right hemisphere, 19 samples(86,4% presented greater motor area than somesthetic and, in the left hemisphere, 19 samples(95%  had greater motor area.Conclusion:The motor area showed prevalence in relation to the sensory area in the analysis of the two hemispheres, while the comparison of other measures between the two hemispheres showed no significance.

  20. Morphometric analysis of llama (Lama glama) sperm head.

    Science.gov (United States)

    Casaretto, C; Lombardo, D M; Giuliano, S; Gambarotta, M; Carretero, M I; Miragaya, M H

    2012-05-01

    Llama production in Argentina has increased, as the international interest in breeding this type of animals has grown in the last years. Considering the great polymorphism that llama spermatozoa present at evaluation using light microscopy, the aim of this study was to objectively evaluate llama sperm head morphometry using digital morphometric analysis. Five ejaculates from each of eight males were obtained to evaluate morphometric parameters of 8000 sperm heads stained with Tinción 15(®). The following average results were obtained for each parameter: size parameters: area 20.09 μm(2), length 6.60 μm, width 4.14 μm, equivalent circle diameter 5.06 μm, curve length 5.79 μm and curve width 3.48 μm; boundary parameters: perimeter 18.54 μm and convex perimeter 17.34 μm; and shape parameters: roundness 1.28 and elongation 1.59. Morphometric parameters of sperm head were compared between ejaculates of the same male and between males. Significant differences between ejaculates of the same male were found for all parameters evaluated (P < 0.01). Significant differences between males were found for all morphometric parameters (P < 0.01) except for curve length, curve width and perimeter. The differences detected would indicate that there is not a single morphometric pattern for Lama glama sperm head, because parameter values cannot be standardised.

  1. Geometric Complexity Theory: Introduction

    CERN Document Server

    Sohoni, Ketan D Mulmuley Milind

    2007-01-01

    These are lectures notes for the introductory graduate courses on geometric complexity theory (GCT) in the computer science department, the university of Chicago. Part I consists of the lecture notes for the course given by the first author in the spring quarter, 2007. It gives introduction to the basic structure of GCT. Part II consists of the lecture notes for the course given by the second author in the spring quarter, 2003. It gives introduction to invariant theory with a view towards GCT. No background in algebraic geometry or representation theory is assumed. These lecture notes in conjunction with the article \\cite{GCTflip1}, which describes in detail the basic plan of GCT based on the principle called the flip, should provide a high level picture of GCT assuming familiarity with only basic notions of algebra, such as groups, rings, fields etc.

  2. The Geometric Transition Revisited

    CERN Document Server

    Gwyn, Rhiannon

    2007-01-01

    Our intention in this article is to review known facts and to summarise recent advances in the understanding of geometric transitions and the underlying open/closed duality in string theory. We aim to present a pedagogical discussion of the gauge theory underlying the Klebanov--Strassler model and review the Gopakumar--Vafa conjecture based on topological string theory. These models are also compared in the T-dual brane constructions. We then summarise a series of papers verifying both models on the supergravity level. An appendix provides extensive background material about conifold geometries. We pay special attention to their complex structures and re-evaluate the supersymmetry conditions on the background flux in constructions with fractional D3-branes on the singular (Klebanov--Strassler) and resolved (Pando Zayas--Tseytlin) conifolds. We agree with earlier results that only the singular solution allows a supersymmetric flux, but point out the importance of using the correct complex structure to reach th...

  3. Random geometric complexes

    CERN Document Server

    Kahle, Matthew

    2009-01-01

    We study the expected topological properties of Cech and Vietoris-Rips complexes built on randomly sampled points in R^d. These are, in some cases, analogues of known results for connectivity and component counts for random geometric graphs. However, an important difference in this setting is that homology is not monotone in the underlying parameter. In the sparse range, we compute the expectation and variance of the Betti numbers, and establish Central Limit Theorems and concentration of measure. In the dense range, we introduce Morse theoretic arguments to bound the expectation of the Betti numbers, which is the main technical contribution of this article. These results provide a detailed probabilistic picture to compare with the topological statistics of point cloud data.

  4. Geometrical Destabilization of Inflation

    Science.gov (United States)

    Renaux-Petel, Sébastien; Turzyński, Krzysztof

    2016-09-01

    We show the existence of a general mechanism by which heavy scalar fields can be destabilized during inflation, relying on the fact that the curvature of the field space manifold can dominate the stabilizing force from the potential and destabilize inflationary trajectories. We describe a simple and rather universal setup in which higher-order operators suppressed by a large energy scale trigger this instability. This phenomenon can prematurely end inflation, thereby leading to important observational consequences and sometimes excluding models that would otherwise perfectly fit the data. More generally, it modifies the interpretation of cosmological constraints in terms of fundamental physics. We also explain how the geometrical destabilization can lead to powerful selection criteria on the field space curvature of inflationary models.

  5. Geometric reasoning about assembly tools

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, R.H.

    1997-01-01

    Planning for assembly requires reasoning about various tools used by humans, robots, or other automation to manipulate, attach, and test parts and subassemblies. This paper presents a general framework to represent and reason about geometric accessibility issues for a wide variety of such assembly tools. Central to the framework is a use volume encoding a minimum space that must be free in an assembly state to apply a given tool, and placement constraints on where that volume must be placed relative to the parts on which the tool acts. Determining whether a tool can be applied in a given assembly state is then reduced to an instance of the FINDPLACE problem. In addition, the author presents more efficient methods to integrate the framework into assembly planning. For tools that are applied either before or after their target parts are mated, one method pre-processes a single tool application for all possible states of assembly of a product in polynomial time, reducing all later state-tool queries to evaluations of a simple expression. For tools applied after their target parts are mated, a complementary method guarantees polynomial-time assembly planning. The author presents a wide variety of tools that can be described adequately using the approach, and surveys tool catalogs to determine coverage of standard tools. Finally, the author describes an implementation of the approach in an assembly planning system and experiments with a library of over one hundred manual and robotic tools and several complex assemblies.

  6. Coordinate Geometric Generalization of the Spherometer and Cylindrometer

    CERN Document Server

    Khan, Sameen Ahmed

    2013-01-01

    Spherometer is an instrument widely used for measuring the radius of curvature of a spherical surface. Cylindrometer is a modified spherometer, which can measure the radii of both spherical and cylindrical surfaces. Both of these instruments are based on a geometric relation unique to circles and spheres, from Euclidean geometry. A more general understanding is obtained using coordinate geometry. The coordinate geometric approach also enables a generalization of the spherometer and cylindrometer to devices, which can handle aspherical surfaces. Here, we present the newly developed coordinate geometric approach and its applications.

  7. A Geometric Zero-One Law

    CERN Document Server

    Gilman, Robert H; Miasnikov, Alexei

    2007-01-01

    Each relational structure X has an associated Gaifman graph, which endows X with the properties of a graph. Suppose that X is infinite, connected and of bounded degree. A first-order sentence in the language of X is almost surely true (resp. a.s. false) for finite substructures of X if for every element x in X, the fraction of substructures of the ball of radius n around x which satisfy the sentence approaches 1 (resp. 0) as n approaches infinity. Suppose further that, for every finite substructure, X has a disjoint isomorphic substructure. Then every sentence is a.s. true or a.s. false for finite substructures of X. This is one form of the geometric zero-one law. We formulate it also in a form that does not mention the ambient infinite structure. In addition, we investigate various questions related to the geometric zero-one law.

  8. Geometric dynamical observables in rare gas crystals

    Energy Technology Data Exchange (ETDEWEB)

    Casetti, L. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Macchi, A. [Istituto Nazionale di Fisica della Materia (INFM), Unita di Firenze, Largo Enrico Fermi 2, 50125 Firenze (Italy)

    1997-03-01

    We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows us to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard methods of classical statistical mechanics, i.e., Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard-Jones crystal modeling solid xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations. {copyright} {ital 1997} {ital The American Physical Society}

  9. Geometric dynamical observables in rare gas crystals

    CERN Document Server

    Casetti, L; Casetti, Lapo; Macchi, Alessandro

    1996-01-01

    We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard mehods of classical statistical mechanics, i.e. Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard Jones crystal modeling solid Xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations.

  10. Missing data estimation in morphometrics: how much is too much?

    Science.gov (United States)

    Clavel, Julien; Merceron, Gildas; Escarguel, Gilles

    2014-03-01

    Fossil-based estimates of diversity and evolutionary dynamics mainly rely on the study of morphological variation. Unfortunately, organism remains are often altered by post-mortem taphonomic processes such as weathering or distortion. Such a loss of information often prevents quantitative multivariate description and statistically-controlled comparisons of extinct species based on morphometric data. A common way to deal with missing data involves imputation methods that directly fill the missing cases with model estimates. Over the last years, several empirically-determined thresholds for the maximum acceptable proportion of missing values have been proposed in the literature, whereas other studies showed that this limit actually depends on various properties of the study data set and of the selected imputation method, and is by no way generalizable. We evaluate the relative performances of seven multiple imputation (MI) techniques through a simulation-based analysis under three distinct patterns of missing data distribution. Overall, Fully Conditional Specification and Expectation-Maximization algorithms provide the best compromises between imputation accuracy and coverage probability. MI techniques appear remarkably robust to the violation of basic assumptions such as the occurrence of taxonomically or anatomically biased patterns of missing data distribution, making differences in simulation results between the three patterns of missing data distribution much smaller than differences between the individual MI techniques. Based on these results, rather than proposing a new (set of) threshold value(s), we develop an approach combining the use of MIs with procrustean superimposition of principal component analysis results, in order to directly visualize the effect of individual missing data imputation on an ordinated space. We provide an R function for users to implement the proposed procedure.

  11. Harmonic and geometric analysis

    CERN Document Server

    Citti, Giovanna; Pérez, Carlos; Sarti, Alessandro; Zhong, Xiao

    2015-01-01

    This book presents an expanded version of four series of lectures delivered by the authors at the CRM. Harmonic analysis, understood in a broad sense, has a very wide interplay with partial differential equations and in particular with the theory of quasiconformal mappings and its applications. Some areas in which real analysis has been extremely influential are PDE's and geometric analysis. Their foundations and subsequent developments made extensive use of the Calderón–Zygmund theory, especially the Lp inequalities for Calderón–Zygmund operators (Beurling transform and Riesz transform, among others) and the theory of Muckenhoupt weights.  The first chapter is an application of harmonic analysis and the Heisenberg group to understanding human vision, while the second and third chapters cover some of the main topics on linear and multilinear harmonic analysis. The last serves as a comprehensive introduction to a deep result from De Giorgi, Moser and Nash on the regularity of elliptic partial differen...

  12. Morphometric and hydraulic geometry assessment of a gully in SW Spain

    Science.gov (United States)

    Caraballo-Arias, N. A.; Conoscenti, C.; Di Stefano, C.; Ferro, V.; Gómez-Gutiérrez, A.

    2016-12-01

    Gully erosion represents one of the most significant types of land degradation in the Mediterranean areas, giving place to important on- and off-site effects. In this paper, a second-order gully located in SW Spain is analyzed. Along the gully, 28 cross-sections were established and measured with a Leica TCRM1102 laser total station, approximately every 6 months from 2001 to 2007. The sections were located at variable distance, placing them in areas where active erosion was evident. In total, 13 field measurements were carried out, and the geometric characteristics of 28 cross-sections were obtained. Morphometric analyses were carried out in both the main gully and a tributary reach by applying an empirical relationship between channel length and eroded volume. Morphometric variables of the gully sections were combined into two dimensionless groups, and a morphological similarity between different linear erosion landforms (rills, ephemeral and permanent gullies) was obtained. Then, the coefficient of variation of the calculated volumes was used to compare the instability between the main gully and the tributary reach. Finally, the hydraulic geometry of the gully was assessed by calibrating three empirical power equations, which relate bankfull discharge with mean flow velocity, cross-sectional depth and width. The hydraulic characterization of the main gully and the tributary reach was investigated for each field survey and a different behavior was detected. The hydraulic analysis also demonstrated that higher values of discharge provide better predictions of flow velocity; the size of the main and tributary gullies affects the discharge-width relationship; and that gully depth is the variable which can be predicted with the highest accuracy.

  13. A new geometrical approach to void statistics

    CERN Document Server

    Werner, M C

    2014-01-01

    Modelling cosmic voids as spheres in Euclidean space, the notion of a de-Sitter configuration space is introduced. It is shown that a uniform distribution over this configuration space yields a power-law approximating the void size distribution in an intermediate range of volumes, as well as an estimate for the fractal dimension of the large scale structure.

  14. Geometric approach to Ending Lamination Conjecture

    OpenAIRE

    Soma, Teruhiko

    2008-01-01

    We present a new proof of the bi-Lipschitz model theorem, which occupies the main part of the Ending Lamination Conjecture proved by Minsky and Brock-Canary-Minsky. Our proof is done by using techniques of standard hyperbolic geometry as much as possible.

  15. A Geometric Approach to Matrix Ordering

    CERN Document Server

    Auer, B O Fagginger

    2011-01-01

    We present a recursive way to partition hypergraphs which creates and exploits hypergraph geometry and is suitable for many-core parallel architectures. Such partitionings are then used to bring sparse matrices in a recursive Bordered Block Diagonal form (for processor-oblivious parallel LU decomposition) or recursive Separated Block Diagonal form (for cache-oblivious sparse matrix-vector multiplication). We show that the quality of the obtained partitionings and orderings is competitive by comparing obtained fill-in for LU decomposition with SuperLU (with better results for 8 of the 28 test matrices) and comparing cut sizes for sparse matrix-vector multiplication with Mondriaan (with better results for 4 of the 12 test matrices). The main advantage of the new method is its speed: it is on average 21.6 times faster than Mondriaan.

  16. Geometric approach to condensates in holographic QCD

    CERN Document Server

    Hirn, J; Sanz, V; Hirn, Johannes; Rius, Nuria; Sanz, Veronica

    2006-01-01

    An SU(Nf)xSU(Nf) Yang-Mills theory on an extra-dimensional interval is considered, with appropriate symmetry-breaking boundary conditions on the IR brane. UV-brane to UV-brane correlators at high energies are compared with the OPE of two-point functions of QCD quark currents. Condensates correspond to departure from AdS of the (different) metrics felt by vector and axial combinations, away from the UV brane. Their effect on hadronic observables is studied: the extracted condensates agree with the signs and orders of magnitude expected from QCD.

  17. Oscillator Phase Noise: A Geometrical Approach

    DEFF Research Database (Denmark)

    Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens

    2009-01-01

    We construct a coordinate-independent description of oscillator linear response through a decomposition scheme derived independently of any Floquet theoretic results. Trading matrix algebra for a simpler graphical methodology, the text will present the reader with an opportunity to gain an intuit...... an intuitive understanding of the well-known phase noise macromodel. The topics discussed in this paper include the following: orthogonal decompositions, AM–PM conversion, and nonhyperbolic oscillator noise response....

  18. In Defence of Geometrical Algebra

    OpenAIRE

    Blasjo, V.N.E.

    2016-01-01

    The geometrical algebra hypothesis was once the received interpretation of Greek mathematics. In recent decades, however, it has become anathema to many. I give a critical review of all arguments against it and offer a consistent rebuttal case against the modern consensus. Consequently, I find that the geometrical algebra interpretation should be reinstated as a viable historical hypothesis.

  19. Homological Type of Geometric Transitions

    CERN Document Server

    Rossi, Michele

    2010-01-01

    The present paper gives an account and quantifies the change in topology induced by small and type II geometric transitions, by introducing the notion of the \\emph{homological type} of a geometric transition. The obtained results agree with, and go further than, most results and estimates, given to date by several authors, both in mathematical and physical literature.

  20. Geometric Mechanics of Periodic Pleated Origami

    CERN Document Server

    Wei, Zhiyan; Dudte, Levi; Liang, Haiyi; Mahadevan, L

    2012-01-01

    Origami is the archetype of a structural material with unusual mechanical properties that arise almost exclusively from the geometry of its constituent folds and forms the basis for mechanical metamaterials with an extreme deformation response. Here we consider a simple periodically folded structure Miura-ori, which is composed of identical unit cells of mountain and valley folds with four-coordinated ridges, de?fined completely by 2 angles and 2 lengths. We use the geometrical properties of a Miura-ori plate to characterize its elastic response to planar and non-planar piece- wise isometric deformations and calculate the two-dimensional stretching and bending response of a Miura-ori sheet, and show that the in-plane and out-of-plane Poisson's ratios are equal in magnitude, but opposite in sign. Our geometric approach also allows us to solve the inverse design problem of determining the geometric parameters that achieve the optimal geometric and mechanical response of such structures.

  1. The geometrical structure of quantum theory as a natural generalization of information geometry

    Energy Technology Data Exchange (ETDEWEB)

    Reginatto, Marcel [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    2015-01-13

    Quantum mechanics has a rich geometrical structure which allows for a geometrical formulation of the theory. This formalism was introduced by Kibble and later developed by a number of other authors. The usual approach has been to start from the standard description of quantum mechanics and identify the relevant geometrical features that can be used for the reformulation of the theory. Here this procedure is inverted: the geometrical structure of quantum theory is derived from information geometry, a geometrical structure that may be considered more fundamental, and the Hilbert space of the standard formulation of quantum mechanics is constructed using geometrical quantities. This suggests that quantum theory has its roots in information geometry.

  2. Transmuted Complementary Weibull Geometric Distribution

    Directory of Open Access Journals (Sweden)

    Ahmed Z. A…fify

    2014-12-01

    Full Text Available This paper provides a new generalization of the complementary Weibull geometric distribution that introduced by Tojeiro et al. (2014, using the quadratic rank transmutation map studied by Shaw and Buckley (2007. The new distribution is referred to as transmuted complementary Weibull geometric distribution (TCWGD. The TCWG distribution includes as special cases the complementary Weibull geometric distribution (CWGD, complementary exponential geometric distribution(CEGD,Weibull distribution (WD and exponential distribution (ED. Various structural properties of the new distribution including moments, quantiles, moment generating function and RØnyi entropy of the subject distribution are derived. We proposed the method of maximum likelihood for estimating the model parameters and obtain the observed information matrix. A real data set are used to compare the ‡exibility of the transmuted version versus the complementary Weibull geometric distribution.

  3. Geometric phase and Pancharatnam phase induced by light wave polarization

    CERN Document Server

    Lages, J; Vigoureux, J -M

    2013-01-01

    We use the quantum kinematic approach to revisit geometric phases associated with polarizing processes of a monochromatic light wave. We give the expressions of geometric phases for any, unitary or non-unitary, cyclic or non-cyclic transformations of the light wave state. Contrarily to the usually considered case of absorbing polarizers, we found that a light wave passing through a polarizer may acquire in general a non zero geometric phase. This geometric phase exists despite the fact that initial and final polarization states are in phase according to the Pancharatnam criterion and can not be measured using interferometric superposition. Consequently, there is a difference between the Pancharatnam phase and the complete geometric phase acquired by a light wave passing through a polarizer. We illustrate our work with the particular example of total reflection based polarizers.

  4. Geometric control theory and sub-Riemannian geometry

    CERN Document Server

    Boscain, Ugo; Gauthier, Jean-Paul; Sarychev, Andrey; Sigalotti, Mario

    2014-01-01

    This volume presents recent advances in the interaction between Geometric Control Theory and sub-Riemannian geometry. On the one hand, Geometric Control Theory used the differential geometric and Lie algebraic language for studying controllability, motion planning, stabilizability and optimality for control systems. The geometric approach turned out to be fruitful in applications to robotics, vision modeling, mathematical physics etc. On the other hand, Riemannian geometry and its generalizations, such as  sub-Riemannian, Finslerian  geometry etc., have been actively adopting methods developed in the scope of geometric control. Application of these methods  has led to important results regarding geometry of sub-Riemannian spaces, regularity of sub-Riemannian distances, properties of the group  of diffeomorphisms of sub-Riemannian manifolds, local geometry and equivalence of distributions and sub-Riemannian structures, regularity of the Hausdorff volume.

  5. Geometrical method of decoupling

    Science.gov (United States)

    Baumgarten, C.

    2012-12-01

    The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances) the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E→, B→, and P→, which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of) transformations must be symplectic and hence canonical. When used iteratively, the decoupling

  6. Morphometric Analysis of Mandibular Growth in Skeletal Class III Malocclusion

    Directory of Open Access Journals (Sweden)

    Jenny Zwei-Chieng Chang

    2006-01-01

    Conclusion: We conclude that thin-plate spline analysis and the finite element morphometric method are efficient for the localization and quantification of size and shape changes that occur during mandibular growth. Plots of maximum and minimum principal directions can provide useful information about the trends of growth changes.

  7. Morphometric studies on a part of Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Kodagali, V.N.

    Morphometric and slope angle studies carried out on a part of Indian Ocean Basin have shown that gentle slope angle ranges dominate, 92% of the area represented by 0-3 degrees slopes. Young's hypothesis of log-normal distribution of slope angle...

  8. Catchment delineation and morphometric analysis using geographical information system.

    Science.gov (United States)

    Kumar, Manoj; Kumar, Rohitashw; Singh, P K; Singh, Manjeet; Yadav, K K; Mittal, H K

    2015-01-01

    The geographical information system (GIS) has emerged as an efficient tool in delineation of drainage patterns of watershed planning and management. The morphometric parameters of basins can address linear, areal and relief aspects. The study deals with the integrated watershed management of Baliya micro-watersheds, located in the Udaipur district of Rajasthan, India. Morphometric analysis in hydrological investigation is an important aspect and it is inevitable in the development and management of drainage basins. The determination of linear, areal and relief parameters indicate fairly good significance. The low value of the bifurcation ratio of 4.19 revealed that the drainage pattern has not been distorted by structural disturbance. The high value of the elongation ratio (0.68) compared to the circulatory ratio (0.27) indicates an elongated shape of the watershed. The high value of drainage density (5.39 km/km(2)) and stream frequency (12.32) shows that the region has impermeable subsoil material under poor vegetative cover with a low relief factor. The morphometric parameters of relief ratio (0.041) and relative relief (0.99%) show that the watershed can be treated using GIS techniques to determine the morphometric presence of dendritic drainage pattern, with a view to selecting the soil and water conservation measures and water harvesting.

  9. Morphometric Evaluation of Preeclamptic Placenta Using Light Microscopic Images

    Directory of Open Access Journals (Sweden)

    Rashmi Mukherjee

    2014-01-01

    Full Text Available Deficient trophoblast invasion and anomalies in placental development generally lead to preeclampsia (PE but the inter-relationship between placental function and morphology in PE still remains unknown. The aim of this study was to evaluate the morphometric features of placental villi and capillaries in preeclamptic and normal placentae. The study included light microscopic images of placental tissue sections of 40 preeclamptic and 35 normotensive pregnant women. Preprocessing and segmentation of these images were performed to characterize the villi and capillaries. Fisher’s linear discriminant analysis (FLDA, hierarchical cluster analysis (HCA, and principal component analysis (PCA were applied to identify the most significant placental (morphometric features from microscopic images. A total of 10 morphometric features were extracted, of which the villous parameters were significantly altered in PE. FLDA identified 5 highly significant morphometric features (>90% overall discrimination accuracy. Two large subclusters were clearly visible in HCA based dendrogram. PCA returned three most significant principal components cumulatively explaining 98.4% of the total variance based on these 5 significant features. Hence, quantitative microscopic evaluation revealed that placental morphometry plays an important role in characterizing PE, where the villous is the major component that is affected.

  10. Morphometric study of Euchiton traversii complex (Gnaphalieae: Asteraceae)

    NARCIS (Netherlands)

    Flann, C.M.; Breitwieser, I.; Ward, J.M.; Walsh, N.G.; Ladiges, P.Y.

    2008-01-01

    A morphometric study was undertaken into alpine and subalpine species of Euchiton Cass. (Gnaphalieae: Asteraceae) in the Euchiton traversii species complex in south-eastern Australia and New Zealand. Phenetic analysis of both field-collected and herbarium specimens resolved the following six taxa in

  11. 拟似然非线性模型的某些渐近推断:几何方法%SOME ASYMPTOTIC INFERENCE IN QUASI-LIKELIHOOD NONLINEAR MODELS:A GEOMETRIC APPROACH

    Institute of Scientific and Technical Information of China (English)

    韦博成; 唐年胜; 王学仁

    2000-01-01

    A modified Bates and Watts geometric framework is proposed for quasi-likelihood nonlinear models in Euclidean inner product space.Based on the modified geometric framework,some asymptotic inference in terms of curvatures for quasi-likelihood nonlinear models is studied.Several previous results for nonlinear regression models and exponential family nonlinear models etc.are extended to quasi-likelihood nonlinear models.

  12. Age characteristic of morphometric parameters of an orbit in adults

    Directory of Open Access Journals (Sweden)

    Dubyna S.O.

    2015-03-01

    Full Text Available Background. The knowledge of a morphometric characteristics of an orbit are important in planning of surgical interventions after craniofacial injuries and a number of ophthalmologic and oncological diseases. Objective. To determine the standard morphometric parameters of an orbit in humans of different age groups. Methods. Research was performed in Donetsk diagnostic center with the use of computer tomography-scans. 96 people aged from 21 to 74 years took part in the research with their consent; 32 people – the first period of mature age (men – 22-35 years, women – 21-35 years; 32 people – the second period of mature age (men – 36-60 years, women – 36-55 years; 32 people –aged group (men – 61-74 years, women – 56-74 years – without pathologies of a craniofacial zone. Orbit length, its depth, angle between medial and lateral walls, width and height of an orbital entrance, inclination angle were measured. Results. Significant asymmetry in values of the length of the lower orbital wall in the first period of mature age was revealed. It affects the value of this parameter as a morphometric standard during surgical intervention, and justifies the measurement at least in two planes: frontal and axial. Conclusion. It was established that there are no reliable differences between morphometric parameters of an orbit in persons of various age groups, except the depth of an orbit and length of its lower wall in the second period of the mature age. Citation: Dubyna SO, Yabluchansky MI. [Age characteristic of morphometric parameters of an orbit in adults]. Morphologia. 2015;9(1:29-33. Ukrainian.

  13. MORPHOLOGICAL FEATURES AND MORPHOMETRIC PARAMETERS OF HUMAN FETAL THYMUS GLANDS

    Directory of Open Access Journals (Sweden)

    S. Havila Hasini

    2014-03-01

    Full Text Available Introduction: Thymus is one of the central lymphoid organs. It plays an important role in the differentiation, selection and maturation of T-lymphocytes. In the recent years morphology and morphometry of the thymus gland in the newborn is gaining significance as it demonstrates great variability between individual infants and in the same infant at different times. Materials and methods: In the present study 45 thymus specimens from aborted human fetuses of 16 to 40 weeks gestational age and both sexes were studied by autopsy for morphological and morphometric features. The morphometric parameters were measured using pachymeter. Results: The thymus gland was located in the superior mediastinum. 60% (27/45 specimens showed cervical extensions. Brachiocephalic vein anterior to thymus was observed in 3 cases which is an important anomaly to be observed in thymectomy procedure. Thymuses were greyish pink to greyish brown in colour. Variations were also observed in the number of lobes of glands in which one is single lobed, most of the glands are bilobed and few are trilobed. There is progressive increase in all morphometric dimensions of the thymus in relation to gestational age. Most of the specimens were less than 4cm in length. Half of the specimens were below 2cm in width and other half were 2.0 to 5.0 cm in width. For 90% of the specimens thickness of the organ was less than 0.5cm. The thymus gland was 0.2% of fetal body weight. Conclusion: The morphological observations of thymus gland shows great variations which has to be considered in thymectomy. In addition to anthropometric parameters of fetus, morphometric parameters of thymus glands present significant relation to the gestational age of fetuses. It is possible to determine the thymic morphometric parameters in relation to gestational age.

  14. Morphometric Analysis of a semi-arid region using GIS

    Directory of Open Access Journals (Sweden)

    Rohit Kumar Arya

    2017-06-01

    Full Text Available In the present study an attempt has been made to study the morphometric parameters and drainage properties of a watershed of semi-arid (khad region located at Hoshiarpur district of Punjab (India. Morphometric analysis has been carried out on the watershed of 174.385 km2 area using ESRI Arc GIS 10.0 software and CartoSAT-1 DEM data of spatial resolution 2.5 m obtained from NRSC (National Remote Sensing Center, Hyderabad for evaluating various morphometric parameters. On the basis of linear, areal and relief aspects various morphometric parameters were evaluated using Arc GIS 10.0 software. Hydrology tool under Spatial analyst tool in ArcGIS10.0 has been used for generating the watershed boundary, flow accumulation, drainage network and stream order map. Area and the perimeter have been calculated using ArcGIS 10.0 and it comes out to be 174.385 Km2 and 77.539 km respectively. Drainage map of the study area shows dendritic to sub-dendritic drainage pattern. The study reveals that the stream number decreases with the increase in the stream order, the mean bifurcation ratio of the watershed is 4.35 which means that the watershed falls under normal basin category, the elongation ratio of the watershed is 0.604 which indicates that it is less elongated, the circularity ratio of the watershed is 0.365 indicating its elongation and highly permeable homogeneous materials. The present study shows the competency of remotely sensed satellite imagery coupled with GIS for morphometric analysis of a particular region and is useful for the watershed management, identification of critical zones and for implementing various soil and water conservation practices in that region or watershed.

  15. Geometrical method of decoupling

    Directory of Open Access Journals (Sweden)

    C. Baumgarten

    2012-12-01

    Full Text Available The computation of tunes and matched beam distributions are essential steps in the analysis of circular accelerators. If certain symmetries—like midplane symmetry—are present, then it is possible to treat the betatron motion in the horizontal, the vertical plane, and (under certain circumstances the longitudinal motion separately using the well-known Courant-Snyder theory, or to apply transformations that have been described previously as, for instance, the method of Teng and Edwards. In a preceding paper, it has been shown that this method requires a modification for the treatment of isochronous cyclotrons with non-negligible space charge forces. Unfortunately, the modification was numerically not as stable as desired and it was still unclear, if the extension would work for all conceivable cases. Hence, a systematic derivation of a more general treatment seemed advisable. In a second paper, the author suggested the use of real Dirac matrices as basic tools for coupled linear optics and gave a straightforward recipe to decouple positive definite Hamiltonians with imaginary eigenvalues. In this article this method is generalized and simplified in order to formulate a straightforward method to decouple Hamiltonian matrices with eigenvalues on the real and the imaginary axis. The decoupling of symplectic matrices which are exponentials of such Hamiltonian matrices can be deduced from this in a few steps. It is shown that this algebraic decoupling is closely related to a geometric “decoupling” by the orthogonalization of the vectors E[over →], B[over →], and P[over →], which were introduced with the so-called “electromechanical equivalence.” A mathematical analysis of the problem can be traced down to the task of finding a structure-preserving block diagonalization of symplectic or Hamiltonian matrices. Structure preservation means in this context that the (sequence of transformations must be symplectic and hence canonical. When

  16. Geometric Computing for Freeform Architecture

    KAUST Repository

    Wallner, J.

    2011-06-03

    Geometric computing has recently found a new field of applications, namely the various geometric problems which lie at the heart of rationalization and construction-aware design processes of freeform architecture. We report on our work in this area, dealing with meshes with planar faces and meshes which allow multilayer constructions (which is related to discrete surfaces and their curvatures), triangles meshes with circle-packing properties (which is related to conformal uniformization), and with the paneling problem. We emphasize the combination of numerical optimization and geometric knowledge.

  17. Geometric inequalities for black holes

    Energy Technology Data Exchange (ETDEWEB)

    Dain, Sergio [Universidad Nacional de Cordoba (Argentina)

    2013-07-01

    Full text: A geometric inequality in General Relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities, which are valid in the dynamical and strong field regime, play an important role in the characterization of the gravitational collapse. They are closed related with the cosmic censorship conjecture. In this talk I will review recent results in this subject. (author)

  18. Scale effect and geometric shapes of grains

    Institute of Scientific and Technical Information of China (English)

    GUO Hui; GUO Xing-ming

    2007-01-01

    The rule-of-mixture approach has become one of the widely spread ways to investigate the mechanical properties of nano-materials and nano-structures, and it is very important for the simulation results to exactly compute phase volume fractions. The nanocrystalline (NC) materials are treated as three-phase composites consisting of grain core phase, grain boundary (GB) phase and triple junction phase, and a two-dimensional three-phase mixture regular polygon model is established to investigate the scale effect of mechanical properties of NC materials due to the geometrical polyhedron characteristics of crystal grain. For different multi-sided geometrical shapes of grains, the corresponding regular polygon model is adopted to obtain more precise phase volume fractions and exactly predict the mechanical properties of NC materials.

  19. Langlands Program, Trace Formulas, and their Geometrization

    CERN Document Server

    Frenkel, Edward

    2012-01-01

    The Langlands Program relates Galois representations and automorphic representations of reductive algebraic groups. The trace formula is a powerful tool in the study of this connection and the Langlands Functoriality Conjecture. After giving an introduction to the Langlands Program and its geometric version, which applies to curves over finite fields and over the complex field, I give a survey of my recent joint work with Robert Langlands and Ngo Bao Chau (arXiv:1003.4578 and arXiv:1004.5323) on a new approach to proving the Functoriality Conjecture using the trace formulas, and on the geometrization of the trace formulas. In particular, I discuss the connection of the latter to the categorification of the Langlands correspondence.

  20. Geometrical vs wave optics under gravitational waves

    CERN Document Server

    Angélil, Raymond

    2015-01-01

    We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely null geodesics and Maxwell's equations, or, geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics, rather than solving Maxwell's equations directly for the fields, as in most previous approaches, we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic...

  1. Topological minimally entangled states via geometric measure

    Science.gov (United States)

    Buerschaper, Oliver; García-Saez, Artur; Orús, Román; Wei, Tzu-Chieh

    2014-11-01

    Here we show how the Minimally Entangled States (MES) of a 2d system with topological order can be identified using the geometric measure of entanglement. We show this by minimizing this measure for the doubled semion, doubled Fibonacci and toric code models on a torus with non-trivial topological partitions. Our calculations are done either quasi-exactly for small system sizes, or using the tensor network approach in Orús et al (arXiv:1406.0585) for large sizes. As a byproduct of our methods, we see that the minimisation of the geometric entanglement can also determine the number of Abelian quasiparticle excitations in a given model. The results in this paper provide a very efficient and accurate way of extracting the full topological information of a 2d quantum lattice model from the multipartite entanglement structure of its ground states.

  2. CCH-based geometric algorithms for SVM and applications

    Institute of Scientific and Technical Information of China (English)

    Xin-jun PENG; Yi-fei WANG

    2009-01-01

    The support vector machine (SVM) is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull (CCH) with a mathematical framework is introduced to solve SVM classification problems. Compared with the reduced convex hull (RCH), CCH preserves the shape of geometric solids for data sets; meanwhile, it is easy to give the necessary and sufficient condition for determining its extreme points. As practical applications of CCH, spare and probabilistic speed-up geometric algorithms are developed. Results of numerical experiments show that the proposed algorithms can reduce kernel calculations and display nice performances.

  3. Geometric structure of gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Mangiarotti, L.; Modugno, M.

    1985-06-01

    In the framework of the adjoint forms over the jet spaces of connections and using a canonical jet shift differential, we give a geometrical interpretation of the Yang--Mills equations both in a direct and Lagrangian formulation.

  4. Geometrical product specifications. Datums and coordinate systems

    Science.gov (United States)

    Glukhov, V. I.; Ivleva, I. A.; Zlatkina, O. Y.

    2017-06-01

    The work is devoted to the relevant topic such as the technical products quality improvement due to the geometrical specifications accuracy. The research purpose is to ensure the quality indicators on the basis of the systematic approach to the values normalization and geometrical specifications accuracy in the workpiece coordinate systems in the process of design. To achieve the goal two tasks are completed such as the datum features classification according to the number of linear and angular freedom degrees constraints, called the datums informativeness, and the rectangular coordinate systems identification, materialized by workpiece datums sets. The datum features informativeness characterizes the datums functional purpose to limit product workpiece linear and angular degrees of freedom. The datum features informativeness numerically coincides with the kinematic pairs classes and couplings in mechanics. The datum features informativeness identifies the coordinate system without the location redundancy. Each coordinate plane of a rectangular coordinate system has different informativeness 3 + 2 + 1. Each coordinate axis also has different informativeness 4+2+Θ (zero). It is possible to establish the associated workpiece position with three linear and three angular coordinates relative to two axes with the informativeness 4 and 2. is higher, the more informativeness of the coordinate axis or a coordinate plane is, the higher is the linear and angular coordinates accuracy, the coordinate being plotted along the coordinate axis or plane. The systematic approach to the geometrical products specifications positioning in coordinate systems is the scientific basis for a natural transition to the functional dimensions of features position - coordinating dimensions and the size of the features form - feature dimensions of two measures: linear and angular ones. The products technical quality improving is possible due to the coordinate systems introduction materialized by

  5. Determining Geometric Accuracy in Turning

    Institute of Scientific and Technical Information of China (English)

    Kwong; Chi; Kit; A; Geddam

    2002-01-01

    Mechanical components machined to high levels of ac cu racy are vital to achieve various functional requirements in engineering product s. In particular, the geometric accuracy of turned components play an important role in determining the form, fit and function of mechanical assembly requiremen ts. The geometric accuracy requirements of turned components are usually specifi ed in terms of roundness, straightness, cylindricity and concentricity. In pract ice, the accuracy specifications achievable are infl...

  6. The Geometric Gravitational Internal Problem

    CERN Document Server

    González-Martin, G R

    2000-01-01

    In a geometric unified theory there is an energy momentum equation, apart from the field equations and equations of motion. The general relativity Einstein equation with cosmological constant follows from this energy momentum equation for empty space. For non empty space we obtain a generalized Einstein equation, relating the Einstein tensor to a geometric stress energy tensor. The matching exterior solution is in agreement with the standard relativity tests. Furthermore, there is a Newtonian limit where we obtain Poisson's equation.

  7. Geometric symmetries in light nuclei

    CERN Document Server

    Bijker, Roelof

    2016-01-01

    The algebraic cluster model is is applied to study cluster states in the nuclei 12C and 16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the alpha-particles, i.e. an equilateral triangle for 12C, and a regular tetrahedron for 16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of alpha-particles.

  8. Toward Geometric Visual Servoing

    Science.gov (United States)

    2002-09-26

    IEEE Transactions on Robotics and Automation, 17(4):507–515, 2001. [3] Noah Cowan...and Robert Mahony. Visual servong of an under-actuated dynamic rigid-body system: An image-based approach. IEEE Transactions on Robotics and...Automation, 18(2):187–198, April 2002. [7] S. Hutchinson, G. D. Hager, and P. I. Corke. A tutorial on visual servo control. IEEE Transactions on Robotics

  9. Non-critical string, Liouville theory and geometric bootstrap hypothesis

    CERN Document Server

    Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew

    2003-01-01

    Basing on the standard construction of critical string amplitudes we analyze properties of the longitudinal sector of the non-critical Nambu-Goto string. We demonstrate that it cannot be described by standard (in the sense of BPZ) conformal field theory. As an alternative we propose a new version of the geometric approach to Liouville theory and formulate its basic consistency condition - the geometric bootstrap equation.

  10. Geometric and spectral consequences of curvature bounds on tessellations

    OpenAIRE

    Keller, Matthias

    2016-01-01

    This is a chapter of a forthcoming Lecture Notes in Mathematics "Modern Approaches to Discrete Curvature" edited by L. Najman and P. Romon. It provides a survey on geometric and spectral consequences of curvature bounds. The geometric setting are tessellations of surfaces with finite and vanishing genus. We consider a curvature arising as an angular defect. Several of the results presented here have analogues in Riemannian geometry. In some cases one can go even beyond the Riemannian results ...

  11. Alternative proofs for Kocik's Geometric Diagram for Relativistic Velocity Addition

    CERN Document Server

    Sasane, Amol

    2015-01-01

    A geometric construction for the Poincare formula for relativistic addition of velocities in one dimension was given by Jerzy Kocik in "Geometric Diagram for Relativistic Addition of Velocities", American Journal of Physics, volume 80, page 737, 2012. While the proof given there used Cartesian coordinate geometry, three alternative approaches are given in this article: a trigonometric one, one via Euclidean geometry, and one using projective geometry.

  12. Integration of geometric modeling and advanced finite element preprocessing

    Science.gov (United States)

    Shephard, Mark S.; Finnigan, Peter M.

    1987-01-01

    The structure to a geometry based finite element preprocessing system is presented. The key features of the system are the use of geometric operators to support all geometric calculations required for analysis model generation, and the use of a hierarchic boundary based data structure for the major data sets within the system. The approach presented can support the finite element modeling procedures used today as well as the fully automated procedures under development.

  13. Antenna with Dielectric Having Geometric Patterns

    Science.gov (United States)

    Dudley, Kenneth L. (Inventor); Elliott, Holly A. (Inventor); Cravey, Robin L. (Inventor); Connell, John W. (Inventor); Ghose, Sayata (Inventor); Watson, Kent A. (Inventor); Smith, Jr., Joseph G. (Inventor)

    2013-01-01

    An antenna includes a ground plane, a dielectric disposed on the ground plane, and an electrically-conductive radiator disposed on the dielectric. The dielectric includes at least one layer of a first dielectric material and a second dielectric material that collectively define a dielectric geometric pattern, which may comprise a fractal geometry. The radiator defines a radiator geometric pattern, and the dielectric geometric pattern is geometrically identical, or substantially geometrically identical, to the radiator geometric pattern.

  14. Morphometric assessment of uplifting coral reef sequences, Sumba Island, Indonesia

    Science.gov (United States)

    Nexer, Maëlle; Authemayou, Christine; Schildgen, Taylor; Hantoro, Wayhoe; Molliex, Stephane; Delcaillau, Bernard; Pedoja, Kevin; Husson, Laurent; Regard, Vincent

    2015-04-01

    Rates and patterns of vertical ground motions constitute a basic framework for understanding the kinematics of the deforming lithosphere. Calibrating morphometric indices with landscape maturity and tectonic deformation requires comparisons with regions of known uplift history. The ability to derive uplift histories from marine or reefal terrace analysis in coastal zones therefore makes such settings ideal for testing morpho-tectonic analysis techniques. To explore the relationships between uplift rates and landscape morphology, we studied a 300-km-long coastal stretch affected by slow to moderate uplift rates, varying laterally from ≈0.02 to ≈0.6 mm/yr. We exploited the systematic spatial variation in rock uplift rates recorded in well-dated sequences of coral reef terraces of Sumba Island to assess the manner and degree to which the eight morphometric indices selected for this study can be correlated with tectonic forcing. The uniform equatorial climate and lithology (most of the bedrock is composed of Quaternary reefal limestones) across the study area allow us to evaluate which morphometric indices best reflect the spatial variations in Pleistocene coastal uplift rates. Morphometric indices extracted from digital elevation models include residual relief, incision, stream length index, ksn, hypsometric integral, drainage area, mean relief, and shape factor. We calculated and extracted these indices at three scales: across the whole island, from grouped sequences of coral reef terraces undergoing comparable uplift rates and individual catchments draining mainly the coral reef zones located in the northern part of Sumba Island. We find that SL, hypsometric integral, mean relief and shape factor of catchments positively correlate with uplift rates, whereas incision, residual relief, and ksn do not. Interestingly enough, we find that only the areas that are uplifting at a rate faster than 0.3 mm/yr can yield the extreme values for these indices, implying in turn

  15. Quantitative diagnosis of bladder cancer by morphometric analysis of HE images

    Science.gov (United States)

    Wu, Binlin; Nebylitsa, Samantha V.; Mukherjee, Sushmita; Jain, Manu

    2015-02-01

    In clinical practice, histopathological analysis of biopsied tissue is the main method for bladder cancer diagnosis and prognosis. The diagnosis is performed by a pathologist based on the morphological features in the image of a hematoxylin and eosin (HE) stained tissue sample. This manuscript proposes algorithms to perform morphometric analysis on the HE images, quantify the features in the images, and discriminate bladder cancers with different grades, i.e. high grade and low grade. The nuclei are separated from the background and other types of cells such as red blood cells (RBCs) and immune cells using manual outlining, color deconvolution and image segmentation. A mask of nuclei is generated for each image for quantitative morphometric analysis. The features of the nuclei in the mask image including size, shape, orientation, and their spatial distributions are measured. To quantify local clustering and alignment of nuclei, we propose a 1-nearest-neighbor (1-NN) algorithm which measures nearest neighbor distance and nearest neighbor parallelism. The global distributions of the features are measured using statistics of the proposed parameters. A linear support vector machine (SVM) algorithm is used to classify the high grade and low grade bladder cancers. The results show using a particular group of nuclei such as large ones, and combining multiple parameters can achieve better discrimination. This study shows the proposed approach can potentially help expedite pathological diagnosis by triaging potentially suspicious biopsies.

  16. JMorph: Software for performing rapid morphometric measurements on digital images of fossil assemblages

    Science.gov (United States)

    Lelièvre, Peter G.; Grey, Melissa

    2017-08-01

    Quantitative morphometric analyses of form are widely used in palaeontology, especially for taxonomic and evolutionary research. These analyses can involve several measurements performed on hundreds or even thousands of samples. Performing measurements of size and shape on large assemblages of macro- or microfossil samples is generally infeasible or impossible with traditional instruments such as vernier calipers. Instead, digital image processing software is required to perform measurements via suitable digital images of samples. Many software packages exist for morphometric analyses but there is not much available for the integral stage of data collection, particularly for the measurement of the outlines of samples. Some software exists to automatically detect the outline of a fossil sample from a digital image. However, automatic outline detection methods may perform inadequately when samples have incomplete outlines or images contain poor contrast between the sample and staging background. Hence, a manual digitization approach may be the only option. We are not aware of any software packages that are designed specifically for efficient digital measurement of fossil assemblages with numerous samples, especially for the purposes of manual outline analysis. Throughout several previous studies, we have developed a new software tool, JMorph, that is custom-built for that task. JMorph provides the means to perform many different types of measurements, which we describe in this manuscript. We focus on JMorph's ability to rapidly and accurately digitize the outlines of fossils. JMorph is freely available from the authors.

  17. Quantifying traces of tool use: a novel morphometric analysis of damage patterns on percussive tools.

    Directory of Open Access Journals (Sweden)

    Matthew V Caruana

    Full Text Available Percussive technology continues to play an increasingly important role in understanding the evolution of tool use. Comparing the archaeological record with extractive foraging behaviors in nonhuman primates has focused on percussive implements as a key to investigating the origins of lithic technology. Despite this, archaeological approaches towards percussive tools have been obscured by a lack of standardized methodologies. Central to this issue have been the use of qualitative, non-diagnostic techniques to identify percussive tools from archaeological contexts. Here we describe a new morphometric method for distinguishing anthropogenically-generated damage patterns on percussive tools from naturally damaged river cobbles. We employ a geomatic approach through the use of three-dimensional scanning and geographical information systems software to statistically quantify the identification process in percussive technology research. This will strengthen current technological analyses of percussive tools in archaeological frameworks and open new avenues for translating behavioral inferences of early hominins from percussive damage patterns.

  18. Stabilization of LCD devices via geometric alteration.

    Science.gov (United States)

    Jeon, Il; Yoon, MinSung; Lee, Je-Hoon

    2013-02-20

    Glass bending in LCD displays is an inherent problem that has challenged many engineers. As a solution to this problem, we propose a methodology that can tackle the root of the phenomenon in terms of linear elastic beam theory. Using this hypothesis, we devised a background theory and a solution. In this paper, we present a glass panel to which geometrical changes, such as furrow, groove, and curb have been applied. These geometrical changes are applied to the nonactive area of the glass panel. To confirm the validity of our approach, we conducted simulation tests as well as hands-on experiments to observe the thermo-mechanical behavior of the device under various conditions. The simulation results using the Ansys simulator show that the proposed technique can reduce the deformation level of panel bending by 40%. In the experiment using a bare cell with polarizer films attached and with performing the high temperature reliability test, the deformation level of panel bending is reduced by half compared to the reference glass panel without any geometric alteration.

  19. Time as a geometric property of space

    Science.gov (United States)

    Chappell, James; Hartnett, John; Iannella, Nicolangelo; Iqbal, Azhar; Abbott, Derek

    2016-11-01

    The proper description of time remains a key unsolved problem in science. Newton conceived of time as absolute and universal which `flows equably without relation to anything external'. In the nineteenth century, the four-dimensional algebraic structure of the quaternions developed by Hamilton, inspired him to suggest that they could provide a unified representation of space and time. With the publishing of Einstein's theory of special relativity these ideas then lead to the generally accepted Minkowski spacetime formulation in 1908. Minkowski, though, rejected the formalism of quaternions suggested by Hamilton and adopted rather an approach using four-vectors. The Minkowski framework is indeed found to provide a versatile formalism for describing the relationship between space and time in accordance with Einstein's relativistic principles, but nevertheless fails to provide more fundamental insights into the nature of time itself. In order to answer this question we begin by exploring the geometric properties of three-dimensional space that we model using Clifford geometric algebra, which is found to contain sufficient complexity to provide a natural description of spacetime. This description using Clifford algebra is found to provide a natural alternative to the Minkowski formulation as well as providing new insights into the nature of time. Our main result is that time is the scalar component of a Clifford space and can be viewed as an intrinsic geometric property of three-dimensional space without the need for the specific addition of a fourth dimension.

  20. Time as a geometric property of space

    Directory of Open Access Journals (Sweden)

    James Michael Chappell

    2016-11-01

    Full Text Available The proper description of time remains a key unsolved problem in science. Newton conceived of time as absolute and universal which it `flows equably without relation to anything external'}. In the nineteenth century, the four-dimensional algebraic structure of the quaternions developed by Hamilton, inspired him to suggest that they could provide a unified representation of space and time. With the publishing of Einstein's theory of special relativity these ideas then lead to the generally accepted Minkowski spacetime formulation in 1908. Minkowski, though, rejected the formalism of quaternions suggested by Hamilton and adopted rather an approach using four-vectors. The Minkowski framework is indeed found to provide a versatile formalism for describing the relationship between space and time in accordance with Einstein's relativistic principles, but nevertheless fails to provide more fundamental insights into the nature of time itself. In order to answer this question we begin by exploring the geometric properties of three-dimensional space that we model using Clifford geometric algebra, which is found to contain sufficient complexity to provide a natural description of spacetime. This description using Clifford algebra is found to provide a natural alternative to the Minkowski formulation as well as providing new insights into the nature of time. Our main result is that time is the scalar component of a Clifford space and can be viewed as an intrinsic geometric property of three-dimensional space without the need for the specific addition of a fourth dimension.