2,355 research outputs found

    Asymmetry of Caddo Ceramics from the Washington Square Mound Site: An Exploratory Analysis

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    While pursuing a study of 3D geometric morphometrics for ceramic burial vessels that often articulate with the Native American Graves Protection and Repatriation Act (NAGPRA) from the ancestral Caddo region, there have been no shortage of potentially meaningful observations, one of which--rotational asymmetry in coil-built vessels--is discussed here. Using Geomagic Design X (reverse-engineering software) and Geomagic Control X (inspection software), metrics associated with rotational asymmetry were generated then analyzed. Results indicate variable asymmetry among the different vessel shapes (i.e., bottles, jars, etc.), which may augment and strengthen studies and discussion of vessel form. Future directions include the incorporation of directional and--possibly--fluctuating asymmetry measures for the widest vessel profiles. Preliminary results point toward substantive analytical gains that can be used to augment more traditional ceramic analyses as well as geometric morphometric studies of ceramic vessel shape

    A novel method for pair-matching using three-dimensional digital models of bone:mesh-to-mesh value comparison

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    The commingling of human remains often hinders forensic/physical anthropologists during the identification process, as there are limited methods to accurately sort these remains. This study investigates a new method for pair-matching, a common individualization technique, which uses digital three-dimensional models of bone: mesh-to-mesh value comparison (MVC). The MVC method digitally compares the entire three-dimensional geometry of two bones at once to produce a single value to indicate their similarity. Two different versions of this method, one manual and the other automated, were created and then tested for how well they accurately pair-matched humeri. Each version was assessed using sensitivity and specificity. The manual mesh-to-mesh value comparison method was 100 % sensitive and 100 % specific. The automated mesh-to-mesh value comparison method was 95 % sensitive and 60 % specific. Our results indicate that the mesh-to-mesh value comparison method overall is a powerful new tool for accurately pair-matching commingled skeletal elements, although the automated version still needs improvement. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00414-016-1334-3) contains supplementary material, which is available to authorized users

    Wings of Coenagrion puella vary in shape at the northern range margin (Odonata: Coenagrionidae)

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    A previous study has shown that wing size in Coenagrion puella varied considerably along a latitudinal gradient in the UK. Using landmark data from wing images, patterns of shape variation were also determined along the same transect by geometric morphometric analysis of wing shape. Wing shape was uniform at all sites other than those closest to the range margin, which differed significantly. The potential mechanisms that might have generated such between-population variation are discussed

    Three Dimensional Nonlinear Statistical Modeling Framework for Morphological Analysis

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    This dissertation describes a novel three-dimensional (3D) morphometric analysis framework for building statistical shape models and identifying shape differences between populations. This research generalizes the use of anatomical atlases on more complex anatomy as in case of irregular, flat bones, and bones with deformity and irregular bone growth. The foundations for this framework are: 1) Anatomical atlases which allow the creation of homologues anatomical models across populations; 2) Statistical representation for output models in a compact form to capture both local and global shape variation across populations; 3) Shape Analysis using automated 3D landmarking and surface matching. The proposed framework has various applications in clinical, forensic and physical anthropology fields. Extensive research has been published in peer-reviewed image processing, forensic anthropology, physical anthropology, biomedical engineering, and clinical orthopedics conferences and journals. The forthcoming discussion of existing methods for morphometric analysis, including manual and semi-automatic methods, addresses the need for automation of morphometric analysis and statistical atlases. Explanations of these existing methods for the construction of statistical shape models, including benefits and limitations of each method, provide evidence of the necessity for such a novel algorithm. A novel approach was taken to achieve accurate point correspondence in case of irregular and deformed anatomy. This was achieved using a scale space approach to detect prominent scale invariant features. These features were then matched and registered using a novel multi-scale method, utilizing both coordinate data as well as shape descriptors, followed by an overall surface deformation using a new constrained free-form deformation. Applications of output statistical atlases are discussed, including forensic applications for the skull sexing, as well as physical anthropology applications, such as asymmetry in clavicles. Clinical applications in pelvis reconstruction and studying of lumbar kinematics and studying thickness of bone and soft tissue are also discussed

    Evaluating the Effectiveness of Cranial Molding for Treatment of Positional Plagiocephaly Using Finite Element Analysis

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    Since the advent of recommendations for placing infants in the supine position during sleep to reduce the incidence of sudden infant death syndrome, clinicians have noted an increase in the frequency of cranial asymmetry due to deformation of suture sections of the infants’ skulls as a result of constant concentrated stress in one area at the back of their head. This specific form of cranial deformation is known as positional plagiocephaly and its rate of occurrence has increased from 0.3% in 8.2% within the past 30 years. Current treatments and methodologies for preventing and correcting positional plagiocephaly such as stretching exercises, bedding pillows, and cranial molding are not optimized for effectiveness and comfort. Literature surrounding the implementation of these methodologies or devices often assesses the relative effectiveness of each treatment through statistical means, or studies complications associated with their use. There is a lack of quantified mechanical analysis for determining the effectiveness of each treatment or engineered solutions. In this study, a finite element model was created and validated to study the effect of wearing a cranial helmet, as the most effective non-surgical device for treatment of positional plagiocephaly, on reducing concentrated stress from the back of the baby’s head during sleep. The results from this model were then compared to two other finite element models with a healthy baby sleeping in supine position on a pillow, and a patient diagnosed with a severe case of positional plagiocephaly sleeping on the flat side of his head in supine position. The geometries representing the head of the babies in these models are the refined 3D laser-scanned file of a patient’s head contour at Hanger Clinic as well as the cavity inside the cranial helmet that was used for treatment of the baby. After successfully assigning section and contact properties to different regions of the models, applying proper loading and boundary conditions, and performing mesh convergence studies for each of the three models, the average Von Mises stress values of each of the 13 different suture segments of each model were summarized in tables and evaluated using mathematical and qualitative methods. The stress value data obtained from different suture regions of the model with the cranial helmet resulted in the smallest standard deviation among all three populations which supports that wearing the cranial helmet helps to reduce stress concentrations. Use of the cranial helmet during sleep also showed a significant decrease of the average Von Mises stress within the posterior fontanelle by 90% compared to the healthy baby sleeping in supine position and 73.4% compared to the deformed head sleeping on the flat surface of the head. The major limitations of this study are correlated with the simplifying assumptions and geometries in generating and validating the models. Future studies need to focus on overcoming these limitations and generating more complex models using a similar approach. The methods used in this study and the results obtained from the models can serve as a basis for future development of engineered solutions that are more effective than the existing solutions in the market and reduce the side-effects and complications associated with their use

    Advances in Geometric Morphometrics

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    First Record of Reversed Symmetry in Etropus cyclosquamus and Second Record in Citharichthys spilopterus (Bothidae, Pisces) in the Gulf of Mexico, with a Plausible Genetic Explanation for Reversal

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    The discovery of the first instance of reversed eye symmetry in the shelf flounder, Etropus cyclosquamus, and the second instance in the bay whiff, Citharichthys spilopterus, are reported. Two reversed bay whiffs and three reversed shelf flounders were collected in the Gulf of Mexico. Four of these specimens were taken from the vicinity of Fort Walton Beach, Okaloosa County, in northern Florida, and one was taken from Higgs Beach in Key West, Monroe County, Fl. The collection of these fish is reported because of the infrequent occurrence of reversed eye symmetry in flatfishes in the Gulf of Mexico. The fish serve as the first record of eye symmetry reversal in E. cyclosquamus and the second record for C. spilopterus in the Gulf of Mexico. This is the second record of reversal for the genus Etropus and the third record for Citharichthys in the western Atlantic Ocean. The putative causes of symmetry reversal in pleuronectiform fish are briefly examined. A plausible genetic explanation for reversal is proposed. The explanation attempts to reconcile the environmental causality of eye symmetry with the accepted genetic model of Brown and Wolpert

    Modeling meander morphodynamics over self-formed heterogeneous floodplains

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    This work addresses the signatures embedded in the planform geometry of meandering rivers consequent to the formation of floodplain heterogeneities as the river bends migrate. Two geomorphic features are specifically considered: scroll bars produced by lateral accretion of point bars at convex banks and oxbow lake fills consequent to neck cutoffs. The sedimentary architecture of these geomorphic units depends on the type and amount of sediment, and controls bank erodibility as the river impinges on them, favoring or contrasting the river migration. The geometry of numerically generated planforms obtained for different scenarios of floodplain heterogeneity is compared to that of natural meandering paths. Half meander metrics and spatial distribution of channel curvatures are used to disclose the complexity embedded in meandering geometry. Fourier Analysis, Principal Component Analysis, Singular Spectrum Analysis and Multivariate Singular Spectrum Analysis are used to emphasize the subtle but crucial differences which may emerge between apparently similar configurations. A closer similarity between observed and simulated planforms is attained when fully coupling flow and sediment dynamics (fully-coupled models) and when considering self-formed heterogeneities that are less erodible than the surrounding floodplain

    The Application of NextEngine Scanning Technology to Commingled Skeletal Analysis at the Milwaukee County Poor Farm Cemetery: A Replicable Method for Restoring Individuality

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    The analysis and subsequent disentanglement of human skeletal elements from commingled or mixed burial contexts is an essential step in creating individual identifications of those individuals represented in these burials. This work is integral to the overall goal of using methodologically robust techniques to contextualize and represent individuals recovered in archaeological or forensic settings. A suite of commingled burial analysis methods are currently used to achieve this goal. These methods are essential to the field, but can still introduce error. To provide additional lines of evidence to support these analyses, this study investigates the efficacy of a three-dimensional pair-matching technique, using a NextEngineâ„¢ scanner and both open source and proprietary software to test two methods of mesh-to-mesh value comparison for reliability and replicability
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