نتایج جستجو برای: shape variation
تعداد نتایج: 477240 فیلتر نتایج به سال:
Characterization of morphological variation in the shells of extant Eastern Box Turtles, Terrapene carolina, provides a baseline for comparison to fossil populations. It also provides an example of the difficulties inherent to recognizing intraspecific diversity in the fossil record. The degree to which variation in fossils of T. carolina can be accommodated by extant variation in the species h...
The molecular chaperone protein Hsp90 has been widely discussed as a candidate gene for developmental buffering. We used the methods of geometric morphometrics to analyze its effects on the variation among individuals and fluctuating asymmetry of wing shape in Drosophila melanogaster. Three different experimental approaches were used to reduce Hsp90 activity. In the first experiment, developing...
Several studies investigating macroevolutionary skull shape variation in fossil reptiles were published recently, often using skull reconstructions taken from the scientific literature. However, this approach could be potentially problematic, because skull reconstructions might differ notably due to incompleteness and/or deformation of the material. Furthermore, the influence of intraspecific v...
The skull of leporids (rabbits and hares) is highly transformed, typified by pronounced arching of the dorsal skull and ventral flexion of the facial region (i.e., facial tilt). Previous studies show that locomotor behavior influences aspects of cranial shape in leporids, and here we use an extensive 3D geometric morphometrics dataset to further explore what influences leporid cranial diversity...
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 s...
surface topography and ultrastructure of dried cysts of artemia parthenogenetica (vedaranyam population) and bisexual artemia sp. (kelambakkam population) were studied electron microscopically in order to identify the bisexual strain, inhabiting covelong salterns, kelambakkam, south india. the scope of this study is to provide substantial information for further characterization of these artemi...
Introduction Template-based shape analysis has been widely used to assess structural shape abnormalities (volume loss and its location) in a variety of neurodegenerative and neuropsychiatric diseases. Thus far, most existing morphometric shape analysis has largely focused on a single structure, such as the hippocampus, or thalamus. Nevertheless, there is considerable morphological variation in ...
Anteroposterior (AP) pelvic radiographs only give a 2D projection of what is a 3D shape. Depending on the position of the patient while the radiograph is taken, the 2D projection of the shape may vary. This paper investigates the short-term variability of projected proximal femur shape using AP pelvic radiographs. We train a statistical shape model of the proximal femur based on a set of 87 rad...
Models of shape variations have become a central component for the automated analysis of images. An important class of shape models are point distribution models (PDMs). These models represent a class of shapes as a normal distribution of point variations, whose parameters are estimated from example shapes. Principal component analysis (PCA) is applied to obtain a low-dimensional representation...
following a magnetic survey in saghande yazd region, the existance of a relatively important dike shape anomaly was detected. in the present study, this anomaly has been interpreted by the werner deconvolution method and parker standard curves. the location and depth of the uper surface of magnetic dike has been calculated by the werner method using a series of profiles perpendicular to the str...
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