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Dive into the research topics where Luci Ann P. Kohn is active.

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Featured researches published by Luci Ann P. Kohn.


Evolution | 1988

How similar are genetic correlation structures? Data from mice and rats

Luci Ann P. Kohn; William R. Atchley

An integral assumption of many models of morphometric evolution is the equality of the genetic variance‐covariance structure across evolutionary time. To examine this assumption, the quantitative‐genetic aspects of morphometric form are examined for eight pelvic traits in laboratory rats (Rattus norvegicus) and random‐bred ICR mice (Mus musculus). In both species, all traits are significantly heritable, and there are significant phenotypic and genetic correlations among traits, although environmental correlations among the eight traits are low. The size relations among the pelvic variables are isometric. Three matrix‐permutation tests are used to examine similarity of phenotypic, genetic, and environmental covariance and correlation matrices within and between species. Independent patterns of morphometric covariation and correlation arise from genetic and environmental effects within each species and from environmental effects between species. The patterns of phenotypic and genetic covariation and correlation are similar within each species, and the phenotypic and genetic correlations are also similar between these species. However, genetic covariance matrices show no significant statistical association between species. It is suggested that the assumption of equality of genetic variance‐covariance structures across divergent taxa should be approached with caution.


Journal of Neuroscience Methods | 1991

Human cortical asymmetries determined with 3D MR technology

Dean Falk; Charles F. Hildebolt; James M. Cheverud; Luci Ann P. Kohn; Gary S. Figiel; Michael W. Vannier

A method is described for obtaining clear 3D magnetic resonance (MR) images of the cortical surface of the brain in living human subjects. By combining volume composite and depth encoded images, we have obtained surface coordinate data that resulted in highly repeatable measurements of sulcal lengths and cortical surface areas in eight normal adult volunteers. Sulcal lengths were determined for specific parts of the Sylvian fissure, central sulcus and frontal operculum. Additionally, angles were computed between the anterior and posterior limbs of the pars triangularis and the ascending and horizontal limbs of the posterior Sylvian fissure. The cortical surface areas enclosed by these limbs were also computed. Finally, thirteen non-metric cortical features (e.g., petalias) were scored from the 3D MR images. All measurements were compared in right and left hemispheres. In addition to corroborating cortical asymmetries reported in the literature, we observed previously unrecognized directional asymmetries in the length of the anterior limb of the pars triangularis, length of the ascending limb of the posterior Sylvian fissure, and position of the lateral end of the central sulcus. We attribute the finding of three new directional asymmetries for the human cortex, as well as the high repeatability of our measurements, to the sensitivity and accuracy of the 3D MR imaging technology that has recently become available.


Annals of Plastic Surgery | 1995

Anthropometric optical surface imaging system repeatability, precision, and validation

Luci Ann P. Kohn; James M. Cheverud; Gulab H. Bhatia; Paul K. Commean; Kirk E. Smith; Michael W. Vannier

Disciplines using human body surface dimensions require accurate, repeatable measurements. This study presents a design for the analysis of repeatability, precision, and validation of a new anthropometric device. This model enables estimation of the proportion of the total variation attributable to each level of data collection. This model is applied to an analysis of repeatability, precision, and validation of the Cencit Imaging System, a new optical surface scanner. Twenty-seven facial landmarks were marked on 10 men and 10 women at two measurement sessions. Two images were scanned during each session, and each image was digitized twice. The Cencit Imaging System results were compared with a previously validated digitizer. The Cencit Imaging System was found to produce accurate, highly repeatable images. Much of the error in this study is attributable to human error in marking landmarks on the subjects. The new imaging system will prove useful in a variety of anthropometric applications.


American Journal of Primatology | 1997

Age of Epiphyseal Closure in Tamarins and Marmosets

Luci Ann P. Kohn; Paul Olson; James M. Cheverud

Estimates of the chronological age for animals of unknown age provide useful information for medical, demographic, and evolutionary studies. Skeletal development, as indicated by epiphyseal closure, can be used to estimate an animals chronological age or specify its stage of development. Many studies of Primate skeletal development have used animals of unknown age, with the order of epiphyseal closure providing a relative age for each animal. This study examines the age of epiphyseal closure at 22 epiphyseal sites using animals of known age at death in three calitrichid species (Saguinus fuscicollis, Saguinus oedipus, and Callithrix jacchus). The observed average age of epiphyseal closure is similar in these tamarins and marmosets. There is a significant difference in rate of development between the species. Regression equations can predict the age of unknown animals to within 4.8 months for S. fuscicollis, 8.6 months for S. oedipus, and 7.6 months for C. jacchus (twice the standard error of the estimate). These age estimates allow us to determine if an animal is relatively mature or immature, but are largely unacceptable for studies in which precise age estimates are necessary. The order of epiphyseal closure is similar across 11 monkey species (using additional data from published literature) and supports the suggestion of a general pattern in Primate skeletal development. Am. J. Primatol. 41:129–139, 1997.


The Cleft Palate-Craniofacial Journal | 1994

Effect of premature sagittal suture closure on craniofacial morphology in a prehistoric male hopi

Luci Ann P. Kohn; Michael W. Vannier; Jeffrey L. Marsh; James M. Cheverud

Scaphocephaly is caused by premature sagittal suture closure. It restricts medial-lateral growth of the cranial vault which appears longer and narrower than normal. We examined how this natural malformation affected morphology of the cranial base and face. A prehistoric adult male Hopi with scaphocephaly was compared to 19 normal male Hopi (Old Walpi Series, Field Museum of Natural History, Chicago, IL). Three-dimensional coordinates of 53 landmarks were recorded on the cranial vault, cranial base, and face. Finite element scaling analysis was used to test for significant differences between the scaphocephalic and normal individuals in craniofacial morphology. Finite element scaling results indicated that scaphocephaly has a profound effect on cranial vault morphology. However, morphology of the cranial base and face were only slightly affected and, typically, are within the normal range of variation for the sample. An abnormality in the cranial base is not associated with scaphocephaly in this individual.


Journal of Mammalogy | 2010

Morphometric evaluation of the two mink subspecies in Illinois

James E. Peters; Ralph W. Axtell; Luci Ann P. Kohn

Abstract The 2 subspecies of mink (Neovison vison letifera and N. v. mink) in Illinois were characterized early in the 20th century; however, quantifiable morphological distinctions between the 2 subspecies remain unclear. Illinois biogeography, and the influence of glaciations on animal populations, might explain the distinctions between the 2 mink subspecies. We evaluated sexual dimorphism within each subspecies and morphologic variation between subspecific populations. Oral, facial, and braincase regions were defined by 22 dimensions. Sexual dimorphism was present in both subspecies of mink. Data were adjusted for sex differences and tested for differences between subspecies using analysis of variance and multivariate analysis of variance. Cranial dimensions differed significantly between N. v. letifera and N. v. mink. Cranial dimensions distinguish individuals of the 2 geographically distinct subspecies; however, an intergradation zone might be present. The results are consistent with population response to glaciations and subsequent expansion, however, further genetic testing is necessary to test this historical biogeography of N. vison.


Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology | 2018

Postcranial skeletal differences in free-range and captive-born primates: Free-range and captive-born postcranial form

Luci Ann P. Kohn; Gabriele R. Lubach

Skeletal morphology is important in evolutionary, genetic, developmental, physiological, and functional studies. Although samples from free‐ranging individuals may be preferable, constraints of sample size, demography, or conservation status may necessitate the inclusion of captive‐born individuals. Captivity may be associated with physical, physiological, or behavioral differences that may affect skeletal form. This study assesses differences in postcranial skeletal form between free‐range and captive‐born Macaca mulatta and Saguinus oedipus. Samples included free‐range M. mulatta from Cayo Santiago (Caribbean Primate Research Center) and captive‐born macaques from the Wisconsin National Primate Research Center. S. oedipus samples included free‐range born and captive‐born individuals from the Oak Ridge Associated Universities Marmoset Research Center. Twenty‐four dimensions of various bones, including the scapula, upper limb, innominate and lower limb, were recorded for adults. Age of epiphyseal closure was recorded for immature captive‐born M. mulatta. Analysis of variance and principal component analyses tested significant differences between free‐range born and captive‐born individuals in each species. Significant differences were present in size and shape of postcrania between free‐range and captive‐born within taxa. Free‐range macaques were larger than captive‐born macaques, but this pattern did not consistently carry over to the Saguinus samples. Shape differences, while present throughout the skeleton, were especially prominent in the scapula. Differences in developmental timing, nutrition, and physical activity can be expected to contribute to the observed differences in postcranial skeletal form. These differences should be considered when captive‐born primates are included in morphological or evolutionary studies. Anat Rec, 2018.


American Journal of Physical Anthropology | 1992

Effects of fronto-occipital artificial cranial vault modification on the cranial base and face

James M. Cheverud; Luci Ann P. Kohn; Lyle W. Konigsberg; Steven R. Leigh


American Journal of Physical Anthropology | 1993

Cranial deformation and nonmetric trait variation

Lyle W. Konigsberg; Luci Ann P. Kohn; James M. Cheverud


American Journal of Physical Anthropology | 1993

Effects of Annular Cranial Vault Modification on the Cranial Base and Face

Luci Ann P. Kohn; Steven R. Leigh; Susan C. Jacobs; James M. Cheverud

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Steven R. Leigh

University of Colorado Boulder

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A. Alison Plummer

University of Wisconsin-Madison

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Bruce Riska

University of Wisconsin-Madison

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Charles F. Hildebolt

Washington University in St. Louis

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Dean Falk

Florida State University

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Gabriele R. Lubach

University of Wisconsin-Madison

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Gary S. Figiel

Washington University in St. Louis

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Gulab H. Bhatia

Washington University in St. Louis

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