1,721,017 research outputs found
Analyzing the Impact of Population Level Differences and Socioeconomic Status on Subadult Age Estimation
Full text linkThe University of Nevada, Reno Libraries will promptly respond to removal requests related to content that violates intellectual property laws, data protections, or has been uploaded without creator consent. Takedown notices should be directed to our ScholarWolf team ([email protected]) with information about the object, including its full URL and the nature of your complaint.Age estimation is usually the sole contribution to the biological profile of a skeletally immature individual. Forensic anthropologists use dental and skeletal development to estimate age. It is regularly stated that there needs to be population-specific methods of age estimation that encompass population level and socioeconomic status differences (Esan, Yengopal, & Schepartz, 2017). While both population differences and SES is recognized as influencing growth, it is not known at what age the population differences or SES differences become apparent or influential to age estimations. The purpose of this study is to compare the skeletal and dental formations of South African and United States individuals aged 0-6 as a means to determine if differences in diaphyseal length and molar formation exist between the populations and if so, to quantify the magnitude. Furthermore, the study will create population specific and global models and test the accuracy and precision of MARS model
Asymmetry and discordance in Carabelli’s trait and the hypocone: do MZ and DZ twins point to common underlying epigenetic factors?
No full textFamily and twin studies show there is a strong genetic component underlying the development of nonmetric tooth crown traits. If nonmetric dental traits are controlled by genes alone, then it is expected that (1) left and right antimeres should exhibit identical trait expressions, and (2) MZ twins, with identical genotypes, should display identical phenotypes. However, antimeres exhibit some asymmetry in trait expression and MZ twins likewise exhibit some level of discordant trait expression. Antimere asymmetry and MZ twin discordance suggest there are factors at work beyond genes that moderate crown trait expression, suggesting the possible action of common, underlying epigenetic mechanisms.This study looks beyond the classic “genetically controlled” paradigm of nonmetric crown tooth traits by examining the level of asymmetry and discordance in Carabelli’s cusp and the hypocone of 288 Australian monozygotic (MZ) and dizygotic (DZ) twin pairs. The level of asymmetry between antimeres is almost identical for MZ and DZ twins. Scores for discordance were similar for MZ twins but were consistently lower for all DZ twins. This study shows that measures of asymmetry in both twin types and discordance in MZ twins are almost identical, suggesting both are likely caused by epigenetic factors operating at the same magnitude. However, these factors may work independently on asymmetry and discordance as they do not covary in twins. As an ancillary test, birth weight data were compared to asymmetry and discordance scores in MZ and DZ twins. Neither absolute birth weights nor birth weight differences between twins were associated with levels of asymmetry or discordance. Birth weight, as a reflection of developmental perturbations and prenatal stress during pregnancy, was not reflected in the development of asymmetry or MZ twin discordance in Carabelli’s trait and the hypocone. Furthermore, sex of the twin pair had no correlation with the development of asymmetry of discordance
Desert Conservation Priorities Mapping Tool
No full textDevelopment of public land use within the Desert Renewable Energy Conservation Plan (DRECP) boundary is taking place through collaboration of the California Energy Commission (CEC), the U.S. Fish and Wildlife Service (USFWS), the California Department of Fish and Wildlife (CDFW) and the U.S. Bureau of Land Management (USBLM) in order to 1) identify areas of land with high-quality renewable energy potential and 2) provide for the long-term conservation and management of endangered and threatened species as well as areas of biological, physical, cultural and social importance. The DRECP covers 22,585,000 acres of southern California, encompassing the Mojave and Colorado Deserts. Home to threatened, endangered and protected (TEP) species, endemic lineages and evolutionary hotspots, the desert biota face widespread threats (e.g. human development, subsidized predation, linear corridors, off-highway vehicles, military training, invasive plants, climate change, and renewable energy). Privately owned land existing within the DRECP provides potential opportunities for private environmental organizations to expand on federal and state landscape-scale conservation efforts. I will be showcasing a spatially explicit decision support system (DSS) that was built to help a private environmental organization identify parcels to target for land acquisition, conservation, and restoration. Differing from others in its versatility and its weighting scheme, this DSS works under differing conservation scenarios (e.g. conservation vs restoration) and includes nonlinear weighting of criterion (attribute) values, providing more flexibility to the decision maker when assigning weights to evaluation criteria
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
An osteometric evaluation of age and sex differences in the long bones of South African children from the Western Cape
Full text linkThesis (PhD)--University of Pretoria, 2013.The main goal of a forensic anthropological analysis of unidentified human remains is to
establish an accurate biological profile. The largest obstacle in the creation or validation of
techniques specific for subadults is the lack of large, modern samples. Techniques created for
subadults were mainly derived from antiquated North American or European samples and thus
inapplicable to a modern South African population as the techniques lack diversity and ignore
the secular trends in modern children. This research provides accurate and reliable methods to
estimate age and sex of South African subadults aged birth to 12 years from long bone lengths
and breadths, as no appropriate techniques exist.
Standard postcraniometric variables (n = 18) were collected from six long bones on 1380
(males = 804, females = 506) Lodox Statscan-generated radiographic images housed at the
Forensic Pathology Service, Salt River and the Red Cross War Memorial Children’s Hospital in
Cape Town, South Africa. Measurement definitions were derived from and/or follow studies in
fetal and subadult osteology and longitudinal growth studies. Radiographic images were
generated between 2007 and 2012, thus the majority of children (70%) were born after 2000 and
thus reflect the modern population.
Because basis splines and multivariate adaptive regression splines (MARS) are
nonparametric the 95% prediction intervals associated with each age at death model were
calculated with cross-validation. Numerous classification methods were employed namely linear,
quadratic, and flexible discriminant analysis, logistic regression, naïve Bayes, and random
forests to identify the method that consistently yielded the lowest error rates. Because some of
the multivariate subsets demonstrated small sample sizes, the classification accuracies were
bootstrapped to validate results. Both univariate and multivariate models were employed in the
age and sex estimation analyses.
Standard errors for the age estimation models were smaller in most of the multivariate
models with the exception of the univariate humerus, femur, and tibia diaphyseal lengths.
Univariate models provide narrower age estimates at the younger ages but the multivariate
models provide narrower age estimates at the older ages. Diaphyseal lengths did not demonstrate
any significant sex differences at any age, but diaphyseal breadths demonstrated significant sex
differences throughout the majority of the ages. Classification methods utilizing multivariate
subsets achieved the highest accuracies, which offer practical applicability in forensic
anthropology (81% to 90%). Whereas logistic regression yielded the highest classification
accuracies for univariate models, FDA yielded the highest classification accuracies for
multivariate models. This study is the first to successfully estimate subadult age and sex using an
extensive number of measurements, univariate and multivariate models, and robust statistical
analyses. The success of the current study is directly related to the large, modern sample size,
which ultimately captured a wider range of human variation than previously collected for
subadult diaphyseal dimensions.gm2014Anatomyunrestricte
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Postcraniometric analysis of ancestry among modern South Africans
Full text linkDissertation (MSc (Anatomy))--University of Pretoria, 2014.The primary role of a physical anthropologist is to provide sufficient information to assist in
the individualisation of unknown skeletal remains. This is often achieved in establishing a
biological profile of the deceased, of which ancestry is an essential aspect. Several successful
osteometric and morphological approaches have been developed to facilitate the estimation of
ancestry from the cranium. However, the cranium is not always available for analysis,
emphasising a need for postcranial alternatives. The postcranial skeleton is frequently
labelled as too variable and unreliable to provide an accurate assessment of ancestry. Yet,
numerous studies utilise the postcrania for sex and stature estimation, where the a priori
knowledge of ancestry results in higher accuracy. Thus, the presence of postcranial
differences among populations when investigating other biological parameters inherently
demonstrates the potential for the estimation of ancestry. The purpose of this study was to
quantify postcranial variation among modern, peer-reported black, white and coloured South
Africans. A series of 39 standard measurements were taken from 11 postcranial bones,
namely the clavicle, scapula, humerus, radius, ulna, sacrum, pelvis, femur, tibia, fibula and
calcaneus. The sample consisted of 360 modern South African individuals (120 black, 120
white, 120 coloured) from the Pretoria Bone and Kirsten Collections housed at the University
of Pretoria and the University of Stellenbosch, respectively. Group differences were explored
with ANOVA and Tukey’s honestly significant difference test (HSD). Group means were
used to create univariate sectioning points for each variable indicated as significant with
ANOVA. Where two of the three groups had similar mean values, the groups were pooled for
the creation of the sectioning points. Multivariate classification models were employed using
linear and flexible discriminant analysis (LDA and FDA, respectively). Classification
accuracies were compared to evaluate which model yielded the best results.
The results demonstrated variable patterns of group overlap. Black and coloured South
Africans displayed similar means for breadth measurements, and black and white South
Africans showed similar means for the maximum length of distal limb elements. The majority
of group variation is attributed to differences in size and robusticity, where white South
Africans are overall larger and more robust than black and coloured South Africans.
Accuracies for the univariate sectioning points ranged from 43% to 87%, with iliac breadth
performing the best. However, the majority of the univariate sectioning points can only
classify individuals into two groups rather than three because of similar group means.
Multivariate bone models created using all measurements per bone resulted in accuracies ranging from 46% to 62% (LDA) and 41% to 66% (FDA). Multivariate subsets consisting of
numerous different measurement combinations from several skeletal elements achieved
accuracies as high as 85% (LDA) and 87% (FDA).
Ultimately the best results were achieved using combinations of different variables
from several skeletal elements. Overall, the multivariate models yielded better results than the
univariate approach, as the inclusion of more variables is generally better for maximising
group differences. Furthermore, FDA achieved higher accuracies than the more traditional
approach of LDA. Despite the significant overlap among the groups, the postcranial skeleton
has proven to be proficient in distinguishing the three groups. Thus, even in a heterogeneous
population, a multivariate postcraniometric approach can be used to estimate ancestry with
high accuracy.AnatomyUnrestricte
Evaluation of Bone’s Response to Force: Fracture Type, Fracture Location, and Fracture Severity Across the Female Lifespan
Full text linkTrauma analysis and interpretation is a key component for forensic anthropologists and pathologists during any analysis of remains. Though studies have identified a positive relationship between increased age and higher risk of fracture, the field of anthropology is lacking a deeper understanding of how bone responds to force based on application of intrinsic and extrinsic factors. The current study evaluated the change in fracture type, location, and severity in women, exploring how endogenous hormones may impact bone’s response to force. Data were collected from the Washoe County Regional Medical Examiner’s Office and the Reno Orthopedic Clinic and included a sample of 263 women between the ages of 20 and 80 years. The analyses were separated by menopausal state (assumed by chronological age), by age decades, and by institution. The relationship between increased age and fracture location on bone was found to be statistically significant, indicating fracture location shifts with age. Additionally, fracture completeness is positively related to an increase in age. This research can be used to aid anthropologists in the future to facilitate a deeper understanding of trauma and how variation in intrinsic factors impact how bone responds to force
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