Papers by Dawnie Steadman
This chapter explores the evolving role of forensic genetics in human rights investigations and a... more This chapter explores the evolving role of forensic genetics in human rights investigations and as a technology of postmortem identification for missing persons in ongoing conflict and post-conflict societies. How has DNA’s increasingly privileged place as a line of evidence impacted the field in terms of both medico-legal standards and heightened expectations among surviving kin and their communities? Drawing on interviews with leading figures in the field of forensic science and human rights/transitional justice (e.g., the International Commission on Missing Persons, the International Committee of the Red Cross, the Equipo Argentino de Antropología Forense, and the Colibrí Center for Human Rights), buttressed by ethnographic analysis of exhumation and identification efforts in Bosnia and Herzegovina and Uganda, the chapter provides an overview and commentary about the technology’s complicated place in unearthing truths and effecting repair.
ArXiv, 2020
Large collections of images, if curated, drastically contribute to the quality of research in man... more Large collections of images, if curated, drastically contribute to the quality of research in many domains. Unsupervised clustering is an intuitive, yet effective step towards curating such datasets. In this work, we present a workflow for unsupervisedly clustering a large collection of forensic images. The workflow utilizes classic clustering on deep feature representation of the images in addition to domain-related data to group them together. Our manual evaluation shows a purity of 89\% for the resulted clusters.
ArXiv, 2021
Annotating images for semantic segmentation requires intense manual labor and is a time-consuming... more Annotating images for semantic segmentation requires intense manual labor and is a time-consuming and expensive task especially for domains with a scarcity of experts, such as Forensic Anthropology. We leverage the evolving nature of images depicting the decay process in human decomposition data to design a simple yet effective pseudo-pixel-level label generation technique to reduce the amount of effort for manual annotation of such images. We first identify sequences of images with a minimum variation that are most suitable to share the same or similar annotation using an unsupervised approach. Given one user-annotated image in each sequence, we propagate the annotation to the remaining images in the sequence by merging it with annotations produced by a state-of-the-art CAM-based pseudo label generation technique. To evaluate the quality of our pseudo-pixel-level labels, we train two semantic segmentation models with VGG and ResNet backbones on images labeled using our pseudo label...
2020 IEEE International Conference on Image Processing (ICIP), 2020
Domain-specific image collections present potential value in various areas of science and busines... more Domain-specific image collections present potential value in various areas of science and business but are often not curated nor have any way to readily extract relevant content. To employ contemporary supervised image analysis methods on such image data, they must first be cleaned and organized, and then manually labeled for the nomenclature employed in the specific domain, which is a time consuming and expensive endeavor. To address this issue, we designed and implemented the Plud system. Plud provides an iterative semi-supervised workflow to minimize the effort spent by an expert and, due to the fact that it does not make any assumption about its input, can handle realistic large collections of images regardless of their size and type. Plud is an iterative sequence of unsupervised clustering, human assistance, and supervised classification. With each iteration 1) the labeled dataset grows, 2) the generality of the classification method and its accuracy increases, and 3) manual ef...
Lipidomic analyses of human skeletal muscle tissue were conducted to detect biomarkers of time-de... more Lipidomic analyses of human skeletal muscle tissue were conducted to detect biomarkers of time-dependent postmortem degradation and to test the predictive capacity of lipids in human skeletal muscle cell membranes. High-resolution mass spectrometry analytical platforms were used to isolate phospholipids in muscle cell membranes that are specific to the corpse tissues and not invading microbes, thus eliminating potential noise from the surrounding microenvironment. The most consistently extracted cell membrane phospholipids were phosphatidylglycerol (PG) 34:0 and phosphatidylethanolamine (PtdE) 36:4. The actual accumulated degree days of all validation samples fell within the 95% prediction interval limits for the simple linear regression models with PtdE 36:4 and PG 34:0, though the prediction intervals for the latter were wider. The analysis requires only a small amount of tissue, is less subjective than visual methods for estimating postmortem interval, and is robust to drastic fl...
In many domains, large image collections are key ways in which information about relevant phenome... more In many domains, large image collections are key ways in which information about relevant phenomena is retained and analyzed, yet it remains challenging to use such data in research and practice. Our aim is to investigate this problem in the context of a forensic unlabeled dataset of over 1M human decomposition photos. To make this collection usable by experts, various body parts first need to be identified and traced through their evolution despite their distinct appearances at different stages of decay from "fresh" to "skeletonized". We developed an unsupervised technique for clustering images that builds sequences of similar images representing the evolution of each body part through stages of decomposition. Evaluation of our method on 34,476 human decomposition images shows that our method significantly outperforms the state of the art clustering method in this application.
2019 IEEE International Conference on Image Processing (ICIP)
Forensic Anthropology
Stable isotope analysis of postmortem hair is performed in order to make inferences about an indi... more Stable isotope analysis of postmortem hair is performed in order to make inferences about an individual’s diet and geographic travel history prior to death. During analysis and interpretation, investigators assume that the hair collected from a postmortem environment has not been altered by exposure conditions and that the isotopic “signatures” of hair prior to exposure are preserved in postmortem samples. In order to confidently make inferences from postmortem hair samples, it is necessary to know whether their isotope ratios undergo postmortem changes. To address this question, post-exposure hair samples (n = 44) were collected from known body donors at the Anthropology Research Facility in Knoxville, Tennessee, USA, at various time points ranging from 22 to 1,140 days of exposure. These samples were analyzed for carbon (δ13C), nitrogen (δ15N), hydrogen (δ2H), and oxygen (δ18O) isotope ratios, and the results were compared with pre-exposure hair samples collected from the same don...
American Journal of Physical Anthropology
OBJECTIVES The Falys-Prangle-method assesses age-related morphological changes to the sternal cla... more OBJECTIVES The Falys-Prangle-method assesses age-related morphological changes to the sternal clavicle end (SCE), enabling the observation of mature adults from the 5th decade onwards in unburnt human skeletal remains. The aim of this study is to investigate the applicability of the Falys-Prangle-method on burnt human remains. MATERIALS AND METHODS Fifty-two SCE of 40 cremated individuals (out of 86) from the William M. Bass collection of the Forensic Anthropology Center (Knoxville, Tennessee) of known age-at-death and sex are available for assessment. Surface topography, porosity, and osteophyte formation are evaluated, after which the calculated composite score is associated with the corresponding age range as described by Falys and Prangle. The method is also applied on an archaeological case study from Oudenburg, Belgium, dating to the Roman period. RESULTS The assessed age ranges strongly agree with the true age ranges (α = 0.828), suggesting the Falys-Prangle-method to be applicable on burnt human remains. The case study from Oudenburg yields markedly improved age-at-death estimates, significantly enhancing our understanding of the age distribution within this community. DISCUSSION Information on age-at-death is key in the construction of biological profiles of past individuals. The mature adult is often invisible in the archaeological record since most macroscopic age estimation methods do not distinguish beyond 46+ years old. Our study stresses the usefulness of a large-scale application of the Falys-Prangle-method, which will increase the visibility of mature adults, especially in archaeological burnt human skeletal collections, where such information is, at present, extremely difficult to obtain.
Trends in Plant Science
In the USA, 100 000 people go missing every year. Difficulty in the rapid identification of sites... more In the USA, 100 000 people go missing every year. Difficulty in the rapid identification of sites of human decomposition complicates the recovery of bodies, especially in forests. We propose that spectral responses in tree and shrub canopies could act as guides to find cadavers using remote sensing platforms for societal benefit.
American Journal of Physical Anthropology
OBJECTIVES This study aims to increase the rate of correctly sexed calcined individuals from arch... more OBJECTIVES This study aims to increase the rate of correctly sexed calcined individuals from archaeological and forensic contexts. This is achieved by evaluating sexual dimorphism of commonly used and new skeletal elements via uni- and multi-variate metric trait analyses. MATERIALS AND METHODS Twenty-two skeletal traits were evaluated in 86 individuals from the William M. Bass donated cremated collection of known sex and age-at-death. Four different predictive models, logistic regression, random forest, neural network, and calculation of population specific cut-off points, were used to determine the classification accuracy (CA) of each feature and several combinations thereof. RESULTS An overall CA of ≥ 80% was obtained for 12 out of 22 features (humerus trochlea max., and lunate length, humerus head vertical diameter, humerus head transverse diameter, radius head max., femur head vertical diameter, patella width, patella thickness, and talus trochlea length) using univariate analysis. Multivariate analysis showed an increase of CA (≥ 95%) for certain combinations and models (e.g., humerus trochlea max. and patella thickness). Our study shows metric sexual dimorphism to be well preserved in calcined human remains, despite the changes that occur during burning. CONCLUSIONS Our study demonstrated the potential of machine learning approaches, such as neural networks, for multivariate analyses. Using these statistical methods improves the rate of correct sex estimations in calcined human remains and can be applied to highly fragmented unburnt individuals from both archaeological and forensic contexts.
Forensic Anthropology
African Americans comprise approximately 13% of the U.S. population, 26% of missing persons, and ... more African Americans comprise approximately 13% of the U.S. population, 26% of missing persons, and 51% of homicide victims (Kochanek et al. 2019; National Crime Information Center [NCIC] 2018; U.S. Census Bureau 2010). However, African American remains are underrepresented in the documented skeletal samples resulting from body donations to U.S. taphonomic research facilities. If forensic anthropologists are to rise to the challenge of identifying remains from this segment of the U.S. population, and if heritable differences among human populations are to be distinguished from the embodied differences acquired by marginalized individuals, a deeper understanding of African American skeletal biology is essential. This understanding is contingent on Black donors participating in whole-body donation to anthropological research facilities—participation that may be undermined by a legacy of mistrust between Black communities and the traditionally White-dominated scientific and medical establ...
American Journal of Physical Anthropology, 2020
The Falys–Prangle-method assesses age-related morphological changes to the sternal clavicle end (... more The Falys–Prangle-method assesses age-related morphological changes to the sternal clavicle end (SCE), enabling the observation of mature adults from the 5th decade onwards in unburnt human skeletal remains. The aim of this study is to investigate the applicability of the Falys–Prangle-method on burnt human remains.
American Journal of Physical Anthropology, 2021
This study aims to increase the rate of correctly sexed calcined individuals from archaeological ... more This study aims to increase the rate of correctly sexed calcined individuals from archaeological and forensic contexts. This is achieved by evaluating sexual dimorphism of commonly used and new skeletal elements via uni- and multi-variate metric trait analyses.
Proceedings of the AAAI Conference on Artificial Intelligence
Large collections of images, if curated, drastically contribute to the quality of research in man... more Large collections of images, if curated, drastically contribute to the quality of research in many domains. Unsupervised clustering is an intuitive, yet effective step towards curating such datasets. In this work, we present a workflow for unsupervisedly clustering a large collection of forensic images. The workflow utilizes classic clustering on deep feature representation of the images in addition to domain-related data to group them together. Our manual evaluation shows a purity of 89% for the resulted clusters.
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Papers by Dawnie Steadman