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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

DNA Degradation as an Indicator of Post-Mortem Interval

Watson, William H. 08 1900 (has links)
The question of post-mortem interval (PMI) or time since death is often the most sought after piece of information associated with a medical death investigation. Based on the observation that DNA degradation disproportionately affects the analysis of larger genetic loci, it was proposed that DNA degradation, as a result of autolysis or putrefaction, could prove suitable as a potential rate-of-change indicator of PMI. Nine randomly amplified polymorphic DNA (RAPD) analysis primers and three sets of directed amplification primers were evaluated to determine their suitability for use in assessing the degree of DNA fragmentation in tissue samples. They were assessed for amplicon specificity, total DNA target sensitivity, allele monomorphism and the observance of degradation-based profile changes. Markers meeting the requisite criteria were then used to assess a range samples degraded under controlled and uncontrolled conditions. Tissue samples collected from seven domestic pigs (Sus scrofa) were incubated under controlled laboratory or uncontrolled field conditions to produce samples simulating those potentially collected in a forensic case. DNA samples isolated from these specimens were then analyzed at those loci which had been determined to meet the requisite criteria. Collectively, data generated from these analyses indicate that genetic profiles generated by this approach can provide information useful for estimating the post-mortem interval, with the locus and amplicons used being most useful during the first 72 hours after death.
2

Prediction of Post Mortem Interval from Degradation of Endogenous Nucleotides in Human Subjects

Williams, John Burgess 04 1900 (has links)
High Performance Liguid Chromatography was used to measure degradation of nucleotides in human cadavers for the purpose of prediction of post mortem interval. Endogenous nucleotides were extracted from integumentary tissue of six(6) human cadavers using six percent(6%) tricholoacetic acid. Linear regression statistical techniques were used to determine linearity of degradation of various nucleotide pools.
3

A molecular study of the forensically important calliphoridae (diptera) : implications and applications for the future of forensic entomology

Harvey, Michelle January 2006 (has links)
[Truncated abstract] A common application of forensic entomology is the estimation of post-mortem interval (PMI). This is most frequently estimated from the age of calliphorid specimens collected from a corpse, and in many cases it is the immature stages that are encountered. A critical step in the estimation of PMI is the accurate identification of insects to species level, with misidentification potentially resulting in the application of unsuitable developmental data and therefore inaccuracy in the resulting estimate. Identification has long been attempted on a morphological basis, but complicated by the lack of larval keys to the Calliphoridae, limited diagnostic features in immature stages and the poor preservation of specimens. Standard practice in forensic entomology is the rearing of immatures collected from the corpse through to the more distinctive adult stages, however this process is time-consuming and may be hindered where specimens die during rearing. Furthermore, many cases are presented for forensic entomologist as an afterthought and specimens are already preserved. Consequently, a new approach to the identification of calliphorids is sought which will overcome the problems of the morphological and rearing methods. ... The culmination of this study is the consideration of applications of molecular data to forensic entomology. A sequence-specific priming (SSP) technique is presented for the identification of the forensically significant calliphorids of Australia and New Zealand, along with a new method for the extraction and storage of calliphorid DNA samples using Whatman FTA cards. These techniques will potentially improve the efficiency and accuracy of identification in the estimation of PMI using calliphorids. The use of calliphorid DNA is not limited to PMI estimation, but may also be applied to museum studies. DNA was extracted from pupal casings from 300 year old mummified corpses, however difficulty was encountered in amplifying the DNA reproducibly. This illustrates however, the wide-ranging implications of the calliphorid sequence data gathered in this study. This thesis makes a significant contribution to the consideration of the status of some global calliphorid species. The new technique presented for identification of Australian and New Zealand species is the culmination of an important body of data that will ultimately contribute to the strong foundation of forensic entomology and our future accuracy, efficiency and utility as a routine investigative tool.
4

Nikdy neuskutečněný dialog mezi Heideggerem a Levinasem / Never realized dialogue between Heidegger and Levinas

Býmová, Zuzana January 2017 (has links)
Předkládaná práce je nesena snahou o zodpovězení otázky: V čem spočívá nesoulad filosofie? Nemůže být Lévinasova etika chápána jako doplnění Heideggerovy ontologie? Na zmíněné otázky je hledána odpověď prostřednictvím vpravení se do možného "dialogu" mezi Heideggerem a Lévinasem. Odlišné pojímání bytí u obou filosofů se odhalí nejenom jako možná příčina sporu, ale i jako důvod, kvůli kterému by nemohla být Lévinasova a Heideggerova filosofie nikdy komplementární. Lévinas na rozdíl od Heideggera, který je neustále na cestě bytí, bude rozvíjet veškerá svá témata na rovině "autrement qu'être", hranicemi bytí. Odlišný přístup k bytí se ukáže jako důvod, proč nemohou Heidegger Lévinasem při tematizování etiky, vztahu člověka se světem, smrti a času nalézt společnou řeč. Klíčová slova ět, smrt, čas
5

A preliminary investigation into the estimation of time since death from human skeletal remains by radioisotope and trace element analysis

Howard, Sheridan January 2008 (has links)
One of the first concerns for forensic anthropologists in dealing with skeletal remains in the Australian context is the determination of whether the remains are of anthropological, historical or archaeological interest. If fewer than 75 years have elapsed since death, remains are classified as anthropological and of forensic interest. However, an accurate and reliable method for estimating time since death (TSD) from human skeletal remains has thus far eluded forensic anthropologists. This study investigates the application in an Australian context of a novel approach proposed by Swift (2001) to dating skeletal remains from their contained levels of radioisotopes 210Po, 238U and 226Ra and trace elements. Radionuclide activity concentrations were determined using alpha and gamma spectrometry. Trace element concentrations were measured on three separate occasions using inductively coupled plasma mass spectrometry (ICP-MS). Discriminant analysis of the combination of activity concentration values for 210Po, 238U and 226Ra indicated the possibility of separation of bones derived from individuals who had died in the three eras of interest. Additionally, variations in the concentration levels of specific trace elements and certain inter-element relationships between elements also showed significant correlations with TSD. The study could not be exhaustive as access to human skeletal material was limited and additionally, the archaeological material had a different origin and post-death history to material from the more recent past. However, trend lines for inter-relationships between specific metals and for radionuclides indicated that all material fitted the same generally projected trends and as such, inferences with respect to variations of trace elements and radionuclides could be made with confidence. Bone radionuclide activity and calcium concentrations were all significantly higher in bones from the archaeological era than those from more recent eras, while trace lead concentrations contained in samples from the more recent historical era were significantly higher than those from other eras. Barium, lanthanum, rubidium, strontium, cerium and neodymium concentrations were all significantly correlated with one another and with radionuclide activity concentrations. Differences were found between the patterns of radionuclide activity and trace element concentrations between the skull and femur. The results of this study lend support to suggestions that multivariate analysis of trace element concentrations and radionuclide activity levels could aid in the estimation of time since death from skeletal remains in Australia. Although this study made use of only a limited amount of material, results clearly indicated the need to take into account variations arising from lifetime activities, diagenesis and bone type in applying the techniques to estimations of time since death. It highlights the need for a large-scale study using bone of known ages that systematically examines these influences on the estimation of time since death.
6

Estimating Postmortem Interval Using VNIR Spectroscopy on Human Cortical Bone

Servello, John A. 05 1900 (has links)
Postmortem interval (PMI) estimation is a necessary but often difficult task that must completed during a death investigation. The level of difficulty rises as time since death increases, especially with the case of skeletonized remains (long PMI). While challenging, a reliable PMI estimate may be of great importance for investigative direction and cost-savings (e.g. suspect identification, tailoring missing persons searches, non-forensic remains exclusion). Long PMI can be estimated by assessing changes in the organic content of bone (i.e. collagen), which degrades and is lost as the PMI lengthens. Visible-near infrared (VNIR) spectroscopy is one method that can be used for analyzing organic constituents, including proteins, in solid specimens. A 2013 preliminary investigation using a limited number of human cortical bone samples suggested that VNIR spectroscopy could provide a fast, reliable technique for assessing PMI in human skeletal remains. Clear separation was noted between "forensic" and "archaeological" specimen spectra within the near-infrared (NIR) bands. The goal of this research was to develop reliable multivariate classification models that could assign skeletal remains to appropriate PMI classes (e.g. "forensic" and "non-forensic"), based on NIR spectra collected from human cortical bone. Working with a large set of cortical samples (n=341), absorbance spectra were collected with an ASD/PANalytical LabSpec® 4 full range spectrometer. Sample spectra were then randomly assigned to training and test sets, where training set spectra were used to build internally cross-validated models in Camo Unscrambler® X 10.4; external validations of the models were then performed on test set spectra. Selected model algorithms included soft independent modeling of class analogy (SIMCA), linear discriminant analysis on principal components (LDA-PCA), and partial least squares discriminant analysis (PLSDA); an application of support vector machines on principal components (SVM-PCA) was attempted as well. Multivariate classification models were built using both raw and transformed spectra (standard normal variate, Savitzky-Golay) that were collected from the longitudinally cut cortical surfaces (Set A models) and the superficial cortical surface following light grinding (Set B models). SIMCA models were consistently the poorest performers, as were many of the SVM-PCA models; LDA-PCA models were generally the best performers for these data. Transformed-spectra model classification accuracies were generally the same or lower than corresponding raw spectral models. Set A models out-performed Set B counterparts in most cases; Set B models often yielded lower classification accuracy for older forensic and non-forensic spectra. A limited number of Set B transformed-spectra models out-performed the raw model counterparts, suggesting that these transformations may be removing scattering-related noise, leading to improvements in model accuracy. This study suggests that NIR spectroscopy may represent a reliable technique for assessing the PMI of unknown human skeletal remains. Future work will require identifying new sources of remains with established extended PMI values. Broadening the number of spectra collected from older forensic samples would allow for the determination of how many narrower potential PMI classes can be discriminated within the forensic time-frame.

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