L' étude réalisée s'est portée sur la détermination de l’âge à partir d’investigations sur l’alvéolyse humaine.Le manque de fiabilité de l’attache épithéliale comme indicateur d’âge et l’absence de corrélation de la translucidité dentinaire sur dents entières ou coupées ont démontré l'intérêt d'un nouveau modèle odontologique d'estimation de l'âge. Nous avons, pour cela, , recruté une série importante de scanners (500)à visée implantaire assortis d’un questionnaire médico-administratif administré en face à face. Une base équilibrée en terme de sex-ratio et de classes d’âge a été constituée avec comme critère d’inclusion des secteurs dentés et observables. La deuxième phase a consisté à pratiquer des mesures biométriques de la hauteur de perte d’os alvéolaire par rapport au référent classique que constitue la jonction émail Cément. A partir des données relevées, et ajustées sur les variables individuelles et comportementales recueillies dans le questionnaire, nous avons établi une corrélation avec la variable continue, l’âge. Nous avons pu proposer un modèle d’estimation de l’âge alternatif à celui de la méthode odontologique de Lamendin avec une fiabilité identique mais applicable sur des classes d’âges de 25 à 60 ans.Cette méthode a été validée par une étude comparative de trois indicateurs d'erreurs et la formule optimisée par la méthode Bootstrap. Les modèles ont été, ensuite, appliqués sur une série de crânes anciens complets (32) et sur une population contemporaine (50). Enfin, nous avons ouvert la perspective ,à partir du même protocole, d'estimation de l'alvéolyse à partir de l'âge ajusté ou non sur les différentes variables retenues dans l'étude principale. / The study carried out concerned to the determination of the age from investigations on the human alveolar bone loss. The lack of reliability of the tie epithelial as indicator of age and the absence of correlation of the transparency of the dentin on whole or cut teeth demonstrated the interest of a new odontological model of estimation of the age. We have, for it, recruited an important series of scanners (500) for implantological treatment matched by a medical administrative questionnaire administered opposite to face. A base balanced in term of sex-ratio and age groups was established with as criterion of inclusion of the toothed and observable sectors. The second phase consisted in practicing biometric measures of the height of loss of alveolar bone with regard to the classic referent that the junction enamel Cement establishes .From the data, and adjusted on the individual and behavioral variables collected in the questionnaire, we established a correlation with the continuous variable, the age. We were able to propose a model of estimation of the age in that of the odontological method of Lamendin with an identical but applicable reliability on age groups from 25 to 60 years. This method was validated by a comparative study of three indicators of errors and the formula optimized by the Bootstrap method. The models were, then, applied to a series of ancient complete skulls (32) and to a contemporary population (50). Finally, we opened the prospect, from the same protocol, from the estimation of the alveolar bone loss from the adjusted age or not on the various variables held) in the main study.

L’âge est un paramètre du profil biologique des individus immatures que l’on peut estimer de manière suffisamment fiable et précise. Les méthodes utilisées ne respectent pas toutes des critères méthodologiques valides et sont donc relativement critiquables. Une analyse de 256 méthodes utilisées en anthropologie biologique a qualifié et quantifié les biais et limites de construction et d’application et propose une classification objective des méthodes mettant en évidence celles qui sont valides. Cette analyse a servi à élaborer le protocole d’une nouvelle méthode standardisée. Les surfaces de l’os iliaque, la cinquième vertèbre lombaire et la clavicule ont été reconstruites à partir de CT scans avec le logiciel AVIZO®. Des variables biométriques et non-biométriques ont été obtenues sur ces trois os. Des équations non-paramétriques de type Multivariate Adaptive Regression Splines (MARS) prédisant l’âge à partir des variables ont été calculées avec le logiciel statistique R®. Les variables iliaques, les hauteurs latérales vertébrales et la longueur maximale de la clavicule ont donné les meilleures prédictions de l’âge. Aucune différence significative entre les âges réels et estimés n'a été observée sur trois échantillons-test de Marseille, Toulouse et la collection ostéologique Luis Lopes. Les résultats sont meilleurs ou comparables à ceux d’autres méthodes. Des probabilités d’âge en fonction des indicateurs non-biométriques ont donné des résultats suffisamment fiables, mais pas assez précis pour être valides. Notre méthode d’estimation de l’âge a 95% de fiabilité et 90% de justesse. Elle est statistiquement valide et utilisable en contexte médico-légal et archéologique. / Age is one of the parameters of a juvenile biological profile that can be estimated with sufficient reliability and precision. Many juvenile age estimation methods do not follow valid methodological criteria. A critical analysis of 256 methods used in physical anthropology was done to qualify and quantify biases and limitations of method construction and application. An objective and practical classification of methods highlighting those respecting valid sampling protocols and statistical criteria was constructed. This analysis provided a protocol for a new standardised juvenile age estimation method. Surfaces of the iliac bone, fifth lumbar vertebra and clavicle were reconstructed from CT scans of individuals from Marseilles using the AVIZO® software. Biometric growth variables and non-biometric maturation indicators were taken on the three bones. Non-parametric Multivariate Adaptive Regression Splines (MARS) models were calculated with the R® software to predict age using the variables. The best models were obtained with variables of the ilium, left and right vertebral heights and maximal clavicular length. These models were validated on three samples from Marseilles, Toulouse and the Luis Lopes osteological collection. They were comparable or better than other age estimation methods. Posterior probabilities of age were calculated using maturation stages of four iliac epiphyses. Results were reliable, but precision was too low for validation. Our new juvenile age estimation method can predict age with 95% reliability and 90% accuracy. It is standardised, statistically valid, integrates changes in variability and is applicable in a forensic or bioarchaeological context.

Histological methods to estimate skeletal age at death, in forensic cases, are an alternative to the more traditional gross morphological methods. Most histological methods utilize counts of bone type within a given field for their estimation. The method presented in this paper uses the percentage area occupied by unremodeled bone to estimate age. The percentage area occupied by unremodeled bone is used in a linear regression model to predict skeletal age at death. Additionally, this method uses digital software to measure area rather than the traditional technique in which a gridded microscope is used to estimate area. The clavicle was chosen as a sample site since it is not a weight bearing bone and has little muscular insertion. These factors reduce the variation seen as a result of differences in lifestyle or activity pattern.

Transition analysis transforms skeletal traits with an invariant, unidirectional series of stages into a likelihood function with a maximum likelihood value and a 95% confidence interval. Boldsen et al. used transition analysis to develop an adult age estimation method employing components of the cranial sutures, pubic symphysis and ilial portion of the sacroiliac joint, used either in combination or individually. This validation study aimed to use the 36 transition analysis numerical, categorical scores for the anatomical features in conjunction with the ADBOU computer program to assess the accuracy and precision of the age estimates for 149 black individuals from the Pretoria Bone Collection. In addition, the effect of observer variability in scoring of these traits was assessed. Six age estimations were generated by the ADBOU computer program using 1) the cranial sutures only, 2) the pubic symphysis only, 3) the auricular surface of the ilium only, 4) all three features combined, 5) all three features combined and modified by a forensic prior distribution and 6) all three features combined and modified by an archaeological prior distribution. The six point estimate categories, calculated from the maximum likelihood values, were evaluated for accuracy using mean absolute values. The 95% confidence intervals were evaluated for range width and accuracy. Cohen’s Kappa statistics were used to analyse repeatability of the scoring procedure through inter- and intra-observer agreement and Kruskal-Wallis ANOVA statistics to determine the effect of observer differences on the final age estimates. The usefulness of the age ranges were diminished by large widths encompassing up to 95 years. The accuracy for the point estimates fared better for the combined skeletal indicators and overall accuracy was improved by using the archaeological prior distribution. The archaeological prior distribution was also responsible for narrowing the age ranges, especially in the older ages (over 70 years). Age estimates did not differ significantly when using inter- and intra-observer scores, but experience with the method did seem to improve results. Overall, age ranges were too wide, but accuracy could potentially be improved by adding more skeletal components to the method and using a population-specific prior distribution. The method would need considerable adjustments to make it usable in a South African setting. / Dissertation (MSc)--University of Pretoria, 2014. / tm2015 / Anatomy / MSc / Unrestricted

Big sagebrush (Artemisia tridentata Nutt.) is the most widespread and common shrub in the sagebrush biome of western North America. Of the three most common subspecies of big sagebrush (Artemisia tridentata), mountain big sagebrush (ssp. vaseyana; MBS) is the most resilient to disturbance, but still requires favorable climactic conditions and a viable post-fire seedbank for successful unassisted recovery. This study was designed to assess MBS seed production throughout post-fire recovery. We performed 2 pilot studies to develop methods for estimating seed production and plant age. The results of the pilot studies and a space-for-time substitution strategy were used to measure seed production on 13 sites ranging from 10-33 years post-fire. We hypothesized that seed rain (mean seeds produced/ m2) would peak before stand density had maximized due to decreasing individual plant fecundity (mean seeds produced/ plant) in high density stands. We measured population density and individual plant fecundity for three size classes of MBS and used forward stepwise regression analysis to identify environmental factors influencing seed production over time. Density for small (basal stem diameter (BSD) <1 cm) and medium-sized (BSD=1-3 cm) plants was consistently low and was not affected by time since fire (TSF), while large-sized (BSD > 3 cm) plant density increased steadily with TSF (p=0.0002). Plant fecundity decreased with TSF for all three size classes (p range = 0.019 – 0.0506), with large plants dominating reproductive output. Small and medium-sized plant fecundity was negatively correlated with winter precipitation (p range = 0.0106-0.0174), while large plant fecundity was positively correlated with winter precipitation (p<0.0001) and negatively correlated with elevation (p=0.0001). Despite losses in plant fecundity over time for all size classes, steady recruitment in population density resulted in increased seed rain (p=0.0039), suggesting that increases in stand density compensated for losses in individual plant fecundity. Results partially support our hypothesis that the time required for MBS seed rain to be maximized was not tightly bound to indicators of stand maturation. Understanding the factors that influence post-fire seed production can help land managers better manage for successful recovery by providing them with tools for evaluating seed production capabilities of MBS communities.

Accurate estimates of parameters and demographic rates of wildlife populations are crucial to management and conservation. One parameter of interest is age because it influences multiple demographic rates and behaviors including reproduction, dispersal, migration, and disease transmission. There are a number of methods used to estimate ages of wildlife. One of the most common methods used for mammals is evaluation of patterns in dental eruption and tooth wear. In the first chapter, we evaluate the accuracy associated with estimates of age from dental eruption and patterns of tooth wear for mule deer (Odocoileus hemionus). In the second chapter, we use age estimates validated within the first chapter to explore how age and other maternal factors may influence number of offspring born per litter in mule deer. We further test relative support for two common hypotheses--terminal investment and reproductive restraint--regarding the relationship between age and reproductive investment in this species. Our results will inform conservation, management, and research efforts associated with mule deer.

No description available.

Exploration of the internal structures of teeth is complex and has the potential to add greatly to existing information about the lifecourse of archaeological individuals, but has yet to realize its full interpretative value as an avenue of bioarchaeological inquiry. This thesis consists of three papers that focus on the potential for internal dental structures to provide important information on chronological age, and physiological alterations linked to vitamin D deficiency. The first paper used SEM, microscopic imaging, and histological investigation of tooth dentin to determine the presence of mineralisation defects, observed as interglobular dentin (IGD) (spaces following incremental lines) in living (with known medical history) and archaeological individuals with clear healed rickets. This paper demonstrated that incremental bands of IGD are indicative of vitamin D deficiency. The second paper expands identification of those with deficiency by quantifying morphological changes in pulp chambers of living and archaeological individuals. Pulp chambers were radiographed, evaluated histologically, and measured. Those with evidence of past vitamin D deficiency displayed constricted or chair shaped pulp horns. This radiographic technique provides a non-destructive tool to identify individuals that experienced childhood vitamin D deficiency. The role vitamin D plays in the development of IGD over the lifecourse requires that accurate age estimates be conducted on older as well as younger adults. The third paper used a new version of pulp/tooth area ratios to provide an accurate estimation of age-at-death in older adults (50+). ImageJ software was used to calculate areas on sectioned teeth and results provided a mean absolute error (MAE) of ±3.9 years in older adults. The results described in this thesis contribute to broader topics of discussion in anthropology, such as investigating health and metabolic disease in human populations, and adds to the ongoing discussion and evaluation of age-at-death techniques used to extend our ability to study the lifecourse of archaeological individuals. / Dissertation / Doctor of Philosophy (PhD) / Teeth record life events and the three papers in this thesis use dental structures to provide methodological foundations to evaluate the occurrence and severity of vitamin D deficiency in early life. The potential long-term consequences of such events are investigated through accurate recognition of older adults. Vitamin D regulates skeletal health by mediating calcium absorption and phosphorous homeostasis and deficiency is recognised as an important health concern. Accurate identification of older adults is also a widely recognised problem in skeletal studies. Age-at-death estimation in older individuals was calculated and the exploration of abnormal pulp chamber shape and mineralisation defects in tooth dentin was done to determine vitamin D status in both younger and older individuals. This research established that internal dental structures enables past episodes of vitamin D deficiency to be recognized in cases where skeletal indicators are not clear and permits increased precision in age-at-death estimations in the older individual.

Yes / Age and gender classification are two important problems that recently gained popularity in the research community, due to their wide range of applications. Research has shown that both age and gender information are encoded in the face shape and texture, hence the active appearance model (AAM), a statistical model that captures shape and texture variations, has been one of the most widely used feature extraction techniques for the aforementioned problems. However, AAM suffers from some drawbacks, especially when used for classification. This is primarily because principal component analysis (PCA), which is at the core of the model, works in an unsupervised manner, i.e., PCA dimensionality reduction does not take into account how the predictor variables relate to the response (class labels). Rather, it explores only the underlying structure of the predictor variables, thus, it is no surprise if PCA discards valuable parts of the data that represent discriminatory features. Toward this end, we propose a supervised appearance model (sAM) that improves on AAM by replacing PCA with partial least-squares regression. This feature extraction technique is then used for the problems of age and gender classification. Our experiments show that sAM has better predictive power than the conventional AAM.

The present study investigates the impact of northern pike (Esox Lucius) on the growth of juvenile burbot (Lota lota) in northern lake ecosystems. It is hypothesized that the presence of pike will positively affect the growth of juvenile burbot by reducing interspecific competition and increasing the abundance of benthic invertebrates. To test this hypothesis, electrofishing for juvenile burbot was conducted in the littoral zones of lakes with and without pike in the region Jämtland Härjedalen, Sweden. Data on length and age of the captured burbot were used to compare growth between the two lake types. Contrary to the initial hypothesis, the results show that juvenile burbot were significantly larger at a given age in lakes where pike was absent. This outcome suggests that juvenile burbot may reduce their foraging activity in lakes with pike to minimize predation risk. Since adult burbot has shown to be of greater size in lakes with pike, future research could investigate whether the shift towards piscivory in burbot leads to changes in how they are affected by pike.