Temporal mapping of the closure of the anterior fontanelle and contiguous sutures using computed tomography, in silico models of modern infants.

The aim of this study is to quantify and statistically model the age-related decline in the fibrous connective tissue interface of the anterior fontanelle in modern Australian infants, using three-dimensional, semi-automated computed-assisted design protocols. Non-linear regression with variance models, using power functions, combined with quantile regression of the 5th and 95th population percentiles, were utilised to assess absolute anterior fontanelle surface area (AFSA) as a function of age, using multi-slice cranial computed tomography scans obtained from 256 infants aged < 30 months (males: n = 126, females: n = 109) from Brisbane children's hospitals. Normalised AFSA (NFSA), standardised for variation in cephalic size, followed a progressive decline from birth, the greatest velocity change occurring between the 3-6 and 6-9 month cohorts. Growth of the neurocranium is the most significant within the first 8 months postpartum, with a mean increase of 19.03 mm in maximum cranial length and 10.04 mm in breadth. Directionality of fontanelle closure, quantified using spline curves refutes fundamental assumptions that the anterior fontanelle is consistent with a quadrilateral, and contiguous sutures exhibit constant velocity of closure. The present study provides normative values for fontanelle size and diameters as well as new predictive non-linear models for age substantiation, screening of developmental abnormalities and indicators of suspected child maltreatment in modern infants aged birth to 30 months.

Introducing Computed Tomography Standards for Age Estimation of Modern Australian Subadults Using Postnatal Ossification Timings of Select Cranial and Cervical Sites(.).

Contemporary, population-specific ossification timings of the cranium are lacking in current literature due to challenges in obtaining large repositories of documented subadult material, forcing Australian practitioners to rely on North American, arguably antiquated reference standards for age estimation. This study assessed the temporal pattern of ossification of the cranium and provides recalibrated probabilistic information for age estimation of modern Australian children. Fusion status of the occipital and frontal bones, atlas, and axis was scored using a modified two- to four-tier system from cranial/cervical DICOM datasets of 585 children aged birth to 10 years. Transition analysis was applied to elucidate maximum-likelihood estimates between consecutive fusion stages, in conjunction with Bayesian statistics to calculate credible intervals for age estimation. Results demonstrate significant sex differences in skeletal maturation (p < 0.05) and earlier timings in comparison with major literary sources, underscoring the requisite of updated standards for age estimation of modern individuals.

Ontogeny of the spheno-occipital synchondrosis in a modern Queensland, Australian population using computed tomography.

Due to disparity regarding the age at which skeletal maturation of the spheno-occipital synchondrosis occurs in forensic and biological literature, this study provides recalibrated multislice computed tomography (MSCT) age standards for the Australian (Queensland) population, using a Bayesian statistical approach. The sample comprises retrospective cranial/cervical MSCT scans obtained from 448 males and 416 females aged birth to 20 years from the Skeletal Biology and Forensic Anthropology Research Osteological Database. Fusion status of the synchondrosis was scored using a modified six-stage scoring tier on an MSCT platform, with negligible observer error (κ = 0.911 ± 0.04, intraclass correlation coefficient = 0.994). Bayesian transition analysis indicates that females are most likely to transition to complete fusion at 13.1 years and males at 15.6 years. Posterior densities were derived for each morphological stage, with complete fusion of the synchondrosis attained in all Queensland males over 16.3 years of age and females aged 13.8 years and older. The results demonstrate significant sexual dimorphism in synchondrosis fusion and are suggestive of intrapopulation variation between major geographic regions in Australia. This study contributes to the growing repository of contemporary anthropological standards calibrated for the Queensland milieu to improve the efficacy of the coronial process for medicolegal death investigation. As a stand-alone age indicator, the basicranial synchondrosis may be consulted as an exclusion criterion when determining the age of majority that constitutes 17 years in Queensland forensic practice.

Effect of broadcast baiting on abundance patterns of red imported fire ants (Hymenoptera: Formicidae) and key local ant genera at long-term monitoring sites in Brisbane, Australia.

In 2001, the red imported fire ant (Solenopsis invicta Buren) was identified in Brisbane, Australia. An eradication program involving broadcast bait treatment with two insect growth regulators and a metabolic inhibitor began in September of that year and is currently ongoing. To gauge the impacts of these treatments on local ant populations, we examined long-term monitoring data and quantified abundance patterns of S. invicta and common local ant genera using a linear mixed-effects model. For S. invicta, presence in pitfalls reduced over time to zero on every site. Significantly higher numbers of S. invicta workers were collected on high-density polygyne sites, which took longer to disinfest compared with monogyne and low-density polygyne sites. For local ants, nine genus groups of the 10 most common genera analyzed either increased in abundance or showed no significant trend. Five of these genus groups were significantly less abundant at the start of monitoring on high-density polygyne sites compared with monogyne and low-density polygyne sites. The genus Pheidole significantly reduced in abundance over time, suggesting that it was affected by treatment efforts. These results demonstrate that the treatment regime used at the time successfully removed S. invicta from these sites in Brisbane, and that most local ant genera were not seriously impacted by the treatment. These results have important implications for current and future prophylactic treatment efforts, and suggest that native ants remain in treated areas to provide some biological resistance to S. invicta.

Evaluation of the Suchey-Brooks method of age estimation in an Australian subpopulation using computed tomography of the pubic symphyseal surface.

Despite the prominent use of the Suchey-Brooks (S-B) method of age estimation in forensic anthropological practice, it is subject to intrinsic limitations, with reports of differential interpopulation error rates between geographical locations. This study assessed the accuracy of the S-B method to a contemporary adult population in Queensland, Australia and provides robust age parameters calibrated for our population. Three-dimensional surface reconstructions were generated from computed tomography scans of the pubic symphysis of male and female Caucasian individuals aged 15-70 years (n = 195) in Amira and Rapidform. Error was analyzed on the basis of bias, inaccuracy and percentage correct classification for left and right symphyseal surfaces. Application of transition analysis and Chi-square statistics demonstrated 63.9 and 69.7% correct age classification associated with the left symphyseal surface of Australian males and females, respectively, using the S-B method. Using Bayesian statistics, probability density distributions for each S-B phase were calculated, providing refined age parameters for our population. Mean inaccuracies of 6.77 (±2.76) and 8.28 (±4.41) years were reported for the left surfaces of males and females, respectively; with positive biases for younger individuals (<55 years) and negative biases in older individuals. Significant sexual dimorphism in the application of the S-B method was observed; and asymmetry in phase classification of the pubic symphysis was a frequent phenomenon. These results recommend that the S-B method should be applied with caution in medico-legal death investigations of Queensland skeletal remains and warrant further investigation of reliable age estimation techniques.