Validation of age determination using otoliths of the European anchovy (Engraulis encrasicolus L.) in the Bay of Biscay

Validation of the age determination procedure using otoliths of European anchovy in the Bay of Biscay was achieved by monitoring very strong year-classes in successive spring catches and surveys, as well as the seasonal occurrence of edge types. Historical corroboration of the ageing method was obtained by cross-correlation between successive age groups by year-classes in catches and surveys (1987–2013). Summary annual growth in length is also presented. Yearly annuli consist of a hyaline zone (either single or composite) and a wide opaque zone, disrupted occasionally by some typical checks (mainly at age-0 and age-1 at peak spawning time). Age determination, given a date of capture, requires knowledge of the typical annual growth pattern of otoliths, their seasonal edge formation by ages and the most typical checks. Most opaque growth occurs in summer and is minimal (translucent) in winter. Opaque zone formation begins earlier in younger fish (in spring), and this helps distinguish age-1 from age-2+.

Image quality assessment and medical physics evaluation of different portable dental X-ray units

Introduction: Recently developed portable dental X-ray units increase the mobility of the forensic odontologists and allow more efficient X-ray work in a disaster field, especially when used in combination with digital sensors. This type of machines might also have potential for application in remote areas, military and humanitarian missions, dental care of patients with mobility limitation, as well as imaging in operating rooms. Objective: To evaluate radiographic image quality acquired by three portable X-ray devices in combination with four image receptors and to evaluate their medical physics parameters. Materials and methods: Images of five samples consisting of four teeth and one formalin-fixed mandible were acquired by one conventional wall-mounted X-ray unit, MinRay (R) 60/70 kVp, used as a clinical standard, and three portable dental X-ray devices: AnyRay (R) 60 kVp, Nomad (R) 60 kVp and Rextar (R) 70 kVp, in combination with a phosphor image plate (PSP), a CCD, or a CMOS sensor. Three observers evaluated images for standard image quality besides forensic diagnostic quality on a 4-point rating scale. Furthermore, all machines underwent tests for occupational as well as patient dosimetry. Results: Statistical analysis showed good quality imaging for all system, with the combination of Nomad (R) and PSP yielding the best score. A significant difference in image quality between the combination of the four X-ray devices and four sensors was established (p < 0.05). For patient safety, the exposure rate was determined and exit dose rates for MinRay (R) at 60 kVp, MinRay (R) at 70 kVp, AnyRay (R), Nomad (R) and Rextar (R) were 3.4 mGy/s, 4.5 mGy/s, 13.5 mGy/s, 3.8 mGy/s and 2.6 mGy/s respectively. The kVp of the AnyRay (R) system was the most stable, with a ripple of 3.7%. Short-term variations in the tube output of all the devices were less than 10%. AnyRay (R) presented higher estimated effective dose than other machines. Occupational dosimetry showed doses at the operator`s hand being lowest with protective shielding (Nomad (R): 0.1 mu Gy). It was also low while using remote control (distance > 1 m: Rextar (R) < 0.2 mu Gy, MinRay (R) < 0.1 mu Gy). Conclusions: The present study demonstrated the feasibility of three portable X-ray systems to be used for specific indications, based on acceptable image quality and sufficient accuracy of the machines and following the standard guidelines for radiation hygiene. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Comparisons between bone and cementum compositions and the possible basis for their layered appearances

In humans, age estimation from the adult skeleton represents an attempt to determine chronological age based on growth and maturational events. In teeth, such events can be characterized by appositional growth layers in midroot cementum. The purpose of this study was to determine the underlying cause of the layered microstructure of human midroot cementum. Whether cementum growth layers are caused by changes in relative mineralization, collagen packing and/or orientation, or by variations in organic matrix apposition was investigated by subjecting midroot sections of human canine teeth to analysis using polarized light and scanning electron microscopy (SEM). Polarized light was used to examine transverse midroot sections in both mineralized and demineralized states. Mineralized sections were also reexamined following subsequent decollagenization. Polarized light was additionally used in the examination of mineralized sections taken transversely, longitudinally, and obliquely from the same tooth root. From the birefringence patterns it was concluded that collagen orientation does not change with varying section plane. Instead, the mineral phase was most responsible for the birefringence of the cementum. SEM studies suggested that neither collagen packing nor collagen orientation change across the width of the cementum, confirming and validating the results of the polarized light examination. Also, SEM analysis using electron backscatter and the electron probe suggested no changes in the mean atomic number density, calcium, phosphate, and sulfur levels across the width of the cementum. Therefore, we conclude that crystalline orientation and/or size is responsible for the layered appearance of cementum. (Bone 30:386-392; 2002) (C) 2002 by Elsevier Science Inc. All rights reserved.

Virtual anthropology: A comparison between the performance of conventional X-ray and MDCT in investigating the trabecular structure of long bones.

Recently, modern cross-sectional imaging techniques such as multi-detector computed tomography (MDCT) have pioneered post mortem investigations, especially in forensic medicine. Such approaches can also be used to investigate bones non-invasively for anthropological purposes. Long bones are often examined in forensic cases because they are frequently discovered and transferred to medico-legal departments for investigation. To estimate their age, the trabecular structure must be examined. This study aimed to compare the performance of MDCT with conventional X-rays to investigate the trabecular structure of long bones. Fifty-two dry bones (24 humeri and 28 femora) from anthropological collections were first examined by conventional X-ray, and then by MDCT. Trabecular structure was evaluated by seven observers (two experienced and five inexperienced in anthropology) who analyzed images obtained by radiological methods. Analyses contained the measurement of one quantitative parameter (caput diameter of humerus and femur) and staging the trabecular structure of each bone. Preciseness of each technique was indicated by describing areas of trabecular destruction and particularities of the bones, such as pathological changes. Concerning quantitative parameters, the measurements demonstrate comparable results for the MDCT and conventional X-ray techniques. In contrast, the overall inter-observer reliability of the staging was low with MDCT and conventional X-ray. Reliability increased significantly when only the results of the staging performed by the two experienced observers were compared, particularly regarding the MDCT analysis. Our results also indicate that MDCT appears to be better suited to a detailed examination of the trabecular structure. In our opinion, MDCT is an adequate tool with which to examine the trabecular structure of long bones. However, adequate methods should be developed or existing methods should be adapted to MDCT.

A contribution to the study of post-depositional alterations of pottery using TL dating analysis

In luminescence dating, the potassium concentration significantly contributes to the dose rate value in the age estimation. Within this study, fine-grain thermoluminescence dating has been applied on sherds of calcareous pottery of known age, excavated at a Roman site in Mallorca, Spain. For those of the samples that showed signs of severe potassium leaching, according to chemical and mineralogical examination, the thermoluminescence analysis provided overestimated dates. By using the known archaeological age of the samples, a corrected dose rate value can be estimated which provides the potassium concentration averaged for the burial period. Finally, a step-like model can then be used to estimate the fraction of the burial period after which most of the alteration effects took place.

A test of Suchey-Brooks (pubic symphysis) and Buckberry-Chamberlain (auricular surface) methods on an identified Spanish sample: paleodemographic implications

Forensic Anthropology and Bioarchaeology studies depend critically on the accuracy and reliability of age-estimation techniques. In this study we have evaluated two age-estimation methods for adults based on the pubic symphysis (Suchey-Brooks) and the auricular surface (Buckberry-Chamberlain) in a current sample of 139 individuals (67 women and 72 men) from Madrid in order to verify the accuracy of both methods applied to a sample of innominate bones from the central Iberian Peninsula. Based on the overall results of this study, the Buckberry-Chamberlain method seems to be the method that provides better estimates in terms of accuracy (percentage of hits) and absolute difference to the chronological age taking into account the total sample. The percentage of hits and mean absolute difference of the Buckberry-Chamberlain and Suchey-Brooks methods are 97.3% and 11.24 years, and 85.7% and 14.38 years, respectively. However, this apparently greater applicability of the Buckberry-Chamberlain method is mainly due to the broad age ranges provided. Results indicated that Suchey-Brooks method is more appropriate for populations with a majority of young individuals, whereas Buckberry-Chamberlain method is recommended for populations with a higher percentage of individuals in the range 60-70 years. These different age estimation methodologies significantly influence the resulting demographic profile, consequently affecting the biological characteristics reconstruction of the samples in which they are applied.

Determinação da idade dental de crianças brasileiras nordestinas: novos valores de conversão de maturidade dental para população específica

Since Demirjian's system of estimating dental maturity was first described, many researchers from different countries have tested its accuracy among diverse populations. Some of these studies have pointed out a need to determine population-specific standards. In Brazil, the Northeast region is the one that most suffers the negative impact of exodus, specially related to the increase of abandoned children in the cities. The aim of this study was to test the accuracy of Demirjian's system for assessing the dental maturity of northeastern Brazilian children, so as to present a scale for maturity score conversion into dental age developed specifically for this population. This could be used for forensic, anthropological and legal matters, and also as a model for other countries attempting to formulate their own conversion scales. Panoramic radiographs of 1,491 children (821 females and 670 males), aged 7 to 13 years, from Ceará state, northeast Brazil, were assessed by a single observer to determine dental age (DA) according to Demirjian's system. The mean percentage of intra-observer agreement was 86.6%, with a mean Cohen's Kappa coefficient of 0.67 (substantial agreement). The DA was compared by paired t-test to subjects' chronological age (CA). The differences between CA and DA in all age groups were statistically significant (p<0.0001), demonstrating a great advancement in DA among Brazilians. Scatter plots were drawn for both genders, and the data were fitted to a growth curve, y = 100/ (1 + e-a(x b)). Graphs corresponding to the 50th percentile curves were produced. A table with new values for the conversion of maturity score into dental age for northeastern Brazilian children is presented. The great advancement in DA, as obtained by Demirjian's system in this population, justified the determination of specific scores for dental maturity assessment

Dental fluorescence: Potential forensic use

In cases of identification of bones, skeletal segments or isolated bones, searching for biotypologic diagnostic data to estimate an individual's age enables comparing these data with those of missing individuals. Enamel, dentin and pulp undergo remarkable changes during an individual's life. The enamel becomes more mineralized, smoother and thinner, and deteriorates because of physiological and pathological factors. Dental pulp decreases in volume due to the deposition of secondary dentin; thus, the dentin becomes thicker with time. In natural teeth, the fluorescence phenomenon occurs in dentin and enamel and changes in those tissues may alter the expression of the natural tooth color. The aim of this study was to assess the correlation between age and teeth fluorescence for individuals from different age groups. The sample consisted of 66 randomly selected Brazilians of both genders aged 7-63 years old. They were divided into 6 groups: Group 1 - aged 7-12 years, Group 2 - aged 13-20 years, Group 3 - aged 21-30 years, Group 4 - aged 31-40 years, Group 5 - aged 41-50 years and Group 6 - aged between 51 and 63 years. Upper right or left central incisors were used for the study. Restored and aesthetic rehabilitated teeth were excluded from the sample. The measurement of tooth fluorescence was carried out via computer analysis of digital images using the software ScanWhite DMC/Darwin Systems - Brazil. It was observed that dental fluorescence decreases when comparing the age groups 21-30, 31-40, 41-50 and 51-63 years. The results also showed that there is a statistically significant difference between the groups 41-50 years and 21-30 years (p=. 0.005) and also among the group 51-63 years and all other groups (p< 0.005). It can be concluded that dental fluorescence is correlated with age and has a similar and stable behavior from 7 to 20 years of age. It reaches its maximum expected value at the age of 26.5 years and thereafter decreases. © 2013 Elsevier B.V.

Evolutionary epigenetics of modern human populations

Epigenetic variability is a new mechanism for the study of human microevolution, because it creates both phenotypic diversity within an individual and within population. This mechanism constitutes an important reservoir for adaptation in response to new stimuli and recent studies have demonstrated that selective pressures shape not only the genetic code but also DNA methylation profiles. The aim of this thesis is the study of the role of DNA methylation changes in human adaptive processes, considering the Italian peninsula and macro-geographical areas. A whole-genome analysis of DNA methylation profile across the Italian penisula identified some genes whose methylation levels differ between individuals of different Italian districts (South, Centre and North of Italy). These genes are involved in nitrogen compound metabolism and genes involved in pathogens response. Considering individuals with different macro-geographical origins (individuals of Asians, European and African ancestry) more significant DMRs (differentially methylated regions) were identified and are located in genes involved in glucoronidation, in immune response as well as in cell comunication processes. A "profile" of each ancestry (African, Asian and European) was described. Moreover a deepen analysis of three candidate genes (KRTCAP3, MAD1L and BRSK2) in a cohort of individuals of different countries (Morocco, Nigeria, China and Philippines) living in Bologna, was performed in order to explore genetic and epigenetic diversity. Moreover this thesis have paved the way for the application of DNA methylation for the study of hystorical remains and in particular for the age-estimation of individuals starting from biological samples (such as teeth or blood). Noteworthy, a mathematical model that considered methylation values of DNA extracted from cementum and pulp of living individuals can estimate chronological age with high accuracy (median absolute difference between age estimated from DNA methylation and chronological age was 1.2 years).

Literature review of elasmobranch bycatch and retention rate

To address growing concern over the effects of fisheries non-target catch on elasmobranchs worldwide, the accurate reporting of elasmobranch catch is essential. This requires data on a combination of measures, including reported landings, retained and discarded non-target catch, and post-discard survival. Identification of the factors influencing discard vs. retention is needed to improve catch estimates and to determine wasteful fishing practices. To do this we compared retention rates of elasmobranch non-target catch in a broad subset of fisheries throughout the world by taxon, fishing country, and gear. A regression tree and random forest analysis indicated that taxon was the most important determinant of retention in this dataset, but all three factors together explained 59% of the variance. Estimates of total elasmobranch removals were calculated by dividing the FAO global elasmobranch landings by average retention rates and suggest that total elasmobranch removals may exceed FAO reported landings by as much as 400%. This analysis is the first effort to directly characterize global drivers of discards for elasmobranch non-target catch. Our results highlight the importance of accurate quantification of retention and discard rates to improve assessments of the potential impacts of fisheries on these species.

14C activity of Antarctic lichens

By the nuclear bomb tests during the 1950s and early 1960s, the radiocarbon content of the atmospheric CO, on the Southern Hemisphere rose within a few years from 98 to 162% of the standard recent value and then dropped to 122% (at the end of 1984). This rapid fluctuation was used to determine the lifetime of five species of lichens collected in the beginning of 1985 in the maritime Antarctic. Under the assumption that Lichens assimilate each year carbon at the same rate and that carbon once fixed at least in main branches never will be exchanged later on. The age of mature thalli of Caioplaco regalis, Ramalino tetebrata and Ustiea antarctica was determined to 32 years, while U, aurantiaco-atra and Himantormia lugubris gave an age of ca. 38 years and ca. 60 years, respectively.

Factors affecting female reproductive success and the survival of pouch young in the threatened brush-tailed rock-wallaby, Petrogale penicillata

Knowledge of factors affecting the survival of individuals and their reproductive success is essential for threatened species management, but studies assessing these factors are lacking for many threatened rock-wallaby species. In this study we investigated the factors influencing the breeding performance of females and the survival of pouch young in a wild colony of the threatened brush-tailed rock-wallaby. Individuals were trapped between October 2000 and April 2004. More than 50% of the females in the colony were breeding below their full potential and giving birth to only one offspring per year. Most females within the colony bred in synchrony, with a substantial birth peak evident during autumn. Pouch young born in autumn left the pouch during spring and were weaned during summer and autumn when forage was most abundant. Pouch young born during the autumn birth peak or in winter had a substantially higher probability of surviving through to pouch emergence than those born during spring or summer. This study provides demographic parameters that may be used in population models and for comparison with other populations, particularly those that are small and declining. To optimise reproductive success in reintroduction programs, females in good condition and with small pouch young should be released at the end of the wettest season.