Accurate Age Determination Research Articles

Intercalibration of the Servicio Nacional de Geología y Minería (SERNAGEOMIN), Chile and WiscAr 40Ar/39Ar laboratories for Quaternary dating

Accurate and precise dating of Quaternary lavas and pyroclastic flow or fall deposits is essential for understanding the evolution of active volcanoes and providing context for future eruptions and hazard assessment. The 40 Ar/ 39 Ar method is commonly employed to date these volcanic materials, however, dating young (<150 ka) K 2 O-poor materials can be challenging owing to low radiogenic 40 Ar* contents that can be difficult to distinguish from trapped atmospheric argon. To address this challenge, a collaborative intercalibration exercise involving the University of Wisconsin-Madison WiscAr Laboratory and the 40 Ar/ 39 Ar Laboratory of the Servicio Nacional de Geología y Minería (SERNAGEOMIN), Chile was conducted on a common set of samples with the aim of refining our methods and optimizing precision and accuracy of age determinations. Groundmass and plagioclase samples were analyzed on a 5-collector Noblesse ion counting mass spectrometer in the WiscAr lab, whereas measurements in the SERNAGEOMIN lab were performed using an ARGUS VI spectrometer equipped with faraday detectors and one compact discrete dynode electron multiplier. Samples for the intercalibration were collected jointly from three Andean Southern Volcanic Zone volcanoes to evaluate the capability of each laboratory to date different materials. Samples from lava flows with 1.0–3.2 wt % K 2 O from Planchon-Peteroa volcanic complex and with <1.0 wt % K 2 O from Calbuco Volcano that are the focus of ongoing geological studies were measured in both laboratories. Single crystals of plagioclase (0.6–1.0 wt% K 2 O) were measured from the voluminous Diamante (Pudahuel) ignimbrite sourced from the Diamante Caldera. Multiple rounds of experiments were conducted including co-irradiation of samples at Oregon State University, as well as irradiations using the CCHEN reactor in Chile to investigate differences in neutron fluence parameters. As a result, SERNAGEOMIN has modified long-used protocols for the CCHEN reactor so that Quaternary samples may be irradiated for periods of time most appropriate for their age. Although less precise than plateau ages, the isochron ages generated in the two laboratories agree at 2σ for each sample. Six of six co-irradiated samples from Planchon-Peteroa yield plateau ages that also show inter-lab agreement at 2σ. The low K 2 O lavas from Calbuco proved more challenging with only three out of five plateau ages in agreement between labs. SERNAGEOMIN blanks were higher and more variable in Calbuco experiments, thus, differences in the variability of the measured 36 Ar blanks between the two laboratories may explain the discrepancy in plateau ages. Analysis of single plagioclase crystals from the Diamante Ignimbrite show excellent agreement between labs for both weighted mean apparent ages and isochron ages. We favor an isochron age for the ignimbrite of 132.4 ± 2.2 ka, however, discrepancies in results between samples from three different outcrops present an interesting geochronologic problem that warrants further study. Overall, the consistency of the results between labs is promising. These new precise age determinations significantly improve our understanding of the temporal evolution of these active volcanoes. • Broad agreement of ages from tephras and lavas measured in two labs. • 40 Ar/ 39 Ar dating of low K 2 O lavas from Calbuco is challenging due to limited 40 Ar*. • We favor an isochron age of ∼132 ± 2 ka ka for the 270 km 3 Diamante Ignimbrite. • Care in sample preparation and irradiation, and control of blanks are essential.

Invited Commentary: Role of the Radiologist in Pregnancy-associated Cancer.

Invited Commentary: Role of the Radiologist in Pregnancy-associated Cancer.

A Critical Picture of Racism, Trophy Taking, and Forensics: Life Magazine May 22, 1944 “Picture of the Week”

Introduction: The 2020 American Urological Association (AUA) Retrospectroscope Award winning presentation investigated the history of war trophies. Included was Life magazine’s May 22, 1944 “Picture of the Week” showing a young American woman gazing at a skull sent by her boyfriend serving in the Pacific theater of WWII. The caption claimed the skull was from a Japanese soldier “picked up on a New Guinea beach.” The displaying of human remains so casually in a magazine brings up the ethical considerations behind how we use human remains in medicine, art, museums, and collections. Identification and interpretation of bony characteristics and injuries from skeletonized human remains can help demystify medical history, reconstruct battles, and bring identity back to the faceless. We investigated what forensic and paleopathology techniques can tell us about battlefield human remains including the Life skull. Sources and Methods: We reviewed the literature for information about the Life skull and characterization of physical traits and traumatic injuries that can be assessed from skeletal remains. Results: Taking ‘trophies’ from human remains has occurred throughout human history. Anatomical trophy taking by US troops in the Pacific during WWII was fueled by rampant jingoism and anti-Asian racism of the time. Battlefield methods to remove soft tissue from bone included boiling, skinning, scrubbing, lye, and ants. Similar techniques are used by modern medical examiners. The tropical Pacific climate and lack of burial would have hastened natural decomposition of a fallen soldier. The bony pelvis and the skull are the two most useful parts of the skeleton for assessment of human remains. The pelvis is the most reliable bone in the human body for determining sex, followed by the skull. The pelvis and skull also aid in the determination of age at death. Estimation of likely ancestry primarily relies on the skull but is a challenging and increasingly controversial practice. Skeletal remains may show evidence of trauma to the pelvis and skull, providing clues as to cause of death. Pelvic injuries are associated with high rates of mortality from hemorrhage and disruption of the genitourinary system, and evidence of genital mutilation may be present. Forensic methods suggest the Life skull is consistent with male sex. Ancestry, age at death and age of the remains are unable to be determined from the photo. Publication of the Life skull led to public disapproval and an Army memorandum condemning the practice of taking enemy remains. Conclusions: The pelvis and the skull provide useful, objective evidence when studying victims of past wars. Accurate determination of age at death, sex, and likely ancestry may be established from skeletal remains. Forensic methods and paleopathology can help restore the humanity lost by the faceless victims of war.

Comparison Study between Fetal Kidney Length and Transcerebellar Diameter to Determine Gestational age in the Third Trimester

Introduction and Aim: An accurate determination of gestational age (GA) is crucial to the management of all pregnancies, particularly high-risk pregnancies. This study aimed to comparing between the accuracy of ultrasonographic fetal kidney length and Transcerebellar diameter in GA determination in third trimester.&#x0D; Patients and methods: The study was a cross sectional one, carried out at the department of Obstetrics and Gynecology, Damietta Faculty of Medicine, Al-Azhar University, Damietta, Egypt. The study had been performed between January 2021 and January 2022. All were submitted to a detailed history, routine antenatal investigations, general and obstetrical examination. Then, measurements of all fetal biometric parameters were recorded using a real- time, grayscale, 3.5–5.0 MHz curvilinear array transducer. Results were compared to the gestational age determined by last menstrual period.&#x0D; Results: The patient age ranged between 18 and 37 years, their weight ranged between 55 and 109 kg, while gravidity ranged between 1 and 5 and parity ranged between 0 and 4. The GA as determined by last menstrual period (LMP) was ranged between 28 and 40 weeks. The calculated GA by different measurements were also included and they were around the same measurements as determined by LMP. This was confirmed by the absent statistically significant difference between GA by LMP and any of calculated gestational age by any method. The mean fetal kidney length is more accurate in determination of gestational age than transcerebellar diameter (96.3% vs 89.8%) and both were significantly correlated with other calculated gestational ages.&#x0D; Conclusion: The length of the fetal kidney length proportionately correlated with fetal gestation age with powerful correlation coefficient. Fetal kidney length is found to be more accurate in GA determination than transcerebellar diameter (TCD).

Beta dose heterogeneity in sediment samples measured using a Timepix pixelated detector and its implications for optical dating of individual mineral grains

Single-grain optical dating has been widely used to estimate depositional ages for Quaternary sediments. An understanding of the sources influencing the dispersion of equivalent dose (D e ) estimates from individual grain measurements is essential for accurate age determination. Beta microdosimetry (i.e., beta dose deposition at the sub-millimetre scale) is a known cause of spread in single-grain D e values, so the detection and assessment of beta dose rate ( D ˙ β ) variation is important to properly interpret these data. Here we demonstrate the application of Timepix, a pixelated detector that directly measures in situ beta emissions based on cluster analysis, to determine the beta microdosimetry of natural sediment samples from a cave deposit in Russia and a sand dune in Australia. We describe a Timepix measurement and data processing procedure for natural sediments, and establish sample-specific calibration curves using associated sample radioelement concentrations to convert Timepix count rates into estimates of D ˙ β . On the basis of the Timepix analysis, a 2D ‘heat map’ of D ˙ β at sub-millimetre resolution was obtained for each sample. Our results show that the D ˙ β estimates are heterogeneous and their non-uniformity gives rise to 9 ± 4 to 26 ± 5% overdispersion in the single-grain D e distributions for the samples examined here. We discuss the likely sources of D ˙ β heterogeneity, based on micromorphological investigations of these sediment samples, which include a variety of materials present in natural deposits associated with D ˙ β ‘hot’ and ‘cold’ spots. A comparison of the D ˙ β dispersion with that of the corresponding single-grain D e values shows that the scatter among the latter can be fully or partly explained by beta microdosimetry and other known sources of overdispersion. • Timepix pixelated detector used to measure beta dose rates of natural sediments. • Measurement and data analysis procedure proposed and tested on four samples. • Spatially-resolved ‘heat map’ of beta dose rates obtained at sub-millimetre resolution. • Beta heterogeneity gives rise to ∼9–26% overdispersion of single-grain D e values. • Beta heterogeneity can fully or partly explain overdispersion of single-grain D e values.

EVALUATION OF FETAL THIGH CIRCUMFERENCE AS AN ADDITIONAL MARKER FOR FOETAL BIOMETRY

Objective: Accurate determination of gestational age is the sine qua non of optimal management and hence prognostication of all pregnancies.A meticulous biometry ensures timely interventions resulting in favorable maternal and fetal outcomes. Traditionally, the parameters of Biparietal diameter (BPD), Femur length (FL), Head circumference (HC), and Abdominal circumference (AC) have been utilized for routine fetal biometry. The present study aims to assess the utility of Fetal Thigh Circumference (ThC) as an additional marker for fetal biometry. Methods: The present retrospective, observational, and cross-sectional study was done in the Departments of Radiodiagnosis and Obstetrics and Gynaecology in an ethically and socio-economically diverse group of pregnant females. All pregnant females with singleton pregnancies between 22 and 40 weeks of gestation and fulfilling the inclusion and exclusion criteria were subjected to ultrasound examination. Subsequently analysis was done for the data collected. Results: There were a total of 287 participants in present study group with mean age of 23±3.4 years. The strength of agreement almost perfect (&gt;0.99) between the mean observed ThC to ThC values by Deter et al. taken as standard. There was a highly significant positive correlation between gestational period and standard biometry parameters and ThC. ThC model for prediction will be better than standard biometry parameters of BPD, HC and AC but not as good as FL model according to the regression analysis of the present study. Conclusions: There is concordance of fetal ThC as an accurate predictor of period of gestation only after FL. It can be combined with standard biometry parameters to give a better estimation of period of gestation.

Allogeneic Hematopoietic Cell Transplantation Causes Accelerated Aging Both of the Hematopoietic and Somatic Systems

Recent reports suggest that survivors of hematopoietic cell transplantation (HCT) exhibit clinical features consistent with accelerated aging including increased incidence of endocrinological, pulmonary and cardiovascular morbidity, other severe chronic disorders and excess of secondary malignancies. In addition, high incidence of frailty - a physiologic measure of aging, was documented in childhood cancer survivors. Data from additional studies suggest that cytotoxic therapy triggers an acceleration of the aging process whose likely mechanism may be cellular senescence. In order to corroborate the physiological and epidemiological data, more accurate biological markers of senescence should be assessed. Indeed, several studies, including from our group, reported on telomere shortening after HCT. Other studies showed elevation of inflammatory biomarkers, those being associated with the aging process. The accuracy of these biological markers is disputable due to inherent problems in their interpretation. Recently, several more accurate biomarkers of cellular age have been reported. The most promising is the DNA methylation status of several genomic loci, which can determine the cellular age with accuracy of 1.5 to 3 years. Additional markers, such as p16ink4A and IL-6 concentrations in serum are also considered as reliable markers of age.The present study assessed the hematopoietic and non-hematopoietic systems aging trajectory after allogeneic HCT. We took advantage of being able to assess quantitatively the hematopoietic system comparing blood cells derived from one person (the donor) and residing in two different hosts (donor and recipient). The blood cells aging may be affected by replicative stress after HCT and therefore do not necessarily represent the whole body aging; therefore we measured the age of buccal epithelial cells of the transplant survivors as well. For cellular age determination we used DNA methylation in three sites, previously validated as an accurate age determination method, p16ink4A blood levels and serum IL-6 concentration. To the best of our knowledge, this is the first study employing these novel markers for assessment of accelerated aging in a clinical setting.26 survivors of allogeneic HCT (median age, 48 years; range, 28 to 71) were evaluated at a median of 3.6 (range, 2.2 to 9) years after HCT. The cellular age of donor blood cells residing in the recipient was compared with the age of the blood cells residing in the respective donor and the cellular age of the patients' buccal epithelial cells was compared with their chronological age.In 21 out of 26 patients the cellular age of donor blood cells residing in the patients was significantly higher than that of the respective cells residing in the donor as determined by DNA methylation. The mean excess aging of the cells was 8.3 (range -5 to 30) years and in most of the patients the cells were more than 10 years “older” than the donors' cells. The buccal epithelial cells predicted age was also significantly higher than the chronological age; the median excess of aging was 8.7 (range, -37 to 10.5) years. The two other biomarkers of aging: IL-6 and p16ink4A also demonstrated advanced age compared to the chronological age. There was no association between the magnitude of aging and previous chemotherapy or GVHD. Telomere length was not significantly shortened in the transplanted patients compared to their donors, consistent with previous reports demonstrating initial telomere shortening and eventual return to normal levels.In conclusion, allogeneic stem cell transplantation is associated with significant accelerated aging of both of the hematopoietic and somatic systems. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Ar-Ar chronology of the brittle deformation age for the ore-controlling shear zones in the Jiaodong Peninsula and it's constrains on gold mineralization

胶东地区是典型的剪切带型金矿集中区，精确厘定该地区控矿剪切带的活动时代，可为探讨剪切带与金矿成因关系提供关键的时限约束，并且对矿床成矿模式的建立具有至关重要的意义。大量矿床地质证据显示胶东地区控矿剪切带中脆性变形活动对金矿体的形成具有直接影响，但其脆性变形时代尚不十分清楚。据此，本文在详细研究金矿体赋存特征的基础上，系统选取胶东焦家、玲珑、邓格庄、乳山这四个金矿区控矿剪切带断层泥中白云母进行⁴⁰Ar-³⁹Ar年代学研究。定年结果显示，胶东地区焦家剪切带、招平剪切带以及牟乳剪切带的脆性变形时代分别为110.3±1.5Ma、122.8±1.7Ma、119.6±1.2Ma~115.8±1.4Ma。其中焦家剪切带的脆性变形时代明显晚于招平和牟乳剪切带，可能代表了焦家蚀变岩型矿化形成后易遭受后期的构造叠加。综合胶东各金矿区控矿剪切带变形时代、岩体侵位时代、成矿时代及剪切带活动特征和矿体产出特征，本文认为在多期岩体侵位以及控矿剪切带递进变形过程中，剪切带韧性变形区中由高压流体作用产生的同期脆性破裂可形成脉型矿化，如乳山金矿；而在脆-韧性和脆性变形区中发生的大规模脆性变形可导致脉型和蚀变岩型矿化的形成，如玲珑、邓格庄和焦家金矿。但随着剪切带的递进变形和隆升剥蚀，后期多期次的脆性构造变形叠加，可导致多种矿化类型出现在同一构造部位，如焦家金矿中石英脉型和蚀变岩型矿化。;Jiaodong Peninsula is a typical concentration area for shear zone type gold deposits. Accurate determination of the deformation age of ore-controlling shear zones in this area can provide a key time limit for exploring the relationship between shear zones and the genesis of gold deposits, and is of vital significance to the establishment of metallogenic mechanism. A large number of geological evidences show that the formation of gold orebodies is directly controlled by brittle deformation activities of ore-controlling shear zones in Jiaodong Peninsula, but this deformation age is still unclear. Based on detailed study of the occurrence characteristics of orebodies, we systematically selected muscovite samples from fault gouge in Jiaojia, Linglong, Denggezhuang and Rushan gold mining areas for the Ar-Ar chronology study. ⁴⁰Ar/³⁹Ar dating results show that the brittle deformation ages of Jiaojia, Zhaoping and Muru shear zones in Jiaodong Peninsula are 110.3±1.5Ma, 122.8±1.7Ma and 119.6±1.2Ma~115.8±1.4Ma, respectively. Among them, the brittle deformation age of Jiaojia shear zone is obviously later than those of Zhaopin and Muru shear zones, which may represent that the altered rock type mineralization in Jiaojia deposit is susceptible to structural superposition in the later period. Comprehensively comparing shear zone deformation ages, pluton emplacement ages, metallogenic ages, shear zone activities and orebody occurrence characteristics in Jiaodong gold deposits, it is suggested that: (1) The contemporaneous brittle fractures caused by high-pressure fluids in ductile deformation region of shear zones can lead to the formation of vein type mineralization, e.g. Rushan gold deposits; (2) Large-scale brittle deformation in brittle-ductile and brittle region can lead to the formation of vein type and altered rock type mineralization, e.g. Linglong, Denggezhuang and Jiaojia gold deposits. Both stages take place during the process of multi-stage emplacement and progressive deformation of ore-controlling shear zones. However, with the progressive deformation and uplift denudation of shear zones, the superposition of brittle deformation in the late stage may lead to the occurrence of multiple mineralization types in the same structural site, e.g. quartz vein type and altered rock type mineralization in Jiaojia gold deposit.

Prevalence and diagnostic accuracy of microcephaly in a pediatric cohort in Brazil: a retrospective cross-sectional study

ObjectiveWe sought to describe the prevalence of microcephaly and to compare the different cutoff points established by the Brazilian Ministry of Health at various times during a Zika virus epidemic. As a secondary aim, we investigated the possible etiology of the microcephaly. MethodThis retrospective study utilized newborn participants in the Zika Cohort Study Jundiaí. Newborns from the Zika Cohort Study Jundiaí with an accurate gestational age determination and complete anthropometric data were analyzed, and microcephaly was diagnosed according to the INTERGROWTH-21st curve. At delivery, fluids were tested for specific antibodies and for viruses. Brain images were evaluated for microcephaly. Receiver Operating Characteristic curves were plotted to define the accuracy of different cutoff points for microcephaly diagnosis. ResultsOf 462 eligible newborns, 19 (4.1%) were positive for microcephaly. Cutoff points corresponding to the curves of the World Health Organization yielded the best sensitivity and specificity. Three of the microcephaly cases (15.8%) were positive for Zika virus infections; nine (47.4%) had intrauterine growth restriction; one had intrauterine growth restriction and was exposed to Zika virus; three had a genetic syndrome (15.8%); and three had causes that had not been determined (15.8%). ConclusionsMicrocephaly prevalence was 4.1% in this study. Cutoff values determined by the World Health Organization had the highest sensitivity and specificity in relation to the standard IG curve. The main reason for microcephaly was intrauterine growth restriction. All possible causes of microcephaly must be investigated to allow the best development of an affected baby.

Research Progress of Adult Age Determination with Imaging Methods

Adult age determination plays an important role in individual identification, criminal investigation and social welfare. The most popular adult age determination indicators are pubic symphysis, iliac auricular surface, costal cartilage, cranial sutures, teeth, laryngeal cartilage, etc. In recent years, with the progress of CT imaging and 3D reconstruction technology, the adult age determination study gradually has transferred from a time-consuming general observation of bones with complex pre-processing in the past to the non-destructive, convenient, time-saving and easy to store image analysis technology. To explore more accurate, rapid and convenient adult age determination methods, multiple imaging methods and artificial intelligence have been applied in adult age determination. This paper reviews the common methods and research progress of adult age determination at home and abroad, infers the development direction of adult age determination, in order to provide reference for the improvement and optimization of forensic adult age determination.

FeSTwo, a two-step feature selection algorithm based on feature engineering and sampling for the chronological age regression problem

Accurate determination of the sample's chronological age is an important forensic problem. This regression problem may be improved by selecting appropriate methylomic features. Most of the existing feature selection algorithms, however, optimize the regression performance by considering only the original features. This study proposed four feature engineering strategies to transform the original methylomic features. The regression performance of the age regression model was improved by the resampling-based feature selection algorithm FeSTwo proposed in this study. FeSTwo outperformed the parallel algorithms used in the previous studies even with the electronic health record data. The age prediction performance of the FeSTwo-detected features was also confirmed for another independent dataset. The study results demonstrated that the proposed model, FeSTwo, led to a more than 8% reduction in root-mean-square error (RMSE) on the test dataset with only 70 features.

Ambiguities in using telomere length for age determination in two North American bat species

AbstractThe age of an animal, determined by time (chronological age) as well as genetic and environmental factors (biological age), influences the likelihood of mortality and reproduction and thus the animal’s contribution to population growth. For many long-lived species, such as bats, a lack of external and morphological indicators has made determining age a challenge, leading researchers to examine genetic markers of age for application to demographic studies. One widely studied biomarker of age is telomere length, which has been related both to chronological and biological age across taxa, but only recently has begun to be studied in bats. We assessed telomere length from the DNA of known-age and minimum known-age individuals of two bat species using a quantitative PCR assay. We determined that telomere length was quadratically related to chronological age in big brown bats (Eptesicus fuscus), although it had little predictive power for accurate age determination of unknown-age individuals. The relationship was different in little brown bats (Myotis lucifugus), where telomere length instead was correlated with biological age, apparently due to infection and wing damage associated with white-nose syndrome. Furthermore, we showed that wing biopsies currently are a better tissue source for studying telomere length in bats than guano and buccal swabs; the results from the latter group were more variable and potentially influenced by storage time. Refinement of collection and assessment methods for different non-lethally collected tissues will be important for longitudinal sampling to better understand telomere dynamics in these long-lived species. Although further work is needed to develop a biomarker capable of determining chronological age in bats, our results suggest that biological age, as reflected in telomere length, may be influenced by extrinsic stressors such as disease.

Cathodoluminescence and Laser-Induced Fluorescence of Calcium Carbonate: A Review of Screening Methods for Radiocarbon Dating of Ancient Lime Mortars

ABSTRACTAccurate radiocarbon (14C) dating of lime mortars requires a thorough mineralogical characterization of binders in order to verify the presence of carbon-bearing contaminants. In the last 20 years, cathodoluminescence (CL) has been widely used for the identification of geologic calcium carbonate (CaCO3) aggregates and unreacted lime lumps within the particle size fraction selected for carbon recovery. These components are major sources of older and younger carbon, respectively, and should be removed to obtain accurate age determinations. More recently, laser-induced fluorescence (LIF) has provided another means of investigating the preservation state and composition of CaCO3 binders. Considered the growing interest of the mortar dating community in the latest advancements of these analytical methods, here we review the principles of CL and LIF of CaCO3, their instrument setup, and their application to the characterization of ancient lime mortars used for 14C dating. In addition, we provide examples of SEM-CL and LIF analyses using high-resolution instrumentation, we discuss current issues and propose future lines of research.

Yearling proportion correlates with habitat structure in a boreal forest landbird community.

Landbird vital rates, such as productivity and adult survivorship, can be estimated by modeling mist-netting capture data. The proportion in which an adult breeding bird is 1 year of age (a “yearling”), however, has been studied only minimally in a few landbird species. Here we relate yearling proportion to habitat-structure covariates, including reclamation age, in a boreal forest landbird community. Data were collected at 35 constant-effort mist-netting stations over a 6-year period, and consisted of 12,714 captures of adults, of 29 landbird species, including 4,943 captures of yearlings. Accuracy of age determination (yearling or older) was assessed based on recapture data and error rates were estimated at a mean of 8.1% (range 0.0–19.4%) among the 29 species, with 20 species showing age-error rates <10%. The estimated mean yearling proportion was 0.407, ranging from 0.178 to 0.613 among species. Remote-sensed Enhanced Vegetation Index (EVI), a measure of habitat greenness, was positively correlated with age since reclamation up to 20 years, at which time it became comparable to that of natural stations. The probability of capturing a yearling for species associated with mature forest was lower at stations with higher EVI and the opposite was the case for species favoring successional habitats. These results suggest that yearling birds are being excluded from preferred breeding habitats by older birds through despotism and/or that yearlings are simply selecting poorer habitat due to lack of breeding experience or other factors. This dynamic appears to be operating in multiple species within this forest landbird community. Captured yearlings may also be “floaters”, or non-breeding individuals not holding territories. However, presuming that yearlings show lower reproductive success whether floating or not, our results suggest that stations with high yearling proportions could be located within sink as opposed to source habitats. Overall, we infer that yearling proportion may become an important vital-rate measure of habitat quality and reclamation efforts, when combined with indices of population size, productivity, reproductive condition and survivorship.

A comparison of automated approaches to extracting englacial-layer geometry from radar data across ice sheets

AbstractRadar surveys across ice sheets typically measure numerous englacial layers that can often be regarded as isochrones. Such layers are valuable for extrapolating age–depth relationships away from ice-core locations, reconstructing palaeoaccumulation variability, and investigating past ice-sheet dynamics. However, the use of englacial layers in Antarctica has been hampered by underdeveloped techniques for characterising layer continuity and geometry over large distances, with techniques developed independently and little opportunity for inter-comparison of results. In this paper, we present a methodology to assess the performance of automated layer-tracking and layer-dip-estimation algorithms through their ability to propagate a correct age–depth model. We use this to assess isochrone-tracking techniques applied to two test case datasets, selected from CreSIS MCoRDS data over Antarctica from a range of environments including low-dip, continuous layers and layers with terminations. We find that dip-estimation techniques are generally successful in tracking englacial dip but break down in the upper and lower regions of the ice sheet. The results of testing two previously published layer-tracking algorithms show that further development is required to attain a good constraint of age–depth relationships away from dated ice cores. We recommend that auto-tracking techniques focus on improved linking of picked stratigraphy across signal disruptions to enable accurate determination of the Antarctic-wide age–depth structure.

Geochronology of Uraninite Revisited

Identification of uraninite provenance for the purpose of nuclear forensics requires a multifaceted approach. Various geochemical signatures, such as chondrite normalized rare earth element patterns, help identify and limit the potential sources of uraninite based on the geological setting of the uranium ore mineralization. The inclusion of accurate age determinations to discriminate geochemical signatures for natural uranium ores may help to potentially restrict geographical areas for provenance consideration. Determining a robust age for uraninite formation is somewhat difficult, due to well known, inherent difficulties associated with open system behavior that involve either uranium and/or lead loss or gain. However, open system behavior should not perturb their Pb isotopic compositions to the same degree as Pb isotopes should not fractionate during alteration processes. Here, a suite of pristine and altered samples of uraninite was examined for their Pb isotope compositions, and these yielded geologically meaningful secondary Pb–Pb isochron ages. The degree of alteration within individual uraninite samples, which is extremely variable, does not appear to affect the calculated ages. The approach adopted here yields insightful age information, and hence, is of great value for source attribution in forensic analyses of raw nuclear materials.

Inferring the parallax of Westerlund 1 from Gaia DR2

ABSTRACT Westerlund 1 (Wd1) is potentially the largest star cluster in the Galaxy. That designation critically depends upon the distance to the cluster, yet the cluster is highly obscured, making luminosity-based distance estimates difficult. Using Gaia Data Release 2 (DR2) parallaxes and Bayesian inference, we infer a parallax of $0.35^{+0.07}_{-0.06}$ mas corresponding to a distance of $2.6^{+0.6}_{-0.4}$ kpc. To leverage the combined statistics of all stars in the direction of Wd1, we derive the Bayesian model for a cluster of stars hidden among Galactic field stars; this model includes the parallax zero-point. Previous estimates for the distance to Wd1 ranged from 1.0 to 5.5 kpc, although values around 5 kpc have usually been adopted. The Gaia DR2 parallaxes reduce the uncertainty from a factor of 3 to 18 per cent and rules out the most often quoted value of 5 kpc with 99 per cent confidence. This new distance allows for more accurate mass and age determinations for the stars in Wd1. For example, the previously inferred initial mass at the main-sequence turn-off was around 40 M⊙; the new Gaia DR2 distance shifts this down to about 22 M⊙. This has important implications for our understanding of the late stages of stellar evolution, including the initial mass of the magnetar and the LBV in Wd1. Similarly, the new distance suggests that the total cluster mass is about four times lower than previously calculated.

Differential Gene Expression for Age Estimation of Forensically Important Sarcophaga peregrina (Diptera: Sarcophagidae) Intrapuparial.

Sarcophaga peregrina is an important flesh fly species for estimating the minimum postmortem interval (PMImin) in forensic entomology. The accurate determination of the developmental age is a crucial task for using necrophagous sarcophagids to estimate PMImin. During larval development, the age determination is straight forward by the morphological changes and variation of length, weight, and width; however, the age estimation of sarcophagid intrapuparial is more difficult due to anatomical and morphological changes not being visible. The analysis of differentially expressed genes (DEGs) during sarcophagid metamorphosis is a potential method for age estimation of intrapuparial. In the present study, real-time quantitative polymerase chain reaction (RT-qPCR) was used to analyze the differential gene expression level of S. peregrina intrapuparial in different constant temperatures (35°C, 25°C, and 15°C). In addition, the appropriate reference genes of S. peregrina were selected in the intrapuparial and at different temperatures to obtain reliable and valid gene expression profiles. The results indicated that two candidate genes (18S rRNA and 28S rRNA) were the most reliable reference genes, and four DEGs (Hsp90, A-alpha, AFP, AFBP) have the potential to be used to more accuracy estimate the age of S. peregrina intrapuparial.

Sonographic estimation of gestational age from 20 to 40 weeks by fetal kidney lengths\u2019 measurements among pregnant women in Portharcourt, Nigeria

BackgroundUltrasonography has become an indispensible tool in the management of obstetric patients. Accurate determination of fetal gestational age (FGA) has posed great challenge to patient management as the accuracy of traditional biometric parameters decreases with advance in gestation age. Accuracy of fetal kidney length (FKL) in the determination of FGA at third trimester has been documented in other population. This study is aimed to create baseline reference values of fetal kidney lengths in a Nigerian population as previous studies show population specific variations.MethodsThis prospective cross sectional study was carried out on 534 pregnant women between 20 and 40 weeks of gestation who met the inclusion criteria at Diamond Biomedical Services Ltd. A pilot study was conducted on 20 patients to determine the reproducibility and reliability of ultrasound measurement of FKL. Fetal kidney lengths were calculated as mean of three separate measurements. The 5th, 50th and 95th percentiles were calculated using least squared regression analysis. Third polynomial regression models were used to establish the relationship between right and left FKL and FGA.ResultsBoth FKL measurements are highly reproducible with excellent correlation and agreement within and between sonographers. It correlates strongly with gestational age while the relationships between right and left kidney lengths with gestational age were established using the following regression equations: RKL = − 11.18 + 1.193 × FGA − 0.0350 × FGA2 + 0.00037 × FGA3 and LKL = − 12.57 + 1.332 × FGA − 0.0390 × FGA2 + 0.00040 × FGA3 for right and left kidneys respectively.ConclusionNigerian population specific baseline reference values of FKLs for the estimation of FGA should be adopted rather than relying on the Caucasians values as universal patterns.

Abstract 828: Accelerated epigenetic aging in bladder cancer patients

Abstract Aging represents the most important risk factor for many chronic diseases including cardiovascular diseases, diabetes, and cancer, therefore understanding the mechanisms of aging is a fundamental step for designing new treatments for chronic diseases. DNA methylation is the most reliable and accurate molecular marker for aging quantification, however, genome-wide DNA methylation profiling techniques, such as reduced representative bisulfite sequencing and Illumina Bead Array that are widely used in aging research are prohibitively expensive and have poor data quality at low-read coverage sites. Here we report a robust targeted bisulfite sequencing approach, called SWARM® (Simplified Whole-panel Amplification Reaction Method), for the accurate biological age determination. SWARM™ is flexible and low cost, requires relatively low DNA starting material, allows the simultaneous amplification and sequencing of hundreds of loci, and has shown to increase sample throughput. Using the SWARM® approach, we were able to analyze the methylation level of several hundreds of age-associated loci including the published Horvath Clock sites. Gender-specific age-predictive models were built using the elastic net regression of DNA methylation levels of the loci and chronological age of urine DNA samples of over 300 healthy subjects of 18 to 88 years old. Urine samples from bladder cancer patients exhibit significant age acceleration, with an average of &amp;gt;10 years. In brief, our gender-specific urine DNAge® analysis is a tool for the precise biological aging quantification and can be used to address questions in aging and urinary track cancers. Citation Format: Yap Ching Chew, Wei Guo, Xiaojing Yang, Paolo Piatti, Mingda Jin, Keith Booher, Benjamin Jara, Xi-Yu Jia. Accelerated epigenetic aging in bladder cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 828.