Accurate Age Determination Research Articles

The chemical evolution of the Milky Way thin disk using solar twins

In this study we address whether the age--metallicity relation (AMR) deviates from the expected trend of metallicity increasing smoothly with age. We also show the presence (or absence) of two populations, as recently claimed using a relatively small dataset. Moreover, we studied the Milky Way thin disk's chemical evolution using solar twins, including the effect of radial migration and accretion events. In particular, we exploited high-resolution spectroscopy of a large sample of solar twins in tandem with an accurate age determination to investigate the Milky Way thin disk age--metallicity relationship. Additionally, we derived the stars' birth radius and studied the chemical evolution of the thin disk. We discovered that statistical and selection biases can lead to a misinterpretation of the observational data. An accurate accounting of all the uncertainties led us to detect no separation in the AMR into different populations for solar twins around the Sun ($-0.3 < Fe/H < 0.3$ dex). This lead us to the conclusion that the thin disk was formed relatively smoothly. For the main scenario of the Milky Way thin disk formation, we suggest that the main mechanism for reaching today's chemical composition around the Sun is radial migration with the possible contribution of well-known accretion events such as Gaia -Enceladus/Sausage (GES) and Sagittarius (Sgr).

A methodological approach to age estimation of the intra-puparial period of the forensically relevant blow fly Calliphora vicina via Fourier transform infrared spectroscopy.

Estimating the age of immature blow flies is of great importance for forensic entomology. However, no gold-standard technique for an accurate determination of the intra-puparial age has yet been established. Fourier transform infrared (FTIR) spectroscopy is a method to (bio-)chemically characterise material based on the absorbance of electromagnetic energy by functional groups of molecules. In recent years, it also has become a powerful tool in forensic and life sciences, as it is a fast and cost-effective way to characterise all kinds of material and biological traces. This study is the first to collect developmental reference data on the changes in absorption spectra during the intra-puparial period of the forensically important blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Calliphora vicina was reared at constant 20°C and 25°C and specimens were killed every other day throughout their intra-puparial development. In order to investigate which part yields the highest detectable differences in absorption spectra throughout the intra-puparial development, each specimen was divided into two different subsamples: the pupal body and the former cuticle of the third instar, that is, the puparium. Absorption spectra were collected with a FTIR spectrometer coupled to an attenuated total reflection (ATR) unit. Classification accuracies of different wavenumber regions with two machine learning models, i.e., random forests (RF) and support vector machines (SVMs), were tested. The best age predictions for both temperature settings and machine learning models were obtained by using the full spectral range from 3700 to 600 cm-1. While SVMs resulted in better accuracies for C. vicina reared at 20°C, RFs performed almost as good as SVMs for data obtained from 25°C. In terms of sample type, the pupal body gave smoother spectra and usually better classification accuracies than the puparia. This study shows that FTIR spectroscopy is a promising technique in forensic entomology to support the estimation of the minimum post-mortem interval (PMImin), by estimating the age of a given insect specimen.

The Effect of Starspots on Spectroscopic Age and Mass Estimates of Nonaccreting T Tauri Stars in the Taurus–Auriga Star-forming Region

Accurate age and mass determinations for young pre-main-sequence stars are made challenging by the presence of large-scale starspots. We present results from a near-infrared spectroscopic survey of 10 T-Tauri Stars in Taurus-Auriga that characterize spot-filling factors and temperatures, the resulting effects on temperature and luminosity determinations, and the consequences for inferred stellar masses and ages. We constructed composite models of spotted stars by combining BTSettl-CIFIST synthetic spectra of atmospheres to represent the spots and the photosphere along with continuum emission from a warm inner disk. Using a Markov Chain Monte Carlo algorithm, we find the best-fit spot and photospheric temperatures, spot-filling factors, as well as disk-filling factors. This methodology allowed us to reproduce the 0.75–2.40 μm stellar spectra and molecular feature strengths for all of our targets, disentangling the complicated multicomponent emission. For a subset of stars with multiepoch observations spanning an entire stellar rotation, we correlate the spectral variability and changes in the filling factors with rotational periods observed in K2 and AAVSO photometry. Combining spot-corrected effective temperatures and Gaia distances, we calculate luminosities and use the Stellar Parameters of Tracks with Starspots models to infer spot-corrected masses and ages for our sample of stars. Our method of accounting for spots results in an average increase of 60% in mass and a doubling in age with respect to traditional methods using optical spectra that do not account for the effect of spots.

Eruption Pattern of Permanentcanine and Premolar Teeth among School Children aged 10 to 12 Years in a Rural Area: A Cross-Sectional Study

Background: Forensic dentistry is a specialized field that evaluates dental evidence to identify unidentified individuals and missing persons in legal proceedings. Dental charts are compared with known records to establish identity. Accurate age determination is crucial, and dental age assessment is reliable up to 17 years. The study aims to analyze permanent teeth eruption patterns of canines and premolars in school children aged 10 to 12, contributing valuable insights for accurate age determination and identification in legal cases. The research seeks to aid the interest of justice in criminal, civil, and employment-related scenarios by understanding dental eruption patterns in this age group.Methods: This was across-sectional study conducted among the school children of south Kerala belonging to age group of 10-12 years. Eruption pattern of permanent canines and premolars of 562 subjects were recorded and analyzed using SPSS software.Conclusion: Sequence of eruption pattern of permanent canines and premolars were compared and it was observed with statistical significance that eruption of canineprecedes the eruption of second premolars. All the teeth erupted earlier in females compared to males.There was a significant relation with reduced body mass index and delayed eruption of teeth.

Statoliths of Rapana venosa (Valenciennes, 1846): Microstructure, application for age determination and growth modelling

Rapana venosa (Valenciennes, 1846) is an invasive species that has spread widely around the world, which has commercial importance. For scientifically sound fishery management, accurate age determination is necessary, while the methods currently used have disadvantages. To fulfill the need for a more accurate technique, the microstructure of R. venosa statoliths collected in the northern part of the Black Sea (near the Bolshoy Utrish cape) was studied. Statoliths have well-marked concentric increments, which allows counting with sufficient accuracy. The annual periodicity of R. venosa statolith increments was cross validated using spawning marks on the shells. The growth of veined whelks was the best described by Von Bertalanffy function, with the following coefficients: L∞ = 96.19; k = 0.125; t0 = 0.043. The model accounted for 83% of variance. Moreover, the possibility to reconstruct the age of molluscs based on statolith diameter was tested. It was revealed that the number of increments versus statolith diameter relationship is exponential, the developed model described 99% of variance. Based on these data the growth of R. venosa was modelled again, resulting model accounted for 88% of variance. Coefficients of the model were: L∞ = 106.42; k = 0.102; t0 = 0.136. Potential benefits and limitations of the applied methods are discussed.

Age Estimation in Brazilian Adults Using the Pulp/Tooth Ratio of the Maxillary Canine and Mandibular Second Premolar.

(1) Background/Objectives: Accurate determination of chronological age is crucial in legal dental identification. This study aimed to compare the effectiveness of different formulas in estimating the age of a Brazilian subpopulation by analyzing the pulp/tooth ratio of the maxillary canine and mandibular second premolar in panoramic and periapical radiographs. (2) Methods: The sample consisted of panoramic and periapical radiographs of 247 individuals. The file of each radiograph was opened in the Adobe Photoshop CS4® program to outline and obtain values in pixels for calculating the pulp/tooth ratio. Statistical analysis was conducted using the SPSS program, with a significance level set at 5%. (3) Results: The interclass correlation coefficient demonstrated excellent intra-observer agreement (0.990-0.999). The determination coefficients (R2) suggested that only 30-35% of the actual age results could be explained by the pulp/tooth ratio. The smallest differences were observed with Cameriere's formula for the mandibular second premolar on panoramic radiographs (+4.1 years). The greatest differences were found with the formulas for the mandibular second premolar in panoramic radiographs of the Korean (+12.5 years) and Portuguese (-12.1 years) populations. (4) Conclusions: The equations employed showed little agreement between the actual age and the estimated age.

Incidence of pneumococcal disease in children ≤48 months old in the United States: 1998–2019

BackgroundPneumococcal disease (PD) is a major cause of morbidity and mortality among children, particularly in the youngest age groups. This study aimed to assess the incidence of PD over time by age group in young children with commercial or Medicaid coverage in the US. MethodsEpisodes of invasive pneumococcal disease (IPD), all-cause pneumonia (ACP), and acute otitis media (AOM) were identified in the MarketScan® Commercial and Medicaid claims databases using diagnosis codes among children aged ≤ 48 months with confirmed date of birth (DoB), at any time during the study period (1998–2019). DoB was assigned using diagnosis codes for birth or delivery using the child’s or mother’s medical claims to ensure accurate age determination. Annual incidence rates (IRs) were calculated as number of disease episodes/100,000 person-years (PY) for IPD and ACP and episodes/1,000 PY for AOM, for children aged 0–6, 7–12, 12–24, and 25–48 months. ResultsAnnual IPD IRs declined from 53 to 7 episodes/100,000 PY between 1998 and 2019 in commercially-insured and 58 to 9 episodes/100,000 PY between 2001 and 2019 in Medicaid-insured children. Annual ACP IRs declined from 5,600 to 3,952 episodes/100,000 PY, and from 6,706 to 4,521 episodes/100,000 PY, respectively, over these periods. In both populations, children aged 0–6 months had the highest incidence of IPD and inpatient ACP. Annual AOM IRs declined from 1,177 to 738 episodes/1,000 PY (commercially-insured) and 633 to 624 episodes/1,000 PY (Medicaid-insured), over these periods. IRs were higher in rural vs. urban areas for all disease manifestations. ConclusionsIncidence rates of IPD, ACP, and AOM decreased in children with commercial insurance and Medicaid coverage from 1998 to 2019. However, burden of disease remained substantial, with higher annual IRs for IPD and ACP for Medicaid-insured vs. commercially-insured children. IPD and inpatient ACP were most common in the youngest children 0–6 months old, followed by the 7–12-month age group.

Estimation of Human Chronological Age from Buccal Swab Samples through a DNA Methylation Analysis Approach of a Five-Locus Multiple Regression Model.

Recent advancements in forensic genetics have facilitated the extraction of additional characteristics from unidentified samples. This study delves into the predictive potential of a five-gene (ELOVL2, FHL2, KLF14, C1orf132, and TRIM59) methylation rate analysis for human age estimation using buccal swabs collected from 60 Italian volunteers. The methylation levels of specific CpG sites in the five genes were analyzed through bisulfite conversion, single-base extension, and capillary electrophoresis. A multivariate linear regression model was crafted on the training set, then the test set was employed to validate the predictive model. The multivariate predictive model revealed a mean absolute deviation of 3.49 years in the test set of our sample. While limitations include a modest sample size, the study provides valuable insights into the potential of buccal swab-based age prediction, aiding in criminal investigations where accurate age determination is crucial. Our results also highlight that it is necessary to investigate the effectiveness of predictive models specific to biological tissues and individual populations, since models already proven effective for other populations or different tissues did not show the same effectiveness in our study.

Less is less: Photometry alone cannot predict the observed spectral indices of z ~ 1 galaxies from the LEGA-C spectroscopic survey

Aims. We test whether we can predict optical spectra from deep-field photometry of distant galaxies. Our goal is to perform a comparison in data space, highlighting the differences between predicted and observed spectra. Methods. The Large Early Galaxy Astrophysics Census (LEGA-C) provides high-quality optical spectra of thousands of galaxies at redshift 0.6 < z < 1. Broadband photometry of the same galaxies, drawn from the recent COSMOS2020 catalog, is used to predict the optical spectra with the spectral energy distribution (SED) fitting code Prospector and the MILES stellar library. The observed and predicted spectra are compared in terms of two age and metallicity-sensitive absorption features (HδA and Fe4383). Results. The global bimodality of star-forming and quiescent galaxies in photometric space is recovered with the model spectra. However, the presence of a systematic offset in the Fe4383 line strength and the weak correlation between the observed and modeled line strength imply that accurate age or metallicity determinations cannot be inferred from photometry alone. Conclusions. For now we caution that photometry-based estimates of stellar population properties are determined mostly by the modeling approach and not the physical properties of galaxies, even when using the highest-quality photometric datasets and state-of-the-art fitting techniques. When exploring a new physical parameter space (i.e. redshift or galaxy mass) high-quality spectroscopy is always needed to inform the analysis of photometry.

Zircon (U-Th)/He impact crater thermochronometry and the effects of shock microstructures on He diffusion kinetics

Accurate age determination of impact cratering events remains difficult and controversial. Less than a quarter of all documented impact craters are regarded as accurately and precisely age dated. Zircon (U-Th)/He (ZHe) dating of impactites has received recent attention as a novel technique to date impact structures. Complicated and localized post-impact hydrothermal systems could also affect the reliability of ZHe impact ages. We quantitatively define the effects of shock-induced microstructures on He diffusion kinetics in zircon with different shock microstructures characterized by Secondary Electron Microscopy (SEM) and electron backscatter diffraction (EBSD). We investigated samples from the Chicxulub and Ries impact craters, to compare diffusion kinetics from structures of different sizes, ages, and hydrothermal activity. Step-heating fractional-release experiments were used to quantify He diffusion kinetics of variably shocked zircon and examine the relationship of the experimentally derived diffusion domain sizes to the EBSD-defined subgrains. The diffusion data show a consistent activation energy independent of shock level, while shock microstructures, such as planar deformation bands (PDBs) and granular textures systemically and dramatically lower the He retentivity due to the microstructural reduction of the effective diffusion domain size. Shocked zircon were dated by ZHe and the less deformed grains yield ages within error of the accepted impact ages as determined by other methods (40Ar/39Ar and U-Pb), whereas the grains with PDBs or granular textures commonly exhibited younger ages. Thus, the characterization of impact-induced zircon microstructures is critical for determining accurate impact ages because shocked grains are less suitable for reliable impact dating, but potentially powerful for exploring temperature–time history of hydrothermal activity.

The genesis of calcite and dolomite carbonatite-forming magma by liquid immiscibility: a critical appraisal

AbstractLiquid immiscibility has become the preferred mode of genesis for the carbonatite rocks, which commonly, but not exclusively, accompany silicate rocks in alkaline-rock complexes. This concept has been universally based on the presumption that nephelinitic and phonolitic magmas can evolve to a stage where two conjugate immiscible liquids separate. It is assumed that these two liquids separate quickly, or even instantaneously, into discrete bodies of magma capable of being intruded or extruded with subsequent independent crystallization. Supporting evidence generally given is: alleged consanguinity as discrete occurrence of the two rock types; similarity of radiogenic isotope ratios; trace element contents similar to those predicted from experimentally derived partition coefficients. We do not accept that a general case for liquid immiscibility has been demonstrated; although we do accept that silicate and carbonate liquids are inherently immiscible, we maintain that they are not conjugate in a petrogenetic context. We have reviewed and critically examined the experimental data purporting to establish liquid immiscibility and find that when applied to natural rocks, they are based on inappropriate experimental designs, which are not relevant to the genesis of calcite or dolomite carbonatites, although they might have some relevance to Oldoinyo Lengai nyerereite–gregoryite lavas. The design of these experiments guarantees immiscibility and ensures that the carbonate liquids formed will be calcitic or sodium-rich. We dispute the validity of comparing the trace element contents of natural rocks, which in many instances do not represent liquid compositions, to experimentally determine partition coefficients. We consider that experimental design inadequacies, principally assuming but not proving, that the liquids involved are conjugate, indicate that these coefficients are merely an expression of the preference of certain elements for particular liquids, regardless of how the liquids formed. Proof of consanguinity in alkaline complexes requires more accurate age determinations on the relevant rock types than has generally been the case, and in most complexes, consanguinity can be discounted. We dispute the contention that melt inclusions represent parental melts, although they might elucidate the character of magmas undergoing fractional crystallization from magmatic to carbothermal stages. Radiogenic isotope data are shown to be too widely variable to support a case for liquid immiscibility. We address the contention that calcite cannot crystallize from a dolomitic liquid formed by direct mantle melting, and must therefore have crystallized from a calcite carbonate liquid generated by liquid immiscibility, and demonstrate that it is an unsupported hypothesis as calcite can readily crystallize from dolomitic liquids. We observe that, because immiscible dolomite liquids have never been produced experimentally, the liquid immiscibility proposition could at best be applied only to calcite carbonatites, thus leaving unexplained the large number of dolomite carbonatites and those of either type, which are not accompanied by alkaline silicate rocks. The assumed bimodality of alkaline-rock carbonatite complexes is considered to be fallacious and no actual geological or petrographic evidence for immiscibility processes is evident in these complexes. Several examples of alkaline rock carbonatite complexes for which immiscibility has been proposed are evaluated critically and shown to fail in attempts to establish them as exemplifying immiscibility. We conclude that no actual geological or experimental data exist to establish liquid immiscibility being involved in the genesis of calcite or dolomite carbonatite-forming magmas.

Placental thickness and its relationship to gestational age and fetal growth parameters in normal singleton pregnancies in the central region of Togo

Introduction: Accurate determination of gestational age (GA) is necessary for qualitative obstetric care, and ultrasound fetal biometry parameters are used when the last menstrual period is not known. The aim of this study was to measure by ultrasound the placental thickness (PT) and correlate it with GA and fetal growth parameters. Population and Methods: This was a descriptive cross-sectional study conducted in the Radiology and Medical Imaging Department of Sokode Regional Hospital. All low-risk pregnancies from the 11th week were included. Excel and R 4.2.2 software were used. A significance level of 5% was established for the statistical tests. Results: A total of 256 pregnancies were recorded. The mean of PT was 29.89 ± 7.42 mm. The mean of PT in the first, second, and third trimesters was 13.50 ± 3.67 mm, 24.61 ± 4.12 mm, and 34.65 ± 4.17 mm, respectively. There was a strong positive linear correlation between PT and GA (r = 0.87, P < 0.00001) and between PT and estimated fetal weight (EFW) (r = 0.80, P < 0.00001). The linear relationship between PT and GA could be expressed by the equation: GA = 0.894*PT-0.103. Similarly, the linear relationship between PT and EFW could be expressed by the equation EFW = 127.314*PT-2563.561. There was a strong linear correlation between PT and parameters such as biparietal diameter (r = 0.88, P < 0.00001), head circumference (r = 0.89, P < 0.00001), and femur length (r = 0.89, P < 0.00001). Conclusions: This study demonstrated a correlation between PT and fetal growth parameters, suggesting that PT can be utilized to monitor fetal growth.

Foetal Kidney Length as a Criterion for Gestational Age Estimation

Gestational Age (GA) is important because it helps guide prenatal care. The foetus plays a pivotal role in assessing its progress and establishing the anticipated delivery date. As GA increases, standard biometric markers like biparietal diameter, head circumference, and foetal length become less accurate, making accurate determination of Foetal Gestational Age (FGA) a significant barrier for patient care. The accuracy of Foetal Kidney Length (FKL) in predicting FGA in the third trimester has been established in several populations. The growth of foetal kidneys is linear with GA, and they are easily identifiable around 18 weeks, following the mid-trimester. The present paper discusses various related research, including the relationship between GA and the length of the foetal kidney.

Accuracy of Trans-Cerebellar Diameter and Placental Thickness in Third Trimesteric Pregnant Women for Calculation of Gestational Age: A Cross Sectional Study

Background: Accurate determination of gestational age has become important for deciding the appropriate time for termination of the pregnancy as well as to monitor the fetal growth during the entire period of pregnancy. Objective: The aim of the study was to assess whether the trans-cerebellar diameter, placental thickness or combining both of them is more accurate for assessment of gestational age in the 3rd trimester of pregnancy. Patients and Methods: This is a cross sectional study conducted at outpatient Clinic and Obstetric ward, Ain Shams University Maternity Hospital, over a period of six months from March 2019 to September 2019. One hundred pregnant women were recruited according to inclusion criteria either from outpatient clinic or were admitted in obstetric ward Ain Shams Maternity Hospital to find out the most accurate fetal biometric measurement in the third trimester either trans-cerebellar diameter placental thickness or both compared to reliable LMP (last menstrual period) dates confirmed by crown rump length (CRL) in the first trimester. Results: Trans-cerebellar diameter mean ± SD was 46.0 ± 3.5 with range 38.2 - 51.7. The mean of placental thickness was 39.6 ± 7.1 with range 22.8 - 54.3. Placental thickness had highest determination (0.813) for last menstrual period followed by trans-cerebellar diameter (0.802). Combining trans-cerebellar diameter and placental thickness increased determination (0.902) for last menstrual period. Conclusion: Combined use of trans-cerebellar diameter and placental thickness in the third trimester of pregnancy is a reliable indicator for gestational age in women whose last menstrual period is unreliable or unknown, but placental thickness had higher accuracy than trans-cerebellar diameter.

Evaluating the stage of deep vein thrombosis: the diagnostic accuracy of shear wave elastography and super-microvascular imaging.

Assessing the age of deep vein thrombosis (DVT) is crucial for guiding treatment approaches. Two-dimensional shear-wave elastography (2D-SWE) and super-microvascular imaging (SMI), as emerging techniques for tissue elasticity assessment and intrathrombus microvascular analysis, are pivotal for accurate thrombus age determination. This research endeavors to classify DVT into acute, subacute, and chronic ages utilizing these imaging methods. The study is a prospective, single-center, inpatient investigation that utilized convenience sampling for participant recruitment. Patients with a symptom duration of <6 months who were found to have lower-extremity DVT on ultrasound (US) between January 2021 and March 2022 after craniocerebral trauma (CT) or bone injury (BI) operations were included in this study. Participants were divided into three groups based on the duration of DVT, measured from the first diagnosis of thrombosis by US to the follow-up with 2D-SWE and SMI: acute (≤14 days), subacute (15-30 days), and chronic (31 days to 6 months) All patients underwent 2D-SWE and SMI using an Aplio i700 Ultrasound System equipped with a PLT-1005BT line array probe. Diagnostic performance was assessed using the area under the receiver operating characteristic (ROC) curve. The maximum value of the elastic modulus for DVT (DVT_Emax), the mean value of the elastic modulus for DVT (DVT_Emean), and SMI's flow distribution scoring pattern for DVT (SMI_scoring) emerged as significant predictors for acute and chronic, with high area under the ROC curve (AUC) of acute [AUC (95% confidential interval): 0.95 (0.89-0.97), 0.96 (0.91-0.98), 0.93 (0.88-0.97) in 39 patients] and chronic [AUC (95% confidential interval): 0.88 (0.81-0.93), 0.94 (0.88-0.97), 0.91 (0.84-0.95) in 51 patients], respectively. However, these indices had lower efficacy for subacute prediction [AUC (95% confidential interval): 0.51 (0.42-0.60), 0.54 (0.46-0.63), 0.53 (0.44-0.62), in 47 patients]. Combining DVT_Emean with SMI_scoring improved performance in predicting subacute: 0.90 (0.83-0.94) than related features alone. Both 2D-SWE and SMI can be used to assess acute and chronic DVT in patients with CT and BI after surgeries. This combination is a promising adjunctive technique for identifying the subacute phase of DVT in these patients.

Towards a new era in giant exoplanet characterisation

Determining the composition of giant exoplanets is crucial for understanding their origin and evolution. However, planetary bulk composition is not measured directly but must be deduced from a combination of mass-radius measurements, knowledge of the planetary age and evolution simulations. Accurate determinations of stellar ages, mass-radius measurements, and atmospheric compositions from upcoming missions can significantly improve the determination of the heavy-element mass in giant planets. In this paper we first demonstrate the importance of an accurate age measurement, as expected from Plato, in constraining planetary properties. Well-determined stellar ages can reduce the bulk-metallicity uncertainty by up to a factor of two. We next infer the bulk metallicity of warm giants from the Ariel mission reference sample and identify the Ariel high-priority targets for which a measured atmospheric metallicity can clearly break the degeneracy in the inferred composition. We show that knowledge of the atmospheric metallicity can broadly reduce the bulk-metallicity uncertainty by a factor of four to eight. We conclude that accurate age determinations from Plato and atmospheric measurements by Ariel and the James Webb Space Telescope will play a key role in revealing the composition of giant exoplanets.

An epigenetic DNA methylation clock for age estimates in Indo-Pacific bottlenose dolphins (Tursiops aduncus).

Knowledge of an animal's chronological age is crucial for understanding and predicting population demographics, survival and reproduction, but accurate age determination for many wild animals remains challenging. Previous methods to estimate age require invasive procedures, such as tooth extraction to analyse growth layers, which are difficult to carry out with large, mobile animals such as cetaceans. However, recent advances in epigenetic methods have opened new avenues for precise age determination. These 'epigenetic clocks' present a less invasive alternative and can provide age estimates with unprecedented accuracy. Here, we present a species-specific epigenetic clock based on skin tissue samples for a population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia. We measured methylation levels at 37,492 cytosine-guanine sites (CpG sites) in 165 samples using the mammalian methylation array. Chronological age estimates with an accuracy of ±1 year were available for 68 animals as part of a long-term behavioral study of this population. Using these samples with known age, we built an elastic net model with Leave-One-Out-Cross-Validation, which retained 43 CpG sites, providing an r= 0.86 and median absolute age error (MAE)=2.1 years (5% of maximum age). This model was more accurate for our data than the previously published methylation clock based on skin samples of common bottlenose dolphins (T. truncatus: r= 0.83, MAE=2.2) and the multi-species odontocete methylation clock (r= 0.68, MAE=6.8), highlighting that species-specific clocks can have superior performance over those of multi-species assemblages. We further developed an epigenetic sex estimator, predicting sex with 100% accuracy. As age and sex are critical parameters for the study of animal populations, this clock and sex estimator will provide a useful tool for extracting life history information from skin samples rather than long-term observational data for free-ranging Indo-Pacific bottlenose dolphins worldwide.

Unsure Last Normal Menstrual Period among Pregnant Women in Low Resource Setting: The Experience from Federal Teaching Hospital Gombe, North-Eastern Nigeria

Background: The proper management of any pregnancy depends on the accurate determination of the gestational age. In resource constrained environment where imaging techniques may not be readily available, accessible and affordable, the knowledge of menstrual period is key. Unfortunately, some of the pregnant women at antenatal clinics do not know their last normal menstrual period (LNMP). Aim/Objectives: This research was designed to ascertain the proportion of women who do not know their LNMP and associated factors. Materials and Methods: This was a descriptive, cross-sectional study involving antenatal attendees at the booking clinic of the Federal Teaching Hospital Gombe. Data such as socio-demographics, knowledge of dates/associated factors and willingness to remember the menstrual period subsequently was collected through a structured questionnaire from 1st March to 31st August 2022 and analysis done with IBM® SPSS® statistical Inc., Armonk, New York, USA software version 25 for analysis. Qui-square used as a test of statistics and the results presented in charts, graphs and tables. Results: Out of the 350 respondents 181(51.7%) knew their LNMP, while 169(48.3%) did not know. However, as much as 70.6% of the respondents knew that LNMP is used to date pregnancy. Reasons for not knowing dates included; not just keeping records of dates (25.4%), ignorance of Gregorian calendar (13.0%), on contraceptives when pregnancy was identified (10.7%), no reason (8.3%), was breastfeeding (6.5%), among several others. Surprisingly, 32% did not know the problems that may arise due to ignorance of LNMP. Majority (90.0%) of the respondents are willing to remember their LNMP in the next pregnancy. Women ≤ 19years and ≥ 40 years (p=0.004), lower level of education (p=0.004), Grand-multiparity (p=0.035), more than 4 living children (p=0.02) and rural dwellers (p=0.001) were more likely not to know their LNMP. Conclusion: The study showed 48.3% of the women were ignorant of their LNMP. The associated factors were extreme of ages, low level of education, grand multi-parity, having more than 4 living children and rural place of residence. Going forward, majority of the women accepted to remember their LNMP.

Age Determination in Children Using Camirere\'s Indian Specific Formula: A Radiographic Study Using Orthopantomographs

Determination of age is a pivotal part of forensic dentistry. Since many dental age determination methods are invasive, Cameriere introduced a radiographic method where age evaluation was carried out using an orthopantomogram (OPG). An adaptation of the same formula was later formulated by Rai et al. for the Indian population. The aim of the study was to assess the age and to dictate the efficiency of the Indian version of Cameriere's formula in the Chennai subpopulation. This study consisted of radiographs belonging to 50 individuals with an age range of 5-15 years. Radiographs were taken using the OPG and the soft copies obtained were analyzed. The variables such as seven left and right permanent mandibular teeth and the number of teeth with closed apical, and with open apical, ends of roots were examined and measured. The obtained data, after substituting in the formula was statistically analyzed using paired and unpaired t-test and Pearson's correlation coefficient test. On comparing dental age and chronological age, statistically significant results were obtained on both sides of the radiograph. Between genders, both sides of the radiograph showed non-significant results. On correlating the sides, the left side showed greater accuracy in age determination compared to the right side of the OPG. Age estimation using Indian-specified formula provides a near good estimate and hence can be a reliable method to measure the chronological age of the participants. The Indian version of the Cameriere's formula can be used as a rational tool to assess the age of young children and adolescents.

Estimating Age Using Nationwide Survey Data on the Number of Residual Teeth

Given that tooth loss is a degenerative change, the number of residual teeth may be used to specify a particular age range as a marker for age estimation. This study examined changes in the number of teeth with age using a nationwide oral survey database and derived the age distribution of the Korean population according to the number of teeth. Data on the number of teeth and age were extracted from the oral examination data of the Korean National Health and Nutrition Examination Survey (KNHANES) from 2016 to 2018. Statistical analyses of a complex sample survey were performed using weighted values. The distribution range of the number of teeth by age was broad. The proportion of young people decreased progressively as the number of remaining teeth decreased. In contrast, the proportion of those from the older age group decreased slightly as the number of teeth increased. The number of teeth was subdivided into groups of four, age was categorized into 5-year intervals, and the distribution of age groups by the number of teeth was analyzed. We attempted to determine the age group threshold at approximately 95th percentile for age. In summary, we found that if there were ≤4, 5-12, and 13-20 residual teeth, the estimated age was ≥60, ≥55, and ≥50 years, respectively, with an approximately 95% probability. When many teeth are lost and it is difficult to apply conventional dental age estimation methods, our method may assist in narrowing the age range, although it is not an accurate age determination method.