Epigenetic estimation of age in humpback whales

PubMed Central

Polanowski, Andrea M; Robbins, Jooke; Chandler, David; Jarman, Simon N

2014-01-01

Age is a fundamental aspect of animal ecology, but is difficult to determine in many species. Humpback whales exemplify this as they have a lifespan comparable to humans, mature sexually as early as 4 years and have no reliable visual age indicators after their first year. Current methods for estimating humpback age cannot be applied to all individuals and populations. Assays for human age have recently been developed based on age-induced changes in DNA methylation of specific genes. We used information on age-associated DNA methylation in human and mouse genes to identify homologous gene regions in humpbacks. Humpback skin samples were obtained from individuals with a known year of birth and employed to calibrate relationships between cytosine methylation and age. Seven of 37 cytosines assayed for methylation level in humpback skin had significant age-related profiles. The three most age-informative cytosine markers were selected for a humpback epigenetic age assay. The assay has an R2 of 0.787 (P = 3.04e−16) and predicts age from skin samples with a standard deviation of 2.991 years. The epigenetic method correctly determined which of parent–offspring pairs is the parent in more than 93% of cases. To demonstrate the potential of this technique, we constructed the first modern age profile of humpback whales off eastern Australia and compared the results to population structure 5 decades earlier. This is the first epigenetic age estimation method for a wild animal species and the approach we took for developing it can be applied to many other nonmodel organisms. PMID:24606053

Effects of Age and Schooling on Intellectual Performance: Estimates Obtained from Analysis of Continuous Variation in Age and Length of Schooling

ERIC Educational Resources Information Center

Cliffordson, Christina; Gustafsson, Jan-Eric

2008-01-01

The effects of age and schooling on different aspects of intellectual performance, taking track of study into account, are investigated. The analyses were based on military enlistment test scores, obtained by 48,269 males, measuring Fluid ability (Gf), Crystallized intelligence (Gc), and General visualization (Gv) ability. A regression method,…

Molecular pathology and age estimation.

PubMed

Meissner, Christoph; Ritz-Timme, Stefanie

2010-12-15

Over the course of our lifetime a stochastic process leads to gradual alterations of biomolecules on the molecular level, a process that is called ageing. Important changes are observed on the DNA-level as well as on the protein level and are the cause and/or consequence of our 'molecular clock', influenced by genetic as well as environmental parameters. These alterations on the molecular level may aid in forensic medicine to estimate the age of a living person, a dead body or even skeletal remains for identification purposes. Four such important alterations have become the focus of molecular age estimation in the forensic community over the last two decades. The age-dependent accumulation of the 4977bp deletion of mitochondrial DNA and the attrition of telomeres along with ageing are two important processes at the DNA-level. Among a variety of protein alterations, the racemisation of aspartic acid and advanced glycation endproducs have already been tested for forensic applications. At the moment the racemisation of aspartic acid represents the pinnacle of molecular age estimation for three reasons: an excellent standardization of sampling and methods, an evaluation of different variables in many published studies and highest accuracy of results. The three other mentioned alterations often lack standardized procedures, published data are sparse and often have the character of pilot studies. Nevertheless it is important to evaluate molecular methods for their suitability in forensic age estimation, because supplementary methods will help to extend and refine accuracy and reliability of such estimates. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Estimating age-specific reproductive numbers-A comparison of methods.

PubMed

Moser, Carlee B; White, Laura F

2016-01-01

Large outbreaks, such as those caused by influenza, put a strain on resources necessary for their control. In particular, children have been shown to play a key role in influenza transmission during recent outbreaks, and targeted interventions, such as school closures, could positively impact the course of emerging epidemics. As an outbreak is unfolding, it is important to be able to estimate reproductive numbers that incorporate this heterogeneity and to use surveillance data that is routinely collected to more effectively target interventions and obtain an accurate understanding of transmission dynamics. There are a growing number of methods that estimate age-group specific reproductive numbers with limited data that build on methods assuming a homogenously mixing population. In this article, we introduce a new approach that is flexible and improves on many aspects of existing methods. We apply this method to influenza data from two outbreaks, the 2009 H1N1 outbreaks in South Africa and Japan, to estimate age-group specific reproductive numbers and compare it to three other methods that also use existing data from social mixing surveys to quantify contact rates among different age groups. In this exercise, all estimates of the reproductive numbers for children exceeded the critical threshold of one and in most cases exceeded those of adults. We introduce a flexible new method to estimate reproductive numbers that describe heterogeneity in the population.

Estimating ages of white-tailed deer: Age and sex patterns of error using tooth wear-and-replacement and consistency of cementum annuli

USGS Publications Warehouse

Samuel, Michael D.; Storm, Daniel J.; Rolley, Robert E.; Beissel, Thomas; Richards, Bryan J.; Van Deelen, Timothy R.

2014-01-01

The age structure of harvested animals provides the basis for many demographic analyses. Ages of harvested white-tailed deer (Odocoileus virginianus) and other ungulates often are estimated by evaluating replacement and wear patterns of teeth, which is subjective and error-prone. Few previous studies however, examined age- and sex-specific error rates. Counting cementum annuli of incisors is an alternative, more accurate method of estimating age, but factors that influence consistency of cementum annuli counts are poorly known. We estimated age of 1,261 adult (≥1.5 yr old) white-tailed deer harvested in Wisconsin and Illinois (USA; 2005–2008) using both wear-and-replacement and cementum annuli. We compared cementum annuli with wear-and-replacement estimates to assess misclassification rates by sex and age. Wear-and-replacement for estimating ages of white-tailed deer resulted in substantial misclassification compared with cementum annuli. Age classes of females were consistently underestimated, while those of males were underestimated for younger age classes but overestimated for older age classes. Misclassification resulted in an impression of a younger age-structure than actually was the case. Additionally, we obtained paired age-estimates from cementum annuli for 295 deer. Consistency of paired cementum annuli age-estimates decreased with age, was lower in females than males, and decreased as age estimates became less certain. Our results indicated that errors in the wear-and-replacement techniques are substantial and could impact demographic analyses that use age-structure information. 

Precision of four otolith techniques for estimating age of white perch from a thermally altered reservoir

USGS Publications Warehouse

Snow, Richard A.; Porta, Michael J.; Long, James M.

2018-01-01

The White Perch Morone americana is an invasive species in many Midwestern states and is widely distributed in reservoir systems, yet little is known about the species' age structure and population dynamics. White Perch were first observed in Sooner Reservoir, a thermally altered cooling reservoir in Oklahoma, by the Oklahoma Department of Wildlife Conservation in 2006. It is unknown how thermally altered systems like Sooner Reservoir may affect the precision of White Perch age estimates. Previous studies have found that age structures from Largemouth Bass Micropterus salmoides and Bluegills Lepomis macrochirus from thermally altered reservoirs had false annuli, which increased error when estimating ages. Our objective was to quantify the precision of White Perch age estimates using four sagittal otolith preparation techniques (whole, broken, browned, and stained). Because Sooner Reservoir is thermally altered, we also wanted to identify the best month to collect a White Perch age sample based on aging precision. Ages of 569 White Perch (20–308 mm TL) were estimated using the four techniques. Age estimates from broken, stained, and browned otoliths ranged from 0 to 8 years; whole‐view otolith age estimates ranged from 0 to 7 years. The lowest mean coefficient of variation (CV) was obtained using broken otoliths, whereas the highest CV was observed using browned otoliths. July was the most precise month (lowest mean CV) for estimating age of White Perch, whereas April was the least precise month (highest mean CV). These results underscore the importance of knowing the best method to prepare otoliths for achieving the most precise age estimates and the best time of year to obtain those samples, as these factors may affect other estimates of population dynamics.

Value of parents' estimates of children's developmental ages.

PubMed

Glascoe, F P; Sandler, H

1995-11-01

To determine whether parents' estimates of children's developmental ages can function as a prescreening technique. Parents of 234 children from birth to 77 months of age seeking well-child care in pediatric offices were queried in two separate studies. In the first study, parents were asked to give an estimate of their child's overall developmental age and, in the second study, to estimate ages in each of six developmental domains. Children were administered a range of screening measures of intelligence, speech-language, and adoptive behavior. The overall age-estimate, if less than chronologic age, was 75% sensitive to likely developmental problems and, if equal to or greater than chronologic age, was 90% specific in identifying children likely to have typical development. Age estimates for each developmental domain were 81% sensitive to likely developmental problems if less than chronologic age in the domains of fine motor, language, grass motor, or behavior, and 62% specific if equal to or greater than chronologic age. Estimates at or below chronologic age in receptive language or personal-social domains were 90% sensitive and 43% specific in identifying likely behavior problems. There were no differences in the accuracy of parents estimates on the basis of children's age, gender, race, parents' level of education, or parenting experience. Parents' overall age-estimates provided a sensitive and specific indicator of global developmental status, but insufficient information about strengths and weaknesses to enable focused referrals for services. In contrast, discrete patterns of age estimates in each developmental domain sensitively discriminated children with developmental versus behavioral problems, although specificity was limited. Age estimates appear to be a potentially helpful method for identifying a subset of children in need of thorough screening, although further research is needed on a larger sample given diagnostic rather than screening tests.

Estimating ages of Utah chubs by use of pectoral fin rays, otoliths, and scales

USGS Publications Warehouse

Griffin, Kayla M; Beard, Zachary S.; Flinders, John M.; Quist, Michael C.

2017-01-01

Utah chub Gila atraria is native to the Upper Snake River system in Wyoming and Idaho and to the Lake Bonneville Basin in Utah and southeastern Idaho. However, the Utah chub has been introduced into many other waterbodies in the western United States, where it competes with ecologically and economically important species. The objectives of this study were to evaluate between-reader precision and reader confidence in age estimates obtained from pectoral fin rays, lapilli (otoliths), asterisci (otoliths), and scales for Utah chubs collected from Henrys Lake, Idaho. Lapilli have been previously shown to provide accurate age estimates for Utah chubs; therefore, we sought to compare age estimates from fin rays, asterisci, and scales to those from lapilli. The between-reader coefficient of variation (CV) in age estimates was lowest and the percent of exact reader agreement (PA-0) was highest for pectoral fin rays (CV = 4.7, PA-0 = 74%), followed by scales (CV = 10.3, PA-0 = 52.3%), lapilli (CV = 11.6, PA-0 = 48.2%), and asterisci (CV = 13.0, PA-0 = 41.7%). Consensus age estimates from pectoral fin rays showed high concordance with consensus age estimates from lapilli. Our results indicate that pectoral fin rays provide the most precise age estimates for Utah chub. Pectoral fin rays are easily collected and processed and also provide age estimates without requiring fish sacrifice.

Proof of age required--estimating age in adults without birth records.

PubMed

Phillips, Christine; Narayanasamy, Shanti

2010-07-01

Many adults from refugee source countries do not have documents of birth, either because they have been lost in flight, or because the civil infrastructure is too fragile to support routine recording of birth. In Western countries, date of birth is used as a basic identifier, and access to services and support tends to be age regulated. Doctors are not infrequently asked to write formal reports estimating the true age of adult refugees; however, there are no existing guidelines to assist in this task. To provide an overview of methods to estimate age in living adults, and outline recommendations for best practice. Age should be estimated through physical examination; life history, matching local or national events with personal milestones; and existing nonformal documents. Accuracy of age estimation should be subject to three tests: biological plausibility, historical plausibility, and corroboration from reputable sources.

Improvement of age estimation using amino acid racemization in a case of pink teeth.

PubMed

Ohtani, S; Yamada, Y; Yamamoto, I

1998-03-01

Age was estimated from pink teeth using racemization of dentinal aspartic acid. Materials for identification were two lower second premolars. The body was determined to be that of a 40-year-old man; however, the age of the decedent had been estimated to be 29 and 30 years by the conventional method and 30 years from findings in the oral cavity. To clarify the cause of this difference, the powdered teeth were further washed in 0.01 mol/L hydrochloric acid. The racemization ratio (D/L ratio) of ordinary white teeth from persons of known age was slightly lower than that before washing, whereas that of the teeth used for identification was higher than before washing. The calculated age of the decedent using the racemization ratio of his teeth was between 36 and 37 years. These results suggest that age estimated from pink teeth is probably underestimated, but a more accurate age estimate can be obtained after adequate washing.

Combining facial dynamics with appearance for age estimation.

PubMed

Dibeklioglu, Hamdi; Alnajar, Fares; Ali Salah, Albert; Gevers, Theo

2015-06-01

Estimating the age of a human from the captured images of his/her face is a challenging problem. In general, the existing approaches to this problem use appearance features only. In this paper, we show that in addition to appearance information, facial dynamics can be leveraged in age estimation. We propose a method to extract and use dynamic features for age estimation, using a person's smile. Our approach is tested on a large, gender-balanced database with 400 subjects, with an age range between 8 and 76. In addition, we introduce a new database on posed disgust expressions with 324 subjects in the same age range, and evaluate the reliability of the proposed approach when used with another expression. State-of-the-art appearance-based age estimation methods from the literature are implemented as baseline. We demonstrate that for each of these methods, the addition of the proposed dynamic features results in statistically significant improvement. We further propose a novel hierarchical age estimation architecture based on adaptive age grouping. We test our approach extensively, including an exploration of spontaneous versus posed smile dynamics, and gender-specific age estimation. We show that using spontaneity information reduces the mean absolute error by up to 21%, advancing the state of the art for facial age estimation.

A new age-based formula for estimating weight of Korean children.

PubMed

Park, Jungho; Kwak, Young Ho; Kim, Do Kyun; Jung, Jae Yun; Lee, Jin Hee; Jang, Hye Young; Kim, Hahn Bom; Hong, Ki Jeong

2012-09-01

The objective of this study was to develop and validate a new age-based formula for estimating body weights of Korean children. We obtained body weight and age data from a survey conducted in 2005 by the Korean Pediatric Society that was performed to establish normative values for Korean children. Children aged 0-14 were enrolled, and they were divided into three groups according to age: infants (<12 months), preschool-aged (1-4 years) and school-aged children (5-14 years). Seventy-five percent of all subjects were randomly selected to make a derivation set. Regression analysis was performed in order to produce equations that predict the weight from the age for each group. The linear equations derived from this analysis were simplified to create a weight estimating formula for Korean children. This formula was then validated using the remaining 25% of the study subjects with mean percentage error and absolute error. To determine whether a new formula accurately predicts actual weights of Korean children, we also compared this new formula to other weight estimation methods (APLS, Shann formula, Leffler formula, Nelson formula and Broselow tape). A total of 124,095 children's data were enrolled, and 19,854 (16.0%), 40,612 (32.7%) and 63,629 (51.3%) were classified as infants, preschool-aged and school-aged groups, respectively. Three equations, (age in months+9)/2, 2×(age in years)+9 and 4×(age in years)-1 were derived for infants, pre-school and school-aged groups, respectively. When these equations were applied to the validation set, the actual average weight of those children was 0.4kg heavier than our estimated weight (95% CI=0.37-0.43, p<0.001). The mean percentage error of our model (+0.9%) was lower than APLS (-11.5%), Shann formula (-8.6%), Leffler formula (-1.7%), Nelson formula (-10.0%), Best Guess formula (+5.0%) and Broselow tape (-4.8%) for all age groups. We developed and validated a simple formula to estimate body weight from the age of Korean

Revised age estimates of the Euphrosyne family

NASA Astrophysics Data System (ADS)

Carruba, Valerio; Masiero, Joseph R.; Cibulková, Helena; Aljbaae, Safwan; Espinoza Huaman, Mariela

2015-08-01

The Euphrosyne family, a high inclination asteroid family in the outer main belt, is considered one of the most peculiar groups of asteroids. It is characterized by the steepest size frequency distribution (SFD) among families in the main belt, and it is the only family crossed near its center by the ν6 secular resonance. Previous studies have shown that the steep size frequency distribution may be the result of the dynamical evolution of the family.In this work we further explore the unique dynamical configuration of the Euphrosyne family by refining the previous age values, considering the effects of changes in shapes of the asteroids during YORP cycle (``stochastic YORP''), the long-term effect of close encounters of family members with (31) Euphrosyne itself, and the effect that changing key parameters of the Yarkovsky force (such as density and thermal conductivity) has on the estimate of the family age obtained using Monte Carlo methods. Numerical simulations accounting for the interaction with the local web of secular and mean-motion resonances allow us to refine previous estimates of the family age. The cratering event that formed the Euphrosyne family most likely occurred between 560 and 1160 Myr ago, and no earlier than 1400 Myr ago when we allow for larger uncertainties in the key parameters of the Yarkovsky force.

Radiological age estimation: based on third molar mineralization and eruption in Turkish children and young adults.

PubMed

Karadayi, Beytullah; Kaya, Ahsen; Kolusayın, Melek Ozlem; Karadayi, Sükriye; Afsin, Hüseyin; Ozaslan, Abdi

2012-11-01

Radiographic evaluation of mineralization and eruption stages of third molars using dental panoramic radiographies can be an efficient tool for chronological age estimation in both forensic sciences and legal medicine. The third molar tooth is utilized for dental age estimation about the age span of 15-23 years because it represents the only tooth still in development. The aim of this study is to obtain and analyze data regarding third molar development and eruption in Turkish population for dental age estimation. A total of 744 dental panoramic radiographies of 394 female and 350 male subjects aged between 8 and 22 years were examined. Third molar development was determined according to the Nolla classification system, and eruption was assessed relative to the alveolar bone level. Mandibular and maxillary third molars were generally found at similar stages of development on both sides. Nolla stage 6 (completed crown calcification) was reached at around the age of 15 in both maxillary and mandibular third molars in both sexes. Alveolar emergence was at around the age of 16 in males and around age of 17 in females. Although third molars' eruption shows greater variability than development of third molars, data which were obtained from this study about eruption of these teeth can be supportive to development data for age estimation.

Bayesian calibration for forensic age estimation.

PubMed

Ferrante, Luigi; Skrami, Edlira; Gesuita, Rosaria; Cameriere, Roberto

2015-05-10

Forensic medicine is increasingly called upon to assess the age of individuals. Forensic age estimation is mostly required in relation to illegal immigration and identification of bodies or skeletal remains. A variety of age estimation methods are based on dental samples and use of regression models, where the age of an individual is predicted by morphological tooth changes that take place over time. From the medico-legal point of view, regression models, with age as the dependent random variable entail that age tends to be overestimated in the young and underestimated in the old. To overcome this bias, we describe a new full Bayesian calibration method (asymmetric Laplace Bayesian calibration) for forensic age estimation that uses asymmetric Laplace distribution as the probability model. The method was compared with three existing approaches (two Bayesian and a classical method) using simulated data. Although its accuracy was comparable with that of the other methods, the asymmetric Laplace Bayesian calibration appears to be significantly more reliable and robust in case of misspecification of the probability model. The proposed method was also applied to a real dataset of values of the pulp chamber of the right lower premolar measured on x-ray scans of individuals of known age. Copyright © 2015 John Wiley & Sons, Ltd.

Accurate age estimation in small-scale societies

PubMed Central

Smith, Daniel; Gerbault, Pascale; Dyble, Mark; Migliano, Andrea Bamberg; Thomas, Mark G.

2017-01-01

Precise estimation of age is essential in evolutionary anthropology, especially to infer population age structures and understand the evolution of human life history diversity. However, in small-scale societies, such as hunter-gatherer populations, time is often not referred to in calendar years, and accurate age estimation remains a challenge. We address this issue by proposing a Bayesian approach that accounts for age uncertainty inherent to fieldwork data. We developed a Gibbs sampling Markov chain Monte Carlo algorithm that produces posterior distributions of ages for each individual, based on a ranking order of individuals from youngest to oldest and age ranges for each individual. We first validate our method on 65 Agta foragers from the Philippines with known ages, and show that our method generates age estimations that are superior to previously published regression-based approaches. We then use data on 587 Agta collected during recent fieldwork to demonstrate how multiple partial age ranks coming from multiple camps of hunter-gatherers can be integrated. Finally, we exemplify how the distributions generated by our method can be used to estimate important demographic parameters in small-scale societies: here, age-specific fertility patterns. Our flexible Bayesian approach will be especially useful to improve cross-cultural life history datasets for small-scale societies for which reliable age records are difficult to acquire. PMID:28696282

Accurate age estimation in small-scale societies.

PubMed

Diekmann, Yoan; Smith, Daniel; Gerbault, Pascale; Dyble, Mark; Page, Abigail E; Chaudhary, Nikhil; Migliano, Andrea Bamberg; Thomas, Mark G

2017-08-01

Precise estimation of age is essential in evolutionary anthropology, especially to infer population age structures and understand the evolution of human life history diversity. However, in small-scale societies, such as hunter-gatherer populations, time is often not referred to in calendar years, and accurate age estimation remains a challenge. We address this issue by proposing a Bayesian approach that accounts for age uncertainty inherent to fieldwork data. We developed a Gibbs sampling Markov chain Monte Carlo algorithm that produces posterior distributions of ages for each individual, based on a ranking order of individuals from youngest to oldest and age ranges for each individual. We first validate our method on 65 Agta foragers from the Philippines with known ages, and show that our method generates age estimations that are superior to previously published regression-based approaches. We then use data on 587 Agta collected during recent fieldwork to demonstrate how multiple partial age ranks coming from multiple camps of hunter-gatherers can be integrated. Finally, we exemplify how the distributions generated by our method can be used to estimate important demographic parameters in small-scale societies: here, age-specific fertility patterns. Our flexible Bayesian approach will be especially useful to improve cross-cultural life history datasets for small-scale societies for which reliable age records are difficult to acquire.

Human age estimation combining third molar and skeletal development.

PubMed

Thevissen, P W; Kaur, J; Willems, G

2012-03-01

The wide prediction intervals obtained with age estimation methods based on third molar development could be reduced by combining these dental observations with age-related skeletal information. Therefore, on cephalometric radiographs, the most accurate age-estimating skeletal variable and related registration method were searched and added to a regression model, with age as response and third molar stages as explanatory variable. In a pilot set up on a dataset of 496 (283 M; 213 F) cephalometric radiographs, the techniques of Baccetti et al. (2005) (BA), Seedat et al. (2005) (SE), Caldas et al. (2007) and Rai et al. (2008) (RA) were verified. In the main study, data from 460 (208 F, 224 M) individuals in an age range between 3 and 26 years, for which at the same day an orthopantogram and a cephalogram were taken, were collected. On the orthopantomograms, the left third molar development was registered using the scoring system described by Gleiser and Hunt (1955) and modified by Köhler (1994) (GH). On the cephalograms, cervical vertebrae development was registered according to the BA and SE techniques. A regression model, with age as response and the GH scores as explanatory variable, was fitted to the data. Next, information of BA, SE and BA + SE was, respectively, added to this model. From all obtained models, the determination coefficients and the root mean squared errors were calculated. Inclusion of information from cephalograms based on the BA, as well as the SE, technique improved the amount of explained variance in age acquired from panoramic radiographs using the GH technique with 48%. Inclusion of cephalometric BA + SE information marginally improved the previous result (+1%). The RMSE decreased with 1.93, 1.85 and 2.03 years by adding, respectively, BA, SE and BA + SE information to the GH model. The SE technique allows clinically the fastest and easiest registration of the degree of development of the cervical vertebrae. Therefore, the choice of

Estimating stand age for Douglas-fir.

Treesearch

Floyd A. Johnson

1954-01-01

Stand age for Douglas-fir has been defined as the average age of dominant and codominant trees. It is commonly estimated by measuring the age of several dominants and codominants and computing their arithmetic average.

Age estimation by using dental radiographs

PubMed Central

Limdiwala, Piyush G.; Shah, J. S.

2013-01-01

Background: Estimation of age is important in forensic sciences as a way to establish the identity of human remains. Of the various parts of the body used in age estimation, teeth are the least affected by the taphonomic process. Their durability means that they are sometimes the only body part available for study. Several methods of age estimation have been studied using bone and teeth, and among them, tooth wear and apposition of secondary dentine are the currently available non-destructive methods. Objectives: The purpose of the study was to determine the age of adults by using Kvaal's method as well as to establish the relationship of chronological age and dental age with its reliability and limitations on digital panoramic radiographs. Materials and Methods: The present study was based on panoramic radiographs that consisted of two groups. One hundred orthopantomographs with Kvaal's criteria (Group A) and 50 orthopantomographs without Kvaal's criteria (Group B) were included. Various parameters were measured and the result was analyzed by means of SPSS-12.0 program statistical data. Result and Conclusion: On the basis of Kvaal's criteria, the difference between chronological age and real age was 8.3 years. This suggests that the accuracy of this method depends on the precision of measurements and quality and number of the orthopantomographs. PMID:24255560

Facial Asymmetry-Based Age Group Estimation: Role in Recognizing Age-Separated Face Images.

PubMed

Sajid, Muhammad; Taj, Imtiaz Ahmad; Bajwa, Usama Ijaz; Ratyal, Naeem Iqbal

2018-04-23

Face recognition aims to establish the identity of a person based on facial characteristics. On the other hand, age group estimation is the automatic calculation of an individual's age range based on facial features. Recognizing age-separated face images is still a challenging research problem due to complex aging processes involving different types of facial tissues, skin, fat, muscles, and bones. Certain holistic and local facial features are used to recognize age-separated face images. However, most of the existing methods recognize face images without incorporating the knowledge learned from age group estimation. In this paper, we propose an age-assisted face recognition approach to handle aging variations. Inspired by the observation that facial asymmetry is an age-dependent intrinsic facial feature, we first use asymmetric facial dimensions to estimate the age group of a given face image. Deeply learned asymmetric facial features are then extracted for face recognition using a deep convolutional neural network (dCNN). Finally, we integrate the knowledge learned from the age group estimation into the face recognition algorithm using the same dCNN. This integration results in a significant improvement in the overall performance compared to using the face recognition algorithm alone. The experimental results on two large facial aging datasets, the MORPH and FERET sets, show that the proposed age group estimation based on the face recognition approach yields superior performance compared to some existing state-of-the-art methods. © 2018 American Academy of Forensic Sciences.

Dental Age Estimation Helps Create a New Identity.

PubMed

De Angelis, Danilo; Gibelli, Daniele; Fabbri, Paolo; Cattaneo, Cristina

2015-09-01

Age estimation involves the reconstruction of age by biological parameters such as skeletal and dental development in minors, or reduction of pulp chamber in adults, to gain indications concerning the chronological age of the person. In most cases, it is needed in forensic scenarios to verify if the supposed age of an individual is correct; in exceptional cases, age estimation is instead required by judicial authorities to create a new identity usually in persons who do not remember who they are.This article aims at reporting the case of J. who was found in 2005 with signs of amnesia because he did not remember his name and age. After several unsuccessful attempts at identifying him, the judicial authority decided to assign a new identity, which was to be constructed according to the real biological data of the individual. The help of a forensic pathologist and a forensic odontologist was then requested, and age estimation was reached by applying methods for adults based on the physiological reduction of pulp chamber. Dental age estimation yielded a final result of approximately 31 years, which was the new age assigned to the person.This article shows a peculiar application of dental age estimation, which can be used not only to ascertain or deny supposed age, but is sometimes needed to create a new identity.

Reliability of third molar development for age estimation in Gujarati population: A comparative study.

PubMed

Gandhi, Neha; Jain, Sandeep; Kumar, Manish; Rupakar, Pratik; Choyal, Kanaram; Prajapati, Seema

2015-01-01

Age assessment may be a crucial step in postmortem profiling leading to confirmative identification. In children, Demirjian's method based on eight developmental stages was developed to determine maturity scores as a function of age and polynomial functions to determine age as a function of score. Of this study was to evaluate the reliability of age estimation using Demirjian's eight teeth method following the French maturity scores and Indian-specific formula from developmental stages of third molar with the help of orthopantomograms using the Demirjian method. Dental panoramic tomograms from 30 subjects each of known chronological age and sex were collected and were evaluated according to Demirjian's criteria. Age calculations were performed using Demirjian's formula and Indian formula. Statistical analysis used was Chi-square test and ANOVA test and the P values obtained were statistically significant. There was an average underestimation of age with both Indian and Demirjian's formulas. The mean absolute error was lower using Indian formula hence it can be applied for age estimation in present Gujarati population. Also, females were ahead of achieving dental maturity than males thus completion of dental development is attained earlier in females. Greater accuracy can be obtained if population-specific formulas considering the ethnic and environmental variation are derived performing the regression analysis.

Dental age estimation of growing children by measurement of open apices: A Malaysian formula

PubMed Central

Cugati, Navaneetha; Kumaresan, Ramesh; Srinivasan, Balamanikanda; Karthikeyan, Priyadarshini

2015-01-01

Background: Age estimation is of prime importance in forensic science and clinical dentistry. Age estimation based on teeth development is one reliable approach. Many radiographic methods are proposed on the Western population for estimating dental age, and a similar assessment was found to be inadequate in Malaysian population. Hence, this study aims at formulating a regression model for dental age estimation in Malaysian children population using Cameriere's method. Materials and Methods: Orthopantomographs of 421 Malaysian children aged between 5 and 16 years involving all the three ethnic origins were digitalized and analyzed using Cameriere's method of age estimation. The subjects’ age was modeled as a function of the morphological variables, gender (g), ethnicity, sum of normalized open apices (s), number of tooth with completed root formation (N0) and the first-order interaction between s and N0. Results: The variables that contributed significantly to the fit were included in the regression model, yielding the following formula: Age = 11.368-0.345g + 0.553No -1.096s - 0.380s.No, where g is a variable, 1 for males and 2 for females. The equation explained 87.1% of total deviance. Conclusion: The results obtained insist on reframing the original Cameriere's formula to suit the population of the nation specifically. Further studies are to be conducted to evaluate the applicability of this formula on a larger sample size. PMID:26816464

Reliability of third molar development for age estimation in Gujarati population: A comparative study

PubMed Central

Gandhi, Neha; Jain, Sandeep; Kumar, Manish; Rupakar, Pratik; Choyal, Kanaram; Prajapati, Seema

2015-01-01

Background: Age assessment may be a crucial step in postmortem profiling leading to confirmative identification. In children, Demirjian's method based on eight developmental stages was developed to determine maturity scores as a function of age and polynomial functions to determine age as a function of score. Aim: Of this study was to evaluate the reliability of age estimation using Demirjian's eight teeth method following the French maturity scores and Indian-specific formula from developmental stages of third molar with the help of orthopantomograms using the Demirjian method. Materials and Methods: Dental panoramic tomograms from 30 subjects each of known chronological age and sex were collected and were evaluated according to Demirjian's criteria. Age calculations were performed using Demirjian's formula and Indian formula. Statistical analysis used was Chi-square test and ANOVA test and the P values obtained were statistically significant. Results: There was an average underestimation of age with both Indian and Demirjian's formulas. The mean absolute error was lower using Indian formula hence it can be applied for age estimation in present Gujarati population. Also, females were ahead of achieving dental maturity than males thus completion of dental development is attained earlier in females. Conclusion: Greater accuracy can be obtained if population-specific formulas considering the ethnic and environmental variation are derived performing the regression analysis. PMID:26005298

A holistic approach to age estimation in refugee children.

PubMed

Sypek, Scott A; Benson, Jill; Spanner, Kate A; Williams, Jan L

2016-06-01

Many refugee children arriving in Australia have an inaccurately documented date of birth (DOB). A medical assessment of a child's age is often requested when there is a concern that their documented DOB is incorrect. This study's aim was to assess the accuracy a holistic age assessment tool (AAT) in estimating the age of refugee children newly settled in Australia. A holistic AAT that combines medical and non-medical approaches was used to estimate the ages of 60 refugee children with a known DOB. The tool used four components to assess age: an oral narrative, developmental assessment, anthropometric measures and pubertal assessment. Assessors were blinded to the true age of the child. Correlation coefficients for the actual and estimated age were calculated for the tool overall and individual components. The correlation coefficient between the actual and estimated age from the AAT was very strong at 0.9802 (boys 0.9748, girls 0.9876). The oral narrative component of the tool performed best (R = 0.9603). Overall, 86.7% of age estimates were within 1 year of the true age. The range of differences was -1.43 to 3.92 years with a standard deviation of 0.77 years (9.24 months). The AAT is a holistic, simple and safe instrument that can be used to estimate age in refugee children with results comparable with radiological methods currently used. © 2016 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).

Utilization of bone impedance for age estimation in postmortem cases.

PubMed

Ishikawa, Noboru; Suganami, Hideki; Nishida, Atsushi; Miyamori, Daisuke; Kakiuchi, Yasuhiro; Yamada, Naotake; Wook-Cheol, Kim; Kubo, Toshikazu; Ikegaya, Hiroshi

2015-11-01

In the field of Forensic Medicine the number of unidentified cadavers has increased due to natural disasters and international terrorism. The age estimation is very important for identification of the victims. The degree of sagittal closure is one of such age estimation methods. However it is not widely accepted as a reliable method for age estimation. In this study, we have examined whether measuring impedance value (z-values) of the sagittal suture of the skull is related to the age in men and women and discussed the possibility to use bone impedance for age estimation. Bone impedance values increased with aging and decreased after the age of 64.5. Then we compared age estimation through the conventional visual method and the proposed bone impedance measurement technique. It is suggested that the bone impedance measuring technique may be of value to forensic science as a method of age estimation. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Calibrating recruitment estimates for mourning doves from harvest age ratios

USGS Publications Warehouse

Miller, David A.; Otis, David L.

2010-01-01

We examined results from the first national-scale effort to estimate mourning dove (Zenaida macroura) age ratios and developed a simple, efficient, and generalizable methodology for calibrating estimates. Our method predicted age classes of unknown-age wings based on backward projection of molt distributions from fall harvest collections to preseason banding. We estimated 1) the proportion of late-molt individuals in each age class, and 2) the molt rates of juvenile and adult birds. Monte Carlo simulations demonstrated our estimator was minimally biased. We estimated model parameters using 96,811 wings collected from hunters and 42,189 birds banded during preseason from 68 collection blocks in 22 states during the 2005–2007 hunting seasons. We also used estimates to derive a correction factor, based on latitude and longitude of samples, which can be applied to future surveys. We estimated differential vulnerability of age classes to harvest using data from banded birds and applied that to harvest age ratios to estimate population age ratios. Average, uncorrected age ratio of known-age wings for states that allow hunting was 2.25 (SD 0.85) juveniles:adult, and average, corrected ratio was 1.91 (SD 0.68), as determined from harvest age ratios from an independent sample of 41,084 wings collected from random hunters in 2007 and 2008. We used an independent estimate of differential vulnerability to adjust corrected harvest age ratios and estimated the average population age ratio as 1.45 (SD 0.52), a direct measure of recruitment rates. Average annual recruitment rates were highest east of the Mississippi River and in the northwestern United States, with lower rates between. Our results demonstrate a robust methodology for calibrating recruitment estimates for mourning doves and represent the first large-scale estimates of recruitment for the species. Our methods can be used by managers to correct future harvest survey data to generate recruitment estimates for use in

Discriminating Projections for Estimating Face Age in Wild Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokola, Ryan A; Bolme, David S; Ricanek, Karl

2014-01-01

We introduce a novel approach to estimating the age of a human from a single uncontrolled image. Current face age estimation algorithms work well in highly controlled images, and some are robust to changes in illumination, but it is usually assumed that images are close to frontal. This bias is clearly seen in the datasets that are commonly used to evaluate age estimation, which either entirely or mostly consist of frontal images. Using pose-specific projections, our algorithm maps image features into a pose-insensitive latent space that is discriminative with respect to age. Age estimation is then performed using a multi-classmore » SVM. We show that our approach outperforms other published results on the Images of Groups dataset, which is the only age-related dataset with a non-trivial number of off-axis face images, and that we are competitive with recent age estimation algorithms on the mostly-frontal FG-NET dataset. We also experimentally demonstrate that our feature projections introduce insensitivity to pose.« less

Estimating Gestational Age From Ultrasound Fetal Biometrics.

PubMed

Skupski, Daniel W; Owen, John; Kim, Sungduk; Fuchs, Karin M; Albert, Paul S; Grantz, Katherine L

2017-08-01

To compare the accuracy of a new formula with one developed in 1984 (and still in common use) and to develop and compare racial and ethnic-specific and racial and ethnic-neutral formulas. The Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies-Singletons was a prospective cohort study that recruited women in four self-reported racial-ethnic groups-non-Hispanic black, Hispanic, non-Hispanic white, and Asian-with singleton gestations from 12 U.S. centers (2009-2013). Women with a certain last menstrual period confirmed by first-trimester ultrasonogram had longitudinal fetal measurements by credentialed study ultrasonographers blinded to the gestational age at their five follow-up visits. Regression analyses were performed with linear mixed models to develop gestational age estimating formulas. Repeated cross-validation was used for validation. The estimation error was defined as the mean squared difference between the estimated and observed gestational age and was used to compare the formulas' accuracy. The new formula estimated the gestational age (±2 SD) within ±7 days from 14 to 20 weeks of gestation, ±10 days from 21 to 27 weeks of gestation, and ±17 days from 28 to 40 weeks of gestation. The new formula performed significantly better than a formula developed in 1984 with an estimation error of 10.4 compared with 11.2 days from 21 to 27 weeks of gestation and 17.0 compared with 19.8 days at 28-40 weeks of gestation, respectively. Racial and ethnic-specific formulas did not outperform the racial and ethnic-neutral formula. The NICHD gestational age estimation formula is associated with smaller errors than a well-established historical formula. Racial and ethnic-specific formulas are not superior to a racial-ethnic-neutral one.

Dental age estimation: the role of probability estimates at the 10 year threshold.

PubMed

Lucas, Victoria S; McDonald, Fraser; Neil, Monica; Roberts, Graham

2014-08-01

The use of probability at the 18 year threshold has simplified the reporting of dental age estimates for emerging adults. The availability of simple to use widely available software has enabled the development of the probability threshold for individual teeth in growing children. Tooth development stage data from a previous study at the 10 year threshold were reused to estimate the probability of developing teeth being above or below the 10 year thresh-hold using the NORMDIST Function in Microsoft Excel. The probabilities within an individual subject are averaged to give a single probability that a subject is above or below 10 years old. To test the validity of this approach dental panoramic radiographs of 50 female and 50 male children within 2 years of the chronological age were assessed with the chronological age masked. Once the whole validation set of 100 radiographs had been assessed the masking was removed and the chronological age and dental age compared. The dental age was compared with chronological age to determine whether the dental age correctly or incorrectly identified a validation subject as above or below the 10 year threshold. The probability estimates correctly identified children as above or below on 94% of occasions. Only 2% of the validation group with a chronological age of less than 10 years were assigned to the over 10 year group. This study indicates the very high accuracy of assignment at the 10 year threshold. Further work at other legally important age thresholds is needed to explore the value of this approach to the technique of age estimation. Copyright © 2014. Published by Elsevier Ltd.

A learning framework for age rank estimation based on face images with scattering transform.

PubMed

Chang, Kuang-Yu; Chen, Chu-Song

2015-03-01

This paper presents a cost-sensitive ordinal hyperplanes ranking algorithm for human age estimation based on face images. The proposed approach exploits relative-order information among the age labels for rank prediction. In our approach, the age rank is obtained by aggregating a series of binary classification results, where cost sensitivities among the labels are introduced to improve the aggregating performance. In addition, we give a theoretical analysis on designing the cost of individual binary classifier so that the misranking cost can be bounded by the total misclassification costs. An efficient descriptor, scattering transform, which scatters the Gabor coefficients and pooled with Gaussian smoothing in multiple layers, is evaluated for facial feature extraction. We show that this descriptor is a generalization of conventional bioinspired features and is more effective for face-based age inference. Experimental results demonstrate that our method outperforms the state-of-the-art age estimation approaches.

Estimating the age-specific duration of herpes zoster vaccine protection: a matter of model choice?

PubMed

Bilcke, Joke; Ogunjimi, Benson; Hulstaert, Frank; Van Damme, Pierre; Hens, Niel; Beutels, Philippe

2012-04-05

The estimation of herpes zoster (HZ) vaccine efficacy by time since vaccination and age at vaccination is crucial to assess the effectiveness and cost-effectiveness of HZ vaccination. Published estimates for the duration of protection from the vaccine diverge substantially, although based on data from the same trial for a follow-up period of 5 years. Different models were used to obtain these estimates, but it is unclear which of these models is most appropriate (if any). Only one study estimated vaccine efficacy by age at vaccination and time since vaccination combined. Recently, data became available from the same trial for a follow-up period of 7 years. We aim to elaborate on estimating HZ vaccine efficacy (1) by estimating it as a function of time since vaccination and age at vaccination, (2) by comparing the fits of a range of models, and (3) by fitting these models on data for a follow-up period of 5 and 7 years. Although the models' fit to data are very comparable, they differ substantially in how they estimate vaccine efficacy to change as a function of time since vaccination and age at vaccination. An accurate estimation of HZ vaccine efficacy by time since vaccination and age at vaccination is hampered by the lack of insight in the biological processes underlying HZ vaccine protection, and by the fact that such data are currently not available in sufficient detail. Uncertainty about the choice of model to estimate this important parameter should be acknowledged in cost-effectiveness analyses. Copyright © 2011 Elsevier Ltd. All rights reserved.

Heterogeneous Rates of Molecular Evolution and Diversification Could Explain the Triassic Age Estimate for Angiosperms.

PubMed

Beaulieu, Jeremy M; O'Meara, Brian C; Crane, Peter; Donoghue, Michael J

2015-09-01

Dating analyses based on molecular data imply that crown angiosperms existed in the Triassic, long before their undisputed appearance in the fossil record in the Early Cretaceous. Following a re-analysis of the age of angiosperms using updated sequences and fossil calibrations, we use a series of simulations to explore the possibility that the older age estimates are a consequence of (i) major shifts in the rate of sequence evolution near the base of the angiosperms and/or (ii) the representative taxon sampling strategy employed in such studies. We show that both of these factors do tend to yield substantially older age estimates. These analyses do not prove that younger age estimates based on the fossil record are correct, but they do suggest caution in accepting the older age estimates obtained using current relaxed-clock methods. Although we have focused here on the angiosperms, we suspect that these results will shed light on dating discrepancies in other major clades. ©The Author(s) 2015. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Age synthesis and estimation via faces: a survey.

PubMed

Fu, Yun; Guo, Guodong; Huang, Thomas S

2010-11-01

Human age, as an important personal trait, can be directly inferred by distinct patterns emerging from the facial appearance. Derived from rapid advances in computer graphics and machine vision, computer-based age synthesis and estimation via faces have become particularly prevalent topics recently because of their explosively emerging real-world applications, such as forensic art, electronic customer relationship management, security control and surveillance monitoring, biometrics, entertainment, and cosmetology. Age synthesis is defined to rerender a face image aesthetically with natural aging and rejuvenating effects on the individual face. Age estimation is defined to label a face image automatically with the exact age (year) or the age group (year range) of the individual face. Because of their particularity and complexity, both problems are attractive yet challenging to computer-based application system designers. Large efforts from both academia and industry have been devoted in the last a few decades. In this paper, we survey the complete state-of-the-art techniques in the face image-based age synthesis and estimation topics. Existing models, popular algorithms, system performances, technical difficulties, popular face aging databases, evaluation protocols, and promising future directions are also provided with systematic discussions.

Aging persons' estimates of vehicular motion.

PubMed

Schiff, W; Oldak, R; Shah, V

1992-12-01

Estimated arrival times of moving autos were examined in relation to viewer age, gender, motion trajectory, and velocity. Direct push-button judgments were compared with verbal estimates derived from velocity and distance, which were based on assumptions that perceivers compute arrival time from perceived distance and velocity. Experiment 1 showed that direct estimates of younger Ss were most accurate. Older women made the shortest (highly cautious) estimates of when cars would arrive. Verbal estimates were much lower than direct estimates, with little correlation between them. Experiment 2 extended target distances and velocities of targets, with the results replicating the main findings of Experiment 1. Judgment accuracy increased with target velocity, and verbal estimates were again poorer estimates of arrival time than direct ones, with different patterns of findings. Using verbal estimates to approximate judgments in traffic situations appears questionable.

Age estimation based on aspartic acid racemization in human sclera.

PubMed

Klumb, Karolin; Matzenauer, Christian; Reckert, Alexandra; Lehmann, Klaus; Ritz-Timme, Stefanie

2016-01-01

Age estimation based on racemization of aspartic acid residues (AAR) in permanent proteins has been established in forensic medicine for years. While dentine is the tissue of choice for this molecular method of age estimation, teeth are not always available which leads to the need to identify other suitable tissues. We examined the suitability of total tissue samples of human sclera for the estimation of age at death. Sixty-five samples of scleral tissue were analyzed. The samples were hydrolyzed and after derivatization, the extent of aspartic acid racemization was determined by gas chromatography. The degree of AAR increased with age. In samples from younger individuals, the correlation of age and D-aspartic acid content was closer than in samples from older individuals. The age-dependent racemization in total tissue samples proves that permanent or at least long-living proteins are present in scleral tissue. The correlation of AAR in human sclera and age at death is close enough to serve as basis for age estimation. However, the precision of age estimation by this method is lower than that of age estimation based on the analysis of dentine which is due to molecular inhomogeneities of total tissue samples of sclera. Nevertheless, the approach may serve as a valuable alternative or addition in exceptional cases.

Western Saudi adolescent age estimation utilising third molar development.

PubMed

Alshihri, Amin M; Kruger, Estie; Tennant, Marc

2014-07-01

The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage "H" most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results.

Western Saudi adolescent age estimation utilising third molar development

PubMed Central

Alshihri, Amin M.; Kruger, Estie; Tennant, Marc

2014-01-01

Objective: The aim of this study was to establish reference data on third molar morphology/development for age estimation in Western Saudi adolescents, between ages 14 and 23 years of old. Materials and Methods: The orthopantomograms of 130 individuals (males and females), were examined, and the stage of third molar development were evaluated. Results: Mean ages, standard deviations, and percentile distributions are presented for each stage of development. The mean estimated age for all participants (n = 130) was 219.7 months, and this differed significantly (P < 0.05) from the mean chronological age (226.5 months). Deviations of predicted age from real age showed 28.5% of all participants had their age estimated within 1 year (±12 months) of their chronological age. Most (43%) had their age underestimated by more than 12 months and the remaining 28.5% had their age overestimated by more than 12 months of their chronological age. Differences in left-right symmetry information of third molars were detected and were higher in the maxilla (92%) than in the mandible (82%). For all molars reaching stage “H” most individuals (males and females) were over the age 18 years of old. Males reach the developmental stages earlier than females. Conclusion: Third molar tooth development can be reliably used to generate mean age and the estimated age range for an individual of unknown chronological age. Further studies with large populations are needed for better statistical results. PMID:25202206

Estimation of Stratospheric Age Spectrum from Chemical Tracers

NASA Technical Reports Server (NTRS)

Schoeberl, Mark R.; Douglass, Anne R.; Polansky, Brian

2005-01-01

We have developed a technique to diagnose the stratospheric age spectrum and estimate the mean age of air using the distributions of at least four constituents with different photochemical lifetimes. We demonstrate that the technique works using a 3D CTM and then apply the technique to UMS CLAES January 1993 observations of CFC11, CFC12, CH4 and N2O. Our results are generally in agreement with mean age of air estimates from the chemical model and from observations of SF6 and CO2; however, the mean age estimates show an intrusion of very young tropical air into the mid-latitude stratosphere. This feature is consistent with mixing of high N20 air out of the tropics during the westerly phase of the QBO.

5 CFR 1650.41 - How to obtain an age-based withdrawal.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 5 Administrative Personnel 3 2011-01-01 2011-01-01 false How to obtain an age-based withdrawal... an age-based withdrawal. To request an age-based withdrawal, a participant must submit to the TSP record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to...

5 CFR 1650.41 - How to obtain an age-based withdrawal.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 5 Administrative Personnel 3 2013-01-01 2013-01-01 false How to obtain an age-based withdrawal... an age-based withdrawal. To request an age-based withdrawal, a participant must submit to the TSP record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to...

5 CFR 1650.41 - How to obtain an age-based withdrawal.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 5 Administrative Personnel 3 2012-01-01 2012-01-01 false How to obtain an age-based withdrawal... an age-based withdrawal. To request an age-based withdrawal, a participant must submit to the TSP record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to...

Age group estimation in free-ranging African elephants based on acoustic cues of low-frequency rumbles

PubMed Central

Stoeger, Angela S.; Zeppelzauer, Matthias; Baotic, Anton

2015-01-01

Animal vocal signals are increasingly used to monitor wildlife populations and to obtain estimates of species occurrence and abundance. In the future, acoustic monitoring should function not only to detect animals, but also to extract detailed information about populations by discriminating sexes, age groups, social or kin groups, and potentially individuals. Here we show that it is possible to estimate age groups of African elephants (Loxodonta africana) based on acoustic parameters extracted from rumbles recorded under field conditions in a National Park in South Africa. Statistical models reached up to 70 % correct classification to four age groups (infants, calves, juveniles, adults) and 95 % correct classification when categorising into two groups (infants/calves lumped into one group versus adults). The models revealed that parameters representing absolute frequency values have the most discriminative power. Comparable classification results were obtained by fully automated classification of rumbles by high-dimensional features that represent the entire spectral envelope, such as MFCC (75 % correct classification) and GFCC (74 % correct classification). The reported results and methods provide the scientific foundation for a future system that could potentially automatically estimate the demography of an acoustically monitored elephant group or population. PMID:25821348

Comparison of the precision of age estimates generated from fin rays, scales, and otoliths of Blue Sucker

USGS Publications Warehouse

Acre, Matthew R.; Alejandrez, Celeste; East, Jessica; Massure, Wade A.; Miyazono, S.; Pease, Jessica E.; Roesler, Elizabeth L.; Williams, H.M.; Grabowski, Timothy B.

2017-01-01

Evaluating the precision of age estimates generated by different readers and different calcified structures is an important part of generating reliable estimations of growth, recruitment, and mortality for fish populations. Understanding the potential loss of precision associated with using structures harvested without sacrificing individuals, such as scales or fin rays, is particularly important when working with imperiled species, such as Cycleptus elongatus (Blue Sucker). We collected otoliths (lapilli), scales, and the first fin rays of the dorsal, anal, pelvic, and pectoral fins of 9 Blue Suckers. We generated age estimates from each structure by both experienced (n = 5) and novice (n = 4) readers. We found that, independent of the structure used to generate the age estimates, the mean coefficient of variation (CV) of experienced readers was approximately 29% lower than that of novice readers. Further, the mean CV of age estimates generated from pectoral-fin rays, pelvic-fin rays, and scales were statistically indistinguishable and less than those of dorsal-fin rays, anal-fin rays, and otoliths. Anal-, dorsal-, and pelvic-fin rays and scales underestimated age compared to otoliths, but age estimates from pectoral-fin rays were comparable to those from otoliths. Skill level, structure, and fish total-length influenced reader precision between subsequent reads of the same aging structure from a particular fish. Using structures that can be harvested non-lethally to estimate the age of Blue Sucker can provide reliable and reproducible results, similar to those that would be expected from using otoliths. Therefore, we recommend the use of pectoral-fin rays as a non-lethal method to obtain age estimates for Blue Suckers.

Comparative study of age estimation using dentinal translucency by digital and conventional methods.

PubMed

Bommannavar, Sushma; Kulkarni, Meena

2015-01-01

Estimating age using the dentition plays a significant role in identification of the individual in forensic cases. Teeth are one of the most durable and strongest structures in the human body. The morphology and arrangement of teeth vary from person-to-person and is unique to an individual as are the fingerprints. Therefore, the use of dentition is the method of choice in the identification of the unknown. Root dentin translucency is considered to be one of the best parameters for dental age estimation. Traditionally, root dentin translucency was measured using calipers. Recently, the use of custom built software programs have been proposed for the same. The present study describes a method to measure root dentin translucency on sectioned teeth using a custom built software program Adobe Photoshop 7.0 version (Adobe system Inc, Mountain View California). A total of 50 single rooted teeth were sectioned longitudinally to derive a 0.25 mm uniform thickness and the root dentin translucency was measured using digital and caliper methods and compared. The Gustafson's morphohistologic approach is used in this study. Correlation coefficients of translucency measurements to age were statistically significant for both the methods (P < 0.125) and linear regression equations derived from both methods revealed better ability of the digital method to assess age. The custom built software program used in the present study is commercially available and widely used image editing software. Furthermore, this method is easy to use and less time consuming. The measurements obtained using this method are more precise and thus help in more accurate age estimation. Considering these benefits, the present study recommends the use of digital method to assess translucency for age estimation.

78 FR 6289 - Estimates of the Voting Age Population for 2012

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-30

... DEPARTMENT OF COMMERCE Office of the Secretary Estimates of the Voting Age Population for 2012... estimates. SUMMARY: This notice announces the voting age population estimates as of July 1, 2012, for each... notice that the estimates of the voting age population for July 1, 2012, for each state and the District...

Can you hear my age? Influences of speech rate and speech spontaneity on estimation of speaker age

PubMed Central

Skoog Waller, Sara; Eriksson, Mårten; Sörqvist, Patrik

2015-01-01

Cognitive hearing science is mainly about the study of how cognitive factors contribute to speech comprehension, but cognitive factors also partake in speech processing to infer non-linguistic information from speech signals, such as the intentions of the talker and the speaker’s age. Here, we report two experiments on age estimation by “naïve” listeners. The aim was to study how speech rate influences estimation of speaker age by comparing the speakers’ natural speech rate with increased or decreased speech rate. In Experiment 1, listeners were presented with audio samples of read speech from three different speaker age groups (young, middle aged, and old adults). They estimated the speakers as younger when speech rate was faster than normal and as older when speech rate was slower than normal. This speech rate effect was slightly greater in magnitude for older (60–65 years) speakers in comparison with younger (20–25 years) speakers, suggesting that speech rate may gain greater importance as a perceptual age cue with increased speaker age. This pattern was more pronounced in Experiment 2, in which listeners estimated age from spontaneous speech. Faster speech rate was associated with lower age estimates, but only for older and middle aged (40–45 years) speakers. Taken together, speakers of all age groups were estimated as older when speech rate decreased, except for the youngest speakers in Experiment 2. The absence of a linear speech rate effect in estimates of younger speakers, for spontaneous speech, implies that listeners use different age estimation strategies or cues (possibly vocabulary) depending on the age of the speaker and the spontaneity of the speech. Potential implications for forensic investigations and other applied domains are discussed. PMID:26236259

Forensic age estimation based on development of third molars: a staging technique for magnetic resonance imaging.

PubMed

De Tobel, J; Phlypo, I; Fieuws, S; Politis, C; Verstraete, K L; Thevissen, P W

2017-12-01

The development of third molars can be evaluated with medical imaging to estimate age in subadults. The appearance of third molars on magnetic resonance imaging (MRI) differs greatly from that on radiographs. Therefore a specific staging technique is necessary to classify third molar development on MRI and to apply it for age estimation. To develop a specific staging technique to register third molar development on MRI and to evaluate its performance for age estimation in subadults. Using 3T MRI in three planes, all third molars were evaluated in 309 healthy Caucasian participants from 14 to 26 years old. According to the appearance of the developing third molars on MRI, descriptive criteria and schematic representations were established to define a specific staging technique. Two observers, with different levels of experience, staged all third molars independently with the developed technique. Intra- and inter-observer agreement were calculated. The data were imported in a Bayesian model for age estimation as described by Fieuws et al. (2016). This approach adequately handles correlation between age indicators and missing age indicators. It was used to calculate a point estimate and a prediction interval of the estimated age. Observed age minus predicted age was calculated, reflecting the error of the estimate. One-hundred and sixty-six third molars were agenetic. Five percent (51/1096) of upper third molars and 7% (70/1044) of lower third molars were not assessable. Kappa for inter-observer agreement ranged from 0.76 to 0.80. For intra-observer agreement kappa ranged from 0.80 to 0.89. However, two stage differences between observers or between staging sessions occurred in up to 2.2% (20/899) of assessments, probably due to a learning effect. Using the Bayesian model for age estimation, a mean absolute error of 2.0 years in females and 1.7 years in males was obtained. Root mean squared error equalled 2.38 years and 2.06 years respectively. The performance to

Using age on clothes size label to estimate weight in emergency paediatric patients.

PubMed

Elgie, Laura D; Williams, Andrew R

2012-10-01

To study formulae that estimate children's weight using their actual age. To determine whether using the age on their clothes size label in these formulae can estimate weight when their actual age is unknown. The actual age and age on the clothes labels of 188 children were inserted into formulae that estimate children's weight. These estimates were compared with their actual weight. Bland-Altman plots calculated the precision and accuracy of each of these estimates. In all formulae, using age on the clothes sizes label provided a more precise estimate than the child's actual age. In emergencies where a child's age is unknown, use of the age on their clothes label in weight-estimating formulae yields acceptable weight estimates. Even in situations where a child's age is known, the age on their clothes label may provide a more accurate and precise weight estimate than the actual age.

Age estimation by pulp-to-tooth area ratio using cone-beam computed tomography: A preliminary analysis.

PubMed

Rai, Arpita; Acharya, Ashith B; Naikmasur, Venkatesh G

2016-01-01

Age estimation of living or deceased individuals is an important aspect of forensic sciences. Conventionally, pulp-to-tooth area ratio (PTR) measured from periapical radiographs have been utilized as a nondestructive method of age estimation. Cone-beam computed tomography (CBCT) is a new method to acquire three-dimensional images of the teeth in living individuals. The present study investigated age estimation based on PTR of the maxillary canines measured in three planes obtained from CBCT image data. Sixty subjects aged 20-85 years were included in the study. For each tooth, mid-sagittal, mid-coronal, and three axial sections-cementoenamel junction (CEJ), one-fourth root level from CEJ, and mid-root-were assessed. PTR was calculated using AutoCAD software after outlining the pulp and tooth. All statistical analyses were performed using an SPSS 17.0 software program. Linear regression analysis showed that only PTR in axial plane at CEJ had significant age correlation ( r = 0.32; P < 0.05). This is probably because of clearer demarcation of pulp and tooth outline at this level.

Improving the quality of parameter estimates obtained from slug tests

USGS Publications Warehouse

Butler, J.J.; McElwee, C.D.; Liu, W.

1996-01-01

The slug test is one of the most commonly used field methods for obtaining in situ estimates of hydraulic conductivity. Despite its prevalence, this method has received criticism from many quarters in the ground-water community. This criticism emphasizes the poor quality of the estimated parameters, a condition that is primarily a product of the somewhat casual approach that is often employed in slug tests. Recently, the Kansas Geological Survey (KGS) has pursued research directed it improving methods for the performance and analysis of slug tests. Based on extensive theoretical and field research, a series of guidelines have been proposed that should enable the quality of parameter estimates to be improved. The most significant of these guidelines are: (1) three or more slug tests should be performed at each well during a given test period; (2) two or more different initial displacements (Ho) should be used at each well during a test period; (3) the method used to initiate a test should enable the slug to be introduced in a near-instantaneous manner and should allow a good estimate of Ho to be obtained; (4) data-acquisition equipment that enables a large quantity of high quality data to be collected should be employed; (5) if an estimate of the storage parameter is needed, an observation well other than the test well should be employed; (6) the method chosen for analysis of the slug-test data should be appropriate for site conditions; (7) use of pre- and post-analysis plots should be an integral component of the analysis procedure, and (8) appropriate well construction parameters should be employed. Data from slug tests performed at a number of KGS field sites demonstrate the importance of these guidelines.

A Bayesian estimation of the helioseismic solar age

NASA Astrophysics Data System (ADS)

Bonanno, A.; Fröhlich, H.-E.

2015-08-01

Context. The helioseismic determination of the solar age has been a subject of several studies because it provides us with an independent estimation of the age of the solar system. Aims: We present the Bayesian estimates of the helioseismic age of the Sun, which are determined by means of calibrated solar models that employ different equations of state and nuclear reaction rates. Methods: We use 17 frequency separation ratios r02(n) = (νn,l = 0-νn-1,l = 2)/(νn,l = 1-νn-1,l = 1) from 8640 days of low-ℓBiSON frequencies and consider three likelihood functions that depend on the handling of the errors of these r02(n) ratios. Moreover, we employ the 2010 CODATA recommended values for Newton's constant, solar mass, and radius to calibrate a large grid of solar models spanning a conceivable range of solar ages. Results: It is shown that the most constrained posterior distribution of the solar age for models employing Irwin EOS with NACRE reaction rates leads to t⊙ = 4.587 ± 0.007 Gyr, while models employing the Irwin EOS and Adelberger, et al. (2011, Rev. Mod. Phys., 83, 195) reaction rate have t⊙ = 4.569 ± 0.006 Gyr. Implementing OPAL EOS in the solar models results in reduced evidence ratios (Bayes factors) and leads to an age that is not consistent with the meteoritic dating of the solar system. Conclusions: An estimate of the solar age that relies on an helioseismic age indicator such as r02(n) turns out to be essentially independent of the type of likelihood function. However, with respect to model selection, abandoning any information concerning the errors of the r02(n) ratios leads to inconclusive results, and this stresses the importance of evaluating the trustworthiness of error estimates.

Obtaining Reliable Estimates of Ambulatory Physical Activity in People with Parkinson's Disease.

PubMed

Paul, Serene S; Ellis, Terry D; Dibble, Leland E; Earhart, Gammon M; Ford, Matthew P; Foreman, K Bo; Cavanaugh, James T

2016-05-05

We determined the number of days required, and whether to include weekdays and/or weekends, to obtain reliable measures of ambulatory physical activity in people with Parkinson's disease (PD). Ninety-two persons with PD wore a step activity monitor for seven days. The number of days required to obtain a reliable estimate of daily activity was determined from the mean intraclass correlation (ICC2,1) for all possible combinations of 1-6 consecutive days of monitoring. Two days of monitoring were sufficient to obtain reliable daily activity estimates (ICC2,1 > 0.9). Amount (p = 0.03) but not intensity (p = 0.13) of ambulatory activity was greater on weekdays than weekends. Activity prescription based on amount rather than intensity may be more appropriate for people with PD.

Estimation of Gestational Age: Implications for Developmental Research.

ERIC Educational Resources Information Center

DiPietro, Janet A.; Allen, Marilee C.

1991-01-01

Reviews prenatal and postnatal methods of gestational age estimation and evaluates implementation of this information in research. Recommendations concerning the assignment of gestational age in the perinatal period and the use of age correction for preterm infants are offered. (Author/BC)

Characterization of rhenium compounds obtained by electrochemical synthesis after aging process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vargas-Uscategui, Alejandro, E-mail: avargasuscat@ing.uchile.cl; Mosquera, Edgar; López-Encarnación, Juan M.

2014-12-15

The proper identification of the molecular nature of the aged rhenium compound obtained by means of electrodeposition from an alkaline aqueous electrolyte was determined. Chemical, structural and vibrational experimental characterization of the aged Re compound showed agreement with quantum-computations, thereby allowing the unambiguous identification of the Re compound as H(ReO{sub 4})H{sub 2}O. - Graphical abstract: Rhenium oxides were electrodeposited on a copper surface and after environmental aging was formed the H(ReO{sub 4})H{sub 2}O compound. The characterization of the synthesized material was made through the comparison of experimental evidence with quantum mechanical computations carried out by means of density functional theorymore » (DFT). - Highlights: • Aged rhenium compound obtained by means of electrodeposition was studied. • The study was made by combining experimental and DFT-computational information. • The aged electrodeposited material is consistent with the H(ReO{sub 4})H{sub 2}O compound.« less

Comparative study of age estimation using dentinal translucency by digital and conventional methods

PubMed Central

Bommannavar, Sushma; Kulkarni, Meena

2015-01-01

Introduction: Estimating age using the dentition plays a significant role in identification of the individual in forensic cases. Teeth are one of the most durable and strongest structures in the human body. The morphology and arrangement of teeth vary from person-to-person and is unique to an individual as are the fingerprints. Therefore, the use of dentition is the method of choice in the identification of the unknown. Root dentin translucency is considered to be one of the best parameters for dental age estimation. Traditionally, root dentin translucency was measured using calipers. Recently, the use of custom built software programs have been proposed for the same. Objectives: The present study describes a method to measure root dentin translucency on sectioned teeth using a custom built software program Adobe Photoshop 7.0 version (Adobe system Inc, Mountain View California). Materials and Methods: A total of 50 single rooted teeth were sectioned longitudinally to derive a 0.25 mm uniform thickness and the root dentin translucency was measured using digital and caliper methods and compared. The Gustafson's morphohistologic approach is used in this study. Results: Correlation coefficients of translucency measurements to age were statistically significant for both the methods (P < 0.125) and linear regression equations derived from both methods revealed better ability of the digital method to assess age. Conclusion: The custom built software program used in the present study is commercially available and widely used image editing software. Furthermore, this method is easy to use and less time consuming. The measurements obtained using this method are more precise and thus help in more accurate age estimation. Considering these benefits, the present study recommends the use of digital method to assess translucency for age estimation. PMID:25709325

Age estimation in 25-45 yrs. old females by physical and radiological methods

PubMed Central

Kasat, Vikrant; Karjodkar, FR; Vaz, Walter

2010-01-01

Aim: The purpose of this study was to estimate the age in living females in the later years (25 to 45 years) from general physical features and radiographic changes in the sternum and the mandible. Materials and Methods: A cross-sectional study was conducted on 64 females (32 subjects in each study and control group). All the subjects were physically examined for graying of scalp, body, pubic hair, and for wrinkling of skin of the forehead, temporal region, and below the eyes. A right lateral view of the chest was taken to determine fusion of the components of the sternum. Combined Hair Score, Combined Skin Score, and Combined Bone Fusion Score were calculated. An orthopantomogram of each patient was traced for lower jaw, mandibular canal and teeth, and D1, D2, A values were calculated. SPSS Software Version 10.1 was used for the execution of the regression command on the 32 cases of the control group, whose ages were known. Results: Combined skin score, mandible right D2, mandible right angle, and mandible left angle turned out significant in the prediction of age. Using the regression equation obtained, the age of the 32 subjects in the study group was estimated. In 9.3% of cases, the predicted ages exactly matched the actual ages. A variation of 1–4 years was seen in 75% of the cases. A variation of 6–7 years was seen in 15.6% of the cases. Conclusion: This study succeeded in most instances in predicting the ages of the study group and in arriving at a formula for age estimation between the ages of 25 and 45 years without using any invasive, costly, time - consuming, or troublesome method. PMID:21731347

Estimating the brain pathological age of Alzheimer’s disease patients from MR image data based on the separability distance criterion

NASA Astrophysics Data System (ADS)

Li, Yongming; Li, Fan; Wang, Pin; Zhu, Xueru; Liu, Shujun; Qiu, Mingguo; Zhang, Jingna; Zeng, Xiaoping

2016-10-01

Traditional age estimation methods are based on the same idea that uses the real age as the training label. However, these methods ignore that there is a deviation between the real age and the brain age due to accelerated brain aging. This paper considers this deviation and searches for it by maximizing the separability distance value rather than by minimizing the difference between the estimated brain age and the real age. Firstly, set the search range of the deviation as the deviation candidates according to prior knowledge. Secondly, use the support vector regression (SVR) as the age estimation model to minimize the difference between the estimated age and the real age plus deviation rather than the real age itself. Thirdly, design the fitness function based on the separability distance criterion. Fourthly, conduct age estimation on the validation dataset using the trained age estimation model, put the estimated age into the fitness function, and obtain the fitness value of the deviation candidate. Fifthly, repeat the iteration until all the deviation candidates are involved and get the optimal deviation with maximum fitness values. The real age plus the optimal deviation is taken as the brain pathological age. The experimental results showed that the separability was apparently improved. For normal control-Alzheimer’s disease (NC-AD), normal control-mild cognition impairment (NC-MCI), and MCI-AD, the average improvements were 0.178 (35.11%), 0.033 (14.47%), and 0.017 (39.53%), respectively. For NC-MCI-AD, the average improvement was 0.2287 (64.22%). The estimated brain pathological age could be not only more helpful to the classification of AD but also more precisely reflect accelerated brain aging. In conclusion, this paper offers a new method for brain age estimation that can distinguish different states of AD and can better reflect the extent of accelerated aging.

The Estimation of Gestational Age at Birth in Database Studies.

PubMed

Eberg, Maria; Platt, Robert W; Filion, Kristian B

2017-11-01

Studies on the safety of prenatal medication use require valid estimation of the pregnancy duration. However, gestational age is often incompletely recorded in administrative and clinical databases. Our objective was to compare different approaches to estimating the pregnancy duration. Using data from the Clinical Practice Research Datalink and Hospital Episode Statistics, we examined the following four approaches to estimating missing gestational age: (1) generalized estimating equations for longitudinal data; (2) multiple imputation; (3) estimation based on fetal birth weight and sex; and (4) conventional approaches that assigned a fixed value (39 weeks for all or 39 weeks for full term and 35 weeks for preterm). The gestational age recorded in Hospital Episode Statistics was considered the gold standard. We conducted a simulation study comparing the described approaches in terms of estimated bias and mean square error. A total of 25,929 infants from 22,774 mothers were included in our "gold standard" cohort. The smallest average absolute bias was observed for the generalized estimating equation that included birth weight, while the largest absolute bias occurred when assigning 39-week gestation to all those with missing values. The smallest mean square errors were detected with generalized estimating equations while multiple imputation had the highest mean square errors. The use of generalized estimating equations resulted in the most accurate estimation of missing gestational age when birth weight information was available. In the absence of birth weight, assignment of fixed gestational age based on term/preterm status may be the optimal approach.

Predictive Demi-Span Equations for Estimation of Stature in Aged Mexican Americans.

PubMed

Siordia, C; Panas, L J; Markides, K

2012-01-01

To develop demi-span height predictive equations for older Mexican Americans. Cross-sectional study. Data files housed by the Sociomedical Division in the department of Community Health and Preventive Medicine at the University of Texas Medical Branch in Galveston, Texas. 1,078 (700 females, 378 males) Southwest U.S.A. community-dwelling older Mexican Americans, aged 80-102 years. Demi-span, height, weight, BMI, demi-span equivalent height (DSEH), DSEH derived BMI (DS-BMI). Bland and Altman agreement analysis on: height and DSEH; BMI and DS-BMI. Paired t-test comparing derived and actual measures by single-age units and sex. DSEH with Bassey equations (DSEHBassey) are significantly different than actual measures. DSEHBassey derived BMIs (DSBasseyBMIs) are significantly different than BMIs computed from actual measures. DSEH with Mexican equations (DSEHMexican) are not significantly different than real measures. DSEHMexican derived BMIs (DSMexicanBMIs) are not significantly different than real measures. These findings provide evidence that both DSEHBassey and DSBasseyBMIs estimates are significantly different from measured height and BMI. Both DSEHMexican and DSMexicanBMIs estimates are shown to produce similar height and BMI estimates to those obtained from real measures. .

Simplified estimation of age-specific reference intervals for skewed data.

PubMed

Wright, E M; Royston, P

1997-12-30

Age-specific reference intervals are commonly used in medical screening and clinical practice, where interest lies in the detection of extreme values. Many different statistical approaches have been published on this topic. The advantages of a parametric method are that they necessarily produce smooth centile curves, the entire density is estimated and an explicit formula is available for the centiles. The method proposed here is a simplified version of a recent approach proposed by Royston and Wright. Basic transformations of the data and multiple regression techniques are combined to model the mean, standard deviation and skewness. Using these simple tools, which are implemented in almost all statistical computer packages, age-specific reference intervals may be obtained. The scope of the method is illustrated by fitting models to several real data sets and assessing each model using goodness-of-fit techniques.

Estimating lifetime and age-conditional probabilities of developing cancer.

PubMed

Wun, L M; Merrill, R M; Feuer, E J

1998-01-01

Lifetime and age-conditional risk estimates of developing cancer provide a useful summary to the public of the current cancer risk and how this risk compares with earlier periods and among select subgroups of society. These reported estimates, commonly quoted in the popular press, have the potential to promote early detection efforts, to increase cancer awareness, and to serve as an aid in study planning. However, they can also be easily misunderstood and frightening to the general public. The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute and the American Cancer Society have recently begun including in annual reports lifetime and age-conditional risk estimates of developing cancer. These risk estimates are based on incidence rates that reflect new cases of the cancer in a population free of the cancer. To compute these estimates involves a cancer prevalence adjustment that is computed cross-sectionally from current incidence and mortality data derived within a multiple decrement life table. This paper presents a detailed description of the methodology for deriving lifetime and age-conditional risk estimates of developing cancer. In addition, an extension is made which, using a triple decrement life table, adjusts for a surgical procedure that removes individuals from the risk of developing a given cancer. Two important results which provide insights into the basic methodology are included in the discussion. First, the lifetime risk estimate does not depend on the cancer prevalence adjustment, although this is not the case for age-conditional risk estimates. Second, the lifetime risk estimate is always smaller when it is corrected for a surgical procedure that takes people out of the risk pool to develop the cancer. The methodology is applied to corpus and uterus NOS cancers, with a correction made for hysterectomy prevalence. The interpretation and limitations of risk estimates are also discussed.

The Prevalence of Age-Related Eye Diseases and Visual Impairment in Aging: Current Estimates

PubMed Central

Klein, Ronald; Klein, Barbara E. K.

2013-01-01

Purpose. To examine prevalence of five age-related eye conditions (age-related cataract, AMD, open-angle glaucoma, diabetic retinopathy [DR], and visual impairment) in the United States. Methods. Review of published scientific articles and unpublished research findings. Results. Cataract, AMD, open-angle glaucoma, DR, and visual impairment prevalences are high in four different studies of these conditions, especially in people over 75 years of age. There are disparities among racial/ethnic groups with higher age-specific prevalence of DR, open-angle glaucoma, and visual impairment in Hispanics and blacks compared with whites, higher prevalence of age-related cataract in whites compared with blacks, and higher prevalence of late AMD in whites compared with Hispanics and blacks. The estimates are based on old data and do not reflect recent changes in the distribution of age and race/ethnicity in the United States population. There are no epidemiologic estimates of prevalence for many visually-impairing conditions. Conclusions. Ongoing prevalence surveys designed to provide reliable estimates of visual impairment, AMD, age-related cataract, open-angle glaucoma, and DR are needed. It is important to collect objective data on these and other conditions that affect vision and quality of life in order to plan for health care needs and identify areas for further research. PMID:24335069

Comparison of age estimation between 15-25 years using a modified form of Demirjian’s ten stage method and two teeth regression formula

NASA Astrophysics Data System (ADS)

Amiroh; Priaminiarti, M.; Syahraini, S. I.

2017-08-01

Age estimation of individuals, both dead and living, is important for victim identification and legal certainty. The Demirjian method uses the third molar for age estimation of individuals above 15 years old. The aim is to compare age estimation between 15-25 years using two Demirjian methods. Development stage of third molars in panoramic radiographs of 50 male and female samples were assessed by two observers using Demirjian’s ten stages and two teeth regression formula. Reliability was calculated using Cohen’s kappa coefficient and the significance of the observations was obtained from Wilcoxon tests. Deviations of age estimation were calculated using various methods. The deviation of age estimation with the two teeth regression formula was ±1.090 years; with ten stages, it was ±1.191 years. The deviation of age estimation using the two teeth regression formula was less than with the ten stages method. The age estimations using the two teeth regression formula or the ten stages method are significantly different until the age of 25, but they can be applied up to the age of 22.

Racemization of aspartic acid in root dentin as a tool for age estimation in a Kuwaiti population.

PubMed

Elfawal, Mohamed Amin; Alqattan, Sahib Issa; Ghallab, Noha Ayman

2015-01-01

Estimation of age is one of the most significant tasks in forensic practice. Amino acid racemization is considered one of the most reliable and accurate methods of age estimation and aspartic acid shows a high racemization reaction rate. The present study has investigated the application of aspartic acid racemization in age estimation in a Kuwaiti population using root dentin from a total of 89 upper first premolar teeth. The D/L ratio of aspartic acid was obtained by HPLC technique in a test group of 50 subjects and a linear regression line was established between aspartic acid racemization and age. The correlation coefficient (r) was 0.97, and the standard error of estimation was ±1.26 years. The racemization age "t" of each subject was calculated by applying the following formula: ln [(1 + D/L)/(1 - D/L)] = 0.003181 t + (-0.01591). When the proposed formula "estimated age t = ln [(1 + D/L)/(1 - D/L)] + 0.01591/0.003181" was applied to a validation group of 39 subjects, the range of error was less than one year in 82.1% of the cases and the standard error of estimation was ±1.12. The current work has established a reasonably significant correlation of the D-/L-aspartic acid ratio with age, and proposed an apparently reliable formula for calculating the age in Kuwaiti populations through aspartic acid racemization. Further research is required to find out whether similar findings are applicable to other ethnic populations. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Age estimation by pulp-to-tooth area ratio using cone-beam computed tomography: A preliminary analysis

PubMed Central

Rai, Arpita; Acharya, Ashith B.; Naikmasur, Venkatesh G.

2016-01-01

Background: Age estimation of living or deceased individuals is an important aspect of forensic sciences. Conventionally, pulp-to-tooth area ratio (PTR) measured from periapical radiographs have been utilized as a nondestructive method of age estimation. Cone-beam computed tomography (CBCT) is a new method to acquire three-dimensional images of the teeth in living individuals. Aims: The present study investigated age estimation based on PTR of the maxillary canines measured in three planes obtained from CBCT image data. Settings and Design: Sixty subjects aged 20–85 years were included in the study. Materials and Methods: For each tooth, mid-sagittal, mid-coronal, and three axial sections—cementoenamel junction (CEJ), one-fourth root level from CEJ, and mid-root—were assessed. PTR was calculated using AutoCAD software after outlining the pulp and tooth. Statistical Analysis Used: All statistical analyses were performed using an SPSS 17.0 software program. Results and Conclusions: Linear regression analysis showed that only PTR in axial plane at CEJ had significant age correlation (r = 0.32; P < 0.05). This is probably because of clearer demarcation of pulp and tooth outline at this level. PMID:28123269

Estimation of age- and stage-specific Catalan breast cancer survival functions using US and Catalan survival data

PubMed Central

2009-01-01

Background During the last part of the 1990s the chance of surviving breast cancer increased. Changes in survival functions reflect a mixture of effects. Both, the introduction of adjuvant treatments and early screening with mammography played a role in the decline in mortality. Evaluating the contribution of these interventions using mathematical models requires survival functions before and after their introduction. Furthermore, required survival functions may be different by age groups and are related to disease stage at diagnosis. Sometimes detailed information is not available, as was the case for the region of Catalonia (Spain). Then one may derive the functions using information from other geographical areas. This work presents the methodology used to estimate age- and stage-specific Catalan breast cancer survival functions from scarce Catalan survival data by adapting the age- and stage-specific US functions. Methods Cubic splines were used to smooth data and obtain continuous hazard rate functions. After, we fitted a Poisson model to derive hazard ratios. The model included time as a covariate. Then the hazard ratios were applied to US survival functions detailed by age and stage to obtain Catalan estimations. Results We started estimating the hazard ratios for Catalonia versus the USA before and after the introduction of screening. The hazard ratios were then multiplied by the age- and stage-specific breast cancer hazard rates from the USA to obtain the Catalan hazard rates. We also compared breast cancer survival in Catalonia and the USA in two time periods, before cancer control interventions (USA 1975–79, Catalonia 1980–89) and after (USA and Catalonia 1990–2001). Survival in Catalonia in the 1980–89 period was worse than in the USA during 1975–79, but the differences disappeared in 1990–2001. Conclusion Our results suggest that access to better treatments and quality of care contributed to large improvements in survival in Catalonia. On

Targeted estimation of nuisance parameters to obtain valid statistical inference.

PubMed

van der Laan, Mark J

2014-01-01

In order to obtain concrete results, we focus on estimation of the treatment specific mean, controlling for all measured baseline covariates, based on observing independent and identically distributed copies of a random variable consisting of baseline covariates, a subsequently assigned binary treatment, and a final outcome. The statistical model only assumes possible restrictions on the conditional distribution of treatment, given the covariates, the so-called propensity score. Estimators of the treatment specific mean involve estimation of the propensity score and/or estimation of the conditional mean of the outcome, given the treatment and covariates. In order to make these estimators asymptotically unbiased at any data distribution in the statistical model, it is essential to use data-adaptive estimators of these nuisance parameters such as ensemble learning, and specifically super-learning. Because such estimators involve optimal trade-off of bias and variance w.r.t. the infinite dimensional nuisance parameter itself, they result in a sub-optimal bias/variance trade-off for the resulting real-valued estimator of the estimand. We demonstrate that additional targeting of the estimators of these nuisance parameters guarantees that this bias for the estimand is second order and thereby allows us to prove theorems that establish asymptotic linearity of the estimator of the treatment specific mean under regularity conditions. These insights result in novel targeted minimum loss-based estimators (TMLEs) that use ensemble learning with additional targeted bias reduction to construct estimators of the nuisance parameters. In particular, we construct collaborative TMLEs (C-TMLEs) with known influence curve allowing for statistical inference, even though these C-TMLEs involve variable selection for the propensity score based on a criterion that measures how effective the resulting fit of the propensity score is in removing bias for the estimand. As a particular special

Accuracy and precision of estimating age of gray wolves by tooth wear

USGS Publications Warehouse

Gipson, P.S.; Ballard, W.B.; Nowak, R.M.; Mech, L.D.

2000-01-01

We evaluated the accuracy and precision of tooth wear for aging gray wolves (Canis lupus) from Alaska, Minnesota, and Ontario based on 47 known-age or known-minimum-age skulls. Estimates of age using tooth wear and a commercial cementum annuli-aging service were useful for wolves up to 14 years old. The precision of estimates from cementum annuli was greater than estimates from tooth wear, but tooth wear estimates are more applicable in the field. We tended to overestimate age by 1-2 years and occasionally by 3 or 4 years. The commercial service aged young wolves with cementum annuli to within ?? 1 year of actual age, but under estimated ages of wolves ???9 years old by 1-3 years. No differences were detected in tooth wear patterns for wild wolves from Alaska, Minnesota, and Ontario, nor between captive and wild wolves. Tooth wear was not appropriate for aging wolves with an underbite that prevented normal wear or severely broken and missing teeth.

Applications of physiological bases of ageing to forensic sciences. Estimation of age-at-death.

PubMed

C Zapico, Sara; Ubelaker, Douglas H

2013-03-01

Age-at-death estimation is one of the main challenges in forensic sciences since it contributes to the identification of individuals. There are many anthropological techniques to estimate the age at death in children and adults. However, in adults this methodology is less accurate and requires population specific references. For that reason, new methodologies have been developed. Biochemical methods are based on the natural process of ageing, which induces different biochemical changes that lead to alterations in cells and tissues. In this review, we describe different attempts to estimate the age in adults based on these changes. Chemical approaches imply modifications in molecules or accumulation of some products. Molecular biology approaches analyze the modifications in DNA and chromosomes. Although the most accurate technique appears to be aspartic acid racemization, it is important to take into account the other techniques because the forensic context and the human remains available will determine the possibility to apply one or another methodology. Copyright © 2013 Elsevier B.V. All rights reserved.

Dental cementum in age estimation: a polarized light and stereomicroscopic study.

PubMed

Kasetty, Sowmya; Rammanohar, M; Raju Ragavendra, T

2010-05-01

Dental hard tissues are good candidates for age estimation as they are less destructive and procedures to determine age can be easily performed. Although cementum annulations and cementum thickness are important parameters in this regard, they are seldom used. This study was undertaken to review the methods, difficulties in execution of techniques, and accuracy of cementum thickness and annulations in estimating the age. Unstained and stained ground sections of tooth were used to measure cemental thickness and count cemental annulations based on which age was estimated and was compared with known age. Although there was positive relation between cemental thickness and annulations with age, only in 1-1.5% of cases, age could be predicted with accuracy.

Re-evaluating neonatal-age models for ungulates: Does model choice affect survival estimates?

USGS Publications Warehouse

Grovenburg, Troy W.; Monteith, Kevin L.; Jacques, Christopher N.; Klaver, Robert W.; DePerno, Christopher S.; Brinkman, Todd J.; Monteith, Kyle B.; Gilbert, Sophie L.; Smith, Joshua B.; Bleich, Vernon C.; Swanson, Christopher C.; Jenks, Jonathan A.

2014-01-01

New-hoof growth is regarded as the most reliable metric for predicting age of newborn ungulates, but variation in estimated age among hoof-growth equations that have been developed may affect estimates of survival in staggered-entry models. We used known-age newborns to evaluate variation in age estimates among existing hoof-growth equations and to determine the consequences of that variation on survival estimates. During 2001–2009, we captured and radiocollared 174 newborn (≤24-hrs old) ungulates: 76 white-tailed deer (Odocoileus virginianus) in Minnesota and South Dakota, 61 mule deer (O. hemionus) in California, and 37 pronghorn (Antilocapra americana) in South Dakota. Estimated age of known-age newborns differed among hoof-growth models and varied by >15 days for white-tailed deer, >20 days for mule deer, and >10 days for pronghorn. Accuracy (i.e., the proportion of neonates assigned to the correct age) in aging newborns using published equations ranged from 0.0% to 39.4% in white-tailed deer, 0.0% to 3.3% in mule deer, and was 0.0% for pronghorns. Results of survival modeling indicated that variability in estimates of age-at-capture affected short-term estimates of survival (i.e., 30 days) for white-tailed deer and mule deer, and survival estimates over a longer time frame (i.e., 120 days) for mule deer. Conversely, survival estimates for pronghorn were not affected by estimates of age. Our analyses indicate that modeling survival in daily intervals is too fine a temporal scale when age-at-capture is unknown given the potential inaccuracies among equations used to estimate age of neonates. Instead, weekly survival intervals are more appropriate because most models accurately predicted ages within 1 week of the known age. Variation among results of neonatal-age models on short- and long-term estimates of survival for known-age young emphasizes the importance of selecting an appropriate hoof-growth equation and appropriately defining intervals (i.e., weekly

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

PubMed

Lottering, Nicolene; MacGregor, Donna M; Alston, Clair L; Watson, Debbie; Gregory, Laura S

2016-01-01

Contemporary, population-specific ossification timings of the cranium are lacking in current literature due to challenges in obtaining large repositories of documented subadult material, forcing Australian practitioners to rely on North American, arguably antiquated reference standards for age estimation. This study assessed the temporal pattern of ossification of the cranium and provides recalibrated probabilistic information for age estimation of modern Australian children. Fusion status of the occipital and frontal bones, atlas, and axis was scored using a modified two- to four-tier system from cranial/cervical DICOM datasets of 585 children aged birth to 10 years. Transition analysis was applied to elucidate maximum-likelihood estimates between consecutive fusion stages, in conjunction with Bayesian statistics to calculate credible intervals for age estimation. Results demonstrate significant sex differences in skeletal maturation (p < 0.05) and earlier timings in comparison with major literary sources, underscoring the requisite of updated standards for age estimation of modern individuals. © 2015 American Academy of Forensic Sciences.

Age Estimation in Forensic Sciences

PubMed Central

Alkass, Kanar; Buchholz, Bruce A.; Ohtani, Susumu; Yamamoto, Toshiharu; Druid, Henrik; Spalding, Kirsty L.

2010-01-01

Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster because the age at death, birth date, and year of death as well as gender can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization, has shown reproducible and more precise results. In this study, we analyzed teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that aboveground testing of nuclear weapons during the cold war (1955–1963) caused an extreme increase in global levels of carbon-14 (14C), which has been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel, and 10 of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2 = 0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 1.0 ± 0.6 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 ± 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification. PMID:19965905

Estimating Building Age with 3d GIS

NASA Astrophysics Data System (ADS)

Biljecki, F.; Sindram, M.

2017-10-01

Building datasets (e.g. footprints in OpenStreetMap and 3D city models) are becoming increasingly available worldwide. However, the thematic (attribute) aspect is not always given attention, as many of such datasets are lacking in completeness of attributes. A prominent attribute of buildings is the year of construction, which is useful for some applications, but its availability may be scarce. This paper explores the potential of estimating the year of construction (or age) of buildings from other attributes using random forest regression. The developed method has a two-fold benefit: enriching datasets and quality control (verification of existing attributes). Experiments are carried out on a semantically rich LOD1 dataset of Rotterdam in the Netherlands using 9 attributes. The results are mixed: the accuracy in the estimation of building age depends on the available information used in the regression model. In the best scenario we have achieved predictions with an RMSE of 11 years, but in more realistic situations with limited knowledge about buildings the error is much larger (RMSE = 26 years). Hence the main conclusion of the paper is that inferring building age with 3D city models is possible to a certain extent because it reveals the approximate period of construction, but precise estimations remain a difficult task.

Evaluation of third molar development in the estimation of chronological age.

PubMed

Soares, Caio Belém Rodrigues Barros; Figueiroa, José Natal; Dantas, Renata Moura Xavier; Kurita, Lúcio Mitsuo; Pontual, Andréa dos Anjos; Ramos-Perez, Flávia Maria de Moraes; Perez, Danyel Elias da Cruz; Pontual, Maria Luiza dos Anjos

2015-09-01

The purpose of this study was to evaluate the correlation between chronological age and the degree of third molar mineralization by Demirjian's developmental stages (Demirjian et al., 1973) using panoramic radiography. From a total of 11.396 digital panoramic radiographs of patients from three oral radiology private clinics from the northeast region of Brazil, obtained from January to June 2009, 2097 radiographic images from patients aged between 6 and 22 years were selected. The images were analyzed individually by two obsevers using a 21-inch computer screen and Windows Picture and Fax Viewer. Reliability was achieved by intra- and interobserver evaluation, using the Kappa test. Chronological age, calcification stage, gender and third molar were interrelated using a multiple linear regression model, considering age as a response variable. There was reliability with Demirjian et al.'s developmental stage assesment, displaying a significant relationship between mineralization stages and patients' age (P<0.05). There was no significant difference between the average age and the calcification stage taking gender and localization of the third molar into consideration. It is possible to estimate chronological age based on Demirjian's stage of a third molar, regardless of gender and location. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Radiologic assessment of third molar tooth and spheno-occipital synchondrosis for age estimation: a multiple regression analysis study.

PubMed

Demirturk Kocasarac, Husniye; Sinanoglu, Alper; Noujeim, Marcel; Helvacioglu Yigit, Dilek; Baydemir, Canan

2016-05-01

For forensic age estimation, radiographic assessment of third molar mineralization is important between 14 and 21 years which coincides with the legal age in most countries. The spheno-occipital synchondrosis (SOS) is an important growth site during development, and its use for age estimation is beneficial when combined with other markers. In this study, we aimed to develop a regression model to estimate and narrow the age range based on the radiologic assessment of third molar and SOS in a Turkish subpopulation. Panoramic radiographs and cone beam CT scans of 349 subjects (182 males, 167 females) with age between 8 and 25 were evaluated. Four-stage system was used to evaluate the fusion degree of SOS, and Demirjian's eight stages of development for calcification for third molars. The Pearson correlation indicated a strong positive relationship between age and third molar calcification for both sexes (r = 0.850 for females, r = 0.839 for males, P < 0.001) and also between age and SOS fusion for females (r = 0.814), but a moderate relationship was found for males (r = 0.599), P < 0.001). Based on the results obtained, an age determination formula using these scores was established.

Age estimation using tooth cementum annulation.

PubMed

Wittwer-Backofen, Ursula

2012-01-01

In Forensic Anthropology age diagnosis of unidentified bodies significantly helps in the identification process. Among the set of established aging methods in anthropology tooth cementum annulation (TCA) is increasingly used due to its narrow error range which can reach 5 years of age in adult individuals at best. The rhythm of cementum appositions of seasonally different density provides a principal mechanism on which TCA is based. Using histological preparation techniques for hard tissues, transversal tooth root sections are produced which can be analyzed in transmitted light microscopy. Even though no standard TCA preparation protocol exists, several methodological validation studies recommend specific treatments depending on individual conditions of the teeth. Individual age is estimated by adding mean tooth eruption age to the number of microscopically detected dark layers which are separated by bright layers and stand for 1 year of age each. To assure a high reliability of the method, TCA age diagnosis has to be based on several teeth of one individual if possible and needs to be supported by different techniques in forensic cases.

DNA methylation markers in combination with skeletal and dental ages to improve age estimation in children.

PubMed

Shi, Lei; Jiang, Fan; Ouyang, Fengxiu; Zhang, Jun; Wang, Zhimin; Shen, Xiaoming

2018-03-01

Age estimation is critical in forensic science, in competitive sports and games and in other age-related fields, but the current methods are suboptimal. The combination of age-associated DNA methylation markers with skeletal age (SA) and dental age (DA) may improve the accuracy and precision of age estimation, but no study has examined this topic. In the current study, we measured SA (GP, TW3-RUS, and TW3-Carpal methods) and DA (Demirjian and Willems methods) by X-ray examination in 124 Chinese children (78 boys and 46 girls) aged 6-15 years. To identify age-associated CpG sites, we analyzed methylome-wide DNA methylation profiling by using the Illumina HumanMethylation450 BeadChip system in 48 randomly selected children. Five CpG sites were identified as associated with chronologic age (CA), with an absolute value of Pearson's correlation coefficient (r)>0.5 (p<0.01) and a false discovery rate<0.01. The validation of age-associated CpG sites was performed using droplet digital PCR techniques in all 124 children. After validation, four CpG sites for boys and five CpG sites for girls were further adopted to build the age estimation model with SA and DA using multivariate linear stepwise regressions. These CpG sites were located at 4 known genes: DDO, PRPH2, DHX8, and ITGA2B and at one unknown gene with the Illumina ID number of 22398226. The accuracy of age estimation methods was compared according to the mean absolute error (MAE) and root mean square error (RMSE). The best single measure for SA was the TW3-RUS method (MAE=0.69years, RMSE=0.95years) in boys, and the GP method (MAE=0.74years, RMSE=0.94years) in girls. For DA, the Willems method was the best single measure for both boys (MAE=0.63years, RMSE=0.78years) and girls (MAE=0.54years, RMSE=0.68years). The models that incorporated SA and DA with the methylation levels of age-associated CpG sites provided the highest accuracy of age estimation in both boys (MAE=0.47years, R 2 =0.886) and girls (MAE=0.33years, R

Forensic age estimation on digital X-ray images: Medial epiphyses of the clavicle and first rib ossification in relation to chronological age.

PubMed

Garamendi, Pedro M; Landa, Maria I; Botella, Miguel C; Alemán, Inmaculada

2011-01-01

In recent years, there has been a renewed interest in forensic sciences about forensic age estimation in living subjects by means of radiological methods. This research was conducted on digital thorax X-rays to test the usefulness of some radiological changes in the clavicle and first rib. The sample consisted in a total of 123 subjects of Spanish origin (61 men and 62 women; age range: 5-75 years). From all subjects, a thorax posterior-anterior radiograph was obtained in digital format. Scoring for fusion of medial epiphyses of the clavicle was carried out by Schmeling's system and ossification of the costal cartilage of the first rib by Michelson's system. Degree of ossification and epiphyseal fusion were analyzed in relation with known age and sex of these subjects. The results give a minimum age of >20 years for full fusion of the medial epiphysis of the clavicle (Stages 4 and 5). Concerning the first rib, all subjects with the final Stage 3 of ossification were above 25 years of age. These results suggest that the first rib ossification might become an additional method to the ones so far recommended for forensic age estimation in subjects around 21. New research would be desirable to confirm this suggestion. © 2010 American Academy of Forensic Sciences.

New thermoluminescence age estimates for the Nyos maar eruption (Cameroon Volcanic Line)

PubMed Central

Tchouankoue, Jean Pierre; Nkouamen Nemzoue, Peguy Noel; Ayaba, Félicité; Nformidah-Ndah, Siggy Signe; Nformi Chifu, Emmanuel

2017-01-01

Nyos maar is located in the Cameroon Volcanic Line and generates a multitude of primary and secondary hazards to the local population. For risk assessment and hazard mitigation, the age of the Nyos maar eruption provides some vital information. Since previous dating efforts using a range of techniques resulted in vastly varying eruption ages, we applied thermoluminescence (TL) methods to obtain independent and direct chronological constraints for the time of maar formation. Target minerals were granitic quartz clasts contained in pyroclastic surge deposits. Thermoluminescence plateau results prove that heat and/or pressure during the phreatomagmatic eruption was sufficient to reset the inherited luminescence signal of granitic bedrock quartz. Parallel application of three TL measurement protocols to one of the two samples gave consistent equivalent doses for the quartz ultra-violet emission. Despite the robustness of our dose estimates, the assessment of the dose rate was accompanied by methodological challenges, such as estimation of the original size distribution of quartz grains in the pyroclastic deposits. Considering results from additional laboratory analyses to constrain these uncertainties, we calculate an average maximum TL age of 12.3 ± 1.5 ka for the Nyos maar eruption. Based on these new data, a more solid risk assessment can be envisaged. PMID:28558057

New thermoluminescence age estimates for the Nyos maar eruption (Cameroon Volcanic Line).

PubMed

Schmidt, Christoph; Tchouankoue, Jean Pierre; Nkouamen Nemzoue, Peguy Noel; Ayaba, Félicité; Nformidah-Ndah, Siggy Signe; Nformi Chifu, Emmanuel

2017-01-01

Nyos maar is located in the Cameroon Volcanic Line and generates a multitude of primary and secondary hazards to the local population. For risk assessment and hazard mitigation, the age of the Nyos maar eruption provides some vital information. Since previous dating efforts using a range of techniques resulted in vastly varying eruption ages, we applied thermoluminescence (TL) methods to obtain independent and direct chronological constraints for the time of maar formation. Target minerals were granitic quartz clasts contained in pyroclastic surge deposits. Thermoluminescence plateau results prove that heat and/or pressure during the phreatomagmatic eruption was sufficient to reset the inherited luminescence signal of granitic bedrock quartz. Parallel application of three TL measurement protocols to one of the two samples gave consistent equivalent doses for the quartz ultra-violet emission. Despite the robustness of our dose estimates, the assessment of the dose rate was accompanied by methodological challenges, such as estimation of the original size distribution of quartz grains in the pyroclastic deposits. Considering results from additional laboratory analyses to constrain these uncertainties, we calculate an average maximum TL age of 12.3 ± 1.5 ka for the Nyos maar eruption. Based on these new data, a more solid risk assessment can be envisaged.

NMR permeability estimators in 'chalk' carbonate rocks obtained under different relaxation times and MICP size scalings

NASA Astrophysics Data System (ADS)

Rios, Edmilson Helton; Figueiredo, Irineu; Moss, Adam Keith; Pritchard, Timothy Neil; Glassborow, Brent Anthony; Guedes Domingues, Ana Beatriz; Bagueira de Vasconcellos Azeredo, Rodrigo

2016-07-01

The effect of the selection of different nuclear magnetic resonance (NMR) relaxation times for permeability estimation is investigated for a set of fully brine-saturated rocks acquired from Cretaceous carbonate reservoirs in the North Sea and Middle East. Estimators that are obtained from the relaxation times based on the Pythagorean means are compared with estimators that are obtained from the relaxation times based on the concept of a cumulative saturation cut-off. Select portions of the longitudinal (T1) and transverse (T2) relaxation-time distributions are systematically evaluated by applying various cut-offs, analogous to the Winland-Pittman approach for mercury injection capillary pressure (MICP) curves. Finally, different approaches to matching the NMR and MICP distributions using different mean-based scaling factors are validated based on the performance of the related size-scaled estimators. The good results that were obtained demonstrate possible alternatives to the commonly adopted logarithmic mean estimator and reinforce the importance of NMR-MICP integration to improving carbonate permeability estimates.

Comparison of gyrochronological and isochronal age estimates for transiting exoplanet host stars

NASA Astrophysics Data System (ADS)

Maxted, P. F. L.; Serenelli, A. M.; Southworth, J.

2015-05-01

Context. Tidal interactions between planets and their host stars are not well understood, but may be an important factor in their formation, structure, and evolution. Previous studies suggest that these tidal interactions may be responsible for discrepancies between the ages of exoplanet host stars estimated using stellar models (isochronal age estimates) and age estimates based on the stars' rotation periods (gyrochronological age estimates). Recent improvements in our understanding of the rotational evolution of single stars and a substantial increase in the number of exoplanet host stars with accurate rotation period measurements make it worthwhile to revisit this question. Aims: Our aim is to determine whether the gyrochronological age estimates for transiting exoplanet host stars with accurate rotation period measurements are consistent with their isochronal age estimates, and whether this is indicative of tidal interaction between the planets and their host stars. Methods: We have compiled a sample of 28 transiting exoplanet host stars with measured rotation periods, including two stars (HAT-P-21 and WASP-5) for which the rotation period based on the light curve modulation is reported here for the first time. We use our recently developed Bayesian Markov chain Monte Carlo method to determine the joint posterior distribution for the mass and age of each star in the sample. We extend our Bayesian method to include a calculation of the posterior distribution of the gyrochronological age estimate that accounts for the uncertainties in the mass and age, the strong correlation between these values, and the uncertainties in the mass-rotation-age calibration. Results: The gyrochronological age estimate (τgyro) is significantly lower than the isochronal age estimate for about half of the stars in our sample. Tidal interactions between the star and planet are a reasonable explanation for this discrepancy in some cases, but not all. The distribution of τgyro values is

Usefulness of telomere length in DNA from human teeth for age estimation.

PubMed

Márquez-Ruiz, Ana Belén; González-Herrera, Lucas; Valenzuela, Aurora

2018-03-01

Age estimation is widely used to identify individuals in forensic medicine. However, the accuracy of the most commonly used procedures is markedly reduced in adulthood, and these methods cannot be applied in practice when morphological information is limited. Molecular methods for age estimation have been extensively developed in the last few years. The fact that telomeres shorten at each round of cell division has led to the hypothesis that telomere length can be used as a tool to predict age. The present study thus aimed to assess the correlation between telomere length measured in dental DNA and age, and the effect of sex and tooth type on telomere length; a further aim was to propose a statistical regression model to estimate the biological age based on telomere length. DNA was extracted from 91 tooth samples belonging to 77 individuals of both sexes and 15 to 85 years old and was used to determine telomere length by quantitative real-time PCR. Our results suggested that telomere length was not affected by sex and was greater in molar teeth. We found a significant correlation between age and telomere length measured in DNA from teeth. However, the equation proposed to predict age was not accurate enough for forensic age estimation on its own. Age estimation based on telomere length in DNA from tooth samples may be useful as a complementary method which provides an approximate estimate of age, especially when human skeletal remains are the only forensic sample available.

Stability of individual loudness functions obtained by magnitude estimation and production

NASA Technical Reports Server (NTRS)

Hellman, R. P.

1981-01-01

A correlational analysis of individual magnitude estimation and production exponents at the same frequency is performed, as is an analysis of individual exponents produced in different sessions by the same procedure across frequency (250, 1000, and 3000 Hz). Taken as a whole, the results show that individual exponent differences do not decrease by counterbalancing magnitude estimation with magnitude production and that individual exponent differences remain stable over time despite changes in stimulus frequency. Further results show that although individual magnitude estimation and production exponents do not necessarily obey the .6 power law, it is possible to predict the slope of an equal-sensation function averaged for a group of listeners from individual magnitude estimation and production data. On the assumption that individual listeners with sensorineural hearing also produce stable and reliable magnitude functions, it is also shown that the slope of the loudness-recruitment function measured by magnitude estimation and production can be predicted for individuals with bilateral losses of long duration. Results obtained in normal and pathological ears thus suggest that individual listeners can produce loudness judgements that reveal, although indirectly, the input-output characteristic of the auditory system.

Aspartic acid racemisation in purified elastin from arteries as basis for age estimation.

PubMed

Dobberstein, R C; Tung, S-M; Ritz-Timme, S

2010-07-01

Aspartic acid racemisation (AAR) results in an age-dependent accumulation of D: -aspartic acid in durable human proteins and can be used as a basis for age estimation. Routinely, age estimation based on AAR is performed by analysis of dentine. However, in forensic practise, teeth are not always available. Non-dental tissues for age estimation may be suitable for age estimation based on AAR if they contain durable proteins that can be purified and analysed. Elastin is such a durable protein. To clarify if purified elastin from arteries is a suitable sample for biochemical age estimation, AAR was determined in purified elastin from arteries from individuals of known age (n = 68 individuals, including n = 15 putrefied corpses), considering the influence of different stages of atherosclerosis and putrefaction on the AAR values. AAR was found to increase with age. The relationship between AAR and age was good enough to serve as basis for age estimation, but worse than known from dentinal proteins. Intravital and post-mortem degradation of elastin may have a moderate effect on the AAR values. Age estimation based on AAR in purified elastin from arteries may be a valuable additional tool in the identification of unidentified cadavers, especially in cases where other methods cannot be applied (e.g., no available teeth and body parts).

Estimating age of sea otters with cementum layers in the first premolar

USGS Publications Warehouse

Bodkin, James L.; Ames, J.A.; Jameson, R.J.; Johnson, A.M.; Matson, G.M.

1997-01-01

We assessed sources of variation in the use of tooth cementum layers to determine age by comparing counts in premolar tooth sections to known ages of 20 sea otters (Enhydra lutris). Three readers examined each sample 3 times, and the 3 readings of each sample were averaged by reader to provide the mean estimated age. The mean (SE) of known age sample was 5.2 years (1.0) and the 3 mean estimated ages were 7.0 (1.0), 5.9 (1.1) and, 4.4 (0.8). The proportion of estimates accurate to within +/- 1 year were 0.25, 0.55, and 0.65 and to within +/- 2 years 0.65, 0.80, and 0.70, by reader. The proportions of samples estimated with >3 years error were 0.20, 0.10, and 0.05. Errors as large as 7, 6, and 5 years were made among readers. In few instances did all readers uniformly provide either accurate (error 1 yr) counts. In most cases (0.85), 1 or 2 of the readers provided accurate counts. Coefficients of determination (R2) between known ages and mean estimated ages were 0.81, 0.87, and 0.87, by reader. The results of this study suggest that cementum layers within sea otter premolar teeth likely are deposited annually and can be used for age estimation. However, criteria used in interpreting layers apparently varied by reader, occasionally resulting in large errors, which were not consistent among readers. While large errors were evident for some individual otters, there were no differences between the known and estimated age-class distribution generated by each reader. Until accuracy can be improved, application of this ageing technique should be limited to sample sizes of at least 6-7 individuals within age classes of >/=1 year.

Age Spreads and the Temperature Dependence of Age Estimates in Upper Sco

NASA Astrophysics Data System (ADS)

Fang, Qiliang; Herczeg, Gregory J.; Rizzuto, Aaron

2017-06-01

Past estimates for the age of the Upper Sco Association are typically 11–13 Myr for intermediate-mass stars and 4–5 Myr for low-mass stars. In this study, we simulate populations of young stars to investigate whether this apparent dependence of estimated age on spectral type may be explained by the star formation history of the association. Solar and intermediate mass stars begin their pre-main sequence evolution on the Hayashi track, with fully convective interiors and cool photospheres. Intermediate-mass stars quickly heat up and transition onto the radiative Henyey track. As a consequence, for clusters in which star formation occurs on a timescale similar to that of the transition from a convective to a radiative interior, discrepancies in ages will arise when ages are calculated as a function of temperature instead of mass. Simple simulations of a cluster with constant star formation over several Myr may explain about half of the difference in inferred ages versus photospheric temperature; speculative constructions that consist of a constant star formation followed by a large supernova-driven burst could fully explain the differences, including those between F and G stars where evolutionary tracks may be more accurate. The age spreads of low-mass stars predicted from these prescriptions for star formation are consistent with the observed luminosity spread of Upper Sco. The conclusion that a lengthy star formation history will yield a temperature dependence in ages is expected from the basic physics of pre-main sequence evolution, and is qualitatively robust to the large uncertainties in pre-main sequence evolutionary models.

A comparison of methods used to obtain age ratios of snow and Canada geese

USGS Publications Warehouse

Higgins, K.F.; Linder, R.L.; Springer, P.F.

1969-01-01

The validity of group counts, cannon-net catches, and hunter-bag checks for estimating productivity of lesser snow geese (Anser caerulescens caerulescens) and small Canada geese (Branta canadensis hutchinsii-parvipes complex) was studied at Sand Lake National Wildlife Refuge during the falls of 1965 and 1966. Age ratios of snow geese obtained from net-trapped samples were significantly higher (P < 0.01) than from group counts at the same site. Immature snow geese were shot in a significantly greater (P < 0.01) proportion than they existed in the population as determined by group counts. Cannon-net catches and hunter-bag checks of snow and Canada geese yielded age ratios which were biased because of behavioral characteristics of the geese. Immatures of both species were less wary of trap equipment and immature snow geese were more vulnerable to the gun than adults. It was believed that age ratios from group counts of snow geese were more representative of the population than those from net catches and hunter-bag checks. Sex ratios of net-trapped geese showed a preponderance of males for adult Canada and adult and immature snow geese, whereas females were predominant in the immature segment of Canada geese. Hunter selectivity of blue- or white-phase snow geese was not observed at Sand Lake Refuge. Differential vulnerability to hunting between snow and Canada geese resulted from differences m feeding-flight behavior.

Age and gender estimation using Region-SIFT and multi-layered SVM

NASA Astrophysics Data System (ADS)

Kim, Hyunduk; Lee, Sang-Heon; Sohn, Myoung-Kyu; Hwang, Byunghun

2018-04-01

In this paper, we propose an age and gender estimation framework using the region-SIFT feature and multi-layered SVM classifier. The suggested framework entails three processes. The first step is landmark based face alignment. The second step is the feature extraction step. In this step, we introduce the region-SIFT feature extraction method based on facial landmarks. First, we define sub-regions of the face. We then extract SIFT features from each sub-region. In order to reduce the dimensions of features we employ a Principal Component Analysis (PCA) and a Linear Discriminant Analysis (LDA). Finally, we classify age and gender using a multi-layered Support Vector Machines (SVM) for efficient classification. Rather than performing gender estimation and age estimation independently, the use of the multi-layered SVM can improve the classification rate by constructing a classifier that estimate the age according to gender. Moreover, we collect a dataset of face images, called by DGIST_C, from the internet. A performance evaluation of proposed method was performed with the FERET database, CACD database, and DGIST_C database. The experimental results demonstrate that the proposed approach classifies age and performs gender estimation very efficiently and accurately.

Age Estimation of African Lions Panthera leo by Ratio of Tooth Areas.

PubMed

White, Paula A; Ikanda, Dennis; Ferrante, Luigi; Chardonnet, Philippe; Mesochina, Pascal; Cameriere, Roberto

2016-01-01

Improved age estimation of African lions Panthera leo is needed to address a number of pressing conservation issues. Here we present a formula for estimating lion age to within six months of known age based on measuring the extent of pulp closure from X-rays, or Ratio Of tooth AReas (ROAR). Derived from measurements taken from lions aged 3-13 years for which exact ages were known, the formula explains 92% of the total variance. The method of calculating the pulp/tooth area ratio, which has been used extensively in forensic science, is novel in the study of lion aging. As a quantifiable measure, ROAR offers improved lion age estimates for population modeling and investigations of age-related mortality, and may assist national and international wildlife authorities in judging compliance with regulatory measures involving age.

Estimating the formation age distribution of continental crust by unmixing zircon ages

NASA Astrophysics Data System (ADS)

Korenaga, Jun

2018-01-01

Continental crust provides first-order control on Earth's surface environment, enabling the presence of stable dry landmasses surrounded by deep oceans. The evolution of continental crust is important for atmospheric evolution, because continental crust is an essential component of deep carbon cycle and is likely to have played a critical role in the oxygenation of the atmosphere. Geochemical information stored in the mineral zircon, known for its resilience to diagenesis and metamorphism, has been central to ongoing debates on the genesis and evolution of continental crust. However, correction for crustal reworking, which is the most critical step when estimating original formation ages, has been incorrectly formulated, undermining the significance of previous estimates. Here I suggest a simple yet promising approach for reworking correction using the global compilation of zircon data. The present-day distribution of crustal formation age estimated by the new "unmixing" method serves as the lower bound to the true crustal growth, and large deviations from growth models based on mantle depletion imply the important role of crustal recycling through the Earth history.

Gestational age estimation on United States livebirth certificates: a historical overview.

PubMed

Wier, Megan L; Pearl, Michelle; Kharrazi, Martin

2007-09-01

Gestational age on the birth certificate is the most common source of population-based gestational age data that informs public health policy and practice in the US. Last menstrual period is one of the oldest methods of gestational age estimation and has been on the US Standard Certificate of Live Birth since 1968. The 'clinical estimate of gestation', added to the standard certificate in 1989 to address missing or erroneous last menstrual period data, was replaced by the 'obstetric estimate of gestation' on the 2003 revision, which specifically precludes neonatal assessments. We discuss the strengths and weaknesses of these measures, potential research implications and challenges accompanying the transition to the obstetric estimate.

Estimating age at a specified length from the von Bertalanffy growth function

USGS Publications Warehouse

Ogle, Derek H.; Isermann, Daniel A.

2017-01-01

Estimating the time required (i.e., age) for fish in a population to reach a specific length (e.g., legal harvest length) is useful for understanding population dynamics and simulating the potential effects of length-based harvest regulations. The age at which a population reaches a specific mean length is typically estimated by fitting a von Bertalanffy growth function to length-at-age data and then rearranging the best-fit equation to solve for age at the specified length. This process precludes the use of standard frequentist methods to compute confidence intervals and compare estimates of age at the specified length among populations. We provide a parameterization of the von Bertalanffy growth function that has age at a specified length as a parameter. With this parameterization, age at a specified length is directly estimated, and standard methods can be used to construct confidence intervals and make among-group comparisons for this parameter. We demonstrate use of the new parameterization with two data sets.

Estimating time-based instantaneous total mortality rate based on the age-structured abundance index

NASA Astrophysics Data System (ADS)

Wang, Yingbin; Jiao, Yan

2015-05-01

The instantaneous total mortality rate ( Z) of a fish population is one of the important parameters in fisheries stock assessment. The estimation of Z is crucial to fish population dynamics analysis, abundance and catch forecast, and fisheries management. A catch curve-based method for estimating time-based Z and its change trend from catch per unit effort (CPUE) data of multiple cohorts is developed. Unlike the traditional catch-curve method, the method developed here does not need the assumption of constant Z throughout the time, but the Z values in n continuous years are assumed constant, and then the Z values in different n continuous years are estimated using the age-based CPUE data within these years. The results of the simulation analyses show that the trends of the estimated time-based Z are consistent with the trends of the true Z, and the estimated rates of change from this approach are close to the true change rates (the relative differences between the change rates of the estimated Z and the true Z are smaller than 10%). Variations of both Z and recruitment can affect the estimates of Z value and the trend of Z. The most appropriate value of n can be different given the effects of different factors. Therefore, the appropriate value of n for different fisheries should be determined through a simulation analysis as we demonstrated in this study. Further analyses suggested that selectivity and age estimation are also two factors that can affect the estimated Z values if there is error in either of them, but the estimated change rates of Z are still close to the true change rates. We also applied this approach to the Atlantic cod ( Gadus morhua) fishery of eastern Newfoundland and Labrador from 1983 to 1997, and obtained reasonable estimates of time-based Z.

Fully automatic bone age estimation from left hand MR images.

PubMed

Stern, Darko; Ebner, Thomas; Bischof, Horst; Grassegger, Sabine; Ehammer, Thomas; Urschler, Martin

2014-01-01

There has recently been an increased demand in bone age estimation (BAE) of living individuals and human remains in legal medicine applications. A severe drawback of established BAE techniques based on X-ray images is radiation exposure, since many countries prohibit scanning involving ionizing radiation without diagnostic reasons. We propose a completely automated method for BAE based on volumetric hand MRI images. On our database of 56 male caucasian subjects between 13 and 19 years, we are able to estimate the subjects age with a mean difference of 0.85 ± 0.58 years compared to the chronological age, which is in line with radiologist results using established radiographic methods. We see this work as a promising first step towards a novel MRI based bone age estimation system, with the key benefits of lacking exposure to ionizing radiation and higher accuracy due to exploitation of volumetric data.

The reliability of Fishman method of skeletal maturation for age estimation in children of South Indian population

PubMed Central

Mohammed, Rezwana Begum; Kalyan, V. Siva; Tircouveluri, Saritha; Vegesna, Goutham Chakravarthy; Chirla, Anil; Varma, D. Maruthi

2014-01-01

Introduction: Determining the age of a person in the absence of documentary evidence of birth is essential for legal and medico-legal purpose. Fishman method of skeletal maturation is widely used for this purpose; however, the reliability of this method for people with all geographic locations is not well-established. Aims and Objectives: In this study, we assessed various stages of carpal and metacarpal bone maturation and tested the reliability of Fishman method of skeletal maturation to estimate the age in South Indian population. We also evaluated the correlation between the chronological age (CA) and predicted age based on the Fishman method of skeletal maturation. Materials and Methods: Digital right hand-wrist radiographs of 330 individuals aged 9-20 years were obtained and the skeletal maturity stage for each subject was determined using Fishman method. The skeletal maturation indicator scores were obtained and analyzed with reference to CA and sex. Data was analyzed using the SPSS software package (version 12, SPSS Inc., Chicago, IL, USA). Results: The study subjects had a tendency toward late maturation with the mean skeletal age (SA) estimated being significantly lowers (P < 0.05) than the mean CA at various skeletal maturity stages. Nevertheless, significant correlation was observed in this study between SA and CA for males (r = 0.82) and females (r = 0.85). Interestingly, female subjects were observed to be advanced in SA compared with males. Conclusion: Fishman method of skeletal maturation can be used as an alternative tool for the assessment of mean age of an individual of unknown CA in South Indian children. PMID:25097402

The reliability of Fishman method of skeletal maturation for age estimation in children of South Indian population.

PubMed

Mohammed, Rezwana Begum; Kalyan, V Siva; Tircouveluri, Saritha; Vegesna, Goutham Chakravarthy; Chirla, Anil; Varma, D Maruthi

2014-07-01

Determining the age of a person in the absence of documentary evidence of birth is essential for legal and medico-legal purpose. Fishman method of skeletal maturation is widely used for this purpose; however, the reliability of this method for people with all geographic locations is not well-established. In this study, we assessed various stages of carpal and metacarpal bone maturation and tested the reliability of Fishman method of skeletal maturation to estimate the age in South Indian population. We also evaluated the correlation between the chronological age (CA) and predicted age based on the Fishman method of skeletal maturation. Digital right hand-wrist radiographs of 330 individuals aged 9-20 years were obtained and the skeletal maturity stage for each subject was determined using Fishman method. The skeletal maturation indicator scores were obtained and analyzed with reference to CA and sex. Data was analyzed using the SPSS software package (version 12, SPSS Inc., Chicago, IL, USA). The study subjects had a tendency toward late maturation with the mean skeletal age (SA) estimated being significantly lowers (P < 0.05) than the mean CA at various skeletal maturity stages. Nevertheless, significant correlation was observed in this study between SA and CA for males (r = 0.82) and females (r = 0.85). Interestingly, female subjects were observed to be advanced in SA compared with males. Fishman method of skeletal maturation can be used as an alternative tool for the assessment of mean age of an individual of unknown CA in South Indian children.

Age Estimation Based on Children's Voice: A Fuzzy-Based Decision Fusion Strategy

PubMed Central

Ting, Hua-Nong

2014-01-01

Automatic estimation of a speaker's age is a challenging research topic in the area of speech analysis. In this paper, a novel approach to estimate a speaker's age is presented. The method features a “divide and conquer” strategy wherein the speech data are divided into six groups based on the vowel classes. There are two reasons behind this strategy. First, reduction in the complicated distribution of the processing data improves the classifier's learning performance. Second, different vowel classes contain complementary information for age estimation. Mel-frequency cepstral coefficients are computed for each group and single layer feed-forward neural networks based on self-adaptive extreme learning machine are applied to the features to make a primary decision. Subsequently, fuzzy data fusion is employed to provide an overall decision by aggregating the classifier's outputs. The results are then compared with a number of state-of-the-art age estimation methods. Experiments conducted based on six age groups including children aged between 7 and 12 years revealed that fuzzy fusion of the classifier's outputs resulted in considerable improvement of up to 53.33% in age estimation accuracy. Moreover, the fuzzy fusion of decisions aggregated the complementary information of a speaker's age from various speech sources. PMID:25006595

Cost-Sensitive Local Binary Feature Learning for Facial Age Estimation.

PubMed

Lu, Jiwen; Liong, Venice Erin; Zhou, Jie

2015-12-01

In this paper, we propose a cost-sensitive local binary feature learning (CS-LBFL) method for facial age estimation. Unlike the conventional facial age estimation methods that employ hand-crafted descriptors or holistically learned descriptors for feature representation, our CS-LBFL method learns discriminative local features directly from raw pixels for face representation. Motivated by the fact that facial age estimation is a cost-sensitive computer vision problem and local binary features are more robust to illumination and expression variations than holistic features, we learn a series of hashing functions to project raw pixel values extracted from face patches into low-dimensional binary codes, where binary codes with similar chronological ages are projected as close as possible, and those with dissimilar chronological ages are projected as far as possible. Then, we pool and encode these local binary codes within each face image as a real-valued histogram feature for face representation. Moreover, we propose a cost-sensitive local binary multi-feature learning method to jointly learn multiple sets of hashing functions using face patches extracted from different scales to exploit complementary information. Our methods achieve competitive performance on four widely used face aging data sets.

Age Estimation of African Lions Panthera leo by Ratio of Tooth Areas

PubMed Central

Ikanda, Dennis; Ferrante, Luigi; Chardonnet, Philippe; Mesochina, Pascal; Cameriere, Roberto

2016-01-01

Improved age estimation of African lions Panthera leo is needed to address a number of pressing conservation issues. Here we present a formula for estimating lion age to within six months of known age based on measuring the extent of pulp closure from X-rays, or Ratio Of tooth AReas (ROAR). Derived from measurements taken from lions aged 3–13 years for which exact ages were known, the formula explains 92% of the total variance. The method of calculating the pulp/tooth area ratio, which has been used extensively in forensic science, is novel in the study of lion aging. As a quantifiable measure, ROAR offers improved lion age estimates for population modeling and investigations of age-related mortality, and may assist national and international wildlife authorities in judging compliance with regulatory measures involving age. PMID:27089506

Comparison of rainbow smelt age estimates from fin rays and otoliths

USGS Publications Warehouse

Walsh, M.G.; Maloy, A.P.; O'Brien, T. P.

2008-01-01

Rainbow smelt Osmerus mordax, although nonnative, are an important component of the offshore food web in the Laurentian Great Lakes. In Lake Ontario, we estimate ages of rainbow smelt annually to study population dynamics such as year-class strength and age-specific growth and mortality. Since the early 1980s, we have used pectoral fin rays to estimate rainbow smelt ages, but the sectioning and mounting of fin rays are time and labor intensive. Our objective was to assess the feasibility of using otoliths rather than fin rays to estimate rainbow smelt ages. Three readers interpreted the ages of 172 rainbow smelt (60-198 mm total length) based on thin sections of pectoral fin rays, whole otoliths with no preparation, and whole otoliths that had been cleared for 1 month in a 70:30 ethanol : glycerin solution. Bias was lower and precision was greater for fin rays than for otoliths; these results were consistent for comparisons within readers (first and second readings by one individual; three readers were used) and between readers (one reading for each reader within a pair). Both otolith methods appeared to misclassify age-1 rainbow smelt. Fin ray ages had the highest precision and provided the best approximation of age estimates inferred from the Lake Ontario population's length frequency distribution and from our understanding of this population. ?? American Fisheries Society 2008.

Egg flotation estimates nest age for Pacific and Red-throated Loons

USGS Publications Warehouse

Rizzolo, Daniel; Schmutz, Joel A.

2007-01-01

We used Pacific Loon (Gavia pacifica) and Red-throated Loon (G. stellata) nests with known ages to gauge the efficacy of egg flotation for determining nest age in coastal Alaska. Egg flotation accurately estimated nest age for both species; the mean ± 1SD difference between known age and age determined with egg flotation was - 0.05 ± 2.00 d and -0.02 ± 1.63 d for Pacific and Red-throated Loons, respectively. Day of nest initiation did not influence the relationship between known nest age and nest age estimated with egg flotation, indicating incubation period was not shortened in nests initiated later in the season. Additionally, we found no difference in the ability of egg flotation to estimate nest age between two widely dispersed study sites for Pacific Loons, and only a small difference between two of three widely dispersed study sites for Red-throated Loons. Thus, our described relationships between egg flotation categories and nest age should be broadly applicable for these holarctic species. We conclude that for Pacific and Red-throated Loons, egg flotation is a useful technique for determining nest age in the field to better monitor nest fate, and to quantify nest age effects on nest daily survival rate.

Effects of a growth check on daily age estimates of age-0 alligator gar

USGS Publications Warehouse

Snow, Richard A.; Long, James M.

2016-01-01

Accurate age and growth information is essential for a complete knowledge of life history, growth rates, age at sexual maturity, and average life span in fishes. Alligator gar are becoming increasingly managed throughout their range and because this species spawns in backwater flooded areas, their offspring are prone to stranding in areas with limited prey, potentially affecting their growth. Because fish growth is tightly linked with otolith growth and annulus formation, the ability to discern marks not indicative of annuli (age checks) in alligator gar would give managers some insight when estimating ages. Previous studies have suggested that checks are often present prior to the first annulus in otoliths of alligator gar, affecting age estimates. We investigated check formation in otoliths of alligator gar in relation to growth and food availability. Sixteen age-0 alligator gar were marked with oxytetracycline (OTC) to give a reference point and divided equitably into two groups: a control group with abundant prey and an experimental group with limited prey. The experimental group was given 2 g of food per week for 20 days and then given the same prey availability as the control group for the next 20 days. After 40 days, the gar were measured, sacrificed, and their sagittae removed to determine if checks were present. Checks were visible on 14 of the 16 otoliths in the experimental group, associated with low growth during the first 20 days when prey was limited and accelerated growth after prey availability was increased. No checks were observed on otoliths of the control group, where growth and prey availability were consistent. Age estimates of fish in the control group were more accurate than those in the experimental group, showing that fish growth as a function of prey availability likely induced the checks by compressing daily ring formation.

Age estimation from dental cementum incremental lines and periodontal disease.

PubMed

Dias, P E M; Beaini, T L; Melani, R F H

2010-12-01

Age estimation by counting incremental lines in cementum added to the average age of tooth eruption is considered an accurate method by some authors, while others reject it stating weak correlation between estimated and actual age. The aim of this study was to evaluate this technique and check the influence of periodontal disease on age estimates by analyzing both the number of cementum lines and the correlation between cementum thickness and actual age on freshly extracted teeth. Thirty one undecalcified ground cross sections of approximately 30 µm, from 25 teeth were prepared, observed, photographed and measured. Images were enhanced by software and counts were made by one observer, and the results compared with two control-observers. There was moderate correlation ((r)=0.58) for the entire sample, with mean error of 9.7 years. For teeth with periodontal pathologies, correlation was 0.03 with a mean error of 22.6 years. For teeth without periodontal pathologies, correlation was 0.74 with mean error of 1.6 years. There was correlation of 0.69 between cementum thickness and known age for the entire sample, 0.25 for teeth with periodontal problems and 0.75 for teeth without periodontal pathologies. The technique was reliable for periodontally sound teeth, but not for periodontally diseased teeth.

Forensic age estimation using computed tomography of the medial clavicular epiphysis: a systematic review.

PubMed

Hermetet, Coralie; Saint-Martin, Pauline; Gambier, Arsène; Ribier, Léo; Sautenet, Bénédicte; Rérolle, Camille

2018-04-30

Medicolegal physicians are increasingly called upon to aid in determining the administrative age group affiliation of refugees with questionable unaccompanied minor claims. According to guidelines for forensic age assessment, age differentiation along the 18-year-old cut-off relies on clavicular ossification. The thin-slice computed tomography scan (TSCTs) of the medial clavicular epiphysis (MCE) is one of the methods contributing to this assessment, though it is not yet universally accepted. The aim of this systematic review was to identify scientific papers where age was assessed using TSCTs of the MCE and to observe whether this examination was reproducible and reliable in estimating a person's age relative to the 18-year-old threshold. A search algorithm was applied to several databases to identify articles in accordance with the PRISMA (Preferred Reporting Items for Systematic-Reviews and Meta-Analyses) statement. One boxplot per article was constructed, separating by stage of maturation and sex. The 13 articles selected represented a sample of 5605 individuals (3396 males, 2209 females) aged 10 to 35 years. All individuals classified as stages 4 and 5 were aged 18 years or older. The same result was obtained concerning stage 3c, except in one article. The results thus appear reliable and reproducible, in particular, with respect to the 18-year-old threshold; medicolegal physicians should be able to estimate that all individuals in stages 4 and 5 are at least 18 years old. Additional studies applied to several other populations in the world should complement the selected studies.

Development of a biometric method to estimate age on hand radiographs.

PubMed

Remy, Floriane; Hossu, Gabriela; Cendre, Romain; Micard, Emilien; Mainard-Simard, Laurence; Felblinger, Jacques; Martrille, Laurent; Lalys, Loïc

2017-02-01

Age estimation of living individuals aged less than 13, 18 or 21 years, which are some relevant legal ages in most European countries, is currently problematic in the forensic context. Thus, numerous methods are available for legal authorities, although their efficiency can be discussed. For those reasons, we aimed to propose a new method, based on the biometric analysis of hand bones. 451 hand radiographs of French individuals under the age of 21 were retrospectively analyzed. This total sample was divided into three subgroups bounded by the relevant legal ages previously mentioned: 0-13, 13-18 and 18-21 years. On these radiographs, we numerically applied the osteometric board method used in anthropology, by including each metacarpal and proximal phalange of the five hand rays in the smallest rectangle possible. In that we can access their length and width information thanks to a measurement protocol developed precisely for our treatment with the ORS Visual ® software. Then, a statistical analysis was performed from these biometric data: a Linear Discriminant Analysis (LDA) evaluated the probability for an individual to belong to one of the age group (0-13, 13-18 or 18-21); and several multivariate regression models were tested for the establishment of age estimation formulas for each of these age groups. The mean Correlation Coefficient between chronological age and both lengths and widths of hand bones is equal to 0.90 for the total sample. Repeatability and reproducibility were assessed. The LDA could more easily predict the belonging to the 0-13 age group. Age can be estimated with a mean standard error which never exceeds 1 year for the 95% confidence interval. Finally, compared to the literature, we can conclude that estimating an age from the biometric information of metacarpals and proximal phalanges is promising. Copyright © 2016. Published by Elsevier B.V.

Maximum likelihood estimation for predicting the probability of obtaining variable shortleaf pine regeneration densities

Treesearch

Thomas B. Lynch; Jean Nkouka; Michael M. Huebschmann; James M. Guldin

2003-01-01

A logistic equation is the basis for a model that predicts the probability of obtaining regeneration at specified densities. The density of regeneration (trees/ha) for which an estimate of probability is desired can be specified by means of independent variables in the model. When estimating parameters, the dependent variable is set to 1 if the regeneration density (...

Lake Erie Yellow perch age estimation based on three structures: Precision, processing times, and management implications

USGS Publications Warehouse

Vandergoot, C.S.; Bur, M.T.; Powell, K.A.

2008-01-01

Yellow perch Perca flavescens support economically important recreational and commercial fisheries in Lake Erie and are intensively managed. Age estimation represents an integral component in the management of Lake Erie yellow perch stocks, as age-structured population models are used to set safe harvest levels on an annual basis. We compared the precision associated with yellow perch (N = 251) age estimates from scales, sagittal otoliths, and anal spine sections and evaluated the time required to process and estimate age from each structure. Three readers of varying experience estimated ages. The precision (mean coefficient of variation) of estimates among readers was 1% for sagittal otoliths, 5-6% for anal spines, and 11-13% for scales. Agreement rates among readers were 94-95% for otoliths, 71-76% for anal spines, and 45-50% for scales. Systematic age estimation differences were evident among scale and anal spine readers; less-experienced readers tended to underestimate ages of yellow perch older than age 4 relative to estimates made by an experienced reader. Mean scale age tended to underestimate ages of age-6 and older fish relative to otolith ages estimated by an experienced reader. Total annual mortality estimates based on scale ages were 20% higher than those based on otolith ages; mortality estimates based on anal spine ages were 4% higher than those based on otolith ages. Otoliths required more removal and preparation time than scales and anal spines, but age estimation time was substantially lower for otoliths than for the other two structures. We suggest the use of otoliths or anal spines for age estimation in yellow perch (regardless of length) from Lake Erie and other systems where precise age estimates are necessary, because age estimation errors resulting from the use of scales could generate incorrect management decisions. ?? Copyright by the American Fisheries Society 2008.

Accuracy of MRI skeletal age estimation for subjects 12-19. Potential use for subjects of unknown age.

PubMed

Serinelli, Serenella; Panebianco, Valeria; Martino, Milvia; Battisti, Sofia; Rodacki, Karina; Marinelli, Enrico; Zaccagna, Fulvio; Semelka, Richard C; Tomei, Ernesto

2015-05-01

In forensic practice, there is a growing need for accurate methods of age estimation, especially in the cases of young individuals of unknown age. Age can be estimated through somatic features that are universally considered associated with chronological age. Unfortunately, these features do not always coincide with the real chronological age: for these reasons that age determination is often very difficult. Our aim is to evaluate accuracy of skeletal age estimation using Tomei's MRI method in subjects between 12 and 19 years old for forensic purposes. Two investigators analyzed MRI images of the left hand and wrist of 77 male and 74 female caucasian subjects, without chronic diseases or developmental disorders, whose age ranged from 12 to 19 years. Skeletal maturation was determined by two operators, who analyzed all MRI images separately, in blinded fashion to the chronological age. Inter-rater agreement was measured with Pearson (R (2)) coefficient. One of the examiners repeated the evaluation after 6 months, and intraobserver variation was analyzed. Bland-Altman plots were used to determine mean differences between skeletal and chronological age. Inter-rater agreement Pearson coefficient showed a good linear correlation, respectively, 0.98 and 0.97 in males and females. Bland-Altman analysis demonstrated that the differences between chronological and skeletal age are not significant. Spearman's correlation coefficient showed good correlation between skeletal and chronological age both in females (R (2) = 0.96) and in males (R (2) = 0.94). Our results show that MRI skeletal age is a reproducible method and has good correlation with chronological age.

Non-working nurses in Japan: estimated size and its age-cohort characteristics.

PubMed

Nakata, Yoshifumi; Miyazaki, Satoru

2008-12-01

This paper aims to forecast the total number of non-working nursing staff in Japan both overall and in terms of separate age groups for assistant nurses and fully qualified nurses. This also examines policy implications of those forecasts. Although the existence of around 550,000 of non-working nursing staff has been announced, the actual number of non-working nurses is not so clear that we might make errors in making policy to meet nurse workforce demand and supply in Japan. Estimations by integrating various data on the quantitative characteristics of non-working nursing staff were carried out. Considering the length and the type of education or training in referred four nursing positions; registered nurses, assistant nurses, public health nurses and midwives, we first estimated the number of students who completed a full course. And then multiplying by the ratio for gender and age classifications at the time of entry into courses, the number of those who obtained licenses was estimated. The number of non-working nurses was estimated at 100,000 higher than those in 2005 by government. Looking at age group, it is also possible to see a strong reflection of an employment pattern that follows the life cycle of female workers. Further analysis of life cycle effects and cohort effects proved the effect of life cycles even when subtracting the differences between the working behaviours of different generations. Our findings strongly suggest the need to provide an urgent policy that workplace conditions can be created in which a balance between work and family is achievable. Moreover, to empower clinical activity, we also believe there is an urgent need to reexamine the overall career vision for assistant nurses including in terms of compensation. Relevance to clinical practice. Our findings strongly suggests that consideration for work-life balance of nursing staff; particularly, female staff is all the more important to provide a stable quality care.

Estimating a child's age from an image using whole body proportions.

PubMed

Lucas, Teghan; Henneberg, Maciej

2017-09-01

The use and distribution of child pornography is an increasing problem. Forensic anthropologists are often asked to estimate a child's age from a photograph. Previous studies have attempted to estimate the age of children from photographs using ratios of the face. Here, we propose to include body measurement ratios into age estimates. A total of 1603 boys and 1833 girls aged 5-16 years were measured over a 10-year period. They are 'Cape Coloured' children from South Africa. Their age was regressed on ratios derived from anthropometric measurements of the head as well as the body. Multiple regression equations including four ratios for each sex (head height to shoulder and hip width, knee width, leg length and trunk length) have a standard error of 1.6-1.7 years. The error is of the same order as variation of differences between biological and chronological ages of the children. Thus, the error cannot be minimised any further as it is a direct reflection of a naturally occurring phenomenon.

Is Greulich and Pyle standards of skeletal maturation applicable for age estimation in South Indian Andhra children?

PubMed

Mohammed, Rezwana Begum; Rao, Dola Srinivasa; Goud, Alampur Srinivas; Sailaja, S; Thetay, Anshuj Ajay Rao; Gopalakrishnan, Meera

2015-01-01

Now-a-day age determination has gained importance for various forensic and legal reasons. Skeletal age (SA) of a test population can be estimated by comparing with established standards of Greulich and Pyle (G-P). As this atlas has been prepared using data from upper-class children born between 1917 and 1942 in the USA and the applicability of these standards to contemporary populations has yet to be tested on Andhra children living in India. Hence, this study was aimed to assess the reliability of bone age calculated by G-P atlas in estimation of age in selected population. A total of 660 children (330 girls, 330 boys) between ages 9 and 20 years were randomly selected from outpatient Department of Oral Medicine in GITAM Dental College, Andhra Pradesh. Digital hand-wrist radiographs were obtained and assessed for SA using G-P atlas and the difference between estimated SA and chronological age (CA) were compared with paired t-test and Wilcoxon signed rank test. G-P method underestimated the SA by 0.23 ± 1.53 years for boys and overestimated SA by 0.02 ± 2 years in girls and mild underestimation was noted in the total sample of about 0.1 ± 1.78 years. Spearman rank test showed significant correlation between SA and CA (r = 0.86; P < 0.001). This study concluded that G-P standards were reliable in assessing age in South Indian Andhra children of age 9-20 years with unknown CA.

An overview of age estimation in forensic anthropology: perspectives and practical considerations.

PubMed

Márquez-Grant, Nicholas

2015-01-01

Information on methods of age estimation in physical anthropology, in particular with regard to age-at-death from human skeletal remains, is widely available in the literature. However, the practicalities and real challenges faced in forensic casework are not always highlighted. To provide a practitioner's perspective, regarding age estimation in forensic anthropology (both in the living as well as the dead), with an emphasis on the types of cases, the value of such work and its challenges and limitations. The paper reviews the current literature on age estimation with a focus on forensic anthropology, but it also brings the author's personal perspective derived from a number of forensic cases. Although much is known about what methods to use, but not always how to apply them, little attention has been given in the literature to the real practicalities faced by forensic anthropologists, for example: the challenges in different types of scenarios; how to report age estimations; responsibilities; and ethical concerns. This paper gathers some of these aspects into one overview which includes the value of such work and the practical challenges, not necessarily with the methods themselves, but also with regard to how these are applied in the different cases where age estimation is required.

Recollection, not familiarity, decreases in healthy aging: Converging evidence from four estimation methods

PubMed Central

Koen, Joshua D.; Yonelinas, Andrew P.

2014-01-01

Although it is generally accepted that aging is associated with recollection impairments, there is considerable disagreement surrounding how healthy aging influences familiarity-based recognition. One factor that might contribute to the mixed findings regarding age differences in familiarity is the estimation method used to quantify the two mnemonic processes. Here, this issue is examined by having a group of older adults (N = 39) between 40 and 81 years of age complete Remember/Know (RK), receiver operating characteristic (ROC), and process dissociation (PD) recognition tests. Estimates of recollection, but not familiarity, showed a significant negative correlation with chronological age. Inconsistent with previous findings, the estimation method did not moderate the relationship between age and estimations of recollection and familiarity. In a final analysis, recollection and familiarity were estimated as latent factors in a confirmatory factor analysis (CFA) that modeled the covariance between measures of free recall and recognition, and the results converged with the results from the RK, PD, and ROC tasks. These results are consistent with the hypothesis that episodic memory declines in older adults are primary driven by recollection deficits, and also suggest that the estimation method plays little to no role in age-related decreases in familiarity. PMID:25485974

Applying Deep Learning in Medical Images: The Case of Bone Age Estimation.

PubMed

Lee, Jang Hyung; Kim, Kwang Gi

2018-01-01

A diagnostic need often arises to estimate bone age from X-ray images of the hand of a subject during the growth period. Together with measured physical height, such information may be used as indicators for the height growth prognosis of the subject. We present a way to apply the deep learning technique to medical image analysis using hand bone age estimation as an example. Age estimation was formulated as a regression problem with hand X-ray images as input and estimated age as output. A set of hand X-ray images was used to form a training set with which a regression model was trained. An image preprocessing procedure is described which reduces image variations across data instances that are unrelated to age-wise variation. The use of Caffe, a deep learning tool is demonstrated. A rather simple deep learning network was adopted and trained for tutorial purpose. A test set distinct from the training set was formed to assess the validity of the approach. The measured mean absolute difference value was 18.9 months, and the concordance correlation coefficient was 0.78. It is shown that the proposed deep learning-based neural network can be used to estimate a subject's age from hand X-ray images, which eliminates the need for tedious atlas look-ups in clinical environments and should improve the time and cost efficiency of the estimation process.

A critique of age estimation using attrition as the sole indicator.

PubMed

Ball, J

2002-12-01

The age determination of skeletal remains has been carried out using anthropological examination of the remaining bones and dentition. The aging of the dentition is based on attrition which, if physiological will correlate with age. Occasionally the only material available is a single tooth or a few teeth, or in the case of a living person, teeth in situ. In certain cases microscopic examination of the teeth may not be possible and the age estimation is then often determined by the degree of attrition associated with the tooth. In more recent times the causes of attrition have involved other factors such as bruxism, diet, environment and medication. The weaknesses and limitations of age estimation by examination of dental attrition as the sole indicator of age are highlighted.

Economic productivity by age and sex: 2007 estimates for the United States.

PubMed

Grosse, Scott D; Krueger, Kurt V; Mvundura, Mercy

2009-07-01

Human capital estimates of labor productivity are often used to estimate the economic impact of diseases and injuries that cause incapacitation or death. Estimates of average hourly, annual, and lifetime economic productivity, both market and household, were calculated in 2007 US dollars for 5-year age groups for men, women, and both sexes in the United States. Data from the American Time Use Survey were used to estimate hours of paid work and household services and hourly and annual earnings and household productivity. Present values of discounted lifetime earnings were calculated for each age group using the 2004 US life tables and a discount rate of 3% per year and assuming future productivity growth of 1% per year. The estimates of hours and productivity were calculated using the time diaries of 72,922 persons included in the American Time Use Survey for the years 2003 to 2007. The present value of lifetime productivity is approximately $1.2 million in 2007 dollars for children under 5 years of age. For adults in their 20s and 30s, it is approximately $1.6 million and then it declines with increasing age. Productivity estimates are higher for males than for females, more for market productivity than for total productivity. Changes in hours of paid employment and household services can affect economic productivity by age and sex. This is the first publication to include estimates of household services based on contemporary time use data for the US population.

Dental computed tomographic imaging as age estimation: morphological analysis of the third molar of a group of Turkish population.

PubMed

Cantekin, Kenan; Sekerci, Ahmet Ercan; Buyuk, Suleyman Kutalmis

2013-12-01

Computed tomography (CT) is capable of providing accurate and measurable 3-dimensional images of the third molar. The aims of this study were to analyze the development of the mandibular third molar and its relation to chronological age and to create new reference data for a group of Turkish participants aged 9 to 25 years on the basis of cone-beam CT images. All data were obtained from the patients' records including medical, social, and dental anamnesis and cone-beam CT images of 752 patients. Linear regression analysis was performed to obtain regression formulas for dental age calculation with chronological age and to determine the coefficient of determination (r) for each sex. Statistical analysis showed a strong correlation between age and third-molar development for the males (r2 = 0.80) and the females (r2 = 0.78). Computed tomographic images are clinically useful for accurate and reliable estimation of dental ages of children and youth.

Obtaining Cue Rate Estimates for Some Mysticete Species using Existing Data

DTIC Science & Technology

2014-09-30

primary focus is to obtain cue rates for humpback whales (Megaptera novaeangliae) off the California coast and on the PMRF range. To our knowledge, no... humpback whale cue rates have been calculated for these populations. Once a cue rate is estimated for the populations of humpback whales off the...rates for humpback whales on breeding grounds, in addition to average cue rates for other species of mysticete whales . Cue rates of several other

Reliability of fish size estimates obtained from multibeam imaging sonar

USGS Publications Warehouse

Hightower, Joseph E.; Magowan, Kevin J.; Brown, Lori M.; Fox, Dewayne A.

2013-01-01

Multibeam imaging sonars have considerable potential for use in fisheries surveys because the video-like images are easy to interpret, and they contain information about fish size, shape, and swimming behavior, as well as characteristics of occupied habitats. We examined images obtained using a dual-frequency identification sonar (DIDSON) multibeam sonar for Atlantic sturgeon Acipenser oxyrinchus oxyrinchus, striped bass Morone saxatilis, white perch M. americana, and channel catfish Ictalurus punctatus of known size (20–141 cm) to determine the reliability of length estimates. For ranges up to 11 m, percent measurement error (sonar estimate – total length)/total length × 100 varied by species but was not related to the fish's range or aspect angle (orientation relative to the sonar beam). Least-square mean percent error was significantly different from 0.0 for Atlantic sturgeon (x̄  =  −8.34, SE  =  2.39) and white perch (x̄  = 14.48, SE  =  3.99) but not striped bass (x̄  =  3.71, SE  =  2.58) or channel catfish (x̄  = 3.97, SE  =  5.16). Underestimating lengths of Atlantic sturgeon may be due to difficulty in detecting the snout or the longer dorsal lobe of the heterocercal tail. White perch was the smallest species tested, and it had the largest percent measurement errors (both positive and negative) and the lowest percentage of images classified as good or acceptable. Automated length estimates for the four species using Echoview software varied with position in the view-field. Estimates tended to be low at more extreme azimuthal angles (fish's angle off-axis within the view-field), but mean and maximum estimates were highly correlated with total length. Software estimates also were biased by fish images partially outside the view-field and when acoustic crosstalk occurred (when a fish perpendicular to the sonar and at relatively close range is detected in the side lobes of adjacent beams). These sources of

[The importance of memory bias in obtaining age of menarche by recall method in Brazilian adolescents].

PubMed

Castilho, Silvia Diez; Nucci, Luciana Bertoldi; Assuino, Samanta Ramos; Hansen, Lucca Ortolan

2014-06-01

To compare the age at menarche obtained by recall method according to the time elapsed since the event, in order to verify the importance of the recall bias. Were evaluated 1,671 girls (7-18 years) at schools in Campinas-SP regarding the occurrence of menarche by the status quo method (menarche: yes or no) and the recall method (date of menarche, for those who mentioned it). The age at menarche obtained by the status quo method was calculated by logit, which considers the whole group, and the age obtained by the recall method was calculated as the average of the mentioned age at menarche. In this group, the age at menarche was obtained by the difference between the date of the event and the date of birth. Girls who reported menarche (883, 52.8%) were divided into four groups according to the time elapsed since the event. To analyze the results, we used ANOVA and logistic regression for the analysis, with a significance level of 0.05. The age at menarche calculated by logit was 12.14 y/o (95% CI 12.08 to 12.20). Mean ages obtained by recall were: for those who experienced menarche within the previous year 12.26 y/o (±1.14), between > 1-2 years before, 12.29 y (±1.22); between > 2-3 years before, 12.23 y/o (±1.27); and more than 3 years before, 11.55y/o (±1.24), p < 0.001. The age at menarche obtained by the recall method was similar for girls who menstruated within the previous 3 years (and approaches the age calculated by logit); when more than 3 years have passed, the recall bias was significant.

Image analysis of pubic bone for age estimation in a computed tomography sample.

PubMed

López-Alcaraz, Manuel; González, Pedro Manuel Garamendi; Aguilera, Inmaculada Alemán; López, Miguel Botella

2015-03-01

Radiology has demonstrated great utility for age estimation, but most of the studies are based on metrical and morphological methods in order to perform an identification profile. A simple image analysis-based method is presented, aimed to correlate the bony tissue ultrastructure with several variables obtained from the grey-level histogram (GLH) of computed tomography (CT) sagittal sections of the pubic symphysis surface and the pubic body, and relating them with age. The CT sample consisted of 169 hospital Digital Imaging and Communications in Medicine (DICOM) archives of known sex and age. The calculated multiple regression models showed a maximum R (2) of 0.533 for females and 0.726 for males, with a high intra- and inter-observer agreement. The method suggested is considered not only useful for performing an identification profile during virtopsy, but also for application in further studies in order to attach a quantitative correlation for tissue ultrastructure characteristics, without complex and expensive methods beyond image analysis.

Estimating age from the pubic symphysis: A new component-based system.

PubMed

Dudzik, Beatrix; Langley, Natalie R

2015-12-01

The os pubis is one of the most widely used areas of the skeleton for age estimation. Current pubic symphyseal aging methods for adults combine the morphology associated with the developmental changes that occur into the mid-30s with the degenerative changes that span the latter portion of the age spectrum. The most popular methods are phase-based; however, the definitions currently used to estimate age intervals may not be adequately defined and/or accurately understood by burgeoning researchers and seasoned practitioners alike. This study identifies patterns of growth and maturation in the pubic symphysis to derive more precise age estimates for individuals under 40 years of age. Emphasis is placed on young adults to provide more informative descriptions of epiphyseal changes associated with the final phases of skeletal maturation before degeneration commences. This study investigated macroscopic changes in forensically relevant modern U.S. samples of known age, sex, and ancestry from the Maricopa County Forensic Science Center in Phoenix, Arizona as well as donated individuals from the William M. Bass Forensic and Donated Collections at the University of Tennessee, Knoxville (n=237). Age-related traits at locations with ontogenetic and biomechanical relevance were broken into components and scored. The components included the pubic tubercle, the superior apex of the face, the ventral and dorsal demifaces, and the ventral and dorsal symphyseal margins. Transition analysis was applied to elucidate the transition ages between the morphological states of each component. The categorical scores and transition analysis ages were subjected to multinomial logistic regression and decision tree analysis to derive accurate age interval estimates. Results of these analyses were used to construct a decision tree-style flow chart for practitioner use. High inter-rater agreement of the individual component traits (linear weighted kappa values ≥0.665 for all traits in the

Correcting for initial Th in speleothems to obtain the age of calcite nucleation after a growth hiatus

NASA Astrophysics Data System (ADS)

Richards, D. A.; Nita, D. C.; Moseley, G. E.; Hoffmann, D. L.; Standish, C. D.; Smart, P. L.; Edwards, R.

2013-12-01

In addition to the many U-Th dated speleothem records (δ18O δ13C, trace elements) of past environmental change based on continuous phases of calcite growth, discontinuous records also provide important constraints for a wide range of past states of the Earth system, including sea levels, permafrost extent, regional aridity and local cave flooding. Chronological information about human activity or faunal evolution can also be obtained where calcite can be seen to overlie cave art or mammalian bones, for example. Among the important considerations when determining the U-Th age of calcite that nucleates on an exposed surface are (1) initial 230Th/232Th, which can be elevated and variable in some settings, and (2) growth rate and sub-sample density, where extrapolation is required. By way of example, we present sea level data based on U-Th ages of vadose speleothems (i.e. formed above the water table and distinct from 'phreatic' examples) from caves of the circum-Caribbean , where calcite growth was interrupted by rising sea levels and then reinitiated after regression. These estimates demand large corrections and derived sea level constraints are compared with alternative data from coral reef terraces, phreatic overgrowths on speleothems or indirect, proxy evidence from oxygen isotopes to constrain rates of ice volume growth. Flowstones from the Bahamas provide useful sea level constraints because they present the longest and most continuous records in such settings (a function of preservation potential in addition to hydrological routing) and also earliest growth post-emergence after sea level fall. We revisit estimates for sea level regression at the end of MIS 5 at ~ 80 ka (Richards et al, 1994; Lundberg and Ford, 1994) and make corrections for non-Bulk Earth initial Th contamination (230Th/232Th activity ratio > 10), based on isochron analysis of alternative stalagmites from the same settings and recent high resolution analysis. We also present new U-Th ages for

Service Lifetime Estimation of EPDM Rubber Based on Accelerated Aging Tests

NASA Astrophysics Data System (ADS)

Liu, Jie; Li, Xiangbo; Xu, Likun; He, Tao

2017-04-01

Service lifetime of ethylene propylene diene monomer (EPDM) rubber at room temperature (25 °C) was estimated based on accelerated aging tests. The study followed sealing stress loss on compressed cylinder samples by compression stress relaxation methods. The results showed that the cylinder samples of EPDM can quickly reach the physical relaxation equilibrium by using the over-compression method. The non-Arrhenius behavior occurred at the lowest aging temperature. A significant linear relationship was observed between compression set values and normalized stress decay results, and the relationship was not related to the ambient temperature of aging. It was estimated that the sealing stress loss in view of practical application would occur after around 86.8 years at 25 °C. The estimations at 25 °C based on the non-Arrhenius behavior were in agreement with compression set data from storage aging tests in natural environment.

The applicability of dental wear in age estimation for a modern American population.

PubMed

Faillace, Katie E; Bethard, Jonathan D; Marks, Murray K

2017-12-01

Though applied in bioarchaeology, dental wear is an underexplored age indicator in the biological anthropology of contemporary populations, although research has been conducted on dental attrition in forensic contexts (Kim et al., , Journal of Forensic Sciences, 45, 303; Prince et al., , Journal of Forensic Sciences, 53, 588; Yun et al., , Journal of Forensic Sciences, 52, 678). The purpose of this study is to apply and adapt existing techniques for age estimation based on dental wear to a modern American population, with the aim of producing accurate age range estimates for individuals from an industrialized context. Methodologies following Yun and Prince were applied to a random sample from the University of New Mexico (n = 583) and Universidade de Coimbra (n = 50) cast and skeletal collections. Analysis of variance (ANOVA) and linear regression analyses were conducted to examine the relationship between tooth wear scores and age. Application of both Yun et al. () and Prince et al. () methodologies resulted in inaccurate age estimates. Recalibrated sectioning points correctly classified individuals as over or under 50 years for 88% of the sample. Linear regression demonstrated 60% of age estimates fell within ±10 years of the actual age, and accuracy improved for individuals under 45 years, with 74% of predictions within ±10 years. This study demonstrates age estimation from dental wear is possible for modern populations, with comparable age intervals to other established methods. It provides a quantifiable method of seriation into "older" and "younger" adult categories, and provides more reliable age interval estimates than cranial sutures in instances where only the skull is available. © 2017 Wiley Periodicals, Inc.

A fully redundant double difference algorithm for obtaining minimum variance estimates from GPS observations

NASA Technical Reports Server (NTRS)

Melbourne, William G.

1986-01-01

In double differencing a regression system obtained from concurrent Global Positioning System (GPS) observation sequences, one either undersamples the system to avoid introducing colored measurement statistics, or one fully samples the system incurring the resulting non-diagonal covariance matrix for the differenced measurement errors. A suboptimal estimation result will be obtained in the undersampling case and will also be obtained in the fully sampled case unless the color noise statistics are taken into account. The latter approach requires a least squares weighting matrix derived from inversion of a non-diagonal covariance matrix for the differenced measurement errors instead of inversion of the customary diagonal one associated with white noise processes. Presented is the so-called fully redundant double differencing algorithm for generating a weighted double differenced regression system that yields equivalent estimation results, but features for certain cases a diagonal weighting matrix even though the differenced measurement error statistics are highly colored.

The Solar Twin Planet Search. III. The [Y/Mg] clock: estimating stellar ages of solar-type stars

NASA Astrophysics Data System (ADS)

Tucci Maia, M.; Ramírez, I.; Meléndez, J.; Bedell, M.; Bean, J. L.; Asplund, M.

2016-05-01

Context. Solar twins are stars with similar stellar (surface) parameters to the Sun that can have a wide range of ages. This provides an opportunity to analyze the variation of their chemical abundances with age. Nissen (2015, A&A, 579, A52) recently suggested that the abundances of the s-process element Y and the α-element Mg could be used to estimate stellar ages. Aims: This paper aims to determine with high precision the Y, Mg, and Fe abundances for a sample of 88 solar twins that span a broad age range (0.3-10.0 Gyr) and investigate their use for estimating ages. Methods: We obtained high-quality Magellan Inamori Kyocera Echelle (MIKE) spectra and determined Y and Mg abundances using equivalent widths and a line-by-line differential method within a 1D LTE framework. Stellar parameters and iron abundances were measured in Paper I of this series for all stars, but a few (three) required a small revision. Results: The [Y/Mg] ratio shows a strong correlation with age. It has a slope of -0.041 ± 0.001 dex/Gyr and a significance of 41σ. This is in excellent agreement with the relation first proposed by Nissen (2015). We found some outliers that turned out to be binaries where mass transfer may have enhanced the yttrium abundance. Given a precise measurement of [Y/Mg] with typical error of 0.02 dex in solar twins, our formula can be used to determine a stellar age with ~0.8 Gyr precision in the 0 to 10 Gyr range. Based on observations obtained at the Clay Magellan Telescopes at Las Campanas Observatory, Chile and at the 3.6 m Telescope at the La Silla ESO Observatory, Chile (program ID 188.C-0265).

Age estimation by modified Demirjian's method (2004) and its applicability in Tibetan young adults: A digital panoramic study.

PubMed

Bijjaragi, Shobha C; Sangle, Varsha A; Saraswathi, F K; Patil, Veerendra S; Ashwini Rani, S R; Bapure, Sunil K

2015-01-01

Estimation of the age is a procedure adopted by anthropologists, archeologists and forensic scientists. Different methods have been undertaken. However none of them meet the standards as Demirjian's method since 1973. Various researchers have applied this method, in both original and modified form (Chaillet and Demirjian in 2004) in different ethnic groups and the results obtained were not satisfactory. To determine the applicability and accuracy of modified Demirjian's method of dental age estimation (AE) in 8-18 year old Tibetan young adults to evaluate the interrelationship between dental and chronological age and the reliability between intra- and inter observer relationship. Clinical setting and computerized design. A total of 300 Tibetan young adults with an age range from 8 to 18 years were recruited in the study. Digital panoramic radiographs (DPRs) were evaluated as per the modified Demirjian's method (2004). Pearson correlation, paired t-test, linear regression analysis. Inter -and intraobserver reliability revealed a strong agreement. A positive and strong association was found between chronological age and estimated dental age (r = 0.839) with P < 0.01. Modified Demirjian method (2004) overestimated the age by 0.04 years (2.04 months)in Tibetan young adults. Results suggest that, the modified Demirjian method of AE is not suitable for Tibetan young adults. Further studies: With larger sample size and comparision with different methods of AE in a given population would be an interesting area for future research.

Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

USGS Publications Warehouse

Schwarz, L.K.; Runge, M.C.

2009-01-01

Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

Evaluation of the Applicability of Different Age Determination Methods for Estimating Age of the Endangered African Wild Dog (Lycaon Pictus).

PubMed

Mbizah, Moreangels M; Steenkamp, Gerhard; Groom, Rosemary J

2016-01-01

African wild dogs (Lycaon pictus) are endangered and their population continues to decline throughout their range. Given their conservation status, more research focused on their population dynamics, population growth and age specific mortality is needed and this requires reliable estimates of age and age of mortality. Various age determination methods from teeth and skull measurements have been applied in numerous studies and it is fundamental to test the validity of these methods and their applicability to different species. In this study we assessed the accuracy of estimating chronological age and age class of African wild dogs, from dental age measured by (i) counting cementum annuli (ii) pulp cavity/tooth width ratio, (iii) tooth wear (measured by tooth crown height) (iv) tooth wear (measured by tooth crown width/crown height ratio) (v) tooth weight and (vi) skull measurements (length, width and height). A sample of 29 African wild dog skulls, from opportunistically located carcasses was analysed. Linear and ordinal regression analysis was done to investigate the performance of each of the six age determination methods in predicting wild dog chronological age and age class. Counting cementum annuli was the most accurate method for estimating chronological age of wild dogs with a 79% predictive capacity, while pulp cavity/tooth width ratio was also a reliable method with a 68% predictive capacity. Counting cementum annuli and pulp cavity/tooth width ratio were again the most accurate methods for separating wild dogs into three age classes (6-24 months; 25-60 months and > 60 months), with a McFadden's Pseudo-R2 of 0.705 and 0.412 respectively. The use of the cementum annuli method is recommended when estimating age of wild dogs since it is the most reliable method. However, its use is limited as it requires tooth extraction and shipping, is time consuming and expensive, and is not applicable to living individuals. Pulp cavity/tooth width ratio is a moderately

Evaluation of the Applicability of Different Age Determination Methods for Estimating Age of the Endangered African Wild Dog (Lycaon Pictus)

PubMed Central

Steenkamp, Gerhard; Groom, Rosemary J.

2016-01-01

African wild dogs (Lycaon pictus) are endangered and their population continues to decline throughout their range. Given their conservation status, more research focused on their population dynamics, population growth and age specific mortality is needed and this requires reliable estimates of age and age of mortality. Various age determination methods from teeth and skull measurements have been applied in numerous studies and it is fundamental to test the validity of these methods and their applicability to different species. In this study we assessed the accuracy of estimating chronological age and age class of African wild dogs, from dental age measured by (i) counting cementum annuli (ii) pulp cavity/tooth width ratio, (iii) tooth wear (measured by tooth crown height) (iv) tooth wear (measured by tooth crown width/crown height ratio) (v) tooth weight and (vi) skull measurements (length, width and height). A sample of 29 African wild dog skulls, from opportunistically located carcasses was analysed. Linear and ordinal regression analysis was done to investigate the performance of each of the six age determination methods in predicting wild dog chronological age and age class. Counting cementum annuli was the most accurate method for estimating chronological age of wild dogs with a 79% predictive capacity, while pulp cavity/tooth width ratio was also a reliable method with a 68% predictive capacity. Counting cementum annuli and pulp cavity/tooth width ratio were again the most accurate methods for separating wild dogs into three age classes (6–24 months; 25–60 months and > 60 months), with a McFadden’s Pseudo-R2 of 0.705 and 0.412 respectively. The use of the cementum annuli method is recommended when estimating age of wild dogs since it is the most reliable method. However, its use is limited as it requires tooth extraction and shipping, is time consuming and expensive, and is not applicable to living individuals. Pulp cavity/tooth width ratio is a

Estimation of age at death from the pubic symphysis and the auricular surface of the ilium using a smoothing procedure.

PubMed

Martins, Rui; Oliveira, Paulo Eduardo; Schmitt, Aurore

2012-06-10

We discuss here the estimation of age at death from two indicators (pubic symphysis and the sacro-pelvic surface of the ilium) based on four different osteological series from Portugal, Great-Britain, South Africa or USA (European origin). These samples and the scoring system of the two indicators were used by Schmitt et al. (2002), applying the methodology proposed by Lucy et al. (1996). In the present work, the same data was processed using a modification of the empirical method proposed by Lucy et al. (2002). The various probability distributions are estimated from training data by using kernel density procedures and Jackknife methodology. Bayes's theorem is then used to produce the posterior distribution from which point and interval estimates may be made. This statistical approach reduces the bias of the estimates to less than 70% of what was obtained by the initial method. This reduction going up to 52% if knowledge of sex of the individual is available, and produces an age for all the individuals that improves age at death assessment. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Three-dimensional analysis of third molar development to estimate age of majority.

PubMed

Márquez-Ruiz, Ana Belén; Treviño-Tijerina, María Concepción; González-Herrera, Lucas; Sánchez, Belén; González-Ramírez, Amanda Rocío; Valenzuela, Aurora

2017-09-01

Third molars are one of the few biological markers available for age estimation in undocumented juveniles close the legal age of majority, assuming an age of 18years as the most frequent legal demarcation between child and adult status. To obtain more accurate visualization and evaluation of third molar mineralization patterns from computed tomography images, a new software application, DentaVol©, was developed. Third molar mineralization according to qualitative (Demirjian's maturational stage) and quantitative parameters (third molar volume) of dental development was assessed in multi-slice helical computed tomography images of both maxillary arches displayed by DentaVol© from 135 individuals (62 females and 73 males) aged between 14 and 23years. Intra- and inter-observer agreement values were remarkably high for both evaluation procedures and for all third molars. A linear correlation between third molar mineralization and chronological age was found, with third molar maturity occurring earlier in males than in females. Assessment of dental development with both procedures, by using DentaVol© software, can be considered a good indicator of age of majority (18years or older) in all third molars. Our results indicated that virtual computed tomography imaging can be considered a valid alternative to orthopantomography for evaluations of third molar mineralization, and therefore a complementary tool for determining the age of majority. Copyright © 2017 The Chartered Society of Forensic Sciences. Published by Elsevier B.V. All rights reserved.

Psychophysical estimation of speed discrimination. II. Aging effects

NASA Astrophysics Data System (ADS)

Raghuram, Aparna; Lakshminarayanan, Vasudevan; Khanna, Ritu

2005-10-01

We studied the effects of aging on a speed discrimination task using a pair of first-order drifting luminance gratings. Two reference speeds of 2 and 8 deg/s were presented at stimulus durations of 500 ms and 1000 ms. The choice of stimulus parameters, etc., was determined in preliminary experiments and described in Part I. Thresholds were estimated using a two-alternative-forced-choice staircase methodology. Data were collected from 16 younger subjects (mean age 24 years) and 17 older subjects (mean age 71 years). Results showed that thresholds for speed discrimination were higher for the older age group. This was especially true at stimulus duration of 500 ms for both slower and faster speeds. This could be attributed to differences in temporal integration of speed with age. Visual acuity and contrast sensitivity were not statistically observed to mediate age differences in the speed discrimination thresholds. Gender differences were observed in the older age group, with older women having higher thresholds.

Canine pulp ratios in estimating pensionable age in subjects with questionable documents of identification.

PubMed

Cameriere, Roberto; Ferrante, Luigi

2011-03-20

One of the most interesting reasons for needing to estimate age in adult subjects is to ascertain the age of a person of questionable pensionable age. This problem is becoming increasingly important in Europe, owing to the high number of immigrants without valid birth certificates. The aim of this paper is to evaluate the application of the apposition of secondary dentine of canines by the method of Cameriere et al. [10], in order to estimate the pensionable age of subjects without proper birth certificates. Periapical X-rays of 180 canines from 90 subjects aged between 50 and 79, 46 men and 44 women, were analysed. Estimated ages were used to test the medico-legal question as to whether an individual was older or younger than 65 years of age. In subjects under 65, age was correctly evaluated in 91% and 89% of individuals using maxillary and mandibular canines, respectively. In subjects over 65, of pensionable age, estimates were correct in 85% and 88% of cases, respectively. The proportion of individuals with correct classifications was 89% for both maxillary and mandibular canines taken together. In only four subjects, the results of maxillary and mandibular canines were discordant; in the other 86 subjects, the test of maxillary and mandibular canines yielded concordant results. Among the latter, the proportion of individuals who were really aged 65 years or older, and who were correctly estimated as such, was 94%, and the proportion of individuals younger than 65 years of age who were correctly estimated as such was 96%. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Secondary Forest Age and Tropical Forest Biomass Estimation Using TM

NASA Technical Reports Server (NTRS)

Nelson, R. F.; Kimes, D. S.; Salas, W. A.; Routhier, M.

1999-01-01

The age of secondary forests in the Amazon will become more critical with respect to the estimation of biomass and carbon budgets as tropical forest conversion continues. Multitemporal Thematic Mapper data were used to develop land cover histories for a 33,000 Square kM area near Ariquemes, Rondonia over a 7 year period from 1989-1995. The age of the secondary forest, a surrogate for the amount of biomass (or carbon) stored above-ground, was found to be unimportant in terms of biomass budget error rates in a forested TM scene which had undergone a 20% conversion to nonforest/agricultural cover types. In such a situation, the 80% of the scene still covered by primary forest accounted for over 98% of the scene biomass. The difference between secondary forest biomass estimates developed with and without age information were inconsequential relative to the estimate of biomass for the entire scene. However, in futuristic scenarios where all of the primary forest has been converted to agriculture and secondary forest (55% and 42% respectively), the ability to age secondary forest becomes critical. Depending on biomass accumulation rate assumptions, scene biomass budget errors on the order of -10% to +30% are likely if the age of the secondary forests are not taken into account. Single-date TM imagery cannot be used to accurately age secondary forests into single-year classes. A neural network utilizing TM band 2 and three TM spectral-texture measures (bands 3 and 5) predicted secondary forest age over a range of 0-7 years with an RMSE of 1.59 years and an R(Squared) (sub actual vs predicted) = 0.37. A proposal is made, based on a literature review, to use satellite imagery to identify general secondary forest age groups which, within group, exhibit relatively constant biomass accumulation rates.

A New Approach to Estimate the Age of the Earth and the Age of the Universe

NASA Astrophysics Data System (ADS)

Ben Salem, Kamel

2011-01-01

In a previous article, we proposed estimations for the age of the Universe and for the date of stabilization of its general structure on the basis of a given age of the Earth equal to 4.6 billion years. In the present article, we propose a new approach to estimate more accurately and at the same time, the age of the Earth and that of the Universe, starting from verse 4 of Sura 70 of the Qur'an. The procedure we followed and which is detailed in this article, should in our view, contribute to enlighten the debate on the question. We must add that our approach can in no case be considered as based on "concordism" or conjecture. Indeed, it rests on rigorous mathematical computations.

Some analytical models to estimate maternal age at birth using age-specific fertility rates.

PubMed

Pandey, A; Suchindran, C M

1995-01-01

"A class of analytical models to study the distribution of maternal age at different births from the data on age-specific fertility rates has been presented. Deriving the distributions and means of maternal age at birth of any specific order, final parity and at next-to-last birth, we have extended the approach to estimate parity progression ratios and the ultimate parity distribution of women in the population.... We illustrate computations of various components of the model expressions with the current fertility experiences of the United States for 1970." excerpt

Strategic Decision-Making Learning from Label Distributions: An Approach for Facial Age Estimation.

PubMed

Zhao, Wei; Wang, Han

2016-06-28

Nowadays, label distribution learning is among the state-of-the-art methodologies in facial age estimation. It takes the age of each facial image instance as a label distribution with a series of age labels rather than the single chronological age label that is commonly used. However, this methodology is deficient in its simple decision-making criterion: the final predicted age is only selected at the one with maximum description degree. In many cases, different age labels may have very similar description degrees. Consequently, blindly deciding the estimated age by virtue of the highest description degree would miss or neglect other valuable age labels that may contribute a lot to the final predicted age. In this paper, we propose a strategic decision-making label distribution learning algorithm (SDM-LDL) with a series of strategies specialized for different types of age label distribution. Experimental results from the most popular aging face database, FG-NET, show the superiority and validity of all the proposed strategic decision-making learning algorithms over the existing label distribution learning and other single-label learning algorithms for facial age estimation. The inner properties of SDM-LDL are further explored with more advantages.

Strategic Decision-Making Learning from Label Distributions: An Approach for Facial Age Estimation

PubMed Central

Zhao, Wei; Wang, Han

2016-01-01

Nowadays, label distribution learning is among the state-of-the-art methodologies in facial age estimation. It takes the age of each facial image instance as a label distribution with a series of age labels rather than the single chronological age label that is commonly used. However, this methodology is deficient in its simple decision-making criterion: the final predicted age is only selected at the one with maximum description degree. In many cases, different age labels may have very similar description degrees. Consequently, blindly deciding the estimated age by virtue of the highest description degree would miss or neglect other valuable age labels that may contribute a lot to the final predicted age. In this paper, we propose a strategic decision-making label distribution learning algorithm (SDM-LDL) with a series of strategies specialized for different types of age label distribution. Experimental results from the most popular aging face database, FG-NET, show the superiority and validity of all the proposed strategic decision-making learning algorithms over the existing label distribution learning and other single-label learning algorithms for facial age estimation. The inner properties of SDM-LDL are further explored with more advantages. PMID:27367691

Age estimation using level of eyebrow and eyelash whitening

PubMed Central

Kantarcı, Feride Aylin; Kantarcı, Muhammed Nabi; Bilgi, Sefer

2014-01-01

Background The aim of this study was to determine whether eyebrow and eyelash whitening is an effective parameter in age estimation. Material/Methods We evaluated 1545 patients. Age groups were 1–10, 11–20, 21–30, 31–40, 41–50, 51–60, 61–70, 71–80, and 81–90 years. Level of whitening was categorized as level 0: no whitening, level 1: 1–3 strands, level 2: 3–10 strands, level 3: 10 strands–2/3 whitening, level 4: >3/4 whitening. Results Mean age was 42.39±20.01. While there was no eyebrow whitening in 87% of the subjects, level 4 whitening of eyebrows was observed in 0,8% of the subjects. There was no eyelash whitening in 97,7% of the subjects and no level 4 eyelash whitening was detected in any subject. Men had significantly more level 1, 2, 3, and 4 eyebrow whitening compared with women. There was no gender difference in terms of eyelash whitening level. There was no eyebrow and eyelash whitening in subjects age 1–40 years; whitening began in the 41–50 years age group and increased with age in other groups. Mean age was 39.59±19.63 years in subjects with no eyebrow whitening; 59 years in level 1, 61 years in level 2, 63 years in level 3, and 69 years in level 4 eyebrow whitening. Mean age was 41.85±19.87 in subjects with no eyelash whitening; and 63.57±10.75 in those with whitening. Conclusions Particularly after 41–50 years of age, level of eyebrow and eyelash whitening may be among a useful age estimation parameter. PMID:24448310

Age estimation using cortical surface pattern combining thickness with curvatures

PubMed Central

Wang, Jieqiong; Li, Wenjing; Miao, Wen; Dai, Dai; Hua, Jing; He, Huiguang

2014-01-01

Brain development and healthy aging have been proved to follow a specific pattern, which, in turn, can be applied to help doctors diagnose mental diseases. In this paper, we design a cortical surface pattern (CSP) combining the cortical thickness with curvatures, which constructs an accurate human age estimation model with relevance vector regression. We test our model with two public databases. One is the IXI database (360 healthy subjects aging from 20 to 82 years old were selected), and the other is the INDI database (303 subjects aging from 7 to 22 years old were selected). The results show that our model can achieve as small as 4.57 years deviation in the IXI database and 1.38 years deviation in the INDI database. Furthermore, we employ this surface pattern to age groups classification, and get a remarkably high accuracy (97.77%) and a significantly high sensitivity/specificity (97.30%/98.10%). These results suggest that our designed CSP combining thickness with curvatures is stable and sensitive to brain development, and it is much more powerful than voxel-based morphometry used in previous methods for age estimation. PMID:24395657

So You Think You Look Young? Matching Older Adults' Subjective Ages with Age Estimations Provided by Younger, Middle-Aged, and Older Adults

ERIC Educational Resources Information Center

Kotter-Gruhn, Dana; Hess, Thomas M.

2012-01-01

Perceived age plays an important role in the context of age identity and social interactions. To examine how accurate individuals are in estimating how old they look and how old others are, younger, middle-aged, and older adults rated photographs of older target persons (for whom we had information about objective and subjective age) in terms of…

Use of NMR logging to obtain estimates of hydraulic conductivity in the High Plains aquifer, Nebraska, USA

USGS Publications Warehouse

Dlubac, Katherine; Knight, Rosemary; Song, Yi-Qiao; Bachman, Nate; Grau, Ben; Cannia, Jim; Williams, John

2013-01-01

Hydraulic conductivity (K) is one of the most important parameters of interest in groundwater applications because it quantifies the ease with which water can flow through an aquifer material. Hydraulic conductivity is typically measured by conducting aquifer tests or wellbore flow (WBF) logging. Of interest in our research is the use of proton nuclear magnetic resonance (NMR) logging to obtain information about water-filled porosity and pore space geometry, the combination of which can be used to estimate K. In this study, we acquired a suite of advanced geophysical logs, aquifer tests, WBF logs, and sidewall cores at the field site in Lexington, Nebraska, which is underlain by the High Plains aquifer. We first used two empirical equations developed for petroleum applications to predict K from NMR logging data: the Schlumberger Doll Research equation (KSDR) and the Timur-Coates equation (KT-C), with the standard empirical constants determined for consolidated materials. We upscaled our NMR-derived K estimates to the scale of the WBF-logging K(KWBF-logging) estimates for comparison. All the upscaled KT-C estimates were within an order of magnitude of KWBF-logging and all of the upscaled KSDR estimates were within 2 orders of magnitude of KWBF-logging. We optimized the fit between the upscaled NMR-derived K and KWBF-logging estimates to determine a set of site-specific empirical constants for the unconsolidated materials at our field site. We conclude that reliable estimates of K can be obtained from NMR logging data, thus providing an alternate method for obtaining estimates of K at high levels of vertical resolution.

A radiographic study estimating age of mandibular third molars by periodontal ligament visibility.

PubMed

Chaudhary, M A; Liversidge, H M

2017-12-01

Visibility of the periodontal ligament of mandibular third molars (M3) has been suggested as a method to estimate age. To assess the accuracy of this method and compare the visibility of the periodontal ligament in the left M3 with the right M3. The sample was archived panoramic dental radiographs of 163 individuals (75 males, 88 females, age 16-53 years) with mature M3's. Reliability was assessed using Kappa. Accuracy was assessed by subtracting chronological age from estimated age for males and females. Stages were cross-tabulated against age stages younger than and at least 18 and 21 years of age. Stages were compared in the left M3 and right M3. Analysis showed excellent intra-observer reliability. Mean difference between estimated and chronological ages was 7.21 years (SD 5.16) for left M3 and 7.69 (SD 6.08) for right M3 in males and 6.87 (SD 5.83) for left M3 and 8.61 (SD 6.58) for right M3 in females. Minimum ages of stages 0 to 2 were younger than previously reported, despite a small sample of individuals younger than 18. The left and right M3 stage differed in 46% of the 85 individuals with readings from both side and estimated age differed from -10.5 to 12.2 years between left and right. Accuracy of this method was between 6 and 8 years with an error of 5 to 6 years. The number of individuals with mature M3 apices younger than 18 years was small. The stage of visibility of the periodontal ligament differed between left and right in almost half of our sample with both teeth present. Our findings question the use of this method to estimate age or to discriminate between age younger and at least 18 years.

Demirjian approach of dental age estimation: Abridged for operator ease.

PubMed

Jain, Vanshika; Kapoor, Priyanka; Miglani, Ragini

2016-01-01

Present times have seen an alarming increase in incidence of crimes by juveniles and of mass destruction that Highlight the preponderance of individual age estimation. Of the numerous techniques employed for age assessment, dental age estimation (DAE) and its correlation with chronological age (CA) have been of great significance in the recent past. Demirjian system, considered as gold standard in DAE is a simple and convenient method for DAE, though,, although, referring to multiple tables make it cumbersome and less eco friendly due to excessive paper load. The present study was aimed to develop a comprehensive chart (DAEcc) inclusive of all Demirjian tables and developmental stages of teeth and also to as well as to test the operator ease of 50 undergraduate dental students in performing DAE using this chart. The study was performed in two stages, wherein the first stage was aimed at formulation of the comprehensive chart (DAE CC ) which included pictorial representation of calcification stages, the Federation Dentaire Internationale notation of the teeth, and the corresponding scores for each stage with a concluding column at the end to enter the total score. The second stage assessed the applicability of the ease of DAE by DAE CC , whereby fifty 2 nd year BDS students were asked to trace the calcification stages of the seven permanent left mandibular teeth on a panorex, identify the correct stage, assign the corresponding score, and to calculate the total score for subsequent dental age assessment. showed that average time taken by the students for tracing seven mandibular teeth was 5 min and for assessment of dental age was 7 min. The total time taken for DAE was approximately 12 min, thus making the procedure less time consuming. Hence, this study proposes the use of DAEcc for age estimation due to ease in comprehension and execution of Demirjian system.

Estimating stage-specific daily survival probabilities of nests when nest age is unknown

USGS Publications Warehouse

Stanley, T.R.

2004-01-01

Estimation of daily survival probabilities of nests is common in studies of avian populations. Since the introduction of Mayfield's (1961, 1975) estimator, numerous models have been developed to relax Mayfield's assumptions and account for biologically important sources of variation. Stanley (2000) presented a model for estimating stage-specific (e.g. incubation stage, nestling stage) daily survival probabilities of nests that conditions on “nest type” and requires that nests be aged when they are found. Because aging nests typically requires handling the eggs, there may be situations where nests can not or should not be aged and the Stanley (2000) model will be inapplicable. Here, I present a model for estimating stage-specific daily survival probabilities that conditions on nest stage for active nests, thereby obviating the need to age nests when they are found. Specifically, I derive the maximum likelihood function for the model, evaluate the model's performance using Monte Carlo simulations, and provide software for estimating parameters (along with an example). For sample sizes as low as 50 nests, bias was small and confidence interval coverage was close to the nominal rate, especially when a reduced-parameter model was used for estimation.

Estimation of the aging grade of T91 steel by laser-induced breakdown spectroscopy coupled with support vector machines

NASA Astrophysics Data System (ADS)

Lu, Shengzi; Dong, Meirong; Huang, Jianwei; Li, Wenbing; Lu, Jidong; Li, Jun

2018-02-01

T91 steel is a representative martensitic heat-resistant steel widely used in high temperature compression components of industrial equipment. During the service period, the operation safety and the service life of the equipment will be affected by the change of structure and mechanical properties of the steel components, which is called material aging. In order to develop a rapid in-situ aging estimation technology of high temperature compression components surface, laser-induced breakdown spectroscopy (LIBS) coupled with support vector machine (SVM) was employed in this paper. The spectral characteristics of 10 T91 steel specimens with different aging grades were analyzed. Line intensities and the line intensity ratios (ionic/atomic and alloying element/matrix element) that indicate the change of metallographic structure were used to establish SVM models, and the results using different variable sets were compared. The model was optimized by comparing different pulse number for practical effectiveness, and the robustness of the model was investigated in dealing with the inhomogeneity of steel composition. The study results show that the estimation model obtained the best performance using line intensities and line intensity ratios averaged from 31st-60th laser pulses as input variables. The estimation accuracy of validation set was greatly improved from 75.8% to 95.3%. In addition, the model showed the outstanding capacity for handling the fluctuations of spectral signals between measuring-points (spots), which indicated that the aging estimation based on a few measuring-points is feasible. The studies presented here demonstrate that the LIBS coupled with SVM is a new useful technique for the aging estimation of steel, and would be well-suited for fast safety assessment in industrial field.

Gestational age estimates from singleton births conceived using assisted reproductive technology.

PubMed

Callaghan, William M; Schieve, Laura A; Dietz, Patricia M

2007-09-01

Information on gestational age for public health research and surveillance in the US is usually obtained from vital records and is primarily based on the first day of the woman's last menstrual period (LMP). However, using LMP as a marker of conception is subject to a variety of errors and results in misclassification of gestational age. Pregnancies conceived through assisted reproductive technology (ART) are unique in that the estimates of gestational age are not based on the LMP, but on the date when fertilisation actually occurred, and thus most gestational age errors are likely to be due to errors introduced in recording and data entry. The purpose of this paper was to examine the birthweight distribution by gestational age for ART singleton livebirths reported to a national ART surveillance system. Gestational age was categorised as 20-27, 28-31, 32-36 and 37-44 weeks; birthweight distributions were plotted for each category. The distributions of very-low-birthweight (VLBW; <1500 g), moderately low-birthweight (1500-2499 g) and normal-birthweight infants for each gestational week were examined. At both 20-27 and 28-31 weeks, there was an extended right tail to the distribution and a small second mode. At 32-36 weeks, there were long tails in either direction and at 37-44 weeks, an extended tail to the left. There was a high proportion of VLBW infants at low gestational ages and a decreasing proportion of VLBW infants with increasing gestational age. However, there was also a fairly constant proportion of normal-birthweight infants at every gestational age below 34 weeks, which suggested misclassification of gestational age. Approximately 12% of ART births classified as 28-31 weeks' gestation had a birthweight in the second mode of the birthweight distribution compared with approximately 29% in national vital statistics data. Even when the birthweight and dates of conception and birth are known, questions remain regarding the residual amount of

Estimating brain age using high-resolution pattern recognition: Younger brains in long-term meditation practitioners.

PubMed

Luders, Eileen; Cherbuin, Nicolas; Gaser, Christian

2016-07-01

Normal aging is known to be accompanied by loss of brain substance. The present study was designed to examine whether the practice of meditation is associated with a reduced brain age. Specific focus was directed at age fifty and beyond, as mid-life is a time when aging processes are known to become more prominent. We applied a recently developed machine learning algorithm trained to identify anatomical correlates of age in the brain translating those into one single score: the BrainAGE index (in years). Using this validated approach based on high-dimensional pattern recognition, we re-analyzed a large sample of 50 long-term meditators and 50 control subjects estimating and comparing their brain ages. We observed that, at age fifty, brains of meditators were estimated to be 7.5years younger than those of controls. In addition, we examined if the brain age estimates change with increasing age. While brain age estimates varied only little in controls, significant changes were detected in meditators: for every additional year over fifty, meditators' brains were estimated to be an additional 1month and 22days younger than their chronological age. Altogether, these findings seem to suggest that meditation is beneficial for brain preservation, effectively protecting against age-related atrophy with a consistently slower rate of brain aging throughout life. Copyright © 2016 Elsevier Inc. All rights reserved.

Absolute and estimated values of macular pigment optical density in young and aged Asian participants with or without age-related macular degeneration.

PubMed

Ozawa, Yoko; Shigeno, Yuta; Nagai, Norihiro; Suzuki, Misa; Kurihara, Toshihide; Minami, Sakiko; Hirano, Eri; Shinoda, Hajime; Kobayashi, Saori; Tsubota, Kazuo

2017-08-29

Lutein and zeaxanthin are suggested micronutrient supplements to prevent the progression of age-related macular degeneration (AMD), a leading cause of blindness worldwide. To monitor the levels of lutein/zeaxanthin in the macula, macular pigment optical density (MPOD) is measured. A commercially available device (MPSII®, Elektron Technology, Switzerland), using technology based on heterochromatic flicker photometry, can measure both absolute and estimated values of MPOD. However, whether the estimated value is applicable to Asian individuals and/or AMD patients remains to be determined. The absolute and estimated values of MPOD were measured using the MPSII® device in 77 participants with a best-corrected visual acuity (BCVA) > 0.099 (logMAR score). The studied eyes included 17 young (20-29 years) healthy, 26 aged (>50 years) healthy, 18 aged and AMD-fellow, and 16 aged AMD eyes. The mean BCVA among the groups were not significantly different. Both absolute and estimated values were measurable in all eyes of young healthy group. However, absolute values were measurable in only 57.7%, 66.7%, and 43.8%, of the aged healthy, AMD-fellow, and AMD groups, respectively, and 56.7% of the eyes included in the 3 aged groups. In contrast, the estimated value was measurable in 84.6%, 88.9% and 93.8% of the groups, respectively, and 88.3% of eyes in the pooled aged group. The estimated value was correlated with absolute value in individuals from all groups by Spearman's correlation coefficient analyses (young healthy: R 2  = 0.885, P = 0.0001; aged healthy: R 2  = 0.765, P = 0.001; AMD-fellow: R 2  = 0.851, P = 0.0001; and AMD: R 2  = 0.860, P = 0.013). Using the estimated value, significantly lower MPOD values were found in aged AMD-related eyes, which included both AMD-fellow and AMD eyes, compared with aged healthy eyes by Student's t-test (P = 0.02). Absolute, in contrast to estimated, value was measurable in a limited number of aged participants

Variation between last-menstrual-period and clinical estimates of gestational age in vital records.

PubMed

Qin, Cheng; Hsia, Jason; Berg, Cynthia J

2008-03-15

An accurate assessment of gestational age is vital to population-based research and surveillance in maternal and infant health. However, the quality of gestational age measurements derived from birth certificates has been in question. Using the 2002 US public-use natality file, the authors examined the agreement between estimates of gestational age based on the last menstrual period (LMP) and clinical estimates in vital records across durations of gestation and US states and explored reasons for disagreement. Agreement between the LMP and the clinical estimate of gestational age varied substantially across gestations and among states. Preterm births were more likely than term births to have disagreement between the two estimates. Maternal age, maternal education, initiation of prenatal care, order of livebirth, and use of ultrasound had significant independent effects on the disagreement between the two measures, regardless of gestational age, but these factors made little difference in the magnitude of gestational age group differences. Information available on birth certificates was not sufficient to understand this disparity. The lowest agreement between the LMP and the clinical estimate was observed among preterm infants born at 28-36 weeks' gestation, who accounted for more than 90% of total preterm births. This finding deserves particular attention and further investigation.

Probabilities and statistics for backscatter estimates obtained by a scatterometer with applications to new scatterometer design data

NASA Technical Reports Server (NTRS)

Pierson, Willard J., Jr.

1989-01-01

The values of the Normalized Radar Backscattering Cross Section (NRCS), sigma (o), obtained by a scatterometer are random variables whose variance is a known function of the expected value. The probability density function can be obtained from the normal distribution. Models for the expected value obtain it as a function of the properties of the waves on the ocean and the winds that generated the waves. Point estimates of the expected value were found from various statistics given the parameters that define the probability density function for each value. Random intervals were derived with a preassigned probability of containing that value. A statistical test to determine whether or not successive values of sigma (o) are truly independent was derived. The maximum likelihood estimates for wind speed and direction were found, given a model for backscatter as a function of the properties of the waves on the ocean. These estimates are biased as a result of the terms in the equation that involve natural logarithms, and calculations of the point estimates of the maximum likelihood values are used to show that the contributions of the logarithmic terms are negligible and that the terms can be omitted.

Relationship between sweat chloride, sodium, and age in clinically obtained samples.

PubMed

Traeger, Nadav; Shi, Qiuhu; Dozor, Allen J

2014-01-01

The relationship between sweat electrolytes and age is uncertain, as is the value of measuring sodium or the chloride:sodium ratio. 13,785 sweat tests performed over 23 years at one center through the Macroduct collection in clinically obtained samples were analyzed. Sweat chloride tended to decrease over the first year of life, slowly increase until the fourth decade, then either level off or slightly decrease. In children, sweat sodium overlapped between those with positive and negative sweat tests, but not in adults. If the sweat test was positive, there was a higher likelihood of having a chloride:sodium ratio >1, but most subjects with a ratio >1 did not have CF. Sweat chloride and sodium vary with age. Measurement of sweat sodium did not add discriminatory value. The proportion of subjects with a chloride:sodium ratio >1, with or without CF, varied greatly between age ranges. © 2013. Published by Elsevier B.V. on behalf of European Cystic Fibrosis Society. All rights reserved.

Age estimation of bloodstains using smartphones and digital image analysis.

PubMed

Thanakiatkrai, Phuvadol; Yaodam, Alisa; Kitpipit, Thitika

2013-12-10

Recent studies on bloodstains have focused on determining the time since deposition of bloodstains, which can provide useful temporal information to forensic investigations. This study is the first to use smartphone cameras in combination with a truly low-cost illumination system as a tool to estimate the age of bloodstains. Bloodstains were deposited on various substrates and photographed with a smartphone camera. Three smartphones (Samsung Galaxy S Plus, Apple iPhone 4, and Apple iPad 2) were compared. The environmental effects - temperature, humidity, light exposure, and anticoagulant - on the bloodstain age estimation process were explored. The color values from the digital images were extracted and correlated with time since deposition. Magenta had the highest correlation (R(2)=0.966) and was used in subsequent experiments. The Samsung Galaxy S Plus was the most suitable smartphone as its magenta decreased exponentially with increasing time and had highest repeatability (low variation within and between pictures). The quantifiable color change observed is consistent with well-established hemoglobin denaturation process. Using a statistical classification technique called Random Forests™, we could predict bloodstain age accurately up to 42 days with an error rate of 12%. Additionally, the age of forty blind stains were all correctly predicted, and 83% of mock casework samples were correctly classified. No within- and between-person variations were observed (p>0.05), while smartphone camera, temperature, humidity, and substrate color influenced the age determination process in different ways. Our technique provides a cheap, rapid, easy-to-use, and truly portable alternative to more complicated analysis using specialized equipment, e.g. spectroscopy and HPLC. No training is necessary with our method, and we envision a smartphone application that could take user inputs of environmental factors and provide an accurate estimate of bloodstain age. Copyright © 2013

Radiological pitfalls of age estimation in adopted children: a case report.

PubMed

Gibelli, D; De Angelis, D; Cattaneo, C

2015-04-01

Age estimation has a relevant importance in assessing adopted children, also in cases where the age of the minor seems unquestioned, since pathological conditions may radically alter bodily growth. This may lead to an incorrect age evaluation, with consequent social and psychological problems linked to an inadequate collocation in public school. This study aims at exposing a case report concerning age estimation for a newly adopted child from Cambodia; previous clinical documentation reported information suggesting possible malnutrition, which was verified by the observation of a general disalignment of bone and dental structures. This example shows the importance of a thorough forensic evaluation of adopted children from other countries in order to verify the possible environmental modification of physiological growth even where it seems not to be needed, and represents a caveat for clinical and social personnel dealing with adoption procedures.

Improving size estimates of open animal populations by incorporating information on age

USGS Publications Warehouse

Manly, Bryan F.J.; McDonald, Trent L.; Amstrup, Steven C.; Regehr, Eric V.

2003-01-01

Around the world, a great deal of effort is expended each year to estimate the sizes of wild animal populations. Unfortunately, population size has proven to be one of the most intractable parameters to estimate. The capture-recapture estimation models most commonly used (of the Jolly-Seber type) are complicated and require numerous, sometimes questionable, assumptions. The derived estimates usually have large variances and lack consistency over time. In capture–recapture studies of long-lived animals, the ages of captured animals can often be determined with great accuracy and relative ease. We show how to incorporate age information into size estimates for open populations, where the size changes through births, deaths, immigration, and emigration. The proposed method allows more precise estimates of population size than the usual models, and it can provide these estimates from two sample occasions rather than the three usually required. Moreover, this method does not require specialized programs for capture-recapture data; researchers can derive their estimates using the logistic regression module in any standard statistical package.

Setting the light conditions for measuring root transparency for age-at-death estimation methods.

PubMed

Adserias-Garriga, Joe; Nogué-Navarro, Laia; Zapico, Sara C; Ubelaker, Douglas H

2018-03-01

Age-at-death estimation is one of the main goals in forensic identification, being an essential parameter to determine the biological profile, narrowing the possibility of identification in cases involving missing persons and unidentified bodies. The study of dental tissues has been long considered as a proper tool for age estimation with several age estimation methods based on them. Dental age estimation methods can be divided into three categories: tooth formation and development, post-formation changes, and histological changes. While tooth formation and growth changes are important for fetal and infant consideration, when the end of dental and skeletal growth is achieved, post-formation or biochemical changes can be applied. Lamendin et al. in J Forensic Sci 37:1373-1379, (1992) developed an adult age estimation method based on root transparency and periodontal recession. The regression formula demonstrated its accuracy of use for 40 to 70-year-old individuals. Later on, Prince and Ubelaker in J Forensic Sci 47(1):107-116, (2002) evaluated the effects of ancestry and sex and incorporated root height into the equation, developing four new regression formulas for males and females of African and European ancestry. Even though root transparency is a key element in the method, the conditions for measuring this element have not been established. The aim of the present study is to set the light conditions measured in lumens that offer greater accuracy when applying the Lamendin et al. method modified by Prince and Ubelaker. The results must be also taken into account in the application of other age estimation methodologies using root transparency to estimate age-at-death.

Defining and Estimating Healthy Aging in Spain: A Cross-sectional Study.

PubMed

Rodriguez-Laso, Angel; McLaughlin, Sara J; Urdaneta, Elena; Yanguas, Javier

2018-03-19

Using an operational continuum of healthy aging developed by U.S. researchers, we sought to estimate the prevalence of healthy aging among older Spaniards, inform the development of a definition of healthy aging in Spain, and foster cross-national research on healthy aging. The ELES pilot study is a nationwide, cross-sectional survey of community-dwelling Spaniards 50 years and older. The prevalence of healthy aging was calculated for the 65 and over population using varying definitions. To evaluate their validity, we examined the association of healthy aging with the 8 foot up & go test, quality of life scores and self-perceived health using multiple linear and logistic regression. The estimated prevalence of healthy aging varied across the operational continuum, from 4.5% to 49.2%. Prevalence figures were greater for men and those aged 65 to 79 years and were higher than in the United States. Predicted mean physical performance scores were similar for 3 of the 4 definitions, suggesting that stringent definitions of healthy aging offer little advantage over a more moderate one. Similar to U.S. researchers, we recommend a definition of healthy aging that incorporates measures of functional health and limiting disease as opposed to definitions requiring the absence of all disease in studies designed to assess the effect of policy initiatives on healthy aging.

Random regression models on Legendre polynomials to estimate genetic parameters for weights from birth to adult age in Canchim cattle.

PubMed

Baldi, F; Albuquerque, L G; Alencar, M M

2010-08-01

The objective of this work was to estimate covariance functions for direct and maternal genetic effects, animal and maternal permanent environmental effects, and subsequently, to derive relevant genetic parameters for growth traits in Canchim cattle. Data comprised 49,011 weight records on 2435 females from birth to adult age. The model of analysis included fixed effects of contemporary groups (year and month of birth and at weighing) and age of dam as quadratic covariable. Mean trends were taken into account by a cubic regression on orthogonal polynomials of animal age. Residual variances were allowed to vary and were modelled by a step function with 1, 4 or 11 classes based on animal's age. The model fitting four classes of residual variances was the best. A total of 12 random regression models from second to seventh order were used to model direct and maternal genetic effects, animal and maternal permanent environmental effects. The model with direct and maternal genetic effects, animal and maternal permanent environmental effects fitted by quadric, cubic, quintic and linear Legendre polynomials, respectively, was the most adequate to describe the covariance structure of the data. Estimates of direct and maternal heritability obtained by multi-trait (seven traits) and random regression models were very similar. Selection for higher weight at any age, especially after weaning, will produce an increase in mature cow weight. The possibility to modify the growth curve in Canchim cattle to obtain animals with rapid growth at early ages and moderate to low mature cow weight is limited.

A revised burial dose estimation procedure for optical dating of youngand modern-age sediments

USGS Publications Warehouse

Arnold, L.J.; Roberts, R.G.; Galbraith, R.F.; DeLong, S.B.

2009-01-01

The presence of genuinely zero-age or near-zero-age grains in modern-age and very young samples poses a problem for many existing burial dose estimation procedures used in optical (optically stimulated luminescence, OSL) dating. This difficulty currently necessitates consideration of relatively simplistic and statistically inferior age models. In this study, we investigate the potential for using modified versions of the statistical age models of Galbraith et??al. [Galbraith, R.F., Roberts, R.G., Laslett, G.M., Yoshida, H., Olley, J.M., 1999. Optical dating of single and multiple grains of quartz from Jinmium rock shelter, northern Australia: Part I, experimental design and statistical models. Archaeometry 41, 339-364.] to provide reliable equivalent dose (De) estimates for young and modern-age samples that display negative, zero or near-zero De estimates. For this purpose, we have revised the original versions of the central and minimum age models, which are based on log-transformed De values, so that they can be applied to un-logged De estimates and their associated absolute standard errors. The suitability of these 'un-logged' age models is tested using a series of known-age fluvial samples deposited within two arroyo systems from the American Southwest. The un-logged age models provide accurate burial doses and final OSL ages for roughly three-quarters of the total number of samples considered in this study. Sensitivity tests reveal that the un-logged versions of the central and minimum age models are capable of producing accurate burial dose estimates for modern-age and very young (<350??yr) fluvial samples that contain (i) more than 20% of well-bleached grains in their De distributions, or (ii) smaller sub-populations of well-bleached grains for which the De values are known with high precision. Our results indicate that the original (log-transformed) versions of the central and minimum age models are still preferable for most routine dating applications

A Novel Physiology-Based Mathematical Model to Estimate Red Blood Cell Lifespan in Different Human Age Groups.

PubMed

An, Guohua; Widness, John A; Mock, Donald M; Veng-Pedersen, Peter

2016-09-01

Direct measurement of red blood cell (RBC) survival in humans has improved from the original accurate but limited differential agglutination technique to the current reliable, safe, and accurate biotin method. Despite this, all of these methods are time consuming and require blood sampling over several months to determine the RBC lifespan. For situations in which RBC survival information must be obtained quickly, these methods are not suitable. With the exception of adults and infants, RBC survival has not been extensively investigated in other age groups. To address this need, we developed a novel, physiology-based mathematical model that quickly estimates RBC lifespan in healthy individuals at any age. The model is based on the assumption that the total number of RBC recirculations during the lifespan of each RBC (denoted by N max) is relatively constant for all age groups. The model was initially validated using the data from our prior infant and adult biotin-labeled red blood cell studies and then extended to the other age groups. The model generated the following estimated RBC lifespans in 2-year-old, 5-year-old, 8-year-old, and 10-year-old children: 62, 74, 82, and 86 days, respectively. We speculate that this model has useful clinical applications. For example, HbA1c testing is not reliable in identifying children with diabetes because HbA1c is directly affected by RBC lifespan. Because our model can estimate RBC lifespan in children at any age, corrections to HbA1c values based on the model-generated RBC lifespan could improve diabetes diagnosis as well as therapy in children.

[Forensic age estimation in juveniles and young adults: Reducing the range of scatter in age diagnosis by combining different methods].

PubMed

Schmidt, Sven; Schramm, Danilo; Ribbecke, Sebastian; Schulz, Ronald; Wittschieber, Daniel; Olze, Andreas; Vieth, Volker; Ramsthaler, H Frank; Pfischel, Klaus; Pfeiffer, Heidi; Geserick, Gunther; Schmeling, Andreas

2016-01-01

The dramatic rise in the number of refugees entering Germany means that age estimation for juveniles and young adults whose age is unclear but relevant to legal and official procedures has become more important than ever. Until now, whether and to what extent the combination of methods recommended by the Study Group on Forensic Age Diagnostics has resulted in a reduction of the range of scatter of the summarized age diagnosis has been unclear. Hand skeletal age, third molar mineralization stage and ossification stage of the medial clavicular epiphyses were determined for 307 individuals aged between 10 and 29 at time of death on whom autopsies were performed at the Institutes of Legal Medicine in Berlin, Frankfurt am Main and Hamburg between 2001 and 2011. To measure the range of scatter, linear regression analysis was used to calculate the standard error of estimate for each of the above methods individually and in combination. It was found that combining the above methods led to a reduction in the range of scatter. Due to various limitations of the study, the statistical parameters determined cannot, however, be used for age estimation practice.

Estimated maximal and current brain volume predict cognitive ability in old age

PubMed Central

Royle, Natalie A.; Booth, Tom; Valdés Hernández, Maria C.; Penke, Lars; Murray, Catherine; Gow, Alan J.; Maniega, Susana Muñoz; Starr, John; Bastin, Mark E.; Deary, Ian J.; Wardlaw, Joanna M.

2013-01-01

Brain tissue deterioration is a significant contributor to lower cognitive ability in later life; however, few studies have appropriate data to establish how much influence prior brain volume and prior cognitive performance have on this association. We investigated the associations between structural brain imaging biomarkers, including an estimate of maximal brain volume, and detailed measures of cognitive ability at age 73 years in a large (N = 620), generally healthy, community-dwelling population. Cognitive ability data were available from age 11 years. We found positive associations (r) between general cognitive ability and estimated brain volume in youth (male, 0.28; females, 0.12), and in measured brain volume in later life (males, 0.27; females, 0.26). Our findings show that cognitive ability in youth is a strong predictor of estimated prior and measured current brain volume in old age but that these effects were the same for both white and gray matter. As 1 of the largest studies of associations between brain volume and cognitive ability with normal aging, this work contributes to the wider understanding of how some early-life factors influence cognitive aging. PMID:23850342

Estimated maximal and current brain volume predict cognitive ability in old age.

PubMed

Royle, Natalie A; Booth, Tom; Valdés Hernández, Maria C; Penke, Lars; Murray, Catherine; Gow, Alan J; Maniega, Susana Muñoz; Starr, John; Bastin, Mark E; Deary, Ian J; Wardlaw, Joanna M

2013-12-01

Brain tissue deterioration is a significant contributor to lower cognitive ability in later life; however, few studies have appropriate data to establish how much influence prior brain volume and prior cognitive performance have on this association. We investigated the associations between structural brain imaging biomarkers, including an estimate of maximal brain volume, and detailed measures of cognitive ability at age 73 years in a large (N = 620), generally healthy, community-dwelling population. Cognitive ability data were available from age 11 years. We found positive associations (r) between general cognitive ability and estimated brain volume in youth (male, 0.28; females, 0.12), and in measured brain volume in later life (males, 0.27; females, 0.26). Our findings show that cognitive ability in youth is a strong predictor of estimated prior and measured current brain volume in old age but that these effects were the same for both white and gray matter. As 1 of the largest studies of associations between brain volume and cognitive ability with normal aging, this work contributes to the wider understanding of how some early-life factors influence cognitive aging. Copyright © 2013 Elsevier Inc. All rights reserved.

Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

PubMed Central

Verochana, Karune; Prapayasatok, Sangsom; Mahasantipiya, Phattaranant May; Korwanich, Narumanas

2016-01-01

Purpose This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. Materials and Methods The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Results Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. Conclusion The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age. PMID:27051633

Accuracy of an equation for estimating age from mandibular third molar development in a Thai population.

PubMed

Verochana, Karune; Prapayasatok, Sangsom; Janhom, Apirum; Mahasantipiya, Phattaranant May; Korwanich, Narumanas

2016-03-01

This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

Validity of gestational age estimates by last menstrual period and neonatal examination compared to ultrasound in Vietnam.

PubMed

Deputy, Nicholas P; Nguyen, Phuong H; Pham, Hoa; Nguyen, Son; Neufeld, Lynnette; Martorell, Reynaldo; Ramakrishnan, Usha

2017-01-11

Accurate estimation of gestational age is important for both clinical and public health purposes. Estimates of gestational age using fetal ultrasound measurements are considered most accurate but are frequently unavailable in low- and middle-income countries. The objective of this study was to assess the validity of last menstrual period and Farr neonatal examination estimates of gestational age, compared to ultrasound estimates, in a large cohort of women in Vietnam. Data for this analysis come from a randomized, placebo-controlled micronutrient supplementation trial in Vietnam. We analyzed 912 women with ultrasound and prospectively-collected last menstrual period estimates of gestational age and 685 women with ultrasound and Farr estimates of gestational age. We used the Wilcoxon signed rank sum test to assess differences in gestational age estimated by last menstrual period or Farr examination compared to ultrasound and computed the intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC) to quantify agreement between methods. We computed the Kappa coefficient (κ) to quantify agreement in preterm, term and post-term classification. The median gestational age estimated by ultrasound was 273.9 days. Gestational age was slightly overestimated by last menstrual period (median 276.0 days, P < 0.001) and more greatly overestimated by Farr examination (median 286.7 days, P < 0.001). Gestational age estimates by last menstrual period and ultrasound were moderately correlated (ICC = 0.78) and concordant (CCC = 0.63), whereas gestational age estimates by Farr examination and ultrasound were weakly correlated (ICC = 0.26) and concordant (CCC = 0.05). Last menstrual period and ultrasound estimates of gestational age were within ± 14 days for 88.4% of women; Farr and ultrasound estimates were within ± 14 days for 55.8% of women. Last menstrual period and ultrasound estimates of gestational age had higher

Batch Effect Confounding Leads to Strong Bias in Performance Estimates Obtained by Cross-Validation

PubMed Central

Delorenzi, Mauro

2014-01-01

Background With the large amount of biological data that is currently publicly available, many investigators combine multiple data sets to increase the sample size and potentially also the power of their analyses. However, technical differences (“batch effects”) as well as differences in sample composition between the data sets may significantly affect the ability to draw generalizable conclusions from such studies. Focus The current study focuses on the construction of classifiers, and the use of cross-validation to estimate their performance. In particular, we investigate the impact of batch effects and differences in sample composition between batches on the accuracy of the classification performance estimate obtained via cross-validation. The focus on estimation bias is a main difference compared to previous studies, which have mostly focused on the predictive performance and how it relates to the presence of batch effects. Data We work on simulated data sets. To have realistic intensity distributions, we use real gene expression data as the basis for our simulation. Random samples from this expression matrix are selected and assigned to group 1 (e.g., ‘control’) or group 2 (e.g., ‘treated’). We introduce batch effects and select some features to be differentially expressed between the two groups. We consider several scenarios for our study, most importantly different levels of confounding between groups and batch effects. Methods We focus on well-known classifiers: logistic regression, Support Vector Machines (SVM), k-nearest neighbors (kNN) and Random Forests (RF). Feature selection is performed with the Wilcoxon test or the lasso. Parameter tuning and feature selection, as well as the estimation of the prediction performance of each classifier, is performed within a nested cross-validation scheme. The estimated classification performance is then compared to what is obtained when applying the classifier to independent data. PMID:24967636

Skeletal age estimation for forensic purposes: A comparison of GP, TW2 and TW3 methods on an Italian sample.

PubMed

Pinchi, Vilma; De Luca, Federica; Ricciardi, Federico; Focardi, Martina; Piredda, Valentina; Mazzeo, Elena; Norelli, Gian-Aristide

2014-05-01

Paediatricians, radiologists, anthropologists and medico-legal specialists are often called as experts in order to provide age estimation (AE) for forensic purposes. The literature recommends performing the X-rays of the left hand and wrist (HW-XR) for skeletal age estimation. The method most frequently employed is the Greulich and Pyle (GP) method. In addition, the so-called bone-specific techniques are also applied including the method of Tanner Whitehouse (TW) in the latest versions TW2 and TW3. To compare skeletal age and chronological age in a large sample of children and adolescents using GP, TW2 and TW3 methods in order to establish which of these is the most reliable for forensic purposes. The sample consisted of 307 HW-XRs of Italian children or adolescents, 145 females and 162 males aged between 6 and 20 years. The radiographies were scored according to the GP, TW2RUS and TW3RUS methods by one investigator. The results' reliability was assessed using intraclass correlation coefficient. Wilcoxon signed-rank test and Student t-test were performed to search for significant differences between skeletal and chronological ages. The distributions of the differences between estimated and chronological age, by means of boxplots, show how median differences for TW3 and GP methods are generally very close to 0. Hypothesis tests' results were obtained, with respect to the sex, both for the entire group of individuals and people grouped by age. Results show no significant differences among estimated and chronological age for TW3 and, to a lesser extent, GP. The TW2 proved to be the worst of the three methods. Our results support the conclusion that the TW2 method is not reliable for AE for forensic purpose. The GP and TW3 methods have proved to be reliable in males. For females, the best method was found to be TW3. When performing forensic age estimation in subjects around 14 years of age, it could be advisable to use and associate the TW3 and GP methods. Copyright �

Age estimation of archaeological remains using amino acid racemization in dental enamel: a comparison of morphological, biochemical, and known ages-at-death.

PubMed

Griffin, R C; Chamberlain, A T; Hotz, G; Penkman, K E H; Collins, M J

2009-10-01

The poor accuracy of most current methods for estimating age-at-death in adult human skeletal remains is among the key problems facing palaeodemography. In forensic science, this problem has been solved for unburnt remains by the development of a chemical method for age estimation, using amino acid racemization in collagen extracted from dentine. Previous application of racemization methods to archaeological material has proven problematic. This study presents the application to archaeological human remains of a new age estimation method utilizing amino acid racemization in a potentially closed system-the dental enamel. The amino acid composition and extent of racemization in enamel from two Medieval cemeteries (Newcastle Blackgate and Grantham, England) and from a documented age-at-death sample from a 19th century cemetery (Spitalfriedhof St Johann, Switzerland) were determined. Alterations in the amino acid composition were detected in all populations, indicating that diagenetic change had taken place. However, in the Medieval populations, these changes did not appear to have substantially affected the relationship between racemization and age-at-death, with a strong relationship being retained between aspartic acid racemization and the morphological age estimates. In contrast, there was a poor relationship between racemization and age in the post-medieval documented age-at-death population from Switzerland. This appears to be due to leaching of amino acids post-mortem, indicating that enamel is not functioning as a perfectly closed system. Isolation of amino acids from a fraction of enamel which is less susceptible to leaching may improve the success of amino acid racemization for archaeological age estimation.

Forensic age estimation by morphometric analysis of the manubrium from 3D MR images.

PubMed

Martínez Vera, Naira P; Höller, Johannes; Widek, Thomas; Neumayer, Bernhard; Ehammer, Thomas; Urschler, Martin

2017-08-01

Forensic age estimation research based on skeletal structures focuses on patterns of growth and development using different bones. In this work, our aim was to study growth-related evolution of the manubrium in living adolescents and young adults using magnetic resonance imaging (MRI), which is an image acquisition modality that does not involve ionizing radiation. In a first step, individual manubrium and subject features were correlated with age, which confirmed a statistically significant change of manubrium volume (M vol :p<0.01, R 2 ¯=0.50) and surface area (M sur :p<0.01, R 2 ¯=0.53) for the studied age range. Additionally, shapes of the manubria were for the first time investigated using principal component analysis. The decomposition of the data in principal components allowed to analyse the contribution of each component to total shape variation. With 13 principal components, ∼96% of shape variation could be described (M shp :p<0.01, R 2 ¯=0.60). Multiple linear regression analysis modelled the relationship between the statistically best correlated variables and age. Models including manubrium shape, volume or surface area divided by the height of the subject (Y∼M shp M sur /S h :p<0.01, R 2 ¯=0.71; Y∼M shp M vol /S h :p<0.01, R 2 ¯=0.72) presented a standard error of estimate of two years. In order to estimate the accuracy of these two manubrium-based age estimation models, cross validation experiments predicting age on held-out test sets were performed. Median absolute difference of predicted and known chronological age was 1.18 years for the best performing model (Y∼M shp M sur /S h :p<0.01, R p 2 =0.67). In conclusion, despite limitations in determining legal majority age, manubrium morphometry analysis presented statistically significant results for skeletal age estimation, which indicates that this bone structure may be considered as a new candidate in multi-factorial MRI-based age estimation. Copyright © 2017 Elsevier B.V. All rights

Estimating age from recapture data: integrating incremental growth measures with ancillary data to infer age-at-length

USGS Publications Warehouse

Eaton, Mitchell J.; Link, William A.

2011-01-01

Estimating the age of individuals in wild populations can be of fundamental importance for answering ecological questions, modeling population demographics, and managing exploited or threatened species. Significant effort has been devoted to determining age through the use of growth annuli, secondary physical characteristics related to age, and growth models. Many species, however, either do not exhibit physical characteristics useful for independent age validation or are too rare to justify sacrificing a large number of individuals to establish the relationship between size and age. Length-at-age models are well represented in the fisheries and other wildlife management literature. Many of these models overlook variation in growth rates of individuals and consider growth parameters as population parameters. More recent models have taken advantage of hierarchical structuring of parameters and Bayesian inference methods to allow for variation among individuals as functions of environmental covariates or individual-specific random effects. Here, we describe hierarchical models in which growth curves vary as individual-specific stochastic processes, and we show how these models can be fit using capture–recapture data for animals of unknown age along with data for animals of known age. We combine these independent data sources in a Bayesian analysis, distinguishing natural variation (among and within individuals) from measurement error. We illustrate using data for African dwarf crocodiles, comparing von Bertalanffy and logistic growth models. The analysis provides the means of predicting crocodile age, given a single measurement of head length. The von Bertalanffy was much better supported than the logistic growth model and predicted that dwarf crocodiles grow from 19.4 cm total length at birth to 32.9 cm in the first year and 45.3 cm by the end of their second year. Based on the minimum size of females observed with hatchlings, reproductive maturity was estimated

Estimation of Correlation between Chronological Age, Skeletal Age and Dental Age in Children- A Cross-sectional Study

PubMed Central

Macha, Madhulika; Lamba, Bharti; Muthineni, Sridhar; Margana, Pratap Gowd Jai Shankar; Chitoori, Prasad

2017-01-01

Introduction In the modern era, identification and determination of age is imperative for diversity of reasons that include disputed birth records, premature delivery, legal issues and for validation of birth certificate for school admissions, adoption, marriage, job and immigration. Several growth assessment parameters like bone age, dental age and the combination of both have been applied for different population with variable outcomes. It has been well documented that the chronological age does not necessarily correlate with the maturational status of a child. Hence, efforts were made to determine a child’s developmental age by using dental age (calcification of teeth) and skeletal age (skeletal maturation). Aim The present study was aimed to correlate the chronological age, dental age and skeletal age in children from Southeastern region of Andhra Pradesh, India. Materials and Methods Out of the total 900 screened children, only 100 subjects between age groups of 6-14 years with a mean age of 11.3±2.63 for males and 10.77±2.24 for females were selected for the study. Dental age was calculated by Demirjian method and skeletal age by modified Middle Phalanx of left hand third finger (MP3) method. Pearson’s and Spearman’s correlation tests were done to estimate the correlation between chronological, dental and skeletal ages among study population. Results There was a significant positive correlation between chronological age, dental age and all stages of MP3 among males. Similar results were observed in females, except for a non-significant moderate correlation between chronological age and dental age in the H stage of the MP3 region. Conclusion The results of the present study revealed correlation with statistical significance (p<0.05) between chronological, dental and skeletal ages among all the subjects (48 males and 52 females) and females attained maturity earlier than males in the present study population. PMID:29207822

Estimation of Correlation between Chronological Age, Skeletal Age and Dental Age in Children- A Cross-sectional Study.

PubMed

Macha, Madhulika; Lamba, Bharti; Avula, Jogendra Sai Sankar; Muthineni, Sridhar; Margana, Pratap Gowd Jai Shankar; Chitoori, Prasad

2017-09-01

In the modern era, identification and determination of age is imperative for diversity of reasons that include disputed birth records, premature delivery, legal issues and for validation of birth certificate for school admissions, adoption, marriage, job and immigration. Several growth assessment parameters like bone age, dental age and the combination of both have been applied for different population with variable outcomes. It has been well documented that the chronological age does not necessarily correlate with the maturational status of a child. Hence, efforts were made to determine a child's developmental age by using dental age (calcification of teeth) and skeletal age (skeletal maturation). The present study was aimed to correlate the chronological age, dental age and skeletal age in children from Southeastern region of Andhra Pradesh, India. Out of the total 900 screened children, only 100 subjects between age groups of 6-14 years with a mean age of 11.3±2.63 for males and 10.77±2.24 for females were selected for the study. Dental age was calculated by Demirjian method and skeletal age by modified Middle Phalanx of left hand third finger (MP3) method. Pearson's and Spearman's correlation tests were done to estimate the correlation between chronological, dental and skeletal ages among study population. There was a significant positive correlation between chronological age, dental age and all stages of MP3 among males. Similar results were observed in females, except for a non-significant moderate correlation between chronological age and dental age in the H stage of the MP3 region. The results of the present study revealed correlation with statistical significance (p<0.05) between chronological, dental and skeletal ages among all the subjects (48 males and 52 females) and females attained maturity earlier than males in the present study population.

Development of modern human subadult age and sex estimation standards using multi-slice computed tomography images from medical examiner's offices

NASA Astrophysics Data System (ADS)

Stock, Michala K.; Stull, Kyra E.; Garvin, Heather M.; Klales, Alexandra R.

2016-10-01

Forensic anthropologists are routinely asked to estimate a biological profile (i.e., age, sex, ancestry and stature) from a set of unidentified remains. In contrast to the abundance of collections and techniques associated with adult skeletons, there is a paucity of modern, documented subadult skeletal material, which limits the creation and validation of appropriate forensic standards. Many are forced to use antiquated methods derived from small sample sizes, which given documented secular changes in the growth and development of children, are not appropriate for application in the medico-legal setting. Therefore, the aim of this project is to use multi-slice computed tomography (MSCT) data from a large, diverse sample of modern subadults to develop new methods to estimate subadult age and sex for practical forensic applications. The research sample will consist of over 1,500 full-body MSCT scans of modern subadult individuals (aged birth to 20 years) obtained from two U.S. medical examiner's offices. Statistical analysis of epiphyseal union scores, long bone osteometrics, and os coxae landmark data will be used to develop modern subadult age and sex estimation standards. This project will result in a database of information gathered from the MSCT scans, as well as the creation of modern, statistically rigorous standards for skeletal age and sex estimation in subadults. Furthermore, the research and methods developed in this project will be applicable to dry bone specimens, MSCT scans, and radiographic images, thus providing both tools and continued access to data for forensic practitioners in a variety of settings.

A Protocol for Aging Anurans Using Skeletochronology

USGS Publications Warehouse

McCreary, Brome; Pearl, Christopher A.; Adams, Michael J.

2008-01-01

Age distribution information can be an important part of understanding the biology of any population. Age estimates collected from the annual growth rings found in tooth and bone cross sections, often referred to as Lines of Arrested Growth (LAGs), have been used in the study of various animals. In this manual, we describe in detail all necessary steps required to obtain estimates of age from anuran bone cross sections via skeletochronological assessment. We include comprehensive descriptions of how to fix and decalcify toe specimens (phalanges), process a phalange prior to embedding, embed the phalange in paraffin, section the phalange using a microtome, stain and mount the cross sections of the phalange and read the LAGs to obtain age estimates.

Forensic dental age estimation by measuring root dentin translucency area using a new digital technique.

PubMed

Acharya, Ashith B

2014-05-01

Dentin translucency measurement is an easy yet relatively accurate approach to postmortem age estimation. Translucency area represents a two-dimensional change and may reflect age variations better than length. Manually measuring area is challenging and this paper proposes a new digital method using commercially available computer hardware and software. Area and length were measured on 100 tooth sections (age range, 19-82 years) of 250 μm thickness. Regression analysis revealed lower standard error of estimate and higher correlation with age for length than for area (R = 0.62 vs. 0.60). However, test of regression formulae on a control sample (n = 33, 21-85 years) showed smaller mean absolute difference (8.3 vs. 8.8 years) and greater frequency of smaller errors (73% vs. 67% age estimates ≤ ± 10 years) for area than for length. These suggest that digital area measurements of root translucency may be used as an alternative to length in forensic age estimation. © 2014 American Academy of Forensic Sciences.

Age estimation by dentin translucency measurement using digital method: An institutional study

PubMed Central

Gupta, Shalini; Chandra, Akhilesh; Agnihotri, Archana; Gupta, Om Prakash; Maurya, Niharika

2017-01-01

Aims: The aims of the present study were to measure translucency on sectioned teeth using available computer hardware and software, to correlate dimensions of root dentin translucency with age, and to assess whether translucency is reliable for age estimation. Materials and Methods: A pilot study was done on 62 freshly extracted single-rooted permanent teeth from 62 different individuals (35 males and 27 females) and their 250 μm thick sections were prepared by micromotor, carborundum disks, and Arkansas stone. Each tooth section was scanned and the images were opened in the Adobe Photoshop software. Measurement of root dentin translucency (TD length) was done on the scanned image by placing two guides (A and B) along the x-axis of ABFO NO. 2 scale. Unpaired t-test, regression analysis, and Pearson correlation coefficient were used as statistical tools. Results: A linear relationship was observed between TD length and age in the regression analysis. The Pearson correlation analysis showed that there was positive correlation (r = 0.52, P = 0.0001) between TD length and age. However, no significant (P > 0.05) difference was observed in the TD length between male (8.44 ± 2.92 mm) and female (7.80 ± 2.79 mm) samples. Conclusion: Translucency of the root dentin increases with age and it can be used as a reliable parameter for the age estimation. The method used here to digitally select and measure translucent root dentin is more refined, better correlated to age, and produce superior age estimation. PMID:28584476

Age estimation of the Deccan Traps from the North American apparent polar wander path

NASA Technical Reports Server (NTRS)

Stoddard, Paul R.; Jurdy, Donna M.

1988-01-01

It has recently been proposed that flood basalt events, such as the eruption of the Deccan Traps, have been responsible for mass extinctions. To test this hypothesis, accurate estimations of the ages and duration of these events are needed. In the case of the Deccan Traps, however, neither age nor duration of emplacement is well constrianed; measured ages range from 40 to more than 80 Myr, and estimates of duration range from less than 1 to 67 Myr. To make an independent age determination, paleomagnetic and sea-floor-spreading data are used, and the associated errors are estimated. The Deccan paleomagnetic pole is compared with the reference apparent polar wander path of North America by rotating the positions of the paleomagnetic pole for the Deccan Traps to the reference path for a range of assumed ages. Uncertainties in the apparent polar wander path, Deccan paleopole position, and errors resulting from the plate reconstruction are estimated. It is suggested that 83-70 Myr is the most likely time of extrusion of these volcanic rocks.

Estimation of gestational age from hand and foot length.

PubMed

Kumar, G P; Kumar, U K

1994-01-01

Abortion, foeticide and infanticide have been practised from time immemorial by both primitive and civilized societies. Establishing the precise duration of gestation is an important point in the total medical evidentiary picture of infanticide. In this study, an attempt has been made to establish the gestational age of the foetus using foot and hand length. This study will be of help in establishing the gestational age when the foetus is fragmented. Results obtained were significant in establishing the gestational age.

Gene expression during blow fly development: improving the precision of age estimates in forensic entomology.

PubMed

Tarone, Aaron M; Foran, David R

2011-01-01

Forensic entomologists use size and developmental stage to estimate blow fly age, and from those, a postmortem interval. Since such estimates are generally accurate but often lack precision, particularly in the older developmental stages, alternative aging methods would be advantageous. Presented here is a means of incorporating developmentally regulated gene expression levels into traditional stage and size data, with a goal of more precisely estimating developmental age of immature Lucilia sericata. Generalized additive models of development showed improved statistical support compared to models that did not include gene expression data, resulting in an increase in estimate precision, especially for postfeeding third instars and pupae. The models were then used to make blind estimates of development for 86 immature L. sericata raised on rat carcasses. Overall, inclusion of gene expression data resulted in increased precision in aging blow flies. © 2010 American Academy of Forensic Sciences.

Precision of hard structures used to estimate age of mountain Whitefish (Prosopium williamsoni)

USGS Publications Warehouse

Watkins, Carson J.; Ross, Tyler J.; Hardy, Ryan S.; Quist, Michael C.

2015-01-01

The mountain whitefish (Prosopium williamsoni) is a widely distributed salmonid in western North America that has decreased in abundance over portions of its distribution due to anthropogenic disturbances. In this investigation, we examined precision of age estimates derived from scales, pectoral fin rays, and sagittal otoliths from 167 mountain whitefish. Otoliths and pectoral fin rays were mounted in epoxy and cross-sectioned before examination. Scales were pressed onto acetate slides and resulting impressions were examined. Between-reader precision (i.e., between 2 readers), between-reader variability, and reader confidence ratings were compared among hard structures. Coefficient of variation (CV) in age estimates was lowest and percentage of exact agreement (PA-0) was highest for scales (CV = 5.9; PA-0 = 70%) compared to pectoral fin rays (CV =11.0; PA-0 = 58%) and otoliths (CV = 12.3; PA-0 = 55%). Median confidence ratings were significantly different (P ≤ 0.05) among all structures, with scales having the highest median confidence. Reader confidence decreased with fish age for scales and pectoral fin rays, but reader confidence increased with fish age for otoliths. In general, age estimates were more precise and reader confidence was higher for scales compared to pectoral fin rays and otoliths. This research will help fisheries biologists in selecting the most appropriate hard structure to use for future age and growth studies on mountain whitefish. In turn, selection of the most precise hard structure will lead to better estimates of dynamic rate functions.

Age estimation standards for a Western Australian population using the coronal pulp cavity index.

PubMed

Karkhanis, Shalmira; Mack, Peter; Franklin, Daniel

2013-09-10

Age estimation is a vital aspect in creating a biological profile and aids investigators by narrowing down potentially matching identities from the available pool. In addition to routine casework, in the present global political scenario, age estimation in living individuals is required in cases of refugees, asylum seekers, human trafficking and to ascertain age of criminal responsibility. Thus robust methods that are simple, non-invasive and ethically viable are required. The aim of the present study is, therefore, to test the reliability and applicability of the coronal pulp cavity index method, for the purpose of developing age estimation standards for an adult Western Australian population. A total of 450 orthopantomograms (220 females and 230 males) of Australian individuals were analyzed. Crown and coronal pulp chamber heights were measured in the mandibular left and right premolars, and the first and second molars. These measurements were then used to calculate the tooth coronal index. Data was analyzed using paired sample t-tests to assess bilateral asymmetry followed by simple linear and multiple regressions to develop age estimation models. The most accurate age estimation based on simple linear regression model was with mandibular right first molar (SEE ±8.271 years). Multiple regression models improved age prediction accuracy considerably and the most accurate model was with bilateral first and second molars (SEE ±6.692 years). This study represents the first investigation of this method in a Western Australian population and our results indicate that the method is suitable for forensic application. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Age estimation of living Indian individuals based on aspartic acid racemization from tooth biopsy specimen

PubMed Central

Rastogi, Manu; Logani, Ajay; Shah, Naseem; Kumar, Abhishek; Arora, Saurabh

2017-01-01

Background: Age estimation in living individuals is imperative to amicably settle civil and criminal disputes. A biochemical method based on amino acid racemization was evaluated for age estimation of living Indian individuals. Design: Caries-free maxillary/mandibular premolar teeth (n = 90) were collected from participants with age proof documents and divided into predefined nine age groups. Materials and Methods: Dentine biopsy from the labial aspect of the tooth crown was taken with an indigenously developed microtrephine. The samples were processed and subjected to gas chromatography. Dextrorotatory:levorotatory ratios were calculated, and a regression equation was formulated. Results: Across all age groups, an error of 0 ± 4 years between protein racemization age and chronological age was observed. Conclusion: Aspartic acid racemization from dentine biopsy samples could be a viable and accurate technique for age estimation of living individuals who have attained a state of skeletal maturity. PMID:29263613

Using dual-domain advective-transport simulation to reconcile multiple-tracer ages and estimate dual-porosity transport parameters

NASA Astrophysics Data System (ADS)

Sanford, Ward E.; Niel Plummer, L.; Casile, Gerolamo; Busenberg, Ed; Nelms, David L.; Schlosser, Peter

2017-06-01

Dual-domain transport is an alternative conceptual and mathematical paradigm to advection-dispersion for describing the movement of dissolved constituents in groundwater. Here we test the use of a dual-domain algorithm combined with advective pathline tracking to help reconcile environmental tracer concentrations measured in springs within the Shenandoah Valley, USA. The approach also allows for the estimation of the three dual-domain parameters: mobile porosity, immobile porosity, and a domain exchange rate constant. Concentrations of CFC-113, SF6, 3H, and 3He were measured at 28 springs emanating from carbonate rocks. The different tracers give three different mean composite piston-flow ages for all the springs that vary from 5 to 18 years. Here we compare four algorithms that interpret the tracer concentrations in terms of groundwater age: piston flow, old-fraction mixing, advective-flow path modeling, and dual-domain modeling. Whereas the second two algorithms made slight improvements over piston flow at reconciling the disparate piston-flow age estimates, the dual-domain algorithm gave a very marked improvement. Optimal values for the three transport parameters were also obtained, although the immobile porosity value was not well constrained. Parameter correlation and sensitivities were calculated to help quantify the uncertainty. Although some correlation exists between the three parameters being estimated, a watershed simulation of a pollutant breakthrough to a local stream illustrates that the estimated transport parameters can still substantially help to constrain and predict the nature and timing of solute transport. The combined use of multiple environmental tracers with this dual-domain approach could be applicable in a wide variety of fractured-rock settings.

Bias correction of nutritional status estimates when reported age is used for calculating WHO indicators in children under five years of age.

PubMed

Quezada, Amado D; García-Guerra, Armando; Escobar, Leticia

2016-06-01

To assess the performance of a simple correction method for nutritional status estimates in children under five years of age when exact age is not available from the data. The proposed method was based on the assumption of symmetry of age distributions within a given month of age and validated in a large population-based survey sample of Mexican preschool children. The main distributional assumption was consistent with the data. All prevalence estimates derived from the correction method showed no statistically significant bias. In contrast, failing to correct attained age resulted in an underestimation of stunting in general and an overestimation of overweight or obesity among the youngest. The proposed method performed remarkably well in terms of bias correction of estimates and could be easily applied in situations in which either birth or interview dates are not available from the data.

Human dental age estimation combining third molar(s) development and tooth morphological age predictors.

PubMed

Thevissen, P W; Galiti, D; Willems, G

2012-11-01

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23 years, 25 gender-specific radiographs were collected within each age category of 1 year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by Köhler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals' left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R (2)) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6 % R² increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15-23 year) should only be based on third molar development.

Age estimates for the late quaternary high sea-stands

NASA Astrophysics Data System (ADS)

Smart, Peter L.; Richards, David A.

A database of more than 300 published alpha-counted uranium-series ages has been compiled for coral reef terraces formed by Late Pleistocene high sea-stands. The database was screened to eliminate unreliable age estimates ( {230Th }/{232Th } < 20, calcite > 5%) and those without quoted without quoted errors, and a distributed error frequency curve was produced. This curve can be considered as a finite mixture model comprising k component normal distributions each with a weighting α. By using an expectation maximising algorithm, the mean and standard deviation of the component distributions, each corresponding to a high sea level event, were estimated. Eight high sea-stands with mean and standard deviations of 129.0 ± 33.0, 123.0 ± 13.0, 102.5 ± 2.0, 81.5 ± 5.0, 61.5 ± 6.0, 50.0 ± 1.0, 40.5 ± 5.0 and 33.0 ± 2.5 ka were resolved. The standard deviations are generally larger than the values quoted for individual age estimates. Whilst this may be due to diagenetic effects, especially for the older corals, it is argued that in many cases geological evidence clearly indicates that the high stands are multiple events, often not resolvable at sites with low rates of uplift. The uranium-series dated coral-reef terrace chronology shows good agreement with independent chronologies derived for Antarctic ice cores, although the resolution for the latter is better. Agreement with orbitally-tuned deep-sea core records is also good, but it is argued that Isotope Stage 5e is not a single event, as recorded in the cores, but a multiple event spanning some 12 ka. The much earlier age for Isotope Stage 5e given by Winograd et al. (1988) is not supported by the coral reef data, but further mass-spectrometric uranium-series dating is needed to permit better chronological resolution.

Porosity estimation of aged mortar using a micromechanical model.

PubMed

Hernández, M G; Anaya, J J; Sanchez, T; Segura, I

2006-12-22

Degradation of concrete structures located in high humidity atmospheres or under flowing water is a very important problem. In this study, a method for ultrasonic non-destructive characterization in aged mortar is presented. The proposed method makes a prediction of the behaviour of aged mortar accomplished with a three phase micromechanical model using ultrasonic measurements. Aging mortar was accelerated by immersing the probes in ammonium nitrate solution. Both destructive and non-destructive characterization of mortar was performed. Destructive tests of porosity were performed using a vacuum saturation method and non-destructive characterization was carried out using ultrasonic velocities. Aging experiments show that mortar degradation not only involves a porosity increase, but also microstructural changes in the cement matrix. Experimental results show that the estimated porosity using the proposed non-destructive methodology had a comparable performance to classical destructive techniques.

Estimating Small-area Populations by Age and Sex Using Spatial Interpolation and Statistical Inference Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qai, Qiang; Rushton, Gerald; Bhaduri, Budhendra L

The objective of this research is to compute population estimates by age and sex for small areas whose boundaries are different from those for which the population counts were made. In our approach, population surfaces and age-sex proportion surfaces are separately estimated. Age-sex population estimates for small areas and their confidence intervals are then computed using a binomial model with the two surfaces as inputs. The approach was implemented for Iowa using a 90 m resolution population grid (LandScan USA) and U.S. Census 2000 population. Three spatial interpolation methods, the areal weighting (AW) method, the ordinary kriging (OK) method, andmore » a modification of the pycnophylactic method, were used on Census Tract populations to estimate the age-sex proportion surfaces. To verify the model, age-sex population estimates were computed for paired Block Groups that straddled Census Tracts and therefore were spatially misaligned with them. The pycnophylactic method and the OK method were more accurate than the AW method. The approach is general and can be used to estimate subgroup-count types of variables from information in existing administrative areas for custom-defined areas used as the spatial basis of support in other applications.« less

Age estimation by canines' pulp/tooth ratio in an Iranian population using digital panoramic radiography.

PubMed

Dehghani, Mahdieh; Shadkam, Elaheh; Ahrari, Farzaneh; Dehghani, Mahboobe

2018-04-01

Age estimation in adults is an important issue in forensic science. This study aimed to estimate the chronological age of Iranians by means of pulp/tooth area ratio (AR) of canines in digital panoramic radiographs. The sample consisted of panoramic radiographs of 271 male and female subjects aged 16-64 years. The pulp/tooth area ratio (AR) of upper and lower canines was calculated by AutoCAD software. Data were subjected to correlation and regression analysis. There was a significant and inverse correlation between age and pulp/tooth area ratio of upper and lower canines (r=-0.794 for upper canine and r=-0.282 for lower canine; p-value<0.001). Linear regression equations were derived separately for upper, lower and both canines. The mean difference between actual and estimated age using upper canine was 6.07±1.7. The results showed that the pulp/tooth area ratios of canines are a reliable method for age estimation in Iranians. The pulp/tooth area ratio of upper canine was better correlated with chronological age than that of lower canine. Copyright © 2018 Elsevier B.V. All rights reserved.

Size at emergence improves accuracy of age estimates in forensically-useful beetle Creophilus maxillosus L. (Staphylinidae).

PubMed

Matuszewski, Szymon; Frątczak-Łagiewska, Katarzyna

2018-02-05

Insects colonizing human or animal cadavers may be used to estimate post-mortem interval (PMI) usually by aging larvae or pupae sampled on a crime scene. The accuracy of insect age estimates in a forensic context is reduced by large intraspecific variation in insect development time. Here we test the concept that insect size at emergence may be used to predict insect physiological age and accordingly to improve the accuracy of age estimates in forensic entomology. Using results of laboratory study on development of forensically-useful beetle Creophilus maxillosus (Linnaeus, 1758) (Staphylinidae) we demonstrate that its physiological age at emergence [i.e. thermal summation value (K) needed for emergence] fall with an increase of beetle size. In the validation study it was found that K estimated based on the adult insect size was significantly closer to the true K as compared to K from the general thermal summation model. Using beetle length at emergence as a predictor variable and male or female specific model regressing K against beetle length gave the most accurate predictions of age. These results demonstrate that size of C. maxillosus at emergence improves accuracy of age estimates in a forensic context.

Demirjian's method in the estimation of age: A study on human third molars

PubMed Central

Lewis, Amitha J.; Boaz, Karen; Nagesh, K. R; Srikant, N; Gupta, Neha; Nandita, K. P; Manaktala, Nidhi

2015-01-01

Aim: The primary aim of the following study is to estimate the chronological age based on the stages of third molar development following the eight stages (A to H) method of Demirjian et al. (along with two modifications-Orhan) and secondary aim is to compare third molar development with sex and age. Materials and Methods: The sample consisted of 115 orthopantomograms from South Indian subjects with known chronological age and gender. Multiple regression analysis was performed with chronological age as the dependable variable and third molar root development as independent variable. All the statistical analysis was performed using the SPSS 11.0 package (IBM ® Corporation). Results: Statistically no significant differences were found in third molar development between males and females. Depending on the available number of wisdom teeth in an individual, R2 varied for males from 0.21 to 0.48 and for females from 0.16 to 0.38. New equations were derived for estimating the chronological age. Conclusion: The chronological age of a South Indian individual between 14 and 22 years may be estimated based on the regression formulae. However, additional studies with a larger study population must be conducted to meet the need for population-based information on third molar development. PMID:26005306

Demirjian's method in the estimation of age: A study on human third molars.

PubMed

Lewis, Amitha J; Boaz, Karen; Nagesh, K R; Srikant, N; Gupta, Neha; Nandita, K P; Manaktala, Nidhi

2015-01-01

The primary aim of the following study is to estimate the chronological age based on the stages of third molar development following the eight stages (A to H) method of Demirjian et al. (along with two modifications-Orhan) and secondary aim is to compare third molar development with sex and age. The sample consisted of 115 orthopantomograms from South Indian subjects with known chronological age and gender. Multiple regression analysis was performed with chronological age as the dependable variable and third molar root development as independent variable. All the statistical analysis was performed using the SPSS 11.0 package (IBM ® Corporation). Statistically no significant differences were found in third molar development between males and females. Depending on the available number of wisdom teeth in an individual, R (2) varied for males from 0.21 to 0.48 and for females from 0.16 to 0.38. New equations were derived for estimating the chronological age. The chronological age of a South Indian individual between 14 and 22 years may be estimated based on the regression formulae. However, additional studies with a larger study population must be conducted to meet the need for population-based information on third molar development.

Age estimation based on aspartic acid racemization in elastin from the yellow ligaments.

PubMed

Ritz-Timme, S; Laumeier, I; Collins, M

2003-04-01

The yellow ligaments of the spine are characterized by an exceptionally high content of elastin, a protein with a proved longevity in several human tissues. This unique biochemical composition suggested a suitability of yellow ligaments for age estimation based on aspartic acid racemization (AAR), which was tested by determination of AAR in total tissue specimens and in purified elastin from yellow ligaments of individuals of known age. AAR was found to increase with age in both sample sets. The purified elastin samples exhibited a much faster kinetics than the total tissue, with ca. 3.7-4.6-fold higher apparent rates. The relationship between AAR and age was much closer in the purified elastin samples ( r=0.96-0.99) and it can therefore be used as a basis for biochemical age estimation. The analysis of total tissue samples cannot be recommended since the AAR values can be strongly influenced even by slight, histologically non-detectable variations in the collagen content. Age estimation based on AAR in purified elastin from yellow ligaments may be a valuable additional tool in the identification of unidentified cadavers, especially in cases where other methods cannot be applied (e.g. no available teeth, body parts).

Accuracy of patient-specific organ dose estimates obtained using an automated image segmentation algorithm.

PubMed

Schmidt, Taly Gilat; Wang, Adam S; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-10-01

The overall goal of this work is to develop a rapid, accurate, and automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using simulations to generate dose maps combined with automated segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. We hypothesized that the autosegmentation algorithm is sufficiently accurate to provide organ dose estimates, since small errors delineating organ boundaries will have minimal effect when computing mean organ dose. A leave-one-out validation study of the automated algorithm was performed with 20 head-neck CT scans expertly segmented into nine regions. Mean organ doses of the automatically and expertly segmented regions were computed from Monte Carlo-generated dose maps and compared. The automated segmentation algorithm estimated the mean organ dose to be within 10% of the expert segmentation for regions other than the spinal canal, with the median error for each organ region below 2%. In the spinal canal region, the median error was [Formula: see text], with a maximum absolute error of 28% for the single-atlas approach and 11% for the multiatlas approach. The results demonstrate that the automated segmentation algorithm can provide accurate organ dose estimates despite some segmentation errors.

Accuracy of patient-specific organ dose estimates obtained using an automated image segmentation algorithm

PubMed Central

Schmidt, Taly Gilat; Wang, Adam S.; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-01-01

Abstract. The overall goal of this work is to develop a rapid, accurate, and automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using simulations to generate dose maps combined with automated segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. We hypothesized that the autosegmentation algorithm is sufficiently accurate to provide organ dose estimates, since small errors delineating organ boundaries will have minimal effect when computing mean organ dose. A leave-one-out validation study of the automated algorithm was performed with 20 head-neck CT scans expertly segmented into nine regions. Mean organ doses of the automatically and expertly segmented regions were computed from Monte Carlo-generated dose maps and compared. The automated segmentation algorithm estimated the mean organ dose to be within 10% of the expert segmentation for regions other than the spinal canal, with the median error for each organ region below 2%. In the spinal canal region, the median error was −7%, with a maximum absolute error of 28% for the single-atlas approach and 11% for the multiatlas approach. The results demonstrate that the automated segmentation algorithm can provide accurate organ dose estimates despite some segmentation errors. PMID:27921070

On the confounds among retest gains and age-cohort differences in the estimation of within-person change in longitudinal studies: a simulation study.

PubMed

Hoffman, Lesa; Hofer, Scott M; Sliwinski, Martin J

2011-12-01

Although longitudinal designs are the only way in which age changes can be directly observed, a recurrent criticism involves to what extent retest effects may downwardly bias estimates of true age-related cognitive change. Considerable attention has been given to the problem of retest effects within mixed effects models that include separate parameters for longitudinal change over time (usually specified as a function of age) and for the impact of retest (specified as a function of number of exposures). Because time (i.e., intervals between assessment) and number of exposures are highly correlated (and are perfectly correlated in equal interval designs) in most longitudinal studies, the separation of effects of within-person change from effects of retest gains is only possible given certain assumptions (e.g., age convergence). To the extent that cross-sectional and longitudinal effects of age differ, obtained estimates of aging and retest may not be informative. The current simulation study investigated the recovery of within-person change (i.e., aging) and retest effects from repeated cognitive testing as a function of number of waves, age range at baseline, and size and direction of age-cohort differences on the intercept and age slope in age-based models of change. Significant bias and Type I error rates in the estimated effects of retest were observed when these convergence assumptions were not met. These simulation results suggest that retest effects may not be distinguishable from effects of aging-related change and age-cohort differences in typical long-term traditional longitudinal designs.

Dental radiographic indicators, a key to age estimation

PubMed Central

Panchbhai, AS

2011-01-01

Objective The present review article is aimed at describing the radiological methods utilized for human age identification. Methods The application and importance of radiological methods in human age assessment was discussed through the literature survey. Results Following a literature search, 46 articles were included in the study and the relevant information is depicted in the article. Dental tissue is often preserved indefinitely after death. Implementation of radiography is based on the assessment of the extent of calcification of teeth and in turn the degree of formation of crown and root structures, along with the sequence and the stages of eruption. Several radiological techniques can be used to assist in both individual and general identification, including determination of gender, ethnic group and age. The radiographic method is a simpler and cheaper method of age identification compared with histological and biochemical methods. Radiographic and tomographic images have become an essential aid for human identification in forensic dentistry, particularly with the refinement of techniques and the incorporation of information technology resources. Conclusion Based on an appropriate knowledge of the available methods, forensic dentists can choose the most appropriate since the validity of age estimation crucially depends on the method used and its proper application. The multifactorial approach will lead to optimum age assessment. The legal requirements also have to be considered. PMID:21493876

A New Approach of Juvenile Age Estimation using Measurements of the Ilium and Multivariate Adaptive Regression Splines (MARS) Models for Better Age Prediction.

PubMed

Corron, Louise; Marchal, François; Condemi, Silvana; Chaumoître, Kathia; Adalian, Pascal

2017-01-01

Juvenile age estimation methods used in forensic anthropology generally lack methodological consistency and/or statistical validity. Considering this, a standard approach using nonparametric Multivariate Adaptive Regression Splines (MARS) models were tested to predict age from iliac biometric variables of male and female juveniles from Marseilles, France, aged 0-12 years. Models using unidimensional (length and width) and bidimensional iliac data (module and surface) were constructed on a training sample of 176 individuals and validated on an independent test sample of 68 individuals. Results show that MARS prediction models using iliac width, module and area give overall better and statistically valid age estimates. These models integrate punctual nonlinearities of the relationship between age and osteometric variables. By constructing valid prediction intervals whose size increases with age, MARS models take into account the normal increase of individual variability. MARS models can qualify as a practical and standardized approach for juvenile age estimation. © 2016 American Academy of Forensic Sciences.

Precision and accuracy of commonly used dental age estimation charts for the New Zealand population.

PubMed

Baylis, Stephanie; Bassed, Richard

2017-08-01

Little research has been undertaken for the New Zealand population in the field of dental age estimation. This research to date indicates there are differences in dental developmental rates between the New Zealand population and other global population groups, and within the New Zealand population itself. Dental age estimation methods range from dental development charts to complex biometric analysis. Dental development charts are not the most accurate method of dental age estimation, but are time saving in their use. They are an excellent screening tool, particularly for post-mortem identification purposes, and for assessing variation from population norms in living individuals. The aim of this study was to test the precision and accuracy of three dental development charts (Schour and Massler, Blenkin and Taylor, and the London Atlas), used to estimate dental age of a sample of New Zealand juveniles between the ages of 5 and 18 years old (n=875). Percentage 'best fit' to correct age category and to expected chart stage were calculated to determine which chart was the most precise for the sample. Chronological ages were compared to estimated dental ages using a two-tailed paired t-test (P<0.05) for each of the three methods. The mean differences between CA and DA were calculated to determine bias and the absolute mean differences were calculated to indicate accuracy. The results of this study show that while accuracy and precision were low for all charts tested against the New Zealand population sample, the Blenkin and Taylor Australian charts performed best overall. Copyright © 2017 Elsevier B.V. All rights reserved.

The French-Canadian data set of Demirjian for dental age estimation: a systematic review and meta-analysis.

PubMed

Jayaraman, Jayakumar; Wong, Hai Ming; King, Nigel M; Roberts, Graham J

2013-07-01

Estimation of age of an individual can be performed by evaluating the pattern of dental development. A dataset for age estimation based on the dental maturity of a French-Canadian population was published over 35 years ago and has become the most widely accepted dataset. The applicability of this dataset has been tested on different population groups. To estimate the observed differences between Chronological age (CA) and Dental age (DA) when the French Canadian dataset was used to estimate the age of different population groups. A systematic search of literature for papers utilizing the French Canadian dataset for age estimation was performed. All language articles from PubMed, Embase and Cochrane databases were electronically searched for terms 'Demirjian' and 'Dental age' published between January 1973 and December 2011. A hand search of articles was also conducted. A total of 274 studies were identified from which 34 studies were included for qualitative analysis and 12 studies were included for quantitative assessment and meta-analysis. When synthesizing the estimation results from different population groups, on average, the Demirjian dataset overestimated the age of females by 0.65 years (-0.10 years to +2.82 years) and males by 0.60 years (-0.23 years to +3.04 years). The French Canadian dataset overestimates the age of the subjects by more than six months and hence this dataset should be used only with considerable caution when estimating age of group of subjects of any global population. Copyright © 2013 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Paleoglaciation of the Tibetan Plateau based on exposure ages and ELA depression estimates

NASA Astrophysics Data System (ADS)

Heyman, Jakob

2014-05-01

The Tibetan Plateau holds a major part of all glaciers outside the polar regions and an ample record of past glaciations. The glacial history of the Tibetan Plateau has attracted significant interest, with a large body of research investigating the extent, timing, and climatic implications of past glaciations. Here I present an extensive compilation of exposure ages and equilibrium line altitude (ELA) depression estimates from glacial deposits across the Tibetan Plateau to address the timing and degree of past glaciations. I compiled Be-10 exposure age data for a total of 1877 samples and recalculated exposure ages using an updated (lower) global Be-10 production rate. All samples were organized in groups of individual glacial deposits where each deposit represents one glacial event enabling evaluation of the exposure age clustering. For each glacial deposit I estimated the ELA depression based on a simple toe to headwall ratio approach using Google Earth. To discriminate good (well-clustered) from poor (scattered) exposure age groups the glacial deposits were divided into three groups based on exposure age clustering. A major part of the glacial deposits have scattered exposure ages affected by prior or incomplete exposure, complicating exposure age interpretations. The well-clustered exposure age groups are primarily from mountain ranges along the margins of the Tibetan Plateau with a main peak in age between 10 and 30 ka, indicating glacial advances during the global last glacial maximum (LGM). A large number of exposure ages older than 30 ka indicates maximum glaciation predating the LGM, but the exposure age scatter generally prohibits accurate definition of the glacial chronology. The ELA depression estimates scatter significantly, but a major part is remarkably low. Average ELA depressions of 333 ± 191 m for the LGM and 494 ± 280 m for the pre-LGM exposure indicate restricted glacier expansion and limited glacial cooling.

What automated age estimation of hand and wrist MRI data tells us about skeletal maturation in male adolescents.

PubMed

Urschler, Martin; Grassegger, Sabine; Štern, Darko

2015-01-01

Age estimation of individuals is important in human biology and has various medical and forensic applications. Recent interest in MR-based methods aims to investigate alternatives for established methods involving ionising radiation. Automatic, software-based methods additionally promise improved estimation objectivity. To investigate how informative automatically selected image features are regarding their ability to discriminate age, by exploring a recently proposed software-based age estimation method for MR images of the left hand and wrist. One hundred and two MR datasets of left hand images are used to evaluate age estimation performance, consisting of bone and epiphyseal gap volume localisation, computation of one age regression model per bone mapping image features to age and fusion of individual bone age predictions to a final age estimate. Quantitative results of the software-based method show an age estimation performance with a mean absolute difference of 0.85 years (SD = 0.58 years) to chronological age, as determined by a cross-validation experiment. Qualitatively, it is demonstrated how feature selection works and which image features of skeletal maturation are automatically chosen to model the non-linear regression function. Feasibility of automatic age estimation based on MRI data is shown and selected image features are found to be informative for describing anatomical changes during physical maturation in male adolescents.

Comparative precision of age estimates from two southern reservoir populations of paddlefish [Polyodon spathula (Walbaum, 1792)

USGS Publications Warehouse

Long, James M.; Nealis, Ashley

2017-01-01

The aim of the study was to determine whether location and sex affected the age precision estimates between two southern, reservoir populations of paddlefish [Polyodon spathula (Walbaum, 1792)]. From 589 paddlefish collected in Grand Lake and Keystone Lake, Oklahoma in 2011, ages from dentaries were estimated using three independent readers and precision was compared with coefficient of variation between locations and sexes. Ages were more precisely estimated from Grand Lake and from females.

Age estimation based on pulp chamber volume of first molars from cone-beam computed tomography images.

PubMed

Ge, Zhi-pu; Ma, Ruo-han; Li, Gang; Zhang, Ji-zong; Ma, Xu-chen

2015-08-01

To establish a method that can be used for human age estimation on the basis of pulp chamber volume of first molars and to identify whether the method is good enough for age estimation in real human cases. CBCT images of 373 maxillary first molars and 372 mandibular first molars were collected to establish the mathematical model from 190 female and 213 male patients whose age between 12 and 69 years old. The inclusion criteria of the first molars were: no caries, no excessive tooth wear, no dental restorations, no artifacts due to metal restorative materials present in adjacent teeth, and no pulpal calcification. All the CBCT images were acquired with a CBCT unit NewTom VG (Quantitative Radiology, Verona, Italy) and reconstructed with a voxel-size of 0.15mm. The images were subsequently exported as DICOM data sets and imported into an open source 3D image semi-automatic segmenting and voxel-counting software ITK-SNAP 2.4 for the calculation of pulp chamber volumes. A logarithmic regression analysis was conducted with age as dependent variable and pulp chamber volume as independent variables to establish a mathematical model for the human age estimation. To identify the precision and accuracy of the model for human age estimation, another 104 maxillary first molars and 103 mandibular first molars from 55 female and 57 male patients whose age between 12 and 67 years old were collected, too. Mean absolute error and root mean square error between the actual age and estimated age were used to determine the precision and accuracy of the mathematical model. The study was approved by the Institutional Review Board of Peking University School and Hospital of Stomatology. A mathematical model was suggested for: AGE=117.691-26.442×ln (pulp chamber volume). The regression was statistically significant (p=0.000<0.01). The coefficient of determination (R(2)) was 0.564. There is a mean absolute error of 8.122 and root mean square error of 5.603 between the actual age and

Estimation of age in the living: in matters civil and criminal.

PubMed

Aggrawal, Anil

2009-05-11

Estimation of age is one of the main tasks of a forensic practitioner, especially in third world countries, where many births take place in rural settings without the benefit of the expert supervision of a trained obstetrician. Such births are poorly recorded or more often not recorded at all in terms of exact dates. In many other cases, records are fraudulently falsified for some gain, e.g. to get government jobs or pensions. Developed countries, where ordinarily the birth records are meticulously maintained, are not immune to this problem either. Estimation of the age of living individuals may be needed here for refugees or other persons who arrive without acceptable identification papers. A wide variety of methods are used by the forensic clinician to assess the age of the individual in such cases. This paper discusses and evaluates the most common methods used in India, although the methods can be effectively utilized by medico-legal professionals anywhere in the world.

Performance of Willem's dental age estimation method in children: A systematic review and meta-analysis.

PubMed

Mohd Yusof, Mohd Yusmiaidil Putera; Wan Mokhtar, Ilham; Rajasekharan, Sivaprakash; Overholser, Rosanna; Martens, Luc

2017-11-01

Through numerous validation and method comparison studies on different populations, the Willems method exhibited a superior accuracy. This article aims to systematically examine how accurate the application of Willems dental age method on children of different age groups and its performance based on various populations and regions. A strategic literature search of PubMed, MEDLINE, Web of Science, EMBASE and hand searching were used to identify the studies published up to September 2014 that estimated the dental age using the Willems method (modified Demirjian), with a populations, intervention, comparisons and outcomes (PICO) search strategy using MeSH keywords, focusing on the question: How much Willems method deviates from the chronological age in estimating age in children? Standardized mean differences were calculated for difference of dental age to chronological age by using random effects model. Subgroup analyses were performed to evaluate potential heterogeneity. Of 116 titles retrieved based on the standardized search strategy, only 19 articles fulfilled the inclusion criteria for quantitative analysis. The pooled estimates were separately kept as underestimation (n=7) and overestimation (n=12) of chronological age groups for both genders according to primary studies. On absolute values, females (underestimated by 0.13; 95% CI: 0.09-0.18 and overestimated by 0.27; 95% CI: 0.17-0.36) exhibited better accuracy than males (underestimated by 0.28; 95% CI: 0.14-0.42 and overestimated by 0.33; 95% CI: 0.22-0.44). For comparison purposes, the overall pooled estimate overestimated the age by 0.10 (95% CI: -0.06 to 0.26) and 0.09 (95% CI: -0.09 to 0.19) for males and females, respectively. There was no significant difference between the young and older child in subgroup analysis using omnibus test. The mean age between different regions exhibited no statistically significant. The use of Willems method is appropriate to estimate age in children considering its

Dental age estimation from the developmental stage of the third molars in western Chinese population.

PubMed

Li, Guo; Ren, Jiayin; Zhao, Shuping; Liu, Yuanyuan; Li, Na; Wu, Wanhong; Yuan, Shanshan; Wang, Hu

2012-06-10

The purpose of this study is to provide reference data about estimating dental age from third molars of the western Chinese population for comparing with other populations and being applied to the age estimation of western Chinese juveniles and adolescents. A total of 2078 digital panoramic radiographs of 989 male and 1089 female Chinese subjects aged between 5 and 23 years were examined. The mineralization status of the third molars was assessed using the formation stages described by Demirjian et al. with two modifications. The results showed that the development of third molars in the western Chinese population was likely to begin at age 5 in both males and females. The third molars 28 and 48 showed significantly higher frequency in females than in males. The third molars 18 in the stage 1, 38 in the stages 1, A and G, and 48 in the stage H showed significantly older average age in females than in males. The Demirjian's stages C and D could be used as a reference stage to determine dichotomously whether a western Chinese is more likely to be under or above age 14 or 16, respectively. This study provided reference data for the age estimation of western Chinese juveniles and adolescents by the mineralization stages of the third molar. Apart from forensic age determination in living subjects, the presented reference data can also be used for age estimations of unidentified corpses and skeletons. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

An evaluation of agreement between pectoral spines and otoliths for estimating ages of catfishes

USGS Publications Warehouse

Olive, J.A.; Schramm, Harold; Gerard, Patrick D.; Irwin, E.

2011-01-01

Otoliths have been shown to provide more accurate ages than pectoral spine sections for several catfish populations; but sampling otoliths requires euthanizing the specimen, whereas spines can be sampled non-lethally. To evaluate whether, and under what conditions, spines provide the same or similar age estimates as otoliths, we examined data sets of individual fish aged from pectoral spines and otoliths for six blue catfish Ictalurus furcatus populations (n=420), 14 channel catfish Ictalurus punctatus populations (n=997), and 10 flathead catfish Pylodictus olivaris populations (n=947) from lotic and lentic waters throughout the central and eastern U.S. Logistic regression determined that agreement between ages estimated from otoliths and spines was consistently related to age, but inconsistently related to growth rate. When modeled at mean growth rate, we found at least 80% probability of no difference in spine- and otolith-assigned ages up to ages 4 and 5 for blue and channel catfish, respectively. For flathead catfish, an 80% probability of agreement between spine- and otolith-assigned ages did not occur at any age due to high incidence of differences in assigned ages even for age-1 fish. Logistic regression models predicted at least 80% probability that spine and otolith ages differed by ≤1 year up to ages 13, 16, and 9 for blue, channel, and flathead catfish, respectively. Age-bias assessment found mean spine-assigned age differed by less than 1 year from otolith-assigned age up to ages 19, 9, and 17 for blue catfish, channel catfish, and flathead catfish, respectively. These results can be used to help guide decisions about which structure is most appropriate for estimating catfish ages for particular populations and management objectives.

Assessment of the dorsal fin spine for chimaeroid (Holocephali: Chimaeriformes) age estimation.

PubMed

Barnett, L A K; Ebert, D A; Cailliet, G M

2009-10-01

Previous attempts to age chimaeroids have not rigorously tested assumptions of dorsal fin spine growth dynamics. Here, novel imaging and data-analysis techniques revealed that the dorsal fin spine of the spotted ratfish Hydrolagus colliei is an unreliable structure for age estimation. Variation among individuals in the relationship between spine width and distance from the spine tip indicated that the technique of transverse sectioning may impart imprecision and bias to age estimates. The number of growth-band pairs observed by light microscopy in the inner dentine layer was not a good predictor of body size. Mineral density gradients, indicative of growth zones, were absent in the dorsal fin spine of H. colliei, decreasing the likelihood that the bands observed by light microscopy represent a record of growth with consistent periodicity. These results indicate that the hypothesis of aseasonal growth remains plausible and it should not be assumed that chimaeroid age is quantifiable by standard techniques.

Precise attitude rate estimation using star images obtained by mission telescope for satellite missions

NASA Astrophysics Data System (ADS)

Inamori, Takaya; Hosonuma, Takayuki; Ikari, Satoshi; Saisutjarit, Phongsatorn; Sako, Nobutada; Nakasuka, Shinichi

2015-02-01

Recently, small satellites have been employed in various satellite missions such as astronomical observation and remote sensing. During these missions, the attitudes of small satellites should be stabilized to a higher accuracy to obtain accurate science data and images. To achieve precise attitude stabilization, these small satellites should estimate their attitude rate under the strict constraints of mass, space, and cost. This research presents a new method for small satellites to precisely estimate angular rate using star blurred images by employing a mission telescope to achieve precise attitude stabilization. In this method, the angular velocity is estimated by assessing the quality of a star image, based on how blurred it appears to be. Because the proposed method utilizes existing mission devices, a satellite does not require additional precise rate sensors, which makes it easier to achieve precise stabilization given the strict constraints possessed by small satellites. The research studied the relationship between estimation accuracy and parameters used to achieve an attitude rate estimation, which has a precision greater than 1 × 10-6 rad/s. The method can be applied to all attitude sensors, which use optics systems such as sun sensors and star trackers (STTs). Finally, the method is applied to the nano astrometry satellite Nano-JASMINE, and we investigate the problems that are expected to arise with real small satellites by performing numerical simulations.

A Novel Method for Age Estimation in Solar-Type Stars Through GALEX FUV Magnitudes

NASA Astrophysics Data System (ADS)

Ho, Kelly; Subramonian, Arjun; Smith, Graeme; Shouru Shieh

2018-01-01

Utilizing an inverse association known to exist between Galaxy Evolution Explorer (GALEX) far ultraviolet (FUV) magnitudes and the chromospheric activity of F, G, and K dwarfs, we explored a method of age estimation in solar-type stars through GALEX FUV magnitudes. Sample solar-type star data were collected from refereed publications and filtered by B-V and absolute visual magnitude to ensure similarities in temperature and luminosity to the Sun. We determined FUV-B and calculated a residual index Q for all the stars, using the temperature-induced upper bound on FUV-B as the fiducial. Plotting current age estimates for the stars against Q, we discovered a strong and significant association between the variables. By applying a log-linear transformation to the data to produce a strong correlation between Q and loge Age, we confirmed the association between Q and age to be exponential. Thus, least-squares regression was used to generate an exponential model relating Q to age in solar-type stars, which can be used by astronomers. The Q-method of stellar age estimation is simple and more efficient than existing spectroscopic methods and has applications to galactic archaeology and stellar chemical composition analysis.

Effect of windowing on lithosphere elastic thickness estimates obtained via the coherence method: Results from northern South America

NASA Astrophysics Data System (ADS)

Ojeda, GermáN. Y.; Whitman, Dean

2002-11-01

The effective elastic thickness (Te) of the lithosphere is a parameter that describes the flexural strength of a plate. A method routinely used to quantify this parameter is to calculate the coherence between the two-dimensional gravity and topography spectra. Prior to spectra calculation, data grids must be "windowed" in order to avoid edge effects. We investigated the sensitivity of Te estimates obtained via the coherence method to mirroring, Hanning and multitaper windowing techniques on synthetic data as well as on data from northern South America. These analyses suggest that the choice of windowing technique plays an important role in Te estimates and may result in discrepancies of several kilometers depending on the selected windowing method. Te results from mirrored grids tend to be greater than those from Hanning smoothed or multitapered grids. Results obtained from mirrored grids are likely to be over-estimates. This effect may be due to artificial long wavelengths introduced into the data at the time of mirroring. Coherence estimates obtained from three subareas in northern South America indicate that the average effective elastic thickness is in the range of 29-30 km, according to Hanning and multitaper windowed data. Lateral variations across the study area could not be unequivocally determined from this study. We suggest that the resolution of the coherence method does not permit evaluation of small (i.e., ˜5 km), local Te variations. However, the efficiency and robustness of the coherence method in rendering continent-scale estimates of elastic thickness has been confirmed.

Age- and gender-specific estimates of cumulative CT dose over 5 years using real radiation dose tracking data in children.

PubMed

Lee, Eunsol; Goo, Hyun Woo; Lee, Jae-Yeong

2015-08-01

It is necessary to develop a mechanism to estimate and analyze cumulative radiation risks from multiple CT exams in various clinical scenarios in children. To identify major contributors to high cumulative CT dose estimates using actual dose-length product values collected for 5 years in children. Between August 2006 and July 2011 we reviewed 26,937 CT exams in 13,803 children. Among them, we included 931 children (median age 3.5 years, age range 0 days-15 years; M:F = 533:398) who had 5,339 CT exams. Each child underwent at least three CT scans and had accessible radiation dose reports. Dose-length product values were automatically extracted from DICOM files and we used recently updated conversion factors for age, gender, anatomical region and tube voltage to estimate CT radiation dose. We tracked the calculated CT dose estimates to obtain a 5-year cumulative value for each child. The study population was divided into three groups according to the cumulative CT dose estimates: high, ≥30 mSv; moderate, 10-30 mSv; and low, <10 mSv. We reviewed clinical data and CT protocols to identify major contributors to high and moderate cumulative CT dose estimates. Median cumulative CT dose estimate was 5.4 mSv (range 0.5-71.1 mSv), and median number of CT scans was 4 (range 3-36). High cumulative CT dose estimates were most common in children with malignant tumors (57.9%, 11/19). High frequency of CT scans was attributed to high cumulative CT dose estimates in children with ventriculoperitoneal shunt (35 in 1 child) and malignant tumors (range 18-49). Moreover, high-dose CT protocols, such as multiphase abdomen CT (median 4.7 mSv) contributed to high cumulative CT dose estimates even in children with a low number of CT scans. Disease group, number of CT scans, and high-dose CT protocols are major contributors to higher cumulative CT dose estimates in children.

Estimating the Spatial Distribution of Groundwater Age Using Synoptic Surveys of Environmental Tracers in Streams

NASA Astrophysics Data System (ADS)

Gardner, W. P.

2017-12-01

A model which simulates tracer concentration in surface water as a function the age distribution of groundwater discharge is used to characterize groundwater flow systems at a variety of spatial scales. We develop the theory behind the model and demonstrate its application in several groundwater systems of local to regional scale. A 1-D stream transport model, which includes: advection, dispersion, gas exchange, first-order decay and groundwater inflow is coupled a lumped parameter model that calculates the concentration of environmental tracers in discharging groundwater as a function of the groundwater residence time distribution. The lumped parameters, which describe the residence time distribution, are allowed to vary spatially, and multiple environmental tracers can be simulated. This model allows us to calculate the longitudinal profile of tracer concentration in streams as a function of the spatially variable groundwater age distribution. By fitting model results to observations of stream chemistry and discharge, we can then estimate the spatial distribution of groundwater age. The volume of groundwater discharge to streams can be estimated using a subset of environmental tracers, applied tracers, synoptic stream gauging or other methods, and the age of groundwater then estimated using the previously calculated groundwater discharge and observed environmental tracer concentrations. Synoptic surveys of SF6, CFC's, 3H and 222Rn, along with measured stream discharge are used to estimate the groundwater inflow distribution and mean age for regional scale surveys of the Berland River in west-central Alberta. We find that groundwater entering the Berland has observable age, and that the age estimated using our stream survey is of similar order to limited samples from groundwater wells in the region. Our results show that the stream can be used as an easily accessible location to constrain the regional scale spatial distribution of groundwater age.

Determinants and consequences of discrepancies in menstrual and ultrasonographic gestational age estimates.

PubMed

Morin, Isabelle; Morin, Lucie; Zhang, Xun; Platt, Robert W; Blondel, Béatrice; Bréart, Gérard; Usher, Robert; Kramer, Michael S

2005-02-01

To assess the association between maternal and fetal characteristics and discrepancy between last normal menstrual period and early (<20 weeks) ultrasound-based gestational age and the association between discrepancies and pregnancy outcomes. Hospital-based cohort study. Montreal, Canada. A total of 46,514 women with both menstrual- and early ultrasound-based gestational age estimates. Positive (last normal menstrual period > early ultrasound, i.e. menstrual-based gestational age is higher than early ultrasound-based gestational age, so that the expected date of delivery is earlier with the menstrual-based gestational age) discrepancies > or =+7 days, mean birthweight, low birthweight, stillbirth and in-hospital neonatal death. Multiparous mothers and those with diabetes, small stature or high pre-pregnancy body mass index were more likely to have positive discrepancies. The proportion of women with discrepancies > or =+7 days was significantly higher among chromosomally malformed and female fetuses. The mean birthweight declined with increasingly positive differences. The risk of low birthweight was significantly higher for positive differences. Associations with fetal growth measures were more plausible with early ultrasound estimates. Although most discrepancies between last normal menstrual period- and early ultrasound-based gestational age are attributable to errors in menstrual dating, our results suggest that some positive differences reflect early growth restriction.

How and Where Young Adults Obtain Marijuana. The NSDUH Report. Issue 20

ERIC Educational Resources Information Center

Substance Abuse and Mental Health Services Administration, 2006

2006-01-01

The National Survey on Drug Use and Health (NSDUH) asks persons aged 12 or older about their use of marijuana or hashish in the past year, including their frequency of use. This report focuses on how and where past year marijuana users aged 18 to 25 obtained their most recently used marijuana. Findings include estimates from the combined 2002,…

Accuracy of patient specific organ-dose estimates obtained using an automated image segmentation algorithm

NASA Astrophysics Data System (ADS)

Gilat-Schmidt, Taly; Wang, Adam; Coradi, Thomas; Haas, Benjamin; Star-Lack, Josh

2016-03-01

The overall goal of this work is to develop a rapid, accurate and fully automated software tool to estimate patient-specific organ doses from computed tomography (CT) scans using a deterministic Boltzmann Transport Equation solver and automated CT segmentation algorithms. This work quantified the accuracy of organ dose estimates obtained by an automated segmentation algorithm. The investigated algorithm uses a combination of feature-based and atlas-based methods. A multiatlas approach was also investigated. We hypothesize that the auto-segmentation algorithm is sufficiently accurate to provide organ dose estimates since random errors at the organ boundaries will average out when computing the total organ dose. To test this hypothesis, twenty head-neck CT scans were expertly segmented into nine regions. A leave-one-out validation study was performed, where every case was automatically segmented with each of the remaining cases used as the expert atlas, resulting in nineteen automated segmentations for each of the twenty datasets. The segmented regions were applied to gold-standard Monte Carlo dose maps to estimate mean and peak organ doses. The results demonstrated that the fully automated segmentation algorithm estimated the mean organ dose to within 10% of the expert segmentation for regions other than the spinal canal, with median error for each organ region below 2%. In the spinal canal region, the median error was 7% across all data sets and atlases, with a maximum error of 20%. The error in peak organ dose was below 10% for all regions, with a median error below 4% for all organ regions. The multiple-case atlas reduced the variation in the dose estimates and additional improvements may be possible with more robust multi-atlas approaches. Overall, the results support potential feasibility of an automated segmentation algorithm to provide accurate organ dose estimates.

Forensic individual age estimation with DNA: From initial approaches to methylation tests.

PubMed

Freire-Aradas, A; Phillips, C; Lareu, M V

2017-07-01

Individual age estimation is a key factor in forensic science analysis that can provide very useful information applicable to criminal, legal, and anthropological investigations. Forensic age inference was initially based on morphological inspection or radiography and only later began to adopt molecular approaches. However, a lack of accuracy or technical problems hampered the introduction of these DNA-based methodologies in casework analysis. A turning point occurred when the epigenetic signature of DNA methylation was observed to gradually change during an individual´s lifespan. In the last four years, the number of publications reporting DNA methylation age-correlated changes has gradually risen and the forensic community now has a range of age methylation tests applicable to forensic casework. Most forensic age predictor models have been developed based on blood DNA samples, but additional tissues are now also being explored. This review assesses the most widely adopted genes harboring methylation sites, detection technologies, statistical age-predictive analyses, and potential causes of variation in age estimates. Despite the need for further work to improve predictive accuracy and establishing a broader range of tissues for which tests can analyze the most appropriate methylation sites, several forensic age predictors have now been reported that provide consistency in their prediction accuracies (predictive error of ±4 years); this makes them compelling tools with the potential to contribute key information to help guide criminal investigations. Copyright © 2017 Central Police University.

Comparison of two viewing methods for estimating largemouth bass and walleye ages from sectioned otoliths and dorsal spines

USGS Publications Warehouse

Wegleitner, Eric J.; Isermann, Daniel A.

2017-01-01

Many biologists use digital images for estimating ages of fish, but the use of images could lead to differences in age estimates and precision because image capture can produce changes in light and clarity compared to directly viewing structures through a microscope. We used sectioned sagittal otoliths from 132 Largemouth Bass Micropterus salmoides and sectioned dorsal spines and otoliths from 157 Walleyes Sander vitreus to determine whether age estimates and among‐reader precision were similar when annuli were enumerated directly through a microscope or from digital images. Agreement of ages between viewing methods for three readers were highest for Largemouth Bass otoliths (75–89% among readers), followed by Walleye otoliths (63–70%) and Walleye dorsal spines (47–64%). Most discrepancies (72–96%) were ±1 year, and differences were more prevalent for age‐5 and older fish. With few exceptions, mean ages estimated from digital images were similar to ages estimated via directly viewing the structures through the microscope, and among‐reader precision did not vary between viewing methods for each structure. However, the number of disagreements we observed suggests that biologists should assess potential differences in age structure that could arise if images of calcified structures are used in the age estimation process.

Accuracy and sampling error of two age estimation techniques using rib histomorphometry on a modern sample.

PubMed

García-Donas, Julieta G; Dyke, Jeffrey; Paine, Robert R; Nathena, Despoina; Kranioti, Elena F

2016-02-01

Most age estimation methods are proven problematic when applied in highly fragmented skeletal remains. Rib histomorphometry is advantageous in such cases; yet it is vital to test and revise existing techniques particularly when used in legal settings (Crowder and Rosella, 2007). This study tested Stout & Paine (1992) and Stout et al. (1994) histological age estimation methods on a Modern Greek sample using different sampling sites. Six left 4th ribs of known age and sex were selected from a modern skeletal collection. Each rib was cut into three equal segments. Two thin sections were acquired from each segment. A total of 36 thin sections were prepared and analysed. Four variables (cortical area, intact and fragmented osteon density and osteon population density) were calculated for each section and age was estimated according to Stout & Paine (1992) and Stout et al. (1994). The results showed that both methods produced a systemic underestimation of the individuals (to a maximum of 43 years) although a general improvement in accuracy levels was observed when applying the Stout et al. (1994) formula. There is an increase of error rates with increasing age with the oldest individual showing extreme differences between real age and estimated age. Comparison of the different sampling sites showed small differences between the estimated ages suggesting that any fragment of the rib could be used without introducing significant error. Yet, a larger sample should be used to confirm these results. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Age-specific survival estimates of King Eiders derived from satellite telemetry

USGS Publications Warehouse

Oppel, Steffen; Powell, Abby N.

2010-01-01

Age- and sex-specific survival and dispersal are important components in the dynamics and genetic structure of bird populations. For many avian taxa survival rates at the adult and juvenile life stages differ, but in long-lived species juveniles' survival is logistically challenging to study. We present the first estimates of hatch-year annual survival rates for a sea duck, the King Eider (Somateria spectabilis), estimated from satellite telemetry. From 2006 to 2008 we equipped pre-fiedging King Eiders with satellite transmitters on breeding grounds in Alaska and estimated annual survival rates during their first 2 years of life with known-fate models. We compared those estimates to survival rates of adults marked in the same area from 2002 to 2008. Hatch-year survival varied by season during the first year of life, and model-averaged annual survival rate was 0.67 (95% CI: 0.48–0.80). We did not record any mortality during the second year and were therefore unable to estimate second-year survival rate. Adults' survival rate was constant through the year (0.94, 95% CI: 0.86–0.97). No birds appeared to breed during their second summer. While 88% of females with an active transmitter (n = 9) returned to their natal area at the age of 2 years, none of the 2-year old males (n = 3) did. This pattern indicates that females' natal philopatry is high and suggests that males' higher rates of dispersal may account for sex-specific differences in apparent survival rates of juvenile sea ducks when estimated with mark—recapture methods.

An iterative procedure for obtaining maximum-likelihood estimates of the parameters for a mixture of normal distributions, Addendum

NASA Technical Reports Server (NTRS)

Peters, B. C., Jr.; Walker, H. F.

1975-01-01

New results and insights concerning a previously published iterative procedure for obtaining maximum-likelihood estimates of the parameters for a mixture of normal distributions were discussed. It was shown that the procedure converges locally to the consistent maximum likelihood estimate as long as a specified parameter is bounded between two limits. Bound values were given to yield optimal local convergence.

Threshold groundwater ages and young water fractions estimated from 3H, 3He, and 14C

NASA Astrophysics Data System (ADS)

Kirchner, James; Jasechko, Scott

2016-04-01

It is widely recognized that a water sample taken from a running stream is not described by a single age, but rather by a distribution of ages. It is less widely recognized that the same principle holds true for groundwaters, as indicated by the commonly observed discordances between model ages obtained from different tracers (e.g., 3H vs 14C) in the same sample. Water age distributions are often characterized by their mean residence times (MRT's). However, MRT estimates are highly uncertain because they depend on the shape of the assumed residence time distribution (in particular on the thickness of the long-time tail), which is difficult or impossible to constrain with data. Furthermore, because MRT's are typically nonlinear functions of age tracer concentrations, they are subject to aggregation bias. That is, MRT estimates derived from a mixture of waters with different ages (and thus different tracer concentrations) will systematically underestimate the mixture's true mean age. Here, building on recent work with stable isotope tracers in surface waters [1-3], we present a new framework for using 3H, 3He and 14C to characterize groundwater age distributions. Rather than describing groundwater age distributions by their MRT, we characterize them by the fraction of the distribution that is younger or older than a threshold age. The threshold age that separates "young" from "old" water depends on the characteristics of the specific tracer, including its history of atmospheric inputs. Our approach depends only on whether a given slice of the age distribution is younger or older than the threshold age, but not on how much younger or older it is. Thus our approach is insensitive to the tails of the age distribution, and is therefore relatively unaffected by uncertainty in the distribution's shape. Here we show that concentrations of 3H, 3He, and 14C are almost linearly related to the fractions of water that are younger or older than specified threshold ages. These

The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group

NASA Astrophysics Data System (ADS)

Jones, Jeremy; White, R. J.; Boyajian, T.; Schaefer, G.; Baines, E.; Ireland, M.; Patience, J.; ten Brummelaar, T.; McAlister, H.; Ridgway, S. T.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

2015-11-01

We have observed and spatially resolved a set of seven A-type stars in the nearby Ursa Major moving group with the Classic, CLIMB, and PAVO beam combiners on the Center for High Angular Resolution Astronomy Array. At least four of these stars have large rotational velocities (v{sin}i ≳ 170 {km} {{{s}}}-1) and are expected to be oblate. These interferometric measurements, the stars’ observed photometric energy distributions, and v{sin}i values are used to computationally construct model oblate stars from which stellar properties (inclination, rotational velocity, and the radius and effective temperature as a function of latitude, etc.) are determined. The results are compared with MESA stellar evolution models to determine masses and ages. The value of this new technique is that it enables the estimation of the fundamental properties of rapidly rotating stars without the need to fully image the star. It can thus be applied to stars with sizes comparable to the interferometric resolution limit as opposed to those that are several times larger than the limit. Under the assumption of coevality, the spread in ages can be used as a test of both the prescription presented here and the MESA evolutionary code for rapidly rotating stars. With our validated technique, we combine these age estimates and determine the age of the moving group to be 414 ± 23 Myr, which is consistent with, but much more precise than previous estimates.

Validity and reliability of dental age estimation of teeth root translucency based on digital luminance determination.

PubMed

Ramsthaler, Frank; Kettner, Mattias; Verhoff, Marcel A

2014-01-01

In forensic anthropological casework, estimating age-at-death is key to profiling unknown skeletal remains. The aim of this study was to examine the reliability of a new, simple, fast, and inexpensive digital odontological method for age-at-death estimation. The method is based on the original Lamendin method, which is a widely used technique in the repertoire of odontological aging methods in forensic anthropology. We examined 129 single root teeth employing a digital camera and imaging software for the measurement of the luminance of the teeth's translucent root zone. Variability in luminance detection was evaluated using statistical technical error of measurement analysis. The method revealed stable values largely unrelated to observer experience, whereas requisite formulas proved to be camera-specific and should therefore be generated for an individual recording setting based on samples of known chronological age. Multiple regression analysis showed a highly significant influence of the coefficients of the variables "arithmetic mean" and "standard deviation" of luminance for the regression formula. For the use of this primer multivariate equation for age-at-death estimation in casework, a standard error of the estimate of 6.51 years was calculated. Step-by-step reduction of the number of embedded variables to linear regression analysis employing the best contributor "arithmetic mean" of luminance yielded a regression equation with a standard error of 6.72 years (p < 0.001). The results of this study not only support the premise of root translucency as an age-related phenomenon, but also demonstrate that translucency reflects a number of other influencing factors in addition to age. This new digital measuring technique of the zone of dental root luminance can broaden the array of methods available for estimating chronological age, and furthermore facilitate measurement and age classification due to its low dependence on observer experience.

Challenges in Obtaining Estimates of the Risk of Tuberculosis Infection During Overseas Deployment.

PubMed

Mancuso, James D; Geurts, Mia

2015-12-01

Estimates of the risk of tuberculosis (TB) infection resulting from overseas deployment among U.S. military service members have varied widely, and have been plagued by methodological problems. The purpose of this study was to estimate the incidence of TB infection in the U.S. military resulting from deployment. Three populations were examined: 1) a unit of 2,228 soldiers redeploying from Iraq in 2008, 2) a cohort of 1,978 soldiers followed up over 5 years after basic training at Fort Jackson in 2009, and 3) 6,062 participants in the 2011-2012 National Health and Nutrition Examination Survey (NHANES). The risk of TB infection in the deployed population was low-0.6% (95% confidence interval [CI]: 0.1-2.3%)-and was similar to the non-deployed population. The prevalence of latent TB infection (LTBI) in the U.S. population was not significantly different among deployed and non-deployed veterans and those with no military service. The limitations of these retrospective studies highlight the challenge in obtaining valid estimates of risk using retrospective data and the need for a more definitive study. Similar to civilian long-term travelers, risks for TB infection during deployment are focal in nature, and testing should be targeted to only those at increased risk. © The American Society of Tropical Medicine and Hygiene.

A review on lithium-ion battery ageing mechanisms and estimations for automotive applications

NASA Astrophysics Data System (ADS)

Barré, Anthony; Deguilhem, Benjamin; Grolleau, Sébastien; Gérard, Mathias; Suard, Frédéric; Riu, Delphine

2013-11-01

Lithium-ion batteries have become the focus of research interest, thanks to their numerous benefits for vehicle applications. One main limitation of these technologies resides in the battery ageing. The effects of battery ageing limit its performance and occur throughout their whole life, whether the battery is used or not, which is a major drawback on real usage. Furthermore, degradations take place in every condition, but in different proportions as usage and external conditions interact to provoke degradations. The ageing phenomena are highly complicated to characterize due to the factors cross-dependence. This paper reviews various aspects of recent research and developments, from different fields, on lithium-ion battery ageing mechanisms and estimations. In this paper is presented a summary of techniques, models and algorithms used for battery ageing estimation (SOH, RUL), going from a detailed electrochemical approach to statistical methods based on data. In order to present the accuracy of currently used methods, their respective characteristics are discussed. Remaining challenges are deeply detailed, along with a discussion about the ideal method resulting from existing methods.

Digital radiographic evaluation of mandibular third molar for age estimation in young adults and adolescents of South Indian population using modified Demirjian's method.

PubMed

Mohammed, Rezwana Begum; Koganti, Ravichandra; Kalyan, Siva V; Tircouveluri, Saritha; Singh, Johar Rajvinder; Srinivasulu, Enganti

2014-09-01

In recent years, it has become increasingly important to determine the age of living people for a variety of reasons, including identifying criminal and legal responsibility and for many other social events such as birth certificate, marriage, beginning a job, joining the army and retirement. The aim of this study was to assess the developmental stages of mandibular third molar for estimation of dental age (DA) in different age groups and to evaluate the possible correlation between DA and chronological age (CA) in South Indian population. Digital orthopantomography of 330 subjects (165 males, 165 females) who fit the study and the criteria were obtained. Assessment of mandibular third molar development was performed using Demirjian et al., modified method and DA was assessed using tooth specific stages. The present study showed a significant correlation between DA and CA in both males and females. Third molar development commenced around 9 years and root completion takes place around 18.9 years in males and in females 9 years and 18.6 years respectively. Demirjian modified method underestimated the mean age of males by 0.8 years and females by 0.5 years and also showed that females mature earlier than males in selected population. Digital radiographic assessment of mandibular third molar development can be used to generate mean DA using Demirjian modified method and also the estimated age range for an individual of unknown CA. Since the Demirjian method is based on French-Canadian population, to enhance the accuracy of forensic age estimates based on third molar development, the use of population-specific standards is recommended.

Age ratios as estimators of productivity: testing assumptions on a threatened seabird, the marbled murrelet (Brachyramphus marmoratus)

Treesearch

M. Zachariah Peery; Benjamin H. Becker; Steven R. Beissinger

2007-01-01

The ratio of hatch-year (HY) to after-hatch-year (AHY) individuals (HY:AHY ratio) can be a valuable metric for estimating avian productivity because it does not require monitoring individual breeding sites and can often be estimated across large geographic and temporal scales. However, rigorous estimation of age ratios requires that both young and adult age classes are...

Mineralization of mandibular third molars can estimate chronological age--Brazilian indices.

PubMed

de Oliveira, Fernando Toledo; Capelozza, Ana Lúcia Álvares; Lauris, José Roberto Pereira; de Bullen, Izabel Regina Fischer Rubira

2012-06-10

Forensic age estimation is an important element of anthropological research, as it produces one of the primary sources of data that researchers use to establish the identity of a person living or the identity of unknown bodily remains. The aim of this study was to determine if the chronology of third molar mineralization could be an accurate indicator of estimated age in a sample Brazilian population. If so, mineralization could determine the probability of an individual being 18 years or older. The study evaluated 407 panoramic radiographs of males and females from the past 5 years in order to assess the mineralization status of the mandibular third molars. The evaluation was carried out using an adaptation of Demirjian's system. The results indicated a strong correlation between chronological age and the mineralization of the mandibular third molars. The results indicated that modern Brazilian generation tends to demonstrate an earlier mandibular third molar mineralization than older Brazilian generation and people of other nationalities. Males reached developmental stages slightly earlier than females, but statistically significant differences between the sex were not found. The probability that an individual with third molar mineralization stage H had reached an age of 18 years or older was 96.8-98.6% for males and females, respectively. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Digitized morphometric analysis of dental pulp of permanent mandibular second molar for age estimation of Davangere population.

PubMed

Kumar, Nerella Narendra; Panchaksharappa, Mamatha Gowda; Annigeri, Rajeshwari G

2016-04-01

The aim of the present study is to estimate the age of Davangere population by evaluating the pulp to tooth area ratio (PTR) by using digitized intraoral periapical radiographs of permanent mandibular second molar. 400 intraoral periapical radiograph (IOPA) of permanent mandibular 2nd molar of both the sexes aged 14-60 years were used. Digital camera was used to image the radiographs. Images were computed and PTR was calculated by AUTOCAD software. Intra and Inter observer variability was also assessed. Regression analysis was used to estimate the age of an individual by taking PTR as dependent variable. The mean PTR of males and females was 0.10 ± 0.02 and 0.09 ± 0.02 respectively. Negative correlation was observed, when age was compared with PTR {r = -0.441, -0.406 & -0.419 among males, females and total subjects (p < 0.001)}. Regression analysis showed a Standard Error of Estimate (SEE) of 12 years. The Kappa coefficient value for the intra and inter examiner variability was 0.85 & 0.83 respectively. Our results showed that permanent mandibular 2(nd) molar can be taken as an index tooth for estimating the age of the adults using digitized periapical radiograph and AUTOCAD software. Also high differences were observed between estimated and chronological age of 12 years which is not in the acceptable range. But it provides a new window for research in the forensic sciences in estimating the adult age. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Correcting anthropogenic ocean heat uptake estimates for the Little Ice Age

NASA Astrophysics Data System (ADS)

Gebbie, Geoffrey

2017-04-01

Estimates of anthropogenic ocean heat uptake typically assume that the ocean was in equilibrium during the pre-industrial era. Recent reconstructions of the Common Era, however, show a multi-century surface cooling trend before the Industrial Revolution. Using a time-evolving state estimation method, we find that the 1750 C.E. ocean must have been out of equilibrium in order to fit the H.M.S. Challenger, WOCE, and Argo hydrographic data. When the disequilibrated ocean conditions are taken into account, the inferred ocean heat uptake from 1750-2014 C.E. is revised due to the deep ocean memory of Little Ice Age surface forcing. These effects of ocean disequilibrium should also be considered when interpreting climate sensitivity estimates.

Prevalence estimates for primary brain tumors in the United States by age, gender, behavior, and histology.

PubMed

Porter, Kimberly R; McCarthy, Bridget J; Freels, Sally; Kim, Yoonsang; Davis, Faith G

2010-06-01

Prevalence is the best indicator of cancer survivorship in the population, but few studies have focused on brain tumor prevalence because of previous data limitations. Hence, the full impact of primary brain tumors on the healthcare system in the United States is not completely described. The present study provides an estimate of the prevalence of disease in the United States, updating an earlier prevalence study. Incidence data for 2004 and survival data for 1985-2005 were obtained by the Central Brain Tumor Registry of the United States from selected regions, modeled under 2 different survival assumptions, to estimate prevalence rates for the year 2004 and projected estimates for 2010. The overall incidence rate for primary brain tumors was 18.1 per 100 000 person-years with 2-, 5-, 10-, and 20-year observed survival rates of 62%, 54%, 45%, and 30%, respectively. On the basis of the sum of nonmalignant and averaged malignant estimates, the overall prevalence rate of individuals with a brain tumor was estimated to be 209.0 per 100 000 in 2004 and 221.8 per 100 000 in 2010. The female prevalence rate (264.8 per 100 000) was higher than that in males (158.7 per 100 000). The averaged prevalence rate for malignant tumors (42.5 per 100 000) was lower than the prevalence for nonmalignant tumors (166.5 per 100 000). This study provides estimates of the 2004 (n = 612 770) and 2010 (n = 688 096) expected number of individuals living with primary brain tumor diagnoses in the United States, providing more current and robust estimates for aiding healthcare planning and patient advocacy for an aging US population.

Physiological frailty index (PFI): quantitative in-life estimate of individual biological age in mice.

PubMed

Antoch, Marina P; Wrobel, Michelle; Kuropatwinski, Karen K; Gitlin, Ilya; Leonova, Katerina I; Toshkov, Ilia; Gleiberman, Anatoli S; Hutson, Alan D; Chernova, Olga B; Gudkov, Andrei V

2017-03-19

The development of healthspan-extending pharmaceuticals requires quantitative estimation of age-related progressive physiological decline. In humans, individual health status can be quantitatively assessed by means of a frailty index (FI), a parameter which reflects the scale of accumulation of age-related deficits. However, adaptation of this methodology to animal models is a challenging task since it includes multiple subjective parameters. Here we report a development of a quantitative non-invasive procedure to estimate biological age of an individual animal by creating physiological frailty index (PFI). We demonstrated the dynamics of PFI increase during chronological aging of male and female NIH Swiss mice. We also demonstrated acceleration of growth of PFI in animals placed on a high fat diet, reflecting aging acceleration by obesity and provide a tool for its quantitative assessment. Additionally, we showed that PFI could reveal anti-aging effect of mTOR inhibitor rapatar (bioavailable formulation of rapamycin) prior to registration of its effects on longevity. PFI revealed substantial sex-related differences in normal chronological aging and in the efficacy of detrimental (high fat diet) or beneficial (rapatar) aging modulatory factors. Together, these data introduce PFI as a reliable, non-invasive, quantitative tool suitable for testing potential anti-aging pharmaceuticals in pre-clinical studies.

Third molar mineralization in relation to chronologic age estimation of the Han in central southern China.

PubMed

Liu, Ying; Geng, Kun; Chu, Yanhao; Xu, Mindi; Zha, Lagabaiyila

2018-03-03

The purpose of this study is to provide a forensic reference data about estimating chronologic age by evaluating the third molar mineralization of Han in central southern China. The mineralization degree of third molars was assessed by Demirjian's classification with modification for 2519 digital orthopantomograms (1190 males, 1329 females; age 8-23 years). The mean ages of the initial mineralization and the crown completion of third molars were around 9.66 and 13.88 years old in males and 9.52 and 14.09 years old in females. The minimum ages of apical closure were around 16 years in both sexes. Twenty-eight at stage C and stage G and 38 and 48 at stage F occurred earlier in males than in females. There was no significant difference between maxillary and mandibular teeth in males and females except that stage C in males. Two formulas were devised to estimate age based on mineralization stages and sexes. In Hunan Province, the person will probably be over age 14, when a third molar reaches the stage G. The results of the study could provide reference for age estimation in forensic cases and clinical dentistry.

Estimation of single-year-of-age counts of live births, fetal losses, abortions, and pregnant women for counties of Texas.

PubMed

Singh, Bismark; Meyers, Lauren Ancel

2017-05-08

We provide a methodology for estimating counts of single-year-of-age live-births, fetal-losses, abortions, and pregnant women from aggregated age-group counts. As a case study, we estimate counts for the 254 counties of Texas for the year 2010. We use interpolation to estimate counts of live-births, fetal-losses, and abortions by women of each single-year-of-age for all Texas counties. We then use these counts to estimate the numbers of pregnant women for each single-year-of-age, which were previously available only in aggregate. To support public health policy and planning, we provide single-year-of-age estimates of live-births, fetal-losses, abortions, and pregnant women for all Texas counties in the year 2010, as well as the estimation method source code.

The role of forensic medicine and forensic dentistry in estimating the chronological age of living individuals in Hamburg, Germany.

PubMed

Mansour, Hussam; Fuhrmann, Andreas; Paradowski, Ioana; van Well, Eilin Jopp; Püschel, Klaus

2017-03-01

Age estimation represents one of the primary responsibilities of forensic medicine and forensic dentistry. It is an integral procedure aiming to estimate the chronological age of an individual, whose age is either unknown or doubtful, by means of assessing the stage of dental, skeletal, and physical development. The present publication reviews the methods and procedures used in estimating the age of young living individuals as well as the experiences of the Institute of Legal Medicine in Hamburg-Eppendorf, Germany, during the last 25 years. From 1990 to 2015, 4223 age estimations were carried out in Hamburg. During this time, forensic age estimation was requested by different concerned authorities including courts, the foreigners' registration office (Zentrale Ausländerbehörde), and the state office of education and consultation (Landesbetrieb Erziehung und Beratung). In the context of judicial proceedings, orthopantomograms, as well as X-ray examinations of both the left hand and the medial clavicular epiphyses were carried out in accordance with AGFAD recommendations. For investigations not associated with judicial proceedings, orthopantomogram examinations play a key role in the process of age estimation, due to their high diagnostic value and low radiation exposure. Since 2009, mainly unaccompanied young refugees were examined for age estimation. Orthopantomograms and clinical-physical examinations have been used as essential steps in this context to determine whether an individual is 18 years or less. Additional X-ray examinations of the left hand and the medial clavicular epiphyses have been used less frequently.

Digital radiographic evaluation of mandibular third molar for age estimation in young adults and adolescents of South Indian population using modified Demirjian's method

PubMed Central

Mohammed, Rezwana Begum; Koganti, Ravichandra; Kalyan, Siva V.; Tircouveluri, Saritha; Singh, Johar Rajvinder; Srinivasulu, Enganti

2014-01-01

In recent years, it has become increasingly important to determine the age of living people for a variety of reasons, including identifying criminal and legal responsibility and for many other social events such as birth certificate, marriage, beginning a job, joining the army and retirement Objectives: The aim of this study was to assess the developmental stages of mandibular third molar for estimation of dental age (DA) in different age groups and to evaluate the possible correlation between DA and chronological age (CA) in South Indian population. Materials and Methods: Digital orthopantomography of 330 subjects (165 males, 165 females) who fit the study and the criteria were obtained. Assessment of mandibular third molar development was performed using Demirjian et al., modified method and DA was assessed using tooth specific stages. Results and Discussion: The present study showed a significant correlation between DA and CA in both males and females. Third molar development commenced around 9 years and root completion takes place around 18.9 years in males and in females 9 years and 18.6 years respectively. Demirjian modified method underestimated the mean age of males by 0.8 years and females by 0.5 years and also showed that females mature earlier than males in selected population. Conclusion: Digital radiographic assessment of mandibular third molar development can be used to generate mean DA using Demirjian modified method and also the estimated age range for an individual of unknown CA. Since the Demirjian method is based on French-Canadian population, to enhance the accuracy of forensic age estimates based on third molar development, the use of population-specific standards is recommended. PMID:25177143

The first step toward genetic selection for host tolerance to infectious pathogens: obtaining the tolerance phenotype through group estimates

PubMed Central

Doeschl-Wilson, Andrea B.; Villanueva, Beatriz; Kyriazakis, Ilias

2012-01-01

Reliable phenotypes are paramount for meaningful quantification of genetic variation and for estimating individual breeding values on which genetic selection is based. In this paper, we assert that genetic improvement of host tolerance to disease, although desirable, may be first of all handicapped by the ability to obtain unbiased tolerance estimates at a phenotypic level. In contrast to resistance, which can be inferred by appropriate measures of within host pathogen burden, tolerance is more difficult to quantify as it refers to change in performance with respect to changes in pathogen burden. For this reason, tolerance phenotypes have only been specified at the level of a group of individuals, where such phenotypes can be estimated using regression analysis. However, few stsudies have raised the potential bias in these estimates resulting from confounding effects between resistance and tolerance. Using a simulation approach, we demonstrate (i) how these group tolerance estimates depend on within group variation and co-variation in resistance, tolerance, and vigor (performance in a pathogen free environment); and (ii) how tolerance estimates are affected by changes in pathogen virulence over the time course of infection and by the timing of measurements. We found that in order to obtain reliable group tolerance estimates, it is important to account for individual variation in vigor, if present, and that all individuals are at the same stage of infection when measurements are taken. The latter requirement makes estimation of tolerance based on cross-sectional field data challenging, as individuals become infected at different time points and the individual onset of infection is unknown. Repeated individual measurements of within host pathogen burden and performance would not only be valuable for inferring the infection status of individuals in field conditions, but would also provide tolerance estimates that capture the entire time course of infection. PMID

Modeling mangrove biomass using remote sensing based age and growth estimates

NASA Astrophysics Data System (ADS)

Lagomasino, D.; Fatoyinbo, T. E.; Feliciano, E. A.; Lee, S. K.; Trettin, C.; Mangora, M.; Rahman, M.

2016-12-01

Mangroves are highly regarded coastal forests because of their ecosystem services and high carbon storage potential. In addition, these forests can develop rapidly in locations where congenial environmental conditions and sediment supply are available. Monitoring the growth and age of developing mangrove forests is crucial for sustainable management and estimating carbon stocks. Combining imagery from radar and optical satellites (e.g., TanDEM-X and Landsat), we can estimate young mangrove growth and age at regional and continental scales. We used TanDEM-X radar interferometry for modeling canopy height in 2013 and Landsat to measure land cover change from 1990 to 2013. Annual NDVI composites were determined for each calendar year between 1990 and 2013. New land areas gained from the transition of water to vegetation were determined by the differences in annual NDVI composites and the reference year 2013. The year of the greatest NDVI difference that met the threshold criteria was used as the initial tree height (0 m). Annual canopy height growth rates were estimated by the duration between land generation times and 2013 canopy height models derived from TanDEM-X and very-high resolution optical data. In this presentation, we compare growth rates and biomass accumulation in mangrove forests at four river deltas; the Zambezi (Mozambique), Rufiji (Tanzania), Ganges (Bangladesh), and Mekong (Vietnam). The spatial patterns of growth rates coincided with characteristic successional paradigms and stream morphology, where the maximum growth rates typically occurred along prograding creek banks. Initial comparisons between height-only and growth-age biomass indicate that the latter tend to overestimate biomass for younger forest stands of similar height. Both the vertical (e.g., canopy height) and horizontal (e.g., expansion) growth rates measured from remote sensing can garner important information regarding mangrove succession and primary productivity. Continued research

An Optimal Estimation Method to Obtain Surface Layer Turbulent Fluxes from Profile Measurements

NASA Astrophysics Data System (ADS)

Kang, D.

2015-12-01

In the absence of direct turbulence measurements, the turbulence characteristics of the atmospheric surface layer are often derived from measurements of the surface layer mean properties based on Monin-Obukhov Similarity Theory (MOST). This approach requires two levels of the ensemble mean wind, temperature, and water vapor, from which the fluxes of momentum, sensible heat, and water vapor can be obtained. When only one measurement level is available, the roughness heights and the assumed properties of the corresponding variables at the respective roughness heights are used. In practice, the temporal mean with large number of samples are used in place of the ensemble mean. However, in many situations the samples of data are taken from multiple levels. It is thus desirable to derive the boundary layer flux properties using all measurements. In this study, we used an optimal estimation approach to derive surface layer properties based on all available measurements. This approach assumes that the samples are taken from a population whose ensemble mean profile follows the MOST. An optimized estimate is obtained when the results yield a minimum cost function defined as a weighted summation of all error variance at each sample altitude. The weights are based one sample data variance and the altitude of the measurements. This method was applied to measurements in the marine atmospheric surface layer from a small boat using radiosonde on a tethered balloon where temperature and relative humidity profiles in the lowest 50 m were made repeatedly in about 30 minutes. We will present the resultant fluxes and the derived MOST mean profiles using different sets of measurements. The advantage of this method over the 'traditional' methods will be illustrated. Some limitations of this optimization method will also be discussed. Its application to quantify the effects of marine surface layer environment on radar and communication signal propagation will be shown as well.

Dental age estimation in the living after completion of third molar mineralization: new data for Gustafson's criteria.

PubMed

Timme, M; Timme, W H; Olze, A; Ottow, C; Ribbecke, S; Pfeiffer, H; Dettmeyer, R; Schmeling, A

2017-03-01

There is a need for dental age estimation methods after completion of the third molar mineralization. Degenerative dental characteristics appear to be suitable for forensic age diagnostics beyond the 18th year of life. In 2012, Olze et al. investigated the criteria studied by Gustafson using orthopantomograms. The objective of this study was to prove the applicability and reliability of this method with a large cohort and a wide age range, including older individuals. For this purpose, 2346 orthopantomograms of 1167 female and 1179 male Germans aged 15 to 70 years were reviewed. The characteristics of secondary dentin formation, cementum apposition, periodontal recession and attrition were evaluated in all the mandibular premolars. The correlation of the individual characteristics with the chronological age was examined by means of a stepwise multiple regression analysis, in which the chronological age formed the dependent variable. Following those results, R 2 values amounted to 0.73 to 0.8; the standard error of estimate was 6.8 to 8.2 years. Fundamentally, the recommendation for conducting age estimations in the living by these methods can be shared. The values for the quality of the regression are, however, not precise enough for a reliable age estimation around regular retirement date ages. More precise regression formulae for the age group of 15 to 40 years of life are separately presented in this study. Further research should investigate the influence of ethnicity, dietary habits and modern health care on the degenerative characteristics in question.

Age estimation using pulp/tooth area ratio in maxillary canines-A digital image analysis.

PubMed

Juneja, Manjushree; Devi, Yashoda B K; Rakesh, N; Juneja, Saurabh

2014-09-01

Determination of age of a subject is one of the most important aspects of medico-legal cases and anthropological research. Radiographs can be used to indirectly measure the rate of secondary dentine deposition which is depicted by reduction in the pulp area. In this study, 200 patients of Karnataka aged between 18-72 years were selected for the study. Panoramic radiographs were made and indirectly digitized. Radiographic images of maxillary canines (RIC) were processed using a computer-aided drafting program (ImageJ). The variables pulp/root length (p), pulp/tooth length (r), pulp/root width at enamel-cementum junction (ECJ) level (a), pulp/root width at mid-root level (c), pulp/root width at midpoint level between ECJ level and mid-root level (b) and pulp/tooth area ratio (AR) were recorded. All the morphological variables including gender were statistically analyzed to derive regression equation for estimation of age. It was observed that 2 variables 'AR' and 'b' contributed significantly to the fit and were included in the regression model, yielding the formula: Age = 87.305-480.455(AR)+48.108(b). Statistical analysis indicated that the regression equation with selected variables explained 96% of total variance with the median of the residuals of 0.1614 years and standard error of estimate of 3.0186 years. There is significant correlation between age and morphological variables 'AR' and 'b' and the derived population specific regression equation can be potentially used for estimation of chronological age of individuals of Karnataka origin.

Estimates of the solar internal angular velocity obtained with the Mt. Wilson 60-foot solar tower

NASA Technical Reports Server (NTRS)

Rhodes, Edward J., Jr.; Cacciani, Alessandro; Woodard, Martin; Tomczyk, Steven; Korzennik, Sylvain

1987-01-01

Estimates are obtained of the solar internal angular velocity from measurements of the frequency splittings of p-mode oscillations. A 16-day time series of full-disk Dopplergrams obtained during July and August 1984 at the 60-foot tower telescope of the Mt. Wilson Observatory is analyzed. Power spectra were computed for all of the zonal, tesseral, and sectoral p-modes from l = 0 to 89 and for all of the sectoral p-modes from l = 90 to 200. A mean power spectrum was calculated for each degree up to 89. The frequency differences of all of the different nonzonal modes were calculated for these mean power spectra.

The Demirjian versus the Willems method for dental age estimation in different populations: A meta-analysis of published studies

PubMed Central

2017-01-01

Background The accuracy of radiographic methods for dental age estimation is important for biological growth research and forensic applications. Accuracy of the two most commonly used systems (Demirjian and Willems) has been evaluated with conflicting results. This study investigates the accuracies of these methods for dental age estimation in different populations. Methods A search of PubMed, Scopus, Ovid, Database of Open Access Journals and Google Scholar was undertaken. Eligible studies published before December 28, 2016 were reviewed and analyzed. Meta-analysis was performed on 28 published articles using the Demirjian and/or Willems methods to estimate chronological age in 14,109 children (6,581 males, 7,528 females) age 3–18 years in studies using Demirjian’s method and 10,832 children (5,176 males, 5,656 females) age 4–18 years in studies using Willems’ method. The weighted mean difference at 95% confidence interval was used to assess accuracies of the two methods in predicting the chronological age. Results The Demirjian method significantly overestimated chronological age (p<0.05) in males age 3–15 and females age 4–16 when studies were pooled by age cohorts and sex. The majority of studies using Willems’ method did not report significant overestimation of ages in either sex. Overall, Demirjian’s method significantly overestimated chronological age compared to the Willems method (p<0.05). The weighted mean difference for the Demirjian method was 0.62 for males and 0.72 for females, while that of the Willems method was 0.26 for males and 0.29 for females. Conclusion The Willems method provides more accurate estimation of chronological age in different populations, while Demirjian’s method has a broad application in terms of determining maturity scores. However, accuracy of Demirjian age estimations is confounded by population variation when converting maturity scores to dental ages. For highest accuracy of age estimation, population

The Effects of the Refugee Crisis on Age Estimation Analysis over the Past 10 Years: A 16-Country Survey

PubMed Central

Sykes, Leanne; Bhayat, Ahmed; Bernitz, Herman

2017-01-01

Dental age estimation (AE) tests are routinely done on living and deceased persons. There is anecdotal evidence suggesting an increase in age estimations due to the refugee crisis. Our aim is to determine the reasons and methods for performing dental AE tests in both living and deceased individuals. Global trends in AE over the past 10 years were also investigated. A database of all forensic laboratories was obtained and an electronic questionnaire was sent to all of them. The questionnaire was self-developed and included questions on the reasons for performing AE tests, the preferred methods used in living and deceased individuals, and the people/organizations who requested these AE tests. The number of tests performed annually varied between 0 and 500 and the majority were on asylum seekers, refugees, and for adoption cases. Most units used multiple techniques to determine the age among the living, but seldom used more than three techniques for the deceased. The majority of tests were requested by coroners and the legal fraternity. There has been an increase in the number of dental AEs carried out and this has been mostly due to asylum seekers and refugees. The most common techniques for the living were variations of Demirjian’s technique while country specific techniques were used for the deceased. PMID:28608845

Vitamin C and E Supplements Enhance the Antioxidant Capacity of Erythrocytes Obtained from Aged Rats.

PubMed

Xiong, Yanlian; Xiong, Yanlei; Zhou, Shuai; Sun, Yanan; Zhao, Yuqi; Ren, Xiaotong; Zhang, Yingfang; Zhang, Naili

2017-04-01

The main purpose of the present study was to investigate the effects of vitamin C and E supplements on the antioxidant capacity of erythrocytes obtained from young and aged rats. Male Wistar rats aged 3 and 24 months were used. Vitamins C and E were injected at doses of 200 mg/kg (day) intraperitoneally in young and aged groups. The antioxidant capacity, oxidant stress parameters, and deformability of red blood cells collected from different age stages were evaluated. An in vitro oxidation system was constructed to explore the mechanisms of antioxidant capacity change in the vitamin treatment groups. Treatment with vitamins C and E can effectively restore the antioxidant capacity and deformability of red blood cells (RBCs) in aged rats. Under in vitro oxidative conditions, an age-dependent decline in the influx rate of L-cysteine was observed. This was significantly improved following treatment with vitamins C and E. We present evidence of an improvement in the antioxidant capacity of RBCs by treatment with vitamins C and E in aged rats. These observations also suggest that treatment with vitamins C and E improves glutathione synthesis by enhancing the influx rate of L-cysteine through the modification of membrane proteins and lipids.

A random cluster survey and a convenience sample give comparable estimates of immunity to vaccine preventable diseases in children of school age in Victoria, Australia.

PubMed

Kelly, Heath; Riddell, Michaela A; Gidding, Heather F; Nolan, Terry; Gilbert, Gwendolyn L

2002-08-19

We compared estimates of the age-specific population immunity to measles, mumps, rubella, hepatitis B and varicella zoster viruses in Victorian school children obtained by a national sero-survey, using a convenience sample of residual sera from diagnostic laboratories throughout Australia, with those from a three-stage random cluster survey. When grouped according to school age (primary or secondary school) there was no significant difference in the estimates of immunity to measles, mumps, hepatitis B or varicella. Compared with the convenience sample, the random cluster survey estimated higher immunity to rubella in samples from both primary (98.7% versus 93.6%, P = 0.002) and secondary school students (98.4% versus 93.2%, P = 0.03). Despite some limitations, this study suggests that the collection of a convenience sample of sera from diagnostic laboratories is an appropriate sampling strategy to provide population immunity data that will inform Australia's current and future immunisation policies. Copyright 2002 Elsevier Science Ltd.

Stratigraphy, correlation, and age estimates for fossils from Area 123, Koobi Fora.

PubMed

Feibel, Craig S; Lepre, Christopher J; Quinn, Rhonda L

2009-08-01

Geological data from the Bura Hasuma region at Koobi Fora provide important constraints for estimating the ages of hominin fossils recovered there, including the cranium KNM-ER 1813. Strata of the upper Burgi, KBS, and Okote members in this part of Koobi Fora reflect three depositional regimes driven by changing paleogeography through time. The upper Burgi and lowermost KBS sequence in the southern Bura Hasuma region accumulated in a lacustrine to delta front setting, with highly localized depositional patterns, limiting the lateral extent of lithostratigraphic markers. Farther north, uppermost upper Burgi through KBS member strata document a fluctuating lake margin, with complex facies patterns. This interval is marked by laterally extensive lithostratigraphic markers, including molluscan packstones, beach sandstones, and stromatolite beds. The uppermost KBS and Okote members show a transition to dominantly fluvial character, with localized and discontinuous accumulation. An age model for the richly fossiliferous Area 123 sequence demonstrates the complexity of terrestrial accumulation patterns. Early lacustrine and delta front accumulation is marked by fairly continuous sedimentation, and high accumulation rates (up to ca. 91 cm/k.yr.). The fluctuating lake margin interval reflects lower sedimentation rates coupled with intervals of exposure, decreasing accumulation significantly (to ca. 13 cm/k.yr.). The capping fluvial interval is marked by significant erosion surfaces, breaks which may drop the overall accumulation rate even lower (ca. 0.3 cm/k.yr.). The data provided here establish a geological framework at odds with a recent proposal of ages considerably younger (by ca. 250 k.yr.) for many of the fossils from Area 123 and elsewhere. Tests of age models demonstrate that the younger ages are not possible. While minor refinements to age estimates for fossils are indicated by improved chronostratigraphic control, in the case of KNM-ER 1813, an age of younger

A Simple Method for Estimating Informative Node Age Priors for the Fossil Calibration of Molecular Divergence Time Analyses

PubMed Central

Nowak, Michael D.; Smith, Andrew B.; Simpson, Carl; Zwickl, Derrick J.

2013-01-01

Molecular divergence time analyses often rely on the age of fossil lineages to calibrate node age estimates. Most divergence time analyses are now performed in a Bayesian framework, where fossil calibrations are incorporated as parametric prior probabilities on node ages. It is widely accepted that an ideal parameterization of such node age prior probabilities should be based on a comprehensive analysis of the fossil record of the clade of interest, but there is currently no generally applicable approach for calculating such informative priors. We provide here a simple and easily implemented method that employs fossil data to estimate the likely amount of missing history prior to the oldest fossil occurrence of a clade, which can be used to fit an informative parametric prior probability distribution on a node age. Specifically, our method uses the extant diversity and the stratigraphic distribution of fossil lineages confidently assigned to a clade to fit a branching model of lineage diversification. Conditioning this on a simple model of fossil preservation, we estimate the likely amount of missing history prior to the oldest fossil occurrence of a clade. The likelihood surface of missing history can then be translated into a parametric prior probability distribution on the age of the clade of interest. We show that the method performs well with simulated fossil distribution data, but that the likelihood surface of missing history can at times be too complex for the distribution-fitting algorithm employed by our software tool. An empirical example of the application of our method is performed to estimate echinoid node ages. A simulation-based sensitivity analysis using the echinoid data set shows that node age prior distributions estimated under poor preservation rates are significantly less informative than those estimated under high preservation rates. PMID:23755303

Age Estimation Based on Appearance of Gray Hair in Different Body Sites of Sri Lankan Autopsy Cases.

PubMed

Senanayake, Harshana Mahendra Kumara; Wickramasinghe, Nuwan Darshana

2017-07-01

Owing to the scanty evidence on usefulness of information of appearance of gray hair for age estimation, this study was conducted to estimate age based on the appearance of gray hair on different body sites in a sample of autopsy cases in Sri Lanka. A descriptive cross-sectional study was conducted in Teaching Hospital-Kurunegala during 2011 to 2013. Based on the pattern of the presence of gray hair in different body sites, six stages of gray hair were computed. The analysis 1155 autopsy cases revealed strong, positive correlations between age and appearance of gray hair in head, mustache, beard, and pubic area among males and strong, positive correlations between age and the appearance of gray hair in head and pubic area among females (p < 0.01). Our findings demonstrate the value of information of appearance of gray hair for age estimation in the field of forensic science. © 2016 American Academy of Forensic Sciences.

Aging adult skull remains through radiological density estimates: A comparison of different computed tomography systems and the use of computer simulations to judge the accuracy of results.

PubMed

Obert, Martin; Kubelt, Carolin; Schaaf, Thomas; Dassinger, Benjamin; Grams, Astrid; Gizewski, Elke R; Krombach, Gabriele A; Verhoff, Marcel A

2013-05-10

The objective of this article was to explore age-at-death estimates in forensic medicine, which were methodically based on age-dependent, radiologically defined bone-density (HC) decay and which were investigated with a standard clinical computed tomography (CT) system. Such density decay was formerly discovered with a high-resolution flat-panel CT in the skulls of adult females. The development of a standard CT methodology for age estimations--with thousands of installations--would have the advantage of being applicable everywhere, whereas only few flat-panel prototype CT systems are in use worldwide. A Multi-Slice CT scanner (MSCT) was used to obtain 22,773 images from 173 European human skulls (89 male, 84 female), taken from a population of patients from the Department of Neuroradiology at the University Hospital Giessen and Marburg during 2010 and 2011. An automated image analysis was carried out to evaluate HC of all images. The age dependence of HC was studied by correlation analysis. The prediction accuracy of age-at-death estimates was calculated. Computer simulations were carried out to explore the influence of noise on the accuracy of age predictions. Human skull HC values strongly scatter as a function of age for both sexes. Adult male skull bone-density remains constant during lifetime. Adult female HC decays during lifetime, as indicated by a correlation coefficient (CC) of -0.53. Prediction errors for age-at-death estimates for both of the used scanners are in the range of ±18 years at a 75% confidence interval (CI). Computer simulations indicate that this is the best that can be expected for such noisy data. Our results indicate that HC-decay is indeed present in adult females and that it can be demonstrated both by standard and by high-resolution CT methods, applied to different subject groups of an identical population. The weak correlation between HC and age found by both CT methods only enables a method to estimate age-at-death with limited

USE OF COMMERCIAL TELEPHONE DIRECTORY FOR OBTAINING A POPULATION-BASED SAMPLE OF WOMEN OF REPRODUCTIVE AGE

EPA Science Inventory

Using Commercial Telephone Directories to Obtain a Population-Based Sample for Mail Survey of Women of Reproductive Age

Danelle T. Lobdella, Germaine M. Buckb, John M. Weinerc, Pauline Mendolaa

aUnited States Environmental Protection Agency, Office of Research and ...

Some preliminary estimates of energy utilization in even-aged northern hardwoods

Treesearch

William B. Leak

1970-01-01

Estimates of energy utilization from various sources indicate that even-aged northern hardwood stands utilize less than 1/2 percent of net solar radiation for wood, leaf, and seed production, and only about 1/10 percent for production of merchantable wood. Forest managers should seek to understand and manipulate the remaining 99+ percent of solar energy, for improving...

Computerized Bone Age Estimation Using Deep Learning Based Program: Evaluation of the Accuracy and Efficiency.

PubMed

Kim, Jeong Rye; Shim, Woo Hyun; Yoon, Hee Mang; Hong, Sang Hyup; Lee, Jin Seong; Cho, Young Ah; Kim, Sangki

2017-12-01

The purpose of this study is to evaluate the accuracy and efficiency of a new automatic software system for bone age assessment and to validate its feasibility in clinical practice. A Greulich-Pyle method-based deep-learning technique was used to develop the automatic software system for bone age determination. Using this software, bone age was estimated from left-hand radiographs of 200 patients (3-17 years old) using first-rank bone age (software only), computer-assisted bone age (two radiologists with software assistance), and Greulich-Pyle atlas-assisted bone age (two radiologists with Greulich-Pyle atlas assistance only). The reference bone age was determined by the consensus of two experienced radiologists. First-rank bone ages determined by the automatic software system showed a 69.5% concordance rate and significant correlations with the reference bone age (r = 0.992; p < 0.001). Concordance rates increased with the use of the automatic software system for both reviewer 1 (63.0% for Greulich-Pyle atlas-assisted bone age vs 72.5% for computer-assisted bone age) and reviewer 2 (49.5% for Greulich-Pyle atlas-assisted bone age vs 57.5% for computer-assisted bone age). Reading times were reduced by 18.0% and 40.0% for reviewers 1 and 2, respectively. Automatic software system showed reliably accurate bone age estimations and appeared to enhance efficiency by reducing reading times without compromising the diagnostic accuracy.

Comparison of parental estimate of developmental age with measured IQ in children with neurodevelopmental disorders.

PubMed

Chandler, S; Howlin, P; Simonoff, E; Kennedy, J; Baird, G

2016-07-01

Formal IQ tests are an important part of the diagnostic and needs-based assessment process for children with neurodevelopmental disorders. However, resources for such assessments are not always available. It has been suggested that parental estimates of their child's developmental age could serve as a proxy IQ when formal measures are unavailable. Parental estimates of their child's developmental age were converted to a developmental quotient (DQ) in 197 children with Autism Spectrum Disorder (ASD) aged 4-9 years, and 108 children with ADHD and intellectual disability (ADHD + ID) aged 7-15 years. Formal IQ assessments were then conducted. Parents completed the Social Communication Questionnaire ((SCQ), a measure of autism symptomatology) and a demographic questionnaire. In the ASD sample, 58% of parent estimates were within 15 points (i.e. one standard deviation) of the child's measured IQ score. Lower measured IQ and lower SCQ total score predicted higher parental accuracy. In the ADHD + ID sample, 74% of parental estimates were within 15 points of measured IQ. In this group, higher child IQ predicted greater parental accuracy. Parents in the ADHD + ID group were more likely to overestimate children's ability level than parents in the ASD group. In this study, the majority of parents of children with ADHD and ID were able to estimate their child's intellectual ability level with some accuracy. Parents of children with ASD were less accurate, but this may be because these parents were focussing more on children's level of adaptive functioning, which is known to be typically lower than cognitive ability in ASD. © 2016 John Wiley & Sons Ltd.

Otolith reading and multi-model inference for improved estimation of age and growth in the gilthead seabream Sparus aurata (L.)

NASA Astrophysics Data System (ADS)

Mercier, Lény; Panfili, Jacques; Paillon, Christelle; N'diaye, Awa; Mouillot, David; Darnaude, Audrey M.

2011-05-01

Accurate knowledge of fish age and growth is crucial for species conservation and management of exploited marine stocks. In exploited species, age estimation based on otolith reading is routinely used for building growth curves that are used to implement fishery management models. However, the universal fit of the von Bertalanffy growth function (VBGF) on data from commercial landings can lead to uncertainty in growth parameter inference, preventing accurate comparison of growth-based history traits between fish populations. In the present paper, we used a comprehensive annual sample of wild gilthead seabream ( Sparus aurata L.) in the Gulf of Lions (France, NW Mediterranean) to test a methodology improving growth modelling for exploited fish populations. After validating the timing for otolith annual increment formation for all life stages, a comprehensive set of growth models (including VBGF) were fitted to the obtained age-length data, used as a whole or sub-divided between group 0 individuals and those coming from commercial landings (ages 1-6). Comparisons in growth model accuracy based on Akaike Information Criterion allowed assessment of the best model for each dataset and, when no model correctly fitted the data, a multi-model inference (MMI) based on model averaging was carried out. The results provided evidence that growth parameters inferred with VBGF must be used with high caution. Hence, VBGF turned to be among the less accurate for growth prediction irrespective of the dataset and its fit to the whole population, the juvenile or the adult datasets provided different growth parameters. The best models for growth prediction were the Tanaka model, for group 0 juveniles, and the MMI, for the older fish, confirming that growth differs substantially between juveniles and adults. All asymptotic models failed to correctly describe the growth of adult S. aurata, probably because of the poor representation of old individuals in the dataset. Multi

Twins and the paradox of dental-age estimations: a caution for researchers and clinicians.

PubMed

Pechníková, M; De Angelis, D; Gibelli, D; Vecchio, V; Cameriere, R; Zeqiri, B; Cattaneo, C

2014-08-01

The biological age difference among twins is frequently an issue in studies of genetic influence on various dental features, particularly dental development. The timing of dental development is a crucial issue also for many clinicians and researchers. The aim of this study was therefore to verify within groups of twins how dental development differs, by applying Demirjian's method, Mincer's charts of development of third molars and two of Cameriere's methods for dental age estimation, which are among the most popular methods both in the clinical and the forensic scenario. The sample consisted of 64 twin pairs: 21 monozygotic, 30 dizygotic same-sex and 13 dizygotic opposite-sex with an age range between 5.8 and 22.6 years. Dental age was determined from radiographs using the mentioned methods. Results showed that dental age of monozygotic twins is not identical even if they share all their genes. The mean intra-pair difference of monozygotic pairs was low and similar to the difference in dizygotic same-sex twins; the maximum difference between monozygotic twins, however, was surprisingly large (nearly two years). This should lead to some circumspection in the interpretation of systematic estimations of dental age both in the clinical and forensic scenario. Copyright © 2014 Elsevier GmbH. All rights reserved.

An empirical comparative study on biological age estimation algorithms with an application of Work Ability Index (WAI).

PubMed

Cho, Il Haeng; Park, Kyung S; Lim, Chang Joo

2010-02-01

In this study, we described the characteristics of five different biological age (BA) estimation algorithms, including (i) multiple linear regression, (ii) principal component analysis, and somewhat unique methods developed by (iii) Hochschild, (iv) Klemera and Doubal, and (v) a variant of Klemera and Doubal's method. The objective of this study is to find the most appropriate method of BA estimation by examining the association between Work Ability Index (WAI) and the differences of each algorithm's estimates from chronological age (CA). The WAI was found to be a measure that reflects an individual's current health status rather than the deterioration caused by a serious dependency with the age. Experiments were conducted on 200 Korean male participants using a BA estimation system developed principally under the concept of non-invasive, simple to operate and human function-based. Using the empirical data, BA estimation as well as various analyses including correlation analysis and discriminant function analysis was performed. As a result, it had been confirmed by the empirical data that Klemera and Doubal's method with uncorrelated variables from principal component analysis produces relatively reliable and acceptable BA estimates. 2009 Elsevier Ireland Ltd. All rights reserved.

Systematic feature selection improves accuracy of methylation-based forensic age estimation in Han Chinese males.

PubMed

Feng, Lei; Peng, Fuduan; Li, Shanfei; Jiang, Li; Sun, Hui; Ji, Anquan; Zeng, Changqing; Li, Caixia; Liu, Fan

2018-03-23

Estimating individual age from biomarkers may provide key information facilitating forensic investigations. Recent progress has shown DNA methylation at age-associated CpG sites as the most informative biomarkers for estimating the individual age of an unknown donor. Optimal feature selection plays a critical role in determining the performance of the final prediction model. In this study we investigate methylation levels at 153 age-associated CpG sites from 21 previously reported genomic regions using the EpiTYPER system for their predictive power on individual age in 390 Han Chinese males ranging from 15 to 75 years of age. We conducted a systematic feature selection using a stepwise backward multiple linear regression analysis as well as an exhaustive searching algorithm. Both approaches identified the same subset of 9 CpG sites, which in linear combination provided the optimal model fitting with mean absolute deviation (MAD) of 2.89 years of age and explainable variance (R 2 ) of 0.92. The final model was validated in two independent Han Chinese male samples (validation set 1, N = 65, MAD = 2.49, R 2  = 0.95, and validation set 2, N = 62, MAD = 3.36, R 2  = 0.89). Other competing models such as support vector machine and artificial neural network did not outperform the linear model to any noticeable degree. The validation set 1 was additionally analyzed using Pyrosequencing technology for cross-platform validation and was termed as validation set 3. Directly applying our model, in which the methylation levels were detected by the EpiTYPER system, to the data from pyrosequencing technology showed, however, less accurate results in terms of MAD (validation set 3, N = 65 Han Chinese males, MAD = 4.20, R 2  = 0.93), suggesting the presence of a batch effect between different data generation platforms. This batch effect could be partially overcome by a z-score transformation (MAD = 2.76, R 2  = 0.93). Overall, our

Limitations of backward integration method for asteroid family age estimation

NASA Astrophysics Data System (ADS)

Radović, Viktor

2017-10-01

Determining the age of an asteroid family is important as it gives us a better understanding of the dynamics, formation and collisional evolution of a family. So far, a few methods for determining the age of a family have been developed. The most accurate one is probably the backward integration method (BIM) that works very well for young families. In this paper, we try to study its characteristics and limitations in more detail using a fictional asteroid family. The analysis is performed with two numerical packages: orbfit and mercury. We studied the clustering of the secular angles Ω and ϖ and obtained linear relationship between the depth of the clustering and the age of the family. Our results suggest that the BIM could be successfully applied only to families not older than 18 Myr.

A person trade-off study to estimate age-related weights for health gains in economic evaluation.

PubMed

Petrou, Stavros; Kandala, Ngianga-Bakwin; Robinson, Angela; Baker, Rachel

2013-10-01

An increasing body of literature is exploring whether the age of the recipient of health care should be a criterion in how health care resources are allocated. The existing literature is constrained both by the relatively small number of age comparison groups within preference-elicitation studies, and by a paucity of methodological robustness tests for order and framing effects and the reliability and transitivity of preferences that would strengthen confidence in the results. This paper reports the results of a study aimed at estimating granulated age-related weights for health gains across the age spectrum that can potentially inform health care decision-making. A sample of 2,500 participants recruited from the health care consumer panels of a social research company completed a person trade-off (or 'matching') study designed to estimate age-related weights for 5- and 10-year life extensions. The results are presented in terms of matrices for alternative age comparisons across the age spectrum. The results revealed a general, although not invariable, tendency to give more weight to health gains, expressed in terms of life extensions, in younger age groups. In over 85% of age comparisons, the person trade-off exercises revealed a preference for life extensions by the younger of the two age groups that were compared. This pattern held regardless of the method of aggregating responses across study participants. Moreover, the relative weight placed on life extensions by the younger of the two age groups was generally, although not invariably, found to increase as the age difference between the comparator age groups increased. Further analyses revealed that the highest mean relative weight placed on life extensions was estimated for 30-year-olds when the ratio of means method was used to aggregate person trade-off responses across study participants. The highest mean relative weight placed on life extensions was estimated for 10-year-olds for 5-year life extensions

Walleye age estimation using otoliths and dorsal spines: Preparation techniques and sampling guidelines based on sex and total length

USGS Publications Warehouse

Dembkowski, Daniel J.; Isermann, Daniel A.; Koenigs, Ryan P.

2017-01-01

We used dorsal spines and otoliths from 735 Walleye Sander vitreus collected from 35 Wisconsin water bodies to evaluate whether 1) otolith and dorsal spine cross sections provided age estimates similar to simpler methods of preparation (e.g., whole otoliths and dorsal spines, cracked otoliths); and 2) between-reader precision and differences between spine and otolith ages varied in relation to total length (TL), sex, and growth rate. Ages estimated from structures prepared using simpler techniques were generally similar to ages estimated using thin sections of dorsal spines and otoliths, suggesting that, in some instances, much of the additional processing time and specialized equipment associated with thin sectioning could be avoided. Overall, between-reader precision was higher for sectioned otoliths (mean coefficient of variation [CV] = 3.28%; standard error [SE] = 0.33%) than for sectioned dorsal spines (mean CV = 9.20%; SE = 0.56%). When using sectioned otoliths for age assignment, between-reader precision did not vary between sexes or growth categories (i.e., fast, moderate, slow), but between-reader precision was higher for females than males when using sectioned dorsal spines. Dorsal spines were generally effective at replicating otolith ages for male Walleye <450 mm TL and female Walleye <600 mm TL, suggesting that dorsal spines can be used to estimate ages for male Walleye <450 mm TL and female Walleye <600 mm TL. If sex is unknown, we suggest dorsal spines be used to estimate ages for Walleye <450 mm TL, but that otoliths be used for fish >450 mm TL. Our results provide useful guidance on structure and preparation technique selection for Walleye age estimation, thereby allowing biologists to develop sampling guidelines that could be implemented using information that is always (TL) or often (sex) available at the time of fish collection.

An elusive paleodemography? A comparison of two methods for estimating the adult age distribution of deaths at late Classic Copan, Honduras.

PubMed

Storey, Rebecca

2007-01-01

Comparison of different adult age estimation methods on the same skeletal sample with unknown ages could forward paleodemographic inference, while researchers sort out various controversies. The original aging method for the auricular surface (Lovejoy et al., 1985a) assigned an age estimation based on several separate characteristics. Researchers have found this original method hard to apply. It is usually forgotten that before assigning an age, there was a seriation, an ordering of all available individuals from youngest to oldest. Thus, age estimation reflected the place of an individual within its sample. A recent article (Buckberry and Chamberlain, 2002) proposed a revised method that scores theses various characteristics into age stages, which can then be used with a Bayesian method to estimate an adult age distribution for the sample. Both methods were applied to the adult auricular surfaces of a Pre-Columbian Maya skeletal population from Copan, Honduras and resulted in age distributions with significant numbers of older adults. However, contrary to the usual paleodemographic distribution, one Bayesian estimation based on uniform prior probabilities yielded a population with 57% of the ages at death over 65, while another based on a high mortality life table still had 12% of the individuals aged over 75 years. The seriation method yielded an age distribution more similar to that known from preindustrial historical situations, without excessive longevity of adults. Paleodemography must still wrestle with its elusive goal of accurate adult age estimation from skeletons, a necessary base for demographic study of past populations. (c) 2006 Wiley-Liss, Inc

Extreme longevity in freshwater mussels revisited: sources of bias in age estimates derived from mark-recapture experiments

Treesearch

Wendell R. Haag

2009-01-01

There may be bias associated with mark–recapture experiments used to estimate age and growth of freshwater mussels. Using subsets of a mark–recapture dataset for Quadrula pustulosa, I examined how age and growth parameter estimates are affected by (i) the range and skew of the data and (ii) growth reduction due to handling. I compared predictions...

Estimation of submarine mass failure probability from a sequence of deposits with age dates

USGS Publications Warehouse

Geist, Eric L.; Chaytor, Jason D.; Parsons, Thomas E.; ten Brink, Uri S.

2013-01-01

The empirical probability of submarine mass failure is quantified from a sequence of dated mass-transport deposits. Several different techniques are described to estimate the parameters for a suite of candidate probability models. The techniques, previously developed for analyzing paleoseismic data, include maximum likelihood and Type II (Bayesian) maximum likelihood methods derived from renewal process theory and Monte Carlo methods. The estimated mean return time from these methods, unlike estimates from a simple arithmetic mean of the center age dates and standard likelihood methods, includes the effects of age-dating uncertainty and of open time intervals before the first and after the last event. The likelihood techniques are evaluated using Akaike’s Information Criterion (AIC) and Akaike’s Bayesian Information Criterion (ABIC) to select the optimal model. The techniques are applied to mass transport deposits recorded in two Integrated Ocean Drilling Program (IODP) drill sites located in the Ursa Basin, northern Gulf of Mexico. Dates of the deposits were constrained by regional bio- and magnetostratigraphy from a previous study. Results of the analysis indicate that submarine mass failures in this location occur primarily according to a Poisson process in which failures are independent and return times follow an exponential distribution. However, some of the model results suggest that submarine mass failures may occur quasiperiodically at one of the sites (U1324). The suite of techniques described in this study provides quantitative probability estimates of submarine mass failure occurrence, for any number of deposits and age uncertainty distributions.

Anchoring the Population II Distance Scale: Accurate Ages for Globular Clusters

NASA Technical Reports Server (NTRS)

Chaboyer, Brian C.; Chaboyer, Brian C.; Carney, Bruce W.; Latham, David W.; Dunca, Douglas; Grand, Terry; Layden, Andy; Sarajedini, Ataollah; McWilliam, Andrew; Shao, Michael

2004-01-01

The metal-poor stars in the halo of the Milky Way galaxy were among the first objects formed in our Galaxy. These Population II stars are the oldest objects in the universe whose ages can be accurately determined. Age determinations for these stars allow us to set a firm lower limit, to the age of the universe and to probe the early formation history of the Milky Way. The age of the universe determined from studies of Population II stars may be compared to the expansion age of the universe and used to constrain cosmological models. The largest uncertainty in estimates for the ages of stars in our halo is due to the uncertainty in the distance scale to Population II objects. We propose to obtain accurate parallaxes to a number of Population II objects (globular clusters and field stars in the halo) resulting in a significant improvement in the Population II distance scale and greatly reducing the uncertainty in the estimated ages of the oldest stars in our galaxy. At the present time, the oldest stars are estimated to be 12.8 Gyr old, with an uncertainty of approx. 15%. The SIM observations obtained by this key project, combined with the supporting theoretical research and ground based observations outlined in this proposal will reduce the estimated uncertainty in the age estimates to 5%).

Estimating the age of oil palm trees using remote sensing technique

NASA Astrophysics Data System (ADS)

Fitrianto, A. C.; Darmawan, A.; Tokimatsu, K.; Sufwandika, M.

2018-04-01

One of renewable energy that can be converted into electricity is biomass. Biomass energy or bio energy is the largest source of domestic renewable energy in Indonesia. Since palm oil development is rapidly increasing, Empty Fruit Bunch (EFB) and Mesocarp Fiber (MF) are becoming the highest contributor of oil palm waste. Understanding biomass waste potential is very important for further utilization. Remote sensing technique can be used to detect oil palm trees age based on the canopy density and to estimate the amount of EFB in further analysis. In this research, the percentage of canopy density of oil palm trees/stands depends on their ages and the age is divided into four classes; seeds (<3 years old; <10%), young (3-8 years old; 10-40 %), teenage (9-14 years old; 41-80 %), and mature (15-25 years old; >80 %).

Menstrual versus clinical estimate of gestational age dating in the United States: temporal trends and variability in indices of perinatal outcomes.

PubMed

Ananth, Cande V

2007-09-01

Accurate estimation of gestational age early in pregnancy is paramount for obstetric care decisions and for determining fetal growth and other conditions that may necessitate timing the iatrogenic intervention or delivery. We sought to examine temporal changes in the distributions of two measures of gestational age, namely, those based on menstrual dating and a clinical estimate. We further sought to evaluate relative comparisons and variability in indices of perinatal outcomes. We utilised the Natality data files in the US, 1990-2002 comprising women that delivered a singleton livebirth between 22 and 44 weeks gestation (n = 42 689 603). Changes were shown in the distributions of gestational age based on menstrual vs. clinical estimate between 1990 and 2002, as well as changes in the proportions of preterm (<37, <32 and <28 weeks) and post-term (>or=42 weeks) birth, and small- (SGA; <10th percentile) and large-for-gestational-age (LGA; birthweight >90th percentile) births. While the absolute rates of preterm birth <37 weeks, SGA and LGA births were lower based on the clinical estimate of gestational age relative to that based on menstrual dating, the increases in preterm birth rate between 1990 and 2002 were fairly similar between the two measures of gestational dating. However, the decline in post-term births was larger, based on the clinical estimate (-73.8%), than on the menstrual estimate (-36.6%) between 1990 and 2002. While the clinical estimate of gestational age appears to provide a reasonably good approximation to the menstrual estimate, disregarding the clinical estimate of gestational age may ignore the advantages of gestational age assessment in modern obstetrics.

Estimated incidence of pertussis in people aged <50 years in the United States

PubMed Central

Chen, Chi-Chang; Balderston McGuiness, Catherine; Krishnarajah, Girishanthy; Blanchette, Christopher M.; Wang, Yuanyuan; Sun, Kainan; Buck, Philip O.

2016-01-01

ABSTRACT The introduction of pertussis vaccination in the United States (US) in the 1940s has greatly reduced its burden. However, the incidence of pertussis is difficult to quantify, as many cases are not laboratory-confirmed or reported, particularly in adults. This study estimated pertussis incidence in a commercially insured US population aged <50 years. Data were extracted from IMS' PharMetrics Plus claims database for patients with a diagnosis of pertussis or cough illness using International Classification of Diseases (ICD-9) codes, a commercial outpatient laboratory database for patients with a pertussis laboratory test, and the Centers for Disease Control influenza surveillance database. US national pertussis incidence was projected using 3 methods: (1) diagnosed pertussis, defined as a claim for pertussis (ICD-9 033.0, 033.9, 484.3) during 2008–2013; (2) based on proxy pertussis predictive logistic regression models; (3) using the fraction of cough illness (ICD-9 033.0, 033.9, 484.3, 786.2, 466.0, 466.1, 487.1) attributed to laboratory-confirmed pertussis, estimated by time series linear regression models. Method 1 gave a projected annual incidence of diagnosed pertussis of 9/100,000, which was highest in those aged <1 year. Method 2 gave an average annual projected incidence of 21/100,000. Method 3 gave an overall regression-estimated weighted annual incidence of pertussis of 649/100,000, approximately 58–93 times higher than method 1 depending on the year. These estimations, which are consistent with considerable underreporting of pertussis in people aged <50 years and provide further evidence that the majority of cases go undetected, especially with increasing age, may aid in the development of public health programs to reduce pertussis burden. PMID:27246119

[Problems associated with age estimation of underage persons who appear in child pornography materials].

PubMed

Łabecka, Marzena; Lorkiewicz-Muszyńska, Dorota; Jarzabek-Bielecka, Grazyna

2011-01-01

Among opinions issued by the Forensic Medicine Department, Medical Science University in Poznan, in the last six years, there are opinions concerning age estimation in child pornography materials. The issue subject to research is indicating persons under the age of 15 years in pornographic materials, since possession of pornographic materials featuring underage persons is considered a crime and is subject to article 202 of the Penal Code. The estimation of the age of teenagers based on secondary and tertiary sexual characteristics is increasingly more difficult and the available data in professional literature regarding the standard time of development differ among various authors of such studies. In the report, an attempt has been made at determining the agreement regarding different characteristics in the data included in the Tanner's scale, which has been modified to accommodate the research done on persons registered by electronic means. The modified scale, which up to now has been used in research of registered subjects in classified public prosecutors' materials, has been employed in children seen in a pediatric outpatient department. The goal has been a comparison of the outcome of the research to prove its usefulness so that in the future, the modified scale could be used as a research tool in estimation of age of persons appearing in pornography materials. medical forms of 205 children seen in a pediatric outpatient department, based on the scale created by the present authors us and later processed using Excel.

Estimating demographic contributions to effective population size in an age-structured wild population experiencing environmental and demographic stochasticity.

PubMed

Trask, Amanda E; Bignal, Eric M; McCracken, Davy I; Piertney, Stuart B; Reid, Jane M

2017-09-01

A population's effective size (N e ) is a key parameter that shapes rates of inbreeding and loss of genetic diversity, thereby influencing evolutionary processes and population viability. However, estimating N e , and identifying key demographic mechanisms that underlie the N e to census population size (N) ratio, remains challenging, especially for small populations with overlapping generations and substantial environmental and demographic stochasticity and hence dynamic age-structure. A sophisticated demographic method of estimating N e /N, which uses Fisher's reproductive value to account for dynamic age-structure, has been formulated. However, this method requires detailed individual- and population-level data on sex- and age-specific reproduction and survival, and has rarely been implemented. Here, we use the reproductive value method and detailed demographic data to estimate N e /N for a small and apparently isolated red-billed chough (Pyrrhocorax pyrrhocorax) population of high conservation concern. We additionally calculated two single-sample molecular genetic estimates of N e to corroborate the demographic estimate and examine evidence for unobserved immigration and gene flow. The demographic estimate of N e /N was 0.21, reflecting a high total demographic variance (σ2dg) of 0.71. Females and males made similar overall contributions to σ2dg. However, contributions varied among sex-age classes, with greater contributions from 3 year-old females than males, but greater contributions from ≥5 year-old males than females. The demographic estimate of N e was ~30, suggesting that rates of increase of inbreeding and loss of genetic variation per generation will be relatively high. Molecular genetic estimates of N e computed from linkage disequilibrium and approximate Bayesian computation were approximately 50 and 30, respectively, providing no evidence of substantial unobserved immigration which could bias demographic estimates of N e . Our analyses identify

Comparison of internal dose estimates obtained using organ-level, voxel S value, and Monte Carlo techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grimes, Joshua, E-mail: grimes.joshua@mayo.edu; Celler, Anna

2014-09-15

Purpose: The authors’ objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-specific anatomy on the final dose estimate. Methods: Six patients injected with{sup 99m}Tc-hydrazinonicotinamide-Tyr{sup 3}-octreotide were included in this study. A hybrid planar/SPECT imaging protocol was used to estimate {sup 99m}Tc time-integrated activity coefficients (TIACs) for kidneys, liver, spleen, and tumors. Additionally, TIACs were predicted for {sup 131}I, {sup 177}Lu, and {sup 90}Y assuming themore » same biological half-lives as the {sup 99m}Tc labeled tracer. The TIACs were used as input for OLINDA/EXM for organ-level dose calculation and voxel level dosimetry was performed using the voxel S value method and Monte Carlo simulation. Dose estimates for {sup 99m}Tc, {sup 131}I, {sup 177}Lu, and {sup 90}Y distributions were evaluated by comparing (i) organ-level S values corresponding to each method, (ii) total tumor and organ doses, (iii) differences in right and left kidney doses, and (iv) voxelized dose distributions calculated by Monte Carlo and the voxel S value technique. Results: The S values for all investigated radionuclides used by OLINDA/EXM and the corresponding patient-specific S values calculated by Monte Carlo agreed within 2.3% on average for self-irradiation, and differed by as much as 105% for cross-organ irradiation. Total organ doses calculated by OLINDA/EXM and the voxel S value technique agreed with Monte Carlo results within approximately ±7%. Differences between right and left kidney doses determined by Monte Carlo were as high as 73%. Comparison of the Monte Carlo and voxel S value dose distributions showed that each method produced similar dose volume histograms with a minimum dose covering 90% of the volume

An examination of healthy aging across a conceptual continuum: prevalence estimates, demographic patterns, and validity.

PubMed

McLaughlin, Sara J; Jette, Alan M; Connell, Cathleen M

2012-06-01

Although the notion of healthy aging has gained wide acceptance in gerontology, measuring the phenomenon is challenging. Guided by a prominent conceptualization of healthy aging, we examined how shifting from a more to less stringent definition of healthy aging influences prevalence estimates, demographic patterns, and validity. Data are from adults aged 65 years and older who participated in the Health and Retirement Study. We examined four operational definitions of healthy aging. For each, we calculated prevalence estimates and examined the odds of healthy aging by age, education, gender, and race-ethnicity in 2006. We also examined the association between healthy aging and both self-rated health and death. Across definitions, the prevalence of healthy aging ranged from 3.3% to 35.5%. For all definitions, those classified as experiencing healthy aging had lower odds of fair or poor self-rated health and death over an 8-year period. The odds of being classified as "healthy" were lower among those of advanced age, those with less education, and women than for their corresponding counterparts across all definitions. Moving across the conceptual continuum--from a more to less rigid definition of healthy aging--markedly increases the measured prevalence of healthy aging. Importantly, results suggest that all examined definitions identified a subgroup of older adults who had substantially lower odds of reporting fair or poor health and dying over an 8-year period, providing evidence of the validity of our definitions. Conceptualizations that emphasize symptomatic disease and functional health may be particularly useful for public health purposes.

A comparison of LMP-based and ultrasound-based estimates of gestational age using linked California livebirth and prenatal screening records.

PubMed

Dietz, Patricia M; England, Lucinda J; Callaghan, William M; Pearl, Michelle; Wier, Megan L; Kharrazi, Martin

2007-09-01

Although early ultrasound (<20 weeks' gestation) systematically underestimates the gestational age of smaller fetuses by approximately 1-2 days, this bias is relatively small compared with the large error introduced by last menstrual period (LMP) estimates of gestation, as evidenced by the number of implausible birthweight-for-gestational age. To characterise this misclassification, we compared gestational age estimates based on LMP from California birth certificates with those based on early ultrasound from a California linked Statewide Expanded Alpha-fetoprotein Screening Program (XAFP). The final sample comprised 165 908 women. Birthweight distributions were plotted by gestational age; sensitivity and positive predictive value for preterm rates according to LMP were calculated using ultrasound as the 'gold standard'. For gestational ages 20-27 and 28-31 weeks, the LMP-based birthweight distributions were bimodal, whereas the ultrasound-based distributions were unimodal, but had long right tails. At 32-36 weeks, the LMP distribution was wider, flatter, and shifted to the right, compared with the ultrasound distribution. LMP vs. ultrasound estimates were, respectively, 8.7% vs. 7.9% preterm (<37 weeks), 81.2% vs. 91.0% term (37-41 weeks), and 10.1% vs. 1.1% post-term (>or=42 weeks). The sensitivity of the LMP-based preterm birth estimate was 64.3%, and the positive predictive value was 58.7%. Overall, 17.2% of the records had estimates with an absolute difference of >14 days. The groups most likely to have inconsistent gestational age estimates included African American and Hispanic women, younger and less-educated women, and those who entered prenatal care after the second month of pregnancy. In conclusion, we found substantial misclassification of LMP-based gestational age. The 2003 revised US Standard Certificate of Live Birth includes a new gestational age item, the obstetric estimate. It will be important to assess whether this estimate addresses the problems

Optimal dental age estimation practice in United Arab Emirates' children.

PubMed

Altalie, Salem; Thevissen, Patrick; Fieuws, Steffen; Willems, Guy

2014-03-01

The aim of the study was to detect whether the Willems model, developed on a Belgian reference sample, can be used for age estimations in United Arab Emirates (UAE) children. Furthermore, it was verified that if added third molars development information in children provided more accurate age predictions. On 1900 panoramic radiographs, the development of left mandibular permanent teeth (PT) and third molars (TM) was registered according the Demirjian and the Kohler technique, respectively. The PT data were used to verify the Willems model and to develop a UAE model and to verify it. Multiple regression models with PT, TM, and PT + TM scores as independent and age as dependent factor were developed. Comparing the verified Willems- and the UAE model revealed differences in mean error of -0.01 year, mean absolute error of 0.01 year and root mean squared error of 0.90 year. Neglectable overall decrease in RMSE was detected combining PM and TM developmental information. © 2013 American Academy of Forensic Sciences.

Comparison between Greulich-Pyle and Girdany-Golden methods for estimating skeletal age of children in Pakistan.

PubMed

Awais, Muhammad; Nadeem, Naila; Husen, Yousuf; Rehman, Abdul; Beg, Madiha; Khattak, Yasir Jamil

2014-12-01

To compare Greulich-Pyle (GP) and Girdany-Golden (GG) methods for estimation of Skeletal Age (SA) in children referred to a tertiary care hospital in Karachi, Pakistan. Cross-sectional study. Department of Radiology, The Aga Khan University Hospital, Karachi, Pakistan, from July 2010 to June 2012. Children up to the age of 18 years, who had undergone X-ray for the evaluation of trauma were included. Each X-ray was interpreted using both methods by two consultant paediatric radiologists having at least 10 years experience, who were blinded to the actual Chronologic Age (CA) of children. A total of 283 children were included. No significant difference was noted in mean SA estimated by GP method and mean CA for female children (p=0.695). However, a significant difference was noted between mean CA and mean SA by GG method for females (p=0.011). For males, there was a significant difference between mean CA and mean SA estimated by both GP and GG methods. A stronger correlation was found between CA and SA estimated by GP method (r=0.943 for girls, r=0.915 for boys) as compared to GG method (r=0.909 for girls, r=0.865 for boys) respectively. Bland- Altman analysis also revealed that the two methods cannot be used interchangeably. Excellent correlation was seen between the two readers for both GP and GG methods. There was no additional benefit of using GP and GG methods simultaneously over using GP method alone. Moreover, although GP was reliable in estimating SA in girls, it was unable to accurately assess SA in boys. Therefore, it would be ideal to develop indigenous standards of bone age estimation based on a representative sample of healthy native children.

Age and growth of round gobies in Lake Michigan, with preliminary mortality estimation

USGS Publications Warehouse

Huo, Bin; Madenjian, Charles P.; Xie, Cong X.; Zhao, Yingming; O'Brien, Timothy P.; Czesny, Sergiusz J.

2015-01-01

The round goby (Neogobius melanostomus) is a prevalent invasive species throughout Lake Michigan, as well as other Laurentian Great Lakes, yet little information is available on spatial variation in round goby growth within one body of water. Age and growth of round goby at three areas of Lake Michigan were studied by otolith analysis from a sample of 659 specimens collected from 2008 to 2012. Total length (TL) ranged from 48 to 131 mm for Sturgeon Bay, from 50 to 125 mm for Waukegan, and from 54 to 129 mm for Sleeping Bear Dunes. Ages ranged from 2 to 7 years for Sturgeon Bay, from 2 to 5 years for Waukegan, and from 2 to 6 years for Sleeping Bear Dunes. Area-specific and sex-specific body–otolith relationships were used to back-calculate estimates of total length at age, which were fitted to von Bertalanffy models to estimate growth rates. For both sexes, round gobies at Sleeping Bear Dunes and Waukegan grew significantly faster than those at Sturgeon Bay. However, round goby growth did not significantly differ between Sleeping Bear Dunes and Waukegan for either sex. At all three areas of Lake Michigan, males grew significantly faster than females. Based on catch curve analysis, estimates of annual mortality rates ranged from 0.79 to 0.84. These relatively high mortality rates suggested that round gobies may be under predatory control in Lake Michigan.

An iterative procedure for obtaining maximum-likelihood estimates of the parameters for a mixture of normal distributions

NASA Technical Reports Server (NTRS)

Peters, B. C., Jr.; Walker, H. F.

1978-01-01

This paper addresses the problem of obtaining numerically maximum-likelihood estimates of the parameters for a mixture of normal distributions. In recent literature, a certain successive-approximations procedure, based on the likelihood equations, was shown empirically to be effective in numerically approximating such maximum-likelihood estimates; however, the reliability of this procedure was not established theoretically. Here, we introduce a general iterative procedure, of the generalized steepest-ascent (deflected-gradient) type, which is just the procedure known in the literature when the step-size is taken to be 1. We show that, with probability 1 as the sample size grows large, this procedure converges locally to the strongly consistent maximum-likelihood estimate whenever the step-size lies between 0 and 2. We also show that the step-size which yields optimal local convergence rates for large samples is determined in a sense by the 'separation' of the component normal densities and is bounded below by a number between 1 and 2.

Estimating age ratios and size of pacific walrus herds on coastal haulouts using video imaging.

PubMed

Monson, Daniel H; Udevitz, Mark S; Jay, Chadwick V

2013-01-01

During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance) to classify the sex and age of walruses hauled out on Alaska beaches in 2010-2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m(2) (std. err. = 0.02), herd size ranged from 8,300 to 19,400 (CV 0.03-0.06) and we documented ∼30,000 animals along ∼1 km of beach in 2011. Within the herds, dependent walruses (0-2 yr-olds) tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying) will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species.

Estimating age ratios and size of Pacific walrus herds on coastal haulouts using video imaging

USGS Publications Warehouse

Monson, Daniel H.; Udevitz, Mark S.; Jay, Chadwick V.

2013-01-01

During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance) to classify the sex and age of walruses hauled out on Alaska beaches in 2010–2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m2 (std. err. = 0.02), herd size ranged from 8,300 to 19,400 (CV 0.03–0.06) and we documented ~30,000 animals along ~1 km of beach in 2011. Within the herds, dependent walruses (0–2 yr-olds) tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying) will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species.

Estimating Age Ratios and Size of Pacific Walrus Herds on Coastal Haulouts using Video Imaging

PubMed Central

Monson, Daniel H.; Udevitz, Mark S.; Jay, Chadwick V.

2013-01-01

During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance) to classify the sex and age of walruses hauled out on Alaska beaches in 2010–2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m2 (std. err. = 0.02), herd size ranged from 8,300 to 19,400 (CV 0.03–0.06) and we documented ∼30,000 animals along ∼1 km of beach in 2011. Within the herds, dependent walruses (0–2 yr-olds) tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying) will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species. PMID:23936106

A statistical method for estimating rates of soil development and ages of geologic deposits: A design for soil-chronosequence studies

USGS Publications Warehouse

Switzer, P.; Harden, J.W.; Mark, R.K.

1988-01-01

A statistical method for estimating rates of soil development in a given region based on calibration from a series of dated soils is used to estimate ages of soils in the same region that are not dated directly. The method is designed specifically to account for sampling procedures and uncertainties that are inherent in soil studies. Soil variation and measurement error, uncertainties in calibration dates and their relation to the age of the soil, and the limited number of dated soils are all considered. Maximum likelihood (ML) is employed to estimate a parametric linear calibration curve, relating soil development to time or age on suitably transformed scales. Soil variation on a geomorphic surface of a certain age is characterized by replicate sampling of soils on each surface; such variation is assumed to have a Gaussian distribution. The age of a geomorphic surface is described by older and younger bounds. This technique allows age uncertainty to be characterized by either a Gaussian distribution or by a triangular distribution using minimum, best-estimate, and maximum ages. The calibration curve is taken to be linear after suitable (in certain cases logarithmic) transformations, if required, of the soil parameter and age variables. Soil variability, measurement error, and departures from linearity are described in a combined fashion using Gaussian distributions with variances particular to each sampled geomorphic surface and the number of sample replicates. Uncertainty in age of a geomorphic surface used for calibration is described using three parameters by one of two methods. In the first method, upper and lower ages are specified together with a coverage probability; this specification is converted to a Gaussian distribution with the appropriate mean and variance. In the second method, "absolute" older and younger ages are specified together with a most probable age; this specification is converted to an asymmetric triangular distribution with mode at the

Estimating loss of Brucella abortus antibodies from age-specific serological data in elk

USGS Publications Warehouse

Benavides, J. A.; Caillaud, D.; Scurlock, B. M.; Maichak, E. J.; Edwards, W.H.; Cross, Paul C.

2017-01-01

Serological data are one of the primary sources of information for disease monitoring in wildlife. However, the duration of the seropositive status of exposed individuals is almost always unknown for many free-ranging host species. Directly estimating rates of antibody loss typically requires difficult longitudinal sampling of individuals following seroconversion. Instead, we propose a Bayesian statistical approach linking age and serological data to a mechanistic epidemiological model to infer brucellosis infection, the probability of antibody loss, and recovery rates of elk (Cervus canadensis) in the Greater Yellowstone Ecosystem. We found that seroprevalence declined above the age of ten, with no evidence of disease-induced mortality. The probability of antibody loss was estimated to be 0.70 per year after a five-year period of seropositivity and the basic reproduction number for brucellosis to 2.13. Our results suggest that individuals are unlikely to become re-infected because models with this mechanism were unable to reproduce a significant decline in seroprevalence in older individuals. This study highlights the possible implications of antibody loss, which could bias our estimation of critical epidemiological parameters for wildlife disease management based on serological data.

Age estimation by pulp/tooth ratio in lower premolars by orthopantomography.

PubMed

Cameriere, Roberto; De Luca, Stefano; Alemán, Inmaculada; Ferrante, Luigi; Cingolani, Mariano

2012-01-10

Accurate age estimation has always been a problem for forensic scientists, and apposition of secondary dentine is often used as an indicator of age. Since 2004, in order to examine patterns of secondary dentine apposition, Cameriere et al. have been extensively studying the pulp/tooth area ratio of the canines by panoramic and peri-apical X-ray images. The main aim of this paper is to examine the relationship between age and age-related changes in the pulp/tooth area ratio in monoradicular teeth, with the exception of canines, by orthopantomography. A total of 606 orthopantomograms of Spanish white Caucasian patients (289 women and 317 men), aged between 18 and 75 years and coming from Bilbao and Granada (Spain), was analysed. Regression analysis of age of monoradicular teeth indicated that the lower premolars were the most closely correlated with age. An ANCOVA did not show significant differences between men and women. Multiple regression analysis, with age as dependent variable and pulp/tooth area ratio as predictor, yielded several formulae. R(2) ranged from 0.69 to 0.75 for a single lower premolar tooth and from 0.79 to 0.86 for multiple lower premolar teeth. Depending on the available number of premolar teeth, the mean of the absolute values of residual standard error, at 95% confidence interval, ranged between 4.34 and 6.02 years, showing that the pulp/tooth area ratio is a useful variable for assessing age with reasonable accuracy. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Probability of reduced renal function after contrast-enhanced CT: a model based on serum creatinine level, patient age, and estimated glomerular filtration rate.

PubMed

Herts, Brian R; Schneider, Erika; Obuchowski, Nancy; Poggio, Emilio; Jain, Anil; Baker, Mark E

2009-08-01

The objectives of our study were to develop a model to predict the probability of reduced renal function after outpatient contrast-enhanced CT (CECT)--based on patient age, sex, and race and on serum creatinine level before CT or directly based on estimated glomerular filtration rate (GFR) before CT--and to determine the relationship between patients with changes in creatinine level that characterize contrast-induced nephropathy and patients with reduced GFR after CECT. Of 5,187 outpatients who underwent CECT, 963 (18.6%) had serum creatinine levels obtained within 6 months before and 4 days after CECT. The estimated GFR was calculated before and after CT using the four-variable Modification of Diet in Renal Disease (MDRD) Study equation. Pre-CT serum creatinine level, age, race, sex, and pre-CT estimated GFR were tested using multiple-variable logistic regression models to determine the probability of having an estimated GFR of < 60 and < 45 mL/min/1.73 m(2) after CECT. Two thirds of the patients were used to create and one third to test the models. We also determined discordance between patients who met standard definitions of contrast-induced nephropathy and those with a reduced estimated GFR after CECT. Significant (p < 0.002) predictors for a post-CT estimated GFR of < 60 mL/min/1.73 m(2) were age, race, sex, pre-CT serum creatinine level, and pre-CT estimated GFR. Sex, serum creatinine level, and pre-CT estimated GFR were significant factors (p < 0.001) for predicting a post-CT estimated GFR of < 45 mL/min/1.73 m(2). The probability is [exp(y) / (1 + exp(y))], where y = 6.21 - (0.10 x pre-CT estimated GFR) for an estimated GFR of < 60 mL/min/1.73 m(2), and y = 3.66 - (0.087 x pre-CT estimated GFR) for an estimated GFR of < 45 mL/min/1.73 m(2). A discrepancy between those who met contrast-induced nephropathy criteria by creatinine changes and those with a post-CT estimated GFR of < 60 mL/min/1.73 m(2) was detected in 208 of the 963 patients (21.6%). The

LC-MS/MS-based approach for obtaining exposure estimates of metabolites in early clinical trials using radioactive metabolites as reference standards.

PubMed

Zhang, Donglu; Raghavan, Nirmala; Chando, Theodore; Gambardella, Janice; Fu, Yunlin; Zhang, Duxi; Unger, Steve E; Humphreys, W Griffith

2007-12-01

An LC-MS/MS-based approach that employs authentic radioactive metabolites as reference standards was developed to estimate metabolite exposures in early drug development studies. This method is useful to estimate metabolite levels in studies done with non-radiolabeled compounds where metabolite standards are not available to allow standard LC-MS/MS assay development. A metabolite mixture obtained from an in vivo source treated with a radiolabeled compound was partially purified, quantified, and spiked into human plasma to provide metabolite standard curves. Metabolites were analyzed by LC-MS/MS using the specific mass transitions and an internal standard. The metabolite concentrations determined by this approach were found to be comparable to those determined by valid LC-MS/MS assays. This approach does not requires synthesis of authentic metabolites or the knowledge of exact structures of metabolites, and therefore should provide a useful method to obtain early estimates of circulating metabolites in early clinical or toxicological studies.

Estimating gestational age at birth from fundal height and additional anthropometrics: a prospective cohort study.

PubMed

Pugh, S J; Ortega-Villa, A M; Grobman, W; Newman, R B; Owen, J; Wing, D A; Albert, P S; Grantz, K L

2018-02-23

Accurate assessment of gestational age (GA) is critical to paediatric care, but is limited in developing countries without access to ultrasound. Our objectives were to assess the accuracy of prediction of GA at birth and preterm birth classification using routinely collected anthropometry measures. Prospective cohort study. United States. A total of 2334 non-obese and 468 obese pregnant women. Enrolment GA was determined based on last menstrual period, confirmed by first-trimester ultrasound. Maternal anthropometry and fundal height (FH) were measured by a standardised protocol at study visits; FH alone was additionally abstracted from medical charts. Neonatal anthropometry measurements were obtained at birth. To estimate GA at delivery, we developed three predictor models using longitudinal FH alone and with maternal and neonatal anthropometry. For all predictors, we repeatedly sampled observations to construct training (60%) and test (40%) sets. Linear mixed models incorporated longitudinal maternal anthropometry and a shared parameter model incorporated neonatal anthropometry. We assessed models' accuracy under varied scenarios. Estimated GA at delivery. Prediction error for various combinations of anthropometric measures ranged between 13.9 and 14.9 days. Longitudinal FH alone predicted GA within 14.9 days with relatively stable prediction errors across individual race/ethnicities [whites (13.9 days), blacks (15.1 days), Hispanics (15.5 days) and Asians (13.1 days)], and correctly identified 75% of preterm births. The model was robust to additional scenarios. In low-risk, non-obese women, longitudinal FH measures alone can provide a reasonably accurate assessment of GA when ultrasound measures are not available. Longitudinal fundal height alone predicts gestational age at birth when ultrasound measures are unavailable. © 2018 Royal College of Obstetricians and Gynaecologists.

Age estimation in northern Chinese children by measurement of open apices in tooth roots.

PubMed

Guo, Yu-Cheng; Yan, Chun-Xia; Lin, Xing-Wei; Zhou, Hong; Li, Ju-Ping; Pan, Feng; Zhang, Zhi-Yong; Wei, Lai; Tang, Zheng; Chen, Teng

2015-01-01

The aim of this study was to assess the accuracy of Cameriere's methods on dental age estimation in the northern Chinese population. A sample of orthopantomographs of 785 healthy children (397 girls and 388 boys) aged between 5 and 15 years was collected. The seven left permanent mandibular teeth were evaluated with Cameriere's method. The sample was split into a training set to develop a Chinese-specific prediction formula and a test set to validate this novel developed formula. Following the training dataset study, the variables gender (g), x 3 (canine teeth), x 4 (first premolar), x 7 (second molar), N 0, and the first-order interaction between s and N 0 contributed significantly to the fit, yielding the following linear regression formula: Age = 10.202 + 0.826 g - 4.068x 3 - 1.536x 4 - 1.959x 7 + 0.536 N 0 - 0.219 s [Symbol: see text] N 0, where g is a variable, 1 for boys and 0 for girls. The equation explained 91.2 % (R (2) = 0.912) of the total deviance. By analyzing the test dataset, the accuracy of the European formula and Chinese formula was determined by the difference between the estimated dental age (DA) and chronological age (CA). The European formula verified on the collected Chinese children underestimated chronological age with a mean difference of around -0.23 year, while the Chinese formula underestimated the chronological age with a mean difference of -0.04 year. Significant differences in mean differences in years (DA - CA) and absolute difference (AD) between the Chinese-specific prediction formula and Cameriere's European formula were observed. In conclusion, a Chinese-specific prediction formula based on a large Chinese reference sample could ameliorate the age prediction accuracy in the age group of children.

The effect of age and body composition on body mass estimation of males using the stature/bi-iliac method.

PubMed

Junno, Juho-Antti; Niskanen, Markku; Maijanen, Heli; Holt, Brigitte; Sladek, Vladimir; Niinimäki, Sirpa; Berner, Margit

2018-02-01

The stature/bi-iliac breadth method provides reasonably precise, skeletal frame size (SFS) based body mass (BM) estimations across adults as a whole. In this study, we examine the potential effects of age changes in anthropometric dimensions on the estimation accuracy of SFS-based body mass estimation. We use anthropometric data from the literature and our own skeletal data from two osteological collections to study effects of age on stature, bi-iliac breadth, body mass, and body composition, as they are major components behind body size and body size estimations. We focus on males, as relevant longitudinal data are based on male study samples. As a general rule, lean body mass (LBM) increases through adolescence and early adulthood until people are aged in their 30s or 40s, and starts to decline in the late 40s or early 50s. Fat mass (FM) tends to increase until the mid-50s and declines thereafter, but in more mobile traditional societies it may decline throughout adult life. Because BM is the sum of LBM and FM, it exhibits a curvilinear age-related pattern in all societies. Skeletal frame size is based on stature and bi-iliac breadth, and both of those dimensions are affected by age. Skeletal frame size based body mass estimation tends to increase throughout adult life in both skeletal and anthropometric samples because an age-related increase in bi-iliac breadth more than compensates for an age-related stature decline commencing in the 30s or 40s. Combined with the above-mentioned curvilinear BM change, this results in curvilinear estimation bias. However, for simulations involving low to moderate percent body fat, the stature/bi-iliac method works well in predicting body mass in younger and middle-aged adults. Such conditions are likely to have applied to most human paleontological and archaeological samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

A time-frequency analysis method to obtain stable estimates of magnetotelluric response function based on Hilbert-Huang transform

NASA Astrophysics Data System (ADS)

Cai, Jianhua

2017-05-01

The time-frequency analysis method represents signal as a function of time and frequency, and it is considered a powerful tool for handling arbitrary non-stationary time series by using instantaneous frequency and instantaneous amplitude. It also provides a possible alternative to the analysis of the non-stationary magnetotelluric (MT) signal. Based on the Hilbert-Huang transform (HHT), a time-frequency analysis method is proposed to obtain stable estimates of the magnetotelluric response function. In contrast to conventional methods, the response function estimation is performed in the time-frequency domain using instantaneous spectra rather than in the frequency domain, which allows for imaging the response parameter content as a function of time and frequency. The theory of the method is presented and the mathematical model and calculation procedure, which are used to estimate response function based on HHT time-frequency spectrum, are discussed. To evaluate the results, response function estimates are compared with estimates from a standard MT data processing method based on the Fourier transform. All results show that apparent resistivities and phases, which are calculated from the HHT time-frequency method, are generally more stable and reliable than those determined from the simple Fourier analysis. The proposed method overcomes the drawbacks of the traditional Fourier methods, and the resulting parameter minimises the estimation bias caused by the non-stationary characteristics of the MT data.

The juvenile face as a suitable age indicator in child pornography cases: a pilot study on the reliability of automated and visual estimation approaches.

PubMed

Ratnayake, M; Obertová, Z; Dose, M; Gabriel, P; Bröker, H M; Brauckmann, M; Barkus, A; Rizgeliene, R; Tutkuviene, J; Ritz-Timme, S; Marasciuolo, L; Gibelli, D; Cattaneo, C

2014-09-01

In cases of suspected child pornography, the age of the victim represents a crucial factor for legal prosecution. The conventional methods for age estimation provide unreliable age estimates, particularly if teenage victims are concerned. In this pilot study, the potential of age estimation for screening purposes is explored for juvenile faces. In addition to a visual approach, an automated procedure is introduced, which has the ability to rapidly scan through large numbers of suspicious image data in order to trace juvenile faces. Age estimations were performed by experts, non-experts and the Demonstrator of a developed software on frontal facial images of 50 females aged 10-19 years from Germany, Italy, and Lithuania. To test the accuracy, the mean absolute error (MAE) between the estimates and the real ages was calculated for each examiner and the Demonstrator. The Demonstrator achieved the lowest MAE (1.47 years) for the 50 test images. Decreased image quality had no significant impact on the performance and classification results. The experts delivered slightly less accurate MAE (1.63 years). Throughout the tested age range, both the manual and the automated approach led to reliable age estimates within the limits of natural biological variability. The visual analysis of the face produces reasonably accurate age estimates up to the age of 18 years, which is the legally relevant age threshold for victims in cases of pedo-pornography. This approach can be applied in conjunction with the conventional methods for a preliminary age estimation of juveniles depicted on images.

Obtaining Parts

Science.gov Websites

The Cosmic Connection Parts for the Berkeley Detector Suppliers: Scintillator Eljen Technology 1 obtain the components needed to build the Berkeley Detector. These companies have helped previous the last update. He estimates that the cost to build a detector varies from $1500 to $2700 depending

Sex-specific developmental models for Creophilus maxillosus (L.) (Coleoptera: Staphylinidae): searching for larger accuracy of insect age estimates.

PubMed

Frątczak-Łagiewska, Katarzyna; Matuszewski, Szymon

2018-05-01

Differences in size between males and females, called the sexual size dimorphism, are common in insects. These differences may be followed by differences in the duration of development. Accordingly, it is believed that insect sex may be used to increase the accuracy of insect age estimates in forensic entomology. Here, the sex-specific differences in the development of Creophilus maxillosus were studied at seven constant temperatures. We have also created separate developmental models for males and females of C. maxillosus and tested them in a validation study to answer a question whether sex-specific developmental models improve the accuracy of insect age estimates. Results demonstrate that males of C. maxillosus developed significantly longer than females. The sex-specific and general models for the total immature development had the same optimal temperature range and similar developmental threshold but different thermal constant K, which was the largest in the case of the male-specific model and the smallest in the case of the female-specific model. Despite these differences, validation study revealed just minimal and statistically insignificant differences in the accuracy of age estimates using sex-specific and general thermal summation models. This finding indicates that in spite of statistically significant differences in the duration of immature development between females and males of C. maxillosus, there is no increase in the accuracy of insect age estimates while using the sex-specific thermal summation models compared to the general model. Accordingly, this study does not support the use of sex-specific developmental data for the estimation of insect age in forensic entomology.

Magnetic resonance imaging of third molars: developing a protocol suitable for forensic age estimation.

PubMed

De Tobel, Jannick; Hillewig, Elke; Bogaert, Stephanie; Deblaere, Karel; Verstraete, Koenraad

2017-03-01

Established dental age estimation methods in sub-adults study the development of third molar root apices on radiographs. In living individuals, however, avoiding ionising radiation is expedient. Studying dental development with magnetic resonance imaging complies with this requirement, adding the advantage of imaging in three dimensions. To elaborate the development of an MRI protocol to visualise all third molars for forensic age estimation, with particular attention to the development of the root apex. Ex vivo scans of porcine jaws and in vivo scans of 10 volunteers aged 17-25 years were performed to select adequate sequences. Studied parameters were T1 vs T2 weighting, ultrashort echo time (UTE), fat suppression, in plane resolution, slice thickness, 3D imaging, signal-to-noise ratio, and acquisition time. A bilateral four-channel flexible surface coil was used. Two observers evaluated the suitability of the images. T2-weighted images were preferred to T1-weighted images. To clearly distinguish root apices in (almost) fully developed third molars an in plane resolution of 0.33 × 0.33 mm 2 was deemed necessary. Taking acquisition time limits into account, only a T2 FSE sequence with slice thickness of 2 mm generated images with sufficient resolution and contrast. UTE, thinner slice T2 FSE and T2 3D FSE sequences could not generate the desired resolution within 6.5 minutes. Three Tesla MRI of the third molars is a feasible technique for forensic age estimation, in which a T2 FSE sequence can provide the desired in plane resolution within a clinically acceptable acquisition time.

Estimating Age of Mature Adults from the Degeneration of the Sternal End of the Clavicle

PubMed Central

Falys, Ceri G; Prangle, Dennis

2015-01-01

The sternal end of the clavicle has been illustrated to be useful in aging young adults, however, no studies have investigated what age-related changes occur to the sternal end post epiphyseal fusion. In this study, three morphological features (i.e., surface topography, porosity, and osteophyte formation) were examined and scored using 564 clavicles of individuals of European ancestry (n = 318 males; n = 246 females), with known ages of 40+ years, from four documented skeletal collections: Hamann-Todd, Pretoria, St. Bride's, and Coimbra. An ordinal scoring method was developed for each of the three traits. Surface topography showed the strongest correlation with age, and composite scores (formed by summing the three separate trait scores) indicated progressive degeneration of the surface with increasing chronological age. Linear regression analyses were performed on the trait scores to produce pooled-sample age estimation equations. Blind tests of the composite score method and regression formulae on 56 individuals, aged 40+ years, from Christ Church Spitalfields, suggest accuracies of 96.4% for both methods. These preliminary results display the first evidence of the utility of the sternal end of the clavicle in aging older adult individuals. However, in the current format, these criteria should only be applied to individuals already identified as over 40 years in order to refine the age ranges used for advanced age. These findings do suggest the sternal end of the clavicle has potential to aid age estimates beyond the traditional “mature adult” age category (i.e., 46+ years), and provides several suggestions for future research. Am J Phys Anthropol 156:203–214, 2015. © 2014 The Authors American Journal of Physical Anthropology Published by Wiley Periodicals, Inc. PMID:25327699

Obtaining parsimonious hydraulic conductivity fields using head and transport observations: A Bayesian geostatistical parameter estimation approach

NASA Astrophysics Data System (ADS)

Fienen, M.; Hunt, R.; Krabbenhoft, D.; Clemo, T.

2009-08-01

Flow path delineation is a valuable tool for interpreting the subsurface hydrogeochemical environment. Different types of data, such as groundwater flow and transport, inform different aspects of hydrogeologic parameter values (hydraulic conductivity in this case) which, in turn, determine flow paths. This work combines flow and transport information to estimate a unified set of hydrogeologic parameters using the Bayesian geostatistical inverse approach. Parameter flexibility is allowed by using a highly parameterized approach with the level of complexity informed by the data. Despite the effort to adhere to the ideal of minimal a priori structure imposed on the problem, extreme contrasts in parameters can result in the need to censor correlation across hydrostratigraphic bounding surfaces. These partitions segregate parameters into facies associations. With an iterative approach in which partitions are based on inspection of initial estimates, flow path interpretation is progressively refined through the inclusion of more types of data. Head observations, stable oxygen isotopes (18O/16O ratios), and tritium are all used to progressively refine flow path delineation on an isthmus between two lakes in the Trout Lake watershed, northern Wisconsin, United States. Despite allowing significant parameter freedom by estimating many distributed parameter values, a smooth field is obtained.

Obtaining parsimonious hydraulic conductivity fields using head and transport observations: A Bayesian geostatistical parameter estimation approach

USGS Publications Warehouse

Fienen, M.; Hunt, R.; Krabbenhoft, D.; Clemo, T.

2009-01-01

Flow path delineation is a valuable tool for interpreting the subsurface hydrogeochemical environment. Different types of data, such as groundwater flow and transport, inform different aspects of hydrogeologic parameter values (hydraulic conductivity in this case) which, in turn, determine flow paths. This work combines flow and transport information to estimate a unified set of hydrogeologic parameters using the Bayesian geostatistical inverse approach. Parameter flexibility is allowed by using a highly parameterized approach with the level of complexity informed by the data. Despite the effort to adhere to the ideal of minimal a priori structure imposed on the problem, extreme contrasts in parameters can result in the need to censor correlation across hydrostratigraphic bounding surfaces. These partitions segregate parameters into facies associations. With an iterative approach in which partitions are based on inspection of initial estimates, flow path interpretation is progressively refined through the inclusion of more types of data. Head observations, stable oxygen isotopes (18O/16O ratios), and tritium are all used to progressively refine flow path delineation on an isthmus between two lakes in the Trout Lake watershed, northern Wisconsin, United States. Despite allowing significant parameter freedom by estimating many distributed parameter values, a smooth field is obtained.

A Unified tool to estimate Distances, Ages, and Masses (UniDAM) from spectrophotometric data

NASA Astrophysics Data System (ADS)

Mints, Alexey; Hekker, Saskia

2017-08-01

Context. Galactic archaeology, the study of the formation and evolution of the Milky Way by reconstructing its past from its current constituents, requires precise and accurate knowledge of stellar parameters for as many stars as possible. To achieve this, a number of large spectroscopic surveys have been undertaken and are still ongoing. Aims: So far consortia carrying out the different spectroscopic surveys have used different tools to determine stellar parameters of stars from their derived effective temperatures (Teff), surface gravities (log g), and metallicities ([Fe/H]); the parameters can be combined with photometric, astrometric, interferometric, or asteroseismic information. Here we aim to homogenise the stellar characterisation by applying a unified tool to a large set of publicly available spectrophotometric data. Methods: We used spectroscopic data from a variety of large surveys combined with infrared photometry from 2MASS and AllWISE and compared these in a Bayesian manner with PARSEC isochrones to derive probability density functions (PDFs) for stellar masses, ages, and distances. We treated PDFs of pre-helium-core burning, helium-core burning, and post helium-core burning solutions as well as different peaks in multimodal PDFs (I.e. each unimodal sub-PDF) of the different evolutionary phases separately. Results: For over 2.5 million stars we report mass, age, and distance estimates for each evolutionary phase and unimodal sub-PDF. We report Gaussian, skewed, Gaussian, truncated Gaussian, modified truncated exponential distribution or truncated Student's t-distribution functions to represent each sub-PDF, allowing us to reconstruct detailed PDFs. Comparisons with stellar parameter estimates from the literature show good agreement within uncertainties. Conclusions: We present UniDAM, the unified tool applicable to spectrophotometric data of different surveys, to obtain a homogenised set of stellar parameters. The unified tool and the tables with

A new method for ageing Marbled Murrelets and the effect on productivity estimates

Treesearch

L.L. Long; C.J. Ralph; S. Miller

2001-01-01

Accurate knowledge of the number of newly-fledged juveniles offshore is critical to estimates of productivity of the threatened Marbled Murrelet (Brachyramphus marmoratus). We describe a method for collecting productivity data which allows researchers to objectively evaluate age determinations and their effect on juvenile percentages. This has the...

Postnatal gestational age estimation using newborn screening blood spots: a proposed validation protocol

PubMed Central

Murphy, Malia S Q; Hawken, Steven; Atkinson, Katherine M; Milburn, Jennifer; Pervin, Jesmin; Gravett, Courtney; Stringer, Jeffrey S A; Rahman, Anisur; Lackritz, Eve; Chakraborty, Pranesh; Wilson, Kumanan

2017-01-01

Background Knowledge of gestational age (GA) is critical for guiding neonatal care and quantifying regional burdens of preterm birth. In settings where access to ultrasound dating is limited, postnatal estimates are frequently used despite the issues of accuracy associated with postnatal approaches. Newborn metabolic profiles are known to vary by severity of preterm birth. Recent work by our group and others has highlighted the accuracy of postnatal GA estimation algorithms derived from routinely collected newborn screening profiles. This protocol outlines the validation of a GA model originally developed in a North American cohort among international newborn cohorts. Methods Our primary objective is to use blood spot samples collected from infants born in Zambia and Bangladesh to evaluate our algorithm’s capacity to correctly classify GA within 1, 2, 3 and 4 weeks. Secondary objectives are to 1) determine the algorithm's accuracy in small-for-gestational-age and large-for-gestational-age infants, 2) determine its ability to correctly discriminate GA of newborns across dichotomous thresholds of preterm birth (≤34 weeks, <37 weeks GA) and 3) compare the relative performance of algorithms derived from newborn screening panels including all available analytes and those restricted to analyte subsets. The study population will consist of infants born to mothers already enrolled in one of two preterm birth cohorts in Lusaka, Zambia, and Matlab, Bangladesh. Dried blood spot samples will be collected and sent for analysis in Ontario, Canada, for model validation. Discussion This study will determine the validity of a GA estimation algorithm across ethnically diverse infant populations and assess population specific variations in newborn metabolic profiles. PMID:29104765

An iterative procedure for obtaining maximum-likelihood estimates of the parameters for a mixture of normal distributions, 2

NASA Technical Reports Server (NTRS)