Fieuws, Steffen; Willems, Guy; Larsen-Tangmose, Sara; Lynnerup, Niels; Boldsen, Jesper; Thevissen, Patrick
2016-03-01
When an estimate of age is needed, typically multiple indicators are present as found in skeletal or dental information. There exists a vast literature on approaches to estimate age from such multivariate data. Application of Bayes' rule has been proposed to overcome drawbacks of classical regression models but becomes less trivial as soon as the number of indicators increases. Each of the age indicators can lead to a different point estimate ("the most plausible value for age") and a prediction interval ("the range of possible values"). The major challenge in the combination of multiple indicators is not the calculation of a combined point estimate for age but the construction of an appropriate prediction interval. Ignoring the correlation between the age indicators results in intervals being too small. Boldsen et al. (2002) presented an ad-hoc procedure to construct an approximate confidence interval without the need to model the multivariate correlation structure between the indicators. The aim of the present paper is to bring under attention this pragmatic approach and to evaluate its performance in a practical setting. This is all the more needed since recent publications ignore the need for interval estimation. To illustrate and evaluate the method, Köhler et al. (1995) third molar scores are used to estimate the age in a dataset of 3200 male subjects in the juvenile age range. PMID:26024791
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,…
Jagannathan, N; Neelakantan, P; Thiruvengadam, C; Ramani, P; Premkumar, P; Natesan, A; Herald, J S; Luder, H U
2011-07-01
The present study assessed the suitability of pulp/tooth volume ratio of mandibular canines for age prediction in an Indian population. Volumetric reconstruction of scanned images of mandibular canines from 140 individuals (aged ten - 70 years), using computed tomography was used to measure pulp and tooth volumes. Age calculated using a formula reported earlier for a Belgian sample, resulted in errors > ten years in almost 86% of the study population. The regression equation obtained for the Indian population: Age = 57.18 + (- 413.41 x pulp/tooth volume ratio), was applied to an independent control group (n = 48), and this resulted in mean absolute errors of 8.54 years which was significantly (p < 0.05) lower than those derived with the Belgian formula. The pulp/tooth volume ratio is a useful indicator of age, although correlations may vary in different populations and hence, specific formulae should be applied for the estimates. PMID:21841263
Ethics in age estimation of unaccompanied minors.
Thevissen, P W; Kvaal, S I; Willems, G
2012-11-01
Children absconding from countries of conflict and war are often not able to document their age. When an age is given, it is frequently untraceable or poorly documented and therefore questioned by immigration authorities. Consequently many countries perform age estimations on these children. Provision of ethical practice during the age estimation investigation of unaccompanied minors is considered from different angles: (1) The UN convention on children's rights, formulating specific rights, protection, support, healthcare and education for unaccompanied minors. (2) Since most age estimation investigations are based on medical examination, the four basic principles of biomedical ethics, namely autonomy, beneficence, non-malevolence, justice. (3) The use of medicine for non treatment purposes. (4) How age estimates with highest accuracy in age prediction can be obtained. Ethical practice in age estimation of unaccompanied minors is achieved when different but related aspects are searched, evaluated, weighted in importance and subsequently combined. However this is not always feasible and unanswered questions remain. PMID:23221269
NASA Astrophysics Data System (ADS)
Ningombam, Shantikumar S.; Bagare, S. P.; Khatri, P.; Sohn, B. J.; Song, H.-J.
2015-10-01
Estimation of aerosol radiative forcing (ARF) was performed using a radiative transfer model (Rstar6b) along with physical and optical parameters of aerosols obtained from sky radiometer observation over Indian Astronomical Observatory (IAO), Hanle, Ladakh, during 2008-2010 from dust, anthropogenic, and aged background observing conditions. ARF was estimated at the top of the atmosphere (TOA), in the atmosphere, and at the surface during the three observing conditions. During dust and anthropogenic events, average aerosol optical depth (AOD at 500 nm) went up to 0.24 from the aged background observing condition 0.04. Such enhancement of AOD is associated by the combination of desert-dust and anthropogenic aerosols transported from distant sources as noticed from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). Such three types of aerosols are also identified from the observed properties of single scattering albedo (SSA), aerosol asymmetry (AS) parameter, and aerosol size distribution. The estimated ARFs at TOA, at the surface, and in atmosphere are - 3.73, - 6.82, and 3.40 Wm- 2, respectively during the dust advection period. On the contrary, the respective ARFs during the aged background observing condition are - 1.50, - 2.22, and 0.70 Wm- 2, respectively. A significant difference of spectral AOD is observed during dust, anthropogenic, and aged background observing conditions. Ångström exponent (AE) decreases from 1.05 in the aged background observing condition to 0.40 in the dust event. A significant difference of coarse-fine mode volume distribution is also observed between the dust and the anthropogenic cases. Further, the study reveals high aerosols induced during the dust and the anthropogenic episodes caused warming at atmosphere and cooling at surface which collectively may affect the local atmospheric circulation.
Age estimation from canine volumes.
De Angelis, Danilo; Gaudio, Daniel; Guercini, Nicola; Cipriani, Filippo; Gibelli, Daniele; Caputi, Sergio; Cattaneo, Cristina
2015-08-01
Techniques for estimation of biological age are constantly evolving and are finding daily application in the forensic radiology field in cases concerning the estimation of the chronological age of a corpse in order to reconstruct the biological profile, or of a living subject, for example in cases of immigration of people without identity papers from a civil registry. The deposition of teeth secondary dentine and consequent decrease of pulp chamber in size are well known as aging phenomena, and they have been applied to the forensic context by the development of age estimation procedures, such as Kvaal-Solheim and Cameriere methods. The present study takes into consideration canines pulp chamber volume related to the entire teeth volume, with the aim of proposing new regression formulae for age estimation using 91 cone beam computerized scans and a freeware open-source software, in order to permit affordable reproducibility of volumes calculation. PMID:25698302
ESTIMATION OF AGE TRANSITION PROBABILITIES.
ERIC Educational Resources Information Center
ZINTER, JUDITH R.
THIS NOTE DESCRIBES THE PROCEDURES USED IN DETERMINING DYNAMOD II AGE TRANSITION MATRICES. A SEPARATE MATRIX FOR EACH SEX-RACE GROUP IS DEVELOPED. THESE MATRICES WILL BE USED AS AN AID IN ESTIMATING THE TRANSITION PROBABILITIES IN THE LARGER DYNAMOD II MATRIX RELATING AGE TO OCCUPATIONAL CATEGORIES. THREE STEPS WERE USED IN THE PROCEDURE--(1)…
Forensic Dental Age Estimation: An Overview.
Lewis, James M; Senn, David R
2015-06-01
Forensic age estimation is a scientific process that estimates an individual's true chronologic age by assessing skeletal and dental development and maturation. Although human growth and maturation is unique to each individual, dental techniques for estimating age are currently considered the best in assessing true chronologic age particularly during the age range when the dentition is undergoing morphologic development. This article reviews the principles, methodology and commonly used techniques in forensic age estimation cases. PMID:26126347
Epigenetic estimation of age in humpback whales.
Polanowski, Andrea M; Robbins, Jooke; Chandler, David; Jarman, Simon N
2014-09-01
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 R(2) 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
Age Estimation in Forensic Sciences
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
Age estimation of indian adults from orthopantomographs.
Saxena, Sudhanshu
2011-01-01
The aim of this study was to develop a method for estimating the chronological age of Indian adults based on the relationship between age and various morphological variables of canine teeth, obtained using orthopantomographs. Orthopantomographs of 120 selected patients were digitized, and radiographic images of the right maxillary canine in each case were processed using a computer aided drafting program. Pulp/tooth area ratio, pulp/root length ratio, pulp/tooth length ratio, pulp/root width ratio at the cemento-enamel junction level, pulp/root width ratio at midroot level, and pulp/root width ratio at the midpoint between the cemento-enamel junction and the midroot of the canine were calculated by measuring various features on the images. Pearson's correlation, multiple linear regression, one way analysis of variance (ANOVA), and Student's t-test were used for statistical analysis. Regression equations were developed to estimate age from morphological variables. The observed minus the estimated age in the total study sample ranged from -2.2 to +1.5 years, in males from -0.9 to +0.8 years, while in females it was from -1 to +0.8 years. Differences between observed and estimated ages of subjects were not statistically significant. In conclusion there is a linear relationship of pulp/root width ratio at mid-root level and pulp/tooth area ratio of the right maxillary canine with chronological age in the Indian population. Age of subjects can therefore be estimated with a good degree of accuracy using regression equations. PMID:21503416
Bayesian phylogenetic estimation of fossil ages.
Drummond, Alexei J; Stadler, Tanja
2016-07-19
Recent advances have allowed for both morphological fossil evidence and molecular sequences to be integrated into a single combined inference of divergence dates under the rule of Bayesian probability. In particular, the fossilized birth-death tree prior and the Lewis-Mk model of discrete morphological evolution allow for the estimation of both divergence times and phylogenetic relationships between fossil and extant taxa. We exploit this statistical framework to investigate the internal consistency of these models by producing phylogenetic estimates of the age of each fossil in turn, within two rich and well-characterized datasets of fossil and extant species (penguins and canids). We find that the estimation accuracy of fossil ages is generally high with credible intervals seldom excluding the true age and median relative error in the two datasets of 5.7% and 13.2%, respectively. The median relative standard error (RSD) was 9.2% and 7.2%, respectively, suggesting good precision, although with some outliers. In fact, in the two datasets we analyse, the phylogenetic estimate of fossil age is on average less than 2 Myr from the mid-point age of the geological strata from which it was excavated. The high level of internal consistency found in our analyses suggests that the Bayesian statistical model employed is an adequate fit for both the geological and morphological data, and provides evidence from real data that the framework used can accurately model the evolution of discrete morphological traits coded from fossil and extant taxa. We anticipate that this approach will have diverse applications beyond divergence time dating, including dating fossils that are temporally unconstrained, testing of the 'morphological clock', and for uncovering potential model misspecification and/or data errors when controversial phylogenetic hypotheses are obtained based on combined divergence dating analyses.This article is part of the themed issue 'Dating species divergences using
Bayesian phylogenetic estimation of fossil ages
Drummond, Alexei J.; Stadler, Tanja
2016-01-01
Recent advances have allowed for both morphological fossil evidence and molecular sequences to be integrated into a single combined inference of divergence dates under the rule of Bayesian probability. In particular, the fossilized birth–death tree prior and the Lewis-Mk model of discrete morphological evolution allow for the estimation of both divergence times and phylogenetic relationships between fossil and extant taxa. We exploit this statistical framework to investigate the internal consistency of these models by producing phylogenetic estimates of the age of each fossil in turn, within two rich and well-characterized datasets of fossil and extant species (penguins and canids). We find that the estimation accuracy of fossil ages is generally high with credible intervals seldom excluding the true age and median relative error in the two datasets of 5.7% and 13.2%, respectively. The median relative standard error (RSD) was 9.2% and 7.2%, respectively, suggesting good precision, although with some outliers. In fact, in the two datasets we analyse, the phylogenetic estimate of fossil age is on average less than 2 Myr from the mid-point age of the geological strata from which it was excavated. The high level of internal consistency found in our analyses suggests that the Bayesian statistical model employed is an adequate fit for both the geological and morphological data, and provides evidence from real data that the framework used can accurately model the evolution of discrete morphological traits coded from fossil and extant taxa. We anticipate that this approach will have diverse applications beyond divergence time dating, including dating fossils that are temporally unconstrained, testing of the ‘morphological clock', and for uncovering potential model misspecification and/or data errors when controversial phylogenetic hypotheses are obtained based on combined divergence dating analyses. This article is part of the themed issue ‘Dating species divergences
Targeted estimation of nuisance parameters to obtain valid statistical inference.
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
Improving the quality of parameter estimates obtained from slug tests
Butler, J.J., Jr.; 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.
Bayesian estimation of isotopic age differences
Curl, R.L.
1988-08-01
Isotopic dating is subject to uncertainties arising from counting statistics and experimental errors. These uncertainties are additive when an isotopic age difference is calculated. If large, they can lead to no significant age difference by classical statistics. In many cases, relative ages are known because of stratigraphic order or other clues. Such information can be used to establish a Bayes estimate of age difference which will include prior knowledge of age order. Age measurement errors are assumed to be log-normal and a noninformative but constrained bivariate prior for two true ages in known order is adopted. True-age ratio is distributed as a truncated log-normal variate. Its expected value gives an age-ratio estimate, and its variance provides credible intervals. Bayesian estimates of ages are different and in correct order even if measured ages are identical or reversed in order. For example, age measurements on two samples might both yield 100 ka with coefficients of variation of 0.2. Bayesian estimates are 22.7 ka for age difference with a 75% credible interval of (4.4, 43.7) ka.
Reliability of fish size estimates obtained from multibeam imaging sonar
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
Calibration age and quartet divergence date estimation.
Brochu, Christopher A
2004-06-01
The date of a single divergence point--between living alligators and crocodiles--was estimated with quartet dating using calibrations of widely divergent ages. For five mitochondrial sequence datasets, there is a clear relationship between calibration age and quartet estimate--quartets based on two relatively recent calibrations support younger divergence estimates than do quartets based on two older calibrations. Some of the estimates supported by young quartets are impossibly young and exclude the first appearance of the group in the fossil record as too old. The older estimates--those based on two relatively old calibrations--may be overestimates, and those based on one old and one recent calibration support divergence estimates very close to fossil data. This suggests that quartet dating methods may be most effective when calibrations are applied from different parts of a clade's history. PMID:15266985
Relative Attribute SVM+ Learning for Age Estimation.
Wang, Shengzheng; Tao, Dacheng; Yang, Jie
2016-03-01
When estimating age, human experts can provide privileged information that encodes the facial attributes of aging, such as smoothness, face shape, face acne, wrinkles, and bags under-eyes. In automatic age estimation, privileged information is unavailable to test images. To overcome this problem, we hypothesize that asymmetric information can be explored and exploited to improve the generalizability of the trained model. Using the learning using privileged information (LUPI) framework, we tested this hypothesis by carefully defining relative attributes for support vector machine (SVM+) to improve the performance of age estimation. We term this specific setting as relative attribute SVM+ (raSVM+), in which the privileged information enables separation of outliers from inliers at the training stage and effectively manipulates slack variables and age determination errors during model training, and thus guides the trained predictor toward a generalizable solution. Experimentally, the superiority of raSVM+ was confirmed by comparing it with state-of-the-art algorithms on the face and gesture recognition research network (FG-NET) and craniofacial longitudinal morphological face aging databases. raSVM+ is a promising development that improves age estimation, with the mean absolute error reaching 4.07 on FG-NET. PMID:25850101
Age estimation using intraoral periapical radiographs
Rajpal, Pooja S.; Krishnamurthy, Vasavi; Pagare, Sandeep S.; Sachdev, Geeta D.
2016-01-01
Context: Changes in the size of dental pulp caused by the apposition of secondary dentin and occlusal wear are morphometric parameters for estimating age. Aim: To estimate the accuracy of age evaluation by Kvaal's method and the effect of occlusal wear on age using digital intraoral periapical radiographs in a subset of the Indian population. Materials and Methods: A total of 300 teeth were radiographically evaluated using intraoral periapical digital radiographs from 50 adult patients. A few modifications were made in the design of the study compared to the original Kvaal's method. The radiographs of three teeth from each jaw were taken and morphometric measurements in ratios were analyzed, which included the pulp length to tooth length (X1), pulp length to root length (X2), pulp width to root widths at three defined levels (X3), and tooth length to root length (X4). Statistical Analysis: The Pearson product-moment correlation coefficient (PCC) between age and the morphological variables showed that among them X1, X2, and X3 were statistically significant but not the tooth root length ratio (X4). Conclusions: The ratios X1, X2, and X3 were good indicators of age and hence a multiple linear regression model for age estimation was derived using these three variables. However, it was found that X4 was not a good indicator of age estimation in said population. PMID:27051226
Bayesian calibration for forensic age estimation.
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. PMID:25645903
NASA Astrophysics Data System (ADS)
Salih, A. L.; Mühlbauer, M.; Grumpe, A.; Pasckert, J. H.; Wöhler, C.; Hiesinger, H.
2016-06-01
The analysis of the impact crater size-frequency distribution (CSFD) is a well-established approach to the determination of the age of planetary surfaces. Classically, estimation of the CSFD is achieved by manual crater counting and size determination in spacecraft images, which, however, becomes very time-consuming for large surface areas and/or high image resolution. With increasing availability of high-resolution (nearly) global image mosaics of planetary surfaces, a variety of automated methods for the detection of craters based on image data and/or topographic data have been developed. In this contribution a template-based crater detection algorithm is used which analyses image data acquired under known illumination conditions. Its results are used to establish the CSFD for the examined area, which is then used to estimate the absolute model age of the surface. The detection threshold of the automatic crater detection algorithm is calibrated based on a region with available manually determined CSFD such that the age inferred from the manual crater counts corresponds to the age inferred from the automatic crater detection results. With this detection threshold, the automatic crater detection algorithm can be applied to a much larger surface region around the calibration area. The proposed age estimation method is demonstrated for a Kaguya Terrain Camera image mosaic of 7.4 m per pixel resolution of the floor region of the lunar crater Tsiolkovsky, which consists of dark and flat mare basalt and has an area of nearly 10,000 km2. The region used for calibration, for which manual crater counts are available, has an area of 100 km2. In order to obtain a spatially resolved age map, CSFDs and surface ages are computed for overlapping quadratic regions of about 4.4 x 4.4 km2 size offset by a step width of 74 m. Our constructed surface age map of the floor of Tsiolkovsky shows age values of typically 3.2-3.3 Ga, while for small regions lower (down to 2.9 Ga) and higher
Estimating age in black South African children.
Uys, A; Fabris-Rotelli, I; Bernitz, H
2014-03-01
Forensic dentists are frequently required to determine the age at death of unidentified skeletons, or to age live individuals who have no record/documentation of their chronological age. In order to be of the greatest value, the method used should have the lowest possible standard deviation and be validated for the individual's specific population group. The method most frequently used in Forensic Dentistry for the estimation of age in children, was described by Demirjian et al. The maturity standards determined were based on samples of French Canadian origin and it has been recommended by several authors that correction factors be incorporated when applying this method to different population groups. The current research was carried out on a sample of 838 black South African children. A new model for age estimation in the said population was developed, to accurately determine the chronological age from dental development. A sample of 604 black South African children was used to test the validity of the method described by Demirjian. PMID:24974518
Age estimation and validation for South Pacific albacore Thunnus alalunga.
Farley, J H; Williams, A J; Clear, N P; Davies, C R; Nicol, S J
2013-05-01
Validated estimates of age are presented for albacore Thunnus alalunga, sampled from a large part of the south-western Pacific Ocean, based on counts of annual opaque growth zones from transverse sections of otoliths. Counts of daily increments were used to estimate the location of the first opaque growth zone, which was completed before the first assumed birthday. The periodicity of opaque zones was estimated by marginal increment analysis and an oxytetracycline mark-recapture experiment. Both validation methods indicated that opaque zones formed over the austral summer and were completed by autumn to winter (April to August). The direct comparison of age estimates obtained from otoliths and dorsal-fin spines of the same fish indicated bias, which was assumed to be due to poor increment clarity and resorption of early growth zones in spines, resulting in imprecise age estimates. As such, age estimates from otoliths are considered to be more accurate than those from spines for T. alalunga. This is consistent with results for a growing number of tropical and temperate tuna Thunnini species. It is recommend that validated counts of annual growth zones from sectioned otoliths is used as the preferred method for estimating age-based parameters for assessment and management advice for these important stocks. PMID:23639152
Merging Satellites, Models and Gauges to Obtain New Precipitation Estimates
NASA Astrophysics Data System (ADS)
Sapiano, M.; Smith, T.; Arkin, P. A.; Janowiak, J.
2009-12-01
The most frequently used merged satellite/gauge global analyses of precipitation are the Global Precipitation Climatology Project (GPCP) analysis and the CPC Merged Analysis of Precipitation (CMAP). The multi-source nature of these datasets allows them to use the best data available to produce the most accurate estimate of precipitation for any given place and time. However, the quality of these datasets is reduced over mid- and high-latitude oceans where satellite estimates are of lower quality. Additionally, discontinuities, artifacts and inhomogeneities can be introduced by the use of time-varying inputs, which can impact the suitability of these datasets for investigation of long-term changes in global precipitation. The Multi-Source Analysis of Precipitation (MSAP) is a new global analysis of precipitation using Optimum Interpolation (OI) which naturally yields errors associated with the analysis that are needed for many applications. The initial version of the dataset uses the relatively long, consistent precipitation record (~20 years) from the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave/Imager (SSM/I) and forecast precipitation from the ERA-40 reanalysis. This version has been updated to include the ERA-Interim data which extends the record to 22 years, as well as several other modifications and corrections. We will also show results form recent experiments to construct an even longer version of MSAP which uses satellite estimate based on the OLR record which extends to 30 years.
Uncertainty Estimates of Psychoacoustic Thresholds Obtained from Group Tests
NASA Technical Reports Server (NTRS)
Rathsam, Jonathan; Christian, Andrew
2016-01-01
Adaptive psychoacoustic test methods, in which the next signal level depends on the response to the previous signal, are the most efficient for determining psychoacoustic thresholds of individual subjects. In many tests conducted in the NASA psychoacoustic labs, the goal is to determine thresholds representative of the general population. To do this economically, non-adaptive testing methods are used in which three or four subjects are tested at the same time with predetermined signal levels. This approach requires us to identify techniques for assessing the uncertainty in resulting group-average psychoacoustic thresholds. In this presentation we examine the Delta Method of frequentist statistics, the Generalized Linear Model (GLM), the Nonparametric Bootstrap, a frequentist method, and Markov Chain Monte Carlo Posterior Estimation and a Bayesian approach. Each technique is exercised on a manufactured, theoretical dataset and then on datasets from two psychoacoustics facilities at NASA. The Delta Method is the simplest to implement and accurate for the cases studied. The GLM is found to be the least robust, and the Bootstrap takes the longest to calculate. The Bayesian Posterior Estimate is the most versatile technique examined because it allows the inclusion of prior information.
Probabilities and statistics for backscatter estimates obtained by a scatterometer
NASA Technical Reports Server (NTRS)
Pierson, Willard J., Jr.
1989-01-01
Methods for the recovery of winds near the surface of the ocean from measurements of the normalized radar backscattering cross section must recognize and make use of the statistics (i.e., the sampling variability) of the backscatter measurements. Radar backscatter values from a scatterometer are random variables with expected values given by a model. A model relates backscatter to properties of the waves on the ocean, which are in turn generated by the winds in the atmospheric marine boundary layer. The effective wind speed and direction at a known height for a neutrally stratified atmosphere are the values to be recovered from the model. The probability density function for the backscatter values is a normal probability distribution with the notable feature that the variance is a known function of the expected value. The sources of signal variability, the effects of this variability on the wind speed estimation, and criteria for the acceptance or rejection of models are discussed. A modified maximum likelihood method for estimating wind vectors is described. Ways to make corrections for the kinds of errors found for the Seasat SASS model function are described, and applications to a new scatterometer are given.
Age estimation of adults from dental radiographs.
Kvaal, S I; Kolltveit, K M; Thomsen, I O; Solheim, T
1995-07-28
Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearson's correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r2) for the estimation was strongest when the ratios
NASA Astrophysics Data System (ADS)
Tracy, R. J.; Loehn, C. W.; Dahl, P. S.; Aleinikoff, J. N.; Wooden, J. L.; Hamilton, M.; Mazdab, F.; Jones, C.
2005-12-01
In situ analytical techniques for geochronology are rapidly becoming the method of choice for characterizing compositionally and chronologically complex minerals, including monazite (mnz) and zircon (zrc). Two such techniques include Ion Microprobe (IMP) (esp. SHRIMP) for both mnz and zrc, and electron microprobe (EMP) for mnz. Debate remains concerning comparability of ages obtained by the two different techniques: U-Pb isotopic dating (IMP) versus Th-total U-total Pb (EMP). The IMP has an advantage in analytical precision whereas the EMP has an advantage in spatial resolution. We report 6 examples of individual monazite grains that have been dated by both techniques, covering a range of ages from 300 to 2850 Ma. Three of our examples are grains that have been used as IMP standards at the Geological Survey of Canada (GSC) or at the USGS-Stanford SHRIMP lab; the other grains are from research samples. Most grains display complex zoning in Y, Th and U, both in BSE images and in compositional maps, reflecting complex growth and recrystallization histories. In all cases, the ages obtained by the two techniques agree within their 2-sigma associated error, except where IMP ablation pits cross age boundaries and resolve a mixed age of the two domains, or where EMP spots fall near cracks or pits in the grain surface. One prominent example is a 100-micron mnz from the Tobacco Root Mountains, Montana. It contains a low-Th older core (ca. 2.85 Ga), a higher-Th mantle domain of about 2.45 Ga, and a low-Th rim of 1.78 Ga. This grain has 6 IMP spots that range in age from 1880 Ma (near-rim) to 2785 Ma (core). Only two IMP pits fall totally within a single chemical and age zone delineated by EMP analyses or compositional maps (the medial age zone): 2451 (+/-4) and 2432 (+/-10). The weighted mean EMP age of this domain is 2452 (+/-6). IMP spots aimed at the older core are 2619 (+/-11) and 2785 (+/-9); the weighted mean core age from EMP analyses is 2859 (+/-14). This suggests
Using Dental Age to Estimate Chronological Age in Czech Children Aged 3-18 Years.
Ginzelová, Kristina; Dostálová, Taťjana; Eliášová, Hana; Vinšů, Alex; Buček, Antonín; Bučková, Michaela
2015-01-01
The Demirjian methods to determine dental age are based on analysis of orthopantograms. The dental age estimation is based on establishing the tooth development stages. The purpose of this study was to assess the accuracy of estimation of dental age by Demirjian in the use of all of his four methods. 505 Czech healthy boys and girls aged 3 to 18 years were examined radiographically at the Department of Stomatology, Second Faculty of Medicine, Charles University in Prague. It was mentioned the factors of underlying diseases influence the accuracy of the dental age estimation. For statistical evaluation, descriptive statistics was used to compare deviations of the mean values of chronological and dental age in each age group. The resulting difference between dental age and chronological age is not significant in both genders only when using both Demirjian 7-teeth methods of 1973 and 1976. Therefore these may be most appropriately used for forensic age estimation. There are shown standard deviation differences in different countries. Demirjian's original 7-teeth method from 1973 and Demirjian's revised 4-teeth method from 1976 appear to be the best methods for calculating the dental age of healthy Czech children of both genders. PMID:26093668
Utilization of bone impedance for age estimation in postmortem cases.
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. PMID:26421720
Technology Transfer Automated Retrieval System (TEKTRAN)
Accurate estimation of the water balance estimation is essential to many hydrological, agricultural, and meteorological applications, which use observation- or model-based water balance elements. Observations obtained from local meteorological and hydrological stations are very accurate; however, th...
Age estimation from physiological changes of teeth: A reliable age marker?
Singh, Nishant; Grover, Neeraj; Puri, Navin; Singh, Sanjeet; Arora, Swati
2014-01-01
Background: Age is an essential factor in establishing the identity of a person. Teeth are one of the most durable and resilient part of skeleton. Gustafson (1950) suggested the use of six retrogressive dental changes that are seen with increasing age. Aim: The aim of the study was to evaluate the results and to check the reliability of modified Gustafson's method for determining the age of an individual. Materials and Methods: Total 70 patients in the age group of 20-65 years, undergoing extraction were included in this present work. The ground sections of extracted teeth were prepared and examined under the microscope. Modified Gustafson's criteria were used for the estimation of age. Degree of attrition, root translucency, secondary dentin deposition, cementum apposition, and root resorption were measured. A linear regression formula was obtained using different statistical equations in a sample of 70 patients. Results: The mean age difference of total 70 cases studied was ±2.64 years. Difference of actual and calculated age was significant and was observed at 5% level of significance, that is, t-cal > t-tab (t-cal = 7.72). P < 0.05, indicates that the results were statistically significant. Conclusion: The present study concludes that Gustafson's method is a reliable method for age estimation with some proposed modifications. PMID:25125919
A comparison of methods used to obtain age ratios of snow and Canada geese
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.
Estimating the Age Distribution of Oceanic Dissolved Organic Carbon
NASA Astrophysics Data System (ADS)
Follett, C. L.; Forney, D. C.; Repeta, D.; Rothman, D.
2010-12-01
Dissolved organic carbon (DOC) is a large, ubiquitous component of open ocean water at all depths and impacts atmospheric carbon dioxide levels at both short and long timescales. It is currently believed that oceanic DOC contains a multi-thousand-year-old refractory deep-water component which is mixed with a young labile component in surface waters. Unfortunately, the only evidence for this comes from a few isolated depth profiles of both DOC concentration and bulk radiocarbon. Although the profile data is consistent with a two-component mixing model, directly separating the two components has proven to be a challenge. We explore the validity of the two component mixing model by directly estimating the age distribution of oceanic DOC. The two-component model suggests that the age distribution is composed of two distinct peaks. In order to obtain an estimate of the age distribution we first record changes in both concentration and percent radiocarbon as a sample is oxidized under ultra-violet radiation [1]. We formulate a mathematical model relating the age distribution to these changes, assuming that they result from components of different radiocarbon age and UV-reactivity. This allows us to numerically invert the data and estimate the age distribution. We apply our procedure to DOC samples collected from three distinct depths (50, 500, and 2000 meters) in the north-central Pacific Ocean. [1] S.R. Beaupre, E.R.M. Druffel, and S. Griffin. A low-blank photochemical extraction system for concentration and isotopic analyses of marine dissolved organic carbon. Limnol. Oceanogr. Methods, 5:174-184, 2007.
Estimating Neuronal Ageing with Hidden Markov Models
NASA Astrophysics Data System (ADS)
Wang, Bing; Pham, Tuan D.
2011-06-01
Neuronal degeneration is widely observed in normal ageing, meanwhile the neurode-generative disease like Alzheimer's disease effects neuronal degeneration in a faster way which is considered as faster ageing. Early intervention of such disease could benefit subjects with potentials of positive clinical outcome, therefore, early detection of disease related brain structural alteration is required. In this paper, we propose a computational approach for modelling the MRI-based structure alteration with ageing using hidden Markov model. The proposed hidden Markov model based brain structural model encodes intracortical tissue/fluid distribution using discrete wavelet transformation and vector quantization. Further, it captures gray matter volume loss, which is capable of reflecting subtle intracortical changes with ageing. Experiments were carried out on healthy subjects to validate its accuracy and robustness. Results have shown its ability of predicting the brain age with prediction error of 1.98 years without training data, which shows better result than other age predition methods.
Impairment of age estimation from faces in Alzheimer's disease.
Moyse, Evelyne; Bastin, Christine; Salmon, Eric; Brédart, Serge
2015-01-01
A prerequisite for any function in social cognition is the perception and processing of social cues. Age estimation is a skill that is used in everyday life and is fundamental in social interactions. This study evaluated whether facial age estimation is impaired in patients with mild to moderate Alzheimer's disease (AD). The current age of faces is known to have an impact on age estimation, and therefore stimuli belonging to different age groups (young, middle-aged, and older adults' faces) were used. As expected, an impairment of age estimation from faces was observed in mild to moderate AD patients. However, the profile of impairment depended on the age of faces and stage of the disease. Mild AD patients presented difficulties mainly in assessing the age of middle-aged adults. In moderate disease stage, these difficulties also affected the age estimation of young adult faces. Interestingly, AD patients remained relatively good at estimating the age of older adults' faces, compared to healthy controls. PMID:25589725
Estimating the age of alleles by use of intraallelic variability
Slatkin, M.; Rannala, B.
1997-02-01
A method is presented for estimating the age of an allele by use of its frequency and the extent of variation among different copies. The method uses the joint distribution of the number of copies in a population sample and the coalescence times of the intraallelic gene genealogy conditioned on the number of copies. The linear birth-death process is used to approximate the dynamics of a rare allele in a finite population. A maximum-likelihood estimate of the age of the allele is obtained by Monte Carlo integration over the coalescence times. The method is applied to two alleles at the cystic fibrosis (CFTR) locus, {Delta}F508 and G542X, for which intraallelic variability at three intronic microsatellite loci has been examined. Our results indicate that G542X is somewhat older than {Delta}F508. Although absolute estimates depend on the mutation rates at the microsatellite loci, our results support the hypothesis that {Delta}F508 arose <500 generations ({approx}10,000 years) ago. 32 refs., 4 figs.
Age at death estimation from bone histology in Malaysian males.
Nor, Faridah Mohd; Pastor, Robert F; Schutkowski, Holger
2014-10-01
Estimation of age from microscopic examination of human bone utilizes bone remodeling. This allows 2 regression equation to be determined in a specific population based on the variation in osteon turnover in different populations. The aim of this study was to provide age estimation for Malaysian males. Ground undecalcified cross sections were prepared from long limb bones of 50 deceased males aged between 21 and 78 years. Ten microstructural parameters were measured and subjected to multivariate regression analysis. Results showed that osteon count had the highest correlation with age (R = 0.43), and age was estimated to be within 10.94 years of the true value in 98% of males. Cross validation of the equation on 50 individuals showed close correspondence of true ages with estimated ages. Further studies are needed to validate and expand these results. PMID:24189643
Stability and control derivative estimates obtained from flight data for the Beech 99 aircraft
NASA Technical Reports Server (NTRS)
Tanner, R. R.; Montgomery, T. D.
1979-01-01
Lateral-directional and longitudinal stability and control derivatives were determined from flight data by using a maximum likelihood estimator for the Beech 99 airplane. Data were obtained with the aircraft in the cruise configuration and with one-third flap deflection. The estimated derivatives show good agreement with the predictions of the manufacturer.
Age estimation based on Kvaal's technique using digital panoramic radiographs
Mittal, Samta; Nagendrareddy, Suma Gundareddy; Sharma, Manisha Lakhanpal; Agnihotri, Poornapragna; Chaudhary, Sunil; Dhillon, Manu
2016-01-01
Introduction: Age estimation is important for administrative and ethical reasons and also because of legal consequences. Dental pulp undergoes regression in size with increasing age due to secondary dentin deposition and can be used as a parameter of age estimation even beyond 25 years of age. Kvaal et al. developed a method for chronological age estimation based on the pulp size using periapical dental radiographs. There is a need for testing this method of age estimation in the Indian population using simple tools like digital imaging on living individuals not requiring extraction of teeth. Aims and Objectives: Estimation of the chronological age of subjects by Kvaal's method using digital panoramic radiographs and also testing the validity of regression equations as given by Kvaal et al. Materials and Methods: The study sample included a total of 152 subjects in the age group of 14-60 years. Measurements were performed on the standardized digital panoramic radiographs based on Kvaal's method. Different regression formulae were derived and the age was assessed. The assessed age was then correlated to the actual age of the patient using Student's t-test. Results: No significant difference between the mean of the chronological age and the estimated age was observed. However, the values of the mean age estimated by using regression equations as given previously in the study of Kvaal et al. significantly underestimated the chronological age in the present study sample. Conclusion: The results of the study give an inference for the feasibility of this technique by calculation of regression equations on digital panoramic radiographs. However, it negates the applicability of same regression equations as given by Kvaal et al. on the study population.
Dental Age Estimation Helps Create a New Identity.
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. PMID:26079404
The effects of racemization rate for age estimation of pink teeth.
Sakuma, Ayaka; Saitoh, Hisako; Ishii, Namiko; Iwase, Hirotaro
2015-03-01
Pink teeth is thought to result from the seepage of hemoglobin caused by dental pulp decomposition. We investigated whether racemization can be applied for age estimation in cases of pink teeth where the whole tooth is used. The pink teeth used were three cases and the normal teeth for control were five mandibular canines of known age. Age of the pink teeth was calculated on the basis of regression formula obtained from the five control teeth. Only a slight error was noted between the actual and estimated ages of the pink teeth (R(2) = 0.980, r = 0.990): Cases 1-3 actually aged 23, 53, and 59 years were estimated to be 26, 52, and 60 years. Based on our results of testing pink teeth of known age, we suggest that racemization techniques allow for the age estimation of pink teeth using the same methods for normally colored teeth. PMID:25684096
Baverel, Paul G; Savic, Radojka M; Karlsson, Mats O
2011-02-01
When parameter estimates are used in predictions or decisions, it is important to consider the magnitude of imprecision associated with the estimation. Such imprecision estimates are, however, presently lacking for nonparametric algorithms intended for nonlinear mixed effects models. The objective of this study was to develop resampling-based methods for estimating imprecision in nonparametric distribution (NPD) estimates obtained in NONMEM. A one-compartment PK model was used to simulate datasets for which the random effect of clearance conformed to a (i) normal (ii) bimodal and (iii) heavy-tailed underlying distributional shapes. Re-estimation was conducted assuming normality under FOCE, and NPDs were estimated sequential to this step. Imprecision in the NPD was then estimated by means of two different resampling procedures. The first (full) method relies on bootstrap sampling from the raw data and a re-estimation of both the preceding parametric (FOCE) and the nonparametric step. The second (simplified) method relies on bootstrap sampling of individual nonparametric probability distributions. Nonparametric 95% confidence intervals (95% CIs) were obtained and mean errors (MEs) of the 95% CI width were computed. Standard errors (SEs) of nonparametric population estimates were obtained using the simplified method and evaluated through 100 stochastic simulations followed by estimations (SSEs). Both methods were successfully implemented to provide imprecision estimates for NPDs. The imprecision estimates adequately reflected the reference imprecision in all distributional cases and regardless of the numbers of individuals in the original data. Relative MEs of the 95% CI width of CL marginal density when original data contained 200 individuals were equal to: (i) -22 and -12%, (ii) -22 and -9%, (iii) -13 and -5% for the full and simplified (n = 100), respectively. SEs derived from the simplified method were consistent with the ones obtained from 100 SSEs. In conclusion
Calibrating recruitment estimates for mourning doves from harvest age ratios
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
Precision of two methods for estimating age from burbot otoliths
Edwards, W.H.; Stapanian, M.A.; Stoneman, A.T.
2011-01-01
Lower reproductive success and older age structure are associated with many burbot (Lota lota L.) populations that are declining or of conservation concern. Therefore, reliable methods for estimating the age of burbot are critical for effective assessment and management. In Lake Erie, burbot populations have declined in recent years due to the combined effects of an aging population (&xmacr; = 10 years in 2007) and extremely low recruitment since 2002. We examined otoliths from burbot (N = 91) collected in Lake Erie in 2007 and compared the estimates of burbot age by two agers, each using two established methods (cracked-and-burned and thin-section) of estimating ages from burbot otoliths. One ager was experienced at estimating age from otoliths, the other was a novice. Agreement (precision) between the two agers was higher for the thin-section method, particularly at ages 6–11 years, based on linear regression analyses and 95% confidence intervals. As expected, precision between the two methods was higher for the more experienced ager. Both agers reported that the thin sections offered clearer views of the annuli, particularly near the margins on otoliths from burbot ages ≥8. Slides for the thin sections required some costly equipment and more than 2 days to prepare. In contrast, preparing the cracked-and-burned samples was comparatively inexpensive and quick. We suggest use of the thin-section method for estimating the age structure of older burbot populations.
NASA Astrophysics Data System (ADS)
Botto, A.; Ganora, D.; Laio, F.; Claps, P.
2012-04-01
Traditionally, flood frequency analysis has been used to assess the design discharge for hydraulic infrastructures. Unfortunately, this method involves uncertainties, be they of random or epistemic nature. Despite some success in measuring uncertainty, e.g. by means of numerical simulations, exhaustive methods for their evaluation are still an open challenge to the scientific community. The proposed method aims to improve the standard models for design flood estimation, considering the hydrological uncertainties inherent with the classic flood frequency analysis, in combination with cost-benefit analysis. Within this framework, two of the main issues related to flood risk are taken into account: on the one hand statistical flood frequency analysis is complemented with suitable uncertainty estimates; on the other hand the economic value of the flood-prone land is considered, as well as the economic losses in case of overflow. Consider a case where discharge data are available at the design site: the proposed procedure involves the following steps: (i) for a given return period T the design discharge is obtained using standard statistical inference (for example, using the GEV distribution and the method of L- moments to estimate the parameters); (ii) Monte Carlo simulations are performed to quantify the parametric uncertainty related to the design-flood estimator: 10000 triplets of L-moment values are randomly sampled from their relevant multivariate distribution, and 10000 values of the T-year discharge are obtained ; (iii) a procedure called the least total expected cost (LTEC) design approach is applied as described hereafter: linear cost and damage functions are proposed so that the ratio between the slope of the damage function and the slope of the cost function is equal to T. The expected total cost (sum of the cost plus the expected damage) is obtained for each of the 10000 design value estimators, and the estimator corresponding to the minimum total cost is
NASA Astrophysics Data System (ADS)
Rios, Edmilson Helton; Figueiredo, Irineu; Moss, Adam Keith; Pritchard, Timothy Neil; Glassborow, Brent Anthony; Domingues, Ana Beatriz Guedes; Azeredo, Rodrigo Bagueira de Vasconcellos
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.
NASA Astrophysics Data System (ADS)
Rios, Edmilson Helton; Figueiredo, Irineu; Moss, Adam Keith; Pritchard, Timothy Neil; Glassborow, Brent Anthony; Domingues, Ana Beatriz Guedes; Azeredo, Rodrigo Bagueira de Vasconcellos
2016-04-01
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 cutoff. Select portions of the longitudinal (T1) and transverse (T2) relaxation-time distributions are systematically evaluated by applying various cutoffs, 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.
Discriminating Projections for Estimating Face Age in Wild Images
Tokola, Ryan A; Bolme, David S; Ricanek, Karl; Barstow, Del R; Boehnen, Chris Bensing
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-class 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.
Age-dependent forest carbon sink: Estimation via inverse modeling
NASA Astrophysics Data System (ADS)
Zhou, Tao; Shi, Peijun; Jia, Gensuo; Dai, Yongjiu; Zhao, Xiang; Shangguan, Wei; Du, Ling; Wu, Hao; Luo, Yiqi
2015-12-01
Forests have been recognized to sequester a substantial amount of carbon (C) from the atmosphere. However, considerable uncertainty remains regarding the magnitude and time course of the C sink. Revealing the intrinsic relationship between forest age and C sink is crucial for reducing uncertainties in prediction of forest C sink potential. In this study, we developed a stepwise data assimilation approach to combine a process-based Terrestrial ECOsystem Regional model, observations from multiple sources, and stochastic sampling to inversely estimate carbon cycle parameters including carbon sink at different forest ages for evergreen needle-leaved forests in China. The new approach is effective to estimate age-dependent parameter of maximal light-use efficiency (R2 = 0.99) and, accordingly, can quantify a relationship between forest age and the vegetation and soil C sinks. The estimated ecosystem C sink increases rapidly with age, peaks at 0.451 kg C m-2 yr-1 at age 22 years (ranging from 0.421 to 0.465 kg C m-2 yr-1), and gradually decreases thereafter. The dynamic patterns of C sinks in vegetation and soil are significantly different. C sink in vegetation first increases rapidly with age and then decreases. C sink in soil, however, increases continuously with age; it acts as a C source when the age is less than 20 years, after which it acts as a sink. For the evergreen needle-leaved forest, the highest C sink efficiency (i.e., C sink per unit net primary productivity) is approximately 60%, with age between 11 and 43 years. Overall, the inverse estimation of carbon cycle parameters can make reasonable estimates of age-dependent C sequestration in forests.
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.
Ages estimated from a diffusion equation model for scarp degradation
Colman, Steven M.; Watson, K.E.N.
1983-01-01
The diffusion equation derived from the continuity equation for hillslopes is applied to scarp erosion in unconsolidated materials. Solutions to this equation allow direct calculation of the product of the rate coefficient and the age of the scarp from measurements of scarp morphology. Where the rate coefficient can be estimated or can be derived from scarps of known age, this method allows direct calculation of unknown ages of scarps.
Influence of sectioning location on age estimates from common carp dorsal spines
Watkins, Carson J.; Klein, Zachary B.; Terrazas, Marc M.; Quist, Michael
2015-01-01
Dorsal spines have been shown to provide precise age estimates for Common CarpCyprinus carpio and are commonly used by management agencies to gain information on Common Carp populations. However, no previous studies have evaluated variation in the precision of age estimates obtained from different sectioning locations along Common Carp dorsal spines. We evaluated the precision, relative readability, and distribution of age estimates obtained from various sectioning locations along Common Carp dorsal spines. Dorsal spines from 192 Common Carp were sectioned at the base (section 1), immediately distal to the basal section (section 2), and at 25% (section 3), 50% (section 4), and 75% (section 5) of the total length of the dorsal spine. The exact agreement and within-1-year agreement among readers was highest and the coefficient of variation lowest for section 2. In general, age estimates derived from sections 2 and 3 had similar age distributions and displayed the highest concordance in age estimates with section 1. Our results indicate that sections taken at ≤ 25% of the total length of the dorsal spine can be easily interpreted and provide precise estimates of Common Carp age. The greater consistency in age estimates obtained from section 2 indicates that by using a standard sectioning location, fisheries scientists can expect age-based estimates of population metrics to be more comparable and thus more useful for understanding Common Carp population dynamics.
Age synthesis and estimation via faces: a survey.
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. PMID:20847387
Estimation of gestational age from gall-bladder length.
Udaykumar, K; Udaykumar, Padmaja; Nagesh, K R
2016-01-01
Establishing a precise duration of gestation is vital in situations such as infanticide and criminal abortions. The present study attempted to estimate the gestational age of the foetus from gall-bladder length. Foetuses of various gestational age groups were dissected, and the length of the gall bladder was measured. The results were analysed, and a substantial degree of correlation was statistically confirmed. This novel method is helpful when the foetus is fragmented, putrefied or eviscerated, where this method can be used as an additional parameter to improve the accuracy of foetal age estimation. PMID:25990829
Characterization of rhenium compounds obtained by electrochemical synthesis after aging process
Vargas-Uscategui, Alejandro; Mosquera, Edgar; López-Encarnación, Juan M.; Chornik, Boris; Katiyar, Ram S.; Cifuentes, Luis
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 theory (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.
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.
Comparison of two phase scintillation estimators for GPS data obtained from High Latitudes.
NASA Astrophysics Data System (ADS)
Mushini, S. C.; Thayyil, J. P.; Langley, R. B.; MacDougall, J. W.
2009-05-01
Radio waves propagating through small scale plasma density irregularities produce fluctuations in both amplitude and phase of the signal. These fluctuations are called ionospheric scintillations. Due to their spatial diversity, GPS satellites allow scintillation measurement from different azimuthal sectors. Reliability of derived scintillation indices depend on the scintillation estimators used. Here we compare two different estimators for phase scintillations for data obtained from Canadian High Arctic Ionospheric Network (CHAIN) GPS receivers at high latitudes. These stations are specifically chosen to represent polar cap, near to the auroral boundary, and sub-auroral regions . Results of the comparison and its implications will be discussed.
Conventional versus digital approach for measuring dentin translucency in forensic age estimation
Chopra, Varun; Thodasam, Gopal; Ahmad, Zeeshan Heera; Singh, Simranjit; Rajawat, Indresh; Gupta, Sonal
2015-01-01
Background: Root dentine translucency remains the method of choice providing the most accurate results for age estimation. Conventionally, translucency is measured using calipers. In recent times, computer-based methods are proposed, which require the use of custom-built software programs. Aims and Objectives: The aim was to use a digital method to measure dentinal translucency on sectioned teeth and to compare digital measurements to conventionally obtained translucency measurements. Materials and Methods: A total of 200 extracted permanent teeth were collected and were sectioned to a thickness of 250 μm. Translucency measurements were obtained using the digital method and compared with those obtained using a caliper. Results: Correlation coefficients of translucency measurements to age were statistically significant for both methods (P < 0.001), although marginally higher correlation was observed for the conventional method (r = 0.612). Application of derived linear regression equations on an independent sample (n = 25) suggested that conventional approach is marginally better in estimating age to within 5 years of the actual age, both the methods are similar in assessing age within 5-10 years of the actual age, and digital approach is marginally better in estimating age beyond 10 years of actual age. Conclusion: The translucency measurements obtained by the two methods were identical, with no clear superiority of one method over the other. PMID:25810651
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. PMID:23010906
Pulse arrival time estimation from the impedance plethysmogram obtained with a handheld device.
Gomez-Clapers, J; Casanella, R; Pallas-Areny, R
2011-01-01
This paper describes a novel method to estimate pulse arrival time (PAT) from the electrocardiogram (ECG) and the impedance plethysmogram (TPG) obtained by using a compact and easy-to-use handheld device with only four electrodes. A proof-of-concept has been carried out where PAT values obtained with the proposed device have been compared to PAT values measured between the ECG and the photoplethysmogram (PPG) during three experiments of paced respiration to induce controlled PAT changes. The results show that both methods yield equivalent PAT values in within ± 7 ms (95 % confidence interval), which is less than typical deviations reported for common PAT measurements. PMID:22254361
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.
Age estimation for forensic purposes in Italy: ethical issues.
Focardi, Martina; Pinchi, Vilma; De Luca, Federica; Norelli, Gian-Aristide
2014-05-01
Age assessment in children and young adults is a relevant medicolegal issue due to the gradual increase of persons devoid of proper identification documents in European countries. Because of the illegal immigration and growing crime rates among children and adolescents, age estimation for forensic purposes is often required. The scientific research and the extensive experience of forensic experts in the last decades focused on the use of radiographic methods addressed to evaluate the degree of skeletal or dental development as the most accurate parameters to estimate the chronological age of children and adolescents. This paper analyzes the ethical issues related to age estimation procedures based on radiographic methods, showing how the ethical principles of beneficence, nonmalevolence, justice, and autonomy may be guaranteed during the execution of the age assessment in forensic practice. The procedure might be conducted in accordance with international guidelines and protocols, though they need a higher homogenization and standardization. A strong collaboration between various scientific societies of professionals (forensic odontologists, forensic pathologists, forensic anthropologist, radiologists, pediatricians, and psychologists), who have been involved in age estimation for years, is needed to reach this goal. PMID:24633466
A test of the Lamendin method of age estimation in South African canines.
Ackermann, Anja; Steyn, Maryna
2014-03-01
Age estimation in unknown adult skeletons remains a considerable problem in forensic anthropology. In 1992, Lamendin et al. published a non-destructive method of age estimation on single rooted teeth. With this method, periodontosis and root transparency are judged against root height, and these are then used in regression formulae to estimate age. The aim of this study was to test the accuracy of the Lamendin method on a large sample of canines of South Africans, and if necessary to adapt the formulae for this population. A sample of known sex, age and population group was used. This included 537 upper and lower canines from 498 skulls, and included black males, black females, white males and white females. The age of the individuals ranged from 20 to 90 years. The original formulae gave relatively poor results, and in an attempt to obtain better accuracy the formulae were adapted with the current data. Even after adaptation of the formulae, the highest correlation between estimated age and actual age remained low (R(2)=0.41), with mean errors ranging between 12 and 15 years. Periodontosis was better correlated with age than root transparency. The accuracy of the method was found to be much lower than what was originally published, but probably reflects biological reality and is on a par with other methods of adult age estimation. PMID:24445081
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.
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.
Markers of Oxidative Stress in Senescent Erythrocytes Obtained from Young and Old Age Rats
Kumar, Dileep
2014-01-01
Abstract The role of oxidative stress during aging is well documented. Evidence is available linking animal life span to the development of oxidative stress. Up to a certain limit of oxidative stress, cells function to counteract the oxidant effects and to restore redox balance by resetting critical homeostatic parameters. Red blood cells (RBCs) offer a very good model to study cellular senescence. In vivo aging of red blood cells is associated with increased cellular density, which corresponds to increased cell age. The present study aims to investigate age-dependent oxidative stress in RBC subpopulations obtained after Percoll density gradient centrifugation from young and old rats. We observe an increase in plasma membrane redox system (PMRS) activity (p<0.001) and lipid peroxidation (p<0.001) between less dense and senescent RBCs in both young and old rats. Our findings provide evidence of a higher level of oxidative stress in senescent erythrocytes, with the effect being more pronounced in old (24-month-old) rats compared to young (4-month-old) rats. The present findings emphasize the role of oxidative stress not only in organismal aging but also in cell senescence. PMID:25065263
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.
Mello, Beatriz; Schrago, Carlos G
2014-01-01
Divergence time estimation has become an essential tool for understanding macroevolutionary events. Molecular dating aims to obtain reliable inferences, which, within a statistical framework, means jointly increasing the accuracy and precision of estimates. Bayesian dating methods exhibit the propriety of a linear relationship between uncertainty and estimated divergence dates. This relationship occurs even if the number of sites approaches infinity and places a limit on the maximum precision of node ages. However, how the placement of calibration information may affect the precision of divergence time estimates remains an open question. In this study, relying on simulated and empirical data, we investigated how the location of calibration within a phylogeny affects the accuracy and precision of time estimates. We found that calibration priors set at median and deep phylogenetic nodes were associated with higher precision values compared to analyses involving calibration at the shallowest node. The results were independent of the tree symmetry. An empirical mammalian dataset produced results that were consistent with those generated by the simulated sequences. Assigning time information to the deeper nodes of a tree is crucial to guarantee the accuracy and precision of divergence times. This finding highlights the importance of the appropriate choice of outgroups in molecular dating. PMID:24855333
Dental age estimation standards for a Western Australian population.
Karkhanis, Shalmira; Mack, Peter; Franklin, Daniel
2015-12-01
Age estimation in the juvenile skeleton primarily relies on the assessment of the degree of dental and skeletal development relative to full maturity. The timing of the mineralization and eruption of the teeth is a sequential process that, compared to skeletal growth and development, is less affected by extrinsic influences such as nutrition and/or chronic illness. Accordingly, radiographic visualization and analysis of different tooth formation stages are the foundation for a number of widely applied age estimation standards. Presently, however, there is a relative paucity of contemporary dental age estimation standards for a Western Australian population. To that end, the aim of the present study is to develop statistically quantified radiographic age estimation standards for a Western Australian juvenile population. A total of 392 digital orthopantomograms (202 male and 190 female) of Western Australian individuals are analyzed. Following, Moorrees et al. (J. Dent. Res. 42 (1963a) 490-502; Am. J. Phys. Anthropol. 21 (1963) 205-213), dental development and root resorption was assessed. Alveolar eruption was analyzed following Bengston (Northwest Univ. Bull. 35 (1935) 3-9). Stages of dental development were used to formulate a series of age estimation polynomial regression models; prediction accuracy (±0.998 to 2.183 years) is further validated using a cross-validation (holdout) sample of 30 film orthopantomograms. A visual atlas of dental development and eruption was subsequently designed for the pooled sex sample. The standards presented here represent a non-invasive and statistically quantified approach for accurate dental age estimation in Western Australian juvenile individuals. PMID:26344558
Statistical estimation of mineral age by K-Ar method
Vistelius, A.B.; Drubetzkoy, E.R.; Faas, A.V. )
1989-11-01
Statistical estimation of age of {sup 40}Ar/{sup 40}K ratios may be considered a result of convolution of uniform and normal distributions with different weights for different minerals. Data from Gul'shad Massif (Nearbalkhash, Kazakhstan, USSR) indicate that {sup 40}Ar/{sup 40}K ratios reflecting the intensity of geochemical processes can be resolved using convolutions. Loss of {sup 40}Ar in biotites is shown whereas hornblende retained the original content of {sup 40}Ar throughout the geological history of the massif. Results demonstrate that different estimation methods must be used for different minerals and different rocks when radiometric ages are employed for dating.
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.
Objective measurement of shade color in age estimation
Vaidya, Sharad; Ahuja, Nitin; Bajaj, Puneet; Kapoor, Charu; Sabarwal, Robin; Rajpal, Karan
2015-01-01
Introduction: Age estimation is an important subspecialty of forensic medicine. Dental hard tissues are highly resistant to degradation and putrefaction. Enamel is translucent and varies in color from light yellow to grey white. The color of the teeth has been reported to be affected by chronological age. Enamel color may also depend on environmental factors viz. diet, occupational habits, vitamin deficiencies, fluoride level in drinking water etc., It has been found that color changes in dentin vary from white to yellow. Studies have been done to measure the dentin color for age estimation. Aim: To find a correlation between the enamel color and chronological age and secondly to estimate the age of an individual from enamel color. Material and Methods: A total of 300 patients visiting the outpatient department of oral medicine and radiology were selected. Out of those, 150 were men and 150 women. The patients were divided into V groups based on the age. A thorough case history was taken for all the patients. Maxillary Central and Lateral incisor was used for the estimation of shade. The enamel color was evaluated using a VITA classical shade guide. Statistical Analysis: Data were exported to an Excel spread sheet and statistical analysis was performed using the SPSS. Linear regression analysis was used to find correlations between age and enamel shade. Results: In the group 1 and 2 i.e. from 15 to 36 years, the shades A 2 and B 2 (reddish hue) was found to be most common. While in the group 3 and 4, shades ranged from A 3 to B 3 (brownish to yellowish hue). In the patients above 59 years i.e. group 5 the enamel shade with greyish hue was found to be most common. Conclusion: Age determination using enamel color can be tried in forensic cases in the identification of individuals with no birth records. PMID:26816455
Karkhanis, Shalmira; Mack, Peter; Franklin, Daniel
2014-02-01
In the present global socio-political scenario, an increasing demand exists for age estimation in living persons, such as refugees and asylum seekers, who seldom have any documentation for proof of identity. Age estimation in the living poses significant challenges because the methods need to be non-invasive, accurate and ethically viable. Methods based on the analysis of the pulp chamber are recommended for age estimation in living adults. There is, however, a paucity of studies of this nature and population specific standards in Western Australia. The aim of the present study is therefore, to test the reliability and applicability of the method developed by Kvaal et al. (1995) for the purpose of developing age estimation standards for an adult Western Australian population. A total of 279 digital orthopantomograms (143 female; and 136 male) of Australian individuals were analysed. A subset of the total sample (50) was removed as a cross-validation (holdout) sample. Following the method described in Kvaal et al. (1995), length and width measurements of the tooth and pulp chamber were acquired in maxillary central and lateral incisors; second premolars, mandibular lateral incisors; canines and first premolars. Those measurements were then used to calculate a series of ratios (length and width), which were subsequently used to formulate age estimation regression models. The most accurate model based on a single tooth was for the maxillary central incisor (SEE ±9.367 years), followed by the maxillary second premolar (SEE ±9.525 years). Regression models based on the measurement of multiple teeth improved age prediction accuracy (SEE ±7.963 years). The regression models presented here have expected accuracy rates comparable (if not higher than) to established skeletal morphoscopic methods. This method, therefore, offers a statistically quantified methodological approach for forensic age estimation in Western Australian adults. PMID:24411636
NASA Astrophysics Data System (ADS)
Hochuli, Roman; Beard, Paul C.; Cox, Ben
2015-03-01
In photoacoustic tomography (PAT) the image contrast is due to optical absorption, and because of this PAT images are sensitive to changes in blood oxygen saturation (sO2). However, this is not a linear relationship due to the presence of a non-uniform light fluence distribution. In this paper we systematically evaluate the conditions in which an approximate linear inversion scheme-which assumes the internal fluence distribution is unchanged when the absorption coefficient changes-can give accurate estimates of sO2. A numerical phantom of highly vascularised tissue is used to test this assumption. It is shown that using multiple wavelengths over a broad range of the near-infrared spectrum yields inaccurate estimates of oxygenation, while a careful selection of wavelengths in the 620-920nm range is likely to yield more accurate oxygenation values. We demonstrate that a 1D fluence correction obtained by fitting a linear function to the average decay rate in the image can further improve the estimates. However, opting to use these longer wavelengths involves sacrificing signal-to-noise ratio in the image, as the absorption of blood is low in this range. This results in an inherent trade-off between error in the sO2 estimates due to fluence variation and error due to noise. This study shows that the depth to which sO2 can be estimated accurately using a linear approximation is limited in vivo, even with idealised measurements, to at most 3mm. In practice, there will be even greater uncertainties affecting the estimates, e.g., due to bandlimited or partial-view acoustic detection.
Dental age estimation of growing children by measurement of open apices: A Malaysian formula
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
How old am I? Age estimation in living adults: a case report.
Cattaneo, C; De Angelis, D; Ruspa, M; Gibelli, D; Cameriere, R; Grandi, M
2008-12-01
Age estimation is a common task in forensic medicine. Odontologists are frequently involved in the age assessment of human remains or living juveniles. The need to estimate the age of living individuals is becoming more frequent, because of the increasing number of immigrants (illegal or otherwise) without acceptable identification documents and with missing or uncertain birth dates. Whereas age estimation in subadults is usually performed by methods based on the physiological growth of bones and teeth, in the case of living adults age determination is more difficult, because body maturation has come to an end and the most commonly used procedures in forensics on human remains are too invasive for the living individual. The following case report aims at highlighting the difficulties of performing age estimation in the living adult and the importance of a multidisciplinary approach including forensic odontology: a middle-aged woman from Ethiopia who was supposed to be 62 years old (according to one set of documents), was removed from employment lists as she had reached the retirement age for Italy. However another set of documents indicated a younger age (46 years). Hormonal dosage of E2 (17-β estradiol) and FSH (Follicle Stimulating Hormone) showed an age close to the begininng of menopause. An experimental dental method, based on the decrease of canine pulp chamber with age, was performed in order to obtain more information: the result was an estimation of a 47-57 age range. Combined results suggested that it was more likely that the actual age of the woman was closer to 46 than to 62. PMID:22717788
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.
Age estimation from the acetabulum in South African black males.
Botha, D; Pretorius, S; Myburgh, J; Steyn, M
2016-05-01
Anthropologists are constantly seeking to improve methods for age estimation in the human skeleton. A new method was introduced about a decade ago that assesses the morphological changes that take place in the acetabulum as an individual ages. The pelvis is usually well preserved in forensic cases, which makes this method potentially valuable as an adult age indicator. This method employs seven variables, each with its own set of phases. To test the accuracy and reliability of this method, 100 black South African male acetabula from the Pretoria Bone Collection were assessed based on the criteria described in the original study. Box plots and transition curves were constructed to establish whether progression with age was visible and how it could possibly be modelled. Inter-observer reliability was also assessed by making use of Fleiss's Kappa statistic. Five specimens were used as out-of-sample examples for which maximum likelihood (point) estimates were calculated. The results demonstrated that middle and older individuals' age estimates were vastly underestimated. Inter-observer repeatability was poor, which suggested that the classification system most likely needs to be modified. A discussion and recommendation is given for improvement of reliability and repeatability of this method. PMID:26662190
Mayhew, T M; Pharaoh, A; Austin, A; Fagan, D G
1997-07-01
Design-based stereology is employed to estimate total numbers of myocyte nuclei and mean myocyte volume per nucleus in ventricles of fetal and early postnatal human hearts. Organs were collected postmortem from subjects varying in age from 16 gestational wk to 40 postnatal wk. Numbers of myocyte nuclei per unit volume of ventricle were estimated using physical disectors (parallel pairs of sections). Absolute numbers were calculated by multiplying nuclear packing densities by ventricular volumes estimated from ventricular mass and tissue density. Volumes per nucleus were obtained via estimates of the combined volumes of all myocytes (or of the myocardium as a whole) and the numbers of myocyte nuclei. The findings showed that numbers of myocyte nuclei increase linearly from 16 wk towards term. They were also consistent with the notion that hyperplasia ceases abruptly at birth or soon afterwards. The net rate of production of myocyte nuclei was about 38 x 10(7)/wk (2.3 million nuclei/h). The total volume of myocytes continued to expand in the same way from 16 wk to at least 35 wk of gestation. Published studies on the incidence of binucleate myocytes during early postnatal growth of the ventricles of rats suggest that the volume of a myocyte doubles prior to nuclear division. Prenatal growth in the human heart is consistent with this mechanism. Myocardial hypertrophy after birth must occur by cellular hypertrophy without karyokinesis. PMID:9279664
Challenges in Obtaining Estimates of the Risk of Tuberculosis Infection During Overseas Deployment.
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. PMID:26416114
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 hydrogeologie 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 faci??s 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. Copyright 2009 by the American Geophysical Union.
Human Age Estimation Method Robust to Camera Sensor and/or Face Movement.
Nguyen, Dat Tien; Cho, So Ra; Pham, Tuyen Danh; Park, Kang Ryoung
2015-01-01
Human age can be employed in many useful real-life applications, such as customer service systems, automatic vending machines, entertainment, etc. In order to obtain age information, image-based age estimation systems have been developed using information from the human face. However, limitations exist for current age estimation systems because of the various factors of camera motion and optical blurring, facial expressions, gender, etc. Motion blurring can usually be presented on face images by the movement of the camera sensor and/or the movement of the face during image acquisition. Therefore, the facial feature in captured images can be transformed according to the amount of motion, which causes performance degradation of age estimation systems. In this paper, the problem caused by motion blurring is addressed and its solution is proposed in order to make age estimation systems robust to the effects of motion blurring. Experiment results show that our method is more efficient for enhancing age estimation performance compared with systems that do not employ our method. PMID:26334282
Human Age Estimation Method Robust to Camera Sensor and/or Face Movement
Nguyen, Dat Tien; Cho, So Ra; Pham, Tuyen Danh; Park, Kang Ryoung
2015-01-01
Human age can be employed in many useful real-life applications, such as customer service systems, automatic vending machines, entertainment, etc. In order to obtain age information, image-based age estimation systems have been developed using information from the human face. However, limitations exist for current age estimation systems because of the various factors of camera motion and optical blurring, facial expressions, gender, etc. Motion blurring can usually be presented on face images by the movement of the camera sensor and/or the movement of the face during image acquisition. Therefore, the facial feature in captured images can be transformed according to the amount of motion, which causes performance degradation of age estimation systems. In this paper, the problem caused by motion blurring is addressed and its solution is proposed in order to make age estimation systems robust to the effects of motion blurring. Experiment results show that our method is more efficient for enhancing age estimation performance compared with systems that do not employ our method. PMID:26334282
Fetal age estimation using MSCT scans of deciduous tooth germs.
Minier, Marie; Maret, Delphine; Dedouit, Fabrice; Vergnault, Marion; Mokrane, Fathima-Zohra; Rousseau, Hervé; Adalian, Pascal; Telmon, Norbert; Rougé, Daniel
2014-01-01
Evaluation of fetal age is an essential element in many fields such as anthropology, odontology, paleopathology, and forensic sciences. This study examines the correlation between fetal age, femoral diaphyseal length (considered as the gold standard), and deciduous tooth germs of fetuses aged 22 to 40 weeks amenorrhea (WA) based on computed tomography (MSCT) reconstructions. Qualitative and quantitative studies of femoral and deciduous tooth germ lengths were performed on 81 fetuses (39 females and 42 males). R software was used for statistical analyses. Intra-observer and inter-observer variabilities and the interclass correlation coefficient (ICC) were calculated. Correlation coefficients (R (2)) and linear regression equations were calculated. Intra- and inter-observer variabilities were very satisfactory (intra-observer ICC ≥ 0.96, inter-observer ICC ≥ 0.95). Femoral length was significantly correlated with age (R (2) = 0.9). The correlation coefficient between age and height, width, and dental volume was R (2) ≥ 0.73. Tooth germs were good indicators of fetal age. Our method appears to be reliable and reproducible, and the results of this study agreed with those of the literature. The dental formula provided a precise estimation of fetal age between 25 and 32 WA. Tooth germs were reliable indicators of fetal age, and multislice computed tomography was shown to be an innovative and reliable technology for this purpose. PMID:23828625
Relationship Between Mitochondrial DNA Mutations and Aging. Estimation of Age-at-death.
Zapico, Sara C; Ubelaker, Douglas H
2016-04-01
Some studies have pointed to the relationship between mitochondrial DNA (mtDNA) mutations and age in different tissues, which are potentially interesting in aging research and in forensic identification because they could help to improve the estimation of age-at-death. The present study aims to evaluate the mutations in mtDNA from dentin and pulp and their relation with age. Healthy erupted third molars were extracted from individuals from two Spanish populations, aged 20-70. When analyzing the amplification of hypervariable region 2 of the mtDNA by real-time polymerase chain reaction, a negative strong linear correlation was found between the mtDNA amplification and age in dentin from both populations. In contrast, a significant correlation between mtDNA amplification and age in pulp was not discovered, probably due to the majority of the mitochondria are placed in dentin. A difference in mtDNA damage between these two populations was also detected, indicating the role of ancestry as a component. The findings from this research enrich the current studies related to aging and mitochondrial damage and provide a new quantitative tool for estimating the age-at-death that, in combination with traditional age markers, could improve identification accuracy in forensic cases. PMID:26286606
Estimating carbon stocks based on forest volume-age relationship
NASA Astrophysics Data System (ADS)
Hangnan, Y.; Lee, W.; Son, Y.; Kwak, D.; Nam, K.; Moonil, K.; Taesung, K.
2012-12-01
This research attempted to estimate potential change of forest carbon stocks between 2010 and 2110 in South Korea, using the forest cover map and National Forest Inventory (NFI) data. Allometric functions (logistic regression models) of volume-age relationships were developed to estimate carbon stock change during upcoming 100 years for Pinus densiflora, Pinus koraiensis, Pinus rigida, Larix kaempferi,and Quercus spp. The current forest volume was estimated with the developed regression model and 4th forest cover map. The future volume was predicted by developed volume-age models with adding n years to current age. As a result, we found that the total forest volume would increase from 126.89 m^3/ha to 246.61 m^3/ha and the carbon stocks would increase from 90.55 Mg C ha^(-1) to 174.62 Mg C ha^(-1) during 100 years when current forest remains unchanged. The carbon stocks would increase by approximately 0.84 Mg C ha^(-1) yr^(-1), which has high value if considering other northern countries' (Canada, Russia, China) -0.10 ~ 0.28 Mg C ha^(-1) yr^(-1) in pervious study. This can be attributed to the fact that mixed forest and bamboo forest in this study did not considered. Moreover, it must be influenced by that the change of carbon stocks was estimated without the consideration of mortality, thinning, and tree species' change in this study. ;
A non-destructive dental method for age estimation.
Kvaal, S; Solheim, T
1994-06-01
Dental radiographs have rarely been used in dental age estimation methods for adults and the aim of this investigation was to derive formulae for age calculation based on measurements of teeth and their radiographs. Age-related changes were studied in 452 extracted, unsectioned incisors, canines and premolars. The length of the apical translucent zone and extent of the periodontal retraction were measured on the teeth while the pulp length and width as well as root length and width were measured on the radiographs and the ratios between the root and pulp measurements calculated. For all types of teeth significant, negative Pearson's correlation coefficients were found between age and the ratios between the pulp and the root width. In this study also, the correlation between age and the length of the apical translucent zone was weaker than expected. The periodontal retraction was significantly correlated with age in maxillary premolars alone. Multiple regression analyses showed inclusion of the ratio between the measurements of the pulp and the root on the radiographs for all teeth; the length of the apical translucency in five types; and periodontal retraction in only three types of teeth. The correlation coefficients ranged from r = 0.48 to r = 0.90 between the chronological and the calculated age using the formulae from this multiple regression study. The strongest coefficients were for premolars. These formulae may be recommended for use in odontological age estimations in forensic and archaeological cases where teeth are loose or can be extracted and where it is important that the teeth are not sectioned. PMID:9227083
Revisiting the analog method to obtain uncertainty estimates for proxy surrogate reconstructions
NASA Astrophysics Data System (ADS)
Bothe, Oliver
2015-04-01
Proxy surrogate reconstructions are a computationally cheap method to combine information from spatially sparse proxy records or instrumental data series with the spatially complete fields from climate simulations to increase our knowledge about past climates. The method assumes that the analog pool includes the entire bandwidth of the state-space of the variable under consideration. As proxy records are uncertain indicators of the state of past climate variables, the analog search should ideally allow for the inclusion of the variance unexplained by the proxy indicator in the variable of interest, i.e. it should quantify the uncertainty of the reconstructions based on the signal strength in the proxy records. Upto this point traditional implementations have not considered this uncertainty. This presentation details assumptions based on the calibration correlation of the proxies which result in an ensemble pool of analogs consistent with the proxy record at each data point and explicitly considering the noise in the proxy record. The proxy-pool of the Euro2K-reconstruction and the MPI-ESM-COSMOS ensemble of simulations of the last millennium provide the data to obtain a set of proxy surrogate field estimates for the June, July and August summer near surface air temperature of the last 750 years for the European domain. The restrictions imposed on the analog selection can result in failure to find suitable analogs. The underlying assumptions allow to construct an uncertainty envelope for the areal mean of the field reconstructions. The ensemble of fields further highlights the ambiguity of field reconstructions constrained by a limited set of proxies. Additionally, the uncertainty envelope, its median estimate and the respective best estimate can be used to easily validate reconstructions obtained with more complex methods. That is, the proxy surrogate reconstruction estimates agree very well with the Euro2K-reconstruction over the last 750 years. They also well
Age estimation by pulp/tooth ratio in canines by peri-apical X-rays.
Cameriere, Roberto; Ferrante, Luigi; Belcastro, Maria Giovanna; Bonfiglioli, Benedetta; Rastelli, Elisa; Cingolani, Mariano
2007-01-01
Estimation of age in individuals has received considerable attention in forensic science, in which it is a widely used method for individual identification, together with paleo-demographic analyses to establish mortality patterns in past populations. The present investigation, which is a continuation of a previously published pilot study, was conducted to examine the possible application of the pulp/tooth area ratio by peri-apical images as an indicator of age at death. A total of 200 peri-apical X-rays of upper and lower canines were assembled from 57 male and 43 female skeletons of Caucasian origin, aged between 20 and 79 years. They belong to the Frassetto osteological collection of Sassari (Sardinia) and are housed in the Museum of Anthropology, Department of Experimental and Evolutionistic Biology, University of Bologna. For each skeleton, dental maturity was evaluated by measuring the pulp/tooth area ratio on upper (x(1)) and lower (x(2)) canines. Very good agreement was found between intraobserver measurements. Statistical analysis was performed in order to obtain multiple regression formulae for dental age calculation, with chronological age as dependent variable, and gender, and upper and lower canines as independent variables. Stepwise regression analysis showed that gender did not contribute significantly to the fit (p=0.881) whereas variables x(1) and x(2) and the first-order interaction between them did. These two variables explained 92.5% of variations in estimated chronological age and the residual standard error was 4.06 years. Lastly, two simple linear regression equations were obtained for age estimation using canines from the maxilla and mandible separately. Both models explained 86% of variations in estimated chronological age and allowed an age-at-death estimate with a residual standard error of about 5.4 years. PMID:17209930
Age estimation of bloodstains using smartphones and digital image analysis.
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. PMID:24314532
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.
Human Age Estimation Based on Locality and Ordinal Information.
Li, Changsheng; Liu, Qingshan; Dong, Weishan; Zhu, Xiaobin; Liu, Jing; Lu, Hanqing
2015-11-01
In this paper, we propose a novel feature selection-based method for facial age estimation. The face aging is a typical temporal process, and facial images should have certain ordinal patterns in the aging feature space. From the geometrical perspective, a facial image can be usually seen as sampled from a low-dimensional manifold embedded in the original high-dimensional feature space. Thus, we first measure the energy of each feature in preserving the underlying local structure information and the ordinal information of the facial images, respectively, and then we intend to learn a low-dimensional aging representation that can maximally preserve both kinds of information. To further improve the performance, we try to eliminate the redundant local information and ordinal information as much as possible by minimizing nonlinear correlation and rank correlation among features. Finally, we formulate all these issues into a unified optimization problem, which is similar to linear discriminant analysis in format. Since it is expensive to collect the labeled facial aging images in practice, we extend the proposed supervised method to a semi-supervised learning mode including the semi-supervised feature selection method and the semi-supervised age prediction algorithm. Extensive experiments are conducted on the FACES dataset, the Images of Groups dataset, and the FG-NET aging dataset to show the power of the proposed algorithms, compared to the state-of-the-arts. PMID:26470062
Application OF LIBS To Estimate The Age Of Broiler Breeders
NASA Astrophysics Data System (ADS)
Salam, Z. Abdel; Harith, M. A.
2011-09-01
Laser Induced Breakdown Spectroscopy (LIBS) is a well-known spectrochemical elemental analysis technique. In our investigations of the LIBS spectra it has been found that there is a remarkable correlation between the ionic to atomic spectral lines emission ratio and the surface hardness of eggshell for two Different Broiler Breeder at different age. The proposed technique has been applied successfully in poultry science to estimate the age of broiler breeders by measuring the surface hardness of their eggshell. The experiments have been performed on two different strains, Arbor Acres plus (AAP) and Hubard Classic (HC), and the results were satisfactory.
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.
The Prevalence of Age-Related Eye Diseases and Visual Impairment in Aging: Current Estimates
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
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.
Age Estimation in Living Egyptians Using Signal Joint T-cell Receptor Excision Circle Rearrangement.
Ibrahim, Samah F; Gaballah, Iman F; Rashed, Laila A
2016-07-01
Age estimation is one of the challenges in forensic sciences. There are many techniques to estimate the age. Molecular biology approach is one of these techniques. Signal joint T-cell receptor excision circles gene (sjTRECs), is one of this approach. We aimed to use sjTRECs as a suitable marker for age estimation among Egyptian population. TaqMan qPCR approach was used to quantify sjTREC levels in blood samples obtained from 153 healthy Egyptian individuals ranging from a few weeks to 70 years. Our results showed a significant negative correlation between sjTREC levels and age with p ≤ 0.05. Moreover, the individual's age can be determined through this formula Age = -30.671+ (-5.998Y) (Y is dCtTBP - sjTREC) with standard error ±7.35 years. Within the forensic context, sjTREC' levels can be used to estimate the Egyptian individual's age accurately. PMID:27184828
Influence of age in estimating maximal oxygen uptake
de Souza e Silva, Christina G; Franklin, Barry A; Forman, Daniel E; Araújo, Claudio Gil S
2016-01-01
Objective To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO2max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO2 max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. Methods 1850 adults (68% men), aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness (CRF) was assessed relative to sex and age [younger (18 to 35 years), middle-aged (36 to 60 years) and older (> 60 years)]. VO2max [mL·(kg·min)−1] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO2max and related EE were compared among the three age- and sex-specific groups. Results Directly measured VO2max of men and women were 29.5 ± 10.5 mL·(kg·min)−1 and 24.2 ± 9.0 mL·(kg·min)−1 (P < 0.01). EE [mL·(kg·min)−1] and percent errors (%E) for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL·(kg·min)−1, and −0.8 ± 13.1% and −1.7 ± 15.4% (P > 0.05), respectively. EE and %E for each age-group were, respectively, for men: younger = 1.9 ± 4.1 mL·(kg·min)−1 and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL·(kg·min)−1 and 0.4 ± 10.3%, older = −0.2 ± 2.7 mL·(kg·min)−1 and −4.2 ± 16.6% (P < 0.01); and for women: younger = 1.2 ± 3.1 mL·(kg·min)−1 and 2.7 ± 10.0%, middle-aged = 0.7 ± 2.8 mL·(kg·min)−1 and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL·(kg·min)−1 and −9.5 ± 22.4% (P < 0.01). Conclusion VO2max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO2max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured. PMID:27168737
Dental radiographic indicators, a key to age estimation
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
Talabani, Ranjdar M.; Baban, Mohammed T.; Mahmood, Mohammed A.
2015-01-01
Objective: A study was carried out to analyze the efficacy and practical application for age estimation using digital panoramic radiograph to exploit image analysis to obtain metric measurement of morphological parameters of permanent mandibular first molar on Sulaimani population. Materials and Methods: In the present study a population of known age and sex was studied and subjected to digital panoramic radiographic examination. The correlation between the reduction of coronal pulp cavity and chronological age was examined in a sample of 96 individuals distributed into four age groups: 20-29 years (29 cases), 30-39 years (29 cases), 40-49 years (26 cases) and 50-59 years (12 cases). The height (mm) of the crown (CH = coronal height) and the height (mm) of coronal pulp cavity (CPCH = coronal pulp cavity height) of 96 of first molars from all subjects was measured. The tooth–coronal index (TCI) after Ikeda et al. was computed for each tooth and regressed on real age. Results: ANOVA was used to show the strength of relation between the age and TCI (P = 0.0000). The correlation coefficient (r2) was 0.49, which mean there is strong negative linear regression between age and TCI with the r2, regarding predicting age using TCI value, after the following equation calculated, Predicted age = 3.78 – (0.064 TCI) showed that there is no significant difference between real age and estimated age. Conclusion: There is a strong negative liner relationship between TCIs of mandibular first molars with chronological age of Sulaimani population, and age of individuals can therefore be estimated with a good degree of accuracy using regression equations. PMID:26005307
Fetal age estimation using MSCT scans of the mandible.
Minier, Marie; Dedouit, Fabrice; Maret, Delphine; Vergnault, Marion; Mokrane, Fathima-Zohra; Rousseau, Hervé; Adalian, Pascal; Telmon, Norbert; Rougé, Daniel
2014-05-01
The purpose of this study was to examine a documented fetal collection, to carry out morphometric analysis of femoral length and of the mandible, and to develop diagnostic standards for estimating fetal age at death based on multislice computed tomography (MSCT) reconstructions. The sample was composed of 81 fetuses, whose ages were recorded in weeks of amenorrhea (WA) between 20 to 40 WA. The measurements made were femoral length (FL) and six distances and four angles of the mandible. Femoral length was measured in 81 fetuses (39 females and 42 males). Morphometric study of the mandible was carried out in 65 fetuses (31 females and 34 males), as the mandible was missing in 16 fetuses. R software was used for statistical analyses. Coefficient correlation (R(2)) and linear regression formulas were calculated. Intra-observer and inter-observer variabilities were very satisfactory (intra-class correlation coefficient ≥0.95). Our method appears to be reliable and reproducible. Femoral length was most strongly correlated with age (R(2) = 0.9). The measurement of six distances and four mandible angles from four landmark positions showed a correlation similar to the femoral length correlation (R(2) ≥ 0.72). The results of this study agreed with those of the literature. We conclude that the mandible is a reliable indicator for estimating fetal age at death. Moreover, MSCT has been shown to be an innovative and reliable technology for this purpose. PMID:24213737
Accuracy of age estimation of radiographic methods using developing teeth.
Maber, M; Liversidge, H M; Hector, M P
2006-05-15
Developing teeth are used to assess maturity and estimate age in a number of disciplines, however the accuracy of different methods has not been systematically investigated. The aim of this study was to determine the accuracy of several methods. Tooth formation was assessed from radiographs of healthy children attending a dental teaching hospital. The sample was 946 children (491 boys, 455 girls, aged 3-16.99 years) with similar number of children from Bangladeshi and British Caucasian ethnic origin. Panoramic radiographs were examined and seven mandibular teeth staged according to Demirjian's dental maturity scale [A. Demirjian, Dental development, CD-ROM, Silver Platter Education, University of Montreal, Montreal, 1993-1994; A. Demirjian, H. Goldstein, J.M. Tanner, A new system of dental age assessment, Hum. Biol. 45 (1973) 211-227; A. Demirjian, H. Goldstein, New systems for dental maturity based on seven and four teeth, Ann. Hum. Biol. 3 (1976) 411-421], Nolla [C.M. Nolla, The development of the permanent teeth, J. Dent. Child. 27 (1960) 254-266] and Haavikko [K. Haavikko, The formation and the alveolar and clinical eruption of the permanent teeth. An orthopantomographic study. Proc. Finn. Dent. Soc. 66 (1970) 103-170]. Dental age was calculated for each method, including an adaptation of Demirjian's method with updated scoring [G. Willems, A. Van Olmen, B. Spiessens, C. Carels, Dental age estimation in Belgian children: Demirjian's technique revisited, J. Forensic Sci. 46 (2001) 893-895]. The mean difference (+/-S.D. in years) between dental and real age was calculated for each method and in the case of Haavikko, each tooth type; and tested using t-test. Mean difference was also calculated for the age group 3-13.99 years for Haavikko (mean and individual teeth). Results show that the most accurate method was by Willems [G. Willems, A. Van Olmen, B. Spiessens, C. Carels, Dental age estimation in Belgian children: Demirjian's technique revisited, J. Forensic Sci
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
Human age estimation from blood using mRNA, DNA methylation, DNA rearrangement, and telomere length.
Zubakov, Dmitry; Liu, Fan; Kokmeijer, Iris; Choi, Ying; van Meurs, Joyce B J; van IJcken, Wilfred F J; Uitterlinden, André G; Hofman, Albert; Broer, Linda; van Duijn, Cornelia M; Lewin, Jörn; Kayser, Manfred
2016-09-01
Establishing the age of unknown persons, or persons with unknown age, can provide important leads in police investigations, disaster victim identification, fraud cases, and in other legal affairs. Previous methods mostly relied on morphological features available from teeth or skeletal parts. The development of molecular methods for age estimation allowing to use human specimens that possess no morphological age information, such as bloodstains, is extremely valuable as this type of samples is commonly found at crime scenes. Recently, we introduced a DNA-based approach for human age estimation from blood based on the quantification of T-cell specific DNA rearrangements (sjTRECs), which achieves accurate assignment of blood DNA samples to one of four 20-year-interval age categories. Aiming at improving the accuracy of molecular age estimation from blood, we investigated different types of biomarkers. We started out by systematic genome-wide surveys for new age-informative mRNA and DNA methylation markers in blood from the same young and old individuals using microarray technologies. The obtained candidate markers were validated in independent samples covering a wide age range using alternative technologies together with previously proposed DNA methylation, sjTREC, and telomere length markers. Cross-validated multiple regression analysis was applied for estimating and validating the age predictive power of various sets of biomarkers within and across different marker types. We found that DNA methylation markers outperformed mRNA, sjTREC, and telomere length in age predictive power. The best performing model included 8 DNA methylation markers derived from 3 CpG islands reaching a high level of accuracy (cross-validated R(2)=0.88, SE±6.97 years, mean absolute deviation 5.07 years). However, our data also suggest that mRNA markers can provide independent age information: a model using a combined set of 5 DNA methylation markers and one mRNA marker could provide
Age estimation among Brazilians: Younger or older than 18?
Deitos, Alexandre Raphael; Costa, Claudio; Michel-Crosato, Edgard; Galić, Ivan; Cameriere, Roberto; Biazevic, Maria Gabriela Haye
2015-07-01
The age estimation of living or dead individuals is an important part of forensic science because it can be used in various situations, including mass disasters, or for civil or criminal reasons, such as adoption or asylum. Teeth play a major role in this context because they are more resistant than bones in extreme environmental conditions and their development is hardly affected by exogenous or endogenous factors. Because the third molars (3rdM) are still in development from the age of 14, they are useful for determining whether an individual has reached the legal age of 18 years. This study aims to verify the method of Cameriere et al. (2008) in Brazil to discriminate whether an individual is under or over 18 years from the maturity index of the 3rdM (I3m). The analysis of 444 panoramic radiographs resulted in a sensitivity of 78.3%, a specificity of 85.1% and a correct classification of 87%. Significant differences in sexual dimorphism in the early mineralization of males were found only for the average age with I3m ≥ 0.08, except for the range (0.7, 0.9). Due to the high miscegenation ratio of the Brazilian population the ancestry was not one of the studied variables. The method is suitable for estimating adulthood for forensic purposes in Brazil, although it must be applied carefully and judiciously. We recommend a combination of several methods that are available to increase accuracy as well as the establishment of different parameters that are likely to determine whether a person is more or less than 18 years of age, depending on the different legal requirements, whether civil or criminal. PMID:26048509
Estimation of Heterogeneity in Diagnostic Parameters of Age-related Diseases.
Blokh, David; Stambler, Ilia
2014-08-01
The heterogeneity of parameters is a ubiquitous biological phenomenon, with critical implications for biological systems functioning in normal and diseased states. We developed a method to estimate the level of objects set heterogeneity with reference to particular parameters and applied it to type II diabetes and heart disease, as examples of age-related systemic dysfunctions. The Friedman test was used to establish the existence of heterogeneity. The Newman-Keuls multiple comparison method was used to determine clusters. The normalized Shannon entropy was used to provide the quantitative evaluation of heterogeneity. There was obtained an estimate for the heterogeneity of the diagnostic parameters in healthy subjects, as well as in heart disease and type II diabetes patients, which was strongly related to their age. With aging, as with the diseases, the level of heterogeneity (entropy) was reduced, indicating a formal analogy between these phenomena. The similarity of the patterns in aging and disease suggested a kind of "early aging" of the diseased subjects, or alternatively a "disease-like" aging process, with reference to these particular parameters. The proposed method and its validation on the chronic age-related disease samples may support a way toward a formal mathematical relation between aging and chronic diseases and a formal definition of aging and disease, as determined by particular heterogeneity (entropy) changes. PMID:25110613
5 CFR 1650.41 - How to obtain an age-based withdrawal.
Code of Federal Regulations, 2014 CFR
2014-01-01
... record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to initiate a request. A participant's ability to complete an age-based withdrawal on the Web will depend...
5 CFR 1650.41 - How to obtain an age-based withdrawal.
Code of Federal Regulations, 2010 CFR
2010-01-01
... record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to initiate a request. A participant's ability to complete an age-based withdrawal on the Web will depend...
5 CFR 1650.41 - How to obtain an age-based withdrawal.
Code of Federal Regulations, 2013 CFR
2013-01-01
... record keeper a properly completed paper TSP age-based withdrawal request form or use the TSP Web site to initiate a request. A participant's ability to complete an age-based withdrawal on the Web will depend...
NASA Astrophysics Data System (ADS)
Hill, Mimi J.; Pan, Yongxin; Davies, Ceri J.
2008-08-01
Here we present microwave palaeointensity results from 89 sister samples from the study of Zhu et al. [Zhu, R., Pan, Y., He, H., Qin, H., Ren, S., 2008. Palaeomagnetism and 40Ar/ 39Ar age from a Cretaceous volcanic sequence, Inner Mongolia, China: implications for the field variation during the Cretaceous normal superchron. Phys. Earth Planet. Int., 169, 59-75] who carried out Thellier palaeointensity analysis as part of their integrated palaeomagnetic and 40Ar/ 39Ar dating study of Cretaceous lava from the Suhungtu section, Inner Mongolia, China. Additionally, a comprehensive rock magnetic investigation has been carried out in order to determine the mineralogy and hence the validity of assuming that the remanence is a thermal remanent magnetisation (TRM). The microwave results are of apparent high quality and give flow mean palaeointensity estimates ranging from 13 to 49 μT corresponding to virtual dipole moment (VDM) estimates ranging from 2.5 to 8.9 × 10 22 Am 2, and an overall mean VDM of 5.5 ± 1.9 × 10 22 Am 2 for the 24 flows (aged 110.6 ± 0.1 Ma). When the microwave results (using the perpendicular applied field method with partial microwave thermal remanence (pT MRM) and pT MRM tail checks) are compared to those obtained with the Thellier method (Coe version with pTRM but not tail checks, and heating in argon atmosphere) differences are seen at the sample, flow and palaeomagnetic unit level however, the overall means and spread in palaeointensity estimates are consistent. Some discrepancy is due to the differing sized sample sets and sample inhomogeneity but discrepancy is also interpreted to be due to the differing protocols, methodology, plus the subjectivity in interpretation. Considering only those results that are consistent to within 20% the spread in palaeointensity estimates remains. There is substantial rock magnetic evidence from progressive heating in air and argon experiments (both showing irreversible thermomagnetic behaviour) as well as
NASA Astrophysics Data System (ADS)
Ohtake, Hideaki; Gari da Silva Fonseca, Joao, Jr.; Takashima, Takumi; Oozeki, Takashi; Yamada, Yoshinori
2014-05-01
Many photovoltaic (PV) systems have been installed in Japan after the introduction of the Feed-in-Tariff. For an energy management of electric power systems included many PV systems, the forecast of the PV power production are useful technology. Recently numerical weather predictions have been applied to forecast the PV power production while the forecasted values invariably have forecast errors for each modeling system. So, we must use the forecast data considering its error. In this study, we attempted to estimate confidence intervals for hourly forecasts of global horizontal irradiance (GHI) values obtained from a mesoscale model (MSM) de-veloped by the Japan Meteorological Agency. In the recent study, we found that the forecasted values of the GHI of the MSM have two systematical forecast errors; the first is that forecast values of the GHI are depended on the clearness indices, which are defined as the GHI values divided by the extraterrestrial solar irradiance. The second is that forecast errors have the seasonal variations; the overestimation of the GHI forecasts is found in winter while the underestimation of those is found in summer. The information of the errors of the hourly GHI forecasts, that is, confidence intervals of the forecasts, is of great significance for planning the energy management included a lot of PV systems by an electric company. On the PV systems, confidence intervals of the GHI forecasts are required for a pinpoint area or for a relatively large area control-ling the power system. For the relatively large area, a spatial-smoothing method of the GHI values is performed for both the observations and forecasts. The spatial-smoothing method caused the decline of confidence intervals of the hourly GHI forecasts on an extreme event of the GHI forecast (a case of large forecast error) over the relatively large area of the Tokyo electric company (approximately 68 % than for a pinpoint forecast). For more credible estimation of the confidence
Estimation of fetal gestational age from ultrasound images
NASA Astrophysics Data System (ADS)
Salari, Valiollah
1992-06-01
Estimation of fetal gestational age, weight, and determination of fetal growth from the measurements of certain parameters of fetal head, abdomen, and femur have been well established in prenatal sonography. The measurements are made from the two dimensional, B- mode, ultrasound images of the fetus. The most common parameters measured are, biparietal diameter, occipital frontal diameter, head circumference, femur diaphysis length, and abdominal circumference. Since the fetal head has an elliptical shape and the femur has a linear shape, fitting the ellipse on the image of the fetal head, a line on the image of the femur are the tasks of image processing which are discussed in this paper.
NASA Astrophysics Data System (ADS)
Irving, James D.
Crosshole ground-penetrating radar (GPR) travel-time tomography is a popular geophysical technique for characterization of the shallow subsurface in environmental applications. With this technique, a critical factor determining the resolution of the velocity images obtained is the angular ray coverage of the subsurface region between the boreholes; when travel-time data representing a narrow range of ray angles are used for the tomography reconstruction, the resulting images contain undesirable directional smearing. Here, I investigate the problem that, even when the crosshole GPR survey geometry offers the potential for high-resolution imaging due to wide angular ray coverage of the inter-borehole region, two significant issues are commonly encountered when attempting to take advantage of this coverage. First, travel times corresponding to high-angle ray paths are often extremely difficult to pick because of low signal-to-noise ratios in the data. Secondly, even when high-angle travel-time data can be reliably determined, they often appear to be incompatible with the lower-angle data available, and tend to cause strong numerical artifacts when included in inversions. To address the high-angle picking problem noted above, I develop a method for determining first-break times in crosshole GPR data using cross-correlations. High-quality reference waveforms for this technique are obtained from the data through the stacking of common-ray-angle gathers. To address the incompatibility issue with high-angle data, I first develop finite-difference time-domain (FDTD) numerical modeling codes that allow for the determination of realistic crosshole GPR antenna current distributions, and the modeling of transmitted and received waveforms in heterogeneous media. Using these codes, I then find that the high-angle incompatibility issue is likely the result of assuming that first-arriving energy always travels directly between the antenna centers; at high transmitter
Cardoso, Hugo F V; Abrantes, Joana; Humphrey, Louise T
2014-09-01
Age at death in immature human skeletal remains has been estimated from the diaphyseal length of the long bones, but few studies have actually been designed specifically for the purpose of age estimation and those which have, show important caveats. This study uses regression and classical calibration to model the relationship between age and diaphyseal length of the six long bones, in a sample of 184 known sex and age individuals (72 females and 112 males), younger than 13 years of age, selected from Portuguese and English skeletal collections. Age estimation models based on classical calibration were obtained for each of the six long bones, and separately for each sex and for the sexes combined, and also for the entire sample and when it is subdivided into two subsamples at the age of 2 years. Comparisons between inverse and classical calibration show there is a systematic bias in age estimations obtained from inverse calibration. In the classical calibration models, the length of the femur provides the most accurate estimates of age. Age estimates are more accurate for the male subsample and for individuals under the age of 2 years. These results and a test of previously published methods caution against inverse calibration as a technique for developing age estimation methods even from the immature skeleton. Age estimation methods developed using cemetery collections of identified human skeletons should not be uncritically applied to present-day populations from the same region since many populations have experienced dramatic secular trends in growth and adult height over the last century. PMID:24126574
The study on telomere length for age estimation in a Thai population.
Srettabunjong, Supawon; Satitsri, Saravut; Thongnoppakhun, Wanna; Tirawanchai, Nednapis
2014-06-01
Age is one of the key parameters in establishing a physical characteristic profile of an individual. For biological evidence left in crime scenes such as blood, saliva, hair, etc, the evidence owner's age can be determined only by DNA extracted from these materials. Previous researches have found that there are certain DNA regions with specialized characteristic and function called telomere being able to predict age. The present study was to determine the correlation between telomere length and age as well as the effect of sex on the correlation and to create linear regression equation for age estimation in Thai population for forensic purposes. Blood samples obtained from unrelated healthy Thai fresh cadavers without anatomical organ abnormalities were used in this study. All cadaver subjects underwent the postmortem examination in jurisdiction of the Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, and Institute of Forensic Medicine, Police General Hospital. Fifty blood samples from both sexes of all ages divided into 6 groups for equal age distribution (0-11, 12-23, 24-35, 36-47, 48-59, and 60 years old and older) were collected for a total of 100 samples. The extracted genomic DNA samples were then subjected to telomere length estimation by terminal restriction fragment (TRF) assay. The results showed that the mean TRF length was inversely correlated with age (r = -0.625), and sex did not have a statistically significant influence on the association between age and mean TRF length (P > 0.05). The obtained linear regression equation was y = 113.538 ± 9.604 - 0.012 × (R = 0.391; P < 0.001). However, the correlation was too low to be used for age estimation with high certainty and a possible reason for this in part would be the postmortem DNA degradation at some level, even using fresh cadaver blood, and other biological factors such as ethnicity and DNA sources. Roughly, those individuals who had a mean TRF length
Cardoso, Hugo F V
2007-10-01
Dental age assessments are widely used to estimate age of immature skeletal remains. Most methods have relied on fractional stages of tooth emergence and formation, particularly of the permanent dentition, for predicting the age of infants and very young children. In this study, the accuracy of regression equations of developing deciduous tooth length for age estimation (Liversidge et al.) is tested on a sample of 30 Portuguese subadult skeletons of known age at death. Overall the method shows high accuracy and the average difference between estimated and chronological age is between 0.20 and -0.14 years when using single teeth, and 0.06 years, when using all available teeth. However, there is a tendency for the deciduous molars to provide overestimates of chronological age. Results show that age estimates can be obtained within +/-0.10 years with a 95% confidence interval when several teeth are used. Overall between-tooth agreement in age estimates decreases with increasing age but there is less variability of estimates with more teeth contributing to overall mean age. One seemingly limitation of this method may be the fact that it was developed by combining the maxillary and mandibular teeth. The other is related to the accuracy with which radiographic tooth length can be used as a valid surrogate for actual tooth length. Nevertheless, the advantages of this metric method surpass the limitations of chronologies based on stages of dental development. PMID:17174050
Age estimation in Indians from pulp/tooth area ratio of mandibular canines.
Babshet, Medha; Acharya, Ashith B; Naikmasur, Venkatesh G
2010-04-15
In India, age estimation of living individuals is gaining importance, particularly in cases of child labour, ascertaining majority status and to assess disputed age in criminals. Previous studies on adult age prediction in Indians have focused on histological parameters, which are invasive in nature and not feasible in the living. Methods for age estimation in living adults make use of radiographs to indirectly measure the rate of secondary dentine deposition and studies have focused on ratios of linear measurements rather than absolute dimensions per se. Recently, the ratio of the pulp/tooth area of canines was suggested by a group in Italy who developed regression formulas for age estimation. The present study has assessed the usefulness of one of the formulas on an Indian sample and also examined the use of an India-specific equation in age prediction. Intraoral periapical digital radiographs of mandibular canines were obtained from 143 individuals (aged 20-70 years) using the paralleling technique; pulp and tooth areas were measured using a commercially available computer software programme and the pulp/tooth area ratio was computed. Age was calculated using the Italian formula which revealed a mean absolute error (MAE) of 11.01 years in Indians, an error recognisably greater than the 4.38 years reported in the Italian sample. The divergence may be explained on account of population differences that exist between Italians and Indians as well as variation in the pattern of secondary dentine deposition in Indians. The Indian formula derived (age=64.413-(195.265 x PTR), where PTR is the pulp/tooth area ratio) was applied on a control group of 35 radiographs. The Italian formula was also applied on the control sample to ascertain if the Indian formula markedly improved age prediction. No apparent difference was observed between the two (MAE was 10.76 and 11.58 years, respectively, using the Indian and Italian formula) however, the Indian formula had a tendency to
ERIC Educational Resources Information Center
Savalei, Victoria; Rhemtulla, Mijke
2012-01-01
Fraction of missing information [lambda][subscript j] is a useful measure of the impact of missing data on the quality of estimation of a particular parameter. This measure can be computed for all parameters in the model, and it communicates the relative loss of efficiency in the estimation of a particular parameter due to missing data. It has…
A method for estimating gestational age of fetal remains based on long bone lengths.
Carneiro, Cristiana; Curate, Francisco; Cunha, Eugénia
2016-09-01
The estimation of gestational age (GA) in fetal human remains is important in forensic settings, particularly to assess fetal viability, in addition to often being the only biological profile parameter that can be assessed with some accuracy for non-adults. The length of long bone diaphysis is one of the most frequently used methods for fetal age estimation. The main objective of this study was to present a simple and objective method for estimating GA based on the measurements of the diaphysis of the femur, tibia, fibula, humerus, ulna, and radius. Conventional least squares regression equations (classical and inverse calibration approaches) and quick reference tables were generated. A supplementary objective was to compare the performance of the new formulae against previously published models. The sample comprised 257 fetuses (136 females and 121 males) with known GA (between 12 and 40 weeks) and was selected based on clinical and pathological information. All measurements were performed on radiographic images acquired in anonymous clinical autopsy records from spontaneous and therapeutic abortions in two Portuguese hospitals. The proposed technique is straightforward and reproducible. The models for the GA estimation are exceedingly accurate and unbiased. Comparisons between inverse and classical calibration show that both perform exceptionally well, with high accuracy and low bias. Also, the newly developed equations generally outperform earlier methods of GA estimation in forensic contexts. Quick reference tables for each long bone are now available. The obtained models for the estimation of gestational age are of great applicability in forensic contexts. PMID:27251047
Application of modified reverse panoramic radiograph on lambdoid suture for age estimation
Dwivedy, Shweta; Sah, Kunal; Sinha, Shruti
2015-01-01
Background Cranial suture closure has long been recognized as a character of human development related to aging. For this reason, it has been utilized for various forensic and archaeological studies to determine the age of an unidentified/or skeletonized individuals. Various cadaveric studies have established the role of lambdoid suture in age estimation, but not routinely practiced. The objective is to establish if any correlation exists between individual’s age and lambdoid sutures closure status (ectocranially) in mortals through modified reverse panoramic radiograph (RPRg). Methods Total number of 85 subjects, 25 years and beyond were included in the study, and divided into four groups with an age interval of 10 years. Assessment of lambdoid suture closure was done according to Frederic Rating Scale on modified RPRg. Data obtained was subjected to statistical analysis using Spearman’s correlation test. Results A significant difference was observed between the age group and suture closure. Correlation coefficient of 0.570 was obtained, and was interpreted as a good correlation between the age and suture closure status with a P value of <0.001. Conclusions Lambdoid suture can be very effective and practical tool for age assessment in mortals through modified RPRg (ectocranially). PMID:26435915
Ultrasonographic estimation of prostate size in normal dogs and relationship to bodyweight and age.
Atalan, G; Holt, P E; Barr, F J
1999-03-01
A study was undertaken to establish the ranges of prostate dimensions, weight and volume in mature normal dogs and thus provide information which would allow differentiation from normality of size changes associated with disease. The study was performed on 154 healthy adult male entire dogs. Each prostate was imaged ultrasonographically and standard longitudinal and transverse sections were obtained. Prostate length (L), depth on longitudinal (DL) and transverse sections (DT) and width (W) were measured. Prostatic volume and weight were estimated according to formulae derived previously. There were statistically significant correlations between bodyweight or age and L, DL, DT and W. There were also significant correlations between estimated prostatic weight or volume and bodyweight, age, L, DL, DT and W. Formulae were derived to express the relationships between prostate size (weight or volume) and age or bodyweight. PMID:10200922
Humm, J L; Macklis, R M; Lu, X Q; Yang, Y; Bump, K; Beresford, B; Chin, L M
1995-01-01
In order to better predict and understand the effects of radiopharmaceuticals used for therapy, it is necessary to determine more accurately the radiation absorbed dose to cells in tissue. Using thin-section autoradiography, the spatial distribution of sources relative to the cells can be obtained from a single section with micrometre resolution. By collecting and analysing serial sections, the 3D microscopic distribution of radionuclide relative to the cellular histology, and therefore the dose rate distribution, can be established. In this paper, a method of 3D reconstruction of serial sections is proposed, and measurements are reported of (i) the accuracy and reproducibility of quantitative autoradiography and (ii) the spatial precision with which tissue features from one section can be related to adjacent sections. Uncertainties in the activity determination for the specimen result from activity losses during tissue processing (4-11%), and the variation of grain count per unit activity between batches of serial sections (6-25%). Correlation of the section activity to grain count densities showed deviations ranging from 6-34%. The spatial alignment uncertainties were assessed using nylon fibre fiduciary markers incorporated into the tissue block, and compared to those for alignment based on internal tissue landmarks. The standard deviation for the variation in nylon fibre fiduciary alignment was measured to be 41 microns cm-1, compared to 69 microns cm-1 when internal tissue histology landmarks were used. In addition, tissue shrinkage during histological processing of up to 10% was observed. The implications of these measured activity and spatial distribution uncertainties upon the estimate of cellular dose rate distribution depends upon the range of the radiation emissions. For long-range beta particles, uncertainties in both the activity and spatial distribution translate linearly to the uncertainty in dose rate of < 15%. For short-range emitters (< 100
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.
An Age Estimate for the beta Pictoris Analog HR 4796A
NASA Astrophysics Data System (ADS)
Stauffer, John R.; Hartmann, Lee W.; Barrado y Navascues, David
1995-12-01
We have obtained a high-resolution, moderate signal-to-noise spectrum for the M dwarf companion to HR 4796A, an AO star with a β Pictoris-type IR excess. The spectrum of the M star shows an extraordinarily strong lithium 6708 Å absorption line with an equivalent width of 550 mÅ. Age estimates derived from the lithium strength and from pre-main-sequence isochrone fitting indicate an age of about 8 ± 2 Myr for HR 4796B. Assuming this age is also applicable to HR 4796A, we conclude that HR 4796A is a relatively normal A star seen at an unusual time (i.e., when it is very young) rather than an A star of "average" age which has somehow managed to retain or acquire a dense, circumstellar disk, in rough agreement with conclusions reached previously by Jura et al.
The influence of random element displacement on DOA estimates obtained with (Khatri-Rao-)root-MUSIC.
Inghelbrecht, Veronique; Verhaevert, Jo; van Hecke, Tanja; Rogier, Hendrik
2014-01-01
Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to random errors in the array geometry. Therefore, we propose a stochastic collocation method that relies on a generalized polynomial chaos expansion to connect the statistical distribution of random position errors to the resulting distribution of the DOA estimates. We apply this technique to the conventional root-MUSIC and the Khatri-Rao-root-MUSIC methods. According to Monte-Carlo simulations, this novel approach yields a speedup by a factor of more than 100 in terms of CPU-time for a one-dimensional case and by a factor of 56 for a two-dimensional case. PMID:25393783
NASA Astrophysics Data System (ADS)
Crow, Wade T.; Lei, Fangni; Hain, Christopher; Anderson, Martha C.; Scott, Russell L.; Billesbach, David; Arkebauer, Timothy
2015-10-01
Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of SM/LH coupling strength using ground-based observational data is potentially compromised by the impact of independent SM and LH measurements errors. Here we apply a new statistical technique to acquire estimates of one-way SM/LH coupling strength which are nonbiased in the presence of random error using a triple collocation approach based on leveraging the simultaneous availability of independent SM and LH estimates acquired from (1) LSMs, (2) satellite remote sensing, and (3) ground-based observations. Results suggest that LSMs do not generally overestimate the strength of one-way surface SM/LH coupling.
The Influence of Random Element Displacement on DOA Estimates Obtained with (Khatri–Rao-)Root-MUSIC
Inghelbrecht, Veronique; Verhaevert, Jo; van Hecke, Tanja; Rogier, Hendrik
2014-01-01
Although a wide range of direction of arrival (DOA) estimation algorithms has been described for a diverse range of array configurations, no specific stochastic analysis framework has been established to assess the probability density function of the error on DOA estimates due to random errors in the array geometry. Therefore, we propose a stochastic collocation method that relies on a generalized polynomial chaos expansion to connect the statistical distribution of random position errors to the resulting distribution of the DOA estimates. We apply this technique to the conventional root-MUSIC and the Khatri-Rao-root-MUSIC methods. According to Monte-Carlo simulations, this novel approach yields a speedup by a factor of more than 100 in terms of CPU-time for a one-dimensional case and by a factor of 56 for a two-dimensional case. PMID:25393783
Schmalz, K; Larwa, L
1997-02-01
This study surveyed 265 parents of children in kindergarten through third grade in an urban New Jersey public school to determine problems encountered in obtaining regular immunizations. The most frequent reasons parents failed to obtain immunizations were cost, lesser use of WIC and AFDC, and lower perceived susceptibility of child to consequences of disease. PMID:9146212
Aydin, Zeynep; Marcussen, Thomas; Ertekin, Alaattin Selcuk; Oxelman, Bengt
2014-01-01
Coalescent-based inference of phylogenetic relationships among species takes into account gene tree incongruence due to incomplete lineage sorting, but for such methods to make sense species have to be correctly delimited. Because alternative assignments of individuals to species result in different parametric models, model selection methods can be applied to optimise model of species classification. In a Bayesian framework, Bayes factors (BF), based on marginal likelihood estimates, can be used to test a range of possible classifications for the group under study. Here, we explore BF and the Akaike Information Criterion (AIC) to discriminate between different species classifications in the flowering plant lineage Silene sect. Cryptoneurae (Caryophyllaceae). We estimated marginal likelihoods for different species classification models via the Path Sampling (PS), Stepping Stone sampling (SS), and Harmonic Mean Estimator (HME) methods implemented in BEAST. To select among alternative species classification models a posterior simulation-based analog of the AIC through Markov chain Monte Carlo analysis (AICM) was also performed. The results are compared to outcomes from the software BP&P. Our results agree with another recent study that marginal likelihood estimates from PS and SS methods are useful for comparing different species classifications, and strongly support the recognition of the newly described species S. ertekinii. PMID:25216034
Technology Transfer Automated Retrieval System (TEKTRAN)
Land surface models (LSMs) are often applied to predict the one-way coupling strength between surface soil moisture (SM) and surface latent heat (LH) flux. However, the ability of LSMs to accurately represent such coupling has not been adequately established. Likewise, the estimation of one-way SM/L...
Mallar, Kavya B; Girish, HC; Murgod, Sanjay; Kumar, BN Yathindra
2015-01-01
Background: Age estimation is an important factor in the identification of an individual in forensic science. Research indicates that cemental annulations may be used more reliably than other morphological or histological traits of human skeleton for age estimation. Materials and Methods: Twenty-five teeth were sectioned longitudinally, and twenty-five teeth were cross-sectioned at the mid portion of the root. Sections were ground, mounted and viewed under a bright light microscope. The area selected for counting was photographed under ×10 objective, magnified 5 times; cemental lines were counted and added to the eruption age of that patient, to obtain the chronological age. The statistical software SAS 9.2, SPSS 15.0, Stata 10.1, MedCalc 9.0.1, Systat 12.0 and R environment ver.2.11.1 were used for the analysis of the data. Results: The P value comparing actual age and calculated age using longitudinal sections is moderately significant and the P value comparing actual age and calculated age in the age group of <30 years is significant. Interpretation and Conclusion: The middle third of tooth root was most suitable to count annulations. The cross sections are easier to count but longitudinal sections give more appropriate results on age estimation. Though the procedure predicts under assessment of age in the younger age group and over assessment of age in the older age group, it provides a close estimate of the actual age of an individual. It can be correlated with other age estimation methods for better reliability. PMID:26980973
A Probabilistic Approach to Obtaining Limiting Estimates of Radionuclide Concentrations in Biota
Higley, Kathryn A.; Domotor, S L.; Antonio, Ernest J. )
2003-06-06
The U.S. Department of Energy has developed a graded approach fo assessing compliance with radiation standards for protection of biota. Limiting concentrations of radionuclides in water, soil, and sediment were derived for twenty-three radionuclides. Four organisms types (aquatic animals, rparian animals, terrestrial animals, and terrestrial plants) were selected as the basis for methods development. While data are available for aquatic animals and terrestrial plants, less information is available for terrestrial and riparian organisms. Two methods were examined for their ability to provide estimates of organism:soil and organism:water concentration factors in lieu of measured data. The kinetic/allometric approach combined with an uncertainty analysis apprach was able to estimate concentration factors across multiple species with limited input data.
A probabilistic approach to obtaining limiting estimates of radionuclide concentration in biota.
Higley, Kathryn A; Domotor, Stephen L; Antonio, Ernest J
2003-01-01
The US Department of Energy has developed a graded approach for evaluating radiation doses to biota. Limiting concentrations of radionuclides in water, soil, and sediment were derived for twenty-three radionuclides. Four organism types (aquatic animals, riparian animals, terrestrial animals, and terrestrial plants) were selected as the basis for method development. While environmental transfer data needed for deriving biota tissue concentrations are available for aquatic animals and terrestrial plants, less information is available for terrestrial and riparian organisms. Two methods were applied and examined for their ability to provide estimates of organism:soil or organism:water concentration factors in lieu of measured data. The kinetic/allometric approach combined with a parameter uncertainty analysis provides a needed method to estimate concentration factors across multiple species with limited input data. PMID:12590071
The estimated prevalence and incidence of late stage age related macular degeneration in the UK
Jarrar, Zakariya; Wormald, Richard; Cook, Derek G; Fletcher, Astrid E; Rudnicka, Alicja R
2012-01-01
Background UK estimates of age related macular degeneration (AMD) occurrence vary. Aims To estimate prevalence, number and incidence of AMD by type in the UK population aged ≥50 years. Methods Age-specific prevalence rates of AMD obtained from a Bayesian meta-analysis of AMD prevalence were applied to UK 2007–2009 population data. Incidence was estimated from modelled age-specific prevalence. Results Overall prevalence of late AMD was 2.4% (95% credible interval (CrI) 1.7% to 3.3%), equivalent to 513 000 cases (95% CrI 363 000 to 699 000); estimated to increase to 679 000 cases by 2020. Prevalences were 4.8% aged ≥65 years, 12.2% aged ≥80 years. Geographical atrophy (GA) prevalence rates were 1.3% (95% CrI 0.9% to 1.9%), 2.6% (95% CrI 1.8% to 3.7%) and 6.7% (95% CrI 4.6% to 9.6%); neovascular AMD (NVAMD) 1.2% (95% CrI 0.9% to 1.7%), 2.5% (95% CrI 1.8% to 3.4%) and 6.3% (95% CrI 4.5% to 8.6%), respectively. The estimated number of prevalent cases of late AMD were 60% higher in women versus men (314 000 cases in women, 192 000 men). Annual incidence of late AMD, GA and NVAMD per 1000 women was 4.1 (95% CrI 2.4% to 6.8%), 2.4 (95% CrI 1.5% to 3.9%) and 2.3 (95% CrI 1.4% to 4.0%); in men 2.6 (95% CrI 1.5% to 4.4%), 1.7 (95% CrI 1.0% to 2.8%) and 1.4 (95% CrI 0.8% to 2.4%), respectively. 71 000 new cases of late AMD were estimated per year. Conclusions These estimates will guide health and social service provision for those with late AMD and enable estimation of the cost of introducing new treatments. PMID:22329913
Technology Transfer Automated Retrieval System (TEKTRAN)
Data on individual daily feed intake, bi-weekly BW, and carcass composition were obtained on 1,212 crossbred steers, in Cycle VII of the Germplasm Evaluation Project at the U.S. Meat Animal Research Center. Within animal regressions of cumulative feed intake and BW on linear and quadratic days on fe...
NASA Astrophysics Data System (ADS)
He, X.; Vejen, F.; Sonnenborg, T. O.; Jensen, K. H.
2015-12-01
Precipitation is the main driving force for the terrestrial water cycle and therefore plays a critical role in determining the water budget at catchment scale. Traditionally, rain gauges are used to measure precipitation on the ground surface for hydrological modeling. However, the number of rain gauges in Denmark has significantly decreased in recent years, and it is no longer possible to represent the spatial heterogeneity of rainfall only by interpolating the rain gauge data given the current gauge density in Skjern catchment, Denmark. The quality of simulated hydrological patterns using such rain gauge based products is visibly decreased. Weather radar scans the atmosphere with large areal coverage and high spatial and temporal resolution, which makes it an ideal tool to overcome this problem. The Danish Meteorological Institute (DMI) operates C-band radars over the country. It has been previously attempted to use the single-polarization radar located at Rømø to estimate precipitation in Skjern catchment; however, the hydrological improvement by adding the single-polarization radar data was marginal due to many restrictions. A new radar located at Virring with upgraded dual-polarization technology opens new possibilities to further improve the precipitation estimation at Skjern catchment. New parameters retrieved from the Virring radar will be used to develop more advanced quantitative precipitation estimation algorithms which is an important supplement to the existing algorithm called ARNE. The development of the new algorithm will be based on the Open Source Library for Weather Radar Data Processing (WRadLib). The results of hydrological models using such product are expected to better close the water budget and improve the simulated hydrological pattern such as the land surface temperature.
Estimation of Young's modulus of pharmaceutical tablet obtained by terahertz time-delay measurement.
Peiponen, Kai-Erik; Bawuah, Prince; Chakraborty, Mousumi; Juuti, Mikko; Zeitler, J Axel; Ketolainen, Jarkko
2015-07-15
In this paper, it is suggested that Young's modulus of pharmaceutical tablets with different porosity can be estimated from terahertz (THz) pulse time delay. We demonstrate such a possibility using a training set of tablets compressed from starch acetate. Once the mechanical properties are taught to the THz measurement system, using an ideal tablet as a reference, it is possible to get information about the Young's modulus of the tablet. Here, we show that there are optical counterparts of classical mechanical laws that couple the Young's modulus and porosity of the tablet. PMID:25934425
Estimation of fracture toughness of cast stainless steels during thermal aging in LWR systems
Chopra, O.K. )
1991-06-01
A procedure and correlations are presented for predicting the change in fracture toughness of cast stainless steel components due to thermal aging during service in light water rectors (LWRs) at 280--330{degrees}C (535--625{degrees}F). The fracture toughness J-R curve and Charpy-impact energy of aged cast stainless steels are estimated from known mineral in formation. Fracture toughness of a specific cast stainless steel is estimated from the extent and kinetics of thermal embrittlement. The extent of thermal embrittlement is characterized by the room-temperature normalized'' Charpy-impact energy. A correlation for the extent of embrittlement at saturation,'' i.e., the minimum impact energy that would be achieved for the material after long-term aging, is given in terms of a material parameter, {Phi}, which is determined from the chemical composition. The fracture toughness J-R curve for the material is then obtained from correlations between room-temperature Charpy-impact energy and fracture toughness parameters. Fracture toughness as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which is determined from chemical composition. A common lower-bound'' J-R curve for cast stainless steels with unknown chemical composition is also defined for a given material specification, ferrite content, and temperature. Examples for estimating impact strength and fracture toughness of cast stainless steel components during reactor service are describes. 24 refs., 39 figs., 2 tabs.
Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi
2015-01-01
This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and −17%, respectively. PMID:25860071
Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi
2015-01-01
This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and -17%, respectively. PMID:25860071
Can you hear my age? Influences of speech rate and speech spontaneity on estimation of speaker age
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
Can you hear my age? Influences of speech rate and speech spontaneity on estimation of speaker age.
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
Evaluation of third molar development in the estimation of chronological age.
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. PMID:26164359
Estimation of error limits for cerebral blood flow values obtained from xenon-133 clearance curves
Ryding, E.
1989-02-01
I provide the theoretical basis for an error calculus for measurements of cerebral blood flow using a freely diffusible tracer substance such as xenon-133. The use of the error calculus is exemplified by a study of the effect on the error margins in measurements of gray matter blood flow from flow level, relative weight of the gray matter compartment, and use of the earliest parts of the clearance curves. The clinical value of the error calculus is illustrated by its ability to separate different sources of measurement error. As a consequence, it is possible to optimize the method for blood flow calculation from the clearance curves, depending on the type of cerebral blood flow measurement. I show that if a true picture of the regional gray matter blood flow distribution is sought, the earliest part of the clearance curves should be used. This does, however, increase the error in the estimate of the average cerebral blood flow value.
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.
NASA Astrophysics Data System (ADS)
Dlubac, Katherine; Knight, Rosemary; Song, Yi-Qiao; Bachman, Nate; Grau, Ben; Cannia, Jim; Williams, John
2013-04-01
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.
Chopra, O. K.; Energy Technology
1994-10-05
This report presents a revision of the procedure and correlations presented earlier in NUREG/CR-4513, ANL-90/42 (June 1991) for predicting the change in mechanical properties of cast stainless steel components due to thermal aging during service in light water reactors at 280-330 C (535-625 F). The correlations presented in this report are based on an expanded data base and have been optimized with mechanical-property data on cast stainless steels aged up to {approx}58,000 h at 290-350 C (554-633 F). The correlations for estimating the change in tensile stress, including the Ramberg/Osgood parameters for strain hardening, are also described. The fracture toughness J-R curve, tensile stress, and Charpy-impact energy of aged cast stainless steels are estimated from known material information. Mechanical properties of a specific cast stainless steel are estimated from the extent and kinetics of thermal embrittlement. Embrittlement of cast stainless steels is characterized in terms of room-temperature Charpy-impact energy. The extent or degree of thermal embrittlement at 'saturation,' i.e., the minimum impact energy that can be achieved for a material after long-term aging, is determined from the chemical composition of the steel. Charpy-impact energy as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which are also determined from the chemical composition. The initial impact energy of the unaged steel is required for these estimations. Initial tensile flow stress is needed for estimating the flow stress of the aged material. The fracture toughness J-R curve for the material is then obtained by correlating room-temperature Charpy-impact energy with fracture toughness parameters. The values of JIC are determined from the estimated J-R curve and flow stress. A common 'predicted lower-bound' J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, range of
Estimating permeability using median pore-throat radius obtained from mercury intrusion porosimetry
NASA Astrophysics Data System (ADS)
Gao, Zhiye; Hu, Qinhong
2013-04-01
Mercury intrusion porosimetry (MIP) has been widely used to characterize the pore structure for various types of porous media. Several relationships between permeability and pore structure information (e.g., porosity and pore-size distribution) have been developed in the literature. This work is to introduce a new, and simpler, empirical equation to predict permeability by solely using the median pore-throat radius (r50), which is the pore-throat radius corresponding to 50% mercury saturation. The total of 18 samples used in this work have a wide range of permeability, from 10-6 to 103 mD, which makes the new equation more applicable. The predicted permeabilities by using the new equation are comparable with permeability values obtained from other measurement methods, as shown from ten samples with permeability data measured with nitrogen.
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 ...
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…
Kaur, Prabhpreet; Astekar, Madhusudan; Singh, Jappreet; Arora, Karandeep Singh; Bhalla, Gagandeep
2015-01-01
Context: The identification of living or deceased persons using unique traits and characteristics of the teeth and jaws is a cornerstone of forensic science. Teeth have been used to estimate age both in the young and old, as well as in the living and dead. Gradual structural changes in teeth throughout life are the basis for age estimation. Tooth cementum annulation (TCA) is a microscopic method for the determination of an individual's age based on the analysis of incremental lines of cementum. Aim: To compare ages estimated using incremental lines of cementum as visualized by bright field microscopy, polarized microscopy, and phase contrast microscopy with the actual age of subject and to determine accuracy and feasibility of the method used. Materials and Methods: Cementum annulations of 60 permanent teeth were analyzed after longitudinal ground sections were made in the mesiodistal plane. The incremental lines were counted manually using a light, polarized and phase contrast microscopy. Ages were estimated and then compared with the actual age of individual. Statistical Analysis: Analysis of variance (ANOVA), Student's t-test, the Pearson product-moment corre (PPMCC) and regression analysis were performed. Results: PPMCC value r = 0.347, 0.542 and 0.989 were obtained using light, polarized and phase contrast microscopy methods respectively. Conclusion: It was concluded that incremental lines of cementum were most clearly visible under a phase contrast microscope, followed by a polarized microscope, and then a light microscope when used for age estimation. PMID:26816462
A Bayesian approach to estimate skeletal age-at-death utilizing dental wear.
Prince, Debra A; Kimmerle, Erin H; Konigsberg, Lyle W
2008-05-01
In the forensic context, teeth are often recovered in mass disasters, armed conflicts, and mass graves associated with human rights violations. Therefore, for victim identification, techniques utilizing the dentition to estimate the first parameters of identity (e.g., age) can be critical. This analysis was undertaken to apply a Bayesian statistical method, transition analysis, based on the Gompertz-Makeham (GM) hazard model, to estimate individual ages-at-death for Balkan populations utilizing dental wear. Dental wear phases were scored following Smith's eight-phase ordinal scoring method and chart. To estimate age, probability density functions for the posterior distributions of age for each tooth phase are calculated. Transition analysis was utilized to generate a mean age-of-transition from one dental wear phase to the next. The age estimates are based on the calculated age distribution from the GM hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density region for each phase is calculated. By using a Bayesian statistical approach to estimate age, the population's age distribution is taken into account. Therefore, the age estimates are reliable for the Balkan populations, regardless of population or sex differences. The results showed that a vast amount of interpersonal variation in dental wear exists within the current sample and that this method may be most useful for classifying unknown individuals into broad age cohorts rather than small age ranges. PMID:18471201
Baudouin, M; Marengo, M; Pere, A; Culioli, J-M; Santoni, M-C; Marchand, B; Durieux, E D H
2016-02-01
Three methods of age estimation were compared for Dentex dentex. Based on sectioned otoliths, scales appeared to be relevant only up to 5 years and whole otoliths up to 12 years. The maximum estimated age was 36 years, which constitutes to date the oldest age reported. PMID:26563912
Striking effect of time variation in the estimation of groundwater age in the Wairarapa valley
NASA Astrophysics Data System (ADS)
Petrus, Karine; Toews, Michael; Daughney, Christopher; Cornaton, Fabien
2014-05-01
The Wairarapa Valley exhibits complex interactions between its rivers and shallow aquifers. With agriculture being an essential part of the region the risk of contamination and depletion of groundwater exists. In order to assist with water resource management in the region, we can do predictions with the help of numerical models. Among these predictions, the evaluation of groundwater age is critical for decision making. This project builds on work done by Greater Wellington Regional Council and will focus on the Wairarapa Valley. The aim of this study is to evaluate the age of the groundwater in the Wairarapa region. Investigations have already been done thanks to hydrochemistry. However radiometric age can be misleading in the sense that it does not consider the mixing process in the motion of groundwater particules. Therefore another approach can be considered .This latter is physic based by considering the age as a property that we transport through two main processes: advection at a macroscopic scale and diffusion at a microscopic scale. The determination of the distribution age by this approach has already been done for the Lake Rotorua but in the steady state case (cf Daughney). The unique contribution of the present study is to estimate the changes in groundwater age distribution through time within the region. Indeed transient simulations are needed to explicitly account for seasonally variable rainfall and pumping wells. This affects the simulated flow solution and then the simulated age solution. In order to solve numerically the transport of age distribution we have chosen to use the Time Marching Laplace Transform Galerkin technique which has been developed in a research code by Fabien Cornaton. The obtained results depict that temporal variations in groundwater age are present and have important implication for resource management
77 FR 4000 - Estimates of the Voting Age Population for 2011
Federal Register 2010, 2011, 2012, 2013, 2014
2012-01-26
... Office of the Secretary Estimates of the Voting Age Population for 2011 AGENCY: Office of the Secretary, Commerce. ACTION: General Notice Announcing Population Estimates. SUMMARY: This notice announces the voting age population estimates as of July 1, 2011, for each state and the District of Columbia. We...
78 FR 6289 - Estimates of the Voting Age Population for 2012
Federal Register 2010, 2011, 2012, 2013, 2014
2013-01-30
... Office of the Secretary Estimates of the Voting Age Population for 2012 AGENCY: Office of the Secretary, Commerce. ] ACTION: General notice announcing population estimates. SUMMARY: This notice announces the voting age population estimates as of July 1, 2012, for each state and the District of Columbia. We...
76 FR 37314 - Estimates of the Voting Age Population for 2010
Federal Register 2010, 2011, 2012, 2013, 2014
2011-06-27
... Office of the Secretary Estimates of the Voting Age Population for 2010 AGENCY: Office of the Secretary, Commerce. ACTION: General Notice Announcing Population Estimates. SUMMARY: This notice announces the voting age population estimates as of July 1, 2010, for each state and the District of Columbia. We...
75 FR 4343 - Estimates of the Voting Age Population for 2009
Federal Register 2010, 2011, 2012, 2013, 2014
2010-01-27
... Office of the Secretary Estimates of the Voting Age Population for 2009 AGENCY: Office of the Secretary, Commerce. ACTION: General Notice Announcing Population Estimates. SUMMARY: This notice announces the voting age population estimates as of July 1, 2009, for each state and the District of Columbia. We...
Tang, Nancy; Antoine, Daniel; Hillson, Simon
2014-11-01
The Bang and Ramm method uses root dentine translucency (RDT) length in sectioned or unsectioned teeth as a sole indicator of chronological age at death in adult human remains. The formulae have been tested on modern remains of known age and on modern and archaeological remains of unknown age. This is the first published study of the method on known-age archaeological specimens and tests whether RDT is a good indicator of chronological age in buried human remains. We applied the Bang and Ramm equations to two 18th and 19th century assemblages excavated from the crypt of Christ Church, Spitalfields, and the cemetery of All Hallows by the Tower. Translucency was defined by shining a light through the external unsectioned root surface and was measured from digital images of 583 and 83 nonmolar roots from 126 Spitalfields and 12 All Hallows individuals, respectively, aged 21-81 years. Average absolute difference between real age and estimated age was 10.7 years and 8.4 years for Spitalfields and All Hallows individuals, respectively, with 58% and 75% estimated within 10 years of known age, and 29% and 33% estimated within five years of known age. These estimations are comparable to results from other ageing methods applied to the Spitalfields collection. Ages from both populations were estimated largely to the middle ranges, with younger individuals overestimated and older individuals underestimated. This is a common occurrence when using inverse calibration, where age is treated as the dependent variable and the ageing feature as the independent variable. PMID:25043454
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.
Early-age concrete strength estimation based on piezoelectric sensor using artificial neural network
NASA Astrophysics Data System (ADS)
Kim, Junkyeong; Kim, Ju-Won; Park, Seunghee
2014-04-01
Recently, novel methods to estimate the strength of concrete have been reported based on numerous NDT methods. Especially, electro-mechanical impedance technique using piezoelectric sensors are studied to estimate the strength of concrete. However, the previous research works could not provide the general information about the early-age strength important to manage the quality of concrete and/or the construction process. In order to estimate the early-age strength of concrete, the electro-mechanical impedance method and the artificial neural network(ANN) is utilized in this study. The electro-mechanical impedance varies with the mechanical properties of host structures. Because the strength development is most influential factor among the change of mechanical properties at early-age of curing, it is possible to estimate the strength of concrete by analyzing the change of E/M impedance. The strength of concrete is a complex function of several factors like mix proportion, temperature, elasticity, etc. Because of this, it is hard to mathematically derive equations about strength of concrete. The ANN can provide the solution about early-age strength of concrete without mathematical equations. To verify the proposed approach, a series of experimental studies are conducted. The impedance signals are measured using embedded piezoelectric sensors during curing process and the resonant frequency of impedance is extracted as a strength feature. The strength of concrete is calculated by regression of strength development curve obtained by destructive test. Then ANN model is established by trained using experimental results. Finally the ANN model is verified using impedance data of other sensors.
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
NASA Astrophysics Data System (ADS)
Nakano, S.; Suzuki, K.; Kawamura, K.; Parrenin, F.; Higuchi, T.
2015-06-01
A technique for estimating the age-depth relationship in an ice core and evaluating its uncertainty is presented. The age-depth relationship is mainly determined by the accumulation of snow at the site of the ice core and the thinning process due to the horizontal stretching and vertical compression of ice layers. However, since neither the accumulation process nor the thinning process are fully understood, it is essential to incorporate observational information into a model that describes the accumulation and thinning processes. In the proposed technique, the age as a function of depth is estimated from age markers and δ18O data. The estimation is achieved using the particle Markov chain Monte Carlo (PMCMC) method, in which the sequential Monte Carlo (SMC) method is combined with the Markov chain Monte Carlo method. In this hybrid method, the posterior distributions for the parameters in the models for the accumulation and thinning processes are computed using the Metropolis method, in which the likelihood is obtained with the SMC method. Meanwhile, the posterior distribution for the age as a function of depth is obtained by collecting the samples generated by the SMC method with Metropolis iterations. The use of this PMCMC method enables us to estimate the age-depth relationship without assuming either linearity or Gaussianity. The performance of the proposed technique is demonstrated by applying it to ice core data from Dome Fuji in Antarctica.
Seger, G D S; Duarte, L D S; Debastiani, V J; Kindel, A; Jarenkow, J A
2013-09-01
Understanding how species traits evolved over time is the central question to comprehend assembly rules that govern the phylogenetic structure of communities. The measurement of phylogenetic signal (PS) in ecologically relevant traits is a first step to understand phylogenetically structured community patterns. The different methods available to estimate PS make it difficult to choose which is most appropriate. Furthermore, alternative phylogenetic tree hypotheses, node resolution and clade age estimates might influence PS measurements. In this study, we evaluated to what extent these parameters affect different methods of PS analysis, and discuss advantages and disadvantages when selecting which method to use. We measured fruit/seed traits and flowering/fruiting phenology of endozoochoric species occurring in Southern Brazilian Araucaria forests and evaluated their PS using Mantel regressions, phylogenetic eigenvector regressions (PVR) and K statistic. Mantel regressions always gave less significant results compared to PVR and K statistic in all combinations of phylogenetic trees constructed. Moreover, a better phylogenetic resolution affected PS, independently of the method used to estimate it. Morphological seed traits tended to show higher PS than diaspores traits, while PS in flowering/fruiting phenology depended mostly on the method used to estimate it. This study demonstrates that different PS estimates are obtained depending on the chosen method and the phylogenetic tree resolution. This finding has implications for inferences on phylogenetic niche conservatism or ecological processes determining phylogenetic community structure. PMID:23368095
Age Estimation of African Lions Panthera leo by Ratio of Tooth Areas.
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. PMID:27089506
Age Estimation of African Lions Panthera leo by Ratio of Tooth Areas
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
RESEARCH PAPER: Old stellar population synthesis: new age and mass estimates for Mayall II = G1
NASA Astrophysics Data System (ADS)
Ma, Jun; de Grijs, Richard; Fan, Zhou; Rey, Soo-Chang; Wu, Zhen-Yu; Zhou, Xu; Wu, Jiang-Hua; Jiang, Zhao-Ji; Chen, Jian-Sheng; Lee, Kyungsook; Sohn, Sangmo Tony
2009-06-01
Mayall II = G1 is one of the most luminous globular clusters (GCs) in M31. Here, we determine its age and mass by comparing multicolor photometry with theoretical stellar population synthesis models. Based on far- and near-ultraviolet GALEX photometry, broad-band UBVRI, and infrared JHKS 2MASS data, we construct the most extensive spectral energy distribution of G1 to date, spanning the wavelength range from 1538 to 20 000 Å. A quantitative comparison with a variety of simple stellar population (SSP) models yields a mean age which is consistent with G1 being among the oldest building blocks of M31 and having formed within ~1.7 Gyr after the Big Bang. Irrespective of the SSP model or stellar initial mass function adopted, the resulting mass estimates (of order 107 Modot) indicate that G1 is one of the most massive GCs in the Local Group. However, we speculate that the cluster's exceptionally high mass suggests that it may not be a genuine GC. Our results also suggest that G1 may contain, on average, (1.65±0.63) × 102 Lodot far-ultraviolet-bright, hot, extreme horizontal-branch stars, depending on the adopted SSP model. In addition, we demonstrate that extensive multi-passband photometry coupled with SSP analysis enables one to obtain age estimates for old SSPs that have similar accuracies as those from integrated spectroscopy or resolved stellar photometry, provided that some of the free parameters can be constrained independently.
Dental age estimation in a Brazilian adult population using Cameriere's method.
Azevedo, Alana de Cássia Silva; Alves, Nathalia Zanini; Michel-Crosato, Edgard; Rocha, Marcos; Cameriere, Roberto; Biazevic, Maria Gabriela Haye
2015-01-01
The objectives of this study were to develop a specific formula to estimate age in a Brazilian adult population and to compare the original formula from Cameriere to this Brazilian formula. The sample comprised 1,772 periapical radiographs from 443 subjects (219 men, 224 women) that were organized into 12 groups according to sex (men or women) and age (20-29, 30-39, 40-49, 50-59, 60-69, and 70 years and older). The films were analyzed using the criteria described by Cameriere et al. (2004) and Adobe Photoshop®. We obtained a mean error of 8.56 (SD = 5.80) years for tooth 13, 7.99 (SD = 5.78) years for tooth 23, 8.38 (SD = 6.26) years for tooth 33, and 8.20 (SD = 6.54) years for tooth 43. When teeth were combined in the analysis, we observed lower mean errors. The Brazilian formula developed from this sample group was more accurate than Cameriere's formula. However, other factors must be considered to improve age estimates in adults. PMID:25590504
Thermoluminescence and new 14C age estimates for late quaternary loesses in southwestern Nebraska
Maat, P.B.; Johnson, W.C.
1996-01-01
Loess of late Quaternary age mantles most of Nebraska south of the Platte River Valley. At least five late Quaternary loesses are recognized: from oldest to youngest, one or more undifferentiated pre-lllinoian loesses, the Loveland Loess, the Gilman Canyon Loess, which exhibits a well developed soil and rests unconformably on the Sangamon soil, the Peoria Loess capped by the Brady soil, and the Bignell Loess, which is distributed discontinuously. Previous research shows that the Loveland Loess is Illinoian. the Gilman Canyon Loess and Peoria Loess are Wisconsin, and the Bignell Loess is Holocene. We present here the first thermoluminescence (TL) age estimates and new C ages for these late Quaternary loesses at two key sections in southwestern Nebraska, the Eustis ash pit and the Bignell Hill road cut. TL age estimates from all samples collected from Eustis ash pit and Bignell Hill were internally consistent. TL and C age estimates from these two sections generally agree and support previous age determinations. The TL age estimate on Loveland Loess indicates deposition at 163 ka. TL and radiocarbon age estimates indicate that Oilman Canyon Loess, believed to be deposited during the Farmdale interstade, first began to accumulate at about 40 ka: the lower part of the Gilman Canyon Loess is 36 ka at Eustis and the middle of the unit is 30 ka at Bignell Hill. The lower and upper parts of the Peoria Loess give age estimates of 24 ka and 17 ka, respectively. TL age estimates for deposition of the Bignell Loess are 9 ka near the base, in agreement with radiocarbon age estimates, and 6 ka immediately below the modern soil, substantiating its Holocene age. Comparisons of TL age estimates with ??18O and insolation curves which show loess deposition during interglacial and interstadial as well as glacial periods, indicate that loess deposition on the Great Plains can occur under a variety of climatic conditions.
NASA Astrophysics Data System (ADS)
Nakano, Shin'ya; Suzuki, Kazue; Kawamura, Kenji; Parrenin, Frédéric; Higuchi, Tomoyuki
2016-02-01
A technique for estimating the age-depth relationship in an ice core and evaluating its uncertainty is presented. The age-depth relationship is determined by the accumulation of snow at the site of the ice core and the thinning process as a result of the deformation of ice layers. However, since neither the accumulation rate nor the thinning process is fully known, it is essential to incorporate observational information into a model that describes the accumulation and thinning processes. In the proposed technique, the age as a function of depth is estimated by making use of age markers and δ18O data. The age markers provide reliable age information at several depths. The data of δ18O are used as a proxy of the temperature for estimating the accumulation rate. The estimation is achieved using the particle Markov chain Monte Carlo (PMCMC) method, which is a combination of the sequential Monte Carlo (SMC) method and the Markov chain Monte Carlo method. In this hybrid method, the posterior distributions for the parameters in the models for the accumulation and thinning process are computed using the Metropolis method, in which the likelihood is obtained with the SMC method, and the posterior distribution for the age as a function of depth is obtained by collecting the samples generated by the SMC method with Metropolis iterations. The use of this PMCMC method enables us to estimate the age-depth relationship without assuming either linearity or Gaussianity. The performance of the proposed technique is demonstrated by applying it to ice core data from Dome Fuji in Antarctica.
Re-Evaluating Neonatal-Age Models for Ungulates: Does Model Choice Affect Survival Estimates?
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
Re-evaluating neonatal-age models for ungulates: Does model choice affect survival estimates?
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
Slice, Dennis E; Algee-Hewitt, Bridget F B
2015-07-01
The pubic symphysis is widely used in age estimation for the adult skeleton. Standard practice requires the visual comparison of surface morphology against criteria representing predefined phases and the estimation of case-specific age from an age range associated with the chosen phase. Known problems of method and observer error necessitate alternative tools to quantify age-related change in pubic morphology. This paper presents an objective, fully quantitative method for estimating age-at-death from the skeleton, which exploits a variance-based score of surface complexity computed from vertices obtained from a scanner sampling the pubic symphysis. For laser scans from 41 modern American male skeletons, this method produces results that are significantly associated with known age-at-death (RMSE = 17.15 years). Chronological age is predicted, therefore, equally well, if not, better, with this robust, objective, and fully quantitative method than with prevailing phase-aging systems. This method contributes to forensic casework by responding to medico-legal expectations for evidence standards. PMID:25929827
NASA Astrophysics Data System (ADS)
Lemarchand, Guillermo A.
2004-06-01
Based on the study of several long-term societal indicators we estimate the phase transition between the ``Technological Adolescent Age'' (TAA) and the ``Technological Mature Age'' (TMA). Assuming the ``Principle of Mediocrity'' and using the Drake Equation we estimate a lower threshold for the number of technological civilizations in the galaxy.
The lateral clavicular epiphysis: fusion timing and age estimation.
Langley, Natalie R
2016-03-01
This study utilizes a forensic autopsy sample of twentieth century American Whites (the McCormick Clavicle Collection) to describe the morphology, variation, and fusion timing of the lateral clavicle epiphysis. Clavicles from individuals between 11 and 25 years at the time of death were used to document fusion of the lateral epiphysis (n= 133, 38 females and 95 males). The lateral epiphysis was scored as unfused, fusing, or fused. A linear weighted kappa indicates that this scoring method is highly replicable with almost perfect inter-rater agreement (kappa = 0.849), according to a widely used standard for assessing kappa values. Transition analysis, or probit regression, was employed to quantify fusion timing of the lateral epiphysis. The transition from "unfused" to "fusing" is most likely to occur at 16.5 years in females and 17.5 years in males. The transition from "fusing" to "fused" occurs at age 21 in females and age 20 in males. The earliest age at which fusion began was 15 years (n = 1), but the majority began fusing between 17 and 20 years. Most individuals (98.5 % of the sample) aged >24 years had fused lateral epiphyses. The epiphysis assumes one of two forms: (1) a separate bony flake fusing to the diaphysis or (2) a mound of bone glazing/smoothing over the diaphyseal surface. As socioeconomic status has been cited as the most influential variable on skeletal maturation rates, the fusion ages offered here should not be applied to populations with a socioeconomic status different from the greater US population. PMID:26253853
Grimes, Joshua; 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 the 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 (D90
NASA Technical Reports Server (NTRS)
Peterson, Harold; Koshak, William J.
2009-01-01
An algorithm has been developed to estimate the altitude distribution of one-meter lightning channel segments. The algorithm is required as part of a broader objective that involves improving the lightning NOx emission inventories of both regional air quality and global chemistry/climate models. The algorithm was tested and applied to VHF signals detected by the North Alabama Lightning Mapping Array (NALMA). The accuracy of the algorithm was characterized by comparing algorithm output to the plots of individual discharges whose lengths were computed by hand; VHF source amplitude thresholding and smoothing were applied to optimize results. Several thousands of lightning flashes within 120 km of the NALMA network centroid were gathered from all four seasons, and were analyzed by the algorithm. The mean, standard deviation, and median statistics were obtained for all the flashes, the ground flashes, and the cloud flashes. One-meter channel segment altitude distributions were also obtained for the different seasons.
NASA Astrophysics Data System (ADS)
Quirino, V. F.; Wynne, R. H.; Burkhart, H.; Thomas, V. A.
2012-12-01
The objective of this study was to evaluate the utility of small-footprint discrete return LiDAR for determining loblolly pine stand age. The study area was in the Appomattox-Buckingham State Forest, Virginia, USA. LiDAR data were acquired in 2008 using an Optech ALTM 3100. A stratified random sampling approach was used to select over 200 circular plots (15 m radius) with ages (the dependent variable) varying from 5 to 71 years old. LiDAR-derived independent variables were obtained using metrics computed from normalized point densities, heights (above ground) and intensities. The three best models have only one to two variables, as follows: 100th percentile of height alone (adjusted R2 = 88.3%, RMSE = 1.2 years), 100th percentile of height along with the variance of intensity (adjusted R2 = 90.8%, RMSE = 1.17 years), and the 99.5th percentile along with the density of points between the 20th and 40th percentiles (adjusted R2 = 90.6%, RMSE = 1.17 years). These results show that small-footprint, discrete return LiDAR can be used to estimate plot level age of loblolly pine stands - and may, by inference, be used to establish indices of site quality if age is known.
Vabbalareddy, Raja Sekhar; V Vanga, Narasimha Rao
2014-01-01
ABSTRACT% Dental age is important for treatment planning in the specialities of pedodontics and orthodontics. Although, Demirjian's method was considered standard for dental age estimation, it may not be reliable for all population. Aim: The goal of the study was to evaluate the reliability of Demir-jian's, Haavikko's and Willems method of dental age estimation methods in Visakhapatnam (Andhra Pradesh, India) children. Study design: One hundred and two children of 6 to 14 years old who underwent panaromic digital radiography for routine diagnostic purposes were included. Dental age was calculated using Demirjian's, Haavikko's and Willems methods and compared with chronologic age for each patient. Results: Dental age showed a significant overestimation by Demirjian's method with a mean difference of 0.55 year and underestimation by Haavikko's and Willems methods with a mean difference of 1.95 and 0.20 year respectively when compared with chronologic age. The mean difference between dental age and chronologic age was not significant in Willems method which shows a close relation between dental and chronologic ages. Conclusion: The dental age estimation by Willems method is found to be more accurate than Demirjian's and Haavikko's methods in Visakhapatnam children. How to cite this article: Patnana AK, Vabbalareddy RS, Vanga NRV. Evaluating the Reliability of Three Different Dental Age Estimation Methods in Visakhapatnam Children. Int J Clin Pediatr Dent 2014;7(3):186-191. PMID:25709299
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
NASA Astrophysics Data System (ADS)
Strigaro, Daniele; Moretti, Massimiliano; Mattavelli, Matteo; Frigerio, Ivan; Amicis, Mattia De; Maggi, Valter
2016-09-01
The aim of this work is to integrate the Minimal Glacier Model in a Geographic Information System Python module in order to obtain spatial simulations of glacier retreat and to assess the future scenarios with a spatial representation. The Minimal Glacier Models are a simple yet effective way of estimating glacier response to climate fluctuations. This module can be useful for the scientific and glaciological community in order to evaluate glacier behavior, driven by climate forcing. The module, called r.glacio.model, is developed in a GRASS GIS (GRASS Development Team, 2016) environment using Python programming language combined with different libraries as GDAL, OGR, CSV, math, etc. The module is applied and validated on the Rutor glacier, a glacier in the south-western region of the Italian Alps. This glacier is very large in size and features rather regular and lively dynamics. The simulation is calibrated by reconstructing the 3-dimensional dynamics flow line and analyzing the difference between the simulated flow line length variations and the observed glacier fronts coming from ortophotos and DEMs. These simulations are driven by the past mass balance record. Afterwards, the future assessment is estimated by using climatic drivers provided by a set of General Circulation Models participating in the Climate Model Inter-comparison Project 5 effort. The approach devised in r.glacio.model can be applied to most alpine glaciers to obtain a first-order spatial representation of glacier behavior under climate change.
Lysyk, T J; Steelman, C D
2004-07-01
Reanalysis of counts of horn fly, Hematobia irritans (L.), obtained from a variety of cattle herds indicated that aggregation of the flies within herds decreased as mean fly density increased. Aggregation was also related to the proportion of fly-resistant and fly-susceptible cattle in a herd. Herds were grouped according to their degree of horn fly aggregation. Low aggregation herds included larger framed Angus, Horned Hereford, Polled Hereford, and Red Poll breeds. Moderate aggregation occurred with Brahman, Charolais, small-framed Angus, mixed cows, and Hereford x Charolais cross. High aggregation occurred with Chianina and mixed herds. Relationships between the sample means and variances varied among aggregation groups. A resampling approach was used to determine the influence of random sampling of a herd on the proportion of horn fly population estimates within fixed percentages of the true mean. The proportion of sample means within +/- 5, 10, 15, and 20% of the true means varied with the proportion of the herd sampled, the mean and variance of fly density, and herd size. Recommendations for obtaining sample size to estimate fly density within a fixed percentage of the true mean are given. PMID:15311450
Ipiña, Emiliano Pérez; Dawson, Silvina Ponce
2014-01-01
The interior of cells is a highly fluctuating environment. Fluctuations set limits to the accuracy with which endogenous processes can occur. The physical principles that rule these limits also affect the experimental quantification of biophysical parameters in situ. The characterization of fluctuations, on the other hand, provides a way to quantify biophysical parameters. But as with any random process, enough data has to be collected to achieve a reliable quantitative description. In this article we study the accuracy with which intracellular concentrations can be estimated using fluorescence correlation spectroscopy. We show that, when the observed molecules interact with immobile species or experience other restrictions to their movement, the hypotheses commonly used to estimate concentrations are no longer valid. The interactions with immobile sites reduce the fluorescence variance by a finite amount. The time that is necessary to obtain an accurate concentration estimate, on the other hand, is hundreds of times larger than the slowest correlation time and is much larger when the sites move slowly than when they are immobile. Our analysis is applicable to other related techniques and it also sheds light on the way in which effector concentrations are read by target molecules in cells. PMID:25468346
Pérez Ipiña, Emiliano; Ponce Dawson, Silvina
2014-12-01
The interior of cells is a highly fluctuating environment. Fluctuations set limits to the accuracy with which endogenous processes can occur. The physical principles that rule these limits also affect the experimental quantification of biophysical parameters in situ. The characterization of fluctuations, on the other hand, provides a way to quantify biophysical parameters. But as with any random process, enough data has to be collected to achieve a reliable quantitative description. In this article we study the accuracy with which intracellular concentrations can be estimated using fluorescence correlation spectroscopy. We show that, when the observed molecules interact with immobile species or experience other restrictions to their movement, the hypotheses commonly used to estimate concentrations are no longer valid. The interactions with immobile sites reduce the fluorescence variance by a finite amount. The time that is necessary to obtain an accurate concentration estimate, on the other hand, is hundreds of times larger than the slowest correlation time and is much larger when the sites move slowly than when they are immobile. Our analysis is applicable to other related techniques and it also sheds light on the way in which effector concentrations are read by target molecules in cells. PMID:25468346
New Method of Age Estimation from Maxillary Sutures Closure in a Thai Population.
Sinthubua, A; Theera-Umpon, N; Auephanwiriyakul, S; Ruengdit, S; Das, S; Mahakkanukrauh, P
2016-01-01
Age estimation is one of the major components of forensic identification. Cranial suture closure has long been used as indicator for age estimation. Maxillary sutures have been less studied for estimation of age at death because they vary in their timing of closure with age. The purpose of this study was to estimate age by examining 190 Thai skulls with age ranging between 15-93 years from Forensic Osteology Research Center, Faculty of Medicine, and Chiang Mai University. Four parts of maxillary suture (incisive, anterior, transverse, and posterior sutures) were investigated the suture obliteration of each suture by computerizing from photograph. The suture were measured by pixel counting.The prediction model which based on the support vector machine (SVM) for regression or support vector regression (SVR) was utilized for data analysis. The results showed high correlation (R2 = 0.9086) between the predicted age and actual age. Plot between actual age group and predicted age in seven groups also revealed high correlation (R2 = 0.9434). These can be implied that we are able to use this SVR model to predict age at death using maxillary suture information.The interesting issue is to further apply this model in more cases to ensure the generalization of the finding. This study is the first attempt to estimate age at death using a new method based on novel analysis which considers a characteristic of relationship between maxillary suture closures with age that are not in linear form. The present study may contribute as a basis knowledge and method for further study of age estimation in archaeological and forensic anthropological contexts, especially when only skull or base of skull are found. PMID:27212570
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. PMID:26934764
Accuracy and precision of estimating age of gray wolves by tooth wear
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.
Postnatal growth and age estimation in Scotophilus kuhlii.
Chen, Shiang-Fan; Huang, Shang-Shang; Lu, Dau-Jye; Shen, Tsung-Jen
2016-01-01
Adequate postnatal growth is important for young bats to develop skilled sensory and locomotor abilities, which are highly associated with their survival once independent. This study investigated the postnatal growth and development of Scotophilus kuhlii in captivity. An empirical growth curve was established, and the postnatal growth rate was quantified to derive an age-predictive equation. By further controlling the fostering conditions of twins, the differences in the development patterns between pups that received maternal care or were hand-reared were analyzed to determine whether the latter developed in the same manner as their maternally reared counterparts. Our results indicate that both forearm length and body mass increased rapidly and linearly during the first 4 weeks, after which the growth rate gradually decreased to reach a stable level. The first flight occurred at an average age of 39 days with a mean forearm length and body mass of 92.07% and 70.52% of maternal size, respectively. The developmental pattern of hand-reared pups, although similar to that of their maternally reared twin siblings, displayed a slightly faster growth rate in the 4th and 5th weeks. The heavier body mass of hand-reared pups during the pre-fledging period may cause higher wing loading, potentially influencing the flight performance and survival of the bats once independent. PMID:26600428
Babburi, Suresh; Nelakurthi, Hasini; Aparna, V; Soujanya, P; Kotti, Ajay Benarji; Ganipineni, Kiranmai
2015-01-01
Background: Age estimation is an important factor in establishing the identity of a person. Among various techniques, dental age estimation is helpful in estimating the age in children above 16 years of age. Determination of age using developmental stages of teeth is more useful than using tooth eruption. Materials and Methods: A total of 550 orthopantomographs of 248 males and 302 females aged between 15 and 22 years were taken and evaluated by Demirjian’s tooth mineralization stages. Statistical assessment was done using logistic regression analysis. Results: Complete apical closure of third molars was observed at the age of 20.4 years in 50% of males. Gender is also thought to influence mineralization and males showed early apical closure than females. Mean value testing is also done but showed influence of high and lower end age groups on age estimation. Conclusion: Finally, we conclude that, though the exact age of a person cannot be determined, the Demirjian’s stage at which 18 years of age is attained can be found out. PMID:26028903
The utility of near infrared spectroscopy for age estimation of deepwater sharks
NASA Astrophysics Data System (ADS)
Rigby, Cassandra L.; Wedding, Brett B.; Grauf, Steve; Simpfendorfer, Colin A.
2014-12-01
Reliable age information is vital for effective fisheries management, yet age determinations are absent for many deepwater sharks as they cannot be aged using traditional methods of growth bands counts. An alternative approach to ageing using near infrared spectroscopy (NIRS) was investigated using dorsal fin spines, vertebrae and fin clips of three species of deepwater sharks. Ages were successfully estimated for the two dogfish, Squalus megalops and Squalus montalbani, and NIRS spectra were correlated with body size in the catshark, Asymbolus pallidus. Correlations between estimated-ages of the dogfish dorsal fin spines and their NIRS spectra were good, with S. megalops R2=0.82 and S. montalbani R2=0.73. NIRS spectra from S. megalops vertebrae and fin clips that have no visible growth bands were correlated with estimated-ages, with R2=0.89 and 0.76, respectively. NIRS has the capacity to non-lethally estimate ages from fin spines and fin clips, and thus could significantly reduce the numbers of sharks that need to be lethally sampled for ageing studies. The detection of ageing materials by NIRS in poorly calcified deepwater shark vertebrae could potentially enable ageing of this group of sharks that are vulnerable to exploitation.
Accuracy of Four Dental Age Estimation Methods in Southern Indian Children
Sanghvi, Praveen; Perumalla, Kiran Kumar; Srinivasaraju, D.; Srinivas, Jami; Kalyan, U. Siva; Rasool, SK. Md. Iftekhar
2015-01-01
Introduction: For various forensic investigations of both living and dead individuals, the knowledge of the actual age or date of birth of the subject is of utmost importance. In recent years, age estimation has gained importance 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. Developing teeth are used to assess maturity and estimate age in number of disciplines; however the accuracy of different methods has not been assessed systematically. The aim of this study was to determine the accuracy of four dental age estimation methods. Materials and Methods: Digital Orthopantomographs (OPGS) of South Indian children between the ages of 6 and 16 y who visited the department of Department of Oral medicine and Radiology of GITAM Dental College, Visakhapatnam, Andhra Pradesh, India with similar ethnic origin were assessed. Dental age was calculated using Demirjian, Willems, Nolla, and adopted Haavikko methods and the difference between estimated dental age and chronological age were compared with paired t-test and Wilcoxon signed rank test. Results: An overestimation of the dental age was observed by using Demirjian and Nolla methods (0.1±1.63, 0.47±0.83 years in total sample respectively) and an underestimation of dental age was observed by using Willems and Haavikko methods (-0.4±1.53, -2.9±1.41 years respectively in total sample). Conclusion: Nolla’s method was more accurate in estimating dental age compared to other methods. Moreover, all the four methods were found to be reliable in estimating age of individuals of unknown chronological age in South Indian children. PMID:25738008
Whiteman, K.W.; Travnichek, V.H.; Wildhaber, M.L.; DeLonay, A.; Papoulias, D.; Tillett, D.
2004-01-01
Numerous studies have examined the age and growth of shovelnose sturgeon Scaphirhynchus platorynchus, but only one study attempted to validate age estimation techniques. Therefore, our objective was to use marginal increment analysis to validate annulus formation in pectoral fin rays of shovelnose sturgeon collected from the Missouri River. We also compared the precision of age estimates between two different readers. Marginal increment distance indicated that for most of the populations an opaque band was laid down in pectoral fin rays during the summer. However, opaque bands were formed throughout the year in some individuals, which could be problematic when using fin rays for age estimation. The agreement of age estimates by two readers for shovelnose sturgeon was only 18%, and differences in ages between the two readers increased for older fish. The presence of split annuli, false annuli, spawning bands, imbedded rays, and deteriorating sections made individual growth rings difficult to separate. Our findings verified that opaque bands are formed annually during the summer in the pectoral fin rays of most shovelnose sturgeon, but some individuals form opaque bands during other times. Pectoral fin rays will probably continue to be the most practical method of age estimation in shovelnose sturgeon, but ages estimated by this method should be used with caution.
Estimating survival rates with time series of standing age-structure data
Udevitz, Mark S.; Gogan, Peter J.
2014-01-01
It has long been recognized that age-structure data contain useful information for assessing the status and dynamics of wildlife populations. For example, age-specific survival rates can be estimated with just a single sample from the age distribution of a stable, stationary population. For a population that is not stable, age-specific survival rates can be estimated using techniques such as inverse methods that combine time series of age-structure data with other demographic data. However, estimation of survival rates using these methods typically requires numerical optimization, a relatively long time series of data, and smoothing or other constraints to provide useful estimates. We developed general models for possibly unstable populations that combine time series of age-structure data with other demographic data to provide explicit maximum likelihood estimators of age-specific survival rates with as few as two years of data. As an example, we applied these methods to estimate survival rates for female bison (Bison bison) in Yellowstone National Park, USA. This approach provides a simple tool for monitoring survival rates based on age-structure data.
Bias Correction of MODIS AOD using DragonNET to obtain improved estimation of PM2.5
NASA Astrophysics Data System (ADS)
Gross, B.; Malakar, N. K.; Atia, A.; Moshary, F.; Ahmed, S. A.; Oo, M. M.
2014-12-01
MODIS AOD retreivals using the Dark Target algorithm is strongly affected by the underlying surface reflection properties. In particular, the operational algorithms make use of surface parameterizations trained on global datasets and therefore do not account properly for urban surface differences. This parameterization continues to show an underestimation of the surface reflection which results in a general over-biasing in AOD retrievals. Recent results using the Dragon-Network datasets as well as high resolution retrievals in the NYC area illustrate that this is even more significant at the newest C006 3 km retrievals. In the past, we used AERONET observation in the City College to obtain bias-corrected AOD, but the homogeneity assumptions using only one site for the region is clearly an issue. On the other hand, DragonNET observations provide ample opportunities to obtain better tuning the surface corrections while also providing better statistical validation. In this study we present a neural network method to obtain bias correction of the MODIS AOD using multiple factors including surface reflectivity at 2130nm, sun-view geometrical factors and land-class information. These corrected AOD's are then used together with additional WRF meteorological factors to improve estimates of PM2.5. Efforts to explore the portability to other urban areas will be discussed. In addition, annual surface ratio maps will be developed illustrating that among the land classes, the urban pixels constitute the largest deviations from the operational model.
Image analysis of pubic bone for age estimation in a computed tomography sample.
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. PMID:24986514
An evaluation of agreement between pectoral spines and otoliths for estimating ages of catfishes
Olive, J.A.; Schramm, Harold, Jr.; 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.
Bednarek, Jarosław
2006-01-01
Chronological age assessment of young persons featuring in pornographic pictures and videos is crucial to prove a violation of law. The paper discusses possibilities of and difficulties inherent in age estimation in cases of production and distribution of child pornography. The presented problems were divided into technical and individual development-associated issues. Technical difficulties included lack of a reference system for biological features reconstruction, poor quality and resolution of pictures or movies, pictures retouching and photomontage. The author stressed that biological hindrances in age assessment were the consequences of interpersonal variation of developmental patterns, namely overlapping of ranges typical for feature values at particular ages and biological variations between different human populations. The described problems can render age estimation impossible or far from precise. Developing more accurate methods of estimating age from pictures and videos requires the collaboration of specialists in the field of auxology, anthropology, pediatrics, as well as experts in photography and video techniques. PMID:17131758
Estimating age of sea otters with cementum layers in the first premolar
Bodkin, J.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.
Strategic Decision-Making Learning from Label Distributions: An Approach for Facial Age Estimation
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
Zaher, Jaklin Fekri; Fawzy, Irene Atef; Habib, Sahar Refaat; Ali, Magdy Mohamed
2011-02-01
Age estimation from dental radiographs is a non-destructive, simple method to obtain information. The aim of this study was to determine the reliability of age estimation from Egyptians' incisors radiographs. 144 periapical radiographs of maxillary (central & lateral) incisors (both sexes) aged 12-60 were used. Digital camera was used to image the radiographs. Images were computed and pulp/tooth area ratios were determined by AutoCAD Program. Data were subjected to correlation and regression analysis which showed statistically significant correlation (r = 0.23 &P = 0.006 for maxillary central incisors and r = -0.2 &P = 0.05 for maxillary lateral incisors) between age and pulp tooth area ratio. Linear regression equations were determined separately for both central and lateral incisors along with the corresponding Standard Error of Estimate, which ranged from 1.2 to 5.08 years. Consequently, it was concluded that pulp/tooth area ratios of incisors are reliable for estimation of age among Egyptians in forensic work. PMID:21315299
Age estimation of an Indian population by using the Kim's scoring system of occlusal tooth wear
Telang, Lahari A.; Patil, Karthikeya; Mahima, V. G.
2014-01-01
Context: Age is one of the prime factors employed to establish the identity of an individual and the use of teeth for this purpose has been considered reliable. Tooth wear is widely accepted as a physiological consequence of aging and evaluation of tooth wear can be a simple and convenient tool to estimate age in adults. Aims: The present study was conducted to record the degree of tooth wear among Indian adults and to estimate their ages from the degree of tooth wear based on Kim's scoring system. Materials and Methods: Dental stone casts of 120 participants were used to assess the degree of occlusal tooth wear based on the criteria given by Kim et al. Statistical Analysis Used: The age of all subjects was estimated based on these scores using multiple regression analysis function. Results: The degree of tooth wear showed a significant positive correlation with age in each and every examined tooth of both males and females. The predicted age was within ± 5 years of actual age in 70% of males and 68.3% females, and within ± 3 years of actual age in 50% of males and 50.1% of females. Conclusions: Kim's scoring system has proven to be a useful tool in estimation of age using occlusal wear in an Indian population with a high level of accuracy in adults. PMID:24695780
Analysis of age-at-death estimation through the use of pubic symphyseal data.
Kimmerle, Erin H; Konigsberg, Lyle W; Jantz, Richard L; Baraybar, Jose Pablo
2008-05-01
The question of whether age parameters derived from an American population will reliably estimate age-at-death for East European skeletal populations is important since the ability to accurately estimate an individual's age-at-death hinges on what standard is used. A reference sample of identified individuals with known ages-at-death from the regions of the Former Yugoslavia (n = 861) is used to determine the age structure of victims and serves as the prior in the Bayesian analysis. Pubic symphyseal data in the manners of Todd (Am J Phys Anthropol, 3 [1920], 285; Am J Phys Anthropol, 4 [1921], 1) and Suchey-Brooks (Am J Phys Anthropol, 80 [1986], 167) were collected for n = 296 Balkan males and females and for n = 2078 American males and females. An analysis of deviance is calculated using an improvement chi-square to test for population variation in the aging processes of American and East European populations using proportional odds probit regression. When males and females are treated separately, there is a significant association among females and the population (df = 1, chi-square likelihood ratio = 15.071, p = 0.001). New age estimates for Balkan populations are provided and are based on the calculated age distribution from the Gompertz-Makeham hazard analysis and the ages-of-transition. To estimate the age-at-death for an individual, the highest posterior density regions for each symphyseal phase are provided. PMID:18471198
An HST/WFPC2 survey of bright young clusters in M 31. IV. Age and mass estimates
NASA Astrophysics Data System (ADS)
Perina, S.; Cohen, J. G.; Barmby, P.; Beasley, M. A.; Bellazzini, M.; Brodie, J. P.; Federici, L.; Fusi Pecci, F.; Galleti, S.; Hodge, P. W.; Huchra, J. P.; Kissler-Patig, M.; Puzia, T. H.; Strader, J.
2010-02-01
Aims: We present the main results of an imaging survey of possible young massive clusters (YMC) in M 31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST), with the aim of estimating their age and their mass. We obtained shallow (to B ˜ 25) photometry of individual stars in 19 clusters (of the 20 targets of the survey). We present the images and color magnitude diagrams (CMDs) of all of our targets. Methods: Point spread function fitting photometry of individual stars was obtained for all the WFPC2 images of the target clusters, and the completeness of the final samples was estimated using extensive sets of artificial stars experiments. The reddening, age, and metallicity of the clusters were estimated by comparing the observed CMDs and luminosity functions (LFs) with theoretical models. Stellar masses were estimated by comparison with theoretical models in the log(Age) vs. absolute integrated magnitude plane, using ages estimated from our CMDs and integrated J, H, K magnitudes from 2MASS-6X. Results: Nineteen of the twenty surveyed candidates were confirmed to be real star clusters, while one turned out to be a bright star. Three of the clusters were found not to be good YMC candidates from newly available integrated spectroscopy and were in fact found to be old from their CMD. Of the remaining sixteen clusters, fourteen have ages between 25 Myr and 280 Myr, two have older ages than 500 Myr (lower limits). By including ten other YMC with HST photometry from the literature, we assembled a sample of 25 clusters younger than 1 Gyr, with mass ranging from 0.6× 10^4 Msun to 6× 10^4 Msun, with an average of ˜3× 10^4 Msun. Our estimates of ages and masses well agree with recent independent studies based on integrated spectra. Conclusions: The clusters considered here are confirmed to have masses significantly higher than Galactic open clusters (OC) in the same age range. Our analysis indicates that YMCs are relatively
Age Estimation Based on Children's Voice: A Fuzzy-Based Decision Fusion Strategy
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
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. PMID:26698389
Egg flotation estimates nest age for Pacific and Red-throated Loons
Rizzolo, D.J.; Schmutz, J.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.
Maggio, Ariane; Flavel, Ambika; Hart, Rob; Franklin, Daniel
2016-06-01
Various age estimation techniques have been utilised in Australia to evaluate the age of individuals who do not have documentation to determine legal majority/culpability. These age estimation techniques rely on the assessment of skeletal development as visualised in radiographs, CT scans, MRI or ultrasound modalities, and subsequent comparison to reference standards. These standards are not always population specific and are thus known to be less accurate when applied outside of the original reference sample, leading to potential ethical implications. Therefore, the present study aims to: (i) explore the variation in developmental trajectories between the established Tanner-Whitehouse (TW) age estimation standards and a Western Australian population; and (ii) develop specific hand-wrist age estimation standards for the latter population. The present study examines digital anterior-posterior hand-wrist radiographs of 360 individuals 0 to 24.9 years of age, equally represented by sex. Each radiograph was assessed using the RUS, Carpal and 20-bone methods of Tanner et al. The standard error of the estimate (SEE) was calculated for each method (range: ♀ SEE ±0.4-11.5 years; ♂ SEE ±0.9-10.1 years). The most accurate method was TW3 RUS for females and the TW2 Carpal system for males. The 50th centile skeletal maturity scores for each year age group were plotted against average chronological age to produce polynomial regression standards with a demonstrated accuracy of (♀ SEE ±0.09-3.46 years; ♂ SEE ±0.02-3.42 years) for females and males, respectively. The standards presented here can be used in future forensic investigations that require age estimation of hand-wrist bones in a Western Australian population, however, they are not appropriate for establishing age of majority (18 years), as skeletal maturity was attained on average earlier than 15 years of age in both sexes for all three systems examined. PMID:27080619
A revised burial dose estimation procedure for optical dating of youngand modern-age sediments
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
Nur, Bilge; Kusgoz, Adem; Bayram, Mehmet; Nur, Metin; Kayipmaz, Saadettin; Yildirim, Sina
2012-01-01
Objective: To evaluate the applicability of Demirjian and Nolla methods for northeastern Turkish population. Material and Method: A retrospective study was performed on panoramic radiographs of 673 subjects aged 5–15.9 years. The mean dental age (DA) according to the Demirjian and Nolla methods were compared to the mean chronological age (CA). Results: The mean CA of the study sample was 10.37±2.90 and 10.03±2.81 years for females and males, respectively. Using the Demirjian method, the mean estimated DA was 11.26±3.02 years for females and 10.87±2.96 years for males. For Nolla method, the mean estimated DA was 9.80±3.41 and 9.53±3.14 years for females and males, respectively. The mean differences between the CA and DA according to the Demirjian and Nolla methods were 0.86 and -0.54 years for total study sample. Conclusion: Nolla method was found to be a more accurate method for estimating DA in northeastern Turkish population. Key words:Dental age, demirjian method, nolla method, chronological age. PMID:22549686
Estimating Age Ratios and Size of Pacific Walrus Herds on Coastal Haulouts using Video Imaging
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
Estimating age ratios and size of Pacific walrus herds on coastal haulouts using video imaging
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.
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. PMID:23936106
NASA Astrophysics Data System (ADS)
Nakano, Shinya; Suzuki, Kazue; Kawamura, Kenji; Parrenin, Frederic; Higuchi, Tomoyuki
2015-04-01
A technique for estimating the age-depth relationship and its uncertainty in ice cores has been developed. The age-depth relationship is mainly determined by the accumulation of snow at the site of the ice core and the thinning process due to the horizontal stretching and vertical compression of an ice layer. However, both the accumulation process and the thinning process are not fully known. In order to appropriately estimate the age as a function of depth, it is crucial to incorporate observational information into a model describing the accumulation and thinning processes. In the proposed technique, the age as a function of depth is estimated from age markers and time series of δ18O data. The estimation is achieved using a method combining a sequential Monte Carlo method and the Markov chain Monte Carlo method as proposed by Andrieu et al. (2010). In this hybrid method, the posterior distributions for the parameters in the models for the accumulation and thinning processes are basically computed using a way of the standard Metropolis-Hastings method. Meanwhile, sampling from the posterior distribution for the age-depth relationship is achieved by using a sequential Monte Carlo approach at each iteration of the Metropolis-Hastings method. A sequential Monte Carlo method normally suffers from the degeneracy problem, especially in cases that the number of steps is large. However, when it is combined with the Metropolis-Hastings method, the degeneracy problem can be overcome by collecting a large number of samples obtained by many iterations of the Metropolis-Hastings method. We will demonstrate the result obtained by applying the proposed technique to the ice core data from Dome Fuji in Antarctica.
Age estimation standards for a Western Australian population using the coronal pulp cavity index.
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. PMID:23664550
Listener estimations of talker age: A meta-analysis of the literature.
Hunter, Eric J; Ferguson, Sarah Hargus; Newman, Catherine Anne
2016-10-01
Numerous studies, most of them cross-sectional studies using one sample per talker, have demonstrated that listeners make relatively accurate age judgments from hearing talkers' voices. The current study analyzed the results of several such direct age estimation studies to characterize better the perception of talker age over a larger number of individuals. A review of the direct age estimation literature was performed. Data sets from seven papers were reconstituted, and an analysis of the combined data (meta-analysis) including 530 data points was conducted. The reconstituted and combined data included talkers aged 10-90. Listeners appeared to overestimate age when talkers were younger and to underestimate it when talkers were older. PMID:26079468
Technology Transfer Automated Retrieval System (TEKTRAN)
We report on the accuracy of using near-infrared spectroscopy (NIRS) to predict the age of Anopheles mosquitoes reared from wild larvae and a mixed age-wild adult population collected from pit traps after exposure to pyrethroids. The mosquitoes reared from wild larvae were estimated as ,7 or $7 d ol...
Comparison of rainbow smelt age estimates from fin rays and otoliths
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.
The EpiTect Methyl qPCR Assay as novel age estimation method in forensic biology.
Mawlood, Shakhawan K; Dennany, Lynn; Watson, Nigel; Pickard, Benjamin S
2016-07-01
Human aging is associated with epigenetic modification of the genome. DNA methylation at cytosines appears currently as the best characterised modification that occurs during the mammalian lifetime. Such methylation changes at regulatory region can provide insights to track contributor age for criminal investigation. The EpiTect Methyl II PCR system (QIAGEN) was used to compare methylation levels of CpG islands in the promoter regions of a number of age related genes, of which four successfully showed changes across the lifespan (NPTX2, KCNQ1DN, GRIA2 and TRIM58). This technique is based on the detection of remaining input genome after digestion with a methylation-sensitive restriction enzyme. This study examined DNA specimens from 80 female subjects of various ages (18-91 years) obtained from blood, using primers designed to flank the studied gene loci. The data obtained from DNA methylation quantification showed successful discrimination among volunteered ages. Overall, the difference between predicted and real age was about 11 years and absolute mean differences (AMD) was only 7.2 years error. We suggest the EpiTect system can be used as fast and simple innovative tool in future forensic age estimation. PMID:27108355
Cardoso, Hugo F V
2007-03-01
Liversidge and colleagues developed a method for predicting the age of immature skeletal remains based on the length of developing teeth. This quantitative method combines dental data from both jaws, except for the permanent lateral incisor, and because there are reasons to suspect that these two types of data are not identical and should not be combined, it raises concerns regarding the accuracy of the technique when applied differently to each jaw. In this study, the differential accuracy of the method was test when applied to the maxillary and mandibular dentition. The test sample is comprised of 57 Portuguese subadult skeletons of known age at death. Results suggest an overall high consistency between estimates obtained from both jaws, but for the permanent dentition only. In the deciduous dentition the age estimates obtained from the maxillary teeth tend to be greater than the age estimates obtained from the mandibular pair, and the differences are significant for the incisors and canine. Additionally, ages obtained from the maxillary deciduous canine also differ significantly from true chronological age. In the permanent dentition there were no differences between the ages provided by both jaws but both the maxillary and mandibular second molars show a significant tendency to underestimate true chronological age. Although this study cannot validate completely the method presented by Liversidge and colleagues, it does provide an important test to its accuracy and calls for further research into its overall performance, particularly with respect to the results obtained from both jaws. PMID:17316246
Ramsthaler, F; Proschek, P; Betz, W; Verhoff, M A
2009-05-01
Possible biological side effects of exposure to X-rays are stochastic effects such as carcinogenesis and genetic alterations. In recent years, a number of new studies have been published about the special cancer risk that children may suffer from diagnostic X-rays. Children and adolescents who constitute many of the probands in forensic age-estimation proceedings are considerably more sensitive to the carcinogenic risks of ionizing radiation than adults. Established doses for X-ray examinations in forensic age estimations vary from less than 0.1 microSv (left hand X-ray) up to more than 800 microSv (computed tomography). Computed tomography in children, as a relatively high-dose procedure, is of particular interest because the doses involved are near to the lower limit of the doses observed and analyzed in A-bombing survivor studies. From these studies, direct epidemiological data exist concerning the lifetime cancer risk. Since there is no medical indication for forensic age examinations, it should be stressed that only safe methods are generally acceptable. This paper reviews current knowledge on cancer risks associated with diagnostic radiation and aims to help forensic experts, dentists, and pediatricians evaluate the risk from radiation when using X-rays in age-estimation procedures. PMID:19153756
Chopra, O.K
1994-08-01
This report presents a revision of the procedure and correlations presented earlier in NUREG/CR-4513, ANL-90/42 (June 1991) for predicting the change in mechanical properties of cast stainless steel components due to thermal aging during service in light water reactors at 280-330{degrees}C (535-625{degrees}F). The correlations presented in this report are based on an expanded data base and have been optimized with mechanical-property data on cast stainless steels aged up to {approx}58,000 h at 290-350{degrees}C (554-633{degrees}F). The fracture toughness J-R curve, tensile stress, and Charpy-impact energy of aged cast stainless steels are estimated from known material information. Mechanical properties of a specific cast stainless steel are estimated from the extent and kinetics of thermal embrittlement. Embrittlement of cast stainless steels is characterized in terms of room-temperature Charpy-impact energy. Charpy-impact energy as a function of time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which are also determined from the chemical composition. The initial impact energy of the unaged steel is required for these estimations. Initial tensile flow stress is needed for estimating the flow stress of the aged material. The fracture toughness J-R curve for the material is then obtained by correlating room-temperature Charpy-impact energy with fracture toughness parameters. The values of J{sub IC} are determined from the estimated J-R curve and flow stress. A common {open_quotes}predicted lower-bound{close_quotes} J-R curve for cast stainless steels of unknown chemical composition is also defined for a given grade of steel, range of ferrite content, and temperature. Examples of estimating mechanical properties of cast stainless steel components during reactor service are presented.
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.
Use of soil catena field data for estimating relative ages of moraines
Birkeland, P.W.; Berry, M.E. ); Swanson, D.K. )
1991-03-01
Soils at the crests of moraines are commonly used to estimate the relative ages of moraines. However, for various pedologic and geomorphic reasons, soil development at crest sites may not truly reflect the time since moraine formation; for example, some crest soils on moraines of greatly different age are similar in morphology and development. Soil catena data for soils at several sites aligned downslope from the crest can greatly improve on the usefulness of soil data for estimating moraine ages. For this purpose, the authors use the weighted mean catena profile development index, which condenses field data for all of the soils in each catena into a single value.
López-Gil, N; Artal, P
1997-05-01
We compared retinal point-spread functions obtained by the double-pass method with two different wave-lengths, green (543 nm) and near-infrared (780 nm), in both cases under the best conditions of focus. The best refractive state at each wavelength was determined with two procedures: subjective refraction and analysis of the recorded double-pass images as a function of focus. Since the refraction results agree quite well, we assume that in both cases, green and near-infrared light, most of the light of the central core in the double-pass images comes from a layer close to that of the photoreceptors. The central spread of the double-pass images was also quite similar for the two wavelengths: a width of approximately 2-3 arcmin at half-intensity relative to the peak. However, larger differences were found in the tails of the images, with the infrared images presenting a larger scattering halo, probably as a result of a more important contribution of retinal and choroidal scattering for that wavelength. By using the central core in the double-pass images and ignoring the tails, we can use the near-infrared data to predict the modulation transfer function measured with the use of green light. These results raise the possibility of using near-infrared illumination the double-pass method to estimate the optical performance of the human eye. PMID:9114507
Mohammed, Rezwana Begum; Rao, Dola Srinivasa; Goud, Alampur Srinivas; Sailaja, S.; Thetay, Anshuj Ajay Rao; Gopalakrishnan, Meera
2015-01-01
Introduction: 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. Materials and Methods: 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. Results: 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). Conclusion: 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. PMID:26229357
Qai, Qiang; Rushton, Gerald; Bhaduri, Budhendra L; Bright, Eddie A; Coleman, Phil R
2006-01-01
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, and 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.
A method for estimating age of Danish medieval sub-adults based on long bone length.
Primeau, Charlotte; Friis, Laila; Sejrsen, Birgitte; Lynnerup, Niels
2012-07-01
The preferred method for aging archaeological sub-adult skeletons is by dental examination. In cases where no dental records are available, age estimation may be performed according to epiphyseal union, skeletal elements or diaphyseal lengths. Currently no data have been produced specifically for aging archaeological Danish sub-adults from the medieval period based on diaphyseal lengths. The problem with using data on Danish samples, which have been derived from a different population, is the possibility of skewing age estimates. In this study 58 Danish archaeological sub-adults were examined, aged from approximately six years to twenty-one years. The samples were aged according to two dental methods: Haavikko and Ubelaker. Regression formulae were constructed for aging according to their diaphyseal lengths both for individual long bones and combinations of upper and lower long bones. This study indicated that with the regression formulae developed, estimation of age can be done with reasonable results on Danish sub-adults. The Danish data were then compared to data from a different archaeological sample and a modern sample. It showed that the modern data indicated a consistently lower age compared to this sample which increased until reaching a maximum of nearly five years and six months. When comparing the archaeological data to this study, the growth profile crossed over at 12.5 years with a maximum age difference before the cross point of two years and three months lower for the archaeological data. After the cross point there was a maximum difference of three years and four months higher for the archaeological data. This study has shown the importance of using data for age estimation for archaeological material which has been developed specifically for that population. In addition it has presented a possible solution for Danish sub-adult material when dental material is not available. PMID:22928354
2013-01-01
Background Clonal propagation is a particular reproductive system found in both the plant and animal kingdoms, from human parasites to clonally propagated crops. Clonal diversity provides information about plant and animal evolutionary history, i.e. how clones spread, or the age of a particular clone. In plants, this could provide valuable information about agrobiodiversity dynamics and more broadly about the evolutionary history of a particular crop. We studied the evolutionary history of yam, Dioscorea rotundata. In Africa, Yam is cultivated by tuber clonal propagation. Results We used 12 microsatellite markers to identify intra-clonal diversity in yam varieties. We then used this diversity to assess the relative ages of clones. Using simulations, we assessed how Approximate Bayesian Computation could use clonal diversity to estimate the age of a clone depending on the size of the sample, the number of independent samples and the number of markers. We then applied this approach to our particular dataset and showed that the relative ages of varieties could be estimated, and that each variety could be ranked by age. Conclusions We give a first estimation of clone age in an approximate Bayesian framework. However the precise estimation of clone age depends on the precision of the mutation rate. We provide useful information on agrobiodiversity dynamics and suggest recurrent creation of varietal diversity in a clonally propagated crop. PMID:24219837
Hargrove, J W; Ackley, S F
2015-06-01
Mortality estimates are central to understanding tsetse fly population dynamics, but are difficult to acquire from wild populations. They can be obtained from age distribution data but, with limited data, it is unclear whether the assumptions required to make the estimates are satisfied and, if not, how violations affect the estimates. We evaluate the assumptions required for existing mortality estimation techniques using long-term longitudinal ovarian dissection data from 144,106 female tsetse, Glossina pallidipes Austen, captured in Zimbabwe between 1988 and 1999. At the end of the hot-dry season each year, mean ovarian ages peaked, and maximum-likelihood mortality estimates declined to low levels, contrary to mark-recapture estimates, suggesting violations of the assumptions underlying the estimation technique. We demonstrate that age distributions are seldom stable for G. pallidipes at our study site, and hypothesize that this is a consequence of a disproportionate increase in the mortality of pupae and young adults at the hottest times of the year. Assumptions of age-independent mortality and capture probability are also violated, the latter bias varying with capture method and with pregnancy and nutritional status. As a consequence, mortality estimates obtained from ovarian dissection data are unreliable. To overcome these problems we suggest simulating female tsetse populations, using dynamical modelling techniques that make no assumptions about the stability of the age distribution. PMID:25804211
Stansfield, Fiona J.
2015-01-01
The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These ‘Age Reference Lines’ were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70–75 years. Methods to aid in molar identification and the sexing of found jaws were also identified. PMID:25970428
Stansfield, Fiona J
2015-01-01
The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years. Methods to aid in molar identification and the sexing of found jaws were also identified. PMID:25970428
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.
A method for estimating the dynamical age of FR II-type radio sources from multi-frequency data
NASA Astrophysics Data System (ADS)
Machalski, J.; Chyży, K. T.; Stawarz, Ł.; Kozieł, D.
2007-01-01
Context: Determining the ages of powerful radio sources is crucial for understanding galaxy evolution, the activity cycle of galactic nuclei, and their influence on the surrounding intergalactic medium. So far, several different methods for estimating the age of classical double radio galaxies have been proposed and widely used in the literature, although each of them faces difficulty due to observational limitations and/or freedom in choosing the underlying model assumptions. Aims: We propose a new approach to determining the ages of FR II type radio sources that, on one hand exploits a dynamical model developed for these objects by Kaiser et al. (1997, MNRAS, 292, 723) and, on the other hand, uses multifrequency radio observations not necessarily restricted to the high-resolution ones. Methods: In particular, we applied the assumed dynamical model to a number of FR II type radio galaxies observed at different radio frequencies and fit - for each frequency separately - the model's free parameters to the quantities of the observed sources. Such a procedure, which in fact enlarged a number of observables, enabled us to determine relatively precise ages and other crucial characteristics (like the jets' kinetic power) for the analyzed sources. Results: The resulting age estimates agree very well with those obtained with the "classical" spectral aging method for objects not older than 10 Myr, for which good-quality spectral data are available. However, this method is also applicable in the case of older sources than this and/or those for which the only available low-resolution radio data do not allow for detailed spectral aging studies. Interestingly, the estimated ages always correspond to the realistic values of the jets' advance velocity of ~0.01-0.1~c. Conclusions: . Our analysis indicates that the main factor precluding precise age determination for FR II type radio galaxies is related to the poorly known shape of the initial electron energy distribution injected
Gurses, Murat Serdar; Inanir, Nursel Turkmen; Gokalp, Gokhan; Fedakar, Recep; Tobcu, Eren; Ocakoglu, Gokhan
2016-09-01
Forensic age estimation, a recent topic of research in forensic medicine, is of primary importance to criminal and civil law. Previous studies indicate that the observation of medial clavicular ossification allows for age discrimination along the completed 18th and 21st years of life. Experts recommend that the Schmeling and Kellinghaus methods be used together. In this study, we used these staging methods to retrospectively analyze 725 case studies (385 males, 340 females) of thin-slice computed tomography (CT) images, ranging from 0.6 to 1 mm in thickness, from individuals aged 10 to 35 years. Stage 1 was found at 18 years of age maximum for males, whereas it was found at 17 years of age for females. Stage 2a was found at 18 years of age maximum for both genders. Stage 3c was initially observed at 18 years for both genders. Stage 4 was initially found at 21 years for males and 20 years for females. Stage 5 was initially observed at 25 years for both genders. Of note, stage 3c was found close to 19 years of age for both genders (18.92 years for male, 18.99 years for female), and it may be employed to differentiate along the age majority cutoff. The data obtained from our study were consistent with previous studies. We believe that such a comprehensive database will greatly contribute to future studies focusing on medial clavicular ossification based on thin-slice CT. Moreover, we also recommend that if medial clavicular ossification based on CT is to be examined for forensic age estimation, both methods should be employed together. PMID:27352083
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
La Padula, Simone; Hersant, Barbara; SidAhmed, Mounia; Niddam, Jeremy; Meningaud, Jean Paul
2016-07-01
Most patients requesting aesthetic rejuvenation treatment expect to look healthier and younger. Some scales for ageing assessment have been proposed, but none is focused on patient age prediction. The aim of this study was to develop and validate a new facial rating scale assessing facial ageing sign severity. One thousand Caucasian patients were included and assessed. The Rasch model was used as part of the validation process. A score was attributed to each patient, based on the scales we developed. The correlation between the real age and scores obtained, the inter-rater reliability and test-retest reliability were analysed. The objective was to develop a tool enabling the assigning of a patient to a specific age range based on the calculated score. All scales exceeded criteria for acceptability, reliability and validity. The real age strongly correlated with the total facial score in both sex groups. The test-retest reliability confirmed this strong correlation. We developed a facial ageing scale which could be a useful tool to assess patients before and after rejuvenation treatment and an important new metrics to be used in facial rejuvenation and regenerative clinical research. PMID:27221225
Letter report: Population estimates by age, sex and race for 10-county study area
Pittenger, D B
1992-02-01
The Hanford Environmental Does Reconstruction (HEDR) Project was established to estimate radiation doses that people could have received from nuclear operations at the Hanford Site since 1944. To identify groups that may have received doses, population estimates containing age, race, and sex detail for ten counties in Washington and Oregon for the years 1940 to 1980 were prepared by the Demographics Laboratory under a subcontract with the Pacific Northwest Laboratory (PNL). A data base of population information was developed from census reports and published and unpublished collections from the Washington State Office of Financial Management and Center for Population Research. Three estimation methods were then explored: the cohort-component model, cohort interpolation, and age-group interpolation. The estimates generated through cohort and age-group interpolation are considered adequate for initial use in the HEDR Project. Results are presented in two forms: (1) county populations by sex and single year of age and (2) county populations by sex and race for age groupings. These results are made available to the HEDR Project for further refinement into population estimates by county census divisions.
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).
Bijjaragi, Shobha C; Sangle, Varsha A; Saraswathi, FK; Patil, Veerendra S; Ashwini Rani, SR; Bapure, Sunil K
2015-01-01
Context: 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. Aims: 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. Settings and Design: Clinical setting and computerized design. Subjects and Methods: 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). Statistical Analysis Used: Pearson correlation, paired t-test, linear regression analysis. Results: 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. Conclusions: 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. PMID:26097317
Implications of age and conditional survival estimates for patients with melanoma
Banerjee, Mousumi; Lao, Christopher D.; Wancata, Lauren M.; Muenz, Daniel G.; Haymart, Megan R.; Wong, Sandra L.
2016-01-01
Objective Overall cancer incidence is decreasing while melanoma cases increase. Conditional survival estimates offer a more accurate prognosis for patients as they survive past diagnosis. It is unknown the effect age and stage has on a melanoma patient’s conditional survival estimate. Methods Surveillance, Epidemiology, End Results (SEER) data was utilized, identifying new diagnosis cutaneous melanoma patients (N=95,041), from 1998–2005, with up to 12 year follow up. Estimates of disease-specific survival by stage and age were determined by Cox regression and transformed to estimate conditional five-year survival. Results Localized melanoma patients have an excellent five-year survival at diagnosis and subsequent years. For patients with localized and regional disease, an age effect is present for disease-specific mortality when comparing older patients (70–79 years) to younger patients (<30 years): hazard ratio (HR) for mortality 3.79 (95% confidence interval (CI) 3.01–4.84) and HR 2.36 (95% CI 1.93–2.91), respectively. No age effect difference is observed in disease-specific survival for advanced disease: HR 1.14 (95% CI 0.87–1.53). Over time conditional survival estimates improve for older patients with localized and regional disease. This improvement is not seen in distant disease nor is the age gradient. Conclusions Disease-specific mortality and conditional survival for patients with localized and regional melanoma is initially impacted by older age with effects dissipating over time. Age does not affect survival in patients with advanced disease. Understanding the conditional five-year disease-specific survival of melanoma based on age and stage can help patients and physicians, informing decision making about treatment and surveillance. PMID:26479218
Implications of age and conditional survival estimates for patients with melanoma.
Banerjee, Mousumi; Lao, Christopher D; Wancata, Lauren M; Muenz, Daniel G; Haymart, Megan R; Wong, Sandra L
2016-02-01
Overall cancer incidence is decreasing, whereas melanoma cases are increasing. Conditional survival estimates offer a more accurate prognosis for patients the farther they are from time of diagnosis. The effect of age and stage on a melanoma patient's conditional survival estimate is unknown. Surveillance, Epidemiology, and End Results data were utilized to identify newly diagnosed cutaneous melanoma patients (N=95 041), from 1998 to 2005, with up to 12 years of follow-up. Estimates of disease-specific survival by stage and age were determined by Cox regression analysis and transformed to estimated conditional 5-year survival. Localized melanoma patients have an excellent 5-year survival at diagnosis and over subsequent years. For patients with localized and regional disease, an age effect is present for disease-specific mortality when comparing older patients (70-79 years) with younger patients (<30 years): hazard ratio (HR) for mortality 3.79 [95% confidence interval (CI) 3.01-4.84] and HR 2.36 (95% CI 1.93-2.91), respectively. No age effect difference is observed in disease-specific survival for advanced disease: HR 1.14 (95% CI 0.87-1.53). Over time, conditional survival estimates improve for older patients with localized and regional disease. This improvement is not seen in distant disease, neither is the age gradient. Disease-specific mortality and conditional survival for patients with localized and regional melanomas are initially impacted by older age, with effects dissipating over time. Age does not affect survival in patients with advanced disease. Understanding the conditional 5-year disease-specific survival of melanoma based on age and stage can help patients and physicians, informing decision-making about treatment and surveillance. PMID:26479218
Computed tomography evaluation of the iliac crest apophysis: age estimation in living individuals.
Ekizoglu, Oguzhan; Inci, Ercan; Erdil, Irem; Hocaoglu, Elif; Bilgili, Mustafa Gokhan; Kazimoglu, Cemal; Reisoglu, Ali; Can, Ismail Ozgur
2016-07-01
Determination of the ossification properties of the iliac apophysis is important not only in the clinical evaluation of patients undergoing orthopedic surgery but also in age estimation studies for forensic purposes. The literature includes both anthropological and radiological (conventional radiography, ultrasonography, and magnetic resonance imaging modalities) investigations of the different staging systems used for these purposes. In this study, we assessed the utility of computed tomography (CT) of the iliac crest apophysis in estimating forensic age. CT scans of the iliac crest apophysis of 380 patients (187 females, 193 males, and 10-29 years of age) were evaluated according to the four-stage system. Further subclassification did not give data properly due to the reference length measurement of the iliac wing with CT. Thus, in our series, stage 2 was first seen in 12 years of age and stage 3 in those 14 years of age in both sexes and on both sides of the pelvis. Stage 4 was first seen in 17 years of both sexes but only on the right side; on the left side, it appeared in females 18 years of age and in males 17 years of age. Present data was found consistent with previous pelvic radiographic findings. First seen ages for stage 2 and 3 are 12 and 14 years respectively which presented valuable information for legally important age thresholds. However, disadvantages of CT, including high-dose radiation exposure to gonads, the difficulty of evaluating the iliac crest, and the age boundary of 17 years, could make this method infeasible, as compared with hand wrist and pelvic radiographic methods. CT of the iliac crest has probably a greater utility where preexisting CT scans of the pelvic region are available, and it may be considered as a supportive method for age-estimation purposes. PMID:26914804
NASA Astrophysics Data System (ADS)
King, J. R.; McPhie, R. P.
2015-05-01
The spotted ratfish (Hydrolagus colliei) is a chimaeroid ranging from southeast Alaska to Baja California and found at depths of up to 1029 m. Despite being widespread and ubiquitous, few biological parameter estimates exist for spotted ratfish due to a lack of suitable ageing structures to estimate age and growth. We present preliminary results of age, growth and maturity estimates based on a new method in which tritor ridges are counted on the vomerine tooth plate. We also provide a method for estimating the number of worn tritor ridges based on tooth plate diameter measurements for the spotted ratfish. The tritor ridges are distinct bumps that are easy to identify and precision estimates between readers suggests that this method is transferable. Tritor ridges are a potential structure for estimating age in H. colliei and we provide recommendations for future research to improve the method. We sampled 269 spotted ratfish captured in trawl surveys off the coast British Columbia ranging in size from 74 to 495 mm in precaudal length (PCL). The estimated ages ranged from 2 to 16 years for males and from 2 to 21 years for females. The von Bertalanffy, von Bertalanffy with known size at birth, Gompertz and logistic growth models were fitted to the data. Based on Akaike information criterion corrected for sample size and number of parameters estimated, the logistic growth curve was selected as most suitable. The logistic growth model yielded the following parameter estimates: Linf=407.22 mm (PCL), k=0.23 year-1, t0=-7.06 years for males; L∞=494.52 mm (PCL), k=0.26 year-1, t0=-8.35 years for females. Estimated ages at 50% maturity were 12 and 14 years for males and females, respectively. Correspondingly, the size at 50% maturity estimates was smaller for males (302 mm, PCL) than females (393 mm, PCL). Both estimates are larger than those made for spotted ratfish off of California indicating regional differences in life history traits for this species. Our preliminary
Age estimation in Indian children and adolescents in the NCR region of Haryana: A comparative study
Gupta, Swati; Mehendiratta, Monica; Rehani, Shweta; Kumra, Madhumani; Nagpal, Ruchi; Gupta, Ramakant
2015-01-01
Introduction: Age estimation is a preliminary step in the identification of an individual. It is a crucial and often most critical step for forensic experts. The assessment has been standardized utilizing common dental diagnostic x-rays, but most such age-estimating systems are European population-based and their applicability has not been determined in the context of the Indian population. Aims and Objectives: To assess the applicability and to compare the methods of dental age estimation by Demirjian's method and the same method as modified by Willems (i.e. the Willems method) in Indian children of the National Capital Region (NCR). Also, to find a correlation among skeletal maturity using the Cervical vertebrae maturation index (CVMI), dental maturity, and chronological age in the same population. Materials and Methods: This cross-sectional study was conducted using dental radiographs of 70 orthodontic patients (37 males, 33 females) in the age range 9-16 years selected by simple random sampling. pantomogram were used to estimate dental age by Demirjian's method and the Willems method using their scoring tables. Lateral cephalograms were used to estimate skeletal maturity using CVMI. The latter was compared with Demirjian's stage for mandibular left second molar. Results: Overestimation of age among males by 0.856 years and 0.496 years was found by Demirjian's and the Willems methods, respectively. Among females, both the methods underestimated the age by 0.31 years and 0.45 years, respectively. Demirjian's stage G corresponded to CVMI stage 3 in males and stage 2 in females. Conclusion: In our study, the Willems method has proved to be more accurate for age estimation among Indian males, and Demirjian's method for Indian females. A statistically significant association appeared between Demirjian's stages and CVMI among both males and females. Our study recommends the derivation of a regression formula by studying a larger section of the Indian population
Radiological pitfalls of age estimation in adopted children: a case report.
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. PMID:25786535
Sikulu, Maggy T.; Majambere, Silas; Khatib, Bakar O.; Ali, Abdullah S.; Hugo, Leon E.; Dowell, Floyd E.
2014-01-01
We report on the accuracy of using near-infrared spectroscopy (NIRS) to predict the age of Anopheles mosquitoes reared from wild larvae and a mixed age-wild adult population collected from pit traps after exposure to pyrethroids. The mosquitoes reared from wild larvae were estimated as <7 or ≥7 d old with an overall accuracy of 79%. The age categories of Anopheles mosquitoes that were not exposed to the insecticide papers were predicted with 78% accuracy whereas the age categories of resistant, susceptible and mosquitoes exposed to control papers were predicted with 82%, 78% and 79% accuracy, respectively. The ages of 85% of the wild-collected mixed-age Anopheles were predicted by NIRS as ≤8 d for both susceptible and resistant groups. The age structure of wild-collected mosquitoes was not significantly different for the pyrethroid-susceptible and pyrethroid-resistant mosquitoes (P = 0.210). Based on these findings, NIRS chronological age estimation technique for Anopheles mosquitoes may be independent of insecticide exposure and the environmental conditions to which the mosquitoes are exposed. PMID:24594705
Age estimation based on pelvic ossification using regression models from conventional radiography.
Zhang, Kui; Dong, Xiao-Ai; Fan, Fei; Deng, Zhen-Hua
2016-07-01
To establish regression models for age estimation from the combination of the ossification of iliac crest and ischial tuberosity. One thousand three hundred and seventy-nine conventional pelvic radiographs at the West China Hospital of Sichuan University between January 2010 and June 2012 were evaluated retrospectively. The receiver operating characteristic analysis was performed to measure the value of estimation of 18 years of age with the classification scheme for the iliac crest and ischial tuberosity. Regression analysis was performed, and formulas for calculating approximate chronological age according to the combination developmental status of the ossification for the iliac crest and ischial tuberosity were developed. The areas under the receiver operating characteristic (ROC) curves were above 0.9 (p < 0.001), indicating a good prediction of the grading systems, and the cubic regression model was found to have the highest R-square value (R (2) = 0.744 for female and R (2) = 0.753 for male). The present classification scheme for apophyseal iliac crest ossification and the ischial tuberosity may be used for age estimation. And the present established cubic regression model according to the combination developmental status of the ossification for the iliac crest and ischial tuberosity can be used for age estimation. PMID:27169673
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.